char *
__getcwd (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 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 && errno != ENAMETOOLONG && 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 (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;
/* 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;
}
char *
__getcwd (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
};
#ifdef AT_FDCWD
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 *path;
register char *pathp;
struct stat st;
size_t allocated = size;
size_t used;
#if HAVE_PARTLY_WORKING_GETCWD && !defined AT_FDCWD
/* 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. */
# undef getcwd
path = getcwd (buf, size);
if (path || (errno != ERANGE && !is_ENAMETOOLONG (errno) && errno != ENOENT))
return path;
#endif
if (size == 0)
{
if (buf != NULL)
{
__set_errno (EINVAL);
return NULL;
}
allocated = BIG_FILE_NAME_LENGTH + 1;
}
if (buf == NULL)
{
path = malloc (allocated);
if (path == NULL)
return NULL;
}
else
path = buf;
pathp = path + allocated;
*--pathp = '\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;
/* Look at the parent directory. */
#ifdef AT_FDCWD
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 (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. */
#ifdef AT_FDCWD
dirstream = fdopendir (fd);
if (dirstream == NULL)
goto lose;
fd_needs_closing = false;
#else
dirstream = __opendir (dotlist);
if (dirstream == NULL)
goto lose;
dotlist[dotlen++] = '/';
#endif
/* Clear errno to distinguish EOF from error if readdir returns
NULL. */
__set_errno (0);
while ((d = __readdir (dirstream)) != NULL)
{
if (d->d_name[0] == '.' &&
(d->d_name[1] == '\0' ||
(d->d_name[1] == '.' && d->d_name[2] == '\0')))
continue;
if (MATCHING_INO (d, thisino) || mount_point)
{
int entry_status;
#ifdef AT_FDCWD
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);
}
strcpy (dotlist + dotlen, d->d_name);
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;
}
}
if (d == NULL)
{
if (errno == 0)
/* EOF on dirstream, which means that the current directory
has been removed. */
__set_errno (ENOENT);
goto lose;
}
else
{
size_t pathroom = pathp - path;
size_t namlen = _D_EXACT_NAMLEN (d);
if (pathroom <= 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 (path, allocated)))
goto memory_exhausted;
/* Move current contents up to the end of the buffer.
This is guaranteed to be non-overlapping. */
pathp = memcpy (tmp + allocated - (oldsize - pathroom),
tmp + pathroom,
oldsize - pathroom);
path = tmp;
}
}
pathp -= namlen;
memcpy (pathp, d->d_name, namlen);
*--pathp = '/';
}
thisdev = dotdev;
thisino = dotino;
}
if (dirstream && __closedir (dirstream) != 0)
{
dirstream = NULL;
goto lose;
}
if (pathp == &path[allocated - 1])
*--pathp = '/';
#ifndef AT_FDCWD
if (dotlist != dots)
free (dotlist);
#endif
used = path + allocated - pathp;
memmove (path, pathp, used);
if (buf == NULL && size == 0)
/* Ensure that the buffer is only as large as necessary. */
buf = realloc (path, used);
if (buf == NULL)
/* Either buf was NULL all along, or `realloc' failed but
we still have the original string. */
buf = path;
return buf;
memory_exhausted:
__set_errno (ENOMEM);
lose:
{
int save = errno;
if (dirstream)
__closedir (dirstream);
#ifdef AT_FDCWD
if (fd_needs_closing)
close (fd);
#else
if (dotlist != dots)
free (dotlist);
#endif
if (buf == NULL)
free (path);
__set_errno (save);
}
return NULL;
}
