[PATCH] malloc: Deprecate hook variables, __default_morecore, <mcheck.h>

[fweimer at redhat dot com (Florian Weimer)]

The original round of hook variable deprecations missed
__after_morecore_hook and __morecore.  __default_morecore is just
an implementation detail.

The functionality in <mcheck.h> will eventually be replaced with
no-op functions (and a separate, preloadable DSO).

2016-10-26  Florian Weimer  <fweimer@redhat.com>

	* malloc/mcheck.h (__MCHECK_DEPRECATED): Define.
	(mcheck, mcheck_pedantic, mcheck_check_all, mprobe, mtrace)
	(muntrace): Deprecate.
	* malloc/malloc.h (__morecore, __default_morecore)
	(__after_morecore_hook): Likewise.

diff --git a/NEWS b/NEWS
index ea1a0e0..7cbaa28 100644
--- a/NEWS
+++ b/NEWS
@@ -67,6 +67,11 @@ Version 2.25
   for the Linux quota interface which predates kernel version 2.4.22 has
   been removed.
 
+* <mcheck.h> and all malloc hook functions are now deprecated.  Future
+  implementations of the mcheck- and mtrace-related functions will not have
+  any effect, and glibc will stop calling the hook functions from its malloc
+  implementation.
+
 * The malloc_get_state and malloc_set_state functions have been removed.
   Already-existing binaries that dynamically link to these functions will
   get a hidden implementation in which malloc_get_state is a stub.  As far
diff --git a/malloc/malloc.h b/malloc/malloc.h
index e0c2788..a18401e 100644
--- a/malloc/malloc.h
+++ b/malloc/malloc.h
@@ -68,11 +68,11 @@ extern void *pvalloc (size_t __size) __THROW __attribute_malloc__ __wur;
 
 /* Underlying allocation function; successive calls should return
    contiguous pieces of memory.  */
-extern void *(*__morecore) (ptrdiff_t __size);
+extern void *(*__morecore) (ptrdiff_t __size) __MALLOC_DEPRECATED;
 
 /* Default value of `__morecore'.  */
 extern void *__default_morecore (ptrdiff_t __size)
-__THROW __attribute_malloc__;
+__THROW __attribute_malloc__ __MALLOC_DEPRECATED;
 
 /* SVID2/XPG mallinfo structure */
 
@@ -149,7 +149,8 @@ extern void *(*__MALLOC_HOOK_VOLATILE __memalign_hook)(size_t __alignment,
                                                        size_t __size,
                                                        const void *)
 __MALLOC_DEPRECATED;
-extern void (*__MALLOC_HOOK_VOLATILE __after_morecore_hook) (void);
+extern void (*__MALLOC_HOOK_VOLATILE __after_morecore_hook) (void)
+__MALLOC_DEPRECATED;
 
 /* Activate a standard set of debugging hooks. */
 extern void __malloc_check_init (void) __THROW __MALLOC_DEPRECATED;
diff --git a/malloc/mcheck.h b/malloc/mcheck.h
index 416fcd6..aa74b1b 100644
--- a/malloc/mcheck.h
+++ b/malloc/mcheck.h
@@ -15,11 +15,20 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+/* Note: This header file is deprecated and will be removed in a
+   future glibc version.  */
+
 #ifndef _MCHECK_H
 #define _MCHECK_H       1
 
 #include <features.h>
 
+#ifdef _LIBC
+# define __MCHECK_DEPRECATED
+#else
+# define __MCHECK_DEPRECATED __attribute_deprecated__
+#endif
+
 __BEGIN_DECLS
 
 /* Return values for `mprobe': these are the kinds of inconsistencies that
@@ -38,23 +47,25 @@ enum mcheck_status
    before `malloc' is ever called.  ABORTFUNC is called with an error code
    (see enum above) when an inconsistency is detected.  If ABORTFUNC is
    null, the standard function prints on stderr and then calls `abort'.  */
-extern int mcheck (void (*__abortfunc)(enum mcheck_status)) __THROW;
+extern int mcheck (void (*__abortfunc)(enum mcheck_status))
+  __THROW __MCHECK_DEPRECATED;
 
 /* Similar to `mcheck' but performs checks for all block whenever one of
    the memory handling functions is called.  This can be very slow.  */
-extern int mcheck_pedantic (void (*__abortfunc)(enum mcheck_status)) __THROW;
+extern int mcheck_pedantic (void (*__abortfunc)(enum mcheck_status))
+  __THROW __MCHECK_DEPRECATED;
 
 /* Force check of all blocks now.  */
-extern void mcheck_check_all (void);
+extern void mcheck_check_all (void) __MCHECK_DEPRECATED;
 
 /* Check for aberrations in a particular malloc'd block.  You must have
    called `mcheck' already.  These are the same checks that `mcheck' does
    when you free or reallocate a block.  */
-extern enum mcheck_status mprobe (void *__ptr) __THROW;
+extern enum mcheck_status mprobe (void *__ptr) __THROW __MCHECK_DEPRECATED;
 
 /* Activate a standard collection of tracing hooks.  */
-extern void mtrace (void) __THROW;
-extern void muntrace (void) __THROW;
+extern void mtrace (void) __THROW __MCHECK_DEPRECATED;
+extern void muntrace (void) __THROW __MCHECK_DEPRECATED;
 
 __END_DECLS
 #endif /* mcheck.h */