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@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
35char *getcwd ();
36# endif
37#else
38char *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
47char *
48xgetcwd ()
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