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