1/*	$OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $	*/
2
3/*
4 * Copyright (c) 2008, 2017 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
19/* OPENBSD ORIGINAL: lib/libc/stdlib/recallocarray.c */
20
21#include "includes.h"
22#ifndef HAVE_RECALLOCARRAY
23
24#include <errno.h>
25#include <stdlib.h>
26#ifdef HAVE_STDINT_H
27#include <stdint.h>
28#endif
29#include <string.h>
30#include <unistd.h>
31
32/*
33 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
34 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
35 */
36#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
37
38void *
39recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
40{
41	size_t oldsize, newsize;
42	void *newptr;
43
44	if (ptr == NULL)
45		return calloc(newnmemb, size);
46
47	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
48	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
49		errno = ENOMEM;
50		return NULL;
51	}
52	newsize = newnmemb * size;
53
54	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
55	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
56		errno = EINVAL;
57		return NULL;
58	}
59	oldsize = oldnmemb * size;
60
61	/*
62	 * Don't bother too much if we're shrinking just a bit,
63	 * we do not shrink for series of small steps, oh well.
64	 */
65	if (newsize <= oldsize) {
66		size_t d = oldsize - newsize;
67
68		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
69			memset((char *)ptr + newsize, 0, d);
70			return ptr;
71		}
72	}
73
74	newptr = malloc(newsize);
75	if (newptr == NULL)
76		return NULL;
77
78	if (newsize > oldsize) {
79		memcpy(newptr, ptr, oldsize);
80		memset((char *)newptr + oldsize, 0, newsize - oldsize);
81	} else
82		memcpy(newptr, ptr, newsize);
83
84	explicit_bzero(ptr, oldsize);
85	free(ptr);
86
87	return newptr;
88}
89/* DEF_WEAK(recallocarray); */
90
91#endif /* HAVE_RECALLOCARRAY */
92