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heap_debug.c

/* Distributed Checksum Clearinghouse heap debugging
 *
 * Copyright (c) 2005 by Rhyolite Software
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND RHYOLITE SOFTWARE DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL RHYOLITE SOFTWARE
 * BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
 * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 *
 * Rhyolite Software DCC 1.2.74-1.13 $Revision$
 */

#include "dcc_defs.h"
#include "dcc_heap_debug.h"
#include <stdio.h>

void dcc_malloc_lock(void);
void dcc_malloc_unlock(void);

#ifdef UNIX
#include <unistd.h>
#if defined(FreeBSD) || defined(linux)
#define NO_MALLOC_OPTIONS
#endif
char dcc_malloc_options[] = "A";
#else /* !UNIX */
#include "malloc.h"
#endif /* !UNIX */


typedef u_long SENTINEL;
#define HEAD_SENTINEL_VALUE 0xdeadbeaf
#define TAIL_SENTINEL_VALUE 0xbeafdead

typedef struct mdbg{
    SENTINEL      head;
    struct mdbg *fwd, *bak;
    SENTINEL      *tail;
} MDBG;

u_int dcc_num_mdbg;                 /* global to suppress warnings */
MDBG *dcc_mdbg_chain;               /*    when not used */
MDBG *bad_mp;
int bad_i;

/* leave a few names outside to make some `ar`s happy */
#ifdef DEBUG_HEAP


/* this needs to do as little as possible to avoid calling malloc()
 *    global and no NRATTRIB to avoid confusion in dumps */
void
dcc_heap_abort(const char *m)
{
#ifdef UNIX
      write(STDERR_FILENO, m, strlen(m));
      abort();
#else
      bad_message_box("heap_debug", 1, m);
#endif
}



char *
dcc_strdup(const char *s)
{
      char *p;

      p = dcc_malloc(strlen(s)+1);
      strcpy(p, s);
      return p;
}



void
dcc_malloc_check(void)
{
      MDBG *mp;
      u_int i;

      i = dcc_num_mdbg;
      if (!i)
            return;

      mp = dcc_mdbg_chain;
      for (;;) {
            if (mp->head != HEAD_SENTINEL_VALUE
                || *mp->tail != TAIL_SENTINEL_VALUE)
                  dcc_heap_abort("trashed heap sentinel");
            if (mp->bak->fwd != mp
                || mp->fwd->bak != mp) {
                  bad_mp = mp;
                  bad_i = i;
                  dcc_heap_abort("malloc chain trashed");
            }
            if (--i == 0) {
                  if (mp->fwd != dcc_mdbg_chain) {
                        bad_mp = mp;
                        bad_i = i;
                        dcc_heap_abort("wrong malloc chain too long");
                  }
#ifndef UNIX
                  i = _heapchk();
                  if (i != _HEAPOK && i != _HEAPEMPTY)
                        dcc_heap_abort("heapchk() failed");
#endif
                  return;
            } else if (mp->fwd == dcc_mdbg_chain) {
                  bad_mp = mp;
                  bad_i = i;
                  dcc_heap_abort("wrong malloc chain too short");
            }
            mp = mp->fwd;
      }
}



void *
dcc_malloc(size_t len)
{
      MDBG *mp;

#if defined(UNIX) && !defined(NO_MALLOC_OPTIONS)
      if (!malloc_options) {
            malloc_options = dcc_malloc_options;
      } else if (malloc_options != dcc_malloc_options) {
            dcc_heap_abort("malloc_options already set");
      }
#endif

      dcc_malloc_lock();
      dcc_malloc_check();

      if (!len)
            dcc_heap_abort("malloc(0)");

      len += sizeof(MDBG) + sizeof(mp->tail);
      len += (sizeof(mp->tail) - len) & (sizeof(mp->tail)-1); /* align tail */

      mp = malloc(len);
      if (!mp)
            return mp;

      if (!dcc_num_mdbg) {
            mp->fwd = mp->bak = mp;
      } else {
            mp->bak = dcc_mdbg_chain;
            mp->fwd = dcc_mdbg_chain->fwd;
            mp->bak->fwd = mp;
            mp->fwd->bak = mp;
      }
      dcc_mdbg_chain = mp;
      mp->head = HEAD_SENTINEL_VALUE;
      mp->tail = (SENTINEL *)((u_char *)mp+len-sizeof(mp->tail));
      *mp->tail = TAIL_SENTINEL_VALUE;
      dcc_num_mdbg++;
      dcc_malloc_unlock();

      return (mp+1);
}



void *
dcc_calloc(size_t n, size_t s)
{
      void *p;

      s *= n;
      if (s == 0)
            dcc_heap_abort("zero calloc() size");
      p = dcc_malloc(s);
      if (!p)
            return p;
      memset(p, 0, s);
      return p;
}



void
dcc_free(void *p)
{
      int i;
      MDBG *mp;

      dcc_malloc_lock();
      dcc_malloc_check();
      i = dcc_num_mdbg;
      mp = dcc_mdbg_chain;
      for (;;) {
            if (!i)
                  dcc_heap_abort("freeing non-free");
            if (mp+1 == p)
                  break;
            mp = mp->fwd;
            i--;
      }

      if (dcc_mdbg_chain == mp)
            dcc_mdbg_chain = mp->fwd;
      mp->bak->fwd = mp->fwd;
      mp->fwd->bak = mp->bak;
      dcc_num_mdbg--;
      memset(mp, 0xf1, (u_char *)mp->tail+sizeof(mp->tail)-(u_char *)mp);
      dcc_malloc_check();
      dcc_malloc_unlock();

      free(mp);
}
#endif /* DEBUG_HEAP */

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