1 /* Standard debugging hooks for `malloc'.
2 Copyright (C) 1990-1997,1999,2000-2002,2007,2010
3 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Written May 1989 by Mike Haertel.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, write to the Free
19 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 #ifndef _MALLOC_INTERNAL
23 # define _MALLOC_INTERNAL
32 /* Old hook values. */
33 static void (*old_free_hook) (__ptr_t ptr, __const __ptr_t);
34 static __ptr_t (*old_malloc_hook) (__malloc_size_t size, const __ptr_t);
35 static __ptr_t (*old_memalign_hook) (__malloc_size_t alignment,
38 static __ptr_t (*old_realloc_hook) (__ptr_t ptr, __malloc_size_t size,
41 /* Function to call when something awful happens. */
42 static void (*abortfunc) (enum mcheck_status);
44 /* Arbitrary magical numbers. */
45 #define MAGICWORD 0xfedabeeb
46 #define MAGICFREE 0xd8675309
47 #define MAGICBYTE ((char) 0xd7)
48 #define MALLOCFLOOD ((char) 0x93)
49 #define FREEFLOOD ((char) 0x95)
53 __malloc_size_t size; /* Exact size requested by user. */
54 unsigned long int magic; /* Magic number to check header integrity. */
57 __ptr_t block; /* Real block allocated, for memalign. */
58 unsigned long int magic2; /* Extra, keeps us doubleword aligned. */
61 /* This is the beginning of the list of all memory blocks allocated.
62 It is only constructed if the pedantic testing is requested. */
63 static struct hdr *root;
65 static int mcheck_used;
67 /* Nonzero if pedentic checking of all blocks is requested. */
70 #if defined _LIBC || defined STDC_HEADERS || defined USG
74 static void flood (__ptr_t, int, __malloc_size_t);
76 flood (ptr, val, size)
87 static enum mcheck_status
88 checkhdr (const struct hdr *hdr)
90 enum mcheck_status status;
93 /* Maybe the mcheck used is disabled? This happens when we find
94 an error and report it. */
97 switch (hdr->magic ^ ((uintptr_t) hdr->prev + (uintptr_t) hdr->next))
100 status = MCHECK_HEAD;
103 status = MCHECK_FREE;
106 if (((char *) &hdr[1])[hdr->size] != MAGICBYTE)
107 status = MCHECK_TAIL;
108 else if ((hdr->magic2 ^ (uintptr_t) hdr->block) != MAGICWORD)
109 status = MCHECK_HEAD;
114 if (status != MCHECK_OK)
117 (*abortfunc) (status);
124 mcheck_check_all (void)
126 /* Walk through all the active blocks and test whether they were tempered
128 struct hdr *runp = root;
130 /* Temporarily turn off the checks. */
135 (void) checkhdr (runp);
140 /* Turn checks on again. */
144 libc_hidden_def (mcheck_check_all)
148 unlink_blk (struct hdr *ptr)
150 if (ptr->next != NULL)
152 ptr->next->prev = ptr->prev;
153 ptr->next->magic = MAGICWORD ^ ((uintptr_t) ptr->next->prev
154 + (uintptr_t) ptr->next->next);
156 if (ptr->prev != NULL)
158 ptr->prev->next = ptr->next;
159 ptr->prev->magic = MAGICWORD ^ ((uintptr_t) ptr->prev->prev
160 + (uintptr_t) ptr->prev->next);
167 link_blk (struct hdr *hdr)
172 hdr->magic = MAGICWORD ^ (uintptr_t) hdr->next;
174 /* And the next block. */
175 if (hdr->next != NULL)
177 hdr->next->prev = hdr;
178 hdr->next->magic = MAGICWORD ^ ((uintptr_t) hdr
179 + (uintptr_t) hdr->next->next);
183 freehook (__ptr_t ptr, const __ptr_t caller)
189 struct hdr *hdr = ((struct hdr *) ptr) - 1;
191 hdr->magic = MAGICFREE;
192 hdr->magic2 = MAGICFREE;
194 hdr->prev = hdr->next = NULL;
195 flood (ptr, FREEFLOOD, hdr->size);
198 __free_hook = old_free_hook;
199 if (old_free_hook != NULL)
200 (*old_free_hook) (ptr, caller);
203 __free_hook = freehook;
207 mallochook (__malloc_size_t size, const __ptr_t caller)
