malloc/mcheck.c

   1 /* Standard debugging hooks for `malloc'.
   2    Copyright (C) 1990,91,92,93,94,95,96,97,99 Free Software Foundation, Inc.
   3    Written May 1989 by Mike Haertel.
   4
   5    This library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    This library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with this library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.
  19
  20    The author may be reached (Email) at the address mike@ai.mit.edu,
  21    or (US mail) as Mike Haertel c/o Free Software Foundation.  */
  22
  23 #ifndef _MALLOC_INTERNAL
  24 # define _MALLOC_INTERNAL
  25 # include <malloc.h>
  26 # include <mcheck.h>
  27 # include <stdio.h>
  28 # include <libintl.h>
  29 #endif
  30
  31 /* Old hook values.  */
  32 static void (*old_free_hook) __P ((__ptr_t ptr, __const __ptr_t));
  33 static __ptr_t (*old_malloc_hook) __P ((__malloc_size_t size, const __ptr_t));
  34 static __ptr_t (*old_realloc_hook) __P ((__ptr_t ptr, __malloc_size_t size,
  35                                          __const __ptr_t));
  36
  37 /* Function to call when something awful happens.  */
  38 static void (*abortfunc) __P ((enum mcheck_status));
  39
  40 /* Arbitrary magical numbers.  */
  41 #define MAGICWORD       0xfedabeeb
  42 #define MAGICFREE       0xd8675309
  43 #define MAGICBYTE       ((char) 0xd7)
  44 #define MALLOCFLOOD     ((char) 0x93)
  45 #define FREEFLOOD       ((char) 0x95)
  46
  47 struct hdr
  48   {
  49     __malloc_size_t size;               /* Exact size requested by user.  */
  50     unsigned long int magic;    /* Magic number to check header integrity.  */
  51   };
  52
  53 #if defined _LIBC || defined STDC_HEADERS || defined USG
  54 # include <string.h>
  55 # define flood memset
  56 #else
  57 static void flood __P ((__ptr_t, int, __malloc_size_t));
  58 static void
  59 flood (ptr, val, size)
  60      __ptr_t ptr;
  61      int val;
  62      __malloc_size_t size;
  63 {
  64   char *cp = ptr;
  65   while (size--)
  66     *cp++ = val;
  67 }
  68 #endif
  69
  70 static enum mcheck_status checkhdr __P ((const struct hdr *));
  71 static enum mcheck_status
  72 checkhdr (hdr)
  73      const struct hdr *hdr;
  74 {
  75   enum mcheck_status status;
  76   switch (hdr->magic)
  77     {
  78     default:
  79       status = MCHECK_HEAD;
  80       break;
  81     case MAGICFREE:
  82       status = MCHECK_FREE;
  83       break;
  84     case MAGICWORD:
  85       if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
  86         status = MCHECK_TAIL;
  87       else
  88         status = MCHECK_OK;
  89       break;
  90     }
  91   if (status != MCHECK_OK)
  92     (*abortfunc) (status);
  93   return status;
  94 }
  95
  96 static void freehook __P ((__ptr_t, const __ptr_t));
  97 static void
  98 freehook (ptr, caller)
  99      __ptr_t ptr;
 100      const __ptr_t caller;
 101 {
 102   if (ptr)
 103     {
 104       struct hdr *hdr = ((struct hdr *) ptr) - 1;
 105       checkhdr (hdr);
 106       hdr->magic = MAGICFREE;
 107       flood (ptr, FREEFLOOD, hdr->size);
 108       ptr = (__ptr_t) hdr;
 109     }
 110   __free_hook = old_free_hook;
 111   if (old_free_hook != NULL)
 112     (*old_free_hook) (ptr, caller);
 113   else
 114     free (ptr);
 115   __free_hook = freehook;
 116 }
 117
 118 static __ptr_t mallochook __P ((__malloc_size_t, const __ptr_t));
 119 static __ptr_t
 120 mallochook (size, caller)
 121      __malloc_size_t size;
 122      const __ptr_t caller;
 123 {
 124   struct hdr *hdr;
 125
 126   __malloc_hook = old_malloc_hook;
 127   if (old_malloc_hook != NULL)
 128     hdr = (struct hdr *) (*old_malloc_hook) (sizeof (struct hdr) + size + 1,
