[PATCH] malloc: Remove malloc_get_state, malloc_set_state

[fweimer at redhat dot com (Florian Weimer)]

After the removal of __malloc_initialize_hook, newly compiled
Emacs binaries are no longer able to use these interfaces.
malloc_get_state is only used during the Emacs build process,
so we provide a stub implementation only.  Existing Emacs binaries
will not call this stub function, but still reference the symbol.

2016-06-10  Florian Weimer  <fweimer@redhat.com>

	* malloc/malloc.h (malloc_get_state, malloc_set_state): Remove.
	* malloc/malloc.c (malloc_get_state, malloc_set_state): Remove
	weak aliases.
	* malloc/hooks.c (malloc_get_state): New stub implementation as
	compatibility symbo.
	(__malloc_get_state): Remove.
	(malloc_set_state): Rename from __malloc_set_state.  Turn into
	compat symbol.
	* malloc/Makefile (tests): Remove tst-mallocstate.
	* malloc/tst-mallocstate.c: Remove file.

diff --git a/NEWS b/NEWS
index 9d6ac56..de2af85 100644
--- a/NEWS
+++ b/NEWS
@@ -36,6 +36,13 @@ Version 2.24
 * The deprecated __malloc_initialize_hook variable has been removed from the
   API.
 
+* The __malloc_get_state and __malloc_set_state functions have been removed
+  from the API.  __malloc_get_state has been replaced with a stub
+  implementation.  Existing undumped Emacs binaries will have to be
+  recompiled so that they do not use glibc malloc (or malloc heap dumping).
+  Existing installed Emacs binaries (after dumping) are not affected by this
+  change.
+
 Security related changes:
 
 * An unnecessary stack copy in _nss_dns_getnetbyname_r was removed.  It
diff --git a/malloc/Makefile b/malloc/Makefile
index 91eb17d..8473f74 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -25,7 +25,7 @@ include ../Makeconfig
 dist-headers := malloc.h
 headers := $(dist-headers) obstack.h mcheck.h
 tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
-	 tst-mallocstate tst-mcheck tst-mallocfork tst-trim1 \
+	 tst-mcheck tst-mallocfork tst-trim1 \
 	 tst-malloc-usable tst-realloc tst-posix_memalign \
 	 tst-pvalloc tst-memalign tst-mallopt tst-scratch_buffer \
 	 tst-malloc-backtrace tst-malloc-thread-exit \
diff --git a/malloc/hooks.c b/malloc/hooks.c
index caa1e70..8ef2eba 100644
--- a/malloc/hooks.c
+++ b/malloc/hooks.c
@@ -447,6 +447,7 @@ memalign_check (size_t alignment, size_t bytes, const void *caller)
   return mem2mem_check (mem, bytes);
 }
 
+#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_24)
 
 /* Get/set state: malloc_get_state() records the current state of all
    malloc variables (_except_ for the actual heap contents and `hook'
@@ -492,60 +493,20 @@ struct malloc_save_state
   unsigned long narenas;
 };
 
+/* Dummy implementation which always fails.  We need to provide this
+   symbol so that existing Emacs binaries continue to work with
+   BIND_NOW.  */
 void *
-__malloc_get_state (void)
+attribute_compat_text_section
+malloc_get_state (void)
 {
-  struct malloc_save_state *ms;
-  int i;
-  mbinptr b;
-
-  ms = (struct malloc_save_state *) __libc_malloc (sizeof (*ms));
-  if (!ms)
-    return 0;
-
-  (void) mutex_lock (&main_arena.mutex);
-  malloc_consolidate (&main_arena);
-  ms->magic = MALLOC_STATE_MAGIC;
-  ms->version = MALLOC_STATE_VERSION;
-  ms->av[0] = 0;
-  ms->av[1] = 0; /* used to be binblocks, now no longer used */
-  ms->av[2] = top (&main_arena);
-  ms->av[3] = 0; /* used to be undefined */
-  for (i = 1; i < NBINS; i++)
-    {
-      b = bin_at (&main_arena, i);
-      if (first (b) == b)
-        ms->av[2 * i + 2] = ms->av[2 * i + 3] = 0; /* empty bin */
-      else
-        {
-          ms->av[2 * i + 2] = first (b);
-          ms->av[2 * i + 3] = last (b);
-        }
-    }
-  ms->sbrk_base = mp_.sbrk_base;
-  ms->sbrked_mem_bytes = main_arena.system_mem;
-  ms->trim_threshold = mp_.trim_threshold;
-  ms->top_pad = mp_.top_pad;
-  ms->n_mmaps_max = mp_.n_mmaps_max;
-  ms->mmap_threshold = mp_.mmap_threshold;
-  ms->check_action = check_action;
-  ms->max_sbrked_mem = main_arena.max_system_mem;
-  ms->max_total_mem = 0;
-  ms->n_mmaps = mp_.n_mmaps;
-  ms->max_n_mmaps = mp_.max_n_mmaps;
-  ms->mmapped_mem = mp_.mmapped_mem;
-  ms->max_mmapped_mem = mp_.max_mmapped_mem;
-  ms->using_malloc_checking = using_malloc_checking;
-  ms->max_fast = get_max_fast ();
-  ms->arena_test = mp_.arena_test;
-  ms->arena_max = mp_.arena_max;
-  ms->narenas = narenas;
-  (void) mutex_unlock (&main_arena.mutex);
-  return (void *) ms;
+  return NULL;
 }
+compat_symbol (libc, malloc_get_state, malloc_get_state, GLIBC_2_0);
 
