malloc: Remove __malloc_initialize_hook from the API [BZ #19564]

__malloc_initialize_hook is interposed by application code, so
the usual approach to define a compatibility symbol does not work.
This commit adds a new mechanism based on #pragma GCC poison in
<stdc-predef.h>.

1 files changed, 2 insertions, 22 deletions

diff --git a/manual/memory.texi b/manual/memory.texi
index a3ecc0d..92f041a 100644
--- a/manual/memory.texi
+++ b/manual/memory.texi
@@ -1370,19 +1370,6 @@ should make sure to restore all the hooks to their previous value.  When
 coming back from the recursive call, all the hooks should be resaved
 since a hook might modify itself.
 
-@comment malloc.h
-@comment GNU
-@defvar __malloc_initialize_hook
-The value of this variable is a pointer to a function that is called
-once when the malloc implementation is initialized.  This is a weak
-variable, so it can be overridden in the application with a definition
-like the following:
-
-@smallexample
-void (*@var{__malloc_initialize_hook}) (void) = my_init_hook;
-@end smallexample
-@end defvar
-
 An issue to look out for is the time at which the malloc hook functions
 can be safely installed.  If the hook functions call the malloc-related
 functions recursively, it is necessary that malloc has already properly
@@ -1393,11 +1380,6 @@ are assigned to @emph{before} the very first @code{malloc} call has
 completed, because otherwise a chunk obtained from the ordinary,
 un-hooked malloc may later be handed to @code{__free_hook}, for example.
 
-In both cases, the problem can be solved by setting up the hooks from
-within a user-defined function pointed to by
-@code{__malloc_initialize_hook}---then the hooks will be set up safely
-at the right time.
-
 Here is an example showing how to use @code{__malloc_hook} and
 @code{__free_hook} properly.  It installs a function that prints out
 information every time @code{malloc} or @code{free} is called.  We just
@@ -1413,11 +1395,8 @@ static void my_init_hook (void);
 static void *my_malloc_hook (size_t, const void *);
 static void my_free_hook (void*, const void *);
 
-/* Override initializing hook from the C library. */
-void (*__malloc_initialize_hook) (void) = my_init_hook;
-
 static void
-my_init_hook (void)
+my_init (void)
 @{
   old_malloc_hook = __malloc_hook;
   old_free_hook = __free_hook;
@@ -1465,6 +1444,7 @@ my_free_hook (void *ptr, const void *caller)
 
 main ()
 @{
+  my_init ();
   @dots{}
 @}
 @end smallexample