Ejemplo n.º 1
0
static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *lc)
{
	struct libmnt_table *tb = NULL;
	int rc = 0;

	DBG(UPDATE, mnt_debug_h(upd, "%s: modify target", upd->filename));

	if (lc)
		rc = mnt_lock_file(lc);
	if (rc)
		return rc;

	tb = __mnt_new_table_from_file(upd->filename,
			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
	if (tb) {
		struct libmnt_fs *cur = mnt_table_find_target(tb,
				mnt_fs_get_srcpath(upd->fs), MNT_ITER_BACKWARD);
		if (cur) {
			rc = mnt_fs_set_target(cur, mnt_fs_get_target(upd->fs));
			if (!rc)
				rc = update_table(upd, tb);
		}
	}

	if (lc)
		mnt_unlock_file(lc);

	mnt_free_table(tb);
	return rc;
}
Ejemplo n.º 2
0
static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
{
	struct libmnt_table *tb;
	int rc = 0;

	assert(upd);
	assert(upd->target);

	DBG(UPDATE, mnt_debug_h(upd, "%s: remove entry", upd->filename));

	if (lc)
		rc = mnt_lock_file(lc);
	if (rc)
		return rc;

	tb = __mnt_new_table_from_file(upd->filename,
			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
	if (tb) {
		struct libmnt_fs *rem = mnt_table_find_target(tb, upd->target, MNT_ITER_BACKWARD);
		if (rem) {
			mnt_table_remove_fs(tb, rem);
			rc = update_table(upd, tb);
			mnt_free_fs(rem);
		}
	}

	if (lc)
		mnt_unlock_file(lc);

	mnt_free_table(tb);
	return rc;
}
Ejemplo n.º 3
0
static int dir_to_device(const char *spec, dev_t *dev)
{
	struct libmnt_table *tb = mnt_new_table_from_file("/proc/self/mountinfo");
	struct libmnt_fs *fs;
	struct libmnt_cache *cache;
	int rc = -1;

	if (!tb) {
		/*
		 * Fallback. Traditional way to detect mountpoints. This way
		 * is independent on /proc, but not able to detect bind mounts.
		 */
		struct stat pst, st;
		char buf[PATH_MAX], *cn;
		int len;

		if (stat(spec, &st) != 0)
			return -1;

		cn = mnt_resolve_path(spec, NULL);	/* canonicalize */

		len = snprintf(buf, sizeof(buf), "%s/..", cn ? cn : spec);
		free(cn);

		if (len < 0 || (size_t) len + 1 > sizeof(buf))
			return -1;
		if (stat(buf, &pst) !=0)
			return -1;

		if ((st.st_dev != pst.st_dev) ||
		    (st.st_dev == pst.st_dev && st.st_ino == pst.st_ino)) {
			*dev = st.st_dev;
			return 0;
		}

		return -1;
	}

	/* to canonicalize all necessary paths */
	cache = mnt_new_cache();
	mnt_table_set_cache(tb, cache);

	fs = mnt_table_find_target(tb, spec, MNT_ITER_BACKWARD);
	if (fs && mnt_fs_get_target(fs)) {
		*dev = mnt_fs_get_devno(fs);
		rc = 0;
	}

	mnt_free_table(tb);
	mnt_free_cache(cache);
	return rc;
}
Ejemplo n.º 4
0
static int dir_to_device(struct mountpoint_control *ctl)
{
	struct libmnt_table *tb = mnt_new_table_from_file(_PATH_PROC_MOUNTINFO);
	struct libmnt_fs *fs;
	struct libmnt_cache *cache;
	int rc = -1;

	if (!tb) {
		/*
		 * Fallback. Traditional way to detect mountpoints. This way
		 * is independent on /proc, but not able to detect bind mounts.
		 */
		struct stat pst;
		char buf[PATH_MAX], *cn;
		int len;

		cn = mnt_resolve_path(ctl->path, NULL);	/* canonicalize */

		len = snprintf(buf, sizeof(buf), "%s/..", cn ? cn : ctl->path);
		free(cn);

		if (len < 0 || (size_t) len >= sizeof(buf))
			return -1;
		if (stat(buf, &pst) !=0)
			return -1;

		if ((ctl->st.st_dev != pst.st_dev) ||
		    (ctl->st.st_dev == pst.st_dev && ctl->st.st_ino == pst.st_ino)) {
			ctl->dev = ctl->st.st_dev;
			return 0;
		}

		return -1;
	}

	/* to canonicalize all necessary paths */
	cache = mnt_new_cache();
	mnt_table_set_cache(tb, cache);
	mnt_unref_cache(cache);

