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