Add code from mcheck.c of glibc-1.09.1.

(freehook, reallochook): Handle null pointer arguments.
(__malloc_initialize) [GC_MCHECK]: Call mcheck.

src/ChangeLog

+2000-10-27  Gerd Moellmann  <gerd@gnu.org>
+
+	* gmalloc.c [GC_MCHECK]: Add code from mcheck.c of glibc-1.09.1.
+	(freehook, reallochook): Handle null pointer arguments.
+	(__malloc_initialize) [GC_MCHECK]: Call mcheck.
+
 2000-10-27  Stefan Monnier  <monnier@cs.yale.edu>
 
 	* regex.c (POP_FAILURE_REG_OR_COUNT, re_match_2_internal)

src/gmalloc.c

@@ -522,6 +522,10 @@ __malloc_initialize ()
   if (__malloc_initialized)
     return 0;
 
+#ifdef GC_MCHECK
+  mcheck (NULL);
+#endif
+
   if (__malloc_initialize_hook)
     (*__malloc_initialize_hook) ();
 
@@ -1718,3 +1722,242 @@ valloc (size)
 }
 
 #endif	/* Not ELIDE_VALLOC.  */
+
+#ifdef GC_MCHECK
+
+/* Standard debugging hooks for `malloc'.
+   Copyright 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
+   Written May 1989 by Mike Haertel.
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+This 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with this library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.
+
+   The author may be reached (Email) at the address mike@ai.mit.edu,
+   or (US mail) as Mike Haertel c/o Free Software Foundation.  */
+
+#ifdef emacs
+#include <stdio.h>
+#else
+#ifndef	_MALLOC_INTERNAL
+#define	_MALLOC_INTERNAL
+#include <malloc.h>
+#include <stdio.h>
+#endif
+#endif
+
+/* Old hook values.  */
+static void (*old_free_hook) __P ((__ptr_t ptr));
+static __ptr_t (*old_malloc_hook) __P ((__malloc_size_t size));
+static __ptr_t (*old_realloc_hook) __P ((__ptr_t ptr, __malloc_size_t size));
+
+/* Function to call when something awful happens.  */
+static void (*abortfunc) __P ((enum mcheck_status));
+
+/* Arbitrary magical numbers.  */
+#define MAGICWORD	0xfedabeeb
+#define MAGICFREE	0xd8675309
+#define MAGICBYTE	((char) 0xd7)
+#define MALLOCFLOOD	((char) 0x93)
+#define FREEFLOOD	((char) 0x95)
+
+struct hdr
+  {
+    __malloc_size_t size;		/* Exact size requested by user.  */
+    unsigned long int magic;	/* Magic number to check header integrity.  */
+  };
+
+#if	defined(_LIBC) || defined(STDC_HEADERS) || defined(USG)
+#define flood memset
+#else
+static void flood __P ((__ptr_t, int, __malloc_size_t));
+static void
+flood (ptr, val, size)
+     __ptr_t ptr;
+     int val;
+     __malloc_size_t size;
+{
+  char *cp = ptr;
+  while (size--)
+    *cp++ = val;
+}
+#endif
+
+static enum mcheck_status checkhdr __P ((const struct hdr *));
+static enum mcheck_status
+checkhdr (hdr)
+     const struct hdr *hdr;
+{
+  enum mcheck_status status;
+  switch (hdr->magic)
+    {
+    default:
+      status = MCHECK_HEAD;
+      break;
+    case MAGICFREE:
+      status = MCHECK_FREE;
+      break;
+    case MAGICWORD:
+      if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
+	status = MCHECK_TAIL;
+      else
+	status = MCHECK_OK;
+      break;
+    }
+  if (status != MCHECK_OK)
+    (*abortfunc) (status);
+  return status;
+}
+
+static void freehook __P ((__ptr_t));
+static void
+freehook (ptr)
+     __ptr_t ptr;
+{
+  struct hdr *hdr;
+    
+  if (ptr)
+    {
+      hdr = ((struct hdr *) ptr) - 1;
+      checkhdr (hdr);
+      hdr->magic = MAGICFREE;
+      flood (ptr, FREEFLOOD, hdr->size);
+    }
+  else
+    hdr = NULL;
+  
+  __free_hook = old_free_hook;
+  free (hdr);
+  __free_hook = freehook;
+}
+
+static __ptr_t mallochook __P ((__malloc_size_t));
+static __ptr_t
+mallochook (size)
+     __malloc_size_t size;
+{
+  struct hdr *hdr;
+
+  __malloc_hook = old_malloc_hook;
+  hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
+  __malloc_hook = mallochook;
+  if (hdr == NULL)
+    return NULL;
+
+  hdr->size = size;
+  hdr->magic = MAGICWORD;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
+  return (__ptr_t) (hdr + 1);
+}
+
+static __ptr_t reallochook __P ((__ptr_t, __malloc_size_t));
+static __ptr_t
+reallochook (ptr, size)
+     __ptr_t ptr;
+     __malloc_size_t size;
+{
+  struct hdr *hdr = NULL;
+  __malloc_size_t osize = 0;
+    
+  if (ptr)
+    {
+      hdr = ((struct hdr *) ptr) - 1;
+      osize = hdr->size;
+
+      checkhdr (hdr);
+      if (size < osize)
+	flood ((char *) ptr + size, FREEFLOOD, osize - size);
+    }
+  
+  __free_hook = old_free_hook;
+  __malloc_hook = old_malloc_hook;
+  __realloc_hook = old_realloc_hook;
+  hdr = (struct hdr *) realloc ((__ptr_t) hdr, sizeof (struct hdr) + size + 1);
+  __free_hook = freehook;
+  __malloc_hook = mallochook;
+  __realloc_hook = reallochook;
+  if (hdr == NULL)
+    return NULL;
+
+  hdr->size = size;
+  hdr->magic = MAGICWORD;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  if (size > osize)
+    flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
+  return (__ptr_t) (hdr + 1);
+}
+
+static void
+mabort (status)
+     enum mcheck_status status;
+{
+  const char *msg;
+  switch (status)
+    {
+    case MCHECK_OK:
+      msg = "memory is consistent, library is buggy";
+      break;
+    case MCHECK_HEAD:
+      msg = "memory clobbered before allocated block";
+      break;
+    case MCHECK_TAIL:
+      msg = "memory clobbered past end of allocated block";
+      break;
+    case MCHECK_FREE:
+      msg = "block freed twice";
+      break;
+    default:
+      msg = "bogus mcheck_status, library is buggy";
+      break;
+    }
+#ifdef __GNU_LIBRARY__
+  __libc_fatal (msg);
+#else
+  fprintf (stderr, "mcheck: %s\n", msg);
+  fflush (stderr);
+  abort ();
+#endif
+}
+
+static int mcheck_used = 0;
+
+int
+mcheck (func)
+     void (*func) __P ((enum mcheck_status));
+{
+  abortfunc = (func != NULL) ? func : &mabort;
+
+  /* These hooks may not be safely inserted if malloc is already in use.  */
+  if (!__malloc_initialized && !mcheck_used)
+    {
+      old_free_hook = __free_hook;
+      __free_hook = freehook;
+      old_malloc_hook = __malloc_hook;
+      __malloc_hook = mallochook;
+      old_realloc_hook = __realloc_hook;
+      __realloc_hook = reallochook;
+      mcheck_used = 1;
+    }
+
+  return mcheck_used ? 0 : -1;
+}
+
+enum mcheck_status
+mprobe (__ptr_t ptr)
+{
+  return mcheck_used ? checkhdr (ptr) : MCHECK_DISABLED;
+}
+
+#endif /* GC_MCHECK */