compat/reallocarray.c

   1 /*      $OpenBSD: reallocarray.c,v 1.3 2015/09/13 08:31:47 guenther Exp $       */
   2 /*
   3  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 #include <sys/types.h>
  19 #include <errno.h>
  20 #include <stdint.h>
  21 #include <stdlib.h>
  22
  23 #include "compat.h"
  24
  25 /*
  26  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
  27  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
  28  */
  29 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
  30
  31 void *
  32 reallocarray(void *optr, size_t nmemb, size_t size)
  33 {
  34         if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
  35             nmemb > 0 && SIZE_MAX / nmemb < size) {
  36                 errno = ENOMEM;
  37                 return NULL;
  38         }
  39         return realloc(optr, size * nmemb);
  40 }