This is gnu lib malloc from NetBSD verbatium, here is the version info

that Chris created:
this version of GNU malloc was obtained from prep.ai.mit.edu on
9/22/1993.  There was no version noted.

1 files changed, 133 insertions, 0 deletions

diff --git a/gnu/lib/libmalloc/mcheck.c b/gnu/lib/libmalloc/mcheck.c
new file mode 100644
index 0000000..f7d9d4f
--- /dev/null
+++ b/gnu/lib/libmalloc/mcheck.c
@@ -0,0 +1,133 @@
+/* Standard debugging hooks for `malloc'.
+   Copyright 1990, 1991, 1992, 1993 Free Software Foundation
+   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.  */
+
+#ifndef	_MALLOC_INTERNAL
+#define	_MALLOC_INTERNAL
+#include <malloc.h>
+#endif
+
+/* Old hook values.  */
+static void (*old_free_hook) __P ((__ptr_t ptr));
+static __ptr_t (*old_malloc_hook) __P ((size_t size));
+static __ptr_t (*old_realloc_hook) __P ((__ptr_t ptr, size_t size));
+
+/* Function to call when something awful happens.  */
+static void (*abortfunc) __P ((void));
+
+/* Arbitrary magical numbers.  */
+#define MAGICWORD	0xfedabeeb
+#define MAGICBYTE	((char) 0xd7)
+
+struct hdr
+  {
+    size_t size;		/* Exact size requested by user.  */
+    unsigned long int magic;	/* Magic number to check header integrity.  */
+  };
+
+static void checkhdr __P ((const struct hdr *));
+static void
+checkhdr (hdr)
+     const struct hdr *hdr;
+{
+  if (hdr->magic != MAGICWORD || ((char *) &hdr[1])[hdr->size] != MAGICBYTE)
+    (*abortfunc) ();
+}
+
+static void freehook __P ((__ptr_t));
+static void
+freehook (ptr)
+     __ptr_t ptr;
+{
+  struct hdr *hdr = ((struct hdr *) ptr) - 1;
+  checkhdr (hdr);
+  hdr->magic = 0;
+  __free_hook = old_free_hook;
+  free (hdr);
+  __free_hook = freehook;
+}
+
+static __ptr_t mallochook __P ((size_t));
+static __ptr_t
+mallochook (size)
+     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;
+  return (__ptr_t) (hdr + 1);
+}
+
+static __ptr_t reallochook __P ((__ptr_t, size_t));
+static __ptr_t
+reallochook (ptr, size)
+     __ptr_t ptr;
+     size_t size;
+{
+  struct hdr *hdr = ((struct hdr *) ptr) - 1;
+
+  checkhdr (hdr);
+  __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;
+  ((char *) &hdr[1])[size] = MAGICBYTE;
+  return (__ptr_t) (hdr + 1);
+}
+
+int
+mcheck (func)
+     void (*func) __P ((void));
+{
+  extern void abort __P ((void));
+  static int mcheck_used = 0;
+
+  abortfunc = (func != NULL) ? func : abort;
+
+  /* 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;
+}