1 e9e18b5e 2022-03-19 op /*	$OpenBSD: recallocarray.c,v 1.2 2021/03/18 11:16:58 claudio Exp $	*/
 2 8f01fac2 2021-03-12 op /*
 3 8f01fac2 2021-03-12 op  * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net>
 4 8f01fac2 2021-03-12 op  *
 5 8f01fac2 2021-03-12 op  * Permission to use, copy, modify, and distribute this software for any
 6 8f01fac2 2021-03-12 op  * purpose with or without fee is hereby granted, provided that the above
 7 8f01fac2 2021-03-12 op  * copyright notice and this permission notice appear in all copies.
 8 8f01fac2 2021-03-12 op  *
 9 8f01fac2 2021-03-12 op  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 8f01fac2 2021-03-12 op  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 8f01fac2 2021-03-12 op  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 8f01fac2 2021-03-12 op  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 8f01fac2 2021-03-12 op  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 8f01fac2 2021-03-12 op  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 8f01fac2 2021-03-12 op  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 8f01fac2 2021-03-12 op  */
17 8f01fac2 2021-03-12 op 
18 8f01fac2 2021-03-12 op #include "compat.h"
19 8f01fac2 2021-03-12 op 
20 8f01fac2 2021-03-12 op #include <errno.h>
21 8f01fac2 2021-03-12 op #include <stdlib.h>
22 8f01fac2 2021-03-12 op #include <stdint.h>
23 8f01fac2 2021-03-12 op #include <string.h>
24 8f01fac2 2021-03-12 op #include <unistd.h>
25 8f01fac2 2021-03-12 op 
26 8f01fac2 2021-03-12 op /*
27 8f01fac2 2021-03-12 op  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
28 8f01fac2 2021-03-12 op  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
29 8f01fac2 2021-03-12 op  */
30 8f01fac2 2021-03-12 op #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
31 8f01fac2 2021-03-12 op 
32 8f01fac2 2021-03-12 op /*
33 8f01fac2 2021-03-12 op  * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
34 8f01fac2 2021-03-12 op  * macros have very poor portability.  Since we only use this
35 8f01fac2 2021-03-12 op  * to avoid free() overhead for small shrinking, simply pick
36 8f01fac2 2021-03-12 op  * an arbitrary number.
37 8f01fac2 2021-03-12 op  */
38 8f01fac2 2021-03-12 op #define getpagesize()	(1UL << 12)
39 8f01fac2 2021-03-12 op 
40 8f01fac2 2021-03-12 op void *
41 8f01fac2 2021-03-12 op recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
42 8f01fac2 2021-03-12 op {
43 8f01fac2 2021-03-12 op 	size_t oldsize, newsize;
44 8f01fac2 2021-03-12 op 	void *newptr;
45 8f01fac2 2021-03-12 op 
46 8f01fac2 2021-03-12 op 	if (ptr == NULL)
47 8f01fac2 2021-03-12 op 		return calloc(newnmemb, size);
48 8f01fac2 2021-03-12 op 
49 8f01fac2 2021-03-12 op 	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
50 8f01fac2 2021-03-12 op 	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
51 8f01fac2 2021-03-12 op 		errno = ENOMEM;
52 8f01fac2 2021-03-12 op 		return NULL;
53 8f01fac2 2021-03-12 op 	}
54 8f01fac2 2021-03-12 op 	newsize = newnmemb * size;
55 8f01fac2 2021-03-12 op 
56 8f01fac2 2021-03-12 op 	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
57 8f01fac2 2021-03-12 op 	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
58 8f01fac2 2021-03-12 op 		errno = EINVAL;
59 8f01fac2 2021-03-12 op 		return NULL;
60 8f01fac2 2021-03-12 op 	}
61 8f01fac2 2021-03-12 op 	oldsize = oldnmemb * size;
62 8f01fac2 2021-03-12 op 
63 8f01fac2 2021-03-12 op 	/*
64 8f01fac2 2021-03-12 op 	 * Don't bother too much if we're shrinking just a bit,
65 8f01fac2 2021-03-12 op 	 * we do not shrink for series of small steps, oh well.
66 8f01fac2 2021-03-12 op 	 */
67 8f01fac2 2021-03-12 op 	if (newsize <= oldsize) {
68 8f01fac2 2021-03-12 op 		size_t d = oldsize - newsize;
69 8f01fac2 2021-03-12 op 
70 e9e18b5e 2022-03-19 op 		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
71 8f01fac2 2021-03-12 op 			memset((char *)ptr + newsize, 0, d);
72 8f01fac2 2021-03-12 op 			return ptr;
73 8f01fac2 2021-03-12 op 		}
74 8f01fac2 2021-03-12 op 	}
75 8f01fac2 2021-03-12 op 
76 8f01fac2 2021-03-12 op 	newptr = malloc(newsize);
77 8f01fac2 2021-03-12 op 	if (newptr == NULL)
78 8f01fac2 2021-03-12 op 		return NULL;
79 8f01fac2 2021-03-12 op 
80 8f01fac2 2021-03-12 op 	if (newsize > oldsize) {
81 8f01fac2 2021-03-12 op 		memcpy(newptr, ptr, oldsize);
82 8f01fac2 2021-03-12 op 		memset((char *)newptr + oldsize, 0, newsize - oldsize);
83 8f01fac2 2021-03-12 op 	} else
84 8f01fac2 2021-03-12 op 		memcpy(newptr, ptr, newsize);
85 8f01fac2 2021-03-12 op 
86 8f01fac2 2021-03-12 op 	explicit_bzero(ptr, oldsize);
87 8f01fac2 2021-03-12 op 	free(ptr);
88 8f01fac2 2021-03-12 op 
89 8f01fac2 2021-03-12 op 	return newptr;
90 8f01fac2 2021-03-12 op }