1 /* Copyright (C) 1991-1999, 2004-2009 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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 3 of the License, or
7 (at your option) any later version.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include <sys/types.h>
28 #include <fcntl.h> /* For AT_FDCWD on Solaris 9. */
30 /* If this host provides the openat function, then enable
31 code below to make getcwd more efficient and robust. */
33 # define HAVE_OPENAT_SUPPORT 1
35 # define HAVE_OPENAT_SUPPORT 0
39 # define __set_errno(val) (errno = (val))
43 #ifndef _D_EXACT_NAMLEN
44 # define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
46 #ifndef _D_ALLOC_NAMLEN
47 # define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
56 # define mempcpy __mempcpy
62 /* Work around a bug in Solaris 9 and 10: AT_FDCWD is positive. Its
63 value exceeds INT_MAX, so its use as an int doesn't conform to the
64 C standard, and GCC and Sun C complain in some cases. */
65 #if 0 < AT_FDCWD && AT_FDCWD == 0xffd19553
67 # define AT_FDCWD (-3041965)
71 # define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
73 # define is_ENAMETOOLONG(x) 0
77 # define MAX(a, b) ((a) < (b) ? (b) : (a))
80 # define MIN(a, b) ((a) < (b) ? (a) : (b))
85 # define PATH_MAX MAXPATHLEN
87 # define PATH_MAX 1024
92 # define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
94 # define MATCHING_INO(dp, ino) true
98 # define __getcwd rpl_getcwd
99 # define __lstat lstat
100 # define __closedir closedir
101 # define __opendir opendir
102 # define __readdir readdir
105 /* The results of opendir() in this file are not used with dirfd and fchdir,
106 and we do not leak fds to any single-threaded code that could use stdio,
107 therefore save some unnecessary recursion in fchdir.c.
108 FIXME - if the kernel ever adds support for multi-thread safety for
109 avoiding standard fds, then we should use opendir_safer and
114 /* Get the name of the current working directory, and put it in SIZE
115 bytes of BUF. Returns NULL if the directory couldn't be determined or
116 SIZE was too small. If successful, returns BUF. In GNU, if BUF is
117 NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
118 unless SIZE == 0, in which case it is as big as necessary. */
121 __getcwd (char *buf, size_t size)
123 /* Lengths of big file name components and entire file names, and a
124 deep level of file name nesting. These numbers are not upper
125 bounds; they are merely large values suitable for initial
126 allocations, designed to be large enough for most real-world
130 BIG_FILE_NAME_COMPONENT_LENGTH = 255,
131 BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
135 #if HAVE_OPENAT_SUPPORT
137 bool fd_needs_closing = false;
139 char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
140 char *dotlist = dots;
141 size_t dotsize = sizeof dots;
144 DIR *dirstream = NULL;
145 dev_t rootdev, thisdev;
146 ino_t rootino, thisino;
150 size_t allocated = size;
153 #if HAVE_PARTLY_WORKING_GETCWD
154 /* The system getcwd works, except it sometimes fails when it
155 shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
156 AT_FDCWD is not defined, the algorithm below is O(N**2) and this
157 is much slower than the system getcwd (at least on GNU/Linux).
