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GNU C Library master sources branch arjun/backport-c579f48-to-2.24 created. glibc-2.24-51-g7b60553


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The branch, arjun/backport-c579f48-to-2.24 has been created
        at  7b60553e360731338631ccdda71590ac5deca137 (commit)

- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=7b60553e360731338631ccdda71590ac5deca137

commit 7b60553e360731338631ccdda71590ac5deca137
Author: Arjun Shankar <arjun.is@lostca.se>
Date:   Tue Jun 6 17:23:21 2017 +0200

    Use test-driver in sysdeps/unix/sysv/linux/tst-clone2.c
    
    (cherry picked from commit fdc543919a3d8578631a492e1227c2cd8f5ecec7)

diff --git a/ChangeLog b/ChangeLog
index 1bb6135..33d05e4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-06-07  Arjun Shankar  <arjun.is@lostca.se>
+
+	* sysdeps/unix/sysv/linux/tst-clone2.c: Do not
+	include test-skeleton.c.
+	Include support/check.h and support/test-driver.c.
+
 2016-11-24  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
diff --git a/sysdeps/unix/sysv/linux/tst-clone2.c b/sysdeps/unix/sysv/linux/tst-clone2.c
index 0da9e54..1472311 100644
--- a/sysdeps/unix/sysv/linux/tst-clone2.c
+++ b/sysdeps/unix/sysv/linux/tst-clone2.c
@@ -32,10 +32,7 @@
 
 #include <stackinfo.h>  /* For _STACK_GROWS_{UP,DOWN}.  */
 
-static int do_test (void);
-
-#define TEST_FUNCTION do_test ()
-#include <test-skeleton.c>
+#include <support/check.h>
 
 static int sig;
 static int pipefd[2];
@@ -145,3 +142,5 @@ do_test (void)
 
   return ret;
 }
+
+#include <support/test-driver.c>

http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=206e03248c3f575e83c13f2aa709fa55c67e51c2

commit 206e03248c3f575e83c13f2aa709fa55c67e51c2
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Mon Oct 10 15:08:39 2016 -0300

    Remove cached PID/TID in clone
    
    This patch remove the PID cache and usage in current GLIBC code.  Current
    usage is mainly used a performance optimization to avoid the syscall,
    however it adds some issues:
    
      - The exposed clone syscall will try to set pid/tid to make the new
        thread somewhat compatible with current GLIBC assumptions.  This cause
        a set of issue with new workloads and usecases (such as BZ#17214 and
        [1]) as well for new internal usage of clone to optimize other algorithms
        (such as clone plus CLONE_VM for posix_spawn, BZ#19957).
    
      - The caching complexity also added some bugs in the past [2] [3] and
        requires more effort of each port to handle such requirements (for
        both clone and vfork implementation).
    
      - Caching performance gain in mainly on getpid and some specific
        code paths.  The getpid performance leverage is questionable [4],
        either by the idea of getpid being a hotspot as for the getpid
        implementation itself (if it is indeed a justifiable hotspot a
        vDSO symbol could let to a much more simpler solution).
    
        Other usage is mainly for non usual code paths, such as pthread
        cancellation signal and handling.
    
    For thread creation (on stack allocation) the code simplification in fact
    adds some performance gain due the no need of transverse the stack cache
    and invalidate each element pid.
    
    Other thread usages will require a direct getpid syscall, such as
    cancellation/setxid signal, thread cancellation, thread fail path (at
    create_thread), and thread signal (pthread_kill and pthread_sigqueue).
    However these are hardly usual hotspots and I think adding a syscall is
    justifiable.
    
    It also simplifies both the clone and vfork arch-specific implementation.
    And by review each fork implementation there are some discrepancies that
    this patch also solves:
    
      - microblaze clone/vfork does not set/reset the pid/tid field
      - hppa uses the default vfork implementation that fallback to fork.
        Since vfork is deprecated I do not think we should bother with it.
    
    The patch also removes the TID caching in clone. My understanding for
    such semantic is try provide some pthread usage after a user program
    issue clone directly (as done by thread creation with CLONE_PARENT_SETTID
    and pthread tid member).  However, as stated before in multiple discussions
    threads, GLIBC provides clone syscalls without further supporting all this
    semantics.
    
    I ran a full make check on x86_64, x32, i686, armhf, aarch64, and powerpc64le.
    For sparc32, sparc64, and mips I ran the basic fork and vfork tests from
    posix/ folder (on a qemu system).  So it would require further testing
    on alpha, hppa, ia64, m68k, nios2, s390, sh, and tile (I excluded microblaze
    because it is already implementing the patch semantic regarding clone/vfork).
    
    [1] https://codereview.chromium.org/800183004/
    [2] https://sourceware.org/ml/libc-alpha/2006-07/msg00123.html
    [3] https://sourceware.org/bugzilla/show_bug.cgi?id=15368
    [4] http://yarchive.net/comp/linux/getpid_caching.html
    
    	* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
    	* nptl/allocatestack.c (allocate_stack): Likewise.
    	(__reclaim_stacks): Likewise.
    	(setxid_signal_thread): Obtain pid through syscall.
    	* nptl/nptl-init.c (sigcancel_handler): Likewise.
    	(sighandle_setxid): Likewise.
    	* nptl/pthread_cancel.c (pthread_cancel): Likewise.
    	* sysdeps/unix/sysv/linux/pthread_kill.c (__pthread_kill): Likewise.
    	* sysdeps/unix/sysv/linux/pthread_sigqueue.c (pthread_sigqueue):
    	Likewise.
    	* sysdeps/unix/sysv/linux/createthread.c (create_thread): Likewise.
    	* sysdeps/unix/sysv/linux/getpid.c: Remove file.
    	* nptl/descr.h (struct pthread): Change comment about pid value.
    	* nptl/pthread_getattr_np.c (pthread_getattr_np): Remove thread
    	pid assert.
    	* sysdeps/unix/sysv/linux/pthread-pids.h (__pthread_initialize_pids):
    	Do not set pid value.
    	* nptl_db/td_ta_thr_iter.c (iterate_thread_list): Remove thread
    	pid cache check.
    	* nptl_db/td_thr_validate.c (td_thr_validate): Likewise.
    	* sysdeps/aarch64/nptl/tcb-offsets.sym: Remove pid offset.
    	* sysdeps/alpha/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/arm/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/hppa/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/i386/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/ia64/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/m68k/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/microblaze/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/mips/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/nios2/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/powerpc/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/s390/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/sh/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/sparc/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/tile/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/x86_64/nptl/tcb-offsets.sym: Likewise.
    	* sysdeps/unix/sysv/linux/aarch64/clone.S: Remove pid and tid caching.
    	* sysdeps/unix/sysv/linux/alpha/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/hppa/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/ia64/clone2.S: Likewise.
    	* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/nios2/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/s390/s390-32/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/s390/s390-64/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/sh/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/tile/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/aarch64/vfork.S: Remove pid set and reset.
    	* sysdeps/unix/sysv/linux/alpha/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/arm/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/i386/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/ia64/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/m68k/clone.S: Likewise.
    	* sysdeps/unix/sysv/linux/m68k/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/mips/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/nios2/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/s390/s390-32/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/s390/s390-64/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/sh/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/tile/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/x86_64/vfork.S: Likewise.
    	* sysdeps/unix/sysv/linux/tst-clone2.c (f): Remove direct pthread
    	struct access.
    	(clone_test): Remove function.
    	(do_test): Rewrite to take in consideration pid is not cached anymore.
    
    (cherry picked from commit c579f48edba88380635ab98cb612030e3ed8691e)

diff --git a/ChangeLog b/ChangeLog
index f0c8e7d..1bb6135 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,84 @@
+2016-11-24  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	* sysdeps/nptl/fork.c (__libc_fork): Remove pid cache setting.
+	* nptl/allocatestack.c (allocate_stack): Likewise.
+	(__reclaim_stacks): Likewise.
+	(setxid_signal_thread): Obtain pid through syscall.
+	* nptl/nptl-init.c (sigcancel_handler): Likewise.
+	(sighandle_setxid): Likewise.
+	* nptl/pthread_cancel.c (pthread_cancel): Likewise.
+	* sysdeps/unix/sysv/linux/pthread_kill.c (__pthread_kill): Likewise.
+	* sysdeps/unix/sysv/linux/pthread_sigqueue.c (pthread_sigqueue):
+	Likewise.
+	* sysdeps/unix/sysv/linux/createthread.c (create_thread): Likewise.
+	* sysdeps/unix/sysv/linux/raise.c (raise): Remove old behaviour
+	comment.
+	* sysdeps/unix/sysv/linux/getpid.c: Remove file.
+	* nptl/descr.h (struct pthread): Change comment about pid value.
+	* nptl/pthread_getattr_np.c (pthread_getattr_np): Remove thread
+	pid assert.
+	* sysdeps/unix/sysv/linux/pthread-pids.h (__pthread_initialize_pids):
+	Do not set pid value.
+	* nptl_db/td_ta_thr_iter.c (iterate_thread_list): Remove thread
+	pid cache check.
+	* nptl_db/td_thr_validate.c (td_thr_validate): Likewise.
+	* sysdeps/aarch64/nptl/tcb-offsets.sym: Remove pid offset.
+	* sysdeps/alpha/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/arm/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/hppa/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/i386/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/ia64/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/m68k/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/microblaze/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/mips/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/nios2/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/powerpc/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/s390/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/sh/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/sparc/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/tile/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/x86_64/nptl/tcb-offsets.sym: Likewise.
+	* sysdeps/unix/sysv/linux/aarch64/clone.S: Remove pid and tid caching.
+	* sysdeps/unix/sysv/linux/alpha/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/arm/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/hppa/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/i386/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/ia64/clone2.S: Likewise.
+	* sysdeps/unix/sysv/linux/mips/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/nios2/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-32/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-64/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/sh/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc32/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc64/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/tile/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/aarch64/vfork.S: Remove pid set and reset.
+	* sysdeps/unix/sysv/linux/alpha/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/arm/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/i386/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/ia64/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/m68k/clone.S: Likewise.
+	* sysdeps/unix/sysv/linux/m68k/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/mips/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/nios2/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-32/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/s390/s390-64/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/sh/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/tile/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/x86_64/vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/hppa/pt-vfork.S: Likewise.
+	* sysdeps/unix/sysv/linux/tst-clone2.c (f): Remove direct pthread
+	struct access.
+	(clone_test): Remove function.
+	(do_test): Rewrite to take in consideration pid is not cached anymore.
+
 2016-09-26  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	* sysdeps/unix/sysdep.h (__INTERNAL_SYSCALL0): New macro.
diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
index 6b42b11..7365ca6 100644
--- a/nptl/allocatestack.c
+++ b/nptl/allocatestack.c
@@ -440,9 +440,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
       SETUP_THREAD_SYSINFO (pd);
 #endif
 
-      /* The process ID is also the same as that of the caller.  */
-      pd->pid = THREAD_GETMEM (THREAD_SELF, pid);
-
       /* Don't allow setxid until cloned.  */
       pd->setxid_futex = -1;
 
@@ -579,9 +576,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
 	  /* Don't allow setxid until cloned.  */
 	  pd->setxid_futex = -1;
 
-	  /* The process ID is also the same as that of the caller.  */
-	  pd->pid = THREAD_GETMEM (THREAD_SELF, pid);
-
 	  /* Allocate the DTV for this thread.  */
 	  if (_dl_allocate_tls (TLS_TPADJ (pd)) == NULL)
 	    {
@@ -875,9 +869,6 @@ __reclaim_stacks (void)
 	  /* This marks the stack as free.  */
 	  curp->tid = 0;
 
-	  /* The PID field must be initialized for the new process.  */
-	  curp->pid = self->pid;
-
 	  /* Account for the size of the stack.  */
 	  stack_cache_actsize += curp->stackblock_size;
 
@@ -903,13 +894,6 @@ __reclaim_stacks (void)
 	}
     }
 
-  /* Reset the PIDs in any cached stacks.  */
-  list_for_each (runp, &stack_cache)
-    {
-      struct pthread *curp = list_entry (runp, struct pthread, list);
-      curp->pid = self->pid;
-    }
-
   /* Add the stack of all running threads to the cache.  */
   list_splice (&stack_used, &stack_cache);
 
@@ -1054,9 +1038,9 @@ setxid_signal_thread (struct xid_command *cmdp, struct pthread *t)
     return 0;
 
   int val;
+  pid_t pid = __getpid ();
   INTERNAL_SYSCALL_DECL (err);
-  val = INTERNAL_SYSCALL (tgkill, err, 3, THREAD_GETMEM (THREAD_SELF, pid),
-			  t->tid, SIGSETXID);
+  val = INTERNAL_SYSCALL_CALL (tgkill, err, pid, t->tid, SIGSETXID);
 
   /* If this failed, it must have had not started yet or else exited.  */
   if (!INTERNAL_SYSCALL_ERROR_P (val, err))
diff --git a/nptl/descr.h b/nptl/descr.h
index 8e4938d..bc92abf 100644
--- a/nptl/descr.h
+++ b/nptl/descr.h
@@ -167,8 +167,8 @@ struct pthread
      therefore stack) used' flag.  */
   pid_t tid;
 
-  /* Process ID - thread group ID in kernel speak.  */
-  pid_t pid;
+  /* Ununsed.  */
+  pid_t pid_ununsed;
 
   /* List of robust mutexes the thread is holding.  */
 #ifdef __PTHREAD_MUTEX_HAVE_PREV
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index bdbdfed..48fab50 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -184,18 +184,12 @@ __nptl_set_robust (struct pthread *self)
 static void
 sigcancel_handler (int sig, siginfo_t *si, void *ctx)
 {
-  /* Determine the process ID.  It might be negative if the thread is
-     in the middle of a fork() call.  */
-  pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
-  if (__glibc_unlikely (pid < 0))
-    pid = -pid;
-
   /* Safety check.  It would be possible to call this function for
      other signals and send a signal from another process.  This is not
      correct and might even be a security problem.  Try to catch as
      many incorrect invocations as possible.  */
   if (sig != SIGCANCEL
-      || si->si_pid != pid
+      || si->si_pid != __getpid()
       || si->si_code != SI_TKILL)
     return;
 
@@ -243,19 +237,14 @@ struct xid_command *__xidcmd attribute_hidden;
 static void
 sighandler_setxid (int sig, siginfo_t *si, void *ctx)
 {
-  /* Determine the process ID.  It might be negative if the thread is
-     in the middle of a fork() call.  */
-  pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
   int result;
-  if (__glibc_unlikely (pid < 0))
-    pid = -pid;
 
   /* Safety check.  It would be possible to call this function for
      other signals and send a signal from another process.  This is not
      correct and might even be a security problem.  Try to catch as
      many incorrect invocations as possible.  */
   if (sig != SIGSETXID
-      || si->si_pid != pid
+      || si->si_pid != __getpid ()
       || si->si_code != SI_TKILL)
     return;
 
diff --git a/nptl/pthread_cancel.c b/nptl/pthread_cancel.c
index 1419baf..89d02e1 100644
--- a/nptl/pthread_cancel.c
+++ b/nptl/pthread_cancel.c
@@ -22,7 +22,7 @@
 #include "pthreadP.h"
 #include <atomic.h>
 #include <sysdep.h>
-
+#include <unistd.h>
 
 int
 pthread_cancel (pthread_t th)
@@ -66,19 +66,11 @@ pthread_cancel (pthread_t th)
 #ifdef SIGCANCEL
 	  /* The cancellation handler will take care of marking the
 	     thread as canceled.  */
-	  INTERNAL_SYSCALL_DECL (err);
-
-	  /* One comment: The PID field in the TCB can temporarily be
-	     changed (in fork).  But this must not affect this code
-	     here.  Since this function would have to be called while
-	     the thread is executing fork, it would have to happen in
-	     a signal handler.  But this is no allowed, pthread_cancel
-	     is not guaranteed to be async-safe.  */
-	  int val;
-	  val = INTERNAL_SYSCALL (tgkill, err, 3,
-				  THREAD_GETMEM (THREAD_SELF, pid), pd->tid,
-				  SIGCANCEL);
+	  pid_t pid = getpid ();
 
+	  INTERNAL_SYSCALL_DECL (err);
+	  int val = INTERNAL_SYSCALL_CALL (tgkill, err, pid, pd->tid,
+					   SIGCANCEL);
 	  if (INTERNAL_SYSCALL_ERROR_P (val, err))
 	    result = INTERNAL_SYSCALL_ERRNO (val, err);
 #else
diff --git a/nptl/pthread_getattr_np.c b/nptl/pthread_getattr_np.c
index fb906f0..32d7484 100644
--- a/nptl/pthread_getattr_np.c
+++ b/nptl/pthread_getattr_np.c
@@ -68,7 +68,6 @@ pthread_getattr_np (pthread_t thread_id, pthread_attr_t *attr)
     {
       /* No stack information available.  This must be for the initial
 	 thread.  Get the info in some magical way.  */
-      assert (abs (thread->pid) == thread->tid);
 
       /* Stack size limit.  */
       struct rlimit rl;
diff --git a/nptl_db/structs.def b/nptl_db/structs.def
index a9b621b..1cb6a46 100644
--- a/nptl_db/structs.def
+++ b/nptl_db/structs.def
@@ -48,7 +48,6 @@ DB_STRUCT (pthread)
 DB_STRUCT_FIELD (pthread, list)
 DB_STRUCT_FIELD (pthread, report_events)
 DB_STRUCT_FIELD (pthread, tid)
-DB_STRUCT_FIELD (pthread, pid)
 DB_STRUCT_FIELD (pthread, start_routine)
 DB_STRUCT_FIELD (pthread, cancelhandling)
 DB_STRUCT_FIELD (pthread, schedpolicy)
diff --git a/nptl_db/td_ta_thr_iter.c b/nptl_db/td_ta_thr_iter.c
index a990fed..9e50599 100644
--- a/nptl_db/td_ta_thr_iter.c
+++ b/nptl_db/td_ta_thr_iter.c
@@ -76,48 +76,28 @@ iterate_thread_list (td_thragent_t *ta, td_thr_iter_f *callback,
       if (ps_pdread (ta->ph, addr, copy, ta->ta_sizeof_pthread) != PS_OK)
 	return TD_ERR;
 
-      /* Verify that this thread's pid field matches the child PID.
-	 If its pid field is negative, it's about to do a fork or it
-	 is the sole thread in a fork child.  */
-      psaddr_t pid;
-      err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, pid, 0);
-      if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
-	{
-	  if (-(pid_t) (uintptr_t) pid == match_pid)
-	    /* It is about to do a fork, but is really still the parent PID.  */
-	    pid = (psaddr_t) (uintptr_t) match_pid;
-	  else
-	    /* It must be a fork child, whose new PID is in the tid field.  */
-	    err = DB_GET_FIELD_LOCAL (pid, ta, copy, pthread, tid, 0);
-	}
+      err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
+				schedpolicy, 0);
       if (err != TD_OK)
 	break;
+      err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
+				schedparam_sched_priority, 0);
+      if (err != TD_OK)
+	break;
+
+      /* Now test whether this thread matches the specified conditions.  */
 
-      if ((pid_t) (uintptr_t) pid == match_pid)
+      /* Only if the priority level is as high or higher.  */
+      int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
+		       ? 0 : (uintptr_t) schedprio);
+      if (descr_pri >= ti_pri)
 	{
-	  err = DB_GET_FIELD_LOCAL (schedpolicy, ta, copy, pthread,
-				    schedpolicy, 0);
-	  if (err != TD_OK)
-	    break;
-	  err = DB_GET_FIELD_LOCAL (schedprio, ta, copy, pthread,
-				    schedparam_sched_priority, 0);
-	  if (err != TD_OK)
-	    break;
-
-	  /* Now test whether this thread matches the specified conditions.  */
-
-	  /* Only if the priority level is as high or higher.  */
-	  int descr_pri = ((uintptr_t) schedpolicy == SCHED_OTHER
-			   ? 0 : (uintptr_t) schedprio);
-	  if (descr_pri >= ti_pri)
-	    {
-	      /* Yep, it matches.  Call the callback function.  */
-	      td_thrhandle_t th;
-	      th.th_ta_p = (td_thragent_t *) ta;
-	      th.th_unique = addr;
-	      if (callback (&th, cbdata_p) != 0)
-		return TD_DBERR;
-	    }
+	  /* Yep, it matches.  Call the callback function.  */
+	  td_thrhandle_t th;
+	  th.th_ta_p = (td_thragent_t *) ta;
+	  th.th_unique = addr;
+	  if (callback (&th, cbdata_p) != 0)
+	    return TD_DBERR;
 	}
 
       /* Get the pointer to the next element.  */
diff --git a/nptl_db/td_thr_validate.c b/nptl_db/td_thr_validate.c
index f3c8a7b..9b89fec 100644
--- a/nptl_db/td_thr_validate.c
+++ b/nptl_db/td_thr_validate.c
@@ -80,28 +80,5 @@ td_thr_validate (const td_thrhandle_t *th)
 	err = TD_OK;
     }
 
-  if (err == TD_OK)
-    {
-      /* Verify that this is not a stale element in a fork child.  */
-      pid_t match_pid = ps_getpid (th->th_ta_p->ph);
-      psaddr_t pid;
-      err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique, pthread, pid, 0);
-      if (err == TD_OK && (pid_t) (uintptr_t) pid < 0)
-	{
-	  /* This was a thread that was about to fork, or it is the new sole
-	     thread in a fork child.  In the latter case, its tid was stored
-	     via CLONE_CHILD_SETTID and so is already the proper child PID.  */
-	  if (-(pid_t) (uintptr_t) pid == match_pid)
-	    /* It is about to do a fork, but is really still the parent PID.  */
-	    pid = (psaddr_t) (uintptr_t) match_pid;
-	  else
-	    /* It must be a fork child, whose new PID is in the tid field.  */
-	    err = DB_GET_FIELD (pid, th->th_ta_p, th->th_unique,
-				pthread, tid, 0);
-	}
-      if (err == TD_OK && (pid_t) (uintptr_t) pid != match_pid)
-	err = TD_NOTHR;
-    }
-
   return err;
 }
diff --git a/sysdeps/aarch64/nptl/tcb-offsets.sym b/sysdeps/aarch64/nptl/tcb-offsets.sym
index 0677aea..238647d 100644
--- a/sysdeps/aarch64/nptl/tcb-offsets.sym
+++ b/sysdeps/aarch64/nptl/tcb-offsets.sym
@@ -2,6 +2,5 @@
 #include <tls.h>
 
 PTHREAD_MULTIPLE_THREADS_OFFSET		offsetof (struct pthread, header.multiple_threads)
-PTHREAD_PID_OFFSET			offsetof (struct pthread, pid)
 PTHREAD_TID_OFFSET			offsetof (struct pthread, tid)
 PTHREAD_SIZEOF				sizeof (struct pthread)
diff --git a/sysdeps/alpha/nptl/tcb-offsets.sym b/sysdeps/alpha/nptl/tcb-offsets.sym
index c21a791..1005621 100644
--- a/sysdeps/alpha/nptl/tcb-offsets.sym
+++ b/sysdeps/alpha/nptl/tcb-offsets.sym
@@ -10,5 +10,4 @@
 #define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - sizeof(struct pthread))
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
diff --git a/sysdeps/arm/nptl/tcb-offsets.sym b/sysdeps/arm/nptl/tcb-offsets.sym
index 92cc441..bf9c0a1 100644
--- a/sysdeps/arm/nptl/tcb-offsets.sym
+++ b/sysdeps/arm/nptl/tcb-offsets.sym
@@ -7,5 +7,4 @@
 #define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - sizeof(struct pthread))
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
diff --git a/sysdeps/hppa/nptl/tcb-offsets.sym b/sysdeps/hppa/nptl/tcb-offsets.sym
index c2f326e..6e852f3 100644
--- a/sysdeps/hppa/nptl/tcb-offsets.sym
+++ b/sysdeps/hppa/nptl/tcb-offsets.sym
@@ -3,7 +3,6 @@
 
 RESULT			offsetof (struct pthread, result)
 TID			offsetof (struct pthread, tid)
-PID			offsetof (struct pthread, pid)
 CANCELHANDLING		offsetof (struct pthread, cancelhandling)
 CLEANUP_JMP_BUF		offsetof (struct pthread, cleanup_jmp_buf)
 MULTIPLE_THREADS_OFFSET	offsetof (struct pthread, header.multiple_threads)
@@ -14,6 +13,5 @@ MUTEX_FUTEX		offsetof (pthread_mutex_t, __data.__lock)
 -- This way we get the offset of a member in the struct pthread that
 -- preceeds the thread pointer (which points to the dtv).
 #define thread_offsetof(mem)    (unsigned int)(offsetof(struct pthread, mem) - sizeof(struct pthread))
-PID_THREAD_OFFSET		thread_offsetof (pid)
 TID_THREAD_OFFSET		thread_offsetof (tid)
 MULTIPLE_THREADS_THREAD_OFFSET	thread_offsetof (header.multiple_threads)
diff --git a/sysdeps/i386/nptl/tcb-offsets.sym b/sysdeps/i386/nptl/tcb-offsets.sym
index 7bdf161..695a810 100644
--- a/sysdeps/i386/nptl/tcb-offsets.sym
+++ b/sysdeps/i386/nptl/tcb-offsets.sym
@@ -4,7 +4,6 @@
 
 RESULT			offsetof (struct pthread, result)
 TID			offsetof (struct pthread, tid)
-PID			offsetof (struct pthread, pid)
 CANCELHANDLING		offsetof (struct pthread, cancelhandling)
 CLEANUP_JMP_BUF		offsetof (struct pthread, cleanup_jmp_buf)
 MULTIPLE_THREADS_OFFSET	offsetof (tcbhead_t, multiple_threads)
diff --git a/sysdeps/ia64/nptl/tcb-offsets.sym b/sysdeps/ia64/nptl/tcb-offsets.sym
index e1707ab..b01f712 100644
--- a/sysdeps/ia64/nptl/tcb-offsets.sym
+++ b/sysdeps/ia64/nptl/tcb-offsets.sym
@@ -1,7 +1,6 @@
 #include <sysdep.h>
 #include <tls.h>
 
-PID			offsetof (struct pthread, pid) - TLS_PRE_TCB_SIZE
 TID			offsetof (struct pthread, tid) - TLS_PRE_TCB_SIZE
 MULTIPLE_THREADS_OFFSET offsetof (struct pthread, header.multiple_threads) - TLS_PRE_TCB_SIZE
 SYSINFO_OFFSET		offsetof (tcbhead_t, __private)
diff --git a/sysdeps/m68k/nptl/tcb-offsets.sym b/sysdeps/m68k/nptl/tcb-offsets.sym
index b1bba65..241fb8b 100644
--- a/sysdeps/m68k/nptl/tcb-offsets.sym
+++ b/sysdeps/m68k/nptl/tcb-offsets.sym
@@ -7,5 +7,4 @@
 #define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
diff --git a/sysdeps/microblaze/nptl/tcb-offsets.sym b/sysdeps/microblaze/nptl/tcb-offsets.sym
index 18afbee..614f0df 100644
--- a/sysdeps/microblaze/nptl/tcb-offsets.sym
+++ b/sysdeps/microblaze/nptl/tcb-offsets.sym
@@ -7,5 +7,4 @@
 #define thread_offsetof(mem)	(long)(offsetof (struct pthread, mem) - sizeof (struct pthread))
 
 MULTIPLE_THREADS_OFFSET	thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
diff --git a/sysdeps/mips/nptl/tcb-offsets.sym b/sysdeps/mips/nptl/tcb-offsets.sym
index e0e71dc..9ea25b9 100644
--- a/sysdeps/mips/nptl/tcb-offsets.sym
+++ b/sysdeps/mips/nptl/tcb-offsets.sym
@@ -7,5 +7,4 @@
 #define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
diff --git a/sysdeps/nios2/nptl/tcb-offsets.sym b/sysdeps/nios2/nptl/tcb-offsets.sym
index d9ae952..3cd8d98 100644
--- a/sysdeps/nios2/nptl/tcb-offsets.sym
+++ b/sysdeps/nios2/nptl/tcb-offsets.sym
@@ -9,6 +9,5 @@
 # define thread_offsetof(mem)   ((ptrdiff_t) THREAD_SELF + offsetof (struct pthread, mem))
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
 POINTER_GUARD			(offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index 616d897..02ff793 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -135,12 +135,6 @@ __libc_fork (void)
   pid_t ppid = THREAD_GETMEM (THREAD_SELF, tid);
 #endif
 
-  /* We need to prevent the getpid() code to update the PID field so
-     that, if a signal arrives in the child very early and the signal
-     handler uses getpid(), the value returned is correct.  */
-  pid_t parentpid = THREAD_GETMEM (THREAD_SELF, pid);
-  THREAD_SETMEM (THREAD_SELF, pid, -parentpid);
-
 #ifdef ARCH_FORK
   pid = ARCH_FORK ();
 #else
@@ -159,9 +153,6 @@ __libc_fork (void)
       if (__fork_generation_pointer != NULL)
 	*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;
 
-      /* Adjust the PID field for the new process.  */
-      THREAD_SETMEM (self, pid, THREAD_GETMEM (self, tid));
-
 #if HP_TIMING_AVAIL
       /* The CPU clock of the thread and process have to be set to zero.  */
       hp_timing_t now;
@@ -233,9 +224,6 @@ __libc_fork (void)
     {
       assert (THREAD_GETMEM (THREAD_SELF, tid) == ppid);
 
-      /* Restore the PID value.  */
-      THREAD_SETMEM (THREAD_SELF, pid, parentpid);
-
       /* Release acquired locks in the multi-threaded case.  */
       if (multiple_threads)
 	{
diff --git a/sysdeps/powerpc/nptl/tcb-offsets.sym b/sysdeps/powerpc/nptl/tcb-offsets.sym
index f580e69..7c9fd33 100644
--- a/sysdeps/powerpc/nptl/tcb-offsets.sym
+++ b/sysdeps/powerpc/nptl/tcb-offsets.sym
@@ -13,7 +13,6 @@
 #if TLS_MULTIPLE_THREADS_IN_TCB
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
 #endif
-PID				thread_offsetof (pid)
 TID				thread_offsetof (tid)
 POINTER_GUARD			(offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
 TAR_SAVE			(offsetof (tcbhead_t, tar_save) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
diff --git a/sysdeps/s390/nptl/tcb-offsets.sym b/sysdeps/s390/nptl/tcb-offsets.sym
index 9cfae21..9c1c01f 100644
--- a/sysdeps/s390/nptl/tcb-offsets.sym
+++ b/sysdeps/s390/nptl/tcb-offsets.sym
@@ -3,5 +3,4 @@
 
 MULTIPLE_THREADS_OFFSET		offsetof (tcbhead_t, multiple_threads)
 STACK_GUARD			offsetof (tcbhead_t, stack_guard)
-PID				offsetof (struct pthread, pid)
 TID				offsetof (struct pthread, tid)
diff --git a/sysdeps/sh/nptl/tcb-offsets.sym b/sysdeps/sh/nptl/tcb-offsets.sym
index ac63b5b..4963e15 100644
--- a/sysdeps/sh/nptl/tcb-offsets.sym
+++ b/sysdeps/sh/nptl/tcb-offsets.sym
@@ -4,7 +4,6 @@
 
 RESULT			offsetof (struct pthread, result)
 TID			offsetof (struct pthread, tid)
-PID			offsetof (struct pthread, pid)
 CANCELHANDLING		offsetof (struct pthread, cancelhandling)
 CLEANUP_JMP_BUF		offsetof (struct pthread, cleanup_jmp_buf)
 MULTIPLE_THREADS_OFFSET	offsetof (struct pthread, header.multiple_threads)
diff --git a/sysdeps/sparc/nptl/tcb-offsets.sym b/sysdeps/sparc/nptl/tcb-offsets.sym
index 923af8a..f75d020 100644
--- a/sysdeps/sparc/nptl/tcb-offsets.sym
+++ b/sysdeps/sparc/nptl/tcb-offsets.sym
@@ -3,5 +3,4 @@
 
 MULTIPLE_THREADS_OFFSET		offsetof (tcbhead_t, multiple_threads)
 POINTER_GUARD			offsetof (tcbhead_t, pointer_guard)
-PID				offsetof (struct pthread, pid)
 TID				offsetof (struct pthread, tid)
diff --git a/sysdeps/tile/nptl/tcb-offsets.sym b/sysdeps/tile/nptl/tcb-offsets.sym
index 6740bc9..0147ffa 100644
--- a/sysdeps/tile/nptl/tcb-offsets.sym
+++ b/sysdeps/tile/nptl/tcb-offsets.sym
@@ -9,7 +9,6 @@
 #define thread_offsetof(mem)	(long)(offsetof(struct pthread, mem) - TLS_TCB_OFFSET - TLS_PRE_TCB_SIZE)
 
 MULTIPLE_THREADS_OFFSET		thread_offsetof (header.multiple_threads)
-PID_OFFSET			thread_offsetof (pid)
 TID_OFFSET			thread_offsetof (tid)
 POINTER_GUARD			(offsetof (tcbhead_t, pointer_guard) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
 FEEDBACK_DATA_OFFSET		(offsetof (tcbhead_t, feedback_data) - TLS_TCB_OFFSET - sizeof (tcbhead_t))
diff --git a/sysdeps/unix/sysv/linux/aarch64/clone.S b/sysdeps/unix/sysv/linux/aarch64/clone.S
index 76baa7a..96482e5 100644
--- a/sysdeps/unix/sysv/linux/aarch64/clone.S
+++ b/sysdeps/unix/sysv/linux/aarch64/clone.S
@@ -72,16 +72,6 @@ thread_start:
 	cfi_undefined (x30)
 	mov	x29, 0
 
-	tbnz	x11, #CLONE_VM_BIT, 1f
-
-	mov	x8, #SYS_ify(getpid)
-	svc	0x0
-	mrs	x1, tpidr_el0
-	sub	x1, x1, #PTHREAD_SIZEOF
-	str	w0, [x1, #PTHREAD_PID_OFFSET]
-	str	w0, [x1, #PTHREAD_TID_OFFSET]
-1:
-
 	/* Pick the function arg and execute.  */
 	mov	x0, x12
 	blr	x10
diff --git a/sysdeps/unix/sysv/linux/aarch64/vfork.S b/sysdeps/unix/sysv/linux/aarch64/vfork.S
index 577895e..aeed0b2 100644
--- a/sysdeps/unix/sysv/linux/aarch64/vfork.S
+++ b/sysdeps/unix/sysv/linux/aarch64/vfork.S
@@ -27,27 +27,10 @@
 
 ENTRY (__vfork)
 
-	/* Save the TCB-cached PID away in w3, and then negate the TCB
-           field.  But if it's zero, set it to 0x80000000 instead.  See
-           raise.c for the logic that relies on this value.  */
-	mrs	x2, tpidr_el0
-	sub	x2, x2, #PTHREAD_SIZEOF
-	ldr	w3, [x2, #PTHREAD_PID_OFFSET]
-	mov	w1, #0x80000000
-	negs	w0, w3
-	csel	w0, w1, w0, eq
-	str	w0, [x2, #PTHREAD_PID_OFFSET]
-
 	mov	x0, #0x4111	/* CLONE_VM | CLONE_VFORK | SIGCHLD */
 	mov	x1, sp
 	DO_CALL (clone, 2)
 
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	cbz	x0, 1f
-	str	w3, [x2, #PTHREAD_PID_OFFSET]
-1:
 	cmn	x0, #4095
 	b.cs    .Lsyscall_error
 	RET
diff --git a/sysdeps/unix/sysv/linux/alpha/clone.S b/sysdeps/unix/sysv/linux/alpha/clone.S
index 6a3154f..2757bf2 100644
--- a/sysdeps/unix/sysv/linux/alpha/clone.S
+++ b/sysdeps/unix/sysv/linux/alpha/clone.S
@@ -91,13 +91,6 @@ thread_start:
 	cfi_def_cfa_register(fp)
 	cfi_undefined(ra)
 
