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;
144 #if HAVE_PARTLY_WORKING_GETCWD
145 /* The system getcwd works, except it sometimes fails when it
146 shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
147 AT_FDCWD is not defined, the algorithm below is O(N**2) and this
148 is much slower than the system getcwd (at least on GNU/Linux).
149 So trust the system getcwd's results unless they look
152 Use the system getcwd even if we have openat support, since the
153 system getcwd works even when a parent is unreadable, while the
154 openat-based approach does not. */
157 dir = getcwd (buf, size);
158 if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
166 __set_errno (EINVAL);
170 allocated = BIG_FILE_NAME_LENGTH + 1;
175 dir = malloc (allocated);
182 dirp = dir + allocated;
185 if (__lstat (".", &st) < 0)
190 if (__lstat ("/", &st) < 0)
195 while (!(thisdev == rootdev && thisino == rootino))
204 bool use_d_ino = true;
206 /* Look at the parent directory. */
208 fd = openat (fd, "..", O_RDONLY);
211 fd_needs_closing = true;
212 parent_status = fstat (fd, &st);
214 dotlist[dotlen++] = '.';
215 dotlist[dotlen++] = '.';
216 dotlist[dotlen] = '\0';
217 parent_status = __lstat (dotlist, &st);
219 if (parent_status != 0)
222 if (dirstream && __closedir (dirstream) != 0)
228 /* Figure out if this directory is a mount point. */
231 mount_point = dotdev != thisdev;
233 /* Search for the last directory. */
235 dirstream = fdopendir (fd);
236 if (dirstream == NULL)
238 /* Reset fd. It may have been closed by fdopendir. */
239 fd = dirfd (dirstream);
240 fd_needs_closing = false;
242 dirstream = __opendir (dotlist);
243 if (dirstream == NULL)
245 dotlist[dotlen++] = '/';
249 /* Clear errno to distinguish EOF from error if readdir returns
252 d = __readdir (dirstream);
254 /* When we've iterated through all directory entries without finding
255 one with a matching d_ino, rewind the stream and consider each
256 name again, but this time, using lstat. This is necessary in a
257 chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
258 .., ../.., ../../.., etc. all had the same device number, yet the
259 d_ino values for entries in / did not match those obtained
261 if (d == NULL && errno == 0 && use_d_ino)
264 rewinddir (dirstream);
265 d = __readdir (dirstream);
271 /* EOF on dirstream, which can mean e.g., that the current
272 directory has been removed. */
273 __set_errno (ENOENT);
276 if (d->d_name[0] == '.' &&
277 (d->d_name[1] == '\0' ||
278 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
283 bool match = (MATCHING_INO (d, thisino) || mount_point);
291 entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
293 /* Compute size needed for this file name, or for the file
294 name ".." in the same directory, whichever is larger.
295 Room for ".." might be needed the next time through
297 size_t name_alloc = _D_ALLOC_NAMLEN (d);
298 size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
300 if (filesize < dotlen)
301 goto memory_exhausted;
303 if (dotsize < filesize)
305 /* My, what a deep directory tree you have, Grandma. */
306 size_t newsize = MAX (filesize, dotsize * 2);
308 if (newsize < dotsize)
309 goto memory_exhausted;
312 dotlist = malloc (newsize);
327 memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
328 entry_status = __lstat (dotlist, &st);
330 /* We don't fail here if we cannot stat() a directory entry.
331 This can happen when (network) file systems fail. If this
332 entry is in fact the one we are looking for we will find
333 out soon as we reach the end of the directory without
334 having found anything. */
335 if (entry_status == 0 && S_ISDIR (st.st_mode)
336 && st.st_dev == thisdev && st.st_ino == thisino)
341 dirroom = dirp - dir;
342 namlen = _D_EXACT_NAMLEN (d);
344 if (dirroom <= namlen)
348 __set_errno (ERANGE);
354 size_t oldsize = allocated;
356 allocated += MAX (allocated, namlen);
357 if (allocated < oldsize
358 || ! (tmp = realloc (dir, allocated)))
359 goto memory_exhausted;
361 /* Move current contents up to the end of the buffer.
362 This is guaranteed to be non-overlapping. */
363 dirp = memcpy (tmp + allocated - (oldsize - dirroom),
370 memcpy (dirp, d->d_name, namlen);
377 if (dirstream && __closedir (dirstream) != 0)
383 if (dirp == &dir[allocated - 1])
391 used = dir + allocated - dirp;
392 memmove (dir, dirp, used);
394 if (buf == NULL && size == 0)
395 /* Ensure that the buffer is only as large as necessary. */
396 buf = realloc (dir, used);
399 /* Either buf was NULL all along, or `realloc' failed but
400 we still have the original string. */
406 __set_errno (ENOMEM);
411 __closedir (dirstream);
413 if (fd_needs_closing)
427 weak_alias (__getcwd, getcwd)