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
37 void *
recallocarray(void * ptr,size_t oldnmemb,size_t newnmemb,size_t size)38 recallocarray(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