-	/* Check and see if we need to reset the PID.  */
-	ldq	t0, 16(sp)
-	lda	t1, CLONE_VM
-	and	t0, t1, t2
-	beq	t2, 2f
-1:
-
 	/* Load up the arguments.  */
 	ldq	pv, 0(sp)
 	ldq	a0, 8(sp)
@@ -120,15 +113,6 @@ thread_start:
 	halt
 
 	.align	4
-2:
-	rduniq
-	mov	v0, s0
-	lda	v0, __NR_getxpid
-	callsys
-3:
-	stl	v0, PID_OFFSET(s0)
-	stl	v0, TID_OFFSET(s0)
-	br	1b
 	cfi_endproc
 	.end thread_start
 
diff --git a/sysdeps/unix/sysv/linux/alpha/vfork.S b/sysdeps/unix/sysv/linux/alpha/vfork.S
index 9fc199a..e5f7ed0 100644
--- a/sysdeps/unix/sysv/linux/alpha/vfork.S
+++ b/sysdeps/unix/sysv/linux/alpha/vfork.S
@@ -25,24 +25,9 @@ ENTRY(__libc_vfork)
 	rduniq
 	mov	v0, a1
 
-	/* Save the TCB-cached PID away in A2, and then negate the TCB
-           field.  But if it's zero, set it to 0x80000000 instead.  See
-           raise.c for the logic that relies on this value.  */
-	ldl	a2, PID_OFFSET(v0)
-	ldah	t0, -0x8000
-	negl	a2, t1
-	cmovne	a2, t1, t0
-	stl	t0, PID_OFFSET(v0);
-
 	lda	v0, SYS_ify(vfork)
 	call_pal PAL_callsys
 
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	beq	v0, 1f
-	stl	a2, PID_OFFSET(a1)
-1:
 	/* Normal error check and return.  */
 	bne	a3, SYSCALL_ERROR_LABEL
 	ret
diff --git a/sysdeps/unix/sysv/linux/arm/clone.S b/sysdeps/unix/sysv/linux/arm/clone.S
index 7ff6818..4c6325d 100644
--- a/sysdeps/unix/sysv/linux/arm/clone.S
+++ b/sysdeps/unix/sysv/linux/arm/clone.S
@@ -70,16 +70,6 @@ PSEUDO_END (__clone)
 1:
 	.fnstart
 	.cantunwind
-	tst	ip, #CLONE_VM
-	bne	2f
-	GET_TLS (lr)
-	mov	r1, r0
-	ldr	r7, =SYS_ify(getpid)
-	swi	0x0
-	NEGOFF_ADJ_BASE (r1, TID_OFFSET)
-	str	r0, NEGOFF_OFF1 (r1, TID_OFFSET)
-	str	r0, NEGOFF_OFF2 (r1, PID_OFFSET, TID_OFFSET)
-2:
 	@ pick the function arg and call address off the stack and execute
 	ldr	r0, [sp, #4]
 	ldr 	ip, [sp], #8
diff --git a/sysdeps/unix/sysv/linux/arm/vfork.S b/sysdeps/unix/sysv/linux/arm/vfork.S
index 500f5ca..794372e 100644
--- a/sysdeps/unix/sysv/linux/arm/vfork.S
+++ b/sysdeps/unix/sysv/linux/arm/vfork.S
@@ -28,16 +28,6 @@
    and the process ID of the new process to the old process.  */
 
 ENTRY (__vfork)
-	/* Save the PID value.  */
-	GET_TLS (r2)
-	NEGOFF_ADJ_BASE2 (r2, r0, PID_OFFSET) /* Save the TLS addr in r2.  */
-	ldr	r3, NEGOFF_OFF1 (r2, PID_OFFSET) /* Load the saved PID.  */
-	rsbs	r0, r3, #0		/* Negate it, and test for zero.  */
-	/* Use 0x80000000 if it was 0.  See raise.c for how this is used.  */
-	it	eq
-	moveq	r0, #0x80000000
-	str	r0, NEGOFF_OFF1 (r2, PID_OFFSET) /* Store the temp PID.  */
-
 	/* The DO_CALL macro saves r7 on the stack, to enable generation
 	   of ARM unwind info.  Since the stack is initially shared between
 	   parent and child of vfork, that saved value could be corrupted.
@@ -57,11 +47,6 @@ ENTRY (__vfork)
 	mov	r7, ip
 	cfi_restore (r7)
 
-	/* Restore the old PID value in the parent.  */
-	cmp	r0, #0		/* If we are the parent... */
-	it	ne
-	strne	r3, NEGOFF_OFF1 (r2, PID_OFFSET) /* restore the saved PID.  */
-
 	cmn	a1, #4096
 	it	cc
 	RETINSTR(cc, lr)
diff --git a/sysdeps/unix/sysv/linux/createthread.c b/sysdeps/unix/sysv/linux/createthread.c
index 6d32cec..ec86f50 100644
--- a/sysdeps/unix/sysv/linux/createthread.c
+++ b/sysdeps/unix/sysv/linux/createthread.c
@@ -128,10 +128,10 @@ create_thread (struct pthread *pd, const struct pthread_attr *attr,
 	      /* The operation failed.  We have to kill the thread.
 		 We let the normal cancellation mechanism do the work.  */
 
+	      pid_t pid = __getpid ();
 	      INTERNAL_SYSCALL_DECL (err2);
-	      (void) INTERNAL_SYSCALL (tgkill, err2, 3,
-				       THREAD_GETMEM (THREAD_SELF, pid),
-				       pd->tid, SIGCANCEL);
+	      (void) INTERNAL_SYSCALL_CALL (tgkill, err2, pid, pd->tid,
+					    SIGCANCEL);
 
 	      return INTERNAL_SYSCALL_ERRNO (res, err);
 	    }
diff --git a/sysdeps/unix/sysv/linux/getpid.c b/sysdeps/unix/sysv/linux/getpid.c
deleted file mode 100644
index 1124549..0000000
--- a/sysdeps/unix/sysv/linux/getpid.c
+++ /dev/null
@@ -1,64 +0,0 @@
-/* Copyright (C) 2003-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@redhat.com>, 2003.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <unistd.h>
-#include <tls.h>
-#include <sysdep.h>
-
-
-#if IS_IN (libc)
-static inline __attribute__((always_inline)) pid_t really_getpid (pid_t oldval);
-
-static inline __attribute__((always_inline)) pid_t
-really_getpid (pid_t oldval)
-{
-  if (__glibc_likely (oldval == 0))
-    {
-      pid_t selftid = THREAD_GETMEM (THREAD_SELF, tid);
-      if (__glibc_likely (selftid != 0))
-	return selftid;
-    }
-
-  INTERNAL_SYSCALL_DECL (err);
-  pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
-
-  /* We do not set the PID field in the TID here since we might be
-     called from a signal handler while the thread executes fork.  */
-  if (oldval == 0)
-    THREAD_SETMEM (THREAD_SELF, tid, result);
-  return result;
-}
-#endif
-
-pid_t
-__getpid (void)
-{
-#if !IS_IN (libc)
-  INTERNAL_SYSCALL_DECL (err);
-  pid_t result = INTERNAL_SYSCALL (getpid, err, 0);
-#else
-  pid_t result = THREAD_GETMEM (THREAD_SELF, pid);
-  if (__glibc_unlikely (result <= 0))
-    result = really_getpid (result);
-#endif
-  return result;
-}
-
-libc_hidden_def (__getpid)
-weak_alias (__getpid, getpid)
-libc_hidden_def (getpid)
diff --git a/sysdeps/unix/sysv/linux/hppa/clone.S b/sysdeps/unix/sysv/linux/hppa/clone.S
index 3d037f1..25fcd49 100644
--- a/sysdeps/unix/sysv/linux/hppa/clone.S
+++ b/sysdeps/unix/sysv/linux/hppa/clone.S
@@ -132,18 +132,6 @@ ENTRY(__clone)
 	ldwm	-64(%sp), %r4
 
 .LthreadStart:
-# define CLONE_VM_BIT		23	/* 0x00000100  */
-	/* Load original clone flags.
-	   If CLONE_VM was passed, don't modify PID/TID.
-	   Otherwise store the result of getpid to PID/TID.  */
-	ldw	-56(%sp), %r26
-	bb,<,n	%r26, CLONE_VM_BIT, 1f
-	ble     0x100(%sr2, %r0)
-	ldi	__NR_getpid, %r20
-	mfctl	%cr27, %r26
-	stw	%ret0, PID_THREAD_OFFSET(%r26)
-	stw	%ret0, TID_THREAD_OFFSET(%r26)
-1:
 	/* Load up the arguments.  */
 	ldw	-60(%sp), %arg0
 	ldw     -64(%sp), %r22
diff --git a/sysdeps/unix/sysv/linux/hppa/pt-vfork.S b/sysdeps/unix/sysv/linux/hppa/pt-vfork.S
index df53236..4684048 100644
--- a/sysdeps/unix/sysv/linux/hppa/pt-vfork.S
+++ b/sysdeps/unix/sysv/linux/hppa/pt-vfork.S
@@ -25,26 +25,6 @@
    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
    and the process ID of the new process to the old process.  */
 
-/* Load the thread register.
-   Load the saved PID value.
-   Negate the value.
-   Store the temporary PID. */
-#define SAVE_PID							\
-	mfctl %cr27, %r26				ASM_LINE_SEP	\
-	ldw PID_THREAD_OFFSET(%r26),%r1			ASM_LINE_SEP    \
-	sub %r0,%r1,%r1					ASM_LINE_SEP    \
-	stw %r1,PID_THREAD_OFFSET(%r26)			ASM_LINE_SEP
-/* If we are the parent...
-   Get the thread pointer.
-   Load the saved PID.
-   Negate the value (got back original)
-   Restore the PID. */
-#define RESTORE_PID							\
-	cmpb,=,n %r0,%ret0,.Lthread_start		ASM_LINE_SEP	\
-	mfctl %cr27, %r26				ASM_LINE_SEP	\
-	ldw PID_THREAD_OFFSET(%r26),%r1			ASM_LINE_SEP	\
-	sub %r0,%r1,%r1					ASM_LINE_SEP	\
-	stw %r1,PID_THREAD_OFFSET(%r26)			ASM_LINE_SEP	\
 .Lthread_start:						ASM_LINE_SEP
 
 	/* r26, r25, r24, r23 are free since vfork has no arguments */
@@ -58,16 +38,10 @@ ENTRY(__vfork)
 	copy	%r19, %r25	/* parent */
 #endif
 
-	/* Save the process PID */
-	SAVE_PID
-
 	/* Syscall saves and restores all register states */
 	ble	0x100(%sr2,%r0)
 	ldi	__NR_vfork,%r20
 
-	/* Conditionally restore the PID */
-	RESTORE_PID
-
 	/* Check for error */
 	ldi	-4096,%r1
 	comclr,>>= %r1,%ret0,%r0        /* Note: unsigned compare. */
diff --git a/sysdeps/unix/sysv/linux/i386/clone.S b/sysdeps/unix/sysv/linux/i386/clone.S
index 25f2a9c..feae504 100644
--- a/sysdeps/unix/sysv/linux/i386/clone.S
+++ b/sysdeps/unix/sysv/linux/i386/clone.S
@@ -107,9 +107,6 @@ L(thread_start):
 	cfi_undefined (eip);
 	/* Note: %esi is zero.  */
 	movl	%esi,%ebp	/* terminate the stack frame */
-	testl	$CLONE_VM, %edi
-	je	L(newpid)
-L(haspid):
 	call	*%ebx
 #ifdef PIC
 	call	L(here)
@@ -121,18 +118,6 @@ L(here):
 	movl	$SYS_ify(exit), %eax
 	ENTER_KERNEL
 
-	.subsection 2
-L(newpid):
-	movl	$SYS_ify(getpid), %eax
-	ENTER_KERNEL
-L(nomoregetpid):
-	movl	%eax, %gs:PID
-	movl	%eax, %gs:TID
-	jmp	L(haspid)
-	.previous
-	cfi_endproc;
-
-	cfi_startproc
 PSEUDO_END (__clone)
 
 libc_hidden_def (__clone)
diff --git a/sysdeps/unix/sysv/linux/i386/vfork.S b/sysdeps/unix/sysv/linux/i386/vfork.S
index 7a1d337..a865de2 100644
--- a/sysdeps/unix/sysv/linux/i386/vfork.S
+++ b/sysdeps/unix/sysv/linux/i386/vfork.S
@@ -34,17 +34,6 @@ ENTRY (__vfork)
 	cfi_adjust_cfa_offset (-4)
 	cfi_register (%eip, %ecx)
 
-	/* Save the TCB-cached PID away in %edx, and then negate the TCB
-           field.  But if it's zero, set it to 0x80000000 instead.  See
-           raise.c for the logic that relies on this value.  */
-	movl	%gs:PID, %edx
-	movl	%edx, %eax
-	negl	%eax
-	jne	1f
-	movl	$0x80000000, %eax
-1:	movl	%eax, %gs:PID
-
-
 	/* Stuff the syscall number in EAX and enter into the kernel.  */
 	movl	$SYS_ify (vfork), %eax
 	int	$0x80
@@ -55,14 +44,6 @@ ENTRY (__vfork)
 	pushl	%ecx
 	cfi_adjust_cfa_offset (4)
 
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	testl	%eax, %eax
-	je	1f
-	movl	%edx, %gs:PID
-1:
-
 	cmpl	$-4095, %eax
 	/* Branch forward if it failed.  */
 	jae	SYSCALL_ERROR_LABEL
diff --git a/sysdeps/unix/sysv/linux/ia64/clone2.S b/sysdeps/unix/sysv/linux/ia64/clone2.S
index b4cfdfc..e637b6d 100644
--- a/sysdeps/unix/sysv/linux/ia64/clone2.S
+++ b/sysdeps/unix/sysv/linux/ia64/clone2.S
@@ -67,19 +67,7 @@ ENTRY(__clone2)
 (CHILD)	mov loc0=gp
 (PARENT) ret
 	;;
-	tbit.nz p6,p0=in3,8	/* CLONE_VM */
-(p6)	br.cond.dptk 1f
-	;;
-	mov r15=SYS_ify (getpid)
-(p7)	break __BREAK_SYSCALL
-	;;
-	add r9=PID,r13
-	add r10=TID,r13
-	;;
-	st4 [r9]=r8
-	st4 [r10]=r8
-	;;
-1:	ld8 out1=[in0],8	/* Retrieve code pointer.	*/
+	ld8 out1=[in0],8	/* Retrieve code pointer.	*/
 	mov out0=in4		/* Pass proper argument	to fn */
 	;;
 	ld8 gp=[in0]		/* Load function gp.		*/
diff --git a/sysdeps/unix/sysv/linux/ia64/vfork.S b/sysdeps/unix/sysv/linux/ia64/vfork.S
index 9154d7c..84bfdd5 100644
--- a/sysdeps/unix/sysv/linux/ia64/vfork.S
+++ b/sysdeps/unix/sysv/linux/ia64/vfork.S
@@ -33,32 +33,12 @@ ENTRY (__libc_vfork)
 	.prologue	// work around a GAS bug which triggers if
 	.body		// first .prologue is not at the beginning of proc.
 	alloc r2=ar.pfs,0,0,2,0
-	adds r14=PID,r13
-	;;
-	ld4 r16=[r14]
-	;;
-	sub r15=0,r16
-	cmp.eq p6,p0=0,r16
-	;;
-(p6)	movl r15=0x80000000
 	mov out0=CLONE_VM+CLONE_VFORK+SIGCHLD
 	mov out1=0		/* Standard sp value.			*/
 	;;
-	st4 [r14]=r15
 	DO_CALL (SYS_ify (clone))
 	cmp.eq p6,p0=0,r8
-	adds r14=PID,r13
 (p6)	br.cond.dptk 1f
-	;;
-	ld4 r15=[r14]
-	;;
-	extr.u r16=r15,0,31
-	;;
-	cmp.eq p0,p6=0,r16
-	;;
-(p6)	sub r16=0,r15
-	;;
-	st4 [r14]=r16
 1:
 	cmp.eq p6,p0=-1,r10
 (p6)	br.cond.spnt.few __syscall_error
diff --git a/sysdeps/unix/sysv/linux/m68k/clone.S b/sysdeps/unix/sysv/linux/m68k/clone.S
index 3a82844..630a292 100644
--- a/sysdeps/unix/sysv/linux/m68k/clone.S
+++ b/sysdeps/unix/sysv/linux/m68k/clone.S
@@ -98,19 +98,6 @@ ENTRY (__clone)
 	cfi_startproc
 	cfi_undefined (pc)	/* Mark end of stack */
 	subl	%fp, %fp	/* terminate the stack frame */
-	/* Check and see if we need to reset the PID.  */
-	andl	#CLONE_VM, %d1
-	jne	1f
-	movel	#SYS_ify (getpid), %d0
-	trap	#0
-	movel	%a0, -(%sp)
-	movel	%d0, -(%sp)
-	bsrl	__m68k_read_tp@PLTPC
-	movel	(%sp)+, %d0
-	movel	%d0, PID_OFFSET(%a0)
-	movel	%d0, TID_OFFSET(%a0)
-	movel	(%sp)+, %a0
-1:
 	jsr	(%a0)
 	movel	%d0, %d1
 	movel	#SYS_ify (exit), %d0
diff --git a/sysdeps/unix/sysv/linux/m68k/vfork.S b/sysdeps/unix/sysv/linux/m68k/vfork.S
index 1625a7b..e274793 100644
--- a/sysdeps/unix/sysv/linux/m68k/vfork.S
+++ b/sysdeps/unix/sysv/linux/m68k/vfork.S
@@ -28,18 +28,6 @@
 
 ENTRY (__vfork)
 
-	/* Save the TCB-cached PID away in %d1, and then negate the TCB
-	   field.  But if it's zero, set it to 0x80000000 instead.  See
-	   raise.c for the logic that relies on this value.  */
-	jbsr	__m68k_read_tp@PLTPC
-	movel	%a0, %a1
-	movel	PID_OFFSET(%a1), %d0
-	movel	%d0, %d1
-	negl	%d0
-	jne	1f
-	movel	#0x80000000, %d0
-1:	movel	%d0, PID_OFFSET(%a1)
-
 	/* Pop the return PC value into A0.  */
 	movel	%sp@+, %a0
 	cfi_adjust_cfa_offset (-4)
@@ -49,14 +37,6 @@ ENTRY (__vfork)
 	movel	#SYS_ify (vfork), %d0
 	trap	#0
 
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	tstl	%d0
-	jeq	1f
-	movel	%d1, PID_OFFSET(%a1)
-1:
-
 	tstl	%d0
 	jmi	.Lerror		/* Branch forward if it failed.  */
 
diff --git a/sysdeps/unix/sysv/linux/mips/clone.S b/sysdeps/unix/sysv/linux/mips/clone.S
index 39634c5..7ae65ef 100644
--- a/sysdeps/unix/sysv/linux/mips/clone.S
+++ b/sysdeps/unix/sysv/linux/mips/clone.S
@@ -130,11 +130,6 @@ L(thread_start):
 	SAVE_GP (GPOFF)
 	/* The stackframe has been created on entry of clone().  */
 
-	/* Check and see if we need to reset the PID.  */
-	and	a1,a0,CLONE_VM
-	beqz	a1,L(restore_pid)
-L(donepid):
-
 	/* Restore the arg for user's function.  */
 	PTR_L		t9,0(sp)	/* Function pointer.  */
 	PTR_L		a0,PTRSIZE(sp)	/* Argument pointer.  */
@@ -151,14 +146,6 @@ L(donepid):
 	jal		_exit
 #endif
 
-L(restore_pid):
-	li		v0,__NR_getpid
-	syscall
-	READ_THREAD_POINTER(v1)
-	INT_S		v0,PID_OFFSET(v1)
-	INT_S		v0,TID_OFFSET(v1)
-	b		L(donepid)
-
 	END(__thread_start)
 
 libc_hidden_def (__clone)
diff --git a/sysdeps/unix/sysv/linux/mips/vfork.S b/sysdeps/unix/sysv/linux/mips/vfork.S
index 1867c86..0b9244b 100644
--- a/sysdeps/unix/sysv/linux/mips/vfork.S
+++ b/sysdeps/unix/sysv/linux/mips/vfork.S
@@ -60,14 +60,6 @@ NESTED(__libc_vfork,FRAMESZ,sp)
 	PTR_ADDU	sp, FRAMESZ
 	cfi_adjust_cfa_offset (-FRAMESZ)
 
-	/* Save the PID value.  */
-	READ_THREAD_POINTER(v1)	   /* Get the thread pointer.  */
-	lw	a2, PID_OFFSET(v1) /* Load the saved PID.  */
-	subu	a2, $0, a2	   /* Negate it.  */
-	bnez	a2, 1f		   /* If it was zero... */
-	lui	a2, 0x8000	   /* use 0x80000000 instead.  */
-1:	sw	a2, PID_OFFSET(v1) /* Store the temporary PID.  */
-
 	li		a0, 0x4112	/* CLONE_VM | CLONE_VFORK | SIGCHLD */
 	move		a1, sp
 
@@ -75,17 +67,6 @@ NESTED(__libc_vfork,FRAMESZ,sp)
 	li		v0,__NR_clone
 	syscall
 
-	/* Restore the old PID value in the parent.  */
-	beqz	v0, 1f		/* If we are the parent... */
-	READ_THREAD_POINTER(v1)	/* Get the thread pointer.  */
-	lw	a2, PID_OFFSET(v1) /* Load the saved PID.  */
-	subu	a2, $0, a2	   /* Re-negate it.  */
-	lui	a0, 0x8000	   /* Load 0x80000000... */
-	bne	a2, a0, 2f	   /* ... compare against it... */
-	li	a2, 0		   /* ... use 0 instead.  */
-2:	sw	a2, PID_OFFSET(v1) /* Restore the PID.  */
-1:
-
 	cfi_remember_state
 	bnez		a3,L(error)
 
diff --git a/sysdeps/unix/sysv/linux/nios2/clone.S b/sysdeps/unix/sysv/linux/nios2/clone.S
index 30b6e4a..c9fa00f 100644
--- a/sysdeps/unix/sysv/linux/nios2/clone.S
+++ b/sysdeps/unix/sysv/linux/nios2/clone.S
@@ -68,14 +68,6 @@ thread_start:
 	cfi_startproc
 	cfi_undefined (ra)
 
-	/* We expect the argument registers to be preserved across system
-	   calls and across task cloning, so flags should be in r4 here.  */
-	andi	r2, r4, CLONE_VM
-	bne	r2, zero, 2f
-        DO_CALL (getpid, 0)
-	stw	r2, PID_OFFSET(r23)
-	stw	r2, TID_OFFSET(r23)
-2:
 	ldw	r5, 4(sp)	/* Function pointer.  */
 	ldw	r4, 0(sp)	/* Argument pointer.  */
 	addi	sp, sp, 8
diff --git a/sysdeps/unix/sysv/linux/nios2/vfork.S b/sysdeps/unix/sysv/linux/nios2/vfork.S
index c1bb9c7..8997269 100644
--- a/sysdeps/unix/sysv/linux/nios2/vfork.S
+++ b/sysdeps/unix/sysv/linux/nios2/vfork.S
@@ -21,20 +21,10 @@
 
 ENTRY(__vfork)
 
-	ldw	r6, PID_OFFSET(r23)
-	sub	r7, zero, r6
-	bne	r7, zero, 2f
-	movhi	r7, %hi(0x80000000)
-2:
-	stw	r7, PID_OFFSET(r23)
-
 	movi	r4, 0x4111 /* (CLONE_VM | CLONE_VFORK | SIGCHLD) */
 	mov	r5, zero
 	DO_CALL (clone, 2)
 
-	beq	r2, zero, 1f
-	stw	r6, PID_OFFSET(r23)
-1:
 	bne	r7, zero, SYSCALL_ERROR_LABEL
 	ret
 
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
index bebadbf..49fe01e 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S
@@ -76,15 +76,6 @@ ENTRY (__clone)
 	crandc	cr1*4+eq,cr1*4+eq,cr0*4+so
 	bne-	cr1,L(parent)		/* The '-' is to minimise the race.  */
 
-	/* If CLONE_VM is set do not update the pid/tid field.  */
-	andi.	r0,r28,CLONE_VM
-	bne+	cr0,L(oldpid)
-
-	DO_CALL(SYS_ify(getpid))
-	stw	r3,TID(r2)
-	stw	r3,PID(r2)
-L(oldpid):
-
 	/* Call procedure.  */
 	mtctr	r30
 	mr	r3,r31
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S b/sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S
index edbc7de..0a72495 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc32/vfork.S
@@ -27,34 +27,8 @@
 
 ENTRY (__vfork)
 
-	/* Load the TCB-cached PID value and negates it. If It it is zero
-	   sets it to 0x800000.  And then sets its value again on TCB field.
-	   See raise.c for the logic that relies on this value.  */
-
-	lwz	r0,PID(r2)
-	cmpwi	cr0,r0,0
-	neg	r0,r0
-	bne-	cr0,1f
-	lis	r0,0x8000
-1:	stw	r0,PID(r2)
-
 	DO_CALL (SYS_ify (vfork))
 
-	cmpwi	cr1,r3,0
-	beqlr-	1
-
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	lwz	r0,PID(r2)
-	/* Cannot use clrlwi. here, because cr0 needs to be preserved
-	   until PSEUDO_RET.  */
-	clrlwi	r4,r0,1
-	cmpwi	cr1,r4,0
-	beq-	cr1,1f
-	neg	r4,r0
-1:	stw	r4,PID(r2)
-
 	PSEUDO_RET
 
 PSEUDO_END (__vfork)
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
index 7c59b9b..d8604f6 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S
@@ -78,15 +78,6 @@ ENTRY (__clone)
 	crandc	cr1*4+eq,cr1*4+eq,cr0*4+so
 	bne-	cr1,L(parent)		/* The '-' is to minimise the race.  */
 
-	/* If CLONE_VM is set do not update the pid/tid field.  */
-	rldicl.	r0,r29,56,63		/* flags & CLONE_VM.  */
-	bne+	cr0,L(oldpid)
-
-	DO_CALL(SYS_ify(getpid))
-	stw	r3,TID(r13)
-	stw	r3,PID(r13)
-L(oldpid):
-
 	std	r2,FRAME_TOC_SAVE(r1)
 	/* Call procedure.  */
 	PPC64_LOAD_FUNCPTR r30
diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S
index 3083ab7..6b4cf43 100644
--- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S
+++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/vfork.S
@@ -28,31 +28,8 @@
 ENTRY (__vfork)
 	CALL_MCOUNT 0
 
-	/* Load the TCB-cached PID value and negates it. If It it is zero
-	   sets it to 0x800000.  And then sets its value again on TCB field.
-	   See raise.c for the logic that relies on this value.  */
-	lwz	r0,PID(r13)
-	cmpwi	cr0,r0,0
-	neg	r0,r0
-	bne-	cr0,1f
-	lis	r0,0x8000
-1:	stw	r0,PID(r13)
-
 	DO_CALL (SYS_ify (vfork))
 
-	cmpwi	cr1,r3,0
-	beqlr-	1
-
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	lwz	r0,PID(r13)
-	clrlwi	r4,r0,1
-	cmpwi	cr1,r4,0
-	beq-	cr1,1f
-	neg	r4,r0
-1:	stw	r4,PID(r13)
-
 	PSEUDO_RET
 
 PSEUDO_END (__vfork)
diff --git a/sysdeps/unix/sysv/linux/pthread-pids.h b/sysdeps/unix/sysv/linux/pthread-pids.h
index d42bba0..618a5b1 100644
--- a/sysdeps/unix/sysv/linux/pthread-pids.h
+++ b/sysdeps/unix/sysv/linux/pthread-pids.h
@@ -26,5 +26,5 @@ static inline void
 __pthread_initialize_pids (struct pthread *pd)
 {
   INTERNAL_SYSCALL_DECL (err);
-  pd->pid = pd->tid = INTERNAL_SYSCALL (set_tid_address, err, 1, &pd->tid);
+  pd->tid = INTERNAL_SYSCALL_CALL (set_tid_address, err, &pd->tid);
 }
diff --git a/sysdeps/unix/sysv/linux/pthread_kill.c b/sysdeps/unix/sysv/linux/pthread_kill.c
index bcb3009..cc10997 100644
--- a/sysdeps/unix/sysv/linux/pthread_kill.c
+++ b/sysdeps/unix/sysv/linux/pthread_kill.c
@@ -21,6 +21,7 @@
 #include <pthreadP.h>
 #include <tls.h>
 #include <sysdep.h>
+#include <unistd.h>
 
 
 int
@@ -49,15 +50,9 @@ __pthread_kill (pthread_t threadid, int signo)
   /* We have a special syscall to do the work.  */
   INTERNAL_SYSCALL_DECL (err);
 
-  /* One comment: The PID field in the TCB can temporarily be changed
-     (in fork).  But this must not affect this code here.  Since this
-     function would have to be called while the thread is executing
-     fork, it would have to happen in a signal handler.  But this is
-     no allowed, pthread_kill is not guaranteed to be async-safe.  */
-  int val;
-  val = INTERNAL_SYSCALL (tgkill, err, 3, THREAD_GETMEM (THREAD_SELF, pid),
-			  tid, signo);
+  pid_t pid = __getpid ();
 
+  int val = INTERNAL_SYSCALL_CALL (tgkill, err, pid, tid, signo);
   return (INTERNAL_SYSCALL_ERROR_P (val, err)
 	  ? INTERNAL_SYSCALL_ERRNO (val, err) : 0);
 }
diff --git a/sysdeps/unix/sysv/linux/pthread_sigqueue.c b/sysdeps/unix/sysv/linux/pthread_sigqueue.c
index 7694d54..e393e0b 100644
--- a/sysdeps/unix/sysv/linux/pthread_sigqueue.c
+++ b/sysdeps/unix/sysv/linux/pthread_sigqueue.c
@@ -49,27 +49,22 @@ pthread_sigqueue (pthread_t threadid, int signo, const union sigval value)
   if (signo == SIGCANCEL || signo == SIGTIMER || signo == SIGSETXID)
     return EINVAL;
 
+  pid_t pid = getpid ();
+
   /* Set up the siginfo_t structure.  */
   siginfo_t info;
   memset (&info, '\0', sizeof (siginfo_t));
   info.si_signo = signo;
   info.si_code = SI_QUEUE;
-  info.si_pid = THREAD_GETMEM (THREAD_SELF, pid);
+  info.si_pid = pid;
   info.si_uid = getuid ();
   info.si_value = value;
 
   /* We have a special syscall to do the work.  */
   INTERNAL_SYSCALL_DECL (err);
 
-  /* One comment: The PID field in the TCB can temporarily be changed
-     (in fork).  But this must not affect this code here.  Since this
-     function would have to be called while the thread is executing
-     fork, it would have to happen in a signal handler.  But this is
-     no allowed, pthread_sigqueue is not guaranteed to be async-safe.  */
-  int val = INTERNAL_SYSCALL (rt_tgsigqueueinfo, err, 4,
-			      THREAD_GETMEM (THREAD_SELF, pid),
-			      tid, signo, &info);
-
+  int val = INTERNAL_SYSCALL_CALL (rt_tgsigqueueinfo, err, pid, tid, signo,
+				   &info);
   return (INTERNAL_SYSCALL_ERROR_P (val, err)
 	  ? INTERNAL_SYSCALL_ERRNO (val, err) : 0);
 #else
diff --git a/sysdeps/unix/sysv/linux/raise.c b/sysdeps/unix/sysv/linux/raise.c
index 470033e..49bb7cb 100644
--- a/sysdeps/unix/sysv/linux/raise.c
+++ b/sysdeps/unix/sysv/linux/raise.c
@@ -26,13 +26,6 @@
 int
 raise (int sig)
 {
-  /* raise is an async-safe function so it could be called while the
-     fork/vfork function temporarily invalidated the PID field.  To avoid
-     relying on cached value we block all user-defined signal handler
-     (which might call fork/vfork) and issue the getpid and gettid
-     syscalls directly.  */
-
-
   /* rt_sigprocmask may fail if:
 
      1. sigsetsize != sizeof (sigset_t) (EINVAL)
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
index 2f8fa0b..b1de148 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/clone.S
@@ -54,13 +54,6 @@ error:
 PSEUDO_END (__clone)
 
 thread_start:
-	tml	%r3,256		/* CLONE_VM == 0x00000100 */
-	jne	1f
-	svc	SYS_ify(getpid)
-	ear	%r3,%a0
-	st	%r2,PID(%r3)
-	st	%r2,TID(%r3)
-1:
 	/* fn is in gpr 1, arg in gpr 0 */
 	lr      %r2,%r0         /* set first parameter to void *arg */
 	ahi     %r15,-96        /* make room on the stack for the save area */
diff --git a/sysdeps/unix/sysv/linux/s390/s390-32/vfork.S b/sysdeps/unix/sysv/linux/s390/s390-32/vfork.S
index b7588eb..cc60e13 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-32/vfork.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-32/vfork.S
@@ -28,21 +28,9 @@
    and the process ID of the new process to the old process.  */
 
 ENTRY (__libc_vfork)
-	ear	%r4,%a0
-	lhi	%r1,1
-	icm	%r3,15,PID(%r4)
-	sll	%r1,31
-	je	1f
-	lcr	%r1,%r3
-1:	st	%r1,PID(%r4)
-
 	/* Do vfork system call.  */
 	svc	SYS_ify (vfork)
 
-	ltr	%r2,%r2
-	je	1f
-	st	%r3,PID(%r4)
-1:
 	/* Check for error.  */
 	lhi	%r4,-4095
 	clr	%r2,%r4
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
index fb81692..29606ac 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/clone.S
@@ -55,15 +55,6 @@ error:
 PSEUDO_END (__clone)
 
 thread_start:
-	tmll	%r3,256		/* CLONE_VM == 0x00000100 */
-	jne	1f
-	svc	SYS_ify(getpid)
-	ear	%r3,%a0
-	sllg	%r3,%r3,32
-	ear	%r3,%a1
-	st	%r2,PID(%r3)
-	st	%r2,TID(%r3)
-1:
 	/* fn is in gpr 1, arg in gpr 0 */
 	lgr	%r2,%r0		/* set first parameter to void *arg */
 	aghi	%r15,-160	/* make room on the stack for the save area */
diff --git a/sysdeps/unix/sysv/linux/s390/s390-64/vfork.S b/sysdeps/unix/sysv/linux/s390/s390-64/vfork.S
index 0bd2161..b9a813f 100644
--- a/sysdeps/unix/sysv/linux/s390/s390-64/vfork.S
+++ b/sysdeps/unix/sysv/linux/s390/s390-64/vfork.S
@@ -28,22 +28,9 @@
    and the process ID of the new process to the old process.  */
 
 ENTRY (__libc_vfork)
-	ear	%r4,%a0
-	sllg	%r4,%r4,32
-	ear	%r4,%a1
-	icm	%r3,15,PID(%r4)
-	llilh	%r1,32768
-	je	1f
-	lcr	%r1,%r3
-1:	st	%r1,PID(%r4)
-
 	/* Do vfork system call.  */
 	svc	SYS_ify (vfork)
 
-	ltgr	%r2,%r2
-	je	1f
-	st	%r3,PID(%r4)
-1:
 	/* Check for error.  */
 	lghi	%r4,-4095
 	clgr	%r2,%r4
diff --git a/sysdeps/unix/sysv/linux/sh/clone.S b/sysdeps/unix/sysv/linux/sh/clone.S
index 4cd7df1..ce7cddc 100644
--- a/sysdeps/unix/sysv/linux/sh/clone.S
+++ b/sysdeps/unix/sysv/linux/sh/clone.S
@@ -66,23 +66,7 @@ ENTRY(__clone)
 2:
 	/* terminate the stack frame */
 	mov	#0, r14
-	mov	r4, r0
-	shlr8	r0
-	tst	#1, r0			// CLONE_VM = (1 << 8)
-	bf/s	4f
-	 mov	r4, r0
-	/* new pid */
-	mov	#+SYS_ify(getpid), r3
-	trapa	#0x15
-3:
-	stc	gbr, r1
-	mov.w	.Lpidoff, r2
-	add	r1, r2
-	mov.l	r0, @r2
-	mov.w	.Ltidoff, r2
-	add	r1, r2
-	mov.l	r0, @r2
-4:
+
 	/* thread starts */
 	mov.l	@r15, r1
 	jsr	@r1
@@ -113,10 +97,6 @@ ENTRY(__clone)
 	.long	_GLOBAL_OFFSET_TABLE_
 .L3:
 	.long	PLTJMP(C_SYMBOL_NAME(_exit))
-.Lpidoff:
-	.word	PID - TLS_PRE_TCB_SIZE
-.Ltidoff:
-	.word	TID - TLS_PRE_TCB_SIZE
 PSEUDO_END (__clone)
 
 libc_hidden_def (__clone)
diff --git a/sysdeps/unix/sysv/linux/sh/vfork.S b/sysdeps/unix/sysv/linux/sh/vfork.S
index 6895bc5..df559cb 100644
--- a/sysdeps/unix/sysv/linux/sh/vfork.S
+++ b/sysdeps/unix/sysv/linux/sh/vfork.S
@@ -26,30 +26,11 @@
    and the process ID of the new process to the old process.  */
 
