-/* Provide a replacement for the POSIX getcwd function.
- Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+/* Copyright (C) 1991,92,93,94,95,96,97,98,99,2004,2005,2006,2007 Free Software
+ Foundation, Inc.
+ This file is part of the GNU C Library.
- This program is free software; you can redistribute it and/or modify
+ This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software Foundation,
- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
-/* written by Jim Meyering */
+#if !_LIBC
+# include <config.h>
+# include <unistd.h>
+# include "dirfd.h"
+#endif
-#include <config.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+#include <fcntl.h> /* For AT_FDCWD on Solaris 9. */
+
+/* If this host provides the openat function, then enable
+ code below to make getcwd more efficient and robust. */
+#ifdef HAVE_OPENAT
+# define HAVE_OPENAT_SUPPORT 1
+#else
+# define HAVE_OPENAT_SUPPORT 0
+#endif
+
+#ifndef __set_errno
+# define __set_errno(val) (errno = (val))
+#endif
+
+#include <dirent.h>
+#ifndef _D_EXACT_NAMLEN
+# define _D_EXACT_NAMLEN(d) strlen ((d)->d_name)
+#endif
+#ifndef _D_ALLOC_NAMLEN
+# define _D_ALLOC_NAMLEN(d) (_D_EXACT_NAMLEN (d) + 1)
+#endif
+#include <unistd.h>
#include <stdlib.h>
#include <string.h>
-#include <errno.h>
-#include <sys/types.h>
-#include "pathmax.h"
-#include "same.h"
+#if _LIBC
+# ifndef mempcpy
+# define mempcpy __mempcpy
+# endif
+#endif
+
+#include <limits.h>
-/* Guess high, because that makes the test below more conservative.
- But this is a kludge, because we should really use
- pathconf (".", _PC_NAME_MAX). But it's probably not worth the cost. */
-#define KLUDGE_POSIX_NAME_MAX 255
+/* Work around a bug in Solaris 9 and 10: AT_FDCWD is positive. Its
+ value exceeds INT_MAX, so its use as an int doesn't conform to the
+ C standard, and GCC and Sun C complain in some cases. */
+#if 0 < AT_FDCWD && AT_FDCWD == 0xffd19553
+# undef AT_FDCWD
+# define AT_FDCWD (-3041965)
+#endif
-#define MAX_SAFE_LEN (PATH_MAX - 1 - KLUDGE_POSIX_NAME_MAX - 1)
+#ifdef ENAMETOOLONG
+# define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG)
+#else
+# define is_ENAMETOOLONG(x) 0
+#endif
-/* Undefine getcwd here, as near the use as possible, in case any
- of the files included above define it to rpl_getcwd. */
-#undef getcwd
+#ifndef MAX
+# define MAX(a, b) ((a) < (b) ? (b) : (a))
+#endif
+#ifndef MIN
+# define MIN(a, b) ((a) < (b) ? (a) : (b))
+#endif
-/* Any declaration of getcwd from headers included above has
- been changed to a declaration of rpl_getcwd. Declare it here. */
-extern char *getcwd (char *buf, size_t size);
+#ifndef PATH_MAX
+# ifdef MAXPATHLEN
+# define PATH_MAX MAXPATHLEN
+# else
+# define PATH_MAX 1024
+# endif
+#endif
-/* This is a wrapper for getcwd.
- Some implementations (at least GNU libc 2.3.1 + linux-2.4.20) return
- non-NULL for a working directory name longer than PATH_MAX, yet the
- returned string is a strict prefix of the desired directory name.
- Upon such a failure, free the offending string, set errno to
- ENAMETOOLONG, and return NULL.