 129                                              caller);
 130   else
 131     hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
 132   __malloc_hook = mallochook;
 133   if (hdr == NULL)
 134     return NULL;
 135
 136   hdr->size = size;
 137   hdr->magic = MAGICWORD;
 138   ((char *) &hdr[1])[size] = MAGICBYTE;
 139   flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
 140   return (__ptr_t) (hdr + 1);
 141 }
 142
 143 static __ptr_t reallochook __P ((__ptr_t, __malloc_size_t, const __ptr_t));
 144 static __ptr_t
 145 reallochook (ptr, size, caller)
 146      __ptr_t ptr;
 147      __malloc_size_t size;
 148      const __ptr_t caller;
 149 {
 150   struct hdr *hdr;
 151   __malloc_size_t osize;
 152
 153   if (ptr)
 154     {
 155       hdr = ((struct hdr *) ptr) - 1;
 156       osize = hdr->size;
 157
 158       checkhdr (hdr);
 159       if (size < osize)
 160         flood ((char *) ptr + size, FREEFLOOD, osize - size);
 161     }
 162   else
 163     {
 164       osize = 0;
 165       hdr = NULL;
 166     }
 167   __free_hook = old_free_hook;
 168   __malloc_hook = old_malloc_hook;
 169   __realloc_hook = old_realloc_hook;
 170   if (old_realloc_hook != NULL)
 171     hdr = (struct hdr *) (*old_realloc_hook) ((__ptr_t) hdr,
 172                                               sizeof (struct hdr) + size + 1,
 173                                               caller);
 174   else
 175     hdr = (struct hdr *) realloc ((__ptr_t) hdr,
 176                                   sizeof (struct hdr) + size + 1);
 177   __free_hook = freehook;
 178   __malloc_hook = mallochook;
 179   __realloc_hook = reallochook;
 180   if (hdr == NULL)
 181     return NULL;
 182
 183   hdr->size = size;
 184   hdr->magic = MAGICWORD;
 185   ((char *) &hdr[1])[size] = MAGICBYTE;
 186   if (size > osize)
 187     flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
 188   return (__ptr_t) (hdr + 1);
 189 }
 190
 191 static void mabort __P ((enum mcheck_status status));
 192 static void
 193 mabort (status)
 194      enum mcheck_status status;
 195 {
 196   const char *msg;
 197   switch (status)
 198     {
 199     case MCHECK_OK:
 200       msg = _("memory is consistent, library is buggy\n");
 201       break;
 202     case MCHECK_HEAD:
 203       msg = _("memory clobbered before allocated block\n");
 204       break;
 205     case MCHECK_TAIL:
 206       msg = _("memory clobbered past end of allocated block\n");
 207       break;
 208     case MCHECK_FREE:
 209       msg = _("block freed twice\n");
 210       break;
 211     default:
 212       msg = _("bogus mcheck_status, library is buggy\n");
 213       break;
 214     }
 215 #ifdef _LIBC
 216   __libc_fatal (msg);
 217 #else
 218   fprintf (stderr, "mcheck: %s", msg);
 219   fflush (stderr);
 220   abort ();
 221 #endif
 222 }
 223
 224 static int mcheck_used;
 225
 226 int
 227 mcheck (func)
 228      void (*func) __P ((enum mcheck_status));
 229 {
 230   abortfunc = (func != NULL) ? func : &mabort;
 231
 232   /* These hooks may not be safely inserted if malloc is already in use.  */
 233   if (__malloc_initialized <= 0 && !mcheck_used)
 234     {
 235       old_free_hook = __free_hook;
 236       __free_hook = freehook;
 237       old_malloc_hook = __malloc_hook;
 238       __malloc_hook = mallochook;
 239       old_realloc_hook = __realloc_hook;
 240       __realloc_hook = reallochook;
 241       mcheck_used = 1;
 242     }
 243
 244   return mcheck_used ? 0 : -1;
 245 }
 246
 247 enum mcheck_status
 248 mprobe (__ptr_t ptr)
 249 {
 250   return mcheck_used ? checkhdr (((struct hdr *) ptr) - 1) : MCHECK_DISABLED;
 251 }