 ENTRY (__libc_vfork)
-	/* Save the PID value.  */
-	stc	gbr, r2
-	mov.w	.L2, r0
-	mov.l	@(r0,r2), r4
-	neg	r4, r1
-	tst	r1, r1
-	bf	1f
-	mov	#1, r1
-	rotr	r1
-1:
-	mov.l	r1, @(r0,r2)
 
 	mov.w	.L1, r3
 	trapa	#0x10
 	mov     r0, r1
 
-	/* Restore the old PID value in the parent.  */
-	tst	r0, r0
-	bt.s	2f
-	 stc	gbr, r2
-	mov.w	.L2, r0
-	mov.l	r4, @(r0,r2)
-	mov	r1, r0
-2:
 	mov	#-12, r2
 	shad	r2, r1
 	not	r1, r1			// r1=0 means r0 = -1 to -4095
@@ -61,8 +42,6 @@ ENTRY (__libc_vfork)
 	 nop
 .L1:
 	.word	__NR_vfork
-.L2:
-	.word	PID - TLS_PRE_TCB_SIZE
 	.align	2
 PSEUDO_END (__libc_vfork)
 
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
index d6c92f6..0456a0d 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/clone.S
@@ -79,13 +79,6 @@ END(__clone)
 
 	.type	__thread_start,@function
 __thread_start:
-	andcc	%g4, CLONE_VM, %g0
-	bne	1f
-	set	__NR_getpid,%g1
-	ta	0x10
-	st	%o0,[%g7 + PID]
-	st	%o0,[%g7 + TID]
-1:
 	mov	%g0, %fp	/* terminate backtrace */
 	call	%g2
 	 mov	%g3,%o0
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S b/sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S
index 0d0a3b5..6d98503 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/vfork.S
@@ -22,24 +22,14 @@
 	.text
 	.globl		__syscall_error
 ENTRY(__libc_vfork)
-	ld	[%g7 + PID], %o5
-	cmp	%o5, 0
-	bne	1f
-	 sub	%g0, %o5, %o4
-	sethi	%hi(0x80000000), %o4
-1:	st	%o4, [%g7 + PID]
-
 	LOADSYSCALL(vfork)
 	ta	0x10
 	bcc	2f
 	 mov	%o7, %g1
-	st	%o5, [%g7 + PID]
 	call	__syscall_error
 	 mov	%g1, %o7
 2:	sub	%o1, 1, %o1
 	andcc	%o0, %o1, %o0
-	bne,a	1f
-	 st	%o5, [%g7 + PID]
 1:	retl
 	 nop
 END(__libc_vfork)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
index b0f6266..6ffead8 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/clone.S
@@ -76,13 +76,6 @@ END(__clone)
 
 	.type __thread_start,@function
 __thread_start:
-	andcc	%g4, CLONE_VM, %g0
-	bne,pt	%icc, 1f
-	set	__NR_getpid,%g1
-	ta	0x6d
-	st	%o0,[%g7 + PID]
-	st	%o0,[%g7 + TID]
-1:
 	mov	%g0, %fp	/* terminate backtrace */
 	call	%g2
 	 mov	%g3,%o0
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S b/sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S
index 0818eba..298dd19 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/vfork.S
@@ -22,24 +22,14 @@
 	.text
 	.globl	__syscall_error
 ENTRY(__libc_vfork)
-	ld	[%g7 + PID], %o5
-	sethi	%hi(0x80000000), %o3
-	cmp	%o5, 0
-	sub	%g0, %o5, %o4
-	move	%icc, %o3, %o4
-	st	%o4, [%g7 + PID]
-
 	LOADSYSCALL(vfork)
 	ta	0x6d
 	bcc,pt	%xcc, 2f
 	 mov	%o7, %g1
-	st	%o5, [%g7 + PID]
 	call	__syscall_error
 	 mov	%g1, %o7
 2:	sub	%o1, 1, %o1
 	andcc	%o0, %o1, %o0
-	bne,a,pt %icc, 1f
-	 st	%o5, [%g7 + PID]
 1:	retl
 	 nop
 END(__libc_vfork)
diff --git a/sysdeps/unix/sysv/linux/syscalls.list b/sysdeps/unix/sysv/linux/syscalls.list
index 7ae2541..248641b 100644
--- a/sysdeps/unix/sysv/linux/syscalls.list
+++ b/sysdeps/unix/sysv/linux/syscalls.list
@@ -18,6 +18,7 @@ execve		-	execve		i:spp	__execve	execve
 fdatasync	-	fdatasync	Ci:i	fdatasync
 flock		-	flock		i:ii	__flock		flock
 get_kernel_syms	EXTRA	get_kernel_syms	i:p	__compat_get_kernel_syms	get_kernel_syms@GLIBC_2.0:GLIBC_2.23
+getpid          -       getpid          Ei:     __getpid        getpid
 getegid		-	getegid		Ei:	__getegid	getegid
 geteuid		-	geteuid		Ei:	__geteuid	geteuid
 getpgid		-	getpgid		i:i	__getpgid	getpgid
diff --git a/sysdeps/unix/sysv/linux/tile/clone.S b/sysdeps/unix/sysv/linux/tile/clone.S
index d1d3646..3f9e3d5 100644
--- a/sysdeps/unix/sysv/linux/tile/clone.S
+++ b/sysdeps/unix/sysv/linux/tile/clone.S
@@ -163,22 +163,6 @@ ENTRY (__clone)
 .Lthread_start:
 	cfi_def_cfa_offset (FRAME_SIZE)
 	cfi_undefined (lr)
-	/* Check and see if we need to reset the PID, which we do if
-	   CLONE_VM isn't set, i.e. it's a fork-like clone with a new
-	   address space.  In that case we update the cached values
-	   from the true system pid (retrieved via __NR_getpid syscall).  */
-	moveli r0, CLONE_VM
-	and r0, r30, r0
-	BNEZ r0, .Lno_reset_pid   /* CLONE_VM is set */
-	moveli TREG_SYSCALL_NR_NAME, __NR_getpid
-	swint1
-	ADDLI_PTR r2, tp, PID_OFFSET
-	{
-	 ST4 r2, r0
-	 ADDLI_PTR r2, tp, TID_OFFSET
-	}
-	ST4 r2, r0
-.Lno_reset_pid:
 	{
 	 /* Invoke user function with specified argument. */
 	 move r0, r31
diff --git a/sysdeps/unix/sysv/linux/tile/vfork.S b/sysdeps/unix/sysv/linux/tile/vfork.S
index d8c5ce3..2272777 100644
--- a/sysdeps/unix/sysv/linux/tile/vfork.S
+++ b/sysdeps/unix/sysv/linux/tile/vfork.S
@@ -30,18 +30,6 @@
 	.text
 ENTRY (__vfork)
 	{
-	 addli r11, tp, PID_OFFSET	/* Point at PID. */
-	 movei r13, 1
-	}
-	{
-	 LD4U r12, r11			/* Load the saved PID.  */
-	 shli r13, r13, 31		/* Build 0x80000000. */
-	}
-	sub r12, zero, r12		/* Negate it.  */
-	CMOVEQZ r12, r12, r13		/* Replace zero pids.  */
-	ST4 r11, r12			/* Store the temporary PID.  */
-
-	{
 	 moveli r0, CLONE_VFORK | CLONE_VM | SIGCHLD
 	 move r1, zero
 	}
@@ -52,22 +40,6 @@ ENTRY (__vfork)
 	moveli TREG_SYSCALL_NR_NAME, __NR_clone
 	swint1
 
-	BEQZ r0, 1f			/* If we are the parent... */
-	{
-	 addli r11, tp, PID_OFFSET	/* Point at PID. */
-	 movei r13, 1
-	}
-	{
-	 LD4U r12, r11			/* Load the saved PID.  */
-	 shli r13, r13, 31		/* Build 0x80000000. */
-	}
-	{
-	 CMPEQ r13, r12, r12		/* Test for that value. */
-	 sub r12, zero, r12		/* Re-negate it.  */
-	}
-	CMOVNEZ r12, r13, zero		/* Replace zero pids.  */
-	ST4 r11, r12			/* Restore the PID.  */
-1:
 	BNEZ r1, 0f
 	jrp lr
 PSEUDO_END (__vfork)
diff --git a/sysdeps/unix/sysv/linux/tst-clone2.c b/sysdeps/unix/sysv/linux/tst-clone2.c
index 68a7e6d..0da9e54 100644
--- a/sysdeps/unix/sysv/linux/tst-clone2.c
+++ b/sysdeps/unix/sysv/linux/tst-clone2.c
@@ -28,8 +28,14 @@
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/wait.h>
+#include <sys/syscall.h>
 
-#include <tls.h> /* for THREAD_* macros.  */
+#include <stackinfo.h>  /* For _STACK_GROWS_{UP,DOWN}.  */
+
+static int do_test (void);
+
+#define TEST_FUNCTION do_test ()
+#include <test-skeleton.c>
 
 static int sig;
 static int pipefd[2];
@@ -39,39 +45,35 @@ f (void *a)
 {
   close (pipefd[0]);
 
-  pid_t pid = THREAD_GETMEM (THREAD_SELF, pid);
-  pid_t tid = THREAD_GETMEM (THREAD_SELF, tid);
+  pid_t ppid = getppid ();
+  pid_t pid = getpid ();
+  pid_t tid = syscall (__NR_gettid);
 
-  while (write (pipefd[1], &pid, sizeof pid) < 0)
-    continue;
-  while (write (pipefd[1], &tid, sizeof tid) < 0)
-    continue;
+  if (write (pipefd[1], &ppid, sizeof ppid) != sizeof (ppid))
+    FAIL_EXIT1 ("write ppid failed\n");
+  if (write (pipefd[1], &pid, sizeof pid) != sizeof (pid))
+    FAIL_EXIT1 ("write pid failed\n");
+  if (write (pipefd[1], &tid, sizeof tid) != sizeof (tid))
+    FAIL_EXIT1 ("write tid failed\n");
 
   return 0;
 }
 
 
 static int
-clone_test (int clone_flags)
+do_test (void)
 {
   sig = SIGRTMIN;
   sigset_t ss;
   sigemptyset (&ss);
   sigaddset (&ss, sig);
   if (sigprocmask (SIG_BLOCK, &ss, NULL) != 0)
-    {
-      printf ("sigprocmask failed: %m\n");
-      return 1;
-    }
+    FAIL_EXIT1 ("sigprocmask failed: %m");
 
   if (pipe2 (pipefd, O_CLOEXEC))
-    {
-      printf ("sigprocmask failed: %m\n");
-      return 1;
-    }
-
-  pid_t ppid = getpid ();
+    FAIL_EXIT1 ("pipe failed: %m");
 
+  int clone_flags = 0;
 #ifdef __ia64__
   extern int __clone2 (int (*__fn) (void *__arg), void *__child_stack_base,
 		       size_t __child_stack_size, int __flags,
@@ -88,61 +90,47 @@ clone_test (int clone_flags)
 #error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP"
 #endif
 #endif
+
   close (pipefd[1]);
 
   if (p == -1)
+    FAIL_EXIT1("clone failed: %m");
+
+  pid_t ppid, pid, tid;
+  if (read (pipefd[0], &ppid, sizeof pid) != sizeof pid)
     {
-      printf ("clone failed: %m\n");
-      return 1;
+      kill (p, SIGKILL);
+      FAIL_EXIT1 ("read ppid failed: %m");
     }
-
-  pid_t pid, tid;
   if (read (pipefd[0], &pid, sizeof pid) != sizeof pid)
     {
-      printf ("read pid failed: %m\n");
       kill (p, SIGKILL);
-      return 1;
+      FAIL_EXIT1 ("read pid failed: %m");
     }
   if (read (pipefd[0], &tid, sizeof tid) != sizeof tid)
     {
-      printf ("read pid failed: %m\n");
       kill (p, SIGKILL);
-      return 1;
+      FAIL_EXIT1 ("read tid failed: %m");
     }
 
   close (pipefd[0]);
 
   int ret = 0;
 
-  /* For CLONE_VM glibc clone implementation does not change the pthread
-     pid/tid field.  */
-  if ((clone_flags & CLONE_VM) == CLONE_VM)
-    {
-      if ((ppid != pid) || (ppid != tid))
-	{
-	  printf ("parent pid (%i) != received pid/tid (%i/%i)\n",
-		  (int)ppid, (int)pid, (int)tid);
-	  ret = 1;
-	}
-    }
-  /* For any other flag clone updates the new pthread pid and tid with
-     the clone return value.  */
-  else
-    {
-      if ((p != pid) || (p != tid))
-	{
-	  printf ("child pid (%i) != received pid/tid (%i/%i)\n",
-		  (int)p, (int)pid, (int)tid);
-	  ret = 1;
-	}
-    }
+  pid_t own_pid = getpid ();
+  pid_t own_tid = syscall (__NR_gettid);
+
+  /* Some sanity checks for clone syscall: returned ppid should be current
+     pid and both returned tid/pid should be different from current one.  */
+  if ((ppid != own_pid) || (pid == own_pid) || (tid == own_tid))
+    FAIL_RET ("ppid=%i pid=%i tid=%i | own_pid=%i own_tid=%i",
+	      (int)ppid, (int)pid, (int)tid, (int)own_pid, (int)own_tid);
 
   int e;
   if (waitpid (p, &e, __WCLONE) != p)
     {
-      puts ("waitpid failed");
       kill (p, SIGKILL);
-      return 1;
+      FAIL_EXIT1 ("waitpid failed");
     }
   if (!WIFEXITED (e))
     {
@@ -150,29 +138,10 @@ clone_test (int clone_flags)
 	printf ("died from signal %s\n", strsignal (WTERMSIG (e)));
       else
 	puts ("did not terminate correctly");
-      return 1;
+      exit (EXIT_FAILURE);
     }
   if (WEXITSTATUS (e) != 0)
-    {
-      printf ("exit code %d\n", WEXITSTATUS (e));
-      return 1;
-    }
+    FAIL_EXIT1 ("exit code %d", WEXITSTATUS (e));
 
   return ret;
 }
-
-int
-do_test (void)
-{
-  /* First, check that the clone implementation, without any flag, updates
-     the struct pthread to contain the new PID and TID.  */
-  int ret = clone_test (0);
-  /* Second, check that with CLONE_VM the struct pthread PID and TID fields
-     remain unmodified after the clone.  Any modifications would cause problem
-     for the parent as described in bug 19957.  */
-  ret += clone_test (CLONE_VM);
-  return ret;
-}
-
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
diff --git a/sysdeps/unix/sysv/linux/x86_64/clone.S b/sysdeps/unix/sysv/linux/x86_64/clone.S
index 66f4b11..5629aed 100644
--- a/sysdeps/unix/sysv/linux/x86_64/clone.S
+++ b/sysdeps/unix/sysv/linux/x86_64/clone.S
@@ -91,14 +91,6 @@ L(thread_start):
 	   the outermost frame obviously.  */
 	xorl	%ebp, %ebp
 
-	andq	$CLONE_VM, %rdi
-	jne	1f
-	movl	$SYS_ify(getpid), %eax
-	syscall
-	movl	%eax, %fs:PID
-	movl	%eax, %fs:TID
-1:
-
 	/* Set up arguments for the function call.  */
 	popq	%rax		/* Function to call.  */
 	popq	%rdi		/* Argument.  */
diff --git a/sysdeps/unix/sysv/linux/x86_64/vfork.S b/sysdeps/unix/sysv/linux/x86_64/vfork.S
index 8332ade..cdd2dea 100644
--- a/sysdeps/unix/sysv/linux/x86_64/vfork.S
+++ b/sysdeps/unix/sysv/linux/x86_64/vfork.S
@@ -34,16 +34,6 @@ ENTRY (__vfork)
 	cfi_adjust_cfa_offset(-8)
 	cfi_register(%rip, %rdi)
 
-	/* Save the TCB-cached PID away in %esi, and then negate the TCB
-           field.  But if it's zero, set it to 0x80000000 instead.  See
-           raise.c for the logic that relies on this value.  */
-	movl	%fs:PID, %esi
-	movl	$0x80000000, %ecx
-	movl	%esi, %edx
-	negl	%edx
-	cmove	%ecx, %edx
-	movl	%edx, %fs:PID
-
 	/* Stuff the syscall number in RAX and enter into the kernel.  */
 	movl	$SYS_ify (vfork), %eax
 	syscall
@@ -52,14 +42,6 @@ ENTRY (__vfork)
 	pushq	%rdi
 	cfi_adjust_cfa_offset(8)
 
-	/* Restore the original value of the TCB cache of the PID, if we're
-	   the parent.  But in the child (syscall return value equals zero),
-	   leave things as they are.  */
-	testq	%rax, %rax
-	je	1f
-	movl	%esi, %fs:PID
-1:
-
 	cmpl	$-4095, %eax
 	jae SYSCALL_ERROR_LABEL		/* Branch forward if it failed.  */
 
diff --git a/sysdeps/x86_64/nptl/tcb-offsets.sym b/sysdeps/x86_64/nptl/tcb-offsets.sym
index aeb7526..8a25c48 100644
--- a/sysdeps/x86_64/nptl/tcb-offsets.sym
+++ b/sysdeps/x86_64/nptl/tcb-offsets.sym
@@ -4,7 +4,6 @@
 
 RESULT			offsetof (struct pthread, result)
 TID			offsetof (struct pthread, tid)
-PID			offsetof (struct pthread, pid)
 CANCELHANDLING		offsetof (struct pthread, cancelhandling)
 CLEANUP_JMP_BUF		offsetof (struct pthread, cleanup_jmp_buf)
 CLEANUP			offsetof (struct pthread, cleanup)

http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=80718499347b1481713951528ced70693ad0e351

commit 80718499347b1481713951528ced70693ad0e351
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Jun 30 16:34:18 2016 -0300

    Add INTERNAL_SYSCALL_CALL
    
    This patch adds two new macros for internal and inline syscall to use
    within GLIBC: INTERNAL_SYSCALL_CALL and INLINE_SYSCALL_CALL.  They are
    similar to the old INTERNAL_SYSCALL and INLINE_SYSCALL with the difference
    the new macros accept a variable argument call and do not require to pass
    the expected argument size.
    
    The advantage is it is possible to use variable argument macros like
    SYSCALL_LL{64} without the need to also handle the argument size.  So
    for an ABI where SYSCALL_LL might split the argument in high and low
    parts, instead of:
    
      INTERNAL_SYSCALL_DECL (err);
     #if ...
      INTERNAL_SYSCALL (syscall, err, 2, SYSCALL_LL (len));
     #else
      INTERNAL_SYSCALL (syscall, err, 1, SYSCALL_LL (len));
     #endif
    
    It will be just:
    
      INTERNAL_SYSCALL_CALL (syscall, err, SYSCALL_LL (len));
    
    The INLINE_SYSCALL_CALL follows the same semanthic regarding the argument
    and is similar to INLINE_SYSCALL regarding setting errno.
    
    Checked with a build for x86_64, i386, aach64, armhf, powerpc64le, powerpc32,
    and mips32.  No code generation changed.
    
    	* sysdeps/unix/sysdep.h (__INTERNAL_SYSCALL0): New macro.
    	(__INTERNAL_SYSCALL1): Likewise.
    	(__INTERNAL_SYSCALL2): Likewise.
    	(__INTERNAL_SYSCALL3): Likewise.
    	(__INTERNAL_SYSCALL4): Likewise.
    	(__INTERNAL_SYSCALL5): Likewise.
    	(__INTERNAL_SYSCALL6): Likewise.
    	(__INTERNAL_SYSCALL7): Likewise.
    	(__INTERNAL_SYSCALL_NARGS_X): Likewise.
    	(__INTERNAL_SYSCALL_NARGS): Likewise.
    	(__INTERNAL_SYSCALL_DISP): Likewise.
    	(INTERNAL_SYSCALL_CALL): Likewise.
    	(__SYSCALL0): Rename to __INLINE_SYSCALL0.
    	(__SYSCALL1): Rename to __INLINE_SYSCALL1.
    	(__SYSCALL2): Rename to __INLINE_SYSCALL2.
    	(__SYSCALL3): Rename to __INLINE_SYSCALL3.
    	(__SYSCALL4): Rename to __INLINE_SYSCALL4.
    	(__SYSCALL5): Rename to __INLINE_SYSCALL5.
    	(__SYSCALL6): Rename to __INLINE_SYSCALL6.
    	(__SYSCALL7): Rename to __INLINE_SYSCALL7.
    	(__SYSCALL_NARGS_X): Rename to __INLINE_SYSCALL_NARGS_X.
    	(__SYSCALL_NARGS): Rename to __INLINE_SYSCALL_NARGS.
    	(__SYSCALL_DISP): Rename to __INLINE_SYSCALL_DISP.
    	(__SYSCALL_CALL): Rename to INLINE_SYSCALL_CALL.
    	(SYSCALL_CANCEL): Replace __SYSCALL_CALL with INLINE_SYSCALL_CALL.
    
    (cherry picked from commit e33a23fbe8c2dba04fe05678c584d3efcb6c9951)

diff --git a/ChangeLog b/ChangeLog
index 8734292..f0c8e7d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,31 @@
+2016-09-26  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	* sysdeps/unix/sysdep.h (__INTERNAL_SYSCALL0): New macro.
+	(__INTERNAL_SYSCALL1): Likewise.
+	(__INTERNAL_SYSCALL2): Likewise.
+	(__INTERNAL_SYSCALL3): Likewise.
+	(__INTERNAL_SYSCALL4): Likewise.
+	(__INTERNAL_SYSCALL5): Likewise.
+	(__INTERNAL_SYSCALL6): Likewise.
+	(__INTERNAL_SYSCALL7): Likewise.
+	(__INTERNAL_SYSCALL_NARGS_X): Likewise.
+	(__INTERNAL_SYSCALL_NARGS): Likewise.
+	(__INTERNAL_SYSCALL_DISP): Likewise.
+	(INTERNAL_SYSCALL_CALL): Likewise.
+	(__SYSCALL0): Rename to __INLINE_SYSCALL0.
+	(__SYSCALL1): Rename to __INLINE_SYSCALL1.
+	(__SYSCALL2): Rename to __INLINE_SYSCALL2.
+	(__SYSCALL3): Rename to __INLINE_SYSCALL3.
+	(__SYSCALL4): Rename to __INLINE_SYSCALL4.
+	(__SYSCALL5): Rename to __INLINE_SYSCALL5.
+	(__SYSCALL6): Rename to __INLINE_SYSCALL6.
+	(__SYSCALL7): Rename to __INLINE_SYSCALL7.
+	(__SYSCALL_NARGS_X): Rename to __INLINE_SYSCALL_NARGS_X.
+	(__SYSCALL_NARGS): Rename to __INLINE_SYSCALL_NARGS.
+	(__SYSCALL_DISP): Rename to __INLINE_SYSCALL_DISP.
+	(__SYSCALL_CALL): Rename to INLINE_SYSCALL_CALL.
+	(SYSCALL_CANCEL): Replace __SYSCALL_CALL with INLINE_SYSCALL_CALL.
+
 2017-04-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ #21396]
diff --git a/sysdeps/unix/sysdep.h b/sysdeps/unix/sysdep.h
index 94a2ce0..38c2432 100644
--- a/sysdeps/unix/sysdep.h
+++ b/sysdeps/unix/sysdep.h
@@ -24,42 +24,79 @@
 #define	SYSCALL__(name, args)	PSEUDO (__##name, name, args)
 #define	SYSCALL(name, args)	PSEUDO (name, name, args)
 
-#define __SYSCALL0(name) \
+#define __SYSCALL_CONCAT_X(a,b)     a##b
+#define __SYSCALL_CONCAT(a,b)       __SYSCALL_CONCAT_X (a, b)
+
+
+#define __INTERNAL_SYSCALL0(name, err) \
+  INTERNAL_SYSCALL (name, err, 0)
+#define __INTERNAL_SYSCALL1(name, err, a1) \
+  INTERNAL_SYSCALL (name, err, 1, a1)
+#define __INTERNAL_SYSCALL2(name, err, a1, a2) \
+  INTERNAL_SYSCALL (name, err, 2, a1, a2)
+#define __INTERNAL_SYSCALL3(name, err, a1, a2, a3) \
+  INTERNAL_SYSCALL (name, err, 3, a1, a2, a3)
+#define __INTERNAL_SYSCALL4(name, err, a1, a2, a3, a4) \
+  INTERNAL_SYSCALL (name, err, 4, a1, a2, a3, a4)
+#define __INTERNAL_SYSCALL5(name, err, a1, a2, a3, a4, a5) \
+  INTERNAL_SYSCALL (name, err, 5, a1, a2, a3, a4, a5)
+#define __INTERNAL_SYSCALL6(name, err, a1, a2, a3, a4, a5, a6) \
+  INTERNAL_SYSCALL (name, err, 6, a1, a2, a3, a4, a5, a6)
+#define __INTERNAL_SYSCALL7(name, err, a1, a2, a3, a4, a5, a6, a7) \
+  INTERNAL_SYSCALL (name, err, 7, a1, a2, a3, a4, a5, a6, a7)
+
+#define __INTERNAL_SYSCALL_NARGS_X(a,b,c,d,e,f,g,h,n,o,...) o
+#define __INTERNAL_SYSCALL_NARGS(...) \
+  __INTERNAL_SYSCALL_NARGS_X (__VA_ARGS__,7,6,5,4,3,2,1,0,)
+#define __INTERNAL_SYSCALL_DISP(b,...) \
+  __SYSCALL_CONCAT (b,__INTERNAL_SYSCALL_NARGS(__VA_ARGS__))(__VA_ARGS__)
+
+/* Issue a syscall defined by syscall number plus any other argument required.
+   It is similar to INTERNAL_SYSCALL macro, but without the need to pass the
+   expected argument number as second parameter.  */
+#define INTERNAL_SYSCALL_CALL(...) \
+  __INTERNAL_SYSCALL_DISP (__INTERNAL_SYSCALL, __VA_ARGS__)
+
+#define __INLINE_SYSCALL0(name) \
   INLINE_SYSCALL (name, 0)
-#define __SYSCALL1(name, a1) \
+#define __INLINE_SYSCALL1(name, a1) \
   INLINE_SYSCALL (name, 1, a1)
-#define __SYSCALL2(name, a1, a2) \
+#define __INLINE_SYSCALL2(name, a1, a2) \
   INLINE_SYSCALL (name, 2, a1, a2)
-#define __SYSCALL3(name, a1, a2, a3) \
+#define __INLINE_SYSCALL3(name, a1, a2, a3) \
   INLINE_SYSCALL (name, 3, a1, a2, a3)
-#define __SYSCALL4(name, a1, a2, a3, a4) \
+#define __INLINE_SYSCALL4(name, a1, a2, a3, a4) \
   INLINE_SYSCALL (name, 4, a1, a2, a3, a4)
-#define __SYSCALL5(name, a1, a2, a3, a4, a5) \
+#define __INLINE_SYSCALL5(name, a1, a2, a3, a4, a5) \
   INLINE_SYSCALL (name, 5, a1, a2, a3, a4, a5)
-#define __SYSCALL6(name, a1, a2, a3, a4, a5, a6) \
+#define __INLINE_SYSCALL6(name, a1, a2, a3, a4, a5, a6) \
   INLINE_SYSCALL (name, 6, a1, a2, a3, a4, a5, a6)
-#define __SYSCALL7(name, a1, a2, a3, a4, a5, a6, a7) \
+#define __INLINE_SYSCALL7(name, a1, a2, a3, a4, a5, a6, a7) \
   INLINE_SYSCALL (name, 7, a1, a2, a3, a4, a5, a6, a7)
 
-#define __SYSCALL_NARGS_X(a,b,c,d,e,f,g,h,n,...) n
-#define __SYSCALL_NARGS(...) \
-  __SYSCALL_NARGS_X (__VA_ARGS__,7,6,5,4,3,2,1,0,)
-#define __SYSCALL_CONCAT_X(a,b)     a##b
-#define __SYSCALL_CONCAT(a,b)       __SYSCALL_CONCAT_X (a, b)
-#define __SYSCALL_DISP(b,...) \
-  __SYSCALL_CONCAT (b,__SYSCALL_NARGS(__VA_ARGS__))(__VA_ARGS__)
+#define __INLINE_SYSCALL_NARGS_X(a,b,c,d,e,f,g,h,n,...) n
+#define __INLINE_SYSCALL_NARGS(...) \
+  __INLINE_SYSCALL_NARGS_X (__VA_ARGS__,7,6,5,4,3,2,1,0,)
+#define __INLINE_SYSCALL_DISP(b,...) \
+  __SYSCALL_CONCAT (b,__INLINE_SYSCALL_NARGS(__VA_ARGS__))(__VA_ARGS__)
 
-#define __SYSCALL_CALL(...) __SYSCALL_DISP (__SYSCALL, __VA_ARGS__)
+/* Issue a syscall defined by syscall number plus any other argument
+   required.  Any error will be handled using arch defined macros and errno
+   will be set accordingly.
+   It is similar to INLINE_SYSCALL macro, but without the need to pass the
+   expected argument number as second parameter.  */
+#define INLINE_SYSCALL_CALL(...) \
+  __INLINE_SYSCALL_DISP (__INLINE_SYSCALL, __VA_ARGS__)
 
 #define SYSCALL_CANCEL(...) \
   ({									     \
     long int sc_ret;							     \
     if (SINGLE_THREAD_P) 						     \
-      sc_ret = __SYSCALL_CALL (__VA_ARGS__);   				     \
+      sc_ret = INLINE_SYSCALL_CALL (__VA_ARGS__); 			     \
     else								     \
       {									     \
 	int sc_cancel_oldtype = LIBC_CANCEL_ASYNC ();			     \
-	sc_ret = __SYSCALL_CALL (__VA_ARGS__);				     \
+	sc_ret = INLINE_SYSCALL_CALL (__VA_ARGS__);			     \
         LIBC_CANCEL_RESET (sc_cancel_oldtype);				     \
       }									     \
     sc_ret;								     \

http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=4c5785aa129a5d195fc1cd5c7fcd6f62c2b0ff0c

commit 4c5785aa129a5d195fc1cd5c7fcd6f62c2b0ff0c
Author: Arjun Shankar <arjun.is@lostca.se>
Date:   Wed Jun 7 11:46:24 2017 +0200

    Synchronize support/ infrastructure with master
    
    This commit updates the support/ subdirectory to
    commit 2714c5f3c95f90977167c1d21326d907fb76b419
    on the master branch and modifies Makeconfig,
    Rules, and extra-lib.mk accordingly.

diff --git a/Makeconfig b/Makeconfig
index 03fd89c..ee379f5 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -394,6 +394,9 @@ ifndef after-link
 after-link =
 endif
 
+# Additional libraries to link into every test.
+link-extra-libs-tests = $(libsupport)
+
 # Command for linking PIE programs with the C library.
 ifndef +link-pie
 +link-pie-before-libc = $(CC) -pie -Wl,-O1 -nostdlib -nostartfiles -o $@ \
@@ -503,7 +506,7 @@ link-libc = $(link-libc-rpath-link) $(link-libc-before-gnulib) $(gnulib)
 link-libc-tests = $(link-libc-tests-rpath-link) \
 		  $(link-libc-before-gnulib) $(gnulib-tests)
 # This is how to find at build-time things that will be installed there.
-rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec
+rpath-dirs = math elf dlfcn nss nis rt resolv crypt mathvec support
 rpath-link = \
 $(common-objdir):$(subst $(empty) ,:,$(patsubst ../$(subdir),.,$(rpath-dirs:%=$(common-objpfx)%)))
 else
@@ -850,7 +853,7 @@ libio-include = -I$(..)libio
 # List of non-library modules that we build.
 built-modules = iconvprogs iconvdata ldconfig lddlibc4 libmemusage \
 		libSegFault libpcprofile librpcsvc locale-programs \
-		memusagestat nonlib nscd extramodules libnldbl
+		memusagestat nonlib nscd extramodules libnldbl libsupport
 
 in-module = $(subst -,_,$(firstword $(libof-$(basename $(@F))) \
 				    $(libof-$(<F)) \
@@ -1089,6 +1092,12 @@ libm = $(common-objpfx)math/libm.a
 libmvec = $(common-objpfx)mathvec/libmvec.a
 endif
 
+ifeq ($(build-shared),yes)
+libsupport = $(common-objpfx)support/libsupport_nonshared.a
+else
+libsupport = $(common-objpfx)support/libsupport.a
+endif
+
 # These are the subdirectories containing the library source.  The order
 # is more or less arbitrary.  The sorting step will take care of the
 # dependencies.
@@ -1096,7 +1105,7 @@ all-subdirs = csu assert ctype locale intl catgets math setjmp signal	    \
 	      stdlib stdio-common libio malloc string wcsmbs time dirent    \
 	      grp pwd posix io termios resource misc socket sysvipc gmon    \
 	      gnulib iconv iconvdata wctype manual shadow gshadow po argp   \
-	      crypt localedata timezone rt conform debug mathvec	    \
+	      crypt localedata timezone rt conform debug mathvec support    \
 	      $(add-on-subdirs) dlfcn elf
 
 ifndef avoid-generated
diff --git a/Rules b/Rules
index 8306d36..a981965 100644
--- a/Rules
+++ b/Rules
@@ -149,6 +149,7 @@ endif
 
 ifneq "$(strip $(binaries-shared-tests))" ""
 $(addprefix $(objpfx),$(binaries-shared-tests)): %: %.o \
+  $(link-extra-libs-tests) \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link-tests)
@@ -156,6 +157,7 @@ endif
 
 ifneq "$(strip $(binaries-pie-tests))" ""
 $(addprefix $(objpfx),$(binaries-pie-tests)): %: %.o \
+  $(link-extra-libs-tests) \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link-pie-tests)
@@ -177,6 +179,7 @@ endif
 
 ifneq "$(strip $(binaries-static-tests))" ""
 $(addprefix $(objpfx),$(binaries-static-tests)): %: %.o \
+  $(link-extra-libs-tests) \
   $(sort $(filter $(common-objpfx)lib%,$(link-libc-static-tests))) \
   $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
 	$(+link-static-tests)
diff --git a/extra-lib.mk b/extra-lib.mk
index b10748d..2552049 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -5,6 +5,9 @@
 # The variable $($(lib)-routines) defines the list of modules
 # to be included in that library.  A sysdep Makefile can add to
 # $(lib)-sysdep_routines to include additional modules.
+#
+# Libraries listed in $(extra-libs-noinstall) are built, but not
+# installed.
 
 lib := $(firstword $(extra-libs-left))
 extra-libs-left := $(filter-out $(lib),$(extra-libs-left))
@@ -28,7 +31,9 @@ extra-objs := $(extra-objs)
 all-$(lib)-routines := $($(lib)-routines) $($(lib)-sysdep_routines)
 
