1 /* Copyright (C) 1991,92,93,94,95,96,97,98,99,2004,2005,2006 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. */
28 #include <sys/types.h>
33 #include <fcntl.h> /* For AT_FDCWD on Solaris 9. */
36 # define __set_errno(val) (errno = (val))
40 #ifndef _D_EXACT_NAMLEN
41 # define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
43 #ifndef _D_ALLOC_NAMLEN
44 # define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
53 # 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 getcwd
98 # define __lstat lstat
99 # define __closedir closedir
100 # define __opendir opendir
101 # define __readdir readdir
104 /* Get the name of the current working directory, and put it in SIZE
105 bytes of BUF. Returns NULL if the directory couldn't be determined or
106 SIZE was too small. If successful, returns BUF. In GNU, if BUF is
107 NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
108 unless SIZE == 0, in which case it is as big as necessary. */
111 __getcwd (char *buf, size_t size)
113 /* Lengths of big file name components and entire file names, and a
114 deep level of file name nesting. These numbers are not upper
115 bounds; they are merely large values suitable for initial
116 allocations, designed to be large enough for most real-world
120 BIG_FILE_NAME_COMPONENT_LENGTH = 255,
121 BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
127 bool fd_needs_closing = false;
129 char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
130 char *dotlist = dots;
131 size_t dotsize = sizeof dots;
134 DIR *dirstream = NULL;
135 dev_t rootdev, thisdev;
136 ino_t rootino, thisino;
140 size_t allocated = size;
143 #if HAVE_PARTLY_WORKING_GETCWD && !defined AT_FDCWD
144 /* The system getcwd works, except it sometimes fails when it
145 shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
146 AT_FDCWD is not defined, the algorithm below is O(N**2) and this
147 is much slower than the system getcwd (at least on GNU/Linux).
148 So trust the system getcwd's results unless they look
151 dir = getcwd (buf, size);
152 if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
160 __set_errno (EINVAL);
164 allocated = BIG_FILE_NAME_LENGTH + 1;
169 dir = malloc (allocated);
176 dirp = dir + allocated;
179 if (__lstat (".", &st) < 0)
184 if (__lstat ("/", &st) < 0)
189 while (!(thisdev == rootdev && thisino == rootino))
198 bool use_d_ino = true;
200 /* Look at the parent directory. */
202 fd = openat (fd, "..", O_RDONLY);
205 fd_needs_closing = true;
206 parent_status = fstat (fd, &st);
208 dotlist[dotlen++] = '.';
209 dotlist[dotlen++] = '.';
210 dotlist[dotlen] = '\0';
211 parent_status = __lstat (dotlist, &st);
213 if (parent_status != 0)
216 if (dirstream && __closedir (dirstream) != 0)
222 /* Figure out if this directory is a mount point. */
225 mount_point = dotdev != thisdev;
227 /* Search for the last directory. */
229 dirstream = fdopendir (fd);
230 if (dirstream == NULL)
232 fd_needs_closing = false;
234 dirstream = __opendir (dotlist);
235 if (dirstream == NULL)
237 dotlist[dotlen++] = '/';
241 /* Clear errno to distinguish EOF from error if readdir returns
244 d = __readdir (dirstream);
246 /* When we've iterated through all directory entries without finding
247 one with a matching d_ino, rewind the stream and consider each
248 name again, but this time, using lstat. This is necessary in a
249 chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
250 .., ../.., ../../.., etc. all had the same device number, yet the
251 d_ino values for entries in / did not match those obtained
253 if (d == NULL && errno == 0 && use_d_ino)
256 rewinddir (dirstream);
257 d = __readdir (dirstream);
263 /* EOF on dirstream, which can mean e.g., that the current
264 directory has been removed. */
265 __set_errno (ENOENT);
268 if (d->d_name[0] == '.' &&
269 (d->d_name[1] == '\0' ||
270 (d->d_name[1] == '.' && d->d_name[2] == '\0')))
275 bool match = (MATCHING_INO (d, thisino) || mount_point);
283 entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
285 /* Compute size needed for this file name, or for the file
286 name ".." in the same directory, whichever is larger.
287 Room for ".." might be needed the next time through
289 size_t name_alloc = _D_ALLOC_NAMLEN (d);
290 size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
292 if (filesize < dotlen)
293 goto memory_exhausted;
295 if (dotsize < filesize)
297 /* My, what a deep directory tree you have, Grandma. */
298 size_t newsize = MAX (filesize, dotsize * 2);
300 if (newsize < dotsize)
301 goto memory_exhausted;
304 dotlist = malloc (newsize);
319 memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
320 entry_status = __lstat (dotlist, &st);
322 /* We don't fail here if we cannot stat() a directory entry.
323 This can happen when (network) file systems fail. If this
324 entry is in fact the one we are looking for we will find
325 out soon as we reach the end of the directory without
326 having found anything. */
327 if (entry_status == 0 && S_ISDIR (st.st_mode)
328 && st.st_dev == thisdev && st.st_ino == thisino)
333 dirroom = dirp - dir;
334 namlen = _D_EXACT_NAMLEN (d);
336 if (dirroom <= namlen)
340 __set_errno (ERANGE);
346 size_t oldsize = allocated;
348 allocated += MAX (allocated, namlen);
349 if (allocated < oldsize
350 || ! (tmp = realloc (dir, allocated)))
351 goto memory_exhausted;
353 /* Move current contents up to the end of the buffer.
354 This is guaranteed to be non-overlapping. */
355 dirp = memcpy (tmp + allocated - (oldsize - dirroom),
362 memcpy (dirp, d->d_name, namlen);
369 if (dirstream && __closedir (dirstream) != 0)
375 if (dirp == &dir[allocated - 1])
383 used = dir + allocated - dirp;
384 memmove (dir, dirp, used);
386 if (buf == NULL && size == 0)
387 /* Ensure that the buffer is only as large as necessary. */
388 buf = realloc (dir, used);
391 /* Either buf was NULL all along, or `realloc' failed but
392 we still have the original string. */
398 __set_errno (ENOMEM);
403 __closedir (dirstream);
405 if (fd_needs_closing)
419 weak_alias (__getcwd, getcwd)