158 So trust the system getcwd's results unless they look
161 Use the system getcwd even if we have openat support, since the
162 system getcwd works even when a parent is unreadable, while the
163 openat-based approach does not. */
166 dir = getcwd (buf, size);
167 if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
175 __set_errno (EINVAL);
179 allocated = BIG_FILE_NAME_LENGTH + 1;
184 dir = malloc (allocated);
191 dirp = dir + allocated;
194 if (__lstat (".", &st) < 0)
199 if (__lstat ("/", &st) < 0)
204 while (!(thisdev == rootdev && thisino == rootino))
213 bool use_d_ino = true;
215 /* Look at the parent directory. */
216 #if HAVE_OPENAT_SUPPORT
217 fd = openat (fd, "..", O_RDONLY);
220 fd_needs_closing = true;
221 parent_status = fstat (fd, &st);
223 dotlist[dotlen++] = '.';
224 dotlist[dotlen++] = '.';
225 dotlist[dotlen] = '\0';
226 parent_status = __lstat (dotlist, &st);
228 if (parent_status != 0)
231 if (dirstream && __closedir (dirstream) != 0)
237 /* Figure out if this directory is a mount point. */
240 mount_point = dotdev != thisdev;
242 /* Search for the last directory. */
243 #if HAVE_OPENAT_SUPPORT
244 dirstream = fdopendir (fd);
245 if (dirstream == NULL)
247 /* Reset fd. It may have been closed by fdopendir. */
248 fd = dirfd (dirstream);
249 fd_needs_closing = false;
251 dirstream = __opendir (dotlist);
252 if (dirstream == NULL)
254 dotlist[dotlen++] = '/';
258 /* Clear errno to distinguish EOF from error if readdir returns
261 d = __readdir (dirstream);
263 /* When we've iterated through all directory entries without finding
264 one with a matching d_ino, rewind the stream and consider each
265 name again, but this time, using lstat. This is necessary in a
266 chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
267 .., ../.., ../../.., etc. all had the same device number, yet the
268 d_ino values for entries in / did not match those obtained
270 if (d == NULL && errno == 0 && use_d_ino)
273 rewinddir (dirstream);
274 d = __readdir (dirstream);
280 /* EOF on dirstream, which can mean e.g., that the current
281 directory has been removed. */
282 __set_errno (ENOENT);
285 if (d->d_name[0] == '.' &&
286 (d->d_name[1] == '\0' ||
287 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
292 bool match = (MATCHING_INO (d, thisino) || mount_point);
299 #if HAVE_OPENAT_SUPPORT
300 entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
302 /* Compute size needed for this file name, or for the file
303 name ".." in the same directory, whichever is larger.
304 Room for ".." might be needed the next time through
306 size_t name_alloc = _D_ALLOC_NAMLEN (d);
307 size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
309 if (filesize < dotlen)
310 goto memory_exhausted;
312 if (dotsize < filesize)
314 /* My, what a deep directory tree you have, Grandma. */
315 size_t newsize = MAX (filesize, dotsize * 2);
317 if (newsize < dotsize)
318 goto memory_exhausted;
321 dotlist = malloc (newsize);
336 memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
337 entry_status = __lstat (dotlist, &st);
339 /* We don't fail here if we cannot stat() a directory entry.
340 This can happen when (network) file systems fail. If this
341 entry is in fact the one we are looking for we will find
342 out soon as we reach the end of the directory without
343 having found anything. */
344 if (entry_status == 0 && S_ISDIR (st.st_mode)
345 && st.st_dev == thisdev && st.st_ino == thisino)
350 dirroom = dirp - dir;
351 namlen = _D_EXACT_NAMLEN (d);
353 if (dirroom <= namlen)
357 __set_errno (ERANGE);
363 size_t oldsize = allocated;
365 allocated += MAX (allocated, namlen);
366 if (allocated < oldsize
367 || ! (tmp = realloc (dir, allocated)))
368 goto memory_exhausted;
370 /* Move current contents up to the end of the buffer.
371 This is guaranteed to be non-overlapping. */
372 dirp = memcpy (tmp + allocated - (oldsize - dirroom),
379 memcpy (dirp, d->d_name, namlen);
386 if (dirstream && __closedir (dirstream) != 0)
392 if (dirp == &dir[allocated - 1])
395 #if ! HAVE_OPENAT_SUPPORT
400 used = dir + allocated - dirp;
401 memmove (dir, dirp, used);
404 /* Ensure that the buffer is only as large as necessary. */
405 buf = realloc (dir, used);
408 /* Either buf was NULL all along, or `realloc' failed but
409 we still have the original string. */
415 __set_errno (ENOMEM);
420 __closedir (dirstream);
421 #if HAVE_OPENAT_SUPPORT
422 if (fd_needs_closing)
436 weak_alias (__getcwd, getcwd)