	fs = mnt_table_find_target(tb, ctl->path, MNT_ITER_BACKWARD);
	if (fs && mnt_fs_get_target(fs)) {
		ctl->dev = mnt_fs_get_devno(fs);
		rc = 0;
	}

	mnt_unref_table(tb);
	return rc;
}
Ejemplo n.º 5
0
static char *dir_to_device(const char *spec)
{
	struct libmnt_table *tb = mnt_new_table_from_file("/proc/self/mountinfo");
	struct libmnt_fs *fs;
	char *res = NULL;

	if (!tb)
		return NULL;

	fs = mnt_table_find_target(tb, spec, MNT_ITER_BACKWARD);
	if (fs && mnt_fs_get_target(fs))
		res = xstrdup(mnt_fs_get_source(fs));

	mnt_free_table(tb);
	return res;
}
Ejemplo n.º 6
0
int main (int argc, char *argv[])
{
	struct libmnt_fs *fs;
	struct libmnt_table *tab;

	mnt_init_debug(0xffff);

	tab = mnt_new_table_from_file("/proc/self/mounts");

	fs = mnt_table_find_target(tab, argv[2], MNT_ITER_BACKWARD);
	char *source = mnt_fs_get_source(fs);

	if (strcmp(source, argv[1]) == 0)
		printf("is mounted\n");
	else
		printf("could not find fs in tab\n");

	mnt_free_table(tab);

#if 0
	int rc;
	struct libmnt_fs *fs;
	struct libmnt_context *cxt = mnt_new_context();

	mnt_init_debug(0xffff);

	mnt_context_set_source(cxt, argv[1]);
	mnt_context_set_target(cxt, argv[2]);

	fs = mnt_context_get_fs(cxt);
	if (fs != NULL)
	{
		if (mnt_context_is_fs_mounted(cxt, fs, &rc))
			rc = 1;
		else
			printf("can't find fs in mtab\n");
	}
	else
		printf("Can't get fs from mnt context\n");

	mnt_free_context(cxt);
#endif

	return 0;
}
Ejemplo n.º 7
0
/*
 * See if device has been mounted by looking in mount table.  If so, set
 * device name and mount point name, and return 1, otherwise return 0.
 */
static int device_get_mountpoint(char **devname, char **mnt)
{
	struct libmnt_fs *fs;
	int rc;

	*mnt = NULL;

	if (!mtab) {
		mtab = mnt_new_table();
		if (!mtab)
			err(EXIT_FAILURE, _("failed to initialize libmount table"));

		cache = mnt_new_cache();
		mnt_table_set_cache(mtab, cache);

		if (p_option)
			rc = mnt_table_parse_file(mtab, _PATH_PROC_MOUNTINFO);
		else
			rc = mnt_table_parse_mtab(mtab, NULL);
		if (rc)
			err(EXIT_FAILURE, _("failed to parse mount table"));
	}

	fs = mnt_table_find_source(mtab, *devname, MNT_ITER_BACKWARD);
	if (!fs) {
		/* maybe 'devname' is mountpoint rather than a real device */
		fs = mnt_table_find_target(mtab, *devname, MNT_ITER_BACKWARD);
		if (fs) {
			free(*devname);
			*devname = xstrdup(mnt_fs_get_source(fs));
		}
	}

	if (fs) {
		*mnt = xstrdup(mnt_fs_get_target(fs));
		/* We'll call umount(), so remove the filesystem from the table
		 * to avoid duplicate results in the next device_get_mountpoint()
		 * call */
		mnt_free_fs(fs);
	}
	return *mnt ? 0 : -1;
}
Ejemplo n.º 8
0
/*
 * See if device has been mounted by looking in mount table.  If so, set
 * device name and mount point name, and return 1, otherwise return 0.
 */
static int device_get_mountpoint(char **devname, char **mnt)
{
	struct libmnt_fs *fs;
	int rc;

	*mnt = NULL;

	if (!mtab) {
		struct libmnt_cache *cache;

		mtab = mnt_new_table();
		if (!mtab)
			err(EXIT_FAILURE, _("failed to initialize libmount table"));

		cache = mnt_new_cache();
		mnt_table_set_cache(mtab, cache);
		mnt_unref_cache(cache);

		if (p_option)
			rc = mnt_table_parse_file(mtab, _PATH_PROC_MOUNTINFO);
		else
			rc = mnt_table_parse_mtab(mtab, NULL);
		if (rc)
			err(EXIT_FAILURE, _("failed to parse mount table"));
	}

	fs = mnt_table_find_source(mtab, *devname, MNT_ITER_BACKWARD);
	if (!fs) {
		/* maybe 'devname' is mountpoint rather than a real device */
		fs = mnt_table_find_target(mtab, *devname, MNT_ITER_BACKWARD);
		if (fs) {
			free(*devname);
			*devname = xstrdup(mnt_fs_get_source(fs));
		}
	}

	if (fs)
		*mnt = xstrdup(mnt_fs_get_target(fs));
	return *mnt ? 0 : -1;
}
Ejemplo n.º 9
0
static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *lc)
{
	struct libmnt_table *tb = NULL;
	int rc = 0;
	struct libmnt_fs *fs;

	assert(upd);
	assert(upd->fs);

