lib/libc/stdlib/reallocarr.c

   1 /* $NetBSD: reallocarr.c,v 1.5 2015/08/20 22:27:49 kamil Exp $ */
   2
   3 /*-
   4  * Copyright (c) 2015 Joerg Sonnenberger <joerg@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