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 #include "pathmax.h"
  32
  33 #if HAVE_GETCWD
  34 char *getcwd ();
  35 #else
  36 char *getwd ();
  37 # define getcwd(Buf, Max) getwd (Buf)
  38 #endif
  39
  40 extern void *xmalloc ();
  41 extern char *xstrdup ();
  42 extern void free ();
  43
  44 /* Return the current directory, newly allocated, arbitrarily long.
  45    Return NULL and set errno on error. */
  46
  47 char *
  48 xgetcwd ()
  49 {
  50 #if defined __GLIBC__ && __GLIBC__ >= 2
  51   return getcwd (NULL, 0);
  52 #else
  53   char *ret;
  54   unsigned path_max;
  55   char buf[1024];
  56
  57   errno = 0;
  58   ret = getcwd (buf, sizeof (buf));
  59   if (ret != NULL)
  60     return xstrdup (buf);
  61   if (errno != ERANGE)
  62     return NULL;
  63
  64   path_max = 1300;
  65   path_max += 2;                /* The getcwd docs say to do this. */
  66
  67   for (;;)
  68     {
  69       char *cwd = (char *) xmalloc (path_max);
  70
  71       errno = 0;
  72       ret = getcwd (cwd, path_max);
  73       if (ret != NULL)
  74         return ret;
  75       if (errno != ERANGE)
  76         {
  77           int save_errno = errno;
  78           free (cwd);
  79           errno = save_errno;
  80           return NULL;
  81         }
  82
  83       free (cwd);
  84
  85       path_max += path_max / 16;
  86       path_max += 32;
  87     }
  88 #endif
  89 }