gnu/lib/libmalloc/mcheck.c

   1 /* Standard debugging hooks for `malloc'.
   2    Copyright 1990, 1991, 1992, 1993 Free Software Foundation
   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
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, 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 #endif
  27
  28 /* Old hook values.  */
  29 static void (*old_free_hook) __P ((__ptr_t ptr));
  30 static __ptr_t (*old_malloc_hook) __P ((size_t size));
  31 static __ptr_t (*old_realloc_hook) __P ((__ptr_t ptr, size_t size));
  32
  33 /* Function to call when something awful happens.  */
  34 static void (*abortfunc) __P ((void));
  35
  36 /* Arbitrary magical numbers.  */
  37 #define MAGICWORD       0xfedabeeb
  38 #define MAGICBYTE       ((char) 0xd7)
  39
  40 struct hdr
  41   {
  42     size_t size;                /* Exact size requested by user.  */
  43     unsigned long int magic;    /* Magic number to check header integrity.  */
  44   };
  45
  46 static void checkhdr __P ((const struct hdr *));
  47 static void
  48 checkhdr (hdr)
  49      const struct hdr *hdr;
  50 {
  51   if (hdr->magic != MAGICWORD || ((char *) &hdr[1])[hdr->size] != MAGICBYTE)
  52     (*abortfunc) ();
  53 }
  54
  55 static void freehook __P ((__ptr_t));
  56 static void
  57 freehook (ptr)
  58      __ptr_t ptr;
  59 {
  60   struct hdr *hdr = ((struct hdr *) ptr) - 1;
  61   checkhdr (hdr);
  62   hdr->magic = 0;
  63   __free_hook = old_free_hook;
  64   free (hdr);
  65   __free_hook = freehook;
  66 }
  67
  68 static __ptr_t mallochook __P ((size_t));
  69 static __ptr_t
  70 mallochook (size)
  71      size_t size;
  72 {
  73   struct hdr *hdr;
  74
  75   __malloc_hook = old_malloc_hook;
  76   hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
  77   __malloc_hook = mallochook;
  78   if (hdr == NULL)
  79     return NULL;
  80
  81   hdr->size = size;
  82   hdr->magic = MAGICWORD;
  83   ((char *) &hdr[1])[size] = MAGICBYTE;
  84   return (__ptr_t) (hdr + 1);
  85 }
  86
  87 static __ptr_t reallochook __P ((__ptr_t, size_t));
  88 static __ptr_t
  89 reallochook (ptr, size)
  90      __ptr_t ptr;
  91      size_t size;
  92 {
  93   struct hdr *hdr = ((struct hdr *) ptr) - 1;
  94
  95   checkhdr (hdr);
  96   __free_hook = old_free_hook;
  97   __malloc_hook = old_malloc_hook;
  98   __realloc_hook = old_realloc_hook;
  99   hdr = (struct hdr *) realloc ((__ptr_t) hdr, sizeof (struct hdr) + size + 1);
 100   __free_hook = freehook;
 101   __malloc_hook = mallochook;
 102   __realloc_hook = reallochook;
 103   if (hdr == NULL)
 104     return NULL;
 105
 106   hdr->size = size;
 107   ((char *) &hdr[1])[size] = MAGICBYTE;
 108   return (__ptr_t) (hdr + 1);
 109 }
 110
 111 int
 112 mcheck (func)
 113      void (*func) __P ((void));
 114 {
 115   extern void abort __P ((void));
 116   static int mcheck_used = 0;
 117
 118   abortfunc = (func != NULL) ? func : abort;
 119
 120   /* These hooks may not be safely inserted if malloc is already in use.  */
 121   if (!__malloc_initialized && !mcheck_used)
 122     {
 123       old_free_hook = __free_hook;
 124       __free_hook = freehook;
 125       old_malloc_hook = __malloc_hook;
 126       __malloc_hook = mallochook;
 127       old_realloc_hook = __realloc_hook;
 128       __realloc_hook = reallochook;
 129       mcheck_used = 1;
 130     }
 131
 132   return mcheck_used ? 0 : -1;
 133 }