1/*	$OpenBSD: reallocarray.c,v 1.2 2014/12/08 03:45:00 bcook 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/cdefs.h>
19__FBSDID("$FreeBSD$");
20
21#include <sys/types.h>
22#include <errno.h>
23#include <stdint.h>
24#include <stdlib.h>
25
26/*
27 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
28 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
29 */
30#define MUL_NO_OVERFLOW	((size_t)1 << (sizeof(size_t) * 4))
31
32void *
33reallocarray(void *optr, size_t nmemb, size_t size)
34{
35
36	if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
37	    nmemb > 0 && SIZE_MAX / nmemb < size) {
38		errno = ENOMEM;
39		return (NULL);
40	}
41	return (realloc(optr, size * nmemb));
42}
43