compat/recallocarray.c

   1 /*      $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $  */
   2 /*
   3  * Copyright (c) 2008, 2017 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 <errno.h>
  19 #include <stdlib.h>
  20 #include <stdint.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23
  24 /*
  25  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
  26  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
  27  */
  28 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
  29
  30 void *
  31 recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
  32 {
  33         size_t oldsize, newsize;
  34         void *newptr;
  35
  36         if (ptr == NULL)
  37                 return calloc(newnmemb, size);
  38
  39         if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
  40             newnmemb > 0 && SIZE_MAX / newnmemb < size) {
  41                 errno = ENOMEM;
  42                 return NULL;
  43         }
  44         newsize = newnmemb * size;
  45
  46         if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
  47             oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
  48                 errno = EINVAL;
  49                 return NULL;
  50         }
  51         oldsize = oldnmemb * size;
  52
  53         /*
  54          * Don't bother too much if we're shrinking just a bit,
  55          * we do not shrink for series of small steps, oh well.
  56          */
  57         if (newsize <= oldsize) {
  58                 size_t d = oldsize - newsize;
  59
  60                 if (d < oldsize / 2 && d < (size_t)getpagesize()) {
  61                         memset((char *)ptr + newsize, 0, d);
  62                         return ptr;
  63                 }
  64         }
  65
  66         newptr = malloc(newsize);
  67         if (newptr == NULL)
  68                 return NULL;
  69
  70         if (newsize > oldsize) {
  71                 memcpy(newptr, ptr, oldsize);
  72                 memset((char *)newptr + oldsize, 0, newsize - oldsize);
  73         } else
  74                 memcpy(newptr, ptr, newsize);
  75
  76 #ifdef __APPLE__
  77         memset_s(ptr, oldsize, 0, oldsize);
  78 #elif defined(__NetBSD__)
  79         explicit_memset(ptr, oldsize, 0);
  80 #else
  81         explicit_bzero(ptr, oldsize);
  82 #endif
  83         free(ptr);
  84
  85         return newptr;
  86 }