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[COMMITTED PATCH 1/3] Clean up NPTL fork to be compat-only.
- From: Roland McGrath <roland at hack dot frob dot com>
- To: "GNU C. Library" <libc-alpha at sourceware dot org>
- Date: Fri, 6 Feb 2015 12:18:43 -0800 (PST)
- Subject: [COMMITTED PATCH 1/3] Clean up NPTL fork to be compat-only.
- Authentication-results: sourceware.org; auth=none
I don't know if there was a historical reason for libpthread to have a
fork wrapper, but there is certainly none in the current code. This
change makes it compat-only. It's similar to what I did for vfork,
but simpler for the no-IFUNC case since it doesn't matter whether the
tail call is proper or not.
Tested x86_64-linux-gnu.
Thanks,
Roland
* nptl/pt-fork.c: Rewritten. Put everything under
[SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)].
Use IFUNC to redirect when possible.
* nptl/Versions (libpthread: GLIBC_2.22): New (empty) version set.
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -266,6 +266,9 @@ libpthread {
GLIBC_2.20 {
}
+ GLIBC_2.22 {
+ }
+
GLIBC_PRIVATE {
__pthread_initialize_minimal;
__pthread_clock_gettime; __pthread_clock_settime;
--- a/nptl/pt-fork.c
+++ b/nptl/pt-fork.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2002-2015 Free Software Foundation, Inc.
+/* ABI compatibility for 'fork' symbol in libpthread ABI.
+ Copyright (C) 2002-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
@@ -17,11 +18,55 @@
<http://www.gnu.org/licenses/>. */
#include <unistd.h>
+#include <shlib-compat.h>
+/* libpthread once had its own fork, though there was no apparent reason
+ for it. There is no use in having a separate symbol in libpthread, but
+ the historical ABI requires it. For static linking, there is no need to
+ provide anything here--the libc version will be linked in. For shared
+ library ABI compatibility, there must be __fork and fork symbols in
+ libpthread.so; so we define them using IFUNC to redirect to the libc
+ function. */
-pid_t
-__fork (void)
+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
+
+# if HAVE_IFUNC
+
+static __typeof (fork) *
+__attribute__ ((used))
+fork_resolve (void)
+{
+ return &__libc_fork;
+}
+
+# ifdef HAVE_ASM_SET_DIRECTIVE
+# define DEFINE_FORK(name) \
+ asm (".set " #name ", fork_resolve\n" \
+ ".globl " #name "\n" \
+ ".type " #name ", %gnu_indirect_function");
+# else
+# define DEFINE_FORK(name) \
+ asm (#name " = fork_resolve\n" \
+ ".globl " #name "\n" \
+ ".type " #name ", %gnu_indirect_function");
+# endif
+
+# else /* !HAVE_IFUNC */
+
+static pid_t __attribute__ ((used))
+fork_compat (void)
{
return __libc_fork ();
}
-strong_alias (__fork, fork)
+
+# define DEFINE_FORK(name) strong_alias (fork_compat, name)
+
+# endif /* HAVE_IFUNC */
+
+DEFINE_FORK (fork_ifunc)
+compat_symbol (libpthread, fork_ifunc, fork, GLIBC_2_0);
+
+DEFINE_FORK (__fork_ifunc)
+compat_symbol (libpthread, __fork_ifunc, __fork, GLIBC_2_0);
+
+#endif