 int
-__malloc_set_state (void *msptr)
+attribute_compat_text_section
+malloc_set_state (void *msptr)
 {
   struct malloc_save_state *ms = (struct malloc_save_state *) msptr;
 
@@ -612,6 +573,9 @@ __malloc_set_state (void *msptr)
 
   return 0;
 }
+compat_symbol (libc, malloc_set_state, malloc_set_state, GLIBC_2_0);
+
+#endif	/* SHLIB_COMPAT */
 
 /*
  * Local variables:
diff --git a/malloc/malloc.c b/malloc/malloc.c
index ac0f751..b054fe6 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -5266,8 +5266,6 @@ strong_alias (__libc_mallopt, __mallopt) weak_alias (__libc_mallopt, mallopt)
 weak_alias (__malloc_stats, malloc_stats)
 weak_alias (__malloc_usable_size, malloc_usable_size)
 weak_alias (__malloc_trim, malloc_trim)
-weak_alias (__malloc_get_state, malloc_get_state)
-weak_alias (__malloc_set_state, malloc_set_state)
 
 
 /* ------------------------------------------------------------
diff --git a/malloc/malloc.h b/malloc/malloc.h
index 54b1862..e0c2788 100644
--- a/malloc/malloc.h
+++ b/malloc/malloc.h
@@ -134,13 +134,6 @@ extern void malloc_stats (void) __THROW;
 /* Output information about state of allocator to stream FP.  */
 extern int malloc_info (int __options, FILE *__fp) __THROW;
 
-/* Record the state of all malloc variables in an opaque data structure. */
-extern void *malloc_get_state (void) __THROW;
-
-/* Restore the state of all malloc variables from data obtained with
-   malloc_get_state(). */
-extern int malloc_set_state (void *__ptr) __THROW;
-
 /* Hooks for debugging and user-defined versions. */
 extern void (*__MALLOC_HOOK_VOLATILE __free_hook) (void *__ptr,
                                                    const void *)
diff --git a/malloc/tst-mallocstate.c b/malloc/tst-mallocstate.c
deleted file mode 100644
index a00d045..0000000
--- a/malloc/tst-mallocstate.c
+++ /dev/null
@@ -1,84 +0,0 @@
-/* Copyright (C) 2001-2016 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
-
-   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 "malloc.h"
-
-static int errors = 0;
-
-static void
-merror (const char *msg)
-{
-  ++errors;
-  printf ("Error: %s\n", msg);
-}
-
-static int
-do_test (void)
-{
-  void *p1, *p2;
-  void *save_state;
-  long i;
-
-  errno = 0;
-
-  p1 = malloc (10);
-  if (p1 == NULL)
-    merror ("malloc (10) failed.");
-
-  p2 = malloc (20);
-  if (p2 == NULL)
-    merror ("malloc (20) failed.");
-
-  free (malloc (10));
-
-  for (i = 0; i < 100; ++i)
-    {
-      save_state = malloc_get_state ();
-      if (save_state == NULL)
-        {
-          merror ("malloc_get_state () failed.");
-          break;
-        }
-      /*free (malloc (10)); This could change the top chunk! */
-      malloc_set_state (save_state);
-      p1 = realloc (p1, i * 4 + 4);
-      if (p1 == NULL)
-        merror ("realloc (i*4) failed.");
-      free (save_state);
-    }
-
-  p1 = realloc (p1, 40);
-  free (p2);
-  p2 = malloc (10);
-  if (p2 == NULL)
-    merror ("malloc (10) failed.");
-  free (p1);
-
-  return errors != 0;
-}
-
-/*
- * Local variables:
- * c-basic-offset: 2
- * End:
- */
-
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"