1 /*
2  * Copyright (c) 2008 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 #include <sys/types.h>
18 #include <errno.h>
19 #include <stdint.h>
20 #include <stdlib.h>
21 
22 /*
23  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
24  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
25  */
26 #define MUL_NO_OVERFLOW	((size_t)1 << (sizeof(size_t) * 4))
27 
28 void *
29 reallocarray(void *optr, size_t nmemb, size_t size)
30 {
31 	if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
32 	    nmemb > 0 && SIZE_MAX / nmemb < size) {
33 		errno = ENOMEM;
34 		return NULL;
35 	}
36 	return realloc(optr, size * nmemb);
37 }