1/*	$OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $	*/
2/*
3 * Copyright (c) 2008, 2017 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/* OPENBSD ORIGINAL: lib/libc/stdlib/recallocarray.c */
19
20#include "includes.h"
21#ifndef HAVE_RECALLOCARRAY
22
23#include <errno.h>
24#include <stdlib.h>
25#ifdef HAVE_STDINT_H
26#include <stdint.h>
27#endif
28#include <string.h>
29#include <unistd.h>
30
31/*
32 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
33 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
34 */
35#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
36
37void *
38recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
39{
40	size_t oldsize, newsize;
41	void *newptr;
42
43	if (ptr == NULL)
44		return calloc(newnmemb, size);
45
46	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
47	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
48		errno = ENOMEM;
49		return NULL;
50	}
51	newsize = newnmemb * size;
52
53	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
54	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
55		errno = EINVAL;
56		return NULL;
57	}
58	oldsize = oldnmemb * size;
59
60	/*
61	 * Don't bother too much if we're shrinking just a bit,
62	 * we do not shrink for series of small steps, oh well.
63	 */
64	if (newsize <= oldsize) {
65		size_t d = oldsize - newsize;
66
67		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
68			memset((char *)ptr + newsize, 0, d);
69			return ptr;
70		}
71	}
72
73	newptr = malloc(newsize);
74	if (newptr == NULL)
75		return NULL;
76
77	if (newsize > oldsize) {
78		memcpy(newptr, ptr, oldsize);
79		memset((char *)newptr + oldsize, 0, newsize - oldsize);
80	} else
81		memcpy(newptr, ptr, newsize);
82
83	explicit_bzero(ptr, oldsize);
84	free(ptr);
85
86	return newptr;
87}
88/* DEF_WEAK(recallocarray); */
89
90#endif /* HAVE_RECALLOCARRAY */
91