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      1 /* xgetcwd.c -- return current directory with unlimited length
      2    Copyright (C) 1992, 1996, 2000, 2003, 2005-2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
     17 
     18 /* Written by David MacKenzie <djm (at) gnu.ai.mit.edu>.  */
     19 
     20 #include <config.h>
     21 
     22 #include <stdlib.h>
     23 #include <stdio.h>
     24 #include <errno.h>
     25 #include <sys/types.h>
     26 #include <unistd.h>
     27 
     28 #include "pathmax.h"
     29 
     30 #if HAVE_GETCWD
     31 # ifdef VMS
     32    /* We want the directory in Unix syntax, not in VMS syntax.  */
     33 #  define getcwd(Buf, Max) (getcwd) (Buf, Max, 0)
     34 # else
     35 char *getcwd ();
     36 # endif
     37 #else
     38 char *getwd ();
     39 # define getcwd(Buf, Max) getwd (Buf)
     40 #endif
     41 
     42 #include "xalloc.h"
     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   char *ret;
     51   unsigned path_max;
     52   char buf[1024];
     53 
     54   errno = 0;
     55   ret = getcwd (buf, sizeof (buf));
     56   if (ret != NULL)
     57     return xstrdup (buf);
     58   if (errno != ERANGE)
     59     return NULL;
     60 
     61   path_max = (unsigned) PATH_MAX;
     62   path_max += 2;		/* The getcwd docs say to do this. */
     63 
     64   for (;;)
     65     {
     66       char *cwd = (char *) xmalloc (path_max);
     67 
     68       errno = 0;
     69       ret = getcwd (cwd, path_max);
     70       if (ret != NULL)
     71 	return ret;
     72       if (errno != ERANGE)
     73 	{
     74 	  int save_errno = errno;
     75 	  free (cwd);
     76 	  errno = save_errno;
     77 	  return NULL;
     78 	}
     79 
     80       free (cwd);
     81 
     82       path_max += path_max / 16;
     83       path_max += 32;
     84     }
     85 }
     86