1/* $NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $ */
2
3/*-
4 * Copyright (c) 2015 Joerg Sonnenberger <joerg@NetBSD.org>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
22 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
24 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
26 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
28 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33__RCSID("$NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $");
34
35#include "netcompat.h"
36#include <errno.h>
37/* Old POSIX has SIZE_MAX in limits.h */
38#include <limits.h>
39#include <stdint.h>
40#include <stdlib.h>
41#include <string.h>
42
43#define SQRT_SIZE_MAX (((size_t)1) << (sizeof(size_t) * CHAR_BIT / 2))
44
45int
46reallocarr(void *ptr, size_t number, size_t size)
47{
48 int saved_errno, result;
49 void *optr;
50 void *nptr;
51
52 saved_errno = errno;
53 memcpy(&optr, ptr, sizeof(ptr));
54 if (number == 0 || size == 0) {
55 free(optr);
56 nptr = NULL;
57 memcpy(ptr, &nptr, sizeof(ptr));
58 errno = saved_errno;
59 return 0;
60 }
61
62 /*
63 * Try to avoid division here.
64 *
65 * It isn't possible to overflow during multiplication if neither
66 * operand uses any of the most significant half of the bits.
67 */
68 if (__predict_false((number|size) >= SQRT_SIZE_MAX &&
69 number > SIZE_MAX / size)) {
70 errno = saved_errno;
71 return EOVERFLOW;
72 }
73
74 nptr = realloc(optr, number * size);
75 if (__predict_false(nptr == NULL)) {
76 result = errno;
77 } else {
78 result = 0;
79 memcpy(ptr, &nptr, sizeof(ptr));
80 }
81 errno = saved_errno;
82 return result;
83}
