gl/realloc.c

   1 /* realloc() function that is glibc compatible.
   2
   3    Copyright (C) 1997, 2003, 2004, 2006, 2007 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 /* written by Jim Meyering and Bruno Haible */
  19
  20 #include <config.h>
  21
  22 /* Only the AC_FUNC_REALLOC macro defines 'realloc' already in config.h.  */
  23 #ifdef realloc
  24 # define NEED_REALLOC_GNU 1
  25 #endif
  26
  27 /* Infer the properties of the system's malloc function.
  28    Only the AC_FUNC_MALLOC macro defines 'malloc' already in config.h.  */
  29 #if GNULIB_MALLOC_GNU && !defined malloc
  30 # define SYSTEM_MALLOC_GLIBC_COMPATIBLE 1
  31 #endif
  32
  33 /* Below we want to call the system's malloc and realloc.
  34    Undefine the symbols here so that including <stdlib.h> provides a
  35    declaration of malloc(), not of rpl_malloc(), and likewise for realloc.  */
  36 #undef malloc
  37 #undef realloc
  38
  39 /* Specification.  */
  40 #include <stdlib.h>
  41
  42 #include <errno.h>
  43
  44 /* Below we want to call the system's malloc and realloc.
  45    Undefine the symbols, if they were defined by gnulib's <stdlib.h>
  46    replacement.  */
  47 #undef malloc
  48 #undef realloc
  49
  50 /* Change the size of an allocated block of memory P to N bytes,
  51    with error checking.  If N is zero, change it to 1.  If P is NULL,
  52    use malloc.  */
  53
  54 void *
  55 rpl_realloc (void *p, size_t n)
  56 {
  57   void *result;
  58
  59 #if NEED_REALLOC_GNU
  60   if (n == 0)
  61     {
  62       n = 1;
  63
  64       /* In theory realloc might fail, so don't rely on it to free.  */
  65       free (p);
  66       p = NULL;
  67     }
  68 #endif
  69
  70   if (p == NULL)
  71     {
  72 #if GNULIB_REALLOC_GNU && !NEED_REALLOC_GNU && !SYSTEM_MALLOC_GLIBC_COMPATIBLE
  73       if (n == 0)
  74         n = 1;
  75 #endif
  76       result = malloc (n);
  77     }
  78   else
  79     result = realloc (p, n);
  80
  81 #if !HAVE_REALLOC_POSIX
  82   if (result == NULL)
  83     errno = ENOMEM;
  84 #endif
  85
  86   return result;
  87 }