 # Add each flavor of library to the lists of things to build and install.
+ifeq (,$(filter $(lib), $(extra-libs-noinstall)))
 install-lib += $(foreach o,$(object-suffixes-$(lib)),$(lib:lib%=$(libtype$o)))
+endif
 extra-objs += $(foreach o,$(filter-out .os .oS,$(object-suffixes-$(lib))),\
 			$(patsubst %,%$o,$(filter-out \
 					   $($(lib)-shared-only-routines),\
diff --git a/scripts/backport-support.sh b/scripts/backport-support.sh
new file mode 100644
index 0000000..2ece7ce
--- /dev/null
+++ b/scripts/backport-support.sh
@@ -0,0 +1,110 @@
+#!/bin/bash
+# Create a patch which backports the support/ subdirectory.
+# Copyright (C) 2017 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+# This script does not backport the Makefile tweaks outside the
+# support/ directory (which need to be backported separately), or the
+# changes to test-skeleton.c (which should not be backported).
+
+set -e
+
+export LC_ALL=C
+export GIT_CONFIG=/dev/null
+export GTT_CONFIG_NOSYSTEM=0
+export GIT_PAGER=
+
+usage () {
+    cat >&2 <<EOF
+usage: $0 {patch|commit}
+EOF
+    exit 1
+}
+
+if test $# -ne 1 ; then
+    usage
+fi
+
+command="$1"
+
+case "$command" in
+    patch|commit)
+    ;;
+    *)
+	usage
+	;;
+esac
+
+# The upstream branch to work on.
+branch=origin/master
+
+# The commit which added the support/ directory.
+initial_commit=c23de0aacbeaa7a091609b35764bed931475a16d
+
+# We backport the support directory and this script.  Directories need
+# to end in a /.
+patch_targets="support/ scripts/backport-support.sh"
+
+latest_commit="$(git log --max-count=1 --pretty=format:%H "$branch" -- \
+  $patch_targets)"
+
+# Simplify the branch name somewhat for reporting.
+branch_name="$(echo "$branch" | sed s,^origin/,,)"
+
+command_patch () {
+    cat <<EOF
+This patch creates the contents of the support/ directory up to this
+upstream commit on the $branch_name branch:
+
+EOF
+    git log --max-count=1 "$latest_commit"
+    echo
+    git diff "$initial_commit"^.."$latest_commit" $patch_targets
+    echo "# Before applying the patch, run this command:" >&2
+    echo "# rm -rf $patch_targets" >&2
+}
+
+command_commit () {
+    git status --porcelain | while read line ; do
+	echo "error: working copy is not clean, cannot commit" >&2
+	exit 1
+    done
+    for path in $patch_targets; do
+	echo "# Processing $path" >&2
+	case "$path" in
+	    [a-zA-Z0-9]*/)
+		# Directory.
+		git rm --cached --ignore-unmatch -r "$path"
+		rm -rf "$path"
+		git read-tree --prefix="$path" "$latest_commit":"$path"
+		git checkout "$path"
+		;;
+	    *)
+		# File.
+		git show "$latest_commit":"$path" > "$path"
+		git add "$path"
+	esac
+    done
+    git commit -m "Synchronize support/ infrastructure with $branch_name
+
+This commit updates the support/ subdirectory to
+commit $latest_commit
+on the $branch_name branch.
+"
+}
+
+command_$command
diff --git a/support/Makefile b/support/Makefile
new file mode 100644
index 0000000..20b0343
--- /dev/null
+++ b/support/Makefile
@@ -0,0 +1,146 @@
+# Makefile for support library, used only at build and test time
+# Copyright (C) 2016-2017 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.
+
+subdir := support
+
+include ../Makeconfig
+
+extra-libs := libsupport
+extra-libs-others = $(extra-libs)
+extra-libs-noinstall := $(extra-libs)
+
+libsupport-routines = \
+  check \
+  check_addrinfo \
+  check_dns_packet \
+  check_hostent \
+  check_netent \
+  delayed_exit \
+  ignore_stderr \
+  oom_error \
+  resolv_test \
+  set_fortify_handler \
+  support-xstat \
+  support_become_root \
+  support_can_chroot \
+  support_capture_subprocess \
+  support_capture_subprocess_check \
+  support_enter_network_namespace \
+  support_format_address_family \
+  support_format_addrinfo \
+  support_format_dns_packet \
+  support_format_herrno \
+  support_format_hostent \
+  support_format_netent \
+  support_isolate_in_subprocess \
+  support_record_failure \
+  support_run_diff \
+  support_shared_allocate \
+  support_write_file_string \
+  support_test_main \
+  support_test_verify_impl \
+  temp_file \
+  write_message \
+  xaccept \
+  xaccept4 \
+  xasprintf \
+  xbind \
+  xcalloc \
+  xchroot \
+  xclose \
+  xconnect \
+  xdup2 \
+  xfclose \
+  xfopen \
+  xfork \
+  xgetsockname \
+  xlisten \
+  xmalloc \
+  xmemstream \
+  xmkdir \
+  xmmap \
+  xmunmap \
+  xopen \
+  xpipe \
+  xpoll \
+  xpthread_attr_destroy \
+  xpthread_attr_init \
+  xpthread_attr_setdetachstate \
+  xpthread_attr_setstacksize \
+  xpthread_barrier_destroy \
+  xpthread_barrier_init \
+  xpthread_barrier_wait \
+  xpthread_cancel \
+  xpthread_check_return \
+  xpthread_cond_wait \
+  xpthread_create \
+  xpthread_detach \
+  xpthread_join \
+  xpthread_mutex_consistent \
+  xpthread_mutex_destroy \
+  xpthread_mutex_init \
+  xpthread_mutex_lock \
+  xpthread_mutex_unlock \
+  xpthread_mutexattr_destroy \
+  xpthread_mutexattr_init \
+  xpthread_mutexattr_setprotocol \
+  xpthread_mutexattr_setpshared \
+  xpthread_mutexattr_setrobust \
+  xpthread_mutexattr_settype \
+  xpthread_once \
+  xpthread_sigmask \
+  xpthread_spin_lock \
+  xpthread_spin_unlock \
+  xrealloc \
+  xrecvfrom \
+  xsendto \
+  xsetsockopt \
+  xsocket \
+  xstrdup \
+  xwaitpid \
+  xwrite \
+
+libsupport-static-only-routines := $(libsupport-routines)
+# Only build one variant of the library.
+libsupport-inhibit-o := .os
+ifeq ($(build-shared),yes)
+libsupport-inhibit-o += .o
+endif
+
+tests = \
+  README-testing \
+  tst-support-namespace \
+  tst-support_capture_subprocess \
+  tst-support_format_dns_packet \
+  tst-support_record_failure \
+
+ifeq ($(run-built-tests),yes)
+tests-special = \
+  $(objpfx)tst-support_record_failure-2.out
+
+$(objpfx)tst-support_record_failure-2.out: tst-support_record_failure-2.sh \
+  $(objpfx)tst-support_record_failure
+	$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
+	  '$(run-program-env)' '$(test-program-prefix-after-env)' \
+	  > $@; \
+	$(evaluate-test)
+endif
+
+$(objpfx)tst-support_format_dns_packet: $(common-objpfx)resolv/libresolv.so
+
+include ../Rules
diff --git a/support/README b/support/README
new file mode 100644
index 0000000..476cfcd
--- /dev/null
+++ b/support/README
@@ -0,0 +1,29 @@
+This subdirectory contains infrastructure which is not put into
+installed libraries, but may be linked into programs (installed or
+not) and tests.
+
+# Error-checking wrappers
+
+These wrappers test for error return codes an terminate the process on
+error.  They are declared in these header files:
+
+* support.h
+* xsignal.h
+* xthread.h
+
+In general, new wrappers should be added to support.h if possible.
+However, support.h must remain fully compatible with C90 and therefore
+cannot include headers which use identifers not reserved in C90.  If
+the wrappers need additional types, additional headers such as
+signal.h need to be introduced.
+
+# Test framework
+
+The test framework provides a main program for tests, including a
+timeout for hanging tests.  See README-testing.c for a minimal
+example, and test-driver.c for details how to use it.  The following
+header files provide related declarations:
+
+* check.h
+* temp_file.h
+* test-driver.h
diff --git a/support/README-testing.c b/support/README-testing.c
new file mode 100644
index 0000000..9d289c3
--- /dev/null
+++ b/support/README-testing.c
@@ -0,0 +1,19 @@
+/* This file contains an example test case which shows minimal use of
+   the test framework.  Additional testing hooks are described in
+   <support/test-driver.c>.  */
+
+/* This function will be called from the test driver.  */
+static int
+do_test (void)
+{
+  if (3 == 5)
+    /* Indicate failure.  */
+    return 1;
+  else
+    /* Indicate success.  */
+    return 0;
+}
+
+/* This file references do_test above and contains the definition of
+   the main function.  */
+#include <support/test-driver.c>
diff --git a/support/capture_subprocess.h b/support/capture_subprocess.h
new file mode 100644
index 0000000..43caf9b
--- /dev/null
+++ b/support/capture_subprocess.h
@@ -0,0 +1,61 @@
+/* Capture output from a subprocess.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_CAPTURE_SUBPROCESS_H
+#define SUPPORT_CAPTURE_SUBPROCESS_H
+
+#include <support/xmemstream.h>
+
+struct support_capture_subprocess
+{
+  struct xmemstream out;
+  struct xmemstream err;
+  int status;
+};
+
+/* Invoke CALLBACK (CLOSURE) in a subprocess and capture standard
+   output, standard error, and the exit status.  The out.buffer and
+   err.buffer members in the result are null-terminated strings which
+   can be examined by the caller (out.out and err.out are NULL).  */
+struct support_capture_subprocess support_capture_subprocess
+  (void (*callback) (void *), void *closure);
+
+/* Deallocate the subprocess data captured by
+   support_capture_subprocess.  */
+void support_capture_subprocess_free (struct support_capture_subprocess *);
+
+enum support_capture_allow
+{
+  /* No output is allowed.  */
+  sc_allow_none = 0x01,
+  /* Output to stdout is permitted.  */
+  sc_allow_stdout = 0x02,
+  /* Output to standard error is permitted.  */
+  sc_allow_stderr = 0x04,
+};
+
+/* Check that the subprocess exited with STATUS and that only the
+   allowed outputs happened.  ALLOWED is a combination of
+   support_capture_allow flags.  Report errors under the CONTEXT
+   message.  */
+void support_capture_subprocess_check (struct support_capture_subprocess *,
+                                       const char *context, int status,
+                                       int allowed)
+  __attribute__ ((nonnull (1, 2)));
+
+#endif /* SUPPORT_CAPTURE_SUBPROCESS_H */
diff --git a/support/check.c b/support/check.c
new file mode 100644
index 0000000..592f2bc
--- /dev/null
+++ b/support/check.c
@@ -0,0 +1,57 @@
+/* Support code for reporting test results.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/test-driver.h>
+
+static void
+print_failure (const char *file, int line, const char *format, va_list ap)
+{
+  printf ("error: %s:%d: ", file, line);
+  vprintf (format, ap);
+  puts ("");
+}
+
+int
+support_print_failure_impl (const char *file, int line,
+                            const char *format, ...)
+{
+  support_record_failure ();
+  va_list ap;
+  va_start (ap, format);
+  print_failure (file, line, format, ap);
+  va_end (ap);
+  return 1;
+}
+
+void
+support_exit_failure_impl (int status, const char *file, int line,
+                           const char *format, ...)
+{
+  if (status != EXIT_SUCCESS && status != EXIT_UNSUPPORTED)
+    support_record_failure ();
+  va_list ap;
+  va_start (ap, format);
+  print_failure (file, line, format, ap);
+  va_end (ap);
+  exit (status);
+}
diff --git a/support/check.h b/support/check.h
new file mode 100644
index 0000000..1d244a3
--- /dev/null
+++ b/support/check.h
@@ -0,0 +1,94 @@
+/* Functionality for reporting test results.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_CHECK_H
+#define SUPPORT_CHECK_H
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Record a test failure, print the failure message to standard output
+   and return 1.  */
+#define FAIL_RET(...) \
+  return support_print_failure_impl (__FILE__, __LINE__, __VA_ARGS__)
+
+/* Print the failure message and terminate the process with STATUS.
+   Record a the process as failed if STATUS is neither EXIT_SUCCESS
+   nor EXIT_UNSUPPORTED.  */
+#define FAIL_EXIT(status, ...) \
+  support_exit_failure_impl (status, __FILE__, __LINE__, __VA_ARGS__)
+
+/* Record a test failure, print the failure message and terminate with
+   exit status 1.  */
+#define FAIL_EXIT1(...) \
+  support_exit_failure_impl (1, __FILE__, __LINE__, __VA_ARGS__)
+
+/* Print failure message and terminate with as unsupported test (exit
+   status of 77).  */
+#define FAIL_UNSUPPORTED(...) \
+  support_exit_failure_impl (77, __FILE__, __LINE__, __VA_ARGS__)
+
+/* Record a test failure (but continue executing) if EXPR evaluates to
+   false.  */
+#define TEST_VERIFY(expr)                                       \
+  ({                                                            \
+    if (expr)                                                   \
+      ;                                                         \
+    else                                                        \
+      support_test_verify_impl (-1, __FILE__, __LINE__, #expr); \
+  })
+
+/* Record a test failure and exit if EXPR evaluates to false.  */
+#define TEST_VERIFY_EXIT(expr)                                  \
+  ({                                                            \
+    if (expr)                                                   \
+      ;                                                         \
+    else                                                        \
+      support_test_verify_impl (1, __FILE__, __LINE__, #expr);  \
+  })
+
+int support_print_failure_impl (const char *file, int line,
+                                const char *format, ...)
+  __attribute__ ((nonnull (1), format (printf, 3, 4)));
+void support_exit_failure_impl (int exit_status,
+                                const char *file, int line,
+                                const char *format, ...)
+  __attribute__ ((noreturn, nonnull (2), format (printf, 4, 5)));
+void support_test_verify_impl (int status, const char *file, int line,
+                               const char *expr);
+
+/* Record a test failure.  This function returns and does not
+   terminate the process.  The failure counter is stored in a shared
+   memory mapping, so that failures reported in child processes are
+   visible to the parent process and test driver.  This function
+   depends on initialization by an ELF constructor, so it can only be
+   invoked after the test driver has run.  Note that this function
+   does not support reporting failures from a DSO.  */
+void support_record_failure (void);
+
+/* Internal function called by the test driver.  */
+int support_report_failure (int status)
+  __attribute__ ((weak, warn_unused_result));
+
+/* Internal function used to test the failure recording framework.  */
+void support_record_failure_reset (void);
+
+__END_DECLS
+
+#endif /* SUPPORT_CHECK_H */
diff --git a/support/check_addrinfo.c b/support/check_addrinfo.c
new file mode 100644
index 0000000..55895ac
--- /dev/null
+++ b/support/check_addrinfo.c
@@ -0,0 +1,42 @@
+/* Compare struct addrinfo values against a formatted string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check_nss.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/format_nss.h>
+#include <support/run_diff.h>
+
+void
+check_addrinfo (const char *query_description, struct addrinfo *ai, int ret,
+                const char *expected)
+{
+  char *formatted = support_format_addrinfo (ai, ret);
+  if (strcmp (formatted, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: addrinfo comparison failure\n");
+      if (query_description != NULL)
+        printf ("query: %s\n", query_description);
+      support_run_diff ("expected", expected,
+                        "actual", formatted);
+    }
+  free (formatted);
+}
diff --git a/support/check_dns_packet.c b/support/check_dns_packet.c
new file mode 100644
index 0000000..d2a31be
--- /dev/null
+++ b/support/check_dns_packet.c
@@ -0,0 +1,42 @@
+/* Check that a DNS packet buffer has the expected contents.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check_nss.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/format_nss.h>
+#include <support/run_diff.h>
+
+void
+check_dns_packet (const char *query_description,
+                  const unsigned char *buffer, size_t length,
+                  const char *expected)
+{
+  char *formatted = support_format_dns_packet (buffer, length);
+  if (strcmp (formatted, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: packet comparison failure\n");
+      if (query_description != NULL)
+        printf ("query: %s\n", query_description);
+      support_run_diff ("expected", expected, "actual", formatted);
+    }
+  free (formatted);
+}
diff --git a/support/check_hostent.c b/support/check_hostent.c
new file mode 100644
index 0000000..890d672
--- /dev/null
+++ b/support/check_hostent.c
@@ -0,0 +1,42 @@
+/* Compare struct hostent values against a formatted string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check_nss.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/format_nss.h>
+#include <support/run_diff.h>
+
+void
+check_hostent (const char *query_description, struct hostent *h,
+               const char *expected)
+{
+  char *formatted = support_format_hostent (h);
+  if (strcmp (formatted, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: hostent comparison failure\n");
+      if (query_description != NULL)
+        printf ("query: %s\n", query_description);
+      support_run_diff ("expected", expected,
+                        "actual", formatted);
+    }
+  free (formatted);
+}
diff --git a/support/check_netent.c b/support/check_netent.c
new file mode 100644
index 0000000..daa3083
--- /dev/null
+++ b/support/check_netent.c
@@ -0,0 +1,42 @@
+/* Compare struct netent values against a formatted string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check_nss.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/format_nss.h>
+#include <support/run_diff.h>
+
+void
+check_netent (const char *query_description, struct netent *e,
+              const char *expected)
+{
+  char *formatted = support_format_netent (e);
+  if (strcmp (formatted, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: netent comparison failure\n");
+      if (query_description != NULL)
+        printf ("query: %s\n", query_description);
+      support_run_diff ("expected", expected,
+                        "actual", formatted);
+    }
+  free (formatted);
+}
diff --git a/support/check_nss.h b/support/check_nss.h
new file mode 100644
index 0000000..2893f2c
--- /dev/null
+++ b/support/check_nss.h
@@ -0,0 +1,42 @@
+/* Test verification functions for NSS- and DNS-related data.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_CHECK_NSS_H
+#define SUPPORT_CHECK_NSS_H
+
+#include <netdb.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Compare the data structures against the expected values (which have
+   to be formatted according to the support_format_* functions in
+   <support/format_nss.h>).  If there is a difference, a delayed test
+   failure is recorded, and a diff is written to standard output.  */
+void check_addrinfo (const char *query_description,
+                     struct addrinfo *, int ret, const char *expected);
+void check_dns_packet (const char *query_description,
+                       const unsigned char *, size_t, const char *expected);
+void check_hostent (const char *query_description,
+                    struct hostent *, const char *expected);
+void check_netent (const char *query_description,
+                   struct netent *, const char *expected);
+
+__END_DECLS
+
+#endif  /* SUPPORT_CHECK_NSS_H */
diff --git a/support/delayed_exit.c b/support/delayed_exit.c
new file mode 100644
index 0000000..67442f9
--- /dev/null
+++ b/support/delayed_exit.c
@@ -0,0 +1,55 @@
+/* Time-triggered process termination.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+#include <support/xsignal.h>
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <time.h>
+
+static void *
+delayed_exit_thread (void *seconds_as_ptr)
+{
+  int seconds = (uintptr_t) seconds_as_ptr;
+  struct timespec delay = { seconds, 0 };
+  struct timespec remaining = { 0 };
+  if (nanosleep (&delay, &remaining) != 0)
+    FAIL_EXIT1 ("nanosleep: %m");
+  /* Exit the process sucessfully.  */
+  exit (0);
+  return NULL;
+}
+
+void
+delayed_exit (int seconds)
+{
+  /* Create the new thread with all signals blocked.  */
+  sigset_t all_blocked;
+  sigfillset (&all_blocked);
+  sigset_t old_set;
+  xpthread_sigmask (SIG_SETMASK, &all_blocked, &old_set);
+  /* Create a detached thread. */
+  pthread_t thr = xpthread_create
+    (NULL, delayed_exit_thread, (void *) (uintptr_t) seconds);
+  xpthread_detach (thr);
+  /* Restore the original signal mask.  */
+  xpthread_sigmask (SIG_SETMASK, &old_set, NULL);
+}
diff --git a/support/format_nss.h b/support/format_nss.h
new file mode 100644
index 0000000..fb4597c
--- /dev/null
+++ b/support/format_nss.h
@@ -0,0 +1,41 @@
+/* String formatting functions for NSS- and DNS-related data.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_FORMAT_NSS_H
+#define SUPPORT_FORMAT_NSS_H
+
+#include <netdb.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* The following functions format their arguments as human-readable
+   strings (which can span multiple lines).  The caller must free the
+   returned buffer.  For NULL pointers or failure status arguments,
+   error variables such as h_errno and errno are included in the
+   result.  */
+char *support_format_address_family (int);
+char *support_format_addrinfo (struct addrinfo *, int ret);
+char *support_format_dns_packet (const unsigned char *buffer, size_t length);
+char *support_format_herrno (int);
+char *support_format_hostent (struct hostent *);
+char *support_format_netent (struct netent *);
+
+__END_DECLS
+
+#endif  /* SUPPORT_FORMAT_NSS_H */
diff --git a/support/ignore_stderr.c b/support/ignore_stderr.c
new file mode 100644
index 0000000..7b77a2c
--- /dev/null
+++ b/support/ignore_stderr.c
@@ -0,0 +1,38 @@
+/* Avoid all the buffer overflow messages on stderr.
+   Copyright (C) 2015-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <fcntl.h>
+#include <paths.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+void
+ignore_stderr (void)
+{
+  int fd = open (_PATH_DEVNULL, O_WRONLY);
+  if (fd == -1)
+    close (STDERR_FILENO);
+  else
+    {
+      dup2 (fd, STDERR_FILENO);
+      close (fd);
+    }
+  setenv ("LIBC_FATAL_STDERR_", "1", 1);
+}
diff --git a/support/namespace.h b/support/namespace.h
new file mode 100644
index 0000000..e1ccaa1
--- /dev/null
+++ b/support/namespace.h
@@ -0,0 +1,65 @@
+/* Entering namespaces for test case isolation.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_NAMESPACE_H
+#define SUPPORT_NAMESPACE_H
+
+#include <stdbool.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Attempts to become root (or acquire root-like privileges), possibly
+   with the help of user namespaces.  Return true if (restricted) root
+   privileges could be attained in some way.  Print diagnostics to
+   standard output.
+
+   Note that this function generally has to be called before a process
+   becomes multi-threaded, otherwise it may fail with insufficient
+   privileges on systems which would support this operation for
+   single-threaded processes.  */
+bool support_become_root (void);
+
+/* Return true if this process can perform a chroot operation.  In
+   general, this is only possible if support_become_root has been
+   called.  Note that the actual test is performed in a subprocess,
+   after fork, so that the file system root of the original process is
+   not changed.  */
+bool support_can_chroot (void);
+
+/* Enter a network namespace (and a UTS namespace if possible) and
+   configure the loopback interface.  Return true if a network
+   namespace could be created.  Print diagnostics to standard output.
+   If a network namespace could be created, but networking in it could
+   not be configured, terminate the process.  It is recommended to
+   call support_become_root before this function so that the process
+   has sufficient privileges.  */
+bool support_enter_network_namespace (void);
+
+/* Return true if support_enter_network_namespace managed to enter a
+   UTS namespace.  */
+bool support_in_uts_namespace (void);
+
+/* Invoke CALLBACK (CLOSURE) in a subprocess created using fork.
+   Terminate the calling process if the subprocess exits with a
+   non-zero exit status.  */
+void support_isolate_in_subprocess (void (*callback) (void *), void *closure);
+
+__END_DECLS
+
+#endif
diff --git a/support/oom_error.c b/support/oom_error.c
new file mode 100644
index 0000000..7816978
--- /dev/null
+++ b/support/oom_error.c
@@ -0,0 +1,29 @@
+/* Reporting out-of-memory errors.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+void
+oom_error (const char *function, size_t size)
+{
+  printf ("%s: unable to allocate %zu bytes: %m\n", function, size);
+  exit (1);
+}
diff --git a/support/resolv_test.c b/support/resolv_test.c
new file mode 100644
index 0000000..050cd71
--- /dev/null
+++ b/support/resolv_test.c
@@ -0,0 +1,1202 @@
+/* DNS test framework and libresolv redirection.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/resolv_test.h>
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <nss.h>
+#include <resolv.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+#include <support/xsocket.h>
+#include <support/xthread.h>
+#include <support/xunistd.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+/* Response builder.  */
+
+enum
+  {
+    max_response_length = 65536
+  };
+
+/* List of pointers to be freed.  The hash table implementation
+   (struct hsearch_data) does not provide a way to deallocate all
+   objects, so this approach is used to avoid memory leaks.  */
+struct to_be_freed
+{
+  struct to_be_freed *next;
+  void *ptr;
+};
+
+struct resolv_response_builder
+{
+  const unsigned char *query_buffer;
+  size_t query_length;
+
+  size_t offset;                /* Bytes written so far in buffer.  */
+  ns_sect section;              /* Current section in the DNS packet.  */
+  unsigned int truncate_bytes;  /* Bytes to remove at end of response. */
+  bool drop;                    /* Discard generated response.  */
+  bool close;                   /* Close TCP client connection.  */
+
+  /* Offset of the two-byte RDATA length field in the currently
+     written RDATA sub-structure.  0 if no RDATA is being written.  */
+  size_t current_rdata_offset;
+
+  /* Hash table for locating targets for label compression.  */
+  struct hsearch_data compression_offsets;
+  /* List of pointers which need to be freed.  Used for domain names
+     involved in label compression.  */
+  struct to_be_freed *to_be_freed;
+
+  /* Must be last.  Not zeroed for performance reasons.  */
+  unsigned char buffer[max_response_length];
+};
+
+/* Response builder. */
+
+/* Add a pointer to the list of pointers to be freed when B is
+   deallocated.  */
+static void
+response_push_pointer_to_free (struct resolv_response_builder *b, void *ptr)
+{
+  if (ptr == NULL)
+    return;
+  struct to_be_freed *e = xmalloc (sizeof (*e));
+  *e = (struct to_be_freed) {b->to_be_freed, ptr};
+  b->to_be_freed = e;
+}
+
+void
+resolv_response_init (struct resolv_response_builder *b,
+                      struct resolv_response_flags flags)
+{
+  if (b->offset > 0)
+    FAIL_EXIT1 ("response_init: called at offset %zu", b->offset);
+  if (b->query_length < 12)
+    FAIL_EXIT1 ("response_init called for a query of size %zu",
+                b->query_length);
+  if (flags.rcode > 15)
+    FAIL_EXIT1 ("response_init: invalid RCODE %u", flags.rcode);
+
+  /* Copy the transaction ID.  */
+  b->buffer[0] = b->query_buffer[0];
+  b->buffer[1] = b->query_buffer[1];
+
+  /* Initialize the flags.  */
+  b->buffer[2] = 0x80;                       /* Mark as response.   */
+  b->buffer[2] |= b->query_buffer[2] & 0x01; /* Copy the RD bit.  */
+  if (flags.tc)
+    b->buffer[2] |= 0x02;
+  b->buffer[3] = 0x80 | flags.rcode; /* Always set RA.  */
+
+  /* Fill in the initial section count values.  */
+  b->buffer[4] = flags.qdcount >> 8;
+  b->buffer[5] = flags.qdcount;
+  b->buffer[6] = flags.ancount >> 8;
+  b->buffer[7] = flags.ancount;
+  b->buffer[8] = flags.nscount >> 8;
+  b->buffer[9] = flags.nscount;
+  b->buffer[10] = flags.adcount >> 8;
+  b->buffer[11] = flags.adcount;
+
+  b->offset = 12;
+}
+
+void
+resolv_response_section (struct resolv_response_builder *b, ns_sect section)
+{
+  if (b->offset == 0)
+    FAIL_EXIT1 ("resolv_response_section: response_init not called before");
+  if (section < b->section)
+    FAIL_EXIT1 ("resolv_response_section: cannot go back to previous section");
+  b->section = section;
+}
+
+/* Add a single byte to B.  */
+static inline void
+response_add_byte (struct resolv_response_builder *b, unsigned char ch)
+{
+  if (b->offset == max_response_length)
+    FAIL_EXIT1 ("DNS response exceeds 64 KiB limit");
+  b->buffer[b->offset] = ch;
+  ++b->offset;
+}
+
+/* Add a 16-bit word VAL to B, in big-endian format.  */
+static void
+response_add_16 (struct resolv_response_builder *b, uint16_t val)
+{
+  response_add_byte (b, val >> 8);
+  response_add_byte (b, val);
+}
+
+/* Increment the pers-section record counter in the packet header.  */
+static void
+response_count_increment (struct resolv_response_builder *b)
+{
+  unsigned int offset = b->section;
+  offset = 4 + 2 * offset;
+  ++b->buffer[offset + 1];
+  if (b->buffer[offset + 1] == 0)
+    {
+      /* Carry.  */
+      ++b->buffer[offset];
+      if (b->buffer[offset] == 0)
+        /* Overflow.  */
+        FAIL_EXIT1 ("too many records in section");
+    }
+}
+
+void
+resolv_response_add_question (struct resolv_response_builder *b,
+                              const char *name, uint16_t class, uint16_t type)
+{
+  if (b->offset == 0)
+    FAIL_EXIT1 ("resolv_response_add_question: "
+                "resolv_response_init not called");
+  if (b->section != ns_s_qd)
+    FAIL_EXIT1 ("resolv_response_add_question: "
+                "must be called in the question section");
+
+  resolv_response_add_name (b, name);
+  response_add_16 (b, type);
+  response_add_16 (b, class);
+
+  response_count_increment (b);
+}
+
+void
+resolv_response_add_name (struct resolv_response_builder *b,
+                          const char *const origname)
+{
+  /* Normalized name.  */
+  char *name;
+  /* Normalized name with case preserved.  */
+  char *name_case;
+  {
+    size_t namelen = strlen (origname);
+    /* Remove trailing dots.  FIXME: Handle trailing quoted dots.  */
+    while (namelen > 0 && origname[namelen - 1] == '.')
+      --namelen;
+    name = xmalloc (namelen + 1);
+    name_case = xmalloc (namelen + 1);
+    /* Copy and convert to lowercase.  FIXME: This needs to normalize
+       escaping as well.  */
+    for (size_t i = 0; i < namelen; ++i)
+      {
+        char ch = origname[i];
+        name_case[i] = ch;
+        if ('A' <= ch && ch <= 'Z')
+          ch = ch - 'A' + 'a';
+        name[i] = ch;
+      }
+    name[namelen] = 0;
+    name_case[namelen] = 0;
+  }
+  char *name_start = name;
+  char *name_case_start = name_case;
+
+  bool compression = false;
+  while (*name)
+    {
+      /* Search for a previous name we can reference.  */
+      ENTRY new_entry =
+        {
+          .key = name,
+          .data = (void *) (uintptr_t) b->offset,
+        };
+
+      /* If the label can be a compression target because it is at a
+         reachable offset, add it to the hash table.  */
+      ACTION action;
+      if (b->offset < (1 << 12))
+        action = ENTER;
+      else
+        action = FIND;
+
+      /* Search for known compression offsets in the hash table.  */
+      ENTRY *e;
+      if (hsearch_r (new_entry, action, &e, &b->compression_offsets) == 0)
+        {
+          if (action == FIND && errno == ESRCH)
+            /* Fall through.  */
+            e = NULL;
+          else
+            FAIL_EXIT1 ("hsearch_r failure in name compression: %m");
+        }
+
+      /* The name is known.  Reference the previous location.  */
+      if (e != NULL && e->data != new_entry.data)
+        {
+          size_t old_offset = (uintptr_t) e->data;
+          response_add_byte (b, 0xC0 | (old_offset >> 8));
+          response_add_byte (b, old_offset);
+          compression = true;
+          break;
+        }
+
+      /* The name does not exist yet.  Write one label.  First, add
+         room for the label length.  */
+      size_t buffer_label_offset = b->offset;
+      response_add_byte (b, 0);
+
+      /* Copy the label.  */
+      while (true)
+        {
+          char ch = *name_case;
+          if (ch == '\0')
+            break;
+          ++name;
+          ++name_case;
+          if (ch == '.')
+            break;
+          /* FIXME: Handle escaping.  */
+          response_add_byte (b, ch);
+        }
+
+      /* Patch in the label length.  */
+      size_t label_length = b->offset - buffer_label_offset - 1;
+      if (label_length == 0)
+        FAIL_EXIT1 ("empty label in name compression: %s", origname);
+      if (label_length > 63)
+        FAIL_EXIT1 ("label too long in name compression: %s", origname);
+      b->buffer[buffer_label_offset] = label_length;
+
+      /* Continue with the tail of the name and the next label.  */
+    }
+
+  if (compression)
+    {
+      /* If we found an immediate match for the name, we have not put
+         it into the hash table, and can free it immediately.  */
+      if (name == name_start)
+        free (name_start);
+      else
+        response_push_pointer_to_free (b, name_start);
+    }
+  else
+    {
+      /* Terminate the sequence of labels.  With compression, this is
+         implicit in the compression reference.  */
+      response_add_byte (b, 0);
+      response_push_pointer_to_free (b, name_start);
+    }
+
+  free (name_case_start);
+}
+
+void
+resolv_response_open_record (struct resolv_response_builder *b,
+                             const char *name,
+                             uint16_t class, uint16_t type, uint32_t ttl)
+{
+  if (b->section == ns_s_qd)
+    FAIL_EXIT1 ("resolv_response_open_record called in question section");
+  if (b->current_rdata_offset != 0)
+    FAIL_EXIT1 ("resolv_response_open_record called with open record");
+
+  resolv_response_add_name (b, name);
+  response_add_16 (b, type);
+  response_add_16 (b, class);
+  response_add_16 (b, ttl >> 16);
+  response_add_16 (b, ttl);
+
+  b->current_rdata_offset = b->offset;
+  /* Add room for the RDATA length.  */
+  response_add_16 (b, 0);
+}
+
+
+void
+resolv_response_close_record (struct resolv_response_builder *b)
+{
+  size_t rdata_offset = b->current_rdata_offset;
+  if (rdata_offset == 0)
+    FAIL_EXIT1 ("response_close_record called without open record");
+  size_t rdata_length = b->offset - rdata_offset - 2;
+  if (rdata_length > 65535)
+    FAIL_EXIT1 ("RDATA length %zu exceeds limit", rdata_length);
+  b->buffer[rdata_offset] = rdata_length >> 8;
+  b->buffer[rdata_offset + 1] = rdata_length;
+  response_count_increment (b);
+  b->current_rdata_offset = 0;
+}
+
+void
+resolv_response_add_data (struct resolv_response_builder *b,
+                          const void *data, size_t length)
+{
+  size_t remaining = max_response_length - b->offset;
+  if (remaining < length)
+    FAIL_EXIT1 ("resolv_response_add_data: not enough room for %zu bytes",
+                length);
+  memcpy (b->buffer + b->offset, data, length);
