gdb/mcheck.c

   1 /* Standard debugging hooks for `malloc'.
   2    Copyright 1990 Free Software Foundation
   3                   Written May 1989 by Mike Haertel.
   4
   5    The author may be reached (Email) at the address mike@ai.mit.edu,
   6    or (US mail) as Mike Haertel c/o Free Software Foundation.
   7
   8 This program is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2 of the License, or
  11 (at your option) any later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  21
  22 #include "ansidecl.h"
  23 #define size_t unsigned int
  24 #define ptrdiff_t int
  25 #define NULL 0
  26 #define __ONEFILE
  27 #include "gmalloc.h"
  28
  29 /* Old hook values.  */
  30 static void EXFUN((*old_free_hook), (PTR ptr));
  31 static PTR EXFUN((*old_malloc_hook), (size_t size));
  32 static PTR EXFUN((*old_realloc_hook), (PTR ptr, size_t size));
  33
  34
  35 /* Function to call when something awful happens. */
  36 extern void abort();
  37 static void EXFUN((*abortfunc), (NOARGS)) = (void (*)()) abort;
  38
  39 /* Arbitrary magical numbers.  */
  40 #define MAGICWORD       0xfedabeeb
  41 #define MAGICBYTE       ((char) 0xd7)
  42
  43 struct hdr
  44   {
  45     size_t size;                /* Exact size requested by user.  */
  46     unsigned int magic;         /* Magic number to check header integrity.  */
  47   };
  48
  49 static void
  50 DEFUN(checkhdr, (hdr), CONST struct hdr *hdr)
  51 {
  52   if (hdr->magic != MAGICWORD || ((char *) &hdr[1])[hdr->size] != MAGICBYTE)
  53     (*abortfunc)();
  54 }
  55
  56 static void
  57 DEFUN(freehook, (ptr), PTR ptr)
  58 {
  59   struct hdr *hdr = ((struct hdr *) ptr) - 1;
  60   checkhdr(hdr);
  61   hdr->magic = 0;
  62   __free_hook = old_free_hook;
  63   free(hdr);
  64   __free_hook = freehook;
  65 }
  66
  67 static PTR
  68 DEFUN(mallochook, (size), size_t size)
  69 {
  70   struct hdr *hdr;
  71
  72   __malloc_hook = old_malloc_hook;
  73   hdr = (struct hdr *) malloc(sizeof(struct hdr) + size + 1);
  74   __malloc_hook = mallochook;
  75   if (hdr == NULL)
  76     return NULL;
  77
  78   hdr->size = size;
  79   hdr->magic = MAGICWORD;
  80   ((char *) &hdr[1])[size] = MAGICBYTE;
  81   return (PTR) (hdr + 1);
  82 }
  83
  84 static PTR
  85 DEFUN(reallochook, (ptr, size), PTR ptr AND size_t size)
  86 {
  87   struct hdr *hdr = ((struct hdr *) ptr) - 1;
  88
  89   checkhdr(hdr);
  90   __free_hook = old_free_hook;
  91   __malloc_hook = old_malloc_hook;
  92   __realloc_hook = old_realloc_hook;
  93   hdr = (struct hdr *) realloc((PTR) hdr, sizeof(struct hdr) + size + 1);
  94   __free_hook = freehook;
  95   __malloc_hook = mallochook;
  96   __realloc_hook = reallochook;
  97   if (hdr == NULL)
  98     return NULL;
  99
 100   hdr->size = size;
 101   ((char *) &hdr[1])[size] = MAGICBYTE;
 102   return (PTR) (hdr + 1);
 103 }
 104
 105 void
 106 DEFUN(mcheck, (func), void EXFUN((*func), (NOARGS)))
 107 {
 108   static int mcheck_used = 0;
 109
 110   if (func)
 111     abortfunc = func;
 112
 113   /* These hooks may not be safely inserted if malloc is already in use.  */
 114   if (!__malloc_initialized && !mcheck_used)
 115     {
 116       old_free_hook = __free_hook;
 117       __free_hook = freehook;
 118       old_malloc_hook = __malloc_hook;
 119       __malloc_hook = mallochook;
 120       old_realloc_hook = __realloc_hook;
 121       __realloc_hook = reallochook;
 122       mcheck_used = 1;
 123     }
 124 }