1 /* Copyright (C) 1991,92,93,94,95,96,97,98,99,2004,2005,2006,2007 Free Software
3 This file is part of the GNU C Library.
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 2, or (at your option)
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.
15 You should have received a copy of the GNU General Public License along
16 with this program; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
26 #include <sys/types.h>
31 #include <fcntl.h> /* For AT_FDCWD on Solaris 9. */
34 # define __set_errno(val) (errno = (val))
38 #ifndef _D_EXACT_NAMLEN
39 # define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
41 #ifndef _D_ALLOC_NAMLEN
42 # define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
51 # define mempcpy __mempcpy
57 /* Work around a bug in Solaris 9 and 10: AT_FDCWD is positive. Its
58 value exceeds INT_MAX, so its use as an int doesn't conform to the
59 C standard, and GCC and Sun C complain in some cases. */
60 #if 0 < AT_FDCWD && AT_FDCWD == 0xffd19553
62 # define AT_FDCWD (-3041965)
66 # define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
68 # define is_ENAMETOOLONG(x) 0
72 # define MAX(a, b) ((a) < (b) ? (b) : (a))
75 # define MIN(a, b) ((a) < (b) ? (a) : (b))
80 # define PATH_MAX MAXPATHLEN
82 # define PATH_MAX 1024
87 # define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
89 # define MATCHING_INO(dp, ino) true
93 # define __getcwd getcwd
94 # define __lstat lstat
95 # define __closedir closedir
96 # define __opendir opendir
97 # define __readdir readdir
100 /* The results of opendir() in this file are not used with dirfd and fchdir,
101 therefore save some unnecessary recursion in fchdir.c. */
105 /* Get the name of the current working directory, and put it in SIZE
106 bytes of BUF. Returns NULL if the directory couldn't be determined or
107 SIZE was too small. If successful, returns BUF. In GNU, if BUF is
108 NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
109 unless SIZE == 0, in which case it is as big as necessary. */
112 __getcwd (char *buf, size_t size)
114 /* Lengths of big file name components and entire file names, and a
115 deep level of file name nesting. These numbers are not upper
116 bounds; they are merely large values suitable for initial
117 allocations, designed to be large enough for most real-world
121 BIG_FILE_NAME_COMPONENT_LENGTH = 255,
122 BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
128 bool fd_needs_closing = false;
130 char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
131 char *dotlist = dots;
132 size_t dotsize = sizeof dots;
135 DIR *dirstream = NULL;
136 dev_t rootdev, thisdev;
137 ino_t rootino, thisino;
141 size_t allocated = size;
148 __set_errno (EINVAL);
152 allocated = BIG_FILE_NAME_LENGTH + 1;
157 dir = malloc (allocated);
164 #if HAVE_PARTLY_WORKING_GETCWD
165 /* The system getcwd works, except it sometimes fails when it
166 shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
167 AT_FDCWD is not defined, the algorithm below is O(N**2) and this
168 is much slower than the system getcwd (at least on GNU/Linux).
169 So trust the system getcwd's results unless they look
172 Use the system getcwd even if we have openat support, since the
173 system getcwd works even when a parent is unreadable, while the
174 openat-based approach does not. */
177 if (getcwd (dir, allocated))
179 if (buf == NULL && size == 0)
180 buf = realloc (dir, strlen (dir) + 1);
181 return (buf ? buf : dir);
184 if (! (errno == ERANGE || is_ENAMETOOLONG (errno) || errno == ENOENT))
188 dirp = dir + allocated;
191 if (__lstat (".", &st) < 0)
196 if (__lstat ("/", &st) < 0)
201 while (!(thisdev == rootdev && thisino == rootino))
210 bool use_d_ino = true;
212 /* Look at the parent directory. */
214 fd = openat (fd, "..", O_RDONLY);
217 fd_needs_closing = true;
218 parent_status = fstat (fd, &st);
220 dotlist[dotlen++] = '.';
221 dotlist[dotlen++] = '.';
222 dotlist[dotlen] = '\0';
223 parent_status = __lstat (dotlist, &st);
225 if (parent_status != 0)
228 if (dirstream && __closedir (dirstream) != 0)
234 /* Figure out if this directory is a mount point. */
237 mount_point = dotdev != thisdev;
239 /* Search for the last directory. */
241 dirstream = fdopendir (fd);
242 if (dirstream == NULL)
244 /* Reset fd. It may have been closed by fdopendir. */
245 fd = dirfd (dirstream);
246 fd_needs_closing = false;
248 dirstream = __opendir (dotlist);
249 if (dirstream == NULL)
251 dotlist[dotlen++] = '/';
255 /* Clear errno to distinguish EOF from error if readdir returns
258 d = __readdir (dirstream);
260 /* When we've iterated through all directory entries without finding
261 one with a matching d_ino, rewind the stream and consider each
262 name again, but this time, using lstat. This is necessary in a
263 chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
264 .., ../.., ../../.., etc. all had the same device number, yet the
265 d_ino values for entries in / did not match those obtained
267 if (d == NULL && errno == 0 && use_d_ino)
270 rewinddir (dirstream);
271 d = __readdir (dirstream);
277 /* EOF on dirstream, which can mean e.g., that the current
278 directory has been removed. */
279 __set_errno (ENOENT);
282 if (d->d_name[0] == '.' &&
283 (d->d_name[1] == '\0' ||
284 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
289 bool match = (MATCHING_INO (d, thisino) || mount_point);
297 entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
299 /* Compute size needed for this file name, or for the file
300 name ".." in the same directory, whichever is larger.
301 Room for ".." might be needed the next time through
303 size_t name_alloc = _D_ALLOC_NAMLEN (d);
304 size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
306 if (filesize < dotlen)
307 goto memory_exhausted;
309 if (dotsize < filesize)
311 /* My, what a deep directory tree you have, Grandma. */
312 size_t newsize = MAX (filesize, dotsize * 2);
314 if (newsize < dotsize)
315 goto memory_exhausted;
318 dotlist = malloc (newsize);
333 memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
334 entry_status = __lstat (dotlist, &st);
336 /* We don't fail here if we cannot stat() a directory entry.
337 This can happen when (network) file systems fail. If this
338 entry is in fact the one we are looking for we will find
339 out soon as we reach the end of the directory without
340 having found anything. */
341 if (entry_status == 0 && S_ISDIR (st.st_mode)
342 && st.st_dev == thisdev && st.st_ino == thisino)
347 dirroom = dirp - dir;
348 namlen = _D_EXACT_NAMLEN (d);
350 if (dirroom <= namlen)
354 __set_errno (ERANGE);
360 size_t oldsize = allocated;
362 allocated += MAX (allocated, namlen);
363 if (allocated < oldsize
364 || ! (tmp = realloc (dir, allocated)))
365 goto memory_exhausted;
367 /* Move current contents up to the end of the buffer.
368 This is guaranteed to be non-overlapping. */
369 dirp = memcpy (tmp + allocated - (oldsize - dirroom),
376 memcpy (dirp, d->d_name, namlen);
383 if (dirstream && __closedir (dirstream) != 0)
389 if (dirp == &dir[allocated - 1])
397 used = dir + allocated - dirp;
398 memmove (dir, dirp, used);
400 if (buf == NULL && size == 0)
401 /* Ensure that the buffer is only as large as necessary. */
402 buf = realloc (dir, used);
405 /* Either buf was NULL all along, or `realloc' failed but
406 we still have the original string. */
412 __set_errno (ENOMEM);
417 __closedir (dirstream);
419 if (fd_needs_closing)
433 weak_alias (__getcwd, getcwd)