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1 /*	$OpenBSD: reallocarray.c,v 1.1 2014/05/08 21:43:49 deraadt Exp $	*/
2 /*
3  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <errno.h>
20 #include <stdint.h>
21 #include <stdlib.h>
22 
23 /*
24  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
25  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
26  */
27 #define MUL_NO_OVERFLOW	((size_t)1 << (sizeof(size_t) * 4))
28 
29 void *
reallocarray(void * optr,size_t nmemb,size_t size)30 reallocarray(void *optr, size_t nmemb, size_t size)
31 {
32 	if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
33 	    nmemb > 0 && SIZE_MAX / nmemb < size) {
34 		errno = ENOMEM;
35 		return NULL;
36 	}
37 	return realloc(optr, size * nmemb);
38 }
39