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 3 of the License, or
8 (at your option) any later version.
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
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
25 #include <sys/types.h>
30 #include <fcntl.h> /* For AT_FDCWD on Solaris 9. */
32 /* On a system without the openat function, undefine AT_FDCWD. */
38 # define __set_errno(val) (errno = (val))
42 #ifndef _D_EXACT_NAMLEN
43 # define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
45 #ifndef _D_ALLOC_NAMLEN
46 # define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
55 # define mempcpy __mempcpy
61 /* Work around a bug in Solaris 9 and 10: AT_FDCWD is positive. Its
62 value exceeds INT_MAX, so its use as an int doesn't conform to the
63 C standard, and GCC and Sun C complain in some cases. */
64 #if 0 < AT_FDCWD && AT_FDCWD == 0xffd19553
66 # define AT_FDCWD (-3041965)
70 # define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
72 # define is_ENAMETOOLONG(x) 0
76 # define MAX(a, b) ((a) < (b) ? (b) : (a))
79 # define MIN(a, b) ((a) < (b) ? (a) : (b))
84 # define PATH_MAX MAXPATHLEN
86 # define PATH_MAX 1024
91 # define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
93 # define MATCHING_INO(dp, ino) true
97 # define __getcwd rpl_getcwd
98 # define __lstat lstat
99 # define __closedir closedir
100 # define __opendir opendir
101 # define __readdir readdir
104 /* The results of opendir() in this file are not used with dirfd and fchdir,
105 therefore save some unnecessary recursion in fchdir.c. */
109 /* Get the name of the current working directory, and put it in SIZE
110 bytes of BUF. Returns NULL if the directory couldn't be determined or
111 SIZE was too small. If successful, returns BUF. In GNU, if BUF is
112 NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
113 unless SIZE == 0, in which case it is as big as necessary. */
116 __getcwd (char *buf, size_t size)
118 /* Lengths of big file name components and entire file names, and a
119 deep level of file name nesting. These numbers are not upper
120 bounds; they are merely large values suitable for initial
121 allocations, designed to be large enough for most real-world
125 BIG_FILE_NAME_COMPONENT_LENGTH = 255,
126 BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
132 bool fd_needs_closing = false;
134 char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
135 char *dotlist = dots;
136 size_t dotsize = sizeof dots;
139 DIR *dirstream = NULL;
140 dev_t rootdev, thisdev;
141 ino_t rootino, thisino;
145 size_t allocated = size;
148 #if HAVE_PARTLY_WORKING_GETCWD
149 /* The system getcwd works, except it sometimes fails when it
150 shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
151 AT_FDCWD is not defined, the algorithm below is O(N**2) and this
152 is much slower than the system getcwd (at least on GNU/Linux).
153 So trust the system getcwd's results unless they look
156 Use the system getcwd even if we have openat support, since the
157 system getcwd works even when a parent is unreadable, while the
158 openat-based approach does not. */
161 dir = getcwd (buf, size);
162 if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
170 __set_errno (EINVAL);
174 allocated = BIG_FILE_NAME_LENGTH + 1;
179 dir = malloc (allocated);
186 dirp = dir + allocated;
189 if (__lstat (".", &st) < 0)
194 if (__lstat ("/", &st) < 0)
199 while (!(thisdev == rootdev && thisino == rootino))
208 bool use_d_ino = true;
210 /* Look at the parent directory. */
212 fd = openat (fd, "..", O_RDONLY);
215 fd_needs_closing = true;
216 parent_status = fstat (fd, &st);
218 dotlist[dotlen++] = '.';
219 dotlist[dotlen++] = '.';
220 dotlist[dotlen] = '\0';
221 parent_status = __lstat (dotlist, &st);
223 if (parent_status != 0)
226 if (dirstream && __closedir (dirstream) != 0)
232 /* Figure out if this directory is a mount point. */
235 mount_point = dotdev != thisdev;
237 /* Search for the last directory. */
239 dirstream = fdopendir (fd);
240 if (dirstream == NULL)
242 /* Reset fd. It may have been closed by fdopendir. */
243 fd = dirfd (dirstream);
244 fd_needs_closing = false;
246 dirstream = __opendir (dotlist);
247 if (dirstream == NULL)
249 dotlist[dotlen++] = '/';
253 /* Clear errno to distinguish EOF from error if readdir returns
256 d = __readdir (dirstream);
258 /* When we've iterated through all directory entries without finding
259 one with a matching d_ino, rewind the stream and consider each
260 name again, but this time, using lstat. This is necessary in a
261 chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
262 .., ../.., ../../.., etc. all had the same device number, yet the
263 d_ino values for entries in / did not match those obtained
265 if (d == NULL && errno == 0 && use_d_ino)
268 rewinddir (dirstream);
269 d = __readdir (dirstream);
275 /* EOF on dirstream, which can mean e.g., that the current
276 directory has been removed. */
277 __set_errno (ENOENT);
280 if (d->d_name[0] == '.' &&
281 (d->d_name[1] == '\0' ||
282 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
287 bool match = (MATCHING_INO (d, thisino) || mount_point);
295 entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
297 /* Compute size needed for this file name, or for the file
298 name ".." in the same directory, whichever is larger.
299 Room for ".." might be needed the next time through
301 size_t name_alloc = _D_ALLOC_NAMLEN (d);
302 size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
304 if (filesize < dotlen)
305 goto memory_exhausted;
307 if (dotsize < filesize)
309 /* My, what a deep directory tree you have, Grandma. */
310 size_t newsize = MAX (filesize, dotsize * 2);
312 if (newsize < dotsize)
313 goto memory_exhausted;
316 dotlist = malloc (newsize);
331 memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
332 entry_status = __lstat (dotlist, &st);
334 /* We don't fail here if we cannot stat() a directory entry.
335 This can happen when (network) file systems fail. If this
336 entry is in fact the one we are looking for we will find
337 out soon as we reach the end of the directory without
338 having found anything. */
339 if (entry_status == 0 && S_ISDIR (st.st_mode)
340 && st.st_dev == thisdev && st.st_ino == thisino)
345 dirroom = dirp - dir;
346 namlen = _D_EXACT_NAMLEN (d);
348 if (dirroom <= namlen)
352 __set_errno (ERANGE);
358 size_t oldsize = allocated;
360 allocated += MAX (allocated, namlen);
361 if (allocated < oldsize
362 || ! (tmp = realloc (dir, allocated)))
363 goto memory_exhausted;
365 /* Move current contents up to the end of the buffer.
366 This is guaranteed to be non-overlapping. */
367 dirp = memcpy (tmp + allocated - (oldsize - dirroom),
374 memcpy (dirp, d->d_name, namlen);
381 if (dirstream && __closedir (dirstream) != 0)
387 if (dirp == &dir[allocated - 1])
395 used = dir + allocated - dirp;
396 memmove (dir, dirp, used);
399 /* Ensure that the buffer is only as large as necessary. */
400 buf = realloc (dir, used);
403 /* Either buf was NULL all along, or `realloc' failed but
404 we still have the original string. */
410 __set_errno (ENOMEM);
415 __closedir (dirstream);
417 if (fd_needs_closing)
431 weak_alias (__getcwd, getcwd)