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- /* Copyright (C) 1991-2021 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- The GNU C Library 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 3 of the License, or (at your option) any later version.
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
- You should have received a copy of the GNU General Public
- License along with the GNU C Library; if not, see
- <https://www.gnu.org/licenses/>. */
- #if !_LIBC
- # include <config.h>
- # include <unistd.h>
- # include "pathmax.h"
- #else
- # define HAVE_OPENAT 1
- # define D_INO_IN_DIRENT 1
- # define HAVE_MSVC_INVALID_PARAMETER_HANDLER 0
- # define HAVE_MINIMALLY_WORKING_GETCWD 0
- #endif
- #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 or if we're using the
- gnulib replacement function with a native fdopendir, then enable
- code below to make getcwd more efficient and robust. */
- #if defined HAVE_OPENAT || (defined GNULIB_OPENAT && defined HAVE_FDOPENDIR)
- # 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>
- #if _LIBC
- # ifndef mempcpy
- # define mempcpy __mempcpy
- # endif
- #endif
- #ifndef MAX
- # define MAX(a, b) ((a) < (b) ? (b) : (a))
- #endif
- #ifndef MIN
- # define MIN(a, b) ((a) < (b) ? (a) : (b))
- #endif
- /* In this file, PATH_MAX only serves as a threshold for choosing among two
- algorithms. */
- #ifndef PATH_MAX
- # define PATH_MAX 8192
- #endif
- #if D_INO_IN_DIRENT
- # define MATCHING_INO(dp, ino) ((dp)->d_ino == (ino))
- #else
- # define MATCHING_INO(dp, ino) true
- #endif
- #if HAVE_MSVC_INVALID_PARAMETER_HANDLER
- # include "msvc-inval.h"
- #endif
- #if !_LIBC
- # define GETCWD_RETURN_TYPE char *
- # define __close_nocancel_nostatus close
- # define __getcwd_generic rpl_getcwd
- # undef stat64
- # define stat64 stat
- # define __fstat64 fstat
- # define __fstatat64 fstatat
- # define __lstat64 lstat
- # define __closedir closedir
- # define __opendir opendir
- # define __readdir64 readdir
- # define __fdopendir fdopendir
- # define __openat openat
- # define __rewinddir rewinddir
- # define __openat64 openat
- # define dirent64 dirent
- #else
- # include <not-cancel.h>
- #endif
- /* The results of opendir() in this file are not used with dirfd and fchdir,
- and we do not leak fds to any single-threaded code that could use stdio,
- therefore save some unnecessary recursion in fchdir.c.
- FIXME - if the kernel ever adds support for multi-thread safety for
- avoiding standard fds, then we should use opendir_safer and
- openat_safer. */
- #ifdef GNULIB_defined_opendir
- # undef opendir
- #endif
- #ifdef GNULIB_defined_closedir
- # undef closedir
- #endif
- #if defined _WIN32 && !defined __CYGWIN__
- # if HAVE_MSVC_INVALID_PARAMETER_HANDLER
- static char *
- getcwd_nothrow (char *buf, size_t size)
- {
- char *result;
- TRY_MSVC_INVAL
- {
- result = _getcwd (buf, size);
- }
- CATCH_MSVC_INVAL
- {
- result = NULL;
- errno = ERANGE;
- }
- DONE_MSVC_INVAL;
- return result;
- }
- # else
- # define getcwd_nothrow _getcwd
- # endif
- # define getcwd_system getcwd_nothrow
- #else
- # define getcwd_system getcwd
- #endif
- /* Get the name of the current working directory, and put it in SIZE
- bytes of BUF. Returns NULL with errno set 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. */
- GETCWD_RETURN_TYPE
- __getcwd_generic (char *buf, size_t 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 stat64 st;
- size_t allocated = size;
- size_t used;
- #if HAVE_MINIMALLY_WORKING_GETCWD
- /* 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.
- But on AIX 5.1..7.1, the system getcwd is not even minimally
- working: If the current directory name is slightly longer than
- PATH_MAX, it omits the first directory component and returns
- this wrong result with errno = 0. */
- # undef getcwd
- dir = getcwd_system (buf, size);
- if (dir || (size && errno == ERANGE))
- return dir;
- /* Solaris getcwd (NULL, 0) fails with errno == EINVAL, but it has
- internal magic that lets it work even if an ancestor directory is
- inaccessible, which is better in many cases. So in this case try
- again with a buffer that's almost always big enough. */
- if (errno == EINVAL && buf == NULL && size == 0)
- {
- char big_buffer[BIG_FILE_NAME_LENGTH + 1];
- dir = getcwd_system (big_buffer, sizeof big_buffer);
- if (dir)
- return strdup (dir);
- }
- # 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 (errno != ERANGE && errno != ENAMETOOLONG && errno != ENOENT)
- return NULL;
- # endif
- #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 (__lstat64 (".", &st) < 0)
- goto lose;
- thisdev = st.st_dev;
- thisino = st.st_ino;
- if (__lstat64 ("/", &st) < 0)
- goto lose;
- rootdev = st.st_dev;
- rootino = st.st_ino;
- while (!(thisdev == rootdev && thisino == rootino))
- {
- struct dirent64 *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 = __openat64 (fd, "..", O_RDONLY);
- if (fd < 0)
- goto lose;
- fd_needs_closing = true;
- parent_status = __fstat64 (fd, &st);
- #else
- dotlist[dotlen++] = '.';
- dotlist[dotlen++] = '.';
- dotlist[dotlen] = '\0';
- parent_status = __lstat64 (dotlist, &st);
- #endif
- if (parent_status != 0)
- goto lose;
- if (dirstream && __closedir (dirstream) != 0)
- {
- dirstream = NULL;
- goto lose;
- }
- /* Figure out if this directory is a mount point. */
- dotdev = st.st_dev;
- dotino = st.st_ino;
- mount_point = dotdev != thisdev;
- /* Search for the last directory. */
- #if HAVE_OPENAT_SUPPORT
- dirstream = __fdopendir (fd);
- if (dirstream == NULL)
- goto lose;
- 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 = __readdir64 (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 = __readdir64 (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 = __fstatat64 (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 = __lstat64 (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 = (used < allocated ? realloc (dir, used) : dir);
- 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_nocancel_nostatus (fd);
- #else
- if (dotlist != dots)
- free (dotlist);
- #endif
- if (buf == NULL)
- free (dir);
- __set_errno (save);
- }
- return NULL;
- }
- #if defined _LIBC && !defined GETCWD_RETURN_TYPE
- libc_hidden_def (__getcwd)
- weak_alias (__getcwd, getcwd)
- #endif
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