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      1 /* $NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2015 Joerg Sonnenberger <joerg (at) NetBSD.org>.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  *
     11  * 1. Redistributions of source code must retain the above copyright
     12  *    notice, this list of conditions and the following disclaimer.
     13  * 2. Redistributions in binary form must reproduce the above copyright
     14  *    notice, this list of conditions and the following disclaimer in
     15  *    the documentation and/or other materials provided with the
     16  *    distribution.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
     22  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     23  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
     24  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     27  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     28  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #if HAVE_NBTOOL_CONFIG_H
     33 #include "nbtool_config.h"
     34 #endif
     35 
     36 #include <sys/cdefs.h>
     37 __RCSID("$NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $");
     38 
     39 #include "namespace.h"
     40 #include <errno.h>
     41 /* Old POSIX has SIZE_MAX in limits.h */
     42 #include <limits.h>
     43 #include <stdint.h>
     44 #include <stdlib.h>
     45 #include <string.h>
     46 
     47 #ifdef _LIBC
     48 #ifdef __weak_alias
     49 __weak_alias(reallocarr, _reallocarr)
     50 #endif
     51 #endif
     52 
     53 #define SQRT_SIZE_MAX (((size_t)1) << (sizeof(size_t) * CHAR_BIT / 2))
     54 
     55 #if !HAVE_REALLOCARR
     56 int
     57 reallocarr(void *ptr, size_t number, size_t size)
     58 {
     59 	int saved_errno, result;
     60 	void *optr;
     61 	void *nptr;
     62 
     63 	saved_errno = errno;
     64 	memcpy(&optr, ptr, sizeof(ptr));
     65 	if (number == 0 || size == 0) {
     66 		free(optr);
     67 		nptr = NULL;
     68 		memcpy(ptr, &nptr, sizeof(ptr));
     69 		errno = saved_errno;
     70 		return 0;
     71 	}
     72 
     73 	/*
     74 	 * Try to avoid division here.
     75 	 *
     76 	 * It isn't possible to overflow during multiplication if neither
     77 	 * operand uses any of the most significant half of the bits.
     78 	 */
     79 	if (__predict_false((number|size) >= SQRT_SIZE_MAX &&
     80 	                    number > SIZE_MAX / size)) {
     81 		errno = saved_errno;
     82 		return EOVERFLOW;
     83 	}
     84 
     85 	nptr = realloc(optr, number * size);
     86 	if (__predict_false(nptr == NULL)) {
     87 		result = errno;
     88 	} else {
     89 		result = 0;
     90 		memcpy(ptr, &nptr, sizeof(ptr));
     91 	}
     92 	errno = saved_errno;
     93 	return result;
     94 }
     95 #endif
     96