mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-29 14:01:20 +00:00
503 lines
14 KiB
C
503 lines
14 KiB
C
/* Copyright (C) 1991-2024 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 Lesser General Public
|
||
License as published by the Free Software Foundation; either
|
||
version 2.1 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
|
||
Lesser General Public License for more details.
|
||
|
||
You should have received a copy of the GNU Lesser 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 __close_nocancel_nostatus close
|
||
# define __getcwd_generic rpl_getcwd
|
||
# 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_t64 st;
|
||
size_t allocated = size;
|
||
size_t used;
|
||
|
||
/* A size of 1 byte is never useful. */
|
||
if (allocated == 1)
|
||
{
|
||
__set_errno (ERANGE);
|
||
return NULL;
|
||
}
|
||
|
||
#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_time64 (".", &st) < 0)
|
||
goto lose;
|
||
thisdev = st.st_dev;
|
||
thisino = st.st_ino;
|
||
|
||
if (__lstat64_time64 ("/", &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_time64 (fd, &st);
|
||
#else
|
||
dotlist[dotlen++] = '.';
|
||
dotlist[dotlen++] = '.';
|
||
dotlist[dotlen] = '\0';
|
||
parent_status = __lstat64_time64 (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_time64 (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_time64 (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
|