+  b->offset += length;
+}
+
+void
+resolv_response_drop (struct resolv_response_builder *b)
+{
+  b->drop = true;
+}
+
+void
+resolv_response_close (struct resolv_response_builder *b)
+{
+  b->close = true;
+}
+
+void
+resolv_response_truncate_data (struct resolv_response_builder *b, size_t count)
+{
+  if (count > 65535)
+    FAIL_EXIT1 ("resolv_response_truncate_data: argument too large: %zu",
+                count);
+  b->truncate_bytes = count;
+}
+
+
+size_t
+resolv_response_length (const struct resolv_response_builder *b)
+{
+  return b->offset;
+}
+
+unsigned char *
+resolv_response_buffer (const struct resolv_response_builder *b)
+{
+  unsigned char *result = xmalloc (b->offset);
+  memcpy (result, b->buffer, b->offset);
+  return result;
+}
+
+static struct resolv_response_builder *
+response_builder_allocate
+  (const unsigned char *query_buffer, size_t query_length)
+{
+  struct resolv_response_builder *b = xmalloc (sizeof (*b));
+  memset (b, 0, offsetof (struct resolv_response_builder, buffer));
+  b->query_buffer = query_buffer;
+  b->query_length = query_length;
+  TEST_VERIFY_EXIT (hcreate_r (10000, &b->compression_offsets) != 0);
+  return b;
+}
+
+static void
+response_builder_free (struct resolv_response_builder *b)
+{
+  struct to_be_freed *current = b->to_be_freed;
+  while (current != NULL)
+    {
+      struct to_be_freed *next = current->next;
+      free (current->ptr);
+      free (current);
+      current = next;
+    }
+  hdestroy_r (&b->compression_offsets);
+  free (b);
+}
+
+/* DNS query processing. */
+
+/* Data extracted from the question section of a DNS packet.  */
+struct query_info
+{
+  char qname[MAXDNAME];
+  uint16_t qclass;
+  uint16_t qtype;
+  struct resolv_edns_info edns;
+};
+
+/* Update *INFO from the specified DNS packet.  */
+static void
+parse_query (struct query_info *info,
+             const unsigned char *buffer, size_t length)
+{
+  HEADER hd;
+  _Static_assert (sizeof (hd) == 12, "DNS header size");
+  if (length < sizeof (hd))
+    FAIL_EXIT1 ("malformed DNS query: too short: %zu bytes", length);
+  memcpy (&hd, buffer, sizeof (hd));
+
+  if (ntohs (hd.qdcount) != 1)
+    FAIL_EXIT1 ("malformed DNS query: wrong question count: %d",
+                (int) ntohs (hd.qdcount));
+  if (ntohs (hd.ancount) != 0)
+    FAIL_EXIT1 ("malformed DNS query: wrong answer count: %d",
+                (int) ntohs (hd.ancount));
+  if (ntohs (hd.nscount) != 0)
+    FAIL_EXIT1 ("malformed DNS query: wrong authority count: %d",
+                (int) ntohs (hd.nscount));
+  if (ntohs (hd.arcount) > 1)
+    FAIL_EXIT1 ("malformed DNS query: wrong additional count: %d",
+                (int) ntohs (hd.arcount));
+
+  int ret = dn_expand (buffer, buffer + length, buffer + sizeof (hd),
+                       info->qname, sizeof (info->qname));
+  if (ret < 0)
+    FAIL_EXIT1 ("malformed DNS query: cannot uncompress QNAME");
+
+  /* Obtain QTYPE and QCLASS.  */
+  size_t remaining = length - (12 + ret);
+  struct
+  {
+    uint16_t qtype;
+    uint16_t qclass;
+  } qtype_qclass;
+  if (remaining < sizeof (qtype_qclass))
+    FAIL_EXIT1 ("malformed DNS query: "
+                "query lacks QCLASS/QTYPE, QNAME: %s", info->qname);
+  memcpy (&qtype_qclass, buffer + 12 + ret, sizeof (qtype_qclass));
+  info->qclass = ntohs (qtype_qclass.qclass);
+  info->qtype = ntohs (qtype_qclass.qtype);
+
+  memset (&info->edns, 0, sizeof (info->edns));
+  if (ntohs (hd.arcount) > 0)
+    {
+      /* Parse EDNS record.  */
+      struct __attribute__ ((packed, aligned (1)))
+      {
+        uint8_t root;
+        uint16_t rtype;
+        uint16_t payload;
+        uint8_t edns_extended_rcode;
+        uint8_t edns_version;
+        uint16_t flags;
+        uint16_t rdatalen;
+      } rr;
+      _Static_assert (sizeof (rr) == 11, "EDNS record size");
+
+      if (remaining < 4 + sizeof (rr))
+        FAIL_EXIT1 ("mailformed DNS query: no room for EDNS record");
+      memcpy (&rr, buffer + 12 + ret + 4, sizeof (rr));
+      if (rr.root != 0)
+        FAIL_EXIT1 ("malformed DNS query: invalid OPT RNAME: %d\n", rr.root);
+      if (rr.rtype != htons (41))
+        FAIL_EXIT1 ("malformed DNS query: invalid OPT type: %d\n",
+                    ntohs (rr.rtype));
+      info->edns.active = true;
+      info->edns.extended_rcode = rr.edns_extended_rcode;
+      info->edns.version = rr.edns_version;
+      info->edns.flags = ntohs (rr.flags);
+      info->edns.payload_size = ntohs (rr.payload);
+    }
+}
+
+
+/* Main testing framework.  */
+
+/* Per-server information.  One struct is allocated for each test
+   server.  */
+struct resolv_test_server
+{
+  /* Local address of the server.  UDP and TCP use the same port.  */
+  struct sockaddr_in address;
+
+  /* File descriptor of the UDP server, or -1 if this server is
+     disabled.  */
+  int socket_udp;
+
+  /* File descriptor of the TCP server, or -1 if this server is
+     disabled.  */
+  int socket_tcp;
+
+  /* Counter of the number of responses processed so far.  */
+  size_t response_number;
+
+  /* Thread handles for the server threads (if not disabled in the
+     configuration).  */
+  pthread_t thread_udp;
+  pthread_t thread_tcp;
+};
+
+/* Main struct for keeping track of libresolv redirection and
+   testing.  */
+struct resolv_test
+{
+  /* After initialization, any access to the struct must be performed
+     while this lock is acquired.  */
+  pthread_mutex_t lock;
+
+  /* Data for each test server. */
+  struct resolv_test_server servers[resolv_max_test_servers];
+
+  /* Used if config.single_thread_udp is true.  */
+  pthread_t thread_udp_single;
+
+  struct resolv_redirect_config config;
+  bool termination_requested;
+};
+
+/* Function implementing a server thread.  */
+typedef void (*thread_callback) (struct resolv_test *, int server_index);
+
+/* Storage for thread-specific data, for passing to the
+   thread_callback function.  */
+struct thread_closure
+{
+  struct resolv_test *obj;      /* Current test object.  */
+  thread_callback callback;     /* Function to call.  */
+  int server_index;             /* Index of the implemented server.  */
+};
+
+/* Wrap response_callback as a function which can be passed to
+   pthread_create.  */
+static void *
+thread_callback_wrapper (void *arg)
+{
+  struct thread_closure *closure = arg;
+  closure->callback (closure->obj, closure->server_index);
+  free (closure);
+  return NULL;
+}
+
+/* Start a server thread for the specified SERVER_INDEX, implemented
+   by CALLBACK.  */
+static pthread_t
+start_server_thread (struct resolv_test *obj, int server_index,
+                     thread_callback callback)
+{
+  struct thread_closure *closure = xmalloc (sizeof (*closure));
+  *closure = (struct thread_closure)
+    {
+      .obj = obj,
+      .callback = callback,
+      .server_index = server_index,
+    };
+  return xpthread_create (NULL, thread_callback_wrapper, closure);
+}
+
+/* Process one UDP query.  Return false if a termination requested has
+   been detected.  */
+static bool
+server_thread_udp_process_one (struct resolv_test *obj, int server_index)
+{
+  unsigned char query[512];
+  struct sockaddr_storage peer;
+  socklen_t peerlen = sizeof (peer);
+  size_t length = xrecvfrom (obj->servers[server_index].socket_udp,
+                             query, sizeof (query), 0,
+                             (struct sockaddr *) &peer, &peerlen);
+  /* Check for termination.  */
+  {
+    bool termination_requested;
+    xpthread_mutex_lock (&obj->lock);
+    termination_requested = obj->termination_requested;
+    xpthread_mutex_unlock (&obj->lock);
+    if (termination_requested)
+      return false;
+  }
+
+
+  struct query_info qinfo;
+  parse_query (&qinfo, query, length);
+  if (test_verbose > 0)
+    {
+      if (test_verbose > 1)
+        printf ("info: UDP server %d: incoming query:"
+                " %zd bytes, %s/%u/%u, tnxid=0x%02x%02x\n",
+                server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype,
+                query[0], query[1]);
+      else
+        printf ("info: UDP server %d: incoming query:"
+                " %zd bytes, %s/%u/%u\n",
+                server_index, length, qinfo.qname, qinfo.qclass, qinfo.qtype);
+    }
+
+  struct resolv_response_context ctx =
+    {
+      .query_buffer = query,
+      .query_length = length,
+      .server_index = server_index,
+      .tcp = false,
+      .edns = qinfo.edns,
+    };
+  struct resolv_response_builder *b = response_builder_allocate (query, length);
+  obj->config.response_callback
+    (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype);
+
+  if (b->drop)
+    {
+      if (test_verbose)
+        printf ("info: UDP server %d: dropping response to %s/%u/%u\n",
+                server_index, qinfo.qname, qinfo.qclass, qinfo.qtype);
+    }
+  else
+    {
+      if (test_verbose)
+        {
+          if (b->offset >= 12)
+            printf ("info: UDP server %d: sending response:"
+                    " %zu bytes, RCODE %d (for %s/%u/%u)\n",
+                    server_index, b->offset, b->buffer[3] & 0x0f,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype);
+          else
+            printf ("info: UDP server %d: sending response: %zu bytes"
+                    " (for %s/%u/%u)\n",
+                    server_index, b->offset,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype);
+          if (b->truncate_bytes > 0)
+            printf ("info:    truncated by %u bytes\n", b->truncate_bytes);
+        }
+      size_t to_send = b->offset;
+      if (to_send < b->truncate_bytes)
+        to_send = 0;
+      else
+        to_send -= b->truncate_bytes;
+
+      /* Ignore most errors here because the other end may have closed
+         the socket. */
+      if (sendto (obj->servers[server_index].socket_udp,
+                  b->buffer, to_send, 0,
+                  (struct sockaddr *) &peer, peerlen) < 0)
+        TEST_VERIFY_EXIT (errno != EBADF);
+    }
+  response_builder_free (b);
+  return true;
+}
+
+/* UDP thread_callback function.  Variant for one thread per
+   server.  */
+static void
+server_thread_udp (struct resolv_test *obj, int server_index)
+{
+  while (server_thread_udp_process_one (obj, server_index))
+    ;
+}
+
+/* Single-threaded UDP processing function, for the single_thread_udp
+   case.  */
+static void *
+server_thread_udp_single (void *closure)
+{
+  struct resolv_test *obj = closure;
+
+  struct pollfd fds[resolv_max_test_servers];
+  for (int server_index = 0; server_index < resolv_max_test_servers;
+       ++server_index)
+    if (obj->config.servers[server_index].disable_udp)
+      fds[server_index] = (struct pollfd) {.fd = -1};
+    else
+      {
+        fds[server_index] = (struct pollfd)
+          {
+            .fd = obj->servers[server_index].socket_udp,
+            .events = POLLIN
+          };
+
+        /* Make the socket non-blocking.  */
+        int flags = fcntl (obj->servers[server_index].socket_udp, F_GETFL, 0);
+        if (flags < 0)
+          FAIL_EXIT1 ("fcntl (F_GETFL): %m");
+        flags |= O_NONBLOCK;
+        if (fcntl (obj->servers[server_index].socket_udp, F_SETFL, flags) < 0)
+          FAIL_EXIT1 ("fcntl (F_SETFL): %m");
+      }
+
+  while (true)
+    {
+      xpoll (fds, resolv_max_test_servers, -1);
+      for (int server_index = 0; server_index < resolv_max_test_servers;
+           ++server_index)
+        if (fds[server_index].revents != 0)
+          {
+            if (!server_thread_udp_process_one (obj, server_index))
+              goto out;
+            fds[server_index].revents = 0;
+          }
+    }
+
+ out:
+  return NULL;
+}
+
+/* Start the single UDP handler thread (for the single_thread_udp
+   case).  */
+static void
+start_server_thread_udp_single (struct resolv_test *obj)
+{
+  obj->thread_udp_single
+    = xpthread_create (NULL, server_thread_udp_single, obj);
+}
+
+/* Data describing a TCP client connect.  */
+struct tcp_thread_closure
+{
+  struct resolv_test *obj;
+  int server_index;
+  int client_socket;
+};
+
+/* Read a complete DNS query packet.  If EOF_OK, an immediate
+   end-of-file condition is acceptable.  */
+static bool
+read_fully (int fd, void *buf, size_t len, bool eof_ok)
+{
+  const void *const end = buf + len;
+  while (buf < end)
+    {
+      ssize_t ret = read (fd, buf, end - buf);
+      if (ret == 0)
+        {
+          if (!eof_ok)
+            {
+              support_record_failure ();
+              printf ("error: unexpected EOF on TCP connection\n");
+            }
+          return false;
+        }
+      else if (ret < 0)
+        {
+          if (!eof_ok || errno != ECONNRESET)
+            {
+              support_record_failure ();
+              printf ("error: TCP read: %m\n");
+            }
+          return false;
+        }
+      buf += ret;
+      eof_ok = false;
+    }
+  return true;
+}
+
+/* Write an array of iovecs.  Terminate the process on failure.  */
+static void
+writev_fully (int fd, struct iovec *buffers, size_t count)
+{
+  while (count > 0)
+    {
+      /* Skip zero-length write requests.  */
+      if (buffers->iov_len == 0)
+        {
+          ++buffers;
+          --count;
+          continue;
+        }
+      /* Try to rewrite the remaing buffers.  */
+      ssize_t ret = writev (fd, buffers, count);
+      if (ret < 0)
+        FAIL_EXIT1 ("writev: %m");
+      if (ret == 0)
+        FAIL_EXIT1 ("writev: invalid return value zero");
+      /* Find the buffers that were successfully written.  */
+      while (ret > 0)
+        {
+          if (count == 0)
+            FAIL_EXIT1 ("internal writev consistency failure");
+          /* Current buffer was partially written.  */
+          if (buffers->iov_len > (size_t) ret)
+            {
+              buffers->iov_base += ret;
+              buffers->iov_len -= ret;
+              ret = 0;
+            }
+          else
+            {
+              ret -= buffers->iov_len;
+              buffers->iov_len = 0;
+              ++buffers;
+              --count;
+            }
+        }
+    }
+}
+
+/* Thread callback for handling a single established TCP connection to
+   a client.  */
+static void *
+server_thread_tcp_client (void *arg)
+{
+  struct tcp_thread_closure *closure = arg;
+
+  while (true)
+    {
+      /* Read packet length.  */
+      uint16_t query_length;
+      if (!read_fully (closure->client_socket,
+                       &query_length, sizeof (query_length), true))
+        break;
+      query_length = ntohs (query_length);
+
+      /* Read the packet.  */
+      unsigned char *query_buffer = xmalloc (query_length);
+      read_fully (closure->client_socket, query_buffer, query_length, false);
+
+      struct query_info qinfo;
+      parse_query (&qinfo, query_buffer, query_length);
+      if (test_verbose > 0)
+        {
+          if (test_verbose > 1)
+            printf ("info: UDP server %d: incoming query:"
+                    " %d bytes, %s/%u/%u, tnxid=0x%02x%02x\n",
+                    closure->server_index, query_length,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype,
+                    query_buffer[0], query_buffer[1]);
+          else
+            printf ("info: TCP server %d: incoming query:"
+                    " %u bytes, %s/%u/%u\n",
+                    closure->server_index, query_length,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype);
+        }
+
+      struct resolv_response_context ctx =
+        {
+          .query_buffer = query_buffer,
+          .query_length = query_length,
+          .server_index = closure->server_index,
+          .tcp = true,
+          .edns = qinfo.edns,
+        };
+      struct resolv_response_builder *b = response_builder_allocate
+        (query_buffer, query_length);
+      closure->obj->config.response_callback
+        (&ctx, b, qinfo.qname, qinfo.qclass, qinfo.qtype);
+
+      if (b->drop)
+        {
+          if (test_verbose)
+            printf ("info: TCP server %d: dropping response to %s/%u/%u\n",
+                    closure->server_index,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype);
+        }
+      else
+        {
+          if (test_verbose)
+            printf ("info: TCP server %d: sending response: %zu bytes"
+                    " (for %s/%u/%u)\n",
+                    closure->server_index, b->offset,
+                    qinfo.qname, qinfo.qclass, qinfo.qtype);
+          uint16_t length = htons (b->offset);
+          size_t to_send = b->offset;
+          if (to_send < b->truncate_bytes)
+            to_send = 0;
+          else
+            to_send -= b->truncate_bytes;
+          struct iovec buffers[2] =
+            {
+              {&length, sizeof (length)},
+              {b->buffer, to_send}
+            };
+          writev_fully (closure->client_socket, buffers, 2);
+        }
+      bool close_flag = b->close;
+      response_builder_free (b);
+      free (query_buffer);
+      if (close_flag)
+        break;
+    }
+
+  xclose (closure->client_socket);
+  free (closure);
+  return NULL;
+}
+
+/* thread_callback for the TCP case.  Accept connections and create a
+   new thread for each client.  */
+static void
+server_thread_tcp (struct resolv_test *obj, int server_index)
+{
+  while (true)
+    {
+      /* Get the client conenction.  */
+      int client_socket = xaccept
+        (obj->servers[server_index].socket_tcp, NULL, NULL);
+
+      /* Check for termination.  */
+      xpthread_mutex_lock (&obj->lock);
+      if (obj->termination_requested)
+        {
+          xpthread_mutex_unlock (&obj->lock);
+          xclose (client_socket);
+          break;
+        }
+      xpthread_mutex_unlock (&obj->lock);
+
+      /* Spawn a new thread for handling this connection.  */
+      struct tcp_thread_closure *closure = xmalloc (sizeof (*closure));
+      *closure = (struct tcp_thread_closure)
+        {
+          .obj = obj,
+          .server_index = server_index,
+          .client_socket = client_socket,
+        };
+
+      pthread_t thr
+        = xpthread_create (NULL, server_thread_tcp_client, closure);
+      /* TODO: We should keep track of this thread so that we can
+         block in resolv_test_end until it has exited.  */
+      xpthread_detach (thr);
+    }
+}
+
+/* Create UDP and TCP server sockets.  */
+static void
+make_server_sockets (struct resolv_test_server *server)
+{
+  while (true)
+    {
+      server->socket_udp = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+      server->socket_tcp = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
+
+      /* Pick the address for the UDP socket.  */
+      server->address = (struct sockaddr_in)
+        {
+          .sin_family = AF_INET,
+          .sin_addr = {.s_addr = htonl (INADDR_LOOPBACK)}
+        };
+      xbind (server->socket_udp,
+             (struct sockaddr *)&server->address, sizeof (server->address));
+
+      /* Retrieve the address. */
+      socklen_t addrlen = sizeof (server->address);
+      xgetsockname (server->socket_udp,
+                    (struct sockaddr *)&server->address, &addrlen);
+
+      /* Bind the TCP socket to the same address.  */
+      {
+        int on = 1;
+        xsetsockopt (server->socket_tcp, SOL_SOCKET, SO_REUSEADDR,
+                     &on, sizeof (on));
+      }
+      if (bind (server->socket_tcp,
+                (struct sockaddr *)&server->address,
+                sizeof (server->address)) != 0)
+        {
+          /* Port collision.  The UDP bind succeeded, but the TCP BIND
+             failed.  We assume here that the kernel will pick the
+             next local UDP address randomly.  */
+          if (errno == EADDRINUSE)
+            {
+              xclose (server->socket_udp);
+              xclose (server->socket_tcp);
+              continue;
+            }
+          FAIL_EXIT1 ("TCP bind: %m");
+        }
+      xlisten (server->socket_tcp, 5);
+      break;
+    }
+}
+
+/* One-time initialization of NSS.  */
+static void
+resolv_redirect_once (void)
+{
+  /* Only use nss_dns.  */
+  __nss_configure_lookup ("hosts", "dns");
+  __nss_configure_lookup ("networks", "dns");
+  /* Enter a network namespace for isolation and firewall state
+     cleanup.  The tests will still work if these steps fail, but they
+     may be less reliable.  */
+  support_become_root ();
+  support_enter_network_namespace ();
+}
+pthread_once_t resolv_redirect_once_var = PTHREAD_ONCE_INIT;
+
+void
+resolv_test_init (void)
+{
+  /* Perform one-time initialization of NSS.  */
+  xpthread_once (&resolv_redirect_once_var, resolv_redirect_once);
+}
+
+/* Copy the search path from CONFIG.search to the _res object.  */
+static void
+set_search_path (struct resolv_redirect_config config)
+{
+  memset (_res.defdname, 0, sizeof (_res.defdname));
+  memset (_res.dnsrch, 0, sizeof (_res.dnsrch));
+
+  char *current = _res.defdname;
+  char *end = current + sizeof (_res.defdname);
+
+  for (unsigned int i = 0;
+       i < sizeof (config.search) / sizeof (config.search[0]); ++i)
+    {
+      if (config.search[i] == NULL)
+        continue;
+
+      size_t length = strlen (config.search[i]) + 1;
+      size_t remaining = end - current;
+      TEST_VERIFY_EXIT (length <= remaining);
+      memcpy (current, config.search[i], length);
+      _res.dnsrch[i] = current;
+      current += length;
+    }
+}
+
+struct resolv_test *
+resolv_test_start (struct resolv_redirect_config config)
+{
+  /* Apply configuration defaults.  */
+  if (config.nscount == 0)
+    config.nscount = resolv_max_test_servers;
+
+  struct resolv_test *obj = xmalloc (sizeof (*obj));
+  *obj = (struct resolv_test) {
+    .config = config,
+    .lock = PTHREAD_MUTEX_INITIALIZER,
+  };
+
+  resolv_test_init ();
+
+  /* Create all the servers, to reserve the necessary ports.  */
+  for (int server_index = 0; server_index < config.nscount; ++server_index)
+    make_server_sockets (obj->servers + server_index);
+
+  /* Start server threads.  Disable the server ports, as
+     requested.  */
+  for (int server_index = 0; server_index < config.nscount; ++server_index)
+    {
+      struct resolv_test_server *server = obj->servers + server_index;
+      if (config.servers[server_index].disable_udp)
+        {
+          xclose (server->socket_udp);
+          server->socket_udp = -1;
+        }
+      else if (!config.single_thread_udp)
+        server->thread_udp = start_server_thread (obj, server_index,
+                                                  server_thread_udp);
+      if (config.servers[server_index].disable_tcp)
+        {
+          xclose (server->socket_tcp);
+          server->socket_tcp = -1;
+        }
+      else
+        server->thread_tcp = start_server_thread (obj, server_index,
+                                                  server_thread_tcp);
+    }
+  if (config.single_thread_udp)
+    start_server_thread_udp_single (obj);
+
+  int timeout = 1;
+
+  /* Initialize libresolv.  */
+  TEST_VERIFY_EXIT (res_init () == 0);
+
+  /* Disable IPv6 name server addresses.  The code below only
+     overrides the IPv4 addresses.  */
+  __res_iclose (&_res, true);
+  _res._u._ext.nscount = 0;
+
+  /* Redirect queries to the server socket.  */
+  if (test_verbose)
+    {
+      printf ("info: old timeout value: %d\n", _res.retrans);
+      printf ("info: old retry attempt value: %d\n", _res.retry);
+      printf ("info: old _res.options: 0x%lx\n", _res.options);
+      printf ("info: old _res.nscount value: %d\n", _res.nscount);
+      printf ("info: old _res.ndots value: %d\n", _res.ndots);
+    }
+  _res.retrans = timeout;
+  _res.retry = 4;
+  _res.nscount = config.nscount;
+  _res.options = RES_INIT | RES_RECURSE | RES_DEFNAMES | RES_DNSRCH;
+  _res.ndots = 1;
+  if (test_verbose)
+    {
+      printf ("info: new timeout value: %d\n", _res.retrans);
+      printf ("info: new retry attempt value: %d\n", _res.retry);
+      printf ("info: new _res.options: 0x%lx\n", _res.options);
+      printf ("info: new _res.nscount value: %d\n", _res.nscount);
+      printf ("info: new _res.ndots value: %d\n", _res.ndots);
+    }
+  for (int server_index = 0; server_index < config.nscount; ++server_index)
+    {
+      _res.nsaddr_list[server_index] = obj->servers[server_index].address;
+      if (test_verbose)
+        {
+          char buf[256];
+          TEST_VERIFY_EXIT
+            (inet_ntop (AF_INET, &obj->servers[server_index].address.sin_addr,
+                        buf, sizeof (buf)) != NULL);
+          printf ("info: server %d: %s/%u\n",
+                  server_index, buf,
+                  htons (obj->servers[server_index].address.sin_port));
+        }
+    }
+
+  set_search_path (config);
+
+  return obj;
+}
+
+void
+resolv_test_end (struct resolv_test *obj)
+{
+  res_close ();
+
+  xpthread_mutex_lock (&obj->lock);
+  obj->termination_requested = true;
+  xpthread_mutex_unlock (&obj->lock);
+
+  /* Send trigger packets to unblock the server threads.  */
+  for (int server_index = 0; server_index < obj->config.nscount;
+       ++server_index)
+    {
+      if (!obj->config.servers[server_index].disable_udp)
+        {
+          int sock = xsocket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
+          xsendto (sock, "", 1, 0,
+                   (struct sockaddr *) &obj->servers[server_index].address,
+                   sizeof (obj->servers[server_index].address));
+          xclose (sock);
+        }
+      if (!obj->config.servers[server_index].disable_tcp)
+        {
+          int sock = xsocket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
+          xconnect (sock,
+                    (struct sockaddr *) &obj->servers[server_index].address,
+                    sizeof (obj->servers[server_index].address));
+          xclose (sock);
+        }
+    }
+
+  if (obj->config.single_thread_udp)
+    xpthread_join (obj->thread_udp_single);
+
+  /* Wait for the server threads to terminate.  */
+  for (int server_index = 0; server_index < obj->config.nscount;
+       ++server_index)
+    {
+      if (!obj->config.servers[server_index].disable_udp)
+        {
+          if (!obj->config.single_thread_udp)
+            xpthread_join (obj->servers[server_index].thread_udp);
+          xclose (obj->servers[server_index].socket_udp);
+        }
+      if (!obj->config.servers[server_index].disable_tcp)
+        {
+          xpthread_join (obj->servers[server_index].thread_tcp);
+          xclose (obj->servers[server_index].socket_tcp);
+        }
+    }
+
+  free (obj);
+}
diff --git a/support/resolv_test.h b/support/resolv_test.h
new file mode 100644
index 0000000..6498751
--- /dev/null
+++ b/support/resolv_test.h
@@ -0,0 +1,180 @@
+/* DNS test framework and libresolv redirection.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_RESOLV_TEST_H
+#define SUPPORT_RESOLV_TEST_H
+
+#include <arpa/nameser.h>
+#include <stdbool.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Information about EDNS properties of a DNS query.  */
+struct resolv_edns_info
+{
+  bool active;
+  uint8_t extended_rcode;
+  uint8_t version;
+  uint16_t flags;
+  uint16_t payload_size;
+};
+
+/* This struct provides context information when the response callback
+   specified in struct resolv_redirect_config is invoked. */
+struct resolv_response_context
+{
+  const unsigned char *query_buffer;
+  size_t query_length;
+  int server_index;
+  bool tcp;
+  struct resolv_edns_info edns;
+};
+
+/* This opaque struct is used to construct responses from within the
+   response callback function.  */
+struct resolv_response_builder;
+
+/* This opaque struct collects information about the resolver testing
+   currently in progress.  */
+struct resolv_test;
+
+enum
+  {
+    /* Maximum number of test servers supported by the framework.  */
+    resolv_max_test_servers = 3,
+  };
+
+/* Configuration settings specific to individual test servers.  */
+struct resolv_redirect_server_config
+{
+  bool disable_tcp;             /* If true, no TCP server is listening.  */
+  bool disable_udp;             /* If true, no UDP server is listening.  */
+};
+
+/* Instructions for setting up the libresolv redirection.  */
+struct resolv_redirect_config
+{
+  /* The response_callback function is called for every incoming DNS
+     packet, over UDP or TCP.  It must be specified, the other
+     configuration settings are optional.  */
+  void (*response_callback) (const struct resolv_response_context *,
+                             struct resolv_response_builder *,
+                             const char *qname,
+                             uint16_t qclass, uint16_t qtype);
+
+  /* Per-server configuration.  */
+  struct resolv_redirect_server_config servers[resolv_max_test_servers];
+
+  /* Search path entries.  The first entry serves as the default
+     domain name as well.  */
+  const char *search[7];
+
+  /* Number of servers to activate in resolv.  0 means the default,
+     resolv_max_test_servers.  */
+  int nscount;
+
+  /* If true, use a single thread to process all UDP queries.  This
+     may results in more predictable ordering of queries and
+     responses.  */
+  bool single_thread_udp;
+};
+
+/* Configure NSS to use, nss_dns only for aplicable databases, and try
+   to put the process into a network namespace for better isolation.
+   This may have to be called before resolv_test_start, before the
+   process creates any threads.  Otherwise, initialization is
+   performed by resolv_test_start implicitly.  */
+void resolv_test_init (void);
+
+/* Initiate resolver testing.  This updates the _res variable as
+   needed.  As a side effect, NSS is reconfigured to use nss_dns only
+   for aplicable databases, and the process may enter a network
+   namespace for better isolation.  */
+struct resolv_test *resolv_test_start (struct resolv_redirect_config);
+
+/* Call this function at the end of resolver testing, to free
+   resources and report pending errors (if any).  */
+void resolv_test_end (struct resolv_test *);
+
+/* The remaining facilities in this file are used for constructing
+   response packets from the response_callback function.  */
+
+/* Special settings for constructing responses from the callback.  */
+struct resolv_response_flags
+{
+  /* 4-bit response code to incorporate into the response. */
+  unsigned char rcode;
+
+  /* If true, the TC (truncation) flag will be set.  */
+  bool tc;
+
+  /* Initial section count values.  Can be used to artificially
+     increase the counts, for malformed packet testing.*/
+  unsigned short qdcount;
+  unsigned short ancount;
+  unsigned short nscount;
+  unsigned short adcount;
+};
+
+/* Begin a new response with the requested flags.  Must be called
+   first.  */
+void resolv_response_init (struct resolv_response_builder *,
+                           struct resolv_response_flags);
+
+/* Switches to the section in the response packet.  Only forward
+   movement is supported.  */
+void resolv_response_section (struct resolv_response_builder *, ns_sect);
+
+/* Add a question record to the question section.  */
+void resolv_response_add_question (struct resolv_response_builder *,
+                                   const char *name, uint16_t class,
+                                   uint16_t type);
+/* Starts a new resource record with the specified owner name, class,
+   type, and TTL.  Data is supplied with resolv_response_add_data or
+   resolv_response_add_name.  */
+void resolv_response_open_record (struct resolv_response_builder *,
+                                  const char *name, uint16_t class,
+                                  uint16_t type, uint32_t ttl);
+
+/* Add unstructed bytes to the RDATA part of a resource record.  */
+void resolv_response_add_data (struct resolv_response_builder *,
+                               const void *, size_t);
+
+/* Add a compressed domain name to the RDATA part of a resource
+   record.  */
+void resolv_response_add_name (struct resolv_response_builder *,
+                               const char *name);
+
+/* Mark the end of the constructed record.  Must be called last.  */
+void resolv_response_close_record (struct resolv_response_builder *);
+
+/* Drop this query packet (that is, do not send a response, not even
+   an empty packet).  */
+void resolv_response_drop (struct resolv_response_builder *);
+
+/* In TCP mode, close the connection after this packet (if a response
+   is sent).  */
+void resolv_response_close (struct resolv_response_builder *);
+
+/* The size of the response packet built so far.  */
+size_t resolv_response_length (const struct resolv_response_builder *);
+
+__END_DECLS
+
+#endif /* SUPPORT_RESOLV_TEST_H */
diff --git a/support/run_diff.h b/support/run_diff.h
new file mode 100644
index 0000000..f65b5dd
--- /dev/null
+++ b/support/run_diff.h
@@ -0,0 +1,31 @@
+/* Invoke the system diff tool to compare two strings.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_RUN_DIFF_H
+#define SUPPORT_RUN_DIFF_H
+
+/* Compare the two NUL-terminated strings LEFT and RIGHT using the
+   diff tool.  Label the sides of the diff with LEFT_LABEL and
+   RIGHT_LABEL, respectively.
+
+   This function assumes that LEFT and RIGHT are different
+   strings.  */
+void support_run_diff (const char *left_label, const char *left,
+                       const char *right_label, const char *right);
+
+#endif /* SUPPORT_RUN_DIFF_H */
diff --git a/support/set_fortify_handler.c b/support/set_fortify_handler.c
new file mode 100644
index 0000000..f434a80
--- /dev/null
+++ b/support/set_fortify_handler.c
@@ -0,0 +1,34 @@
+/* Set signal handler for use in fortify tests.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <signal.h>
+
+void
+set_fortify_handler (void (*handler) (int sig))
+{
+  struct sigaction sa;
+
+  sa.sa_handler = handler;
+  sa.sa_flags = 0;
+  sigemptyset (&sa.sa_mask);
+
+  sigaction (SIGABRT, &sa, NULL);
+  ignore_stderr ();
+}
diff --git a/support/support-xstat.c b/support/support-xstat.c
new file mode 100644
index 0000000..86a81ec
--- /dev/null
+++ b/support/support-xstat.c
@@ -0,0 +1,30 @@
+/* stat64 with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* NB: Non-standard file name to avoid sysdeps override for xstat.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/stat.h>
+
+void
+xstat (const char *path, struct stat64 *result)
+{
+  if (stat64 (path, result) != 0)
+    FAIL_EXIT1 ("stat64 (\"%s\"): %m", path);
+}
diff --git a/support/support.h b/support/support.h
new file mode 100644
index 0000000..4b5f04c
--- /dev/null
+++ b/support/support.h
@@ -0,0 +1,74 @@
+/* Common extra functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This header file should only contain definitions compatible with
+   C90.  (Using __attribute__ is fine because <features.h> provides a
+   fallback.)  */
+
+#ifndef SUPPORT_H
+#define SUPPORT_H
