diff mbox

Revert __malloc_initialize_hook symbol poisoning

Message ID 20160613122031.80ABE4091079D@oldenburg.str.redhat.com
State New
Headers show

Commit Message

Florian Weimer June 13, 2016, 12:20 p.m. UTC 
It turns out the Emacs-internal malloc implementation uses
__malloc_* symbols.  If glibc poisons them in <stdc-pre.h>,
Emacs will no longer compile.

2016-06-13  Florian Weimer  <fweimer@redhat.com>

	Revert symbol poisoning of  __malloc_initialize_hook.
	* include/stdc-predef.h (__malloc_initialize_hook): Remove
	poisoning.
	* malloc/Makefile: Remove un-poisoning.
	* malloc/arena.c (ptmalloc_init): Use __malloc_initialize_hook
	instead of old__malloc_initialize_hook.
	* malloc/malloc-hooks.h: Likewise.
	* malloc/malloc.c: Likewise.
	* malloc/mcheck-init.c: Likewise.

Comments

Andreas Schwab June 20, 2016, 9 a.m. UTC | #1 
fweimer@redhat.com (Florian Weimer) writes:

> It turns out the Emacs-internal malloc implementation uses
> __malloc_* symbols.  If glibc poisons them in <stdc-pre.h>,
> Emacs will no longer compile.

Please install.  I don't think we should be in the business of poisoning
identifiers, even if they are in the implementation name space.

Andreas.
Florian Weimer June 23, 2016, 3:07 p.m. UTC | #2 
On 06/20/2016 11:00 AM, Andreas Schwab wrote:
> fweimer@redhat.com (Florian Weimer) writes:
>
>> It turns out the Emacs-internal malloc implementation uses
>> __malloc_* symbols.  If glibc poisons them in <stdc-pre.h>,
>> Emacs will no longer compile.
>
> Please install.  I don't think we should be in the business of poisoning
> identifiers, even if they are in the implementation name space.

It is the only way to remove a symbol from the API which is used via 
interposition, which is why I went down this route in this case.

I would have done this for the other malloc hooks, but it would still 
break Emacs compatibility, so I'm just going to remove them from the header.

Florian
diff mbox

Patch

diff --git a/include/stdc-predef.h b/include/stdc-predef.h
index 52cf8d1..f9f7f73 100644
--- a/include/stdc-predef.h
+++ b/include/stdc-predef.h
@@ -57,11 +57,4 @@ 
 /* We do not support C11 <threads.h>.  */
 #define __STDC_NO_THREADS__		1
 
-/* Remove symbols from the API which can be interposed.  */
-#if defined (__GNUC__)
-# if __GNUC__ >= 4
-#  pragma GCC poison __malloc_initialize_hook
-# endif	 /* __GNUC__ >= 4 */
-#endif	/* __GNUC__ */
-
 #endif
diff --git a/malloc/Makefile b/malloc/Makefile
index 91eb17d..fa1730e 100644
--- a/malloc/Makefile
+++ b/malloc/Makefile
@@ -115,20 +115,6 @@  endif
 
 include ../Rules
 
-# Support references to removed APIs.  We use #pragma GCC poison in
-# <stdc-predef.h> to make it difficult to reference them.  For select
-# source files, we work around this poisoning by defining a macro on
-# the command line (which is processed before <stdc-predef.h> and can
-# therefore use tokens poisoned later).
-poisoned_apis = \
-  __malloc_initialize_hook \
-
-unpoisoned_api_defines := \
-  $(foreach sym,$(poisoned_apis), \
-    $(patsubst %,-Dold%, $(sym))=$(sym))
-CPPFLAGS-malloc.c = $(unpoisoned_api_defines)
-CPPFLAGS-mcheck-init.c = $(unpoisoned_api_defines)
-
 CFLAGS-mcheck-init.c = $(PIC-ccflag)
 CFLAGS-obstack.c = $(uses-callbacks)
 
diff --git a/malloc/arena.c b/malloc/arena.c
index 64a118c..ed5a4d5 100644
--- a/malloc/arena.c
+++ b/malloc/arena.c
@@ -341,7 +341,7 @@  ptmalloc_init (void)
         __malloc_check_init ();
     }
 #if HAVE_MALLOC_INIT_HOOK
-  void (*hook) (void) = atomic_forced_read (old__malloc_initialize_hook);
+  void (*hook) (void) = atomic_forced_read (__malloc_initialize_hook);
   if (hook != NULL)
     (*hook)();
 #endif
diff --git a/malloc/malloc-hooks.h b/malloc/malloc-hooks.h
index 3be391b..c7aa8b2 100644
--- a/malloc/malloc-hooks.h
+++ b/malloc/malloc-hooks.h
@@ -19,9 +19,6 @@ 
 #ifndef _MALLOC_HOOKS_H
 #define _MALLOC_HOOKS_H
 
-/* These hooks are no longer part of the public API and are poisoned
-   in <stdc-predef.h>.  Their names here reflect the command-line
-   mapping which is used inside glibc to get past the poisoning.  */
-void (*old__malloc_initialize_hook) (void);
+void (*__malloc_initialize_hook) (void);
 
 #endif  /* _MALLOC_HOOKS_H */
diff --git a/malloc/malloc.c b/malloc/malloc.c
index 21a912a..1f5f166 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -1851,9 +1851,9 @@  static void *memalign_hook_ini (size_t alignment, size_t sz,
                                 const void *caller) __THROW;
 
 #if HAVE_MALLOC_INIT_HOOK
-void weak_variable (*old__malloc_initialize_hook) (void) = NULL;
-compat_symbol (libc, old__malloc_initialize_hook,
-	       old__malloc_initialize_hook, GLIBC_2_0);
+void weak_variable (*__malloc_initialize_hook) (void) = NULL;
+compat_symbol (libc, __malloc_initialize_hook,
+	       __malloc_initialize_hook, GLIBC_2_0);
 #endif
 
 void weak_variable (*__free_hook) (void *__ptr,
diff --git a/malloc/mcheck-init.c b/malloc/mcheck-init.c
index 3218bb0..8d63dd3 100644
--- a/malloc/mcheck-init.c
+++ b/malloc/mcheck-init.c
@@ -27,4 +27,4 @@  turn_on_mcheck (void)
   mcheck (NULL);
 }
 
-void (*old__malloc_initialize_hook) (void) = turn_on_mcheck;
+void (*__malloc_initialize_hook) (void) = turn_on_mcheck;