1 /* xgetcwd.c -- return current directory with unlimited length
2 Copyright (C) 1992, 1996, 2000, 2003, 2005-2006, 2011 Free
3 Software Foundation, Inc.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
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 /* In this file, PATH_MAX is the size of an initial memory allocation. */
31 #ifndef PATH_MAX
32 # define PATH_MAX 8192
33 #endif
34
35 #if HAVE_GETCWD
36 # ifdef VMS
37 /* We want the directory in Unix syntax, not in VMS syntax. */
38 # define getcwd(Buf, Max) (getcwd) (Buf, Max, 0)
39 # else
40 char *getcwd ();
41 # endif
42 #else
43 char *getwd ();
44 # define getcwd(Buf, Max) getwd (Buf)
45 #endif
46
47 #include "xalloc.h"
48
49 /* Return the current directory, newly allocated, arbitrarily long.
50 Return NULL and set errno on error. */
51
52 char *
xgetcwd()53 xgetcwd ()
54 {
55 char *ret;
56 unsigned path_max;
57 char buf[1024];
58
59 errno = 0;
60 ret = getcwd (buf, sizeof (buf));
61 if (ret != NULL)
62 return xstrdup (buf);
63 if (errno != ERANGE)
64 return NULL;
65
66 path_max = (unsigned) PATH_MAX;
67 path_max += 2; /* The getcwd docs say to do this. */
68
69 for (;;)
70 {
71 char *cwd = XNMALLOC (path_max, char);
72
73 errno = 0;
74 ret = getcwd (cwd, path_max);
75 if (ret != NULL)
76 return ret;
77 if (errno != ERANGE)
78 {
79 int save_errno = errno;
80 free (cwd);
81 errno = save_errno;
82 return NULL;
83 }
84
85 free (cwd);
86
87 path_max += path_max / 16;
88 path_max += 32;
89 }
90 }
91