+
+#include <stddef.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Write a message to standard output.  Can be used in signal
+   handlers.  */
+void write_message (const char *message) __attribute__ ((nonnull (1)));
+
+/* Avoid all the buffer overflow messages on stderr.  */
+void ignore_stderr (void);
+
+/* Set fortification error handler.  Used when tests want to verify that bad
+   code is caught by the library.  */
+void set_fortify_handler (void (*handler) (int sig));
+
+/* Report an out-of-memory error for the allocation of SIZE bytes in
+   FUNCTION, terminating the process.  */
+void oom_error (const char *function, size_t size)
+  __attribute__ ((nonnull (1)));
+
+/* Return a pointer to a memory region of SIZE bytes.  The memory is
+   initialized to zero and will be shared with subprocesses (across
+   fork).  The returned pointer must be freed using
+   support_shared_free; it is not compatible with the malloc
+   functions.  */
+void *support_shared_allocate (size_t size);
+
+/* Deallocate a pointer returned by support_shared_allocate.  */
+void support_shared_free (void *);
+
+/* Write CONTENTS to the file PATH.  Create or truncate the file as
+   needed.  The file mode is 0666 masked by the umask.  Terminate the
+   process on error.  */
+void support_write_file_string (const char *path, const char *contents);
+
+/* Error-checking wrapper functions which terminate the process on
+   error.  */
+
+void *xmalloc (size_t) __attribute__ ((malloc));
+void *xcalloc (size_t n, size_t s) __attribute__ ((malloc));
+void *xrealloc (void *p, size_t n);
+char *xasprintf (const char *format, ...)
+  __attribute__ ((format (printf, 1, 2), malloc));
+char *xstrdup (const char *);
+
+__END_DECLS
+
+#endif /* SUPPORT_H */
diff --git a/support/support_become_root.c b/support/support_become_root.c
new file mode 100644
index 0000000..3fa0bd4
--- /dev/null
+++ b/support/support_become_root.c
@@ -0,0 +1,40 @@
+/* Acquire root privileges.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/namespace.h>
+
+#include <sched.h>
+#include <stdio.h>
+#include <unistd.h>
+
+bool
+support_become_root (void)
+{
+#ifdef CLONE_NEWUSER
+  if (unshare (CLONE_NEWUSER | CLONE_NEWNS) == 0)
+    /* Even if we do not have UID zero, we have extended privileges at
+       this point.  */
+    return true;
+#endif
+  if (setuid (0) != 0)
+    {
+      printf ("warning: could not become root outside namespace (%m)\n");
+      return false;
+    }
+  return true;
+}
diff --git a/support/support_can_chroot.c b/support/support_can_chroot.c
new file mode 100644
index 0000000..0dfd2de
--- /dev/null
+++ b/support/support_can_chroot.c
@@ -0,0 +1,65 @@
+/* Return true if the process can perform a chroot operation.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdio.h>
+#include <support/check.h>
+#include <support/namespace.h>
+#include <support/support.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <xunistd.h>
+
+static void
+callback (void *closure)
+{
+  int *result = closure;
+  struct stat64 before;
+  xstat ("/dev", &before);
+  if (chroot ("/dev") != 0)
+    {
+      *result = errno;
+      return;
+    }
+  struct stat64 after;
+  xstat ("/", &after);
+  TEST_VERIFY (before.st_dev == after.st_dev);
+  TEST_VERIFY (before.st_ino == after.st_ino);
+  *result = 0;
+}
+
+bool
+support_can_chroot (void)
+{
+  int *result = support_shared_allocate (sizeof (*result));
+  *result = 0;
+  support_isolate_in_subprocess (callback, result);
+  bool ok = *result == 0;
+  if (!ok)
+    {
+      static bool already_warned;
+      if (!already_warned)
+        {
+          already_warned = true;
+          errno = *result;
+          printf ("warning: this process does not support chroot: %m\n");
+        }
+    }
+  support_shared_free (result);
+  return ok;
+}
diff --git a/support/support_capture_subprocess.c b/support/support_capture_subprocess.c
new file mode 100644
index 0000000..030f124
--- /dev/null
+++ b/support/support_capture_subprocess.c
@@ -0,0 +1,108 @@
+/* Capture output from a subprocess.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/capture_subprocess.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <support/xsocket.h>
+
+static void
+transfer (const char *what, struct pollfd *pfd, struct xmemstream *stream)
+{
+  if (pfd->revents != 0)
+    {
+      char buf[1024];
+      ssize_t ret = TEMP_FAILURE_RETRY (read (pfd->fd, buf, sizeof (buf)));
+      if (ret < 0)
+        {
+          support_record_failure ();
+          printf ("error: reading from subprocess %s: %m", what);
+          pfd->events = 0;
+          pfd->revents = 0;
+        }
+      else if (ret == 0)
+        {
+          /* EOF reached.  Stop listening.  */
+          pfd->events = 0;
+          pfd->revents = 0;
+        }
+      else
+        /* Store the data just read.   */
+        TEST_VERIFY (fwrite (buf, ret, 1, stream->out) == 1);
+    }
+}
+
+struct support_capture_subprocess
+support_capture_subprocess (void (*callback) (void *), void *closure)
+{
+  struct support_capture_subprocess result;
+  xopen_memstream (&result.out);
+  xopen_memstream (&result.err);
+
+  int stdout_pipe[2];
+  xpipe (stdout_pipe);
+  int stderr_pipe[2];
+  xpipe (stderr_pipe);
+
+  TEST_VERIFY (fflush (stdout) == 0);
+  TEST_VERIFY (fflush (stderr) == 0);
+
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      xclose (stdout_pipe[0]);
+      xclose (stderr_pipe[0]);
+      xdup2 (stdout_pipe[1], STDOUT_FILENO);
+      xdup2 (stderr_pipe[1], STDERR_FILENO);
+      callback (closure);
+      _exit (0);
+    }
+  xclose (stdout_pipe[1]);
+  xclose (stderr_pipe[1]);
+
+  struct pollfd fds[2] =
+    {
+      { .fd = stdout_pipe[0], .events = POLLIN },
+      { .fd = stderr_pipe[0], .events = POLLIN },
+    };
+
+  do
+    {
+      xpoll (fds, 2, -1);
+      transfer ("stdout", &fds[0], &result.out);
+      transfer ("stderr", &fds[1], &result.err);
+    }
+  while (fds[0].events != 0 || fds[1].events != 0);
+  xclose (stdout_pipe[0]);
+  xclose (stderr_pipe[0]);
+
+  xfclose_memstream (&result.out);
+  xfclose_memstream (&result.err);
+  xwaitpid (pid, &result.status, 0);
+  return result;
+}
+
+void
+support_capture_subprocess_free (struct support_capture_subprocess *p)
+{
+  free (p->out.buffer);
+  free (p->err.buffer);
+}
diff --git a/support/support_capture_subprocess_check.c b/support/support_capture_subprocess_check.c
new file mode 100644
index 0000000..708c89f
--- /dev/null
+++ b/support/support_capture_subprocess_check.c
@@ -0,0 +1,67 @@
+/* Verify capture output from a subprocess.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+
+static void
+print_context (const char *context, bool *failed)
+{
+  if (*failed)
+    /* Do not duplicate message.  */
+    return;
+  support_record_failure ();
+  printf ("error: subprocess failed: %s\n", context);
+}
+
+void
+support_capture_subprocess_check (struct support_capture_subprocess *proc,
+                                  const char *context, int status,
+                                  int allowed)
+{
+  TEST_VERIFY ((allowed & sc_allow_none)
+               || (allowed & sc_allow_stdout)
+               || (allowed & sc_allow_stderr));
+  TEST_VERIFY (!((allowed & sc_allow_none)
+                 && ((allowed & sc_allow_stdout)
+                     || (allowed & sc_allow_stderr))));
+
+  bool failed = false;
+  if (proc->status != status)
+    {
+      print_context (context, &failed);
+      printf ("error:   expected exit status: %d\n", status);
+      printf ("error:   actual exit status:   %d\n", status);
+    }
+  if (!(allowed & sc_allow_stdout) && proc->out.length != 0)
+    {
+      print_context (context, &failed);
+      printf ("error:   unexpected output from subprocess\n");
+      fwrite (proc->out.buffer, proc->out.length, 1, stdout);
+      puts ("\n");
+    }
+  if (!(allowed & sc_allow_stderr) && proc->err.length != 0)
+    {
+      print_context (context, &failed);
+      printf ("error:   unexpected error output from subprocess\n");
+      fwrite (proc->err.buffer, proc->err.length, 1, stdout);
+      puts ("\n");
+    }
+}
diff --git a/support/support_enter_network_namespace.c b/support/support_enter_network_namespace.c
new file mode 100644
index 0000000..28b0ee2
--- /dev/null
+++ b/support/support_enter_network_namespace.c
@@ -0,0 +1,75 @@
+/* Enter a network namespace.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/namespace.h>
+
+#include <net/if.h>
+#include <sched.h>
+#include <stdio.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/xsocket.h>
+#include <support/xunistd.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+static bool in_uts_namespace;
+
+bool
+support_enter_network_namespace (void)
+{
+#ifdef CLONE_NEWUTS
+  if (unshare (CLONE_NEWUTS) == 0)
+    in_uts_namespace = true;
+  else
+    printf ("warning: unshare (CLONE_NEWUTS) failed: %m\n");
+#endif
+
+#ifdef CLONE_NEWNET
+  if (unshare (CLONE_NEWNET) == 0)
+    {
+      /* Bring up the loopback interface.  */
+      int fd = xsocket (AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
+      struct ifreq req;
+      strcpy (req.ifr_name, "lo");
+      TEST_VERIFY_EXIT (ioctl (fd, SIOCGIFFLAGS, &req) == 0);
+      bool already_up = req.ifr_flags & IFF_UP;
+      if (already_up)
+        /* This means that we likely have not achieved isolation from
+           the parent namespace.  */
+        printf ("warning: loopback interface already exists"
+                " in new network namespace\n");
+      else
+        {
+          req.ifr_flags |= IFF_UP | IFF_RUNNING;
+          TEST_VERIFY_EXIT (ioctl (fd, SIOCSIFFLAGS, &req) == 0);
+        }
+      xclose (fd);
+
+      return !already_up;
+    }
+#endif
+  printf ("warning: could not enter network namespace\n");
+  return false;
+}
+
+bool
+support_in_uts_namespace (void)
+{
+  return in_uts_namespace;
+}
diff --git a/support/support_format_address_family.c b/support/support_format_address_family.c
new file mode 100644
index 0000000..5d42c42
--- /dev/null
+++ b/support/support_format_address_family.c
@@ -0,0 +1,35 @@
+/* Convert an address family to a string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <support/support.h>
+
+char *
+support_format_address_family (int family)
+{
+  switch (family)
+    {
+    case AF_INET:
+      return xstrdup ("INET");
+    case AF_INET6:
+      return xstrdup ("INET6");
+    default:
+      return xasprintf ("<unknown address family %d>", family);
+    }
+}
diff --git a/support/support_format_addrinfo.c b/support/support_format_addrinfo.c
new file mode 100644
index 0000000..eedb030
--- /dev/null
+++ b/support/support_format_addrinfo.c
@@ -0,0 +1,239 @@
+/* Convert struct addrinfo values to a string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <stdio.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+static size_t
+socket_address_length (int family)
+{
+  switch (family)
+    {
+    case AF_INET:
+      return sizeof (struct sockaddr_in);
+    case AF_INET6:
+      return sizeof (struct sockaddr_in6);
+    default:
+      return -1;
+    }
+}
+
+static void
+format_ai_flags_1 (FILE *out, struct addrinfo *ai, int flag, const char *name,
+                   int * flags_printed)
+{
+  if ((ai->ai_flags & flag) != 0)
+    fprintf (out, " %s", name);
+  *flags_printed |= flag;
+}
+
+static void
+format_ai_flags (FILE *out, struct addrinfo *ai)
+{
+  if (ai == NULL)
+    return;
+
+  if (ai->ai_flags != 0)
+    {
+      fprintf (out, "flags:");
+      int flags_printed = 0;
+#define FLAG(flag) format_ai_flags_1 (out, ai, flag, #flag, &flags_printed)
+      FLAG (AI_PASSIVE);
+      FLAG (AI_CANONNAME);
+      FLAG (AI_NUMERICHOST);
+      FLAG (AI_V4MAPPED);
+      FLAG (AI_ALL);
+      FLAG (AI_ADDRCONFIG);
+      FLAG (AI_IDN);
+      FLAG (AI_CANONIDN);
+      FLAG (AI_IDN_ALLOW_UNASSIGNED);
+      FLAG (AI_IDN_USE_STD3_ASCII_RULES);
+      FLAG (AI_NUMERICSERV);
+#undef FLAG
+      int remaining = ai->ai_flags & ~flags_printed;
+      if (remaining != 0)
+        fprintf (out, " %08x", remaining);
+      fprintf (out, "\n");
+    }
+
+  /* Report flag mismatches within the list.  */
+  int flags = ai->ai_flags;
+  int index = 1;
+  ai = ai->ai_next;
+  while (ai != NULL)
+    {
+      if (ai->ai_flags != flags)
+        fprintf (out, "error: flags at %d: 0x%x expected, 0x%x actual\n",
+                 index, flags, ai->ai_flags);
+      ai = ai->ai_next;
+      ++index;
+    }
+}
+
+static void
+format_ai_canonname (FILE *out, struct addrinfo *ai)
+{
+  if (ai == NULL)
+    return;
+  if (ai->ai_canonname != NULL)
+    fprintf (out, "canonname: %s\n", ai->ai_canonname);
+
+  /* Report incorrectly set ai_canonname fields on subsequent list
+     entries.  */
+  int index = 1;
+  ai = ai->ai_next;
+  while (ai != NULL)
+    {
+      if (ai->ai_canonname != NULL)
+        fprintf (out, "error: canonname set at %d: %s\n",
+                 index, ai->ai_canonname);
+      ai = ai->ai_next;
+      ++index;
+    }
+}
+
+static void
+format_ai_one (FILE *out, struct addrinfo *ai)
+{
+  {
+    char type_buf[32];
+    const char *type_str;
+    char proto_buf[32];
+    const char *proto_str;
+
+    /* ai_socktype */
+    switch (ai->ai_socktype)
+      {
+      case SOCK_RAW:
+        type_str = "RAW";
+        break;
+      case SOCK_DGRAM:
+        type_str = "DGRAM";
+        break;
+      case SOCK_STREAM:
+        type_str = "STREAM";
+        break;
+      default:
+        snprintf (type_buf, sizeof (type_buf), "%d", ai->ai_socktype);
+        type_str = type_buf;
+      }
+
+    /* ai_protocol */
+    switch (ai->ai_protocol)
+      {
+      case IPPROTO_IP:
+        proto_str = "IP";
+        break;
+      case IPPROTO_UDP:
+        proto_str = "UDP";
+        break;
+      case IPPROTO_TCP:
+        proto_str = "TCP";
+        break;
+      default:
+        snprintf (proto_buf, sizeof (proto_buf), "%d", ai->ai_protocol);
+        proto_str = proto_buf;
+      }
+    fprintf (out, "address: %s/%s", type_str, proto_str);
+  }
+
+  /* ai_addrlen */
+  if (ai->ai_addrlen != socket_address_length (ai->ai_family))
+    {
+      char *family = support_format_address_family (ai->ai_family);
+      fprintf (out, "error: invalid address length %d for %s\n",
+               ai->ai_addrlen, family);
+      free (family);
+    }
+
+  /* ai_addr */
+  {
+    char buf[128];
+    uint16_t port;
+    const char *ret;
+    switch (ai->ai_family)
+      {
+      case AF_INET:
+        {
+          struct sockaddr_in *sin = (struct sockaddr_in *) ai->ai_addr;
+          ret = inet_ntop (AF_INET, &sin->sin_addr, buf, sizeof (buf));
+          port = sin->sin_port;
+        }
+        break;
+      case AF_INET6:
+        {
+          struct sockaddr_in6 *sin = (struct sockaddr_in6 *) ai->ai_addr;
+          ret = inet_ntop (AF_INET6, &sin->sin6_addr, buf, sizeof (buf));
+          port = sin->sin6_port;
+        }
+        break;
+      default:
+        errno = EAFNOSUPPORT;
+        ret = NULL;
+      }
+    if (ret == NULL)
+        fprintf (out, "error: inet_top failed: %m\n");
+    else
+      fprintf (out, " %s %u\n", buf, ntohs (port));
+  }
+}
+
+/* Format all the addresses in one address family.  */
+static void
+format_ai_family (FILE *out, struct addrinfo *ai, int family)
+{
+  while (ai)
+    {
+      if (ai->ai_family == family)
+        format_ai_one (out, ai);
+      ai = ai->ai_next;
+    }
+}
+
+char *
+support_format_addrinfo (struct addrinfo *ai, int ret)
+{
+  int errno_copy = errno;
+
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+  if (ret != 0)
+    {
+      fprintf (mem.out, "error: %s\n", gai_strerror (ret));
+      if (ret == EAI_SYSTEM)
+        {
+          errno = errno_copy;
+          fprintf (mem.out, "error: %m\n");
+        }
+    }
+  else
+    {
+      format_ai_flags (mem.out, ai);
+      format_ai_canonname (mem.out, ai);
+      format_ai_family (mem.out, ai, AF_INET);
+      format_ai_family (mem.out, ai, AF_INET6);
+    }
+
+  xfclose_memstream (&mem);
+  return mem.buffer;
+}
diff --git a/support/support_format_dns_packet.c b/support/support_format_dns_packet.c
new file mode 100644
index 0000000..2992c57
--- /dev/null
+++ b/support/support_format_dns_packet.c
@@ -0,0 +1,222 @@
+/* Convert a DNS packet to a human-readable representation.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <arpa/inet.h>
+#include <resolv.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+struct in_buffer
+{
+  const unsigned char *data;
+  size_t size;
+};
+
+static inline bool
+extract_8 (struct in_buffer *in, unsigned char *value)
+{
+  if (in->size == 0)
+    return false;
+  *value = in->data[0];
+  ++in->data;
+  --in->size;
+  return true;
+}
+
+static inline bool
+extract_16 (struct in_buffer *in, unsigned short *value)
+{
+  if (in->size < 2)
+    return false;
+  *value = (in->data[0] << 8) | in->data[1];
+  in->data += 2;
+  in->size -= 2;
+  return true;
+}
+
+static inline bool
+extract_32 (struct in_buffer *in, unsigned *value)
+{
+  if (in->size < 4)
+    return false;
+  unsigned a = in->data[0];
+  unsigned b = in->data[1];
+  unsigned c = in->data[2];
+  unsigned d = in->data[3];
+  *value = (a << 24) | (b << 16) | (c << 8) | d;
+  in->data += 4;
+  in->size -= 4;
+  return true;
+}
+
+static inline bool
+extract_bytes (struct in_buffer *in, size_t length, struct in_buffer *value)
+{
+  if (in->size < length)
+    return false;
+  *value = (struct in_buffer) {in->data, length};
+  in->data += length;
+  in->size -= length;
+  return true;
+}
+
+struct dname
+{
+  char name[MAXDNAME + 1];
+};
+
+static bool
+extract_name (struct in_buffer full, struct in_buffer *in, struct dname *value)
+{
+  const unsigned char *full_end = full.data + full.size;
+  /* Sanity checks; these indicate buffer misuse.  */
+  TEST_VERIFY_EXIT
+    (!(in->data < full.data || in->data > full_end
+       || in->size > (size_t) (full_end - in->data)));
+  int ret = dn_expand (full.data, full_end, in->data,
+                       value->name, sizeof (value->name));
+  if (ret < 0)
+    return false;
+  in->data += ret;
+  in->size -= ret;
+  return true;
+}
+
+char *
+support_format_dns_packet (const unsigned char *buffer, size_t length)
+{
+  struct in_buffer full = { buffer, length };
+  struct in_buffer in = full;
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+
+  unsigned short txnid;
+  unsigned short flags;
+  unsigned short qdcount;
+  unsigned short ancount;
+  unsigned short nscount;
+  unsigned short adcount;
+  if (!(extract_16 (&in, &txnid)
+        && extract_16 (&in, &flags)
+        && extract_16 (&in, &qdcount)
+        && extract_16 (&in, &ancount)
+        && extract_16 (&in, &nscount)
+        && extract_16 (&in, &adcount)))
+    {
+      fprintf (mem.out, "error: could not parse DNS header\n");
+      goto out;
+    }
+  if (qdcount != 1)
+    {
+      fprintf (mem.out, "error: question count is %d, not 1\n", qdcount);
+      goto out;
+    }
+  struct dname qname;
+  if (!extract_name (full, &in, &qname))
+    {
+      fprintf (mem.out, "error: malformed QNAME\n");
+      goto out;
+    }
+  unsigned short qtype;
+  unsigned short qclass;
+  if (!(extract_16 (&in, &qtype)
+        && extract_16 (&in, &qclass)))
+    {
+      fprintf (mem.out, "error: malformed question\n");
+      goto out;
+    }
+  if (qtype != T_A && qtype != T_AAAA && qtype != T_PTR)
+    {
+      fprintf (mem.out, "error: unsupported QTYPE %d\n", qtype);
+      goto out;
+    }
+
+  fprintf (mem.out, "name: %s\n", qname.name);
+
+  for (int i = 0; i < ancount; ++i)
+    {
+      struct dname rname;
+      if (!extract_name (full, &in, &rname))
+        {
+          fprintf (mem.out, "error: malformed record name\n");
+          goto out;
+        }
+      unsigned short rtype;
+      unsigned short rclass;
+      unsigned ttl;
+      unsigned short rdlen;
+      struct in_buffer rdata;
+      if (!(extract_16 (&in, &rtype)
+            && extract_16 (&in, &rclass)
+            && extract_32 (&in, &ttl)
+            && extract_16 (&in, &rdlen)
+            && extract_bytes (&in, rdlen, &rdata)))
+        {
+          fprintf (mem.out, "error: malformed record header\n");
+          goto out;
+        }
+      /* Skip non-matching record types.  */
+      if ((rtype != qtype && rtype != T_CNAME) || rclass != qclass)
+        continue;
+      switch (rtype)
+        {
+        case T_A:
+          if (rdlen == 4)
+              fprintf (mem.out, "address: %d.%d.%d.%d\n",
+                       rdata.data[0],
+                       rdata.data[1],
+                       rdata.data[2],
+                       rdata.data[3]);
+          else
+            fprintf (mem.out, "error: A record of size %d: %s\n",
+                     rdlen, rname.name);
+          break;
+        case T_AAAA:
+          {
+            if (rdlen == 16)
+              {
+                char buf[100];
+                if (inet_ntop (AF_INET6, rdata.data, buf, sizeof (buf)) == NULL)
+                  fprintf (mem.out, "error: AAAA record decoding failed: %m\n");
+                else
+                  fprintf (mem.out, "address: %s\n", buf);
+              }
+            else
+              fprintf (mem.out, "error: AAAA record of size %d: %s\n",
+                       rdlen, rname.name);
+          }
+          break;
+        case T_CNAME:
+        case T_PTR:
+          {
+            struct dname name;
+            if (extract_name (full, &rdata, &name))
+              fprintf (mem.out, "name: %s\n", name.name);
+            else
+              fprintf (mem.out, "error: malformed CNAME/PTR record\n");
+          }
+        }
+    }
+
+ out:
+  xfclose_memstream (&mem);
+  return mem.buffer;
+}
diff --git a/support/support_format_herrno.c b/support/support_format_herrno.c
new file mode 100644
index 0000000..493d6ae
--- /dev/null
+++ b/support/support_format_herrno.c
@@ -0,0 +1,45 @@
+/* Convert a h_errno error code to a string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <support/support.h>
+
+char *
+support_format_herrno (int code)
+{
+  const char *errstr;
+  switch (code)
+    {
+    case HOST_NOT_FOUND:
+      errstr = "HOST_NOT_FOUND";
+      break;
+    case NO_ADDRESS:
+      errstr = "NO_ADDRESS";
+      break;
+    case NO_RECOVERY:
+      errstr = "NO_RECOVERY";
+      break;
+    case TRY_AGAIN:
+      errstr = "TRY_AGAIN";
+      break;
+    default:
+      return xasprintf ("<invalid h_errno value %d>\n", code);
+    }
+  return xstrdup (errstr);
+}
diff --git a/support/support_format_hostent.c b/support/support_format_hostent.c
new file mode 100644
index 0000000..5b5f260
--- /dev/null
+++ b/support/support_format_hostent.c
@@ -0,0 +1,75 @@
+/* Convert a struct hostent object to a string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+static int
+address_length (int family)
+{
+  switch (family)
+    {
+    case AF_INET:
+      return 4;
+    case AF_INET6:
+      return 16;
+    }
+  return -1;
+}
+
+char *
+support_format_hostent (struct hostent *h)
+{
+  if (h == NULL)
+    {
+      char *value = support_format_herrno (h_errno);
+      char *result = xasprintf ("error: %s\n", value);
+      free (value);
+      return result;
+    }
+
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+
+  fprintf (mem.out, "name: %s\n", h->h_name);
+  for (char **alias = h->h_aliases; *alias != NULL; ++alias)
+    fprintf (mem.out, "alias: %s\n", *alias);
+  for (unsigned i = 0; h->h_addr_list[i] != NULL; ++i)
+    {
+      char buf[128];
+      if (inet_ntop (h->h_addrtype, h->h_addr_list[i],
+                     buf, sizeof (buf)) == NULL)
+        fprintf (mem.out, "error: inet_ntop failed: %m\n");
+      else
+        fprintf (mem.out, "address: %s\n", buf);
+    }
+  if (h->h_length != address_length (h->h_addrtype))
+    {
+      char *family = support_format_address_family (h->h_addrtype);
+      fprintf (mem.out, "error: invalid address length %d for %s\n",
+               h->h_length, family);
+      free (family);
+    }
+
+  xfclose_memstream (&mem);
+  return mem.buffer;
+}
diff --git a/support/support_format_netent.c b/support/support_format_netent.c
new file mode 100644
index 0000000..020f572
--- /dev/null
+++ b/support/support_format_netent.c
@@ -0,0 +1,52 @@
+/* Convert a struct netent object to a string.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/format_nss.h>
+
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <support/support.h>
+#include <support/xmemstream.h>
+
+char *
+support_format_netent (struct netent *e)
+{
+  if (e == NULL)
+    {
+      char *value = support_format_herrno (h_errno);
+      char *result = xasprintf ("error: %s\n", value);
+      free (value);
+      return result;
+    }
+
+  struct xmemstream mem;
+  xopen_memstream (&mem);
+
+  if (e->n_name != NULL)
+    fprintf (mem.out, "name: %s\n", e->n_name);
+  for (char **ap = e->n_aliases; *ap != NULL; ++ap)
+    fprintf (mem.out, "alias: %s\n", *ap);
+  if (e->n_addrtype != AF_INET)
+    fprintf (mem.out, "addrtype: %d\n", e->n_addrtype);
+  /* On alpha, e->n_net is an unsigned long.  */
+  unsigned int n_net = e->n_net;
+  fprintf (mem.out, "net: 0x%08x\n", n_net);
+
+  xfclose_memstream (&mem);
+  return mem.buffer;
+}
diff --git a/support/support_isolate_in_subprocess.c b/support/support_isolate_in_subprocess.c
new file mode 100644
index 0000000..cf48614
--- /dev/null
+++ b/support/support_isolate_in_subprocess.c
@@ -0,0 +1,38 @@
+/* Run a function in a subprocess.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+
+void
+support_isolate_in_subprocess (void (*callback) (void *), void *closure)
+{
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      /* Child process.  */
+      callback (closure);
+      _exit (0);
+    }
+
+  /* Parent process.  */
+  int status;
+  xwaitpid (pid, &status, 0);
+  if (status != 0)
+    FAIL_EXIT1 ("child process exited with status %d", status);
+}
diff --git a/support/support_record_failure.c b/support/support_record_failure.c
new file mode 100644
index 0000000..684055c
--- /dev/null
+++ b/support/support_record_failure.c
@@ -0,0 +1,106 @@
+/* Global test failure counter.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+/* This structure keeps track of test failures.  The counter is
+   incremented on each failure.  The failed member is set to true if a
+   failure is detected, so that even if the counter wraps around to
+   zero, the failure of a test can be detected.
+
+   The init constructor function below puts *state on a shared
+   annonymous mapping, so that failure reports from subprocesses
+   propagate to the parent process.  */
+struct test_failures
+{
+  unsigned int counter;
+  unsigned int failed;
+};
+static struct test_failures *state;
+
+static __attribute__ ((constructor)) void
+init (void)
+{
+  void *ptr = mmap (NULL, sizeof (*state), PROT_READ | PROT_WRITE,
+                    MAP_ANONYMOUS | MAP_SHARED, -1, 0);
+  if (ptr == MAP_FAILED)
+    {
+      printf ("error: could not map %zu bytes: %m\n", sizeof (*state));
+      exit (1);
+    }
+  /* Zero-initialization of the struct is sufficient.  */
+  state = ptr;
+}
+
+void
+support_record_failure (void)
+{
+  if (state == NULL)
+    {
+      write_message
+        ("error: support_record_failure called without initialization\n");
+      _exit (1);
+    }
+  /* Relaxed MO is sufficient because we are only interested in the
+     values themselves, in isolation.  */
+  __atomic_store_n (&state->failed, 1, __ATOMIC_RELEASE);
+  __atomic_add_fetch (&state->counter, 1, __ATOMIC_RELEASE);
+}
+
+int
+support_report_failure (int status)
+{
+  if (state == NULL)
+    {
+      write_message
+        ("error: support_report_failure called without initialization\n");
+      return 1;
+    }
+
+  /* Relaxed MO is sufficient because acquire test result reporting
+     assumes that exiting from the main thread happens before the
+     error reporting via support_record_failure, which requires some
+     form of external synchronization.  */
+  bool failed = __atomic_load_n (&state->failed, __ATOMIC_RELAXED);
+  if (failed)
+    printf ("error: %u test failures\n",
+            __atomic_load_n (&state->counter, __ATOMIC_RELAXED));
+
+  if ((status == 0 || status == EXIT_UNSUPPORTED) && failed)
+    /* If we have a recorded failure, it overrides a non-failure
+       report from the test function.  */
+    status = 1;
+  return status;
+}
+
+void
+support_record_failure_reset (void)
+{
+  /* Only used for testing the test framework, with external
+     synchronization, but use release MO for consistency.  */
+  __atomic_store_n (&state->failed, 0, __ATOMIC_RELAXED);
+  __atomic_add_fetch (&state->counter, 0, __ATOMIC_RELAXED);
+}
diff --git a/support/support_run_diff.c b/support/support_run_diff.c
new file mode 100644
index 0000000..f5155de
--- /dev/null
+++ b/support/support_run_diff.c
@@ -0,0 +1,76 @@
+/* Invoke the system diff tool to compare two strings.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/run_diff.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <support/temp_file.h>
+#include <support/xunistd.h>
+#include <sys/wait.h>
+
+static char *
+write_to_temp_file (const char *prefix, const char *str)
+{
+  char *template = xasprintf ("run_diff-%s", prefix);
+  char *name = NULL;
+  int fd = create_temp_file (template, &name);
+  TEST_VERIFY_EXIT (fd >= 0);
+  free (template);
+  xwrite (fd, str, strlen (str));
+  xclose (fd);
+  return name;
+}
+
+void
+support_run_diff (const char *left_label, const char *left,
+                  const char *right_label, const char *right)
+{
+  /* Ensure that the diff command output is ordered properly with
+     standard output.  */
+  TEST_VERIFY_EXIT (fflush (stdout) == 0);
+
+  char *left_path = write_to_temp_file ("left-diff", left);
+  char *right_path = write_to_temp_file ("right-diff", right);
+
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      execlp ("diff", "diff", "-u",
+              "--label", left_label, "--label", right_label,
+              "--", left_path, right_path,
+              NULL);
+      _exit (17);
+    }
+  else
+    {
+      int status;
+      xwaitpid (pid, &status, 0);
+      if (!WIFEXITED (status) || WEXITSTATUS (status) != 1)
+        printf ("warning: could not run diff, exit status: %d\n"
+                "*** %s ***\n%s\n"
+                "*** %s ***\n%s\n",
+                status, left_label, left, right_label, right);
+    }
+
+  free (right_path);
+  free (left_path);
+}
diff --git a/support/support_shared_allocate.c b/support/support_shared_allocate.c
new file mode 100644
index 0000000..61d088e
--- /dev/null
+++ b/support/support_shared_allocate.c
@@ -0,0 +1,57 @@
+/* Allocate a memory region shared across processes.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <support/support.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+
+/* Header for the allocation.  It contains the size of the allocation
+   for subsequent unmapping.  */
+struct header
+{
+  size_t total_size;
+  char data[] __attribute__ ((aligned (__alignof__ (max_align_t))));
+};
+
+void *
+support_shared_allocate (size_t size)
+{
+  size_t total_size = size + offsetof (struct header, data);
+  if (total_size < size)
+    {
+      errno = ENOMEM;
+      oom_error (__func__, size);
+      return NULL;
+    }
+  else
+    {
+      struct header *result = xmmap (NULL, total_size, PROT_READ | PROT_WRITE,
+                                     MAP_ANONYMOUS | MAP_SHARED, -1);
+      result->total_size = total_size;
+      return &result->data;
+    }
+}
+
+void
+support_shared_free (void *data)
+{
+  struct header *header = data - offsetof (struct header, data);
+  xmunmap (header, header->total_size);
+}
diff --git a/support/support_test_main.c b/support/support_test_main.c
new file mode 100644
index 0000000..914d64f
--- /dev/null
+++ b/support/support_test_main.c
@@ -0,0 +1,423 @@
+/* Main worker function for the test driver.
+   Copyright (C) 1998-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/test-driver.h>
+#include <support/check.h>
+#include <support/temp_file-internal.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <getopt.h>
+#include <malloc.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <sys/resource.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+static const struct option default_options[] =
+{
+  TEST_DEFAULT_OPTIONS
+  { NULL, 0, NULL, 0 }
+};
+
+/* Show people how to run the program.  */
+static void
+usage (const struct option *options)
+{
+  size_t i;
+
+  printf ("Usage: %s [options]\n"
+          "\n"
+          "Environment Variables:\n"
+          "  TIMEOUTFACTOR          An integer used to scale the timeout\n"
+          "  TMPDIR                 Where to place temporary files\n"
+          "  TEST_COREDUMPS         Do not disable coredumps if set\n"
+          "\n",
+          program_invocation_short_name);
+  printf ("Options:\n");
+  for (i = 0; options[i].name; ++i)
+    {
+      int indent;
+
+      indent = printf ("  --%s", options[i].name);
+      if (options[i].has_arg == required_argument)
+        indent += printf (" <arg>");
+      printf ("%*s", 25 - indent, "");
+      switch (options[i].val)
+        {
+        case 'v':
+          printf ("Increase the output verbosity");
+          break;
+        case OPT_DIRECT:
+          printf ("Run the test directly (instead of forking & monitoring)");
+          break;
+        case OPT_TESTDIR:
+          printf ("Override the TMPDIR env var");
+          break;
+        }
+      printf ("\n");
+    }
+}
+
+/* The PID of the test process.  */
+static pid_t test_pid;
+
+/* The cleanup handler passed to test_main.  */
+static void (*cleanup_function) (void);
+
+/* Timeout handler.  We kill the child and exit with an error.  */
+static void
+__attribute__ ((noreturn))
+signal_handler (int sig)
+{
+  int killed;
+  int status;
+
+  assert (test_pid > 1);
+  /* Kill the whole process group.  */
+  kill (-test_pid, SIGKILL);
+  /* In case setpgid failed in the child, kill it individually too.  */
+  kill (test_pid, SIGKILL);
+
+  /* Wait for it to terminate.  */
+  int i;
+  for (i = 0; i < 5; ++i)
+    {
+      killed = waitpid (test_pid, &status, WNOHANG|WUNTRACED);
+      if (killed != 0)
+        break;
+
+      /* Delay, give the system time to process the kill.  If the
+         nanosleep() call return prematurely, all the better.  We
+         won't restart it since this probably means the child process
+         finally died.  */
+      struct timespec ts;
+      ts.tv_sec = 0;
+      ts.tv_nsec = 100000000;
+      nanosleep (&ts, NULL);
+    }
+  if (killed != 0 && killed != test_pid)
+    {
+      printf ("Failed to kill test process: %m\n");
+      exit (1);
+    }
+
+  if (cleanup_function != NULL)
+    cleanup_function ();
+
+  if (sig == SIGINT)
+    {
+      signal (sig, SIG_DFL);
+      raise (sig);