+#if D_INO_IN_DIRENT
+# define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
+#else
+# define MATCHING_INO(dp, ino) true
+#endif
- I've heard that this is a Linux kernel bug, and that it has
- been fixed between 2.4.21-pre3 and 2.4.21-pre4. */
+#if !_LIBC
+# define __getcwd rpl_getcwd
+# define __lstat lstat
+# define __closedir closedir
+# define __opendir opendir
+# define __readdir readdir
+#endif
+
+/* The results of opendir() in this file are not used with dirfd and fchdir,
+ therefore save some unnecessary recursion in fchdir.c. */
+#undef opendir
+#undef closedir
+\f
+/* Get the name of the current working directory, and put it in SIZE
+ bytes of BUF. Returns NULL if the directory couldn't be determined or
+ SIZE was too small. If successful, returns BUF. In GNU, if BUF is
+ NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
+ unless SIZE == 0, in which case it is as big as necessary. */
char *
-rpl_getcwd (char *buf, size_t size)
+__getcwd (char *buf, size_t size)
{
- char *cwd = getcwd (buf, size);
+ /* Lengths of big file name components and entire file names, and a
+ deep level of file name nesting. These numbers are not upper
+ bounds; they are merely large values suitable for initial
+ allocations, designed to be large enough for most real-world
+ uses. */
+ enum
+ {
+ BIG_FILE_NAME_COMPONENT_LENGTH = 255,
+ BIG_FILE_NAME_LENGTH = MIN (4095, PATH_MAX - 1),
+ DEEP_NESTING = 100
+ };
+
+#if HAVE_OPENAT_SUPPORT
+ int fd = AT_FDCWD;
+ bool fd_needs_closing = false;
+#else
+ char dots[DEEP_NESTING * sizeof ".." + BIG_FILE_NAME_COMPONENT_LENGTH + 1];
+ char *dotlist = dots;
+ size_t dotsize = sizeof dots;
+ size_t dotlen = 0;
+#endif
+ DIR *dirstream = NULL;
+ dev_t rootdev, thisdev;
+ ino_t rootino, thisino;
+ char *dir;
+ register char *dirp;
+ struct stat st;
+ size_t allocated = size;
+ size_t used;
+
+#if HAVE_PARTLY_WORKING_GETCWD
+ /* The system getcwd works, except it sometimes fails when it
+ shouldn't, setting errno to ERANGE, ENAMETOOLONG, or ENOENT. If
+ AT_FDCWD is not defined, the algorithm below is O(N**2) and this
+ is much slower than the system getcwd (at least on GNU/Linux).
+ So trust the system getcwd's results unless they look
+ suspicious.
+
+ Use the system getcwd even if we have openat support, since the
+ system getcwd works even when a parent is unreadable, while the
+ openat-based approach does not. */
+
+# undef getcwd
+ dir = getcwd (buf, size);
+ if (dir || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
+ return dir;
+#endif
+
+ if (size == 0)
+ {
+ if (buf != NULL)
+ {
+ __set_errno (EINVAL);
+ return NULL;
+ }
+
+ allocated = BIG_FILE_NAME_LENGTH + 1;
+ }
+
+ if (buf == NULL)
+ {
+ dir = malloc (allocated);
+ if (dir == NULL)
+ return NULL;
+ }
+ else
+ dir = buf;
+
+ dirp = dir + allocated;
+ *--dirp = '\0';
+
+ if (__lstat (".", &st) < 0)
+ goto lose;
+ thisdev = st.st_dev;
+ thisino = st.st_ino;
+
+ if (__lstat ("/", &st) < 0)
+ goto lose;
+ rootdev = st.st_dev;
+ rootino = st.st_ino;
+
+ while (!(thisdev == rootdev && thisino == rootino))
+ {
+ struct dirent *d;
+ dev_t dotdev;
+ ino_t dotino;
+ bool mount_point;
+ int parent_status;
+ size_t dirroom;
+ size_t namlen;
+ bool use_d_ino = true;
+
+ /* Look at the parent directory. */
+#if HAVE_OPENAT_SUPPORT
+ fd = openat (fd, "..", O_RDONLY);
+ if (fd < 0)
+ goto lose;
+ fd_needs_closing = true;
+ parent_status = fstat (fd, &st);
+#else
+ dotlist[dotlen++] = '.';
+ dotlist[dotlen++] = '.';
+ dotlist[dotlen] = '\0';
+ parent_status = __lstat (dotlist, &st);
+#endif
+ if (parent_status != 0)
+ goto lose;
- if (cwd == NULL)
- return NULL;
+ if (dirstream && __closedir (dirstream) != 0)
+ {
+ dirstream = NULL;
+ goto lose;
+ }
- if (strlen (cwd) <= MAX_SAFE_LEN || same_name (cwd, "."))
- return cwd;
+ /* Figure out if this directory is a mount point. */
+ dotdev = st.st_dev;
+ dotino = st.st_ino;
+ mount_point = dotdev != thisdev;
- free (cwd);
- errno = ENAMETOOLONG;
+ /* Search for the last directory. */
+#if HAVE_OPENAT_SUPPORT
+ dirstream = fdopendir (fd);
+ if (dirstream == NULL)
+ goto lose;
+ /* Reset fd. It may have been closed by fdopendir. */
+ fd = dirfd (dirstream);
+ fd_needs_closing = false;
+#else
+ dirstream = __opendir (dotlist);
+ if (dirstream == NULL)
+ goto lose;
+ dotlist[dotlen++] = '/';
+#endif
+ for (;;)
+ {
+ /* Clear errno to distinguish EOF from error if readdir returns
+ NULL. */
+ __set_errno (0);
+ d = __readdir (dirstream);
+
+ /* When we've iterated through all directory entries without finding
+ one with a matching d_ino, rewind the stream and consider each
+ name again, but this time, using lstat. This is necessary in a
+ chroot on at least one system (glibc-2.3.6 + linux 2.6.12), where
+ .., ../.., ../../.., etc. all had the same device number, yet the
+ d_ino values for entries in / did not match those obtained
+ via lstat. */
+ if (d == NULL && errno == 0 && use_d_ino)
+ {
+ use_d_ino = false;
+ rewinddir (dirstream);
+ d = __readdir (dirstream);
+ }
+
+ if (d == NULL)
+ {
+ if (errno == 0)
+ /* EOF on dirstream, which can mean e.g., that the current
+ directory has been removed. */
+ __set_errno (ENOENT);
+ goto lose;
+ }
+ if (d->d_name[0] == '.' &&
+ (d->d_name[1] == '\0' ||
+ (d->d_name[1] == '.' && d->d_name[2] == '\0')))
+ continue;
+
+ if (use_d_ino)
+ {
+ bool match = (MATCHING_INO (d, thisino) || mount_point);
+ if (! match)
+ continue;
+ }
+
+ {
+ int entry_status;
+#if HAVE_OPENAT_SUPPORT
+ entry_status = fstatat (fd, d->d_name, &st, AT_SYMLINK_NOFOLLOW);
+#else
+ /* Compute size needed for this file name, or for the file
+ name ".." in the same directory, whichever is larger.
