1 c7949fd5 2022-03-19 op /*	$OpenBSD: recallocarray.c,v 1.2 2021/03/18 11:16:58 claudio Exp $	*/
 2 5c342d05 2021-01-21 op /*
 3 5c342d05 2021-01-21 op  * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net>
 4 5c342d05 2021-01-21 op  *
 5 5c342d05 2021-01-21 op  * Permission to use, copy, modify, and distribute this software for any
 6 5c342d05 2021-01-21 op  * purpose with or without fee is hereby granted, provided that the above
 7 5c342d05 2021-01-21 op  * copyright notice and this permission notice appear in all copies.
 8 5c342d05 2021-01-21 op  *
 9 5c342d05 2021-01-21 op  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 5c342d05 2021-01-21 op  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 5c342d05 2021-01-21 op  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 5c342d05 2021-01-21 op  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 5c342d05 2021-01-21 op  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 5c342d05 2021-01-21 op  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 5c342d05 2021-01-21 op  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 5c342d05 2021-01-21 op  */
17 5c342d05 2021-01-21 op 
18 76898714 2021-02-12 op #include "../config.h"
19 76898714 2021-02-12 op 
20 5c342d05 2021-01-21 op #include <errno.h>
21 5c342d05 2021-01-21 op #include <stdlib.h>
22 5c342d05 2021-01-21 op #include <stdint.h>
23 5c342d05 2021-01-21 op #include <string.h>
24 5c342d05 2021-01-21 op #include <unistd.h>
25 5c342d05 2021-01-21 op 
26 5c342d05 2021-01-21 op /*
27 5c342d05 2021-01-21 op  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
28 5c342d05 2021-01-21 op  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
29 5c342d05 2021-01-21 op  */
30 5c342d05 2021-01-21 op #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
31 5c342d05 2021-01-21 op 
32 5c342d05 2021-01-21 op /*
33 5c342d05 2021-01-21 op  * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
34 5c342d05 2021-01-21 op  * macros have very poor portability.  Since we only use this
35 5c342d05 2021-01-21 op  * to avoid free() overhead for small shrinking, simply pick
36 5c342d05 2021-01-21 op  * an arbitrary number.
37 5c342d05 2021-01-21 op  */
38 5c342d05 2021-01-21 op #define getpagesize()	(1UL << 12)
39 5c342d05 2021-01-21 op 
40 5c342d05 2021-01-21 op void *
41 5c342d05 2021-01-21 op recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
42 5c342d05 2021-01-21 op {
43 5c342d05 2021-01-21 op 	size_t oldsize, newsize;
44 5c342d05 2021-01-21 op 	void *newptr;
45 5c342d05 2021-01-21 op 
46 5c342d05 2021-01-21 op 	if (ptr == NULL)
47 5c342d05 2021-01-21 op 		return calloc(newnmemb, size);
48 5c342d05 2021-01-21 op 
49 5c342d05 2021-01-21 op 	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
50 5c342d05 2021-01-21 op 	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
51 5c342d05 2021-01-21 op 		errno = ENOMEM;
52 5c342d05 2021-01-21 op 		return NULL;
53 5c342d05 2021-01-21 op 	}
54 5c342d05 2021-01-21 op 	newsize = newnmemb * size;
55 5c342d05 2021-01-21 op 
56 5c342d05 2021-01-21 op 	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
57 5c342d05 2021-01-21 op 	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
58 5c342d05 2021-01-21 op 		errno = EINVAL;
59 5c342d05 2021-01-21 op 		return NULL;
60 5c342d05 2021-01-21 op 	}
61 5c342d05 2021-01-21 op 	oldsize = oldnmemb * size;
62 5c342d05 2021-01-21 op 
63 5c342d05 2021-01-21 op 	/*
64 5c342d05 2021-01-21 op 	 * Don't bother too much if we're shrinking just a bit,
65 5c342d05 2021-01-21 op 	 * we do not shrink for series of small steps, oh well.
66 5c342d05 2021-01-21 op 	 */
67 5c342d05 2021-01-21 op 	if (newsize <= oldsize) {
68 5c342d05 2021-01-21 op 		size_t d = oldsize - newsize;
69 5c342d05 2021-01-21 op 
70 c7949fd5 2022-03-19 op 		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
71 5c342d05 2021-01-21 op 			memset((char *)ptr + newsize, 0, d);
72 5c342d05 2021-01-21 op 			return ptr;
73 5c342d05 2021-01-21 op 		}
74 5c342d05 2021-01-21 op 	}
75 5c342d05 2021-01-21 op 
76 5c342d05 2021-01-21 op 	newptr = malloc(newsize);
77 5c342d05 2021-01-21 op 	if (newptr == NULL)
78 5c342d05 2021-01-21 op 		return NULL;
79 5c342d05 2021-01-21 op 
80 5c342d05 2021-01-21 op 	if (newsize > oldsize) {
81 5c342d05 2021-01-21 op 		memcpy(newptr, ptr, oldsize);
82 5c342d05 2021-01-21 op 		memset((char *)newptr + oldsize, 0, newsize - oldsize);
83 5c342d05 2021-01-21 op 	} else
84 5c342d05 2021-01-21 op 		memcpy(newptr, ptr, newsize);
85 5c342d05 2021-01-21 op 
86 5c342d05 2021-01-21 op 	explicit_bzero(ptr, oldsize);
87 5c342d05 2021-01-21 op 	free(ptr);
88 5c342d05 2021-01-21 op 
89 5c342d05 2021-01-21 op 	return newptr;
90 5c342d05 2021-01-21 op }