+    }
+
+  if (killed == 0 || (WIFSIGNALED (status) && WTERMSIG (status) == SIGKILL))
+    puts ("Timed out: killed the child process");
+  else if (WIFSTOPPED (status))
+    printf ("Timed out: the child process was %s\n",
+            strsignal (WSTOPSIG (status)));
+  else if (WIFSIGNALED (status))
+    printf ("Timed out: the child process got signal %s\n",
+            strsignal (WTERMSIG (status)));
+  else
+    printf ("Timed out: killed the child process but it exited %d\n",
+            WEXITSTATUS (status));
+
+  /* Exit with an error.  */
+  exit (1);
+}
+
+/* Run test_function or test_function_argv.  */
+static int
+run_test_function (int argc, char **argv, const struct test_config *config)
+{
+  if (config->test_function != NULL)
+    return config->test_function ();
+  else if (config->test_function_argv != NULL)
+    return config->test_function_argv (argc, argv);
+  else
+    {
+      printf ("error: no test function defined\n");
+      exit (1);
+    }
+}
+
+static bool test_main_called;
+
+const char *test_dir = NULL;
+unsigned int test_verbose = 0;
+
+/* If test failure reporting has been linked in, it may contribute
+   additional test failures.  */
+static int
+adjust_exit_status (int status)
+{
+  if (support_report_failure != NULL)
+    return support_report_failure (status);
+  return status;
+}
+
+int
+support_test_main (int argc, char **argv, const struct test_config *config)
+{
+  if (test_main_called)
+    {
+      printf ("error: test_main called for a second time\n");
+      exit (1);
+    }
+  test_main_called = true;
+  const struct option *options;
+  if (config->options != NULL)
+    options = config->options;
+  else
+    options = default_options;
+
+  cleanup_function = config->cleanup_function;
+
+  int direct = 0;       /* Directly call the test function?  */
+  int status;
+  int opt;
+  unsigned int timeoutfactor = 1;
+  pid_t termpid;
+
+  if (!config->no_mallopt)
+    {
+      /* Make uses of freed and uninitialized memory known.  Do not
+         pull in a definition for mallopt if it has not been defined
+         already.  */
+      extern __typeof__ (mallopt) mallopt __attribute__ ((weak));
+      if (mallopt != NULL)
+        mallopt (M_PERTURB, 42);
+    }
+
+  while ((opt = getopt_long (argc, argv, "+", options, NULL)) != -1)
+    switch (opt)
+      {
+      case '?':
+        usage (options);
+        exit (1);
+      case 'v':
+        ++test_verbose;
+        break;
+      case OPT_DIRECT:
+        direct = 1;
+        break;
+      case OPT_TESTDIR:
+        test_dir = optarg;
+        break;
+      default:
+        if (config->cmdline_function != NULL)
+          config->cmdline_function (opt);
+      }
+
+  /* If set, read the test TIMEOUTFACTOR value from the environment.
+     This value is used to scale the default test timeout values. */
+  char *envstr_timeoutfactor = getenv ("TIMEOUTFACTOR");
+  if (envstr_timeoutfactor != NULL)
+    {
+      char *envstr_conv = envstr_timeoutfactor;
+      unsigned long int env_fact;
+
+      env_fact = strtoul (envstr_timeoutfactor, &envstr_conv, 0);
+      if (*envstr_conv == '\0' && envstr_conv != envstr_timeoutfactor)
+        timeoutfactor = MAX (env_fact, 1);
+    }
+
+  /* Set TMPDIR to specified test directory.  */
+  if (test_dir != NULL)
+    {
+      setenv ("TMPDIR", test_dir, 1);
+
+      if (chdir (test_dir) < 0)
+        {
+          printf ("chdir: %m\n");
+          exit (1);
+        }
+    }
+  else
+    {
+      test_dir = getenv ("TMPDIR");
+      if (test_dir == NULL || test_dir[0] == '\0')
+        test_dir = "/tmp";
+    }
+  if (support_set_test_dir != NULL)
+    support_set_test_dir (test_dir);
+
+  int timeout = config->timeout;
+  if (timeout == 0)
+    timeout =  DEFAULT_TIMEOUT;
+
+  /* Make sure we see all message, even those on stdout.  */
+  setvbuf (stdout, NULL, _IONBF, 0);
+
+  /* Make sure temporary files are deleted.  */
+  if (support_delete_temp_files != NULL)
+      atexit (support_delete_temp_files);
+
+  /* Correct for the possible parameters.  */
+  argv[optind - 1] = argv[0];
+  argv += optind - 1;
+  argc -= optind - 1;
+
+  /* Call the initializing function, if one is available.  */
+  if (config->prepare_function != NULL)
+    config->prepare_function (argc, argv);
+
+  const char *envstr_direct = getenv ("TEST_DIRECT");
+  if (envstr_direct != NULL)
+    {
+      FILE *f = fopen (envstr_direct, "w");
+      if (f == NULL)
+        {
+          printf ("cannot open TEST_DIRECT output file '%s': %m\n",
+                  envstr_direct);
+          exit (1);
+        }
+
+      fprintf (f, "timeout=%u\ntimeoutfactor=%u\n",
+               config->timeout, timeoutfactor);
+      if (config->expected_status != 0)
+        fprintf (f, "exit=%u\n", config->expected_status);
+      if (config->expected_signal != 0)
+        fprintf (f, "signal=%s\n", strsignal (config->expected_signal));
+
+      if (support_print_temp_files != NULL)
+        support_print_temp_files (f);
+
+      fclose (f);
+      direct = 1;
+    }
+
+  bool disable_coredumps;
+  {
+    const char *coredumps = getenv ("TEST_COREDUMPS");
+    disable_coredumps = coredumps == NULL || coredumps[0] == '\0';
+  }
+
+  /* If we are not expected to fork run the function immediately.  */
+  if (direct)
+    return adjust_exit_status (run_test_function (argc, argv, config));
+
+  /* Set up the test environment:
+     - prevent core dumps
+     - set up the timer
+     - fork and execute the function.  */
+
+  test_pid = fork ();
+  if (test_pid == 0)
+    {
+      /* This is the child.  */
+      if (disable_coredumps)
+        {
+          /* Try to avoid dumping core.  This is necessary because we
+             run the test from the source tree, and the coredumps
+             would end up there (and not in the build tree).  */
+          struct rlimit core_limit;
+          core_limit.rlim_cur = 0;
+          core_limit.rlim_max = 0;
+          setrlimit (RLIMIT_CORE, &core_limit);
+        }
+
+      /* We put the test process in its own pgrp so that if it bogusly
+         generates any job control signals, they won't hit the whole build.  */
+      if (setpgid (0, 0) != 0)
+        printf ("Failed to set the process group ID: %m\n");
+
+      /* Execute the test function and exit with the return value.   */
+      exit (run_test_function (argc, argv, config));
+    }
+  else if (test_pid < 0)
+    {
+      printf ("Cannot fork test program: %m\n");
+      exit (1);
+    }
+
+  /* Set timeout.  */
+  signal (SIGALRM, signal_handler);
+  alarm (timeout * timeoutfactor);
+
+  /* Make sure we clean up if the wrapper gets interrupted.  */
+  signal (SIGINT, signal_handler);
+
+  /* Wait for the regular termination.  */
+  termpid = TEMP_FAILURE_RETRY (waitpid (test_pid, &status, 0));
+  if (termpid == -1)
+    {
+      printf ("Waiting for test program failed: %m\n");
+      exit (1);
+    }
+  if (termpid != test_pid)
+    {
+      printf ("Oops, wrong test program terminated: expected %ld, got %ld\n",
+              (long int) test_pid, (long int) termpid);
+      exit (1);
+    }
+
+  /* Process terminated normaly without timeout etc.  */
+  if (WIFEXITED (status))
+    {
+      if (config->expected_status == 0)
+        {
+          if (config->expected_signal == 0)
+            /* Exit with the return value of the test.  */
+            return adjust_exit_status (WEXITSTATUS (status));
+          else
+            {
+              printf ("Expected signal '%s' from child, got none\n",
+                      strsignal (config->expected_signal));
+              exit (1);
+            }
+        }
+      else
+        {
+          /* Non-zero exit status is expected */
+          if (WEXITSTATUS (status) != config->expected_status)
+            {
+              printf ("Expected status %d, got %d\n",
+                      config->expected_status, WEXITSTATUS (status));
+              exit (1);
+            }
+        }
+      return adjust_exit_status (0);
+    }
+  /* Process was killed by timer or other signal.  */
+  else
+    {
+      if (config->expected_signal == 0)
+        {
+          printf ("Didn't expect signal from child: got `%s'\n",
+                  strsignal (WTERMSIG (status)));
+          exit (1);
+        }
+      else if (WTERMSIG (status) != config->expected_signal)
+        {
+          printf ("Incorrect signal from child: got `%s', need `%s'\n",
+                  strsignal (WTERMSIG (status)),
+                  strsignal (config->expected_signal));
+          exit (1);
+        }
+
+      return adjust_exit_status (0);
+    }
+}
diff --git a/support/support_test_verify_impl.c b/support/support_test_verify_impl.c
new file mode 100644
index 0000000..5bae38f
--- /dev/null
+++ b/support/support_test_verify_impl.c
@@ -0,0 +1,33 @@
+/* Implementation of the TEST_VERIFY and TEST_VERIFY_EXIT macros.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+void
+support_test_verify_impl (int status, const char *file, int line,
+                          const char *expr)
+{
+  support_record_failure ();
+  printf ("error: %s:%d: not true: %s\n", file, line, expr);
+  if (status >= 0)
+    exit (status);
+
+}
diff --git a/support/support_write_file_string.c b/support/support_write_file_string.c
new file mode 100644
index 0000000..48e8959
--- /dev/null
+++ b/support/support_write_file_string.c
@@ -0,0 +1,39 @@
+/* Write a string to a file.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <fcntl.h>
+#include <string.h>
+#include <support/check.h>
+#include <xunistd.h>
+
+void
+support_write_file_string (const char *path, const char *contents)
+{
+  int fd = xopen (path, O_CREAT | O_TRUNC | O_WRONLY, 0666);
+  const char *end = contents + strlen (contents);
+  for (const char *p = contents; p < end; )
+    {
+      ssize_t ret = write (fd, p, end - p);
+      if (ret < 0)
+        FAIL_EXIT1 ("cannot write to \"%s\": %m", path);
+      if (ret == 0)
+        FAIL_EXIT1 ("zero-length write to \"%s\"", path);
+      p += ret;
+    }
+  xclose (fd);
+}
diff --git a/support/temp_file-internal.h b/support/temp_file-internal.h
new file mode 100644
index 0000000..fb6cceb
--- /dev/null
+++ b/support/temp_file-internal.h
@@ -0,0 +1,31 @@
+/* Internal weak declarations for temporary file handling.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_TEMP_FILE_INTERNAL_H
+#define SUPPORT_TEMP_FILE_INTERNAL_H
+
+/* These functions are called by the test driver if they are
+   defined.  Tests should not call them directly.  */
+
+#include <stdio.h>
+
+void support_set_test_dir (const char *name) __attribute__ ((weak));
+void support_delete_temp_files (void) __attribute__ ((weak));
+void support_print_temp_files (FILE *) __attribute__ ((weak));
+
+#endif /* SUPPORT_TEMP_FILE_INTERNAL_H */
diff --git a/support/temp_file.c b/support/temp_file.c
new file mode 100644
index 0000000..fdb2477
--- /dev/null
+++ b/support/temp_file.c
@@ -0,0 +1,132 @@
+/* Temporary file handling for tests.
+   Copyright (C) 1998-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This is required to get an mkstemp which can create large files on
+   some 32-bit platforms. */
+#define _FILE_OFFSET_BITS 64
+
+#include <support/temp_file.h>
+#include <support/temp_file-internal.h>
+#include <support/support.h>
+
+#include <paths.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* List of temporary files.  */
+static struct temp_name_list
+{
+  struct temp_name_list *next;
+  char *name;
+  pid_t owner;
+} *temp_name_list;
+
+/* Location of the temporary files.  Set by the test skeleton via
+   support_set_test_dir.  The string is not be freed.  */
+static const char *test_dir = _PATH_TMP;
+
+void
+add_temp_file (const char *name)
+{
+  struct temp_name_list *newp
+    = (struct temp_name_list *) xcalloc (sizeof (*newp), 1);
+  char *newname = strdup (name);
+  if (newname != NULL)
+    {
+      newp->name = newname;
+      newp->next = temp_name_list;
+      newp->owner = getpid ();
+      temp_name_list = newp;
+    }
+  else
+    free (newp);
+}
+
+int
+create_temp_file (const char *base, char **filename)
+{
+  char *fname;
+  int fd;
+
+  fname = (char *) xmalloc (strlen (test_dir) + 1 + strlen (base)
+			    + sizeof ("XXXXXX"));
+  strcpy (stpcpy (stpcpy (stpcpy (fname, test_dir), "/"), base), "XXXXXX");
+
+  fd = mkstemp (fname);
+  if (fd == -1)
+    {
+      printf ("cannot open temporary file '%s': %m\n", fname);
+      free (fname);
+      return -1;
+    }
+
+  add_temp_file (fname);
+  if (filename != NULL)
+    *filename = fname;
+  else
+    free (fname);
+
+  return fd;
+}
+
+/* Helper functions called by the test skeleton follow.  */
+
+void
+support_set_test_dir (const char *path)
+{
+  test_dir = path;
+}
+
+void
+support_delete_temp_files (void)
+{
+  pid_t pid = getpid ();
+  while (temp_name_list != NULL)
+    {
+      /* Only perform the removal if the path was registed in the same
+	 process, as identified by the PID.  (This assumes that the
+	 parent process which registered the temporary file sticks
+	 around, to prevent PID reuse.)  */
+      if (temp_name_list->owner == pid)
+	{
+	  if (remove (temp_name_list->name) != 0)
+	    printf ("warning: could not remove temporary file: %s: %m\n",
+		    temp_name_list->name);
+	}
+      free (temp_name_list->name);
+
+      struct temp_name_list *next = temp_name_list->next;
+      free (temp_name_list);
+      temp_name_list = next;
+    }
+}
+
+void
+support_print_temp_files (FILE *f)
+{
+  if (temp_name_list != NULL)
+    {
+      struct temp_name_list *n;
+      fprintf (f, "temp_files=(\n");
+      for (n = temp_name_list; n != NULL; n = n->next)
+        fprintf (f, "  '%s'\n", n->name);
+      fprintf (f, ")\n");
+    }
+}
diff --git a/support/temp_file.h b/support/temp_file.h
new file mode 100644
index 0000000..6fed8df
--- /dev/null
+++ b/support/temp_file.h
@@ -0,0 +1,37 @@
+/* Declarations for temporary file handling.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_TEMP_FILE_H
+#define SUPPORT_TEMP_FILE_H
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Schedule a temporary file for deletion on exit.  */
+void add_temp_file (const char *name);
+
+/* Create a temporary file.  Return the opened file descriptor on
+   success, or -1 on failure.  Write the file name to *FILENAME if
+   FILENAME is not NULL.  In this case, the caller is expected to free
+   *FILENAME.  */
+int create_temp_file (const char *base, char **filename);
+
+__END_DECLS
+
+#endif /* SUPPORT_TEMP_FILE_H */
diff --git a/support/test-driver.c b/support/test-driver.c
new file mode 100644
index 0000000..482066d
--- /dev/null
+++ b/support/test-driver.c
@@ -0,0 +1,156 @@
+/* Main function for test programs.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* This file should be included from test cases.  It will define a
+   main function which provides the test wrapper.
+
+   It assumes that the test case defines a function
+
+     int do_test (void);
+
+   and arranges for that function being called under the test wrapper.
+   The do_test function should return 0 to indicate a passing test, 1
+   to indicate a failing test, or 77 to indicate an unsupported test.
+   Other result values could be used to indicate a failing test, but
+   the result of the expression is passed to exit and exit only
+   returns the lower 8 bits of its input.  A non-zero return with some
+   values could cause a test to incorrectly be considered passing when
+   it really failed.  For this reason, the function should always
+   return 0 (EXIT_SUCCESS), 1 (EXIT_FAILURE), or 77
+   (EXIT_UNSUPPORTED).
+
+   The test function may print out diagnostic or warning messages as well
+   as messages about failures.  These messages should be printed to stdout
+   and not stderr so that the output is properly ordered with respect to
+   the rest of the glibc testsuite run output.
+
+   Several preprocessors macros can be defined before including this
+   file.
+
+   The name of the do_test function can be changed with the
+   TEST_FUNCTION macro.  It must expand to the desired function name.
+
+   If the test case needs access to command line parameters, it must
+   define the TEST_FUNCTION_ARGV macro with the name of the test
+   function.  It must have the following type:
+
+     int TEST_FUNCTION_ARGV (int argc, char **argv);
+
+   This overrides the do_test default function and is incompatible
+   with the TEST_FUNCTION macro.
+
+   If PREPARE is defined, it must expand to the name of a function of
+   the type
+
+     void PREPARE (int argc, char **);
+
+   This function will be called early, after parsing the command line,
+   but before running the test, in the parent process which acts as
+   the test supervisor.
+
+   If CLEANUP_HANDLER is defined, it must expand to the name of a
+   function of the type
+
+     void CLEANUP_HANDLER (void);
+
+   This function will be called from the timeout (SIGALRM) signal
+   handler.
+
+   If EXPECTED_SIGNAL is defined, it must expanded to a constant which
+   denotes the expected signal number.
+
+   If EXPECTED_STATUS is defined, it must expand to the expected exit
+   status.
+
+   If TIMEOUT is defined, it must be positive constant.  It overrides
+   the default test timeout and is measured in seconds.
+
+   If TEST_NO_MALLOPT is defined, the test wrapper will not call
+   mallopt.
+
+   Custom command line handling can be implemented by defining the
+   CMDLINE_OPTION macro (after including the <getopt.h> header; this
+   requires _GNU_SOURCE to be defined).  This macro must expand to a
+   to a comma-separated list of braced initializers for struct option
+   from <getopt.h>, with a trailing comma.  CMDLINE_PROCESS can be
+   defined as the name of a function which is called to process these
+   options.  The function is passed the option character/number and
+   has this type:
+
+     void CMDLINE_PROCESS (int);
+*/
+
+#include <support/test-driver.h>
+
+#include <string.h>
+
+int
+main (int argc, char **argv)
+{
+  struct test_config test_config;
+  memset (&test_config, 0, sizeof (test_config));
+
+#ifdef PREPARE
+  test_config.prepare_function = (PREPARE);
+#endif
+
+#if defined (TEST_FUNCTION) && defined (TEST_FUNCTON_ARGV)
+# error TEST_FUNCTION and TEST_FUNCTION_ARGV cannot be defined at the same time
+#endif
+#if defined (TEST_FUNCTION)
+  test_config.test_function = TEST_FUNCTION;
+#elif defined (TEST_FUNCTION_ARGV)
+  test_config.test_function_argv = TEST_FUNCTION_ARGV;
+#else
+  test_config.test_function = do_test;
+#endif
+
+#ifdef CLEANUP_HANDLER
+  test_config.cleanup_function = CLEANUP_HANDLER;
+#endif
+
+#ifdef EXPECTED_SIGNAL
+  test_config.expected_signal = (EXPECTED_SIGNAL);
+#endif
+
+#ifdef EXPECTED_STATUS
+  test_config.expected_status = (EXPECTED_STATUS);
+#endif
+
+#ifdef TEST_NO_MALLOPT
+  test_config.no_mallopt = 1;
+#endif
+
+#ifdef TIMEOUT
+  test_config.timeout = TIMEOUT;
+#endif
+
+#ifdef CMDLINE_OPTIONS
+  struct option options[] =
+    {
+      CMDLINE_OPTIONS
+      TEST_DEFAULT_OPTIONS
+    };
+  test_config.options = &options;
+#endif
+#ifdef CMDLINE_PROCESS
+  test_config.cmdline_function = CMDLINE_PROCESS;
+#endif
+
+  return support_test_main (argc, argv, &test_config);
+}
diff --git a/support/test-driver.h b/support/test-driver.h
new file mode 100644
index 0000000..af1971a
--- /dev/null
+++ b/support/test-driver.h
@@ -0,0 +1,74 @@
+/* Interfaces for the test driver.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_TEST_DRIVER_H
+#define SUPPORT_TEST_DRIVER_H
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+struct test_config
+{
+  void (*prepare_function) (int argc, char **argv);
+  int (*test_function) (void);
+  int (*test_function_argv) (int argc, char **argv);
+  void (*cleanup_function) (void);
+  void (*cmdline_function) (int);
+  const void *options;   /* Custom options if not NULL.  */
+  int timeout;           /* Test timeout in seconds.  */
+  int expected_status;   /* Expected exit status.  */
+  int expected_signal;   /* If non-zero, expect termination by signal.  */
+  char no_mallopt;       /* Boolean flag to disable mallopt.  */
+};
+
+enum
+  {
+    /* Test exit status which indicates that the feature is
+       unsupported. */
+    EXIT_UNSUPPORTED = 77,
+
+    /* Default timeout is twenty seconds.  Tests should normally
+       complete faster than this, but if they don't, that's abnormal
+       (a bug) anyways.  */
+    DEFAULT_TIMEOUT = 20,
+
+    /* Used for command line argument parsing.  */
+    OPT_DIRECT = 1000,
+    OPT_TESTDIR,
+  };
+
+/* Options provided by the test driver.  */
+#define TEST_DEFAULT_OPTIONS                            \
+  { "verbose", no_argument, NULL, 'v' },                \
+  { "direct", no_argument, NULL, OPT_DIRECT },          \
+  { "test-dir", required_argument, NULL, OPT_TESTDIR }, \
+
+/* The directory the test should use for temporary files.  */
+extern const char *test_dir;
+
+/* The number of --verbose arguments specified during program
+   invocation.  This variable can be used to control the verbosity of
+   tests.  */
+extern unsigned int test_verbose;
+
+int support_test_main (int argc, char **argv, const struct test_config *);
+
+__END_DECLS
+
+#endif /* SUPPORT_TEST_DRIVER_H */
diff --git a/support/tst-support-namespace.c b/support/tst-support-namespace.c
new file mode 100644
index 0000000..a50b074
--- /dev/null
+++ b/support/tst-support-namespace.c
@@ -0,0 +1,34 @@
+/* Test entering namespaces.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <support/namespace.h>
+
+static int
+do_test (void)
+{
+  if (support_become_root ())
+    printf ("info: acquired root-like privileges\n");
+  if (support_enter_network_namespace ())
+    printf ("info: entered network namespace\n");
+  if (support_in_uts_namespace ())
+    printf ("info: also entered UTS namespace\n");
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/tst-support_capture_subprocess.c b/support/tst-support_capture_subprocess.c
new file mode 100644
index 0000000..5672fba
--- /dev/null
+++ b/support/tst-support_capture_subprocess.c
@@ -0,0 +1,188 @@
+/* Test capturing output from a subprocess.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+/* Write one byte at *P to FD and advance *P.  Do nothing if *P is
+   '\0'.  */
+static void
+transfer (const unsigned char **p, int fd)
+{
+  if (**p != '\0')
+    {
+      TEST_VERIFY (write (fd, *p, 1) == 1);
+      ++*p;
+    }
+}
+
+/* Determine the order in which stdout and stderr are written.  */
+enum write_mode { out_first, err_first, interleave,
+                  write_mode_last =  interleave };
+
+/* Describe what to write in the subprocess.  */
+struct test
+{
+  char *out;
+  char *err;
+  enum write_mode write_mode;
+  int signal;
+  int status;
+};
+
+/* For use with support_capture_subprocess.  */
+static void
+callback (void *closure)
+{
+  const struct test *test = closure;
+  bool mode_ok = false;
+  switch (test->write_mode)
+    {
+    case out_first:
+      TEST_VERIFY (fputs (test->out, stdout) >= 0);
+      TEST_VERIFY (fflush (stdout) == 0);
+      TEST_VERIFY (fputs (test->err, stderr) >= 0);
+      TEST_VERIFY (fflush (stderr) == 0);
+      mode_ok = true;
+      break;
+    case err_first:
+      TEST_VERIFY (fputs (test->err, stderr) >= 0);
+      TEST_VERIFY (fflush (stderr) == 0);
+      TEST_VERIFY (fputs (test->out, stdout) >= 0);
+      TEST_VERIFY (fflush (stdout) == 0);
+      mode_ok = true;
+      break;
+    case interleave:
+      {
+        const unsigned char *pout = (const unsigned char *) test->out;
+        const unsigned char *perr = (const unsigned char *) test->err;
+        do
+          {
+            transfer (&pout, STDOUT_FILENO);
+            transfer (&perr, STDERR_FILENO);
+          }
+        while (*pout != '\0' || *perr != '\0');
+      }
+      mode_ok = true;
+      break;
+    }
+  TEST_VERIFY (mode_ok);
+
+  if (test->signal != 0)
+    raise (test->signal);
+  exit (test->status);
+}
+
+/* Create a heap-allocated random string of letters.  */
+static char *
+random_string (size_t length)
+{
+  char *result = xmalloc (length + 1);
+  for (size_t i = 0; i < length; ++i)
+    result[i] = 'a' + (rand () % 26);
+  result[length] = '\0';
+  return result;
+}
+
+/* Check that the specific stream from the captured subprocess matches
+   expectations.  */
+static void
+check_stream (const char *what, const struct xmemstream *stream,
+              const char *expected)
+{
+  if (strcmp (stream->buffer, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: captured %s data incorrect\n"
+              "  expected: %s\n"
+              "  actual:   %s\n",
+              what, expected, stream->buffer);
+    }
+  if (stream->length != strlen (expected))
+    {
+      support_record_failure ();
+      printf ("error: captured %s data length incorrect\n"
+              "  expected: %zu\n"
+              "  actual:   %zu\n",
+              what, strlen (expected), stream->length);
+    }
+}
+
+static int
+do_test (void)
+{
+  const int lengths[] = {0, 1, 17, 512, 20000, -1};
+
+  /* Test multiple combinations of support_capture_subprocess.
+
+     length_idx_stdout: Index into the lengths array above,
+       controls how many bytes are written by the subprocess to
+       standard output.
+     length_idx_stderr: Same for standard error.
+     write_mode: How standard output and standard error writes are
+       ordered.
+     signal: Exit with no signal if zero, with SIGTERM if one.
+     status: Process exit status: 0 if zero, 3 if one.  */
+  for (int length_idx_stdout = 0; lengths[length_idx_stdout] >= 0;
+       ++length_idx_stdout)
+    for (int length_idx_stderr = 0; lengths[length_idx_stderr] >= 0;
+         ++length_idx_stderr)
+      for (int write_mode = 0; write_mode < write_mode_last; ++write_mode)
+        for (int signal = 0; signal < 2; ++signal)
+          for (int status = 0; status < 2; ++status)
+            {
+              struct test test =
+                {
+                  .out = random_string (lengths[length_idx_stdout]),
+                  .err = random_string (lengths[length_idx_stderr]),
+                  .write_mode = write_mode,
+                  .signal = signal * SIGTERM, /* 0 or SIGTERM.  */
+                  .status = status * 3,       /* 0 or 3.  */
+                };
+              TEST_VERIFY (strlen (test.out) == lengths[length_idx_stdout]);
+              TEST_VERIFY (strlen (test.err) == lengths[length_idx_stderr]);
+
+              struct support_capture_subprocess result
+                = support_capture_subprocess (callback, &test);
+              check_stream ("stdout", &result.out, test.out);
+              check_stream ("stderr", &result.err, test.err);
+              if (test.signal != 0)
+                {
+                  TEST_VERIFY (WIFSIGNALED (result.status));
+                  TEST_VERIFY (WTERMSIG (result.status) == test.signal);
+                }
+              else
+                {
+                  TEST_VERIFY (WIFEXITED (result.status));
+                  TEST_VERIFY (WEXITSTATUS (result.status) == test.status);
+                }
+              support_capture_subprocess_free (&result);
+              free (test.out);
+              free (test.err);
+            }
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/tst-support_format_dns_packet.c b/support/tst-support_format_dns_packet.c
new file mode 100644
index 0000000..9c8589c
--- /dev/null
+++ b/support/tst-support_format_dns_packet.c
@@ -0,0 +1,101 @@
+/* Tests for the support_format_dns_packet function.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/format_nss.h>
+#include <support/run_diff.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void
+check_packet (const void *buffer, size_t length,
+              const char *name, const char *expected)
+{
+  char *actual = support_format_dns_packet (buffer, length);
+  if (strcmp (actual, expected) != 0)
+    {
+      support_record_failure ();
+      printf ("error: formatted packet does not match: %s\n", name);
+      support_run_diff ("expected", expected,
+                        "actual", actual);
+    }
+  free (actual);
+}
+
+static void
+test_aaaa_length (void)
+{
+  static const char packet[] =
+    /* Header: Response with two records.  */
+    "\x12\x34\x80\x00\x00\x01\x00\x02\x00\x00\x00\x00"
+    /* Question section.  www.example/IN/AAAA.  */
+    "\x03www\x07""example\x00\x00\x1c\x00\x01"
+    /* Answer section.  www.example AAAA [corrupted].  */
+    "\xc0\x0c"
+    "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x10"
+    "\x20\x01\x0d\xb8\x05\x06\x07\x08"
+    "\x11\x12\x13\x14\x15\x16\x17\x18"
+    /* www.example AAAA [corrupted].  */
+    "\xc0\x0c"
+    "\x00\x1c\x00\x01\x00\x00\x00\x00\x00\x11"
+    "\x01\x02\x03\x04\x05\x06\x07\x08"
+    "\x11\x12\x13\x14\x15\x16\x17\x18" "\xff";
+  check_packet (packet, sizeof (packet) - 1, __func__,
+                "name: www.example\n"
+                "address: 2001:db8:506:708:1112:1314:1516:1718\n"
+                "error: AAAA record of size 17: www.example\n");
+}
+
+static void
+test_multiple_cnames (void)
+{
+  static const char packet[] =
+    /* Header: Response with three records.  */
+    "\x12\x34\x80\x00\x00\x01\x00\x03\x00\x00\x00\x00"
+    /* Question section.  www.example/IN/A.  */
+    "\x03www\x07""example\x00\x00\x01\x00\x01"
+    /* Answer section.  www.example CNAME www1.example.  */
+    "\xc0\x0c"
+    "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07"
+    "\x04www1\xc0\x10"
+    /* www1 CNAME www2.  */
+    "\x04www1\xc0\x10"
+    "\x00\x05\x00\x01\x00\x00\x00\x00\x00\x07"
+    "\x04www2\xc0\x10"
+    /* www2 A 192.0.2.1.  */
+    "\x04www2\xc0\x10"
+    "\x00\x01\x00\x01\x00\x00\x00\x00\x00\x04"
+    "\xc0\x00\x02\x01";
+  check_packet (packet, sizeof (packet) - 1, __func__,
+                "name: www.example\n"
+                "name: www1.example\n"
+                "name: www2.example\n"
+                "address: 192.0.2.1\n");
+}
+
+static int
+do_test (void)
+{
+  test_aaaa_length ();
+  test_multiple_cnames ();
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/tst-support_record_failure-2.sh b/support/tst-support_record_failure-2.sh
new file mode 100644
index 0000000..2c9372c
--- /dev/null
+++ b/support/tst-support_record_failure-2.sh
@@ -0,0 +1,69 @@
+#!/bin/sh
+# Test failure recording (with and without --direct).
+# Copyright (C) 2016-2017 Free Software Foundation, Inc.
+# This file is part of the GNU C Library.
+
+# The GNU C Library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# The GNU C Library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with the GNU C Library; if not, see
+# <http://www.gnu.org/licenses/>.  */
+
+set -e
+
+common_objpfx=$1; shift
+test_program_prefix_before_env=$1; shift
+run_program_env=$1; shift
+test_program_prefix_after_env=$1; shift
+
+run_test () {
+    expected_status="$1"
+    expected_output="$2"
+    shift 2
+    args="${common_objpfx}support/tst-support_record_failure $*"
+    echo "running: $args"
+    set +e
+    output="$(${test_program_prefix_before_env} \
+		 ${run_program} ${test_program_prefix_after_env} $args)"
+    status=$?
+    set -e
+    echo "  exit status: $status"
+    if test "$output" != "$expected_output" ; then
+	echo "error: unexpected output: $output"
+	exit 1
+    fi
+    if test "$status" -ne "$expected_status" ; then
+	echo "error: exit status $expected_status expected"
+	exit 1
+    fi
+}
+
+different_status () {
+    direct="$1"
+    run_test 1 "error: 1 test failures" $direct --status=0
+    run_test 1 "error: 1 test failures" $direct --status=1
+    run_test 2 "error: 1 test failures" $direct --status=2
+    run_test 1 "error: 1 test failures" $direct --status=77
+    run_test 2 "error: tst-support_record_failure.c:109: not true: false
+error: 1 test failures" $direct --test-verify
+    run_test 2 "error: tst-support_record_failure.c:109: not true: false
+info: execution passed failed TEST_VERIFY
+error: 1 test failures" $direct --test-verify --verbose
+}
+
+different_status
+different_status --direct
+
+run_test 1 "error: tst-support_record_failure.c:116: not true: false
+error: 1 test failures" --test-verify-exit
+# --direct does not print the summary error message if exit is called.
+run_test 1 "error: tst-support_record_failure.c:116: not true: false" \
+	 --direct --test-verify-exit
diff --git a/support/tst-support_record_failure.c b/support/tst-support_record_failure.c
new file mode 100644
index 0000000..e739e73
--- /dev/null
+++ b/support/tst-support_record_failure.c
@@ -0,0 +1,153 @@
+/* Test support_record_failure state sharing.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/support.h>
+#include <support/test-driver.h>
+#include <support/xunistd.h>
+
+#include <getopt.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+static int exit_status_with_failure = -1;
+static bool test_verify;
+static bool test_verify_exit;
+enum
+  {
+    OPT_STATUS = 10001,
+    OPT_TEST_VERIFY,
+    OPT_TEST_VERIFY_EXIT,
+  };
+#define CMDLINE_OPTIONS                                                 \
+  { "status", required_argument, NULL, OPT_STATUS },                    \
+  { "test-verify", no_argument, NULL, OPT_TEST_VERIFY },                \
+  { "test-verify-exit", no_argument, NULL, OPT_TEST_VERIFY_EXIT },
+static void
+cmdline_process (int c)
+{
+  switch (c)
+    {
+    case OPT_STATUS:
+      exit_status_with_failure = atoi (optarg);
+      break;
+    case OPT_TEST_VERIFY:
+      test_verify = true;
+      break;
+    case OPT_TEST_VERIFY_EXIT:
+      test_verify_exit = true;
+      break;
+    }
+}
+#define CMDLINE_PROCESS cmdline_process
+
+static void
+check_failure_reporting (int phase, int zero, int unsupported)
+{
+  int status = support_report_failure (0);
+  if (status != zero)
+    {
+      printf ("real-error (phase %d): support_report_failure (0) == %d\n",
+              phase, status);
+      exit (1);
+    }
+  status = support_report_failure (1);
+  if (status != 1)
+    {
+      printf ("real-error (phase %d): support_report_failure (1) == %d\n",
+              phase, status);
+      exit (1);
+    }
+  status = support_report_failure (2);
+  if (status != 2)
+    {
+      printf ("real-error (phase %d): support_report_failure (2) == %d\n",
+              phase, status);
+      exit (1);
+    }
+  status = support_report_failure (EXIT_UNSUPPORTED);
+  if (status != unsupported)
+    {
+      printf ("real-error (phase %d): "
+              "support_report_failure (EXIT_UNSUPPORTED) == %d\n",
+              phase, status);
+      exit (1);
+    }
+}
+
+static int
+do_test (void)
+{
+  if (exit_status_with_failure >= 0)
+    {
+      /* External invocation with requested error status.  Used by
+         tst-support_report_failure-2.sh.  */
+      support_record_failure ();
+      return exit_status_with_failure;