+ Room for ".." might be needed the next time through
+ the outer loop. */
+ size_t name_alloc = _D_ALLOC_NAMLEN (d);
+ size_t filesize = dotlen + MAX (sizeof "..", name_alloc);
+
+ if (filesize < dotlen)
+ goto memory_exhausted;
+
+ if (dotsize < filesize)
+ {
+ /* My, what a deep directory tree you have, Grandma. */
+ size_t newsize = MAX (filesize, dotsize * 2);
+ size_t i;
+ if (newsize < dotsize)
+ goto memory_exhausted;
+ if (dotlist != dots)
+ free (dotlist);
+ dotlist = malloc (newsize);
+ if (dotlist == NULL)
+ goto lose;
+ dotsize = newsize;
+
+ i = 0;
+ do
+ {
+ dotlist[i++] = '.';
+ dotlist[i++] = '.';
+ dotlist[i++] = '/';
+ }
+ while (i < dotlen);
+ }
+
+ memcpy (dotlist + dotlen, d->d_name, _D_ALLOC_NAMLEN (d));
+ entry_status = __lstat (dotlist, &st);
+#endif
+ /* We don't fail here if we cannot stat() a directory entry.
+ This can happen when (network) file systems fail. If this
+ entry is in fact the one we are looking for we will find
+ out soon as we reach the end of the directory without
+ having found anything. */
+ if (entry_status == 0 && S_ISDIR (st.st_mode)
+ && st.st_dev == thisdev && st.st_ino == thisino)
+ break;
+ }
+ }
+
+ dirroom = dirp - dir;
+ namlen = _D_EXACT_NAMLEN (d);
+
+ if (dirroom <= namlen)
+ {
+ if (size != 0)
+ {
+ __set_errno (ERANGE);
+ goto lose;
+ }
+ else
+ {
+ char *tmp;
+ size_t oldsize = allocated;
+
+ allocated += MAX (allocated, namlen);
+ if (allocated < oldsize
+ || ! (tmp = realloc (dir, allocated)))
+ goto memory_exhausted;
+
+ /* Move current contents up to the end of the buffer.
+ This is guaranteed to be non-overlapping. */
+ dirp = memcpy (tmp + allocated - (oldsize - dirroom),
+ tmp + dirroom,
+ oldsize - dirroom);
+ dir = tmp;
+ }
+ }
+ dirp -= namlen;
+ memcpy (dirp, d->d_name, namlen);
+ *--dirp = '/';
+
+ thisdev = dotdev;
+ thisino = dotino;
+ }
+
+ if (dirstream && __closedir (dirstream) != 0)
+ {
+ dirstream = NULL;
+ goto lose;
+ }
+
+ if (dirp == &dir[allocated - 1])
+ *--dirp = '/';
+
+#if ! HAVE_OPENAT_SUPPORT
+ if (dotlist != dots)
+ free (dotlist);
+#endif
+
+ used = dir + allocated - dirp;
+ memmove (dir, dirp, used);
+
+ if (size == 0)
+ /* Ensure that the buffer is only as large as necessary. */
+ buf = realloc (dir, used);
+
+ if (buf == NULL)
+ /* Either buf was NULL all along, or `realloc' failed but
+ we still have the original string. */
+ buf = dir;
+
+ return buf;
+
+ memory_exhausted:
+ __set_errno (ENOMEM);
+ lose:
+ {
+ int save = errno;
+ if (dirstream)
+ __closedir (dirstream);
+#if HAVE_OPENAT_SUPPORT
+ if (fd_needs_closing)
+ close (fd);
+#else
+ if (dotlist != dots)
+ free (dotlist);
+#endif
+ if (buf == NULL)
+ free (dir);
+ __set_errno (save);
+ }
return NULL;
}
+
+#ifdef weak_alias
+weak_alias (__getcwd, getcwd)
+#endif
projects / gnulib.git / blobdiff