9 /* $Id: compat_recallocarray.c,v 1.1 2017/06/12 19:05:47 schwarze Exp $ */
10 /* $OpenBSD: malloc.c,v 1.225 2017/05/13 07:11:29 otto Exp $ */
12 * Copyright (c) 2017 Otto Moerbeek <otto@drijf.net>
14 * Permission to use, copy, modify, and distribute this software for any
15 * purpose with or without fee is hereby granted, provided that the above
16 * copyright notice and this permission notice appear in all copies.
18 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
19 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
20 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
21 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
22 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
23 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
24 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
27 #include <sys/types.h>
34 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
35 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
37 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
40 * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
41 * macros have very poor portability. Since we only use this
42 * to avoid free() overhead for small shrinking, simply pick
43 * an arbitrary number.
45 #define MALLOC_PAGESIZE (1UL << 12)
49 recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
51 size_t oldsize, newsize;
55 return calloc(newnmemb, size);
57 if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
58 newnmemb > 0 && SIZE_MAX / newnmemb < size) {
62 newsize = newnmemb * size;
64 if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
65 oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
69 oldsize = oldnmemb * size;
72 * Don't bother too much if we're shrinking just a bit,
73 * we do not shrink for series of small steps, oh well.
75 if (newsize <= oldsize) {
76 size_t d = oldsize - newsize;
78 if (d < oldsize / 2 && d < MALLOC_PAGESIZE) {
79 memset((char *)ptr + newsize, 0, d);
84 newptr = malloc(newsize);
88 if (newsize > oldsize) {
89 memcpy(newptr, ptr, oldsize);
90 memset((char *)newptr + oldsize, 0, newsize - oldsize);
92 memcpy(newptr, ptr, newsize);
95 * At this point, the OpenBSD implementation calls
96 * explicit_bzero() on the old memory before it is
97 * freed. Since explicit_bzero() is hard to implement
98 * portably and we don't handle confidential data in
99 * mandoc in the first place, simply free the memory
100 * without clearing it.
108 #endif /* !HAVE_RECALLOCARRAY */