214 if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
216 __set_errno (ENOMEM);
220 __malloc_hook = old_malloc_hook;
221 if (old_malloc_hook != NULL)
222 hdr = (struct hdr *) (*old_malloc_hook) (sizeof (struct hdr) + size + 1,
225 hdr = (struct hdr *) malloc (sizeof (struct hdr) + size + 1);
226 __malloc_hook = mallochook;
233 hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
234 ((char *) &hdr[1])[size] = MAGICBYTE;
235 flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
236 return (__ptr_t) (hdr + 1);
240 memalignhook (__malloc_size_t alignment, __malloc_size_t size,
241 const __ptr_t caller)
244 __malloc_size_t slop;
250 slop = (sizeof *hdr + alignment - 1) & -alignment;
252 if (size > ~((size_t) 0) - (slop + 1))
254 __set_errno (ENOMEM);
258 __memalign_hook = old_memalign_hook;
259 if (old_memalign_hook != NULL)
260 block = (*old_memalign_hook) (alignment, slop + size + 1, caller);
262 block = memalign (alignment, slop + size + 1);
263 __memalign_hook = memalignhook;
267 hdr = ((struct hdr *) (block + slop)) - 1;
271 hdr->block = (__ptr_t) block;
272 hdr->magic2 = (uintptr_t) block ^ MAGICWORD;
273 ((char *) &hdr[1])[size] = MAGICBYTE;
274 flood ((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
275 return (__ptr_t) (hdr + 1);
279 reallochook (__ptr_t ptr, __malloc_size_t size, const __ptr_t caller)
283 freehook (ptr, caller);
288 __malloc_size_t osize;
293 if (size > ~((size_t) 0) - (sizeof (struct hdr) + 1))
295 __set_errno (ENOMEM);
301 hdr = ((struct hdr *) ptr) - 1;
307 flood ((char *) ptr + size, FREEFLOOD, osize - size);
314 __free_hook = old_free_hook;
315 __malloc_hook = old_malloc_hook;
316 __memalign_hook = old_memalign_hook;
317 __realloc_hook = old_realloc_hook;
318 if (old_realloc_hook != NULL)
319 hdr = (struct hdr *) (*old_realloc_hook) ((__ptr_t) hdr,
320 sizeof (struct hdr) + size + 1,
323 hdr = (struct hdr *) realloc ((__ptr_t) hdr,
324 sizeof (struct hdr) + size + 1);
325 __free_hook = freehook;
326 __malloc_hook = mallochook;
327 __memalign_hook = memalignhook;
328 __realloc_hook = reallochook;
335 hdr->magic2 = (uintptr_t) hdr ^ MAGICWORD;
336 ((char *) &hdr[1])[size] = MAGICBYTE;
338 flood ((char *) (hdr + 1) + osize, MALLOCFLOOD, size - osize);
339 return (__ptr_t) (hdr + 1);
342 __attribute__ ((noreturn))
344 mabort (enum mcheck_status status)
350 msg = _("memory is consistent, library is buggy\n");
353 msg = _("memory clobbered before allocated block\n");
356 msg = _("memory clobbered past end of allocated block\n");
359 msg = _("block freed twice\n");
362 msg = _("bogus mcheck_status, library is buggy\n");
368 fprintf (stderr, "mcheck: %s", msg);
376 void (*func) (enum mcheck_status);
378 abortfunc = (func != NULL) ? func : &mabort;
380 /* These hooks may not be safely inserted if malloc is already in use. */
381 if (__malloc_initialized <= 0 && !mcheck_used)
383 /* We call malloc() once here to ensure it is initialized. */
384 void *p = malloc (0);
387 old_free_hook = __free_hook;
388 __free_hook = freehook;
389 old_malloc_hook = __malloc_hook;
390 __malloc_hook = mallochook;
391 old_memalign_hook = __memalign_hook;
392 __memalign_hook = memalignhook;
393 old_realloc_hook = __realloc_hook;
394 __realloc_hook = reallochook;
398 return mcheck_used ? 0 : -1;
401 libc_hidden_def (mcheck)
405 mcheck_pedantic (func)
406 void (*func) (enum mcheck_status);
408 int res = mcheck (func);
417 return mcheck_used ? checkhdr (((struct hdr *) ptr) - 1) : MCHECK_DISABLED;