reallocarray.c revision 1.6 
1/*	$NetBSD: reallocarray.c,v 1.6 2016/04/05 15:01:26 roy Exp $	*/
2/*	$OpenBSD: reallocarray.c,v 1.1 2014/05/08 21:43:49 deraadt Exp $	*/
3
4/*-
5 * Copyright (c) 2015 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Christos Zoulas.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30 * POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/cdefs.h>
34__RCSID("$NetBSD: reallocarray.c,v 1.6 2016/04/05 15:01:26 roy Exp $");
35
36#define _OPENBSD_SOURCE
37#include <errno.h>
38#include <limits.h>
39#include <stdlib.h>
40
41#define SQRT_SIZE_MAX (((size_t)1) << (sizeof(size_t) * CHAR_BIT / 2))
42void *
43reallocarray(void *optr, size_t nmemb, size_t size)
44{
45
46	/*
47	 * Try to avoid division here.
48	 *
49	 * It isn't possible to overflow during multiplication if neither
50	 * operand uses any of the most significant half of the bits.
51	 */
52	if (__predict_false((nmemb | size) >= SQRT_SIZE_MAX &&
53			    nmemb > SIZE_MAX / size))
54	{
55		errno = EOVERFLOW;
56		return NULL;
57	}
58	return realloc(optr, nmemb * size);
59}
60