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