Dogcows Code - chaz/tar/blob - lib/xgetcwd.c

   1 /* xgetcwd.c -- return current directory with unlimited length
   2    Copyright (C) 1992, 1996, 2000, 2001 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */
  19
  20 #if HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include <errno.h>
  26 #ifndef errno
  27 extern int errno;
  28 #endif
  29
  30 #include <sys/types.h>
  31
  32 #if HAVE_STDLIB_H
  33 # include <stdlib.h>
  34 #endif
  35 #if HAVE_UNISTD_H
  36 # include <unistd.h>
  37 #endif
  38
  39 #if HAVE_GETCWD
  40 char *getcwd ();
  41 #else
  42 char *getwd ();
  43 # define getcwd(Buf, Max) getwd (Buf)
  44 #endif
  45
  46 #include "xalloc.h"
  47
  48 /* Return the current directory, newly allocated, arbitrarily long.
  49    Return NULL and set errno on error. */
  50
  51 char *
  52 xgetcwd ()
  53 {
  54 #if defined __GLIBC__ && __GLIBC__ >= 2
  55   return getcwd (NULL, 0);
  56 #else
  57   char *ret;
  58   size_t path_max;
  59   char buf[1024];
  60
  61   errno = 0;
  62   ret = getcwd (buf, sizeof (buf));
  63   if (ret != NULL)
  64     return xstrdup (buf);
  65   if (errno != ERANGE)
  66     return NULL;
  67
  68   path_max = 1 << 10;
  69
  70   for (;;)
  71     {
  72       char *cwd = (char *) xmalloc (path_max);
  73       int save_errno;
  74
  75       errno = 0;
  76       ret = getcwd (cwd, path_max);
  77       if (ret != NULL)
  78         return ret;
  79       save_errno = errno;
  80       free (cwd);
  81       if (save_errno != ERANGE)
  82         {
  83           errno = save_errno;
  84           return NULL;
  85         }
  86
  87       path_max *= 2;
  88       if (path_max == 0)
  89         xalloc_die ();
  90     }
  91 #endif
  92 }