reallocarray.c revision 1.2 
1/*	$OpenBSD: reallocarray.c,v 1.1 2014/05/08 21:43:49 deraadt 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#define _OPENBSD_SOURCE
18#include <sys/cdefs.h>
19__RCSID("$NetBSD: reallocarray.c,v 1.2 2015/02/17 20:33:40 joerg Exp $");
20
21#include <sys/param.h>
22#include <sys/types.h>
23#include <errno.h>
24#include <stdint.h>
25#include <stdlib.h>
26
27/*
28 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
29 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
30 */
31#define MUL_NO_OVERFLOW	((size_t)1 << (sizeof(size_t) * (CHAR_BIT / 2)))
32
33void *
34reallocarray(void *optr, size_t nmemb, size_t size)
35{
36	if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
37	    size > 0 && nmemb > 0 && SIZE_MAX / nmemb < size) {
38		errno = ENOMEM;
39		return NULL;
40	}
41	return realloc(optr, size * nmemb);
42}
43