gl/realloc.c

   1 /* realloc() function that is glibc compatible.
   2
   3    Copyright (C) 1997, 2003-2004, 2006-2007, 2009-2010 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software: you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* written by Jim Meyering and Bruno Haible */
  20
  21 #include <config.h>
  22
  23 /* Only the AC_FUNC_REALLOC macro defines 'realloc' already in config.h.  */
  24 #ifdef realloc
  25 # define NEED_REALLOC_GNU 1
  26 #endif
  27
  28 /* Infer the properties of the system's malloc function.
  29    Only the AC_FUNC_MALLOC macro defines 'malloc' already in config.h.  */
  30 #if GNULIB_MALLOC_GNU && !defined malloc
  31 # define SYSTEM_MALLOC_GLIBC_COMPATIBLE 1
  32 #endif
  33
  34 /* Below we want to call the system's malloc and realloc.
  35    Undefine the symbols here so that including <stdlib.h> provides a
  36    declaration of malloc(), not of rpl_malloc(), and likewise for realloc.  */
  37 #undef malloc
  38 #undef realloc
  39
  40 /* Specification.  */
  41 #include <stdlib.h>
  42
  43 #include <errno.h>
  44
  45 /* Below we want to call the system's malloc and realloc.
  46    Undefine the symbols, if they were defined by gnulib's <stdlib.h>
  47    replacement.  */
  48 #undef malloc
  49 #undef realloc
  50
  51 /* Change the size of an allocated block of memory P to N bytes,
  52    with error checking.  If N is zero, change it to 1.  If P is NULL,
  53    use malloc.  */
  54
  55 void *
  56 rpl_realloc (void *p, size_t n)
  57 {
  58   void *result;
  59
  60 #if NEED_REALLOC_GNU
  61   if (n == 0)
  62     {
  63       n = 1;
  64
  65       /* In theory realloc might fail, so don't rely on it to free.  */
  66       free (p);
  67       p = NULL;
  68     }
  69 #endif
  70
  71   if (p == NULL)
  72     {
  73 #if GNULIB_REALLOC_GNU && !NEED_REALLOC_GNU && !SYSTEM_MALLOC_GLIBC_COMPATIBLE
  74       if (n == 0)
  75         n = 1;
  76 #endif
  77       result = malloc (n);
  78     }
  79   else
  80     result = realloc (p, n);
  81
  82 #if !HAVE_REALLOC_POSIX
  83   if (result == NULL)
  84     errno = ENOMEM;
  85 #endif
  86
  87   return result;
  88 }