+    }
+  TEST_VERIFY (true);
+  TEST_VERIFY_EXIT (true);
+  if (test_verify)
+    {
+      TEST_VERIFY (false);
+      if (test_verbose)
+        printf ("info: execution passed failed TEST_VERIFY\n");
+      return 2; /* Expected exit status.  */
+    }
+  if (test_verify_exit)
+    {
+      TEST_VERIFY_EXIT (false);
+      return 3; /* Not reached.  Expected exit status is 1.  */
+    }
+
+  printf ("info: This test tests the test framework.\n"
+          "info: It reports some expected errors on stdout.\n");
+
+  /* Check that the status is passed through unchanged.  */
+  check_failure_reporting (1, 0, EXIT_UNSUPPORTED);
+
+  /* Check state propagation from a subprocess.  */
+  pid_t pid = xfork ();
+  if (pid == 0)
+    {
+      support_record_failure ();
+      _exit (0);
+    }
+  int status;
+  xwaitpid (pid, &status, 0);
+  if (status != 0)
+    {
+      printf ("real-error: incorrect status from subprocess: %d\n", status);
+      return 1;
+    }
+  check_failure_reporting (2, 1, 1);
+
+  /* Also test directly in the parent process.  */
+  support_record_failure_reset ();
+  check_failure_reporting (3, 0, EXIT_UNSUPPORTED);
+  support_record_failure ();
+  check_failure_reporting (4, 1, 1);
+
+  /* We need to mask the failure above.  */
+  support_record_failure_reset ();
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/support/write_message.c b/support/write_message.c
new file mode 100644
index 0000000..f03ed93
--- /dev/null
+++ b/support/write_message.c
@@ -0,0 +1,29 @@
+/* Write a message to standard output.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <string.h>
+#include <unistd.h>
+
+void
+write_message (const char *message)
+{
+  ssize_t unused __attribute__ ((unused));
+  unused = write (STDOUT_FILENO, message, strlen (message));
+}
diff --git a/support/xaccept.c b/support/xaccept.c
new file mode 100644
index 0000000..7b25af3
--- /dev/null
+++ b/support/xaccept.c
@@ -0,0 +1,32 @@
+/* accept with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+int
+xaccept (int fd, struct sockaddr *sa, socklen_t *salen)
+{
+  int clientfd = accept (fd, sa, salen);
+  if (clientfd < 0)
+    FAIL_EXIT1 ("accept (%d): %m", fd);
+  return clientfd;
+}
diff --git a/support/xaccept4.c b/support/xaccept4.c
new file mode 100644
index 0000000..67dd95e
--- /dev/null
+++ b/support/xaccept4.c
@@ -0,0 +1,32 @@
+/* accept4 with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+int
+xaccept4 (int fd, struct sockaddr *sa, socklen_t *salen, int flags)
+{
+  int clientfd = accept4 (fd, sa, salen, flags);
+  if (clientfd < 0)
+    FAIL_EXIT1 ("accept4 (%d, 0x%x): %m", fd, flags);
+  return clientfd;
+}
diff --git a/support/xasprintf.c b/support/xasprintf.c
new file mode 100644
index 0000000..5157680
--- /dev/null
+++ b/support/xasprintf.c
@@ -0,0 +1,36 @@
+/* Error-checking wrapper for asprintf.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+char *
+xasprintf (const char *format, ...)
+{
+  va_list ap;
+  va_start (ap, format);
+  char *result;
+  if (vasprintf (&result, format, ap) < 0)
+    FAIL_EXIT1 ("asprintf: %m");
+  va_end (ap);
+  return result;
+}
diff --git a/support/xbind.c b/support/xbind.c
new file mode 100644
index 0000000..cfc6dd8
--- /dev/null
+++ b/support/xbind.c
@@ -0,0 +1,30 @@
+/* bind with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xbind (int fd, const struct sockaddr *sa, socklen_t sa_len)
+{
+  if (bind (fd, sa, sa_len) != 0)
+    FAIL_EXIT1 ("bind (%d), family %d: %m", fd, sa->sa_family);
+}
diff --git a/support/xcalloc.c b/support/xcalloc.c
new file mode 100644
index 0000000..135f42d
--- /dev/null
+++ b/support/xcalloc.c
@@ -0,0 +1,34 @@
+/* Error-checking wrapper for calloc.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *
+xcalloc (size_t n, size_t s)
+{
+  void *p;
+
+  p = calloc (n, s);
+  if (p == NULL)
+    oom_error ("calloc", n * s);
+  return p;
+}
diff --git a/support/xchroot.c b/support/xchroot.c
new file mode 100644
index 0000000..abcc299
--- /dev/null
+++ b/support/xchroot.c
@@ -0,0 +1,28 @@
+/* chroot with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/stat.h>
+
+void
+xchroot (const char *path)
+{
+  if (chroot (path) != 0)
+    FAIL_EXIT1 ("chroot (\"%s\"): %m", path);
+}
diff --git a/support/xclose.c b/support/xclose.c
new file mode 100644
index 0000000..c931e08
--- /dev/null
+++ b/support/xclose.c
@@ -0,0 +1,28 @@
+/* close with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+#include <support/check.h>
+#include <errno.h>
+
+void
+xclose (int fd)
+{
+  if (close (fd) < 0 && errno != EINTR)
+    FAIL_EXIT1 ("close of descriptor %d failed: %m", fd);
+}
diff --git a/support/xconnect.c b/support/xconnect.c
new file mode 100644
index 0000000..0266dbc
--- /dev/null
+++ b/support/xconnect.c
@@ -0,0 +1,30 @@
+/* connect with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xconnect (int fd, const struct sockaddr *sa, socklen_t sa_len)
+{
+  if (connect (fd, sa, sa_len) != 0)
+    FAIL_EXIT1 ("connect (%d), family %d: %m", fd, sa->sa_family);
+}
diff --git a/support/xdup2.c b/support/xdup2.c
new file mode 100644
index 0000000..dc08c94
--- /dev/null
+++ b/support/xdup2.c
@@ -0,0 +1,28 @@
+/* dup2 with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+
+#include <support/check.h>
+
+void
+xdup2 (int from, int to)
+{
+  if (dup2 (from, to) < 0)
+    FAIL_EXIT1 ("dup2 (%d, %d): %m", from, to);
+}
diff --git a/support/xfclose.c b/support/xfclose.c
new file mode 100644
index 0000000..2737f05
--- /dev/null
+++ b/support/xfclose.c
@@ -0,0 +1,33 @@
+/* fclose with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xstdio.h>
+
+#include <support/check.h>
+#include <stdlib.h>
+
+void
+xfclose (FILE *fp)
+{
+  if (ferror (fp))
+    FAIL_EXIT1 ("stdio stream closed with pending errors");
+  if (fflush (fp) != 0)
+    FAIL_EXIT1 ("fflush: %m");
+  if (fclose (fp) != 0)
+    FAIL_EXIT1 ("fclose: %m");
+}
diff --git a/support/xfopen.c b/support/xfopen.c
new file mode 100644
index 0000000..14532a0
--- /dev/null
+++ b/support/xfopen.c
@@ -0,0 +1,31 @@
+/* fopen with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xstdio.h>
+
+#include <support/check.h>
+#include <stdlib.h>
+
+FILE *
+xfopen (const char *path, const char *mode)
+{
+  FILE *fp = fopen (path, mode);
+  if (fp == NULL)
+    FAIL_EXIT1 ("could not open %s (mode \"%s\"): %m", path, mode);
+  return fp;
+}
diff --git a/support/xfork.c b/support/xfork.c
new file mode 100644
index 0000000..aa52ba6
--- /dev/null
+++ b/support/xfork.c
@@ -0,0 +1,32 @@
+/* fork with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+pid_t
+xfork (void)
+{
+  pid_t result = fork ();
+  if (result < 0)
+    FAIL_EXIT1 ("fork: %m");
+  return result;
+}
diff --git a/support/xgetsockname.c b/support/xgetsockname.c
new file mode 100644
index 0000000..c3bd884
--- /dev/null
+++ b/support/xgetsockname.c
@@ -0,0 +1,30 @@
+/* getsockname with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xgetsockname (int fd, struct sockaddr *sa, socklen_t *plen)
+{
+  if (getsockname (fd, sa, plen) != 0)
+    FAIL_EXIT1 ("setsockopt (%d): %m", fd);
+}
diff --git a/support/xlisten.c b/support/xlisten.c
new file mode 100644
index 0000000..1953e59
--- /dev/null
+++ b/support/xlisten.c
@@ -0,0 +1,30 @@
+/* listen with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xlisten (int fd, int backlog)
+{
+  if (listen (fd, backlog) != 0)
+    FAIL_EXIT1 ("listen (%d, %d): %m", fd, backlog);
+}
diff --git a/support/xmalloc.c b/support/xmalloc.c
new file mode 100644
index 0000000..450f699
--- /dev/null
+++ b/support/xmalloc.c
@@ -0,0 +1,34 @@
+/* Error-checking wrapper for malloc.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *
+xmalloc (size_t n)
+{
+  void *p;
+
+  p = malloc (n);
+  if (p == NULL)
+    oom_error ("malloc", n);
+  return p;
+}
diff --git a/support/xmemstream.c b/support/xmemstream.c
new file mode 100644
index 0000000..bce6dc9
--- /dev/null
+++ b/support/xmemstream.c
@@ -0,0 +1,42 @@
+/* Error-checking wrappers for memstream functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xmemstream.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+void
+xopen_memstream (struct xmemstream *stream)
+{
+  int old_errno = errno;
+  *stream = (struct xmemstream) {};
+  stream->out = open_memstream (&stream->buffer, &stream->length);
+  if (stream->out == NULL)
+    FAIL_EXIT1 ("open_memstream: %m");
+  errno = old_errno;
+}
+
+void
+xfclose_memstream (struct xmemstream *stream)
+{
+  xfclose (stream->out);
+  stream->out = NULL;
+}
diff --git a/support/xmemstream.h b/support/xmemstream.h
new file mode 100644
index 0000000..e5ba231
--- /dev/null
+++ b/support/xmemstream.h
@@ -0,0 +1,49 @@
+/* Error-checking wrappers for memstream functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_XMEMSTREAM_H
+#define SUPPORT_XMEMSTREAM_H
+
+#include <stdio.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Wrappers for other libc functions.  */
+struct xmemstream
+{
+  FILE *out;
+  char *buffer;
+  size_t length;
+};
+
+/* Create a new in-memory stream.  Initializes *STREAM.  After this
+   function returns, STREAM->out is a file descriptor open for
+   writing.  errno is preserved, so that the %m format specifier can
+   be used for writing to STREAM->out.  */
+void xopen_memstream (struct xmemstream *stream);
+
+/* Closes STREAM->OUT.  After this function returns, STREAM->buffer
+   and STREAM->length denote a memory range which contains the bytes
+   written to the output stream.  The caller should free
+   STREAM->buffer.  */
+void xfclose_memstream (struct xmemstream *stream);
+
+__END_DECLS
+
+#endif /* SUPPORT_XMEMSTREAM_H */
diff --git a/support/xmkdir.c b/support/xmkdir.c
new file mode 100644
index 0000000..ea17d49
--- /dev/null
+++ b/support/xmkdir.c
@@ -0,0 +1,28 @@
+/* mkdir with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/stat.h>
+
+void
+xmkdir (const char *path, mode_t mode)
+{
+  if (mkdir (path, mode) != 0)
+    FAIL_EXIT1 ("mkdir (\"%s\", 0%o): %m", path, mode);
+}
diff --git a/support/xmmap.c b/support/xmmap.c
new file mode 100644
index 0000000..435b1eb
--- /dev/null
+++ b/support/xmmap.c
@@ -0,0 +1,31 @@
+/* mmap with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+
+void *
+xmmap (void *addr, size_t length, int prot, int flags, int fd)
+{
+  void *result = mmap (addr, length, prot, flags, fd, 0);
+  if (result == MAP_FAILED)
+    FAIL_EXIT1 ("mmap of %zu bytes, prot=0x%x, flags=0x%x: %m",
+                length, prot, flags);
+  return result;
+}
diff --git a/support/xmunmap.c b/support/xmunmap.c
new file mode 100644
index 0000000..6ef5a4a
--- /dev/null
+++ b/support/xmunmap.c
@@ -0,0 +1,28 @@
+/* munmap with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <sys/mman.h>
+
+void
+xmunmap (void *addr, size_t length)
+{
+  if (munmap (addr, length) != 0)
+    FAIL_EXIT1 ("munmap of %zu bytes: %m", length);
+}
diff --git a/support/xopen.c b/support/xopen.c
new file mode 100644
index 0000000..7f033a0
--- /dev/null
+++ b/support/xopen.c
@@ -0,0 +1,30 @@
+/* open64 with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <fcntl.h>
+
+int
+xopen (const char *path, int flags, mode_t mode)
+{
+  int ret = open64 (path, flags, mode);
+  if (ret < 0)
+    FAIL_EXIT1 ("open64 (\"%s\", 0x%x, 0%o): %m", path, flags, mode);
+  return ret;
+}
diff --git a/support/xpipe.c b/support/xpipe.c
new file mode 100644
index 0000000..89a64a5
--- /dev/null
+++ b/support/xpipe.c
@@ -0,0 +1,28 @@
+/* pipe with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+
+#include <support/check.h>
+
+void
+xpipe (int fds[2])
+{
+  if (pipe (fds) < 0)
+    FAIL_EXIT1 ("pipe: %m");
+}
diff --git a/support/xpoll.c b/support/xpoll.c
new file mode 100644
index 0000000..bec2521
--- /dev/null
+++ b/support/xpoll.c
@@ -0,0 +1,32 @@
+/* poll with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+int
+xpoll (struct pollfd *fds, nfds_t nfds, int timeout)
+{
+  int ret = poll (fds, nfds, timeout);
+  if (ret < 0)
+    FAIL_EXIT1 ("poll: %m");
+  return ret;
+}
diff --git a/support/xpthread_attr_destroy.c b/support/xpthread_attr_destroy.c
new file mode 100644
index 0000000..664c809
--- /dev/null
+++ b/support/xpthread_attr_destroy.c
@@ -0,0 +1,26 @@
+/* pthread_attr_destroy with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_destroy (pthread_attr_t *attr)
+{
+  xpthread_check_return ("pthread_attr_destroy",
+			 pthread_attr_destroy (attr));
+}
diff --git a/support/xpthread_attr_init.c b/support/xpthread_attr_init.c
new file mode 100644
index 0000000..2e30ade
--- /dev/null
+++ b/support/xpthread_attr_init.c
@@ -0,0 +1,25 @@
+/* pthread_attr_init with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_init (pthread_attr_t *attr)
+{
+  xpthread_check_return ("pthread_attr_init", pthread_attr_init (attr));
+}
diff --git a/support/xpthread_attr_setdetachstate.c b/support/xpthread_attr_setdetachstate.c
new file mode 100644
index 0000000..b544dba
--- /dev/null
+++ b/support/xpthread_attr_setdetachstate.c
@@ -0,0 +1,27 @@
+/* pthread_attr_setdetachstate with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_setdetachstate (pthread_attr_t *attr, int detachstate)
+{
+  xpthread_check_return ("pthread_attr_setdetachstate",
+			 pthread_attr_setdetachstate (attr,
+						      detachstate));
+}
diff --git a/support/xpthread_attr_setstacksize.c b/support/xpthread_attr_setstacksize.c
new file mode 100644
index 0000000..02d0631
--- /dev/null
+++ b/support/xpthread_attr_setstacksize.c
@@ -0,0 +1,26 @@
+/* pthread_attr_setstacksize with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_attr_setstacksize (pthread_attr_t *attr, size_t stacksize)
+{
+  xpthread_check_return ("pthread_attr_setstacksize",
+			 pthread_attr_setstacksize (attr, stacksize));
+}
diff --git a/support/xpthread_barrier_destroy.c b/support/xpthread_barrier_destroy.c
new file mode 100644
index 0000000..efc0719
--- /dev/null
+++ b/support/xpthread_barrier_destroy.c
@@ -0,0 +1,26 @@
+/* pthread_barrier_destroy with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_barrier_destroy (pthread_barrier_t *barrier)
+{
+  xpthread_check_return ("pthread_barrier_destroy",
+                         pthread_barrier_destroy (barrier));
+}
diff --git a/support/xpthread_barrier_init.c b/support/xpthread_barrier_init.c
new file mode 100644
index 0000000..b32dad1
--- /dev/null
+++ b/support/xpthread_barrier_init.c
@@ -0,0 +1,27 @@
+/* pthread_barrier_init with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_barrier_init (pthread_barrier_t *barrier,
+                       pthread_barrierattr_t *attr, unsigned int count)
+{
+  xpthread_check_return ("pthread_barrier_init",
+                         pthread_barrier_init (barrier, attr, count));
+}
diff --git a/support/xpthread_barrier_wait.c b/support/xpthread_barrier_wait.c
new file mode 100644
index 0000000..7cee44d
--- /dev/null
+++ b/support/xpthread_barrier_wait.c
@@ -0,0 +1,28 @@
+/* pthread_barrier_wait with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+int
+xpthread_barrier_wait (pthread_barrier_t *barrier)
+{
+  int ret = pthread_barrier_wait (barrier);
+  if (ret != 0 && ret != PTHREAD_BARRIER_SERIAL_THREAD)
+    xpthread_check_return ("pthread_barrier_wait", ret);
+  return ret == PTHREAD_BARRIER_SERIAL_THREAD;
+}
diff --git a/support/xpthread_cancel.c b/support/xpthread_cancel.c
new file mode 100644
index 0000000..3af16f9
--- /dev/null
+++ b/support/xpthread_cancel.c
@@ -0,0 +1,25 @@
+/* pthread_cancel with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_cancel (pthread_t thr)
+{
+  xpthread_check_return ("pthread_cancel", pthread_cancel (thr));
+}
diff --git a/support/xpthread_check_return.c b/support/xpthread_check_return.c
new file mode 100644
index 0000000..3094d82
--- /dev/null
+++ b/support/xpthread_check_return.c
@@ -0,0 +1,34 @@
+/* Return value checking for pthread functions, exit variant.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xpthread_check_return (const char *function, int value)
+{
+  if (value != 0)
+    {
+      errno = value;
+      FAIL_EXIT1 ("%s: %m", function);
+    }
+}
diff --git a/support/xpthread_cond_wait.c b/support/xpthread_cond_wait.c
new file mode 100644
index 0000000..b0e9b2a
--- /dev/null
+++ b/support/xpthread_cond_wait.c
@@ -0,0 +1,26 @@
+/* pthread_cond_wait with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_cond_wait (pthread_cond_t *cond, pthread_mutex_t *mutex)
+{
+  xpthread_check_return
+    ("pthread_cond_wait", pthread_cond_wait (cond, mutex));
+}
diff --git a/support/xpthread_create.c b/support/xpthread_create.c
new file mode 100644
index 0000000..98c63e5
--- /dev/null
+++ b/support/xpthread_create.c
@@ -0,0 +1,29 @@
+/* pthread_create with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+pthread_t
+xpthread_create (pthread_attr_t *attr,
+                 void *(*thread_func) (void *), void *closure)
+{
+  pthread_t thr;
+  xpthread_check_return
+    ("pthread_create", pthread_create (&thr, attr, thread_func, closure));
+  return thr;
+}
diff --git a/support/xpthread_detach.c b/support/xpthread_detach.c
new file mode 100644
index 0000000..2088af2
--- /dev/null
+++ b/support/xpthread_detach.c
@@ -0,0 +1,25 @@
+/* pthread_detach with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_detach (pthread_t thr)
+{
+  xpthread_check_return ("pthread_detach", pthread_detach (thr));
+}
diff --git a/support/xpthread_join.c b/support/xpthread_join.c
new file mode 100644
index 0000000..f23bb9a
--- /dev/null
+++ b/support/xpthread_join.c
@@ -0,0 +1,27 @@
+/* pthread_join with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void *
+xpthread_join (pthread_t thr)
+{
+  void *result;
+  xpthread_check_return ("pthread_join", pthread_join (thr, &result));
+  return result;
+}
diff --git a/support/xpthread_mutex_consistent.c b/support/xpthread_mutex_consistent.c
new file mode 100644
index 0000000..52364be
--- /dev/null
+++ b/support/xpthread_mutex_consistent.c
@@ -0,0 +1,26 @@
+/* pthread_mutex_consistent with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutex_consistent (pthread_mutex_t *mutex)
+{
+  xpthread_check_return ("pthread_mutex_consistent",
+                         pthread_mutex_consistent (mutex));
+}
diff --git a/support/xpthread_mutex_destroy.c b/support/xpthread_mutex_destroy.c
new file mode 100644
index 0000000..f11f8f0
--- /dev/null
+++ b/support/xpthread_mutex_destroy.c
@@ -0,0 +1,26 @@
+/* pthread_mutex_destroy with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutex_destroy (pthread_mutex_t *mutex)
+{
+  xpthread_check_return ("pthread_mutex_destroy",
+                         pthread_mutex_destroy (mutex));
+}
diff --git a/support/xpthread_mutex_init.c b/support/xpthread_mutex_init.c
new file mode 100644
index 0000000..2d16d1b
--- /dev/null
+++ b/support/xpthread_mutex_init.c
@@ -0,0 +1,26 @@
+/* pthread_mutex_init with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutex_init (pthread_mutex_t *mutex, const pthread_mutexattr_t *attr)
+{
+  xpthread_check_return ("pthread_mutex_init",
+                         pthread_mutex_init (mutex, attr));
+}
diff --git a/support/xpthread_mutex_lock.c b/support/xpthread_mutex_lock.c
new file mode 100644
index 0000000..af727b4
--- /dev/null
+++ b/support/xpthread_mutex_lock.c
@@ -0,0 +1,25 @@
+/* pthread_mutex_lock with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutex_lock (pthread_mutex_t *mutex)
+{
+  xpthread_check_return ("pthread_mutex_lock", pthread_mutex_lock (mutex));
+}
diff --git a/support/xpthread_mutex_unlock.c b/support/xpthread_mutex_unlock.c
new file mode 100644
index 0000000..161b41e
--- /dev/null
+++ b/support/xpthread_mutex_unlock.c
@@ -0,0 +1,25 @@
+/* pthread_mutex_unlock with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutex_unlock (pthread_mutex_t *mutex)
+{
+  xpthread_check_return ("pthread_mutex_unlock", pthread_mutex_unlock (mutex));
+}
diff --git a/support/xpthread_mutexattr_destroy.c b/support/xpthread_mutexattr_destroy.c
new file mode 100644
index 0000000..c699e32
--- /dev/null
+++ b/support/xpthread_mutexattr_destroy.c
@@ -0,0 +1,26 @@
+/* pthread_mutexattr_destroy with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_destroy (pthread_mutexattr_t *attr)
+{
+  xpthread_check_return ("pthread_mutexattr_destroy",
+                         pthread_mutexattr_destroy (attr));
+}
diff --git a/support/xpthread_mutexattr_init.c b/support/xpthread_mutexattr_init.c
new file mode 100644
index 0000000..fa93fab
--- /dev/null
+++ b/support/xpthread_mutexattr_init.c
@@ -0,0 +1,25 @@
+/* pthread_mutexattr_init with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_init (pthread_mutexattr_t *attr)
+{
+  xpthread_check_return ("pthread_mutexattr_init", pthread_mutexattr_init (attr));
+}
diff --git a/support/xpthread_mutexattr_setprotocol.c b/support/xpthread_mutexattr_setprotocol.c
new file mode 100644
index 0000000..353f75e
--- /dev/null
+++ b/support/xpthread_mutexattr_setprotocol.c
@@ -0,0 +1,26 @@
+/* pthread_mutexattr_setprotocol with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_setprotocol (pthread_mutexattr_t *attr, int flag)
+{
+  xpthread_check_return ("pthread_mutexattr_setprotocol",
+                         pthread_mutexattr_setprotocol (attr, flag));
+}
diff --git a/support/xpthread_mutexattr_setpshared.c b/support/xpthread_mutexattr_setpshared.c
new file mode 100644
index 0000000..242da1a
--- /dev/null
+++ b/support/xpthread_mutexattr_setpshared.c
@@ -0,0 +1,26 @@
+/* pthread_mutexattr_setpshared with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_setpshared (pthread_mutexattr_t *attr, int flag)
+{
+  xpthread_check_return ("pthread_mutexattr_setpshared",
+                         pthread_mutexattr_setpshared (attr, flag));
+}
diff --git a/support/xpthread_mutexattr_setrobust.c b/support/xpthread_mutexattr_setrobust.c
new file mode 100644
index 0000000..d7d6fa8
--- /dev/null
+++ b/support/xpthread_mutexattr_setrobust.c
@@ -0,0 +1,26 @@
+/* pthread_mutexattr_setrobust with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_setrobust (pthread_mutexattr_t *attr, int flag)
+{
+  xpthread_check_return ("pthread_mutexattr_setrobust",
+                         pthread_mutexattr_setrobust (attr, flag));
+}
diff --git a/support/xpthread_mutexattr_settype.c b/support/xpthread_mutexattr_settype.c
new file mode 100644
index 0000000..cf22170
--- /dev/null
+++ b/support/xpthread_mutexattr_settype.c
@@ -0,0 +1,26 @@
+/* pthread_mutexattr_settype with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_mutexattr_settype (pthread_mutexattr_t *attr, int flag)
+{
+  xpthread_check_return ("pthread_mutexattr_settype",
+                         pthread_mutexattr_settype (attr, flag));
+}
diff --git a/support/xpthread_once.c b/support/xpthread_once.c
new file mode 100644
index 0000000..70d58db
--- /dev/null
+++ b/support/xpthread_once.c
@@ -0,0 +1,25 @@
+/* pthread_once with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_once (pthread_once_t *guard, void (*func) (void))
+{
+  xpthread_check_return ("pthread_once", pthread_once (guard, func));
+}
diff --git a/support/xpthread_sigmask.c b/support/xpthread_sigmask.c
new file mode 100644
index 0000000..0ba9ca0
--- /dev/null
+++ b/support/xpthread_sigmask.c
@@ -0,0 +1,34 @@
+/* pthread_sigmask with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsignal.h>
+#include <support/support.h>
+
+#include <unistd.h>
+
+void
+xpthread_sigmask (int how, const sigset_t *set, sigset_t *oldset)
+{
+  if (pthread_sigmask (how, set, oldset) != 0)
+    {
+      write_message ("error: pthread_setmask failed\n");
+      /* Do not use exit because pthread_sigmask can be called from a
+         signal handler.  */
+      _exit (1);
+    }
+}
diff --git a/support/xpthread_spin_lock.c b/support/xpthread_spin_lock.c
new file mode 100644
index 0000000..6975215
--- /dev/null
+++ b/support/xpthread_spin_lock.c
@@ -0,0 +1,25 @@
+/* pthread_spin_lock with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_spin_lock (pthread_spinlock_t *lock)
+{
+  xpthread_check_return ("pthread_spin_lock", pthread_spin_lock (lock));
+}
diff --git a/support/xpthread_spin_unlock.c b/support/xpthread_spin_unlock.c
new file mode 100644
index 0000000..4f19a44
--- /dev/null
+++ b/support/xpthread_spin_unlock.c
@@ -0,0 +1,25 @@
+/* pthread_spin_unlock with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+
+void
+xpthread_spin_unlock (pthread_spinlock_t *lock)
+{
+  xpthread_check_return ("pthread_spin_unlock", pthread_spin_unlock (lock));
+}
diff --git a/support/xrealloc.c b/support/xrealloc.c
new file mode 100644
index 0000000..00c3138
--- /dev/null
+++ b/support/xrealloc.c
@@ -0,0 +1,32 @@
+/* Error-checking wrapper for realloc.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void *
+xrealloc (void *p, size_t n)
+{
+  void *result = realloc (p, n);
+  if (result == NULL && (n > 0 || p == NULL))
+    oom_error ("realloc", n);
+  return result;
+}
diff --git a/support/xrecvfrom.c b/support/xrecvfrom.c
new file mode 100644
index 0000000..17809c4
--- /dev/null
+++ b/support/xrecvfrom.c
@@ -0,0 +1,33 @@
+/* recvfrom with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+size_t
+xrecvfrom (int fd, void *buf, size_t buflen, int flags,
+           struct sockaddr *sa, socklen_t *salen)
+{
+  ssize_t ret = recvfrom (fd, buf, buflen, flags, sa, salen);
+  if (ret < 0)
+    FAIL_EXIT1 ("error: recvfrom (%d), %zu bytes buffer: %m", fd, buflen);
+  return ret;
+}
diff --git a/support/xsendto.c b/support/xsendto.c
new file mode 100644
index 0000000..20bddf6
--- /dev/null
+++ b/support/xsendto.c
@@ -0,0 +1,35 @@
+/* sendto with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xsendto (int fd, const void *buf, size_t buflen, int flags,
+         const struct sockaddr *sa, socklen_t salen)
+{
+  ssize_t ret = sendto (fd, buf, buflen, flags, sa, salen);
+  if (ret < 0)
+    FAIL_EXIT1 ("sendto (%d), %zu bytes, family %d: %m",
+                fd, buflen, sa->sa_family);
+  if (ret != buflen)
+    FAIL_EXIT1 ("sendto (%d) sent %zd bytes instead of %zu", fd, ret, buflen);
+}
diff --git a/support/xsetsockopt.c b/support/xsetsockopt.c
new file mode 100644
index 0000000..9931882
--- /dev/null
+++ b/support/xsetsockopt.c
@@ -0,0 +1,31 @@
+/* setsockopt with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+void
+xsetsockopt (int fd, int level, int name, const void *val, socklen_t vallen)
+{
+  if (setsockopt (fd, level, name, val, vallen) != 0)
+    FAIL_EXIT1 ("setsockopt (%d, %d, %d), %zu bytes: %m",
+                fd, level, name, (size_t) vallen);
+}
diff --git a/support/xsignal.h b/support/xsignal.h
new file mode 100644
index 0000000..3dc0d9d
--- /dev/null
+++ b/support/xsignal.h
@@ -0,0 +1,34 @@
+/* Support functionality for using signals.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_SIGNAL_H
+#define SUPPORT_SIGNAL_H
+
+#include <signal.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* The following functions call the corresponding libpthread functions
+   and terminate the process on error.  */
+
+void xpthread_sigmask (int how, const sigset_t *set, sigset_t *oldset);
+
+__END_DECLS
+
+#endif /* SUPPORT_SIGNAL_H */
diff --git a/support/xsocket.c b/support/xsocket.c
new file mode 100644
index 0000000..c1deaee
--- /dev/null
+++ b/support/xsocket.c
@@ -0,0 +1,32 @@
+/* socket with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xsocket.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+
+int
+xsocket (int domain, int type, int protocol)
+{
+  int fd = socket (domain, type, protocol);
+  if (fd < 0)
+    FAIL_EXIT1 ("socket (%d, %d, %d): %m\n", domain, type, protocol);
+  return fd;
+}
diff --git a/support/xsocket.h b/support/xsocket.h
new file mode 100644
index 0000000..d672494
--- /dev/null
+++ b/support/xsocket.h
@@ -0,0 +1,39 @@
+/* Error-checking wrappers for socket functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_XSOCKET_H
+#define SUPPORT_XSOCKET_H
+
+#include <poll.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+int xsocket (int, int, int);
+void xsetsockopt (int, int, int, const void *, socklen_t);
+void xgetsockname (int, struct sockaddr *, socklen_t *);
+void xconnect (int, const struct sockaddr *, socklen_t);
+void xbind (int, const struct sockaddr *, socklen_t);
+void xlisten (int, int);
+int xaccept (int, struct sockaddr *, socklen_t *);
+int xaccept4 (int, struct sockaddr *, socklen_t *, int);
+void xsendto (int, const void *, size_t, int,
+              const struct sockaddr *, socklen_t);
+size_t xrecvfrom (int, void *, size_t, int, struct sockaddr *, socklen_t *);
+int xpoll (struct pollfd *, nfds_t, int);
+
+#endif /* SUPPORT_XSOCKET_H */
diff --git a/support/xstdio.h b/support/xstdio.h
new file mode 100644
index 0000000..bcc2e86
--- /dev/null
+++ b/support/xstdio.h
@@ -0,0 +1,32 @@
+/* Error-checking wrappers for stdio functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_XSTDIO_H
+#define SUPPORT_XSTDIO_H
+
+#include <stdio.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+FILE *xfopen (const char *path, const char *mode);
+void xfclose (FILE *);
+
+__END_DECLS
+
+#endif /* SUPPORT_XSTDIO_H */
diff --git a/support/xstrdup.c b/support/xstrdup.c
new file mode 100644
index 0000000..d6a8c04
--- /dev/null
+++ b/support/xstrdup.c
@@ -0,0 +1,30 @@
+/* strdup with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/support.h>
+
+#include <string.h>
+
+char *
+xstrdup (const char *s)
+{
+  char *p = strdup (s);
+  if (p == NULL)
+    oom_error ("strdup", strlen (s));
+  return p;
+}
diff --git a/support/xthread.h b/support/xthread.h
new file mode 100644
index 0000000..6dd7e70
--- /dev/null
+++ b/support/xthread.h
@@ -0,0 +1,77 @@
+/* Support functionality for using threads.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef SUPPORT_THREAD_H
+#define SUPPORT_THREAD_H
+
+#include <pthread.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+/* Terminate the process (with exit status 0) after SECONDS have
+   elapsed, from a helper thread.  The process is terminated with the
+   exit function, so atexit handlers are executed.  */
+void delayed_exit (int seconds);
+
+/* Terminate the process (with exit status 1) if VALUE is not zero.
+   In that case, print a failure message to standard output mentioning
+   FUNCTION.  The process is terminated with the exit function, so
+   atexit handlers are executed.  */
+void xpthread_check_return (const char *function, int value);
+
+/* The following functions call the corresponding libpthread functions
+   and terminate the process on error.  */
+
+void xpthread_barrier_init (pthread_barrier_t *barrier,
+                            pthread_barrierattr_t *attr, unsigned int count);
+void xpthread_barrier_destroy (pthread_barrier_t *barrier);
+void xpthread_mutexattr_destroy (pthread_mutexattr_t *);
+void xpthread_mutexattr_init (pthread_mutexattr_t *);
+void xpthread_mutexattr_setprotocol (pthread_mutexattr_t *, int);
+void xpthread_mutexattr_setpshared (pthread_mutexattr_t *, int);
+void xpthread_mutexattr_setrobust (pthread_mutexattr_t *, int);
+void xpthread_mutexattr_settype (pthread_mutexattr_t *, int);
+void xpthread_mutex_init (pthread_mutex_t *, const pthread_mutexattr_t *);
+void xpthread_mutex_destroy (pthread_mutex_t *);
+void xpthread_mutex_lock (pthread_mutex_t *mutex);
+void xpthread_mutex_unlock (pthread_mutex_t *mutex);
+void xpthread_mutex_consistent (pthread_mutex_t *);
+void xpthread_spin_lock (pthread_spinlock_t *lock);
+void xpthread_spin_unlock (pthread_spinlock_t *lock);
+void xpthread_cond_wait (pthread_cond_t * cond, pthread_mutex_t * mutex);
+pthread_t xpthread_create (pthread_attr_t *attr,
+                           void *(*thread_func) (void *), void *closure);
+void xpthread_detach (pthread_t thr);
+void xpthread_cancel (pthread_t thr);
+void *xpthread_join (pthread_t thr);
+void xpthread_once (pthread_once_t *guard, void (*func) (void));
+void xpthread_attr_destroy (pthread_attr_t *attr);
+void xpthread_attr_init (pthread_attr_t *attr);
+void xpthread_attr_setdetachstate (pthread_attr_t *attr,
+				   int detachstate);
+void xpthread_attr_setstacksize (pthread_attr_t *attr,
+				 size_t stacksize);
+
+/* This function returns non-zero if pthread_barrier_wait returned
+   PTHREAD_BARRIER_SERIAL_THREAD.  */
+int xpthread_barrier_wait (pthread_barrier_t *barrier);
+
+__END_DECLS
+
+#endif /* SUPPORT_THREAD_H */
diff --git a/support/xunistd.h b/support/xunistd.h
new file mode 100644
index 0000000..151d743
--- /dev/null
+++ b/support/xunistd.h
@@ -0,0 +1,56 @@
+/* POSIX-specific extra functions.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+/* These wrapper functions use POSIX types and therefore cannot be
+   declared in <support/support.h>.  */
+
+#ifndef SUPPORT_XUNISTD_H
+#define SUPPORT_XUNISTD_H
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+__BEGIN_DECLS
+
+struct stat64;
+
+pid_t xfork (void);
+pid_t xwaitpid (pid_t, int *status, int flags);
+void xpipe (int[2]);
+void xdup2 (int, int);
+int xopen (const char *path, int flags, mode_t);
+void xstat (const char *path, struct stat64 *);
+void xmkdir (const char *path, mode_t);
+void xchroot (const char *path);
+
+/* Close the file descriptor.  Ignore EINTR errors, but terminate the
+   process on other errors.  */
+void xclose (int);
+
+/* Write the buffer.  Retry on short writes.  */
+void xwrite (int, const void *, size_t);
+
+/* Invoke mmap with a zero file offset.  */
+void *xmmap (void *addr, size_t length, int prot, int flags, int fd);
+
+void xmunmap (void *addr, size_t length);
+
+__END_DECLS
+
+#endif /* SUPPORT_XUNISTD_H */
diff --git a/support/xwaitpid.c b/support/xwaitpid.c
new file mode 100644
index 0000000..204795e
--- /dev/null
+++ b/support/xwaitpid.c
@@ -0,0 +1,33 @@
+/* waitpid with error checking.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <sys/wait.h>
+
+int
+xwaitpid (int pid, int *status, int flags)
+{
+  pid_t result = waitpid (pid, status, flags);
+  if (result < 0)
+    FAIL_EXIT1 ("waitpid: %m\n");
+  return result;
+}
diff --git a/support/xwrite.c b/support/xwrite.c
new file mode 100644
index 0000000..134e8ee
--- /dev/null
+++ b/support/xwrite.c
@@ -0,0 +1,39 @@
+/* write with error checking and retries.
+   Copyright (C) 2016-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+
+#include <support/check.h>
+
+void
+xwrite (int fd, const void *buffer, size_t length)
+{
+  const char *p = buffer;
+  const char *end = p + length;
+  while (p < end)
+    {
+      ssize_t ret = write (fd, p, end - p);
+      if (ret < 0)
+        FAIL_EXIT1 ("write of %zu bytes failed after %td: %m",
+                    length, p - (const char *) buffer);
+      if (ret == 0)
+        FAIL_EXIT1 ("write return 0 after writing %td bytes of %zu",
+                    p - (const char *) buffer, length);
+      p += ret;
+    }
+}

-----------------------------------------------------------------------


hooks/post-receive
-- 
GNU C Library master sources


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