xref: /src/external/gpl2/libmalloc/dist/mcheck.c

/*	$NetBSD: mcheck.c,v 1.2 2016/01/13 21:56:38 christos Exp $	*/

/* 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 (at) ai.mit.edu,
   or (US mail) as Mike Haertel c/o Free Software Foundation.  */

#ifndef	_MALLOC_INTERNAL
#define	_MALLOC_INTERNAL
#include <malloc.h>
#include <stdlib.h>
#include <stdio.h>
#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 = ((struct hdr *) ptr) - 1;
  checkhdr (hdr);
  hdr->magic = MAGICFREE;
  flood (ptr, FREEFLOOD, hdr->size);
  __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 = ((struct hdr *) ptr) - 1;
  __malloc_size_t 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;
}