Annotation of mandoc/compat_recallocarray.c, Revision 1.2
1.2 ! schwarze 1: /* $Id: compat_recallocarray.c,v 1.1 2017/06/12 19:05:47 schwarze Exp $ */
! 2: /* $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $ */
1.1 schwarze 3: /*
1.2 ! schwarze 4: * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net>
1.1 schwarze 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: */
1.2 ! schwarze 18: #include "config.h"
1.1 schwarze 19:
20: #include <sys/types.h>
21: #include <errno.h>
1.2 ! schwarze 22: #include <stdlib.h>
1.1 schwarze 23: #include <stdint.h>
24: #include <string.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: */
1.2 ! schwarze 30: #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
1.1 schwarze 31:
32: /*
33: * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
34: * macros have very poor portability. Since we only use this
35: * to avoid free() overhead for small shrinking, simply pick
36: * an arbitrary number.
37: */
1.2 ! schwarze 38: #define getpagesize() (1UL << 12)
1.1 schwarze 39:
40:
41: void *
42: recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
43: {
44: size_t oldsize, newsize;
45: void *newptr;
46:
47: if (ptr == NULL)
48: return calloc(newnmemb, size);
49:
50: if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
51: newnmemb > 0 && SIZE_MAX / newnmemb < size) {
52: errno = ENOMEM;
53: return NULL;
54: }
55: newsize = newnmemb * size;
56:
57: if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
58: oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
59: errno = EINVAL;
60: return NULL;
61: }
62: oldsize = oldnmemb * size;
63:
64: /*
65: * Don't bother too much if we're shrinking just a bit,
66: * we do not shrink for series of small steps, oh well.
67: */
68: if (newsize <= oldsize) {
69: size_t d = oldsize - newsize;
70:
1.2 ! schwarze 71: if (d < oldsize / 2 && d < getpagesize()) {
1.1 schwarze 72: memset((char *)ptr + newsize, 0, d);
73: return ptr;
74: }
75: }
76:
77: newptr = malloc(newsize);
78: if (newptr == NULL)
79: return NULL;
80:
81: if (newsize > oldsize) {
82: memcpy(newptr, ptr, oldsize);
83: memset((char *)newptr + oldsize, 0, newsize - oldsize);
84: } else
85: memcpy(newptr, ptr, newsize);
86:
87: /*
88: * At this point, the OpenBSD implementation calls
89: * explicit_bzero() on the old memory before it is
90: * freed. Since explicit_bzero() is hard to implement
91: * portably and we don't handle confidential data in
92: * mandoc in the first place, simply free the memory
93: * without clearing it.
94: */
95:
96: free(ptr);
97:
98: return newptr;
99: }
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