1 014c66b6 2023-06-25 op /*	$OpenBSD: recallocarray.c,v 1.2 2021/03/18 11:16:58 claudio Exp $	*/
 2 014c66b6 2023-06-25 op /*
 3 014c66b6 2023-06-25 op  * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net>
 4 014c66b6 2023-06-25 op  *
 5 014c66b6 2023-06-25 op  * Permission to use, copy, modify, and distribute this software for any
 6 014c66b6 2023-06-25 op  * purpose with or without fee is hereby granted, provided that the above
 7 014c66b6 2023-06-25 op  * copyright notice and this permission notice appear in all copies.
 8 014c66b6 2023-06-25 op  *
 9 014c66b6 2023-06-25 op  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 014c66b6 2023-06-25 op  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 014c66b6 2023-06-25 op  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 014c66b6 2023-06-25 op  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 014c66b6 2023-06-25 op  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 014c66b6 2023-06-25 op  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 014c66b6 2023-06-25 op  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 014c66b6 2023-06-25 op  */
17 014c66b6 2023-06-25 op 
18 014c66b6 2023-06-25 op #include <errno.h>
19 014c66b6 2023-06-25 op #include <stdlib.h>
20 014c66b6 2023-06-25 op #include <stdint.h>
21 014c66b6 2023-06-25 op #include <string.h>
22 014c66b6 2023-06-25 op #include <unistd.h>
23 014c66b6 2023-06-25 op 
24 014c66b6 2023-06-25 op /*
25 014c66b6 2023-06-25 op  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
26 014c66b6 2023-06-25 op  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
27 014c66b6 2023-06-25 op  */
28 014c66b6 2023-06-25 op #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
29 014c66b6 2023-06-25 op 
30 014c66b6 2023-06-25 op /*
31 014c66b6 2023-06-25 op  * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
32 014c66b6 2023-06-25 op  * macros have very poor portability.  Since we only use this
33 014c66b6 2023-06-25 op  * to avoid free() overhead for small shrinking, simply pick
34 014c66b6 2023-06-25 op  * an arbitrary number.
35 014c66b6 2023-06-25 op  */
36 014c66b6 2023-06-25 op #define getpagesize()	(1UL << 12)
37 014c66b6 2023-06-25 op 
38 014c66b6 2023-06-25 op void *
39 014c66b6 2023-06-25 op recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
40 014c66b6 2023-06-25 op {
41 014c66b6 2023-06-25 op 	size_t oldsize, newsize;
42 014c66b6 2023-06-25 op 	void *newptr;
43 014c66b6 2023-06-25 op 
44 014c66b6 2023-06-25 op 	if (ptr == NULL)
45 014c66b6 2023-06-25 op 		return calloc(newnmemb, size);
46 014c66b6 2023-06-25 op 
47 014c66b6 2023-06-25 op 	if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
48 014c66b6 2023-06-25 op 	    newnmemb > 0 && SIZE_MAX / newnmemb < size) {
49 014c66b6 2023-06-25 op 		errno = ENOMEM;
50 014c66b6 2023-06-25 op 		return NULL;
51 014c66b6 2023-06-25 op 	}
52 014c66b6 2023-06-25 op 	newsize = newnmemb * size;
53 014c66b6 2023-06-25 op 
54 014c66b6 2023-06-25 op 	if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
55 014c66b6 2023-06-25 op 	    oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
56 014c66b6 2023-06-25 op 		errno = EINVAL;
57 014c66b6 2023-06-25 op 		return NULL;
58 014c66b6 2023-06-25 op 	}
59 014c66b6 2023-06-25 op 	oldsize = oldnmemb * size;
60 014c66b6 2023-06-25 op 
61 014c66b6 2023-06-25 op 	/*
62 014c66b6 2023-06-25 op 	 * Don't bother too much if we're shrinking just a bit,
63 014c66b6 2023-06-25 op 	 * we do not shrink for series of small steps, oh well.
64 014c66b6 2023-06-25 op 	 */
65 014c66b6 2023-06-25 op 	if (newsize <= oldsize) {
66 014c66b6 2023-06-25 op 		size_t d = oldsize - newsize;
67 014c66b6 2023-06-25 op 
68 014c66b6 2023-06-25 op 		if (d < oldsize / 2 && d < (size_t)getpagesize()) {
69 014c66b6 2023-06-25 op 			memset((char *)ptr + newsize, 0, d);
70 014c66b6 2023-06-25 op 			return ptr;
71 014c66b6 2023-06-25 op 		}
72 014c66b6 2023-06-25 op 	}
73 014c66b6 2023-06-25 op 
74 014c66b6 2023-06-25 op 	newptr = malloc(newsize);
75 014c66b6 2023-06-25 op 	if (newptr == NULL)
76 014c66b6 2023-06-25 op 		return NULL;
77 014c66b6 2023-06-25 op 
78 014c66b6 2023-06-25 op 	if (newsize > oldsize) {
79 014c66b6 2023-06-25 op 		memcpy(newptr, ptr, oldsize);
80 014c66b6 2023-06-25 op 		memset((char *)newptr + oldsize, 0, newsize - oldsize);
81 014c66b6 2023-06-25 op 	} else
82 014c66b6 2023-06-25 op 		memcpy(newptr, ptr, newsize);
83 014c66b6 2023-06-25 op 
84 014c66b6 2023-06-25 op 	explicit_bzero(ptr, oldsize);
85 014c66b6 2023-06-25 op 	free(ptr);
86 014c66b6 2023-06-25 op 
87 014c66b6 2023-06-25 op 	return newptr;
88 014c66b6 2023-06-25 op }