1/*	$Id: compat_reallocarray.c,v 1.5 2020/06/15 01:37:15 schwarze Exp $ */
2/*	$OpenBSD: reallocarray.c,v 1.3 2015/09/13 08:31:47 guenther Exp $	*/
3/*
4 * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18#include "config.h"
19
20#include <sys/types.h>
21#include <errno.h>
22#include <stdint.h>
23#include <stdlib.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
31void *
32reallocarray(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}
41