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Work even in a chroot where d_ino values for entries in "/"

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don't match the stat.st_ino values for the same names.

(__getcwd): When no d_ino value matches the target inode
number, iterate through all entries again, using lstat instead.
Reported by Kenshi Muto in http://bugs.debian.org/355810.
This commit is contained in:
Jim Meyering 2006-03-19 18:27:51 +00:00
parent e233777dbe
commit 164d936ac2
1 changed files with 73 additions and 50 deletions
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123
lib/getcwd.c
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@ -211,6 +211,7 @@ __getcwd (char *buf, size_t size)
int parent_status;
size_t dirroom;
size_t namlen;
bool use_d_ino = true;
/* Look at the parent directory. */
#ifdef AT_FDCWD
@ -257,6 +258,21 @@ __getcwd (char *buf, size_t size)
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)
@ -269,58 +285,65 @@ __getcwd (char *buf, size_t size)
(d->d_name[1] == '\0' ||
(d->d_name[1] == '.' && d->d_name[2] == '\0')))
continue;
if (MATCHING_INO (d, thisino) || mount_point)
if (use_d_ino)
{
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);
}
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;
bool match = (MATCHING_INO (d, thisino) || mount_point);
if (! match)
continue;
}
{
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);
}
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;