	DBG(UPDATE, mnt_debug_h(upd, "%s: modify options", upd->filename));

	fs = upd->fs;

	if (lc)
		rc = mnt_lock_file(lc);
	if (rc)
		return rc;

	tb = __mnt_new_table_from_file(upd->filename,
			upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB);
	if (tb) {
		struct libmnt_fs *cur = mnt_table_find_target(tb,
					mnt_fs_get_target(fs),
					MNT_ITER_BACKWARD);
		if (cur) {
			if (upd->userspace_only)
				rc = mnt_fs_set_attributes(cur,	mnt_fs_get_attributes(fs));
			if (!rc)
				rc = mnt_fs_set_options(cur, mnt_fs_get_options(fs));
			if (!rc)
				rc = update_table(upd, tb);
		}
	}

	if (lc)
		mnt_unlock_file(lc);

	mnt_free_table(tb);
	return rc;
}
Ejemplo n.º 10
0
static int lookup_umount_fs(struct libmnt_context *cxt)
{
	int rc, loopdev = 0;
	const char *tgt;
	struct libmnt_table *mtab = NULL;
	struct libmnt_fs *fs;
	struct libmnt_cache *cache = NULL;
	char *cn_tgt = NULL;

	assert(cxt);
	assert(cxt->fs);

	DBG(CXT, mnt_debug_h(cxt, "umount: lookup FS"));

	tgt = mnt_fs_get_target(cxt->fs);
	if (!tgt) {
		DBG(CXT, mnt_debug_h(cxt, "umount: undefined target"));
		return -EINVAL;
	}

	/*
	 * The mtab file maybe huge and on systems with utab we have to merge
	 * userspace mount options into /proc/self/mountinfo. This all is
	 * expensive. The mtab filter allows to filter out entries, then
	 * mtab and utab are very tiny files.
	 *
	 * *but*... the filter uses mnt_fs_streq_{target,srcpath} functions
	 * where LABEL, UUID or symlinks are to canonicalized. It means that
	 * it's usable only for canonicalized stuff (e.g. kernel mountinfo).
	 */
	if (!cxt->mtab_writable	&& *tgt == '/' &&
	    !mnt_context_is_force(cxt) && !mnt_context_is_lazy(cxt)) {

		struct stat st;

		if (stat(tgt, &st) == 0 && S_ISDIR(st.st_mode)) {
			/* we'll canonicalized /proc/self/mountinfo */
			cache = mnt_context_get_cache(cxt);
			cn_tgt = mnt_resolve_path(tgt, cache);
			if (cn_tgt)
				mnt_context_set_tabfilter(cxt, mtab_filter, cn_tgt);
		}
	}
	rc = mnt_context_get_mtab(cxt, &mtab);

	if (cn_tgt) {
		mnt_context_set_tabfilter(cxt, NULL, NULL);
		if (!cache)
			free(cn_tgt);
	}

	if (rc) {
		DBG(CXT, mnt_debug_h(cxt, "umount: failed to read mtab"));
		return rc;
	}

try_loopdev:
	fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
	if (!fs && mnt_context_is_swapmatch(cxt)) {
		/*
		 * Maybe the option is source rather than target (sometimes
		 * people use e.g. "umount /dev/sda1")
		 */
		fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);

		if (fs) {
			struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
							mnt_fs_get_target(fs),
							MNT_ITER_BACKWARD);
			if (!fs1) {
				DBG(CXT, mnt_debug_h(cxt, "mtab is broken?!?!"));
				return -EINVAL;
			}
			if (fs != fs1) {
				/* Something was stacked over `file' on the
				 * same mount point. */
				DBG(CXT, mnt_debug_h(cxt,
						"umount: %s: %s is mounted "
						"over it on the same point",
						tgt, mnt_fs_get_source(fs1)));
				return -EINVAL;
			}
		}
	}

	if (!fs && !loopdev && mnt_context_is_swapmatch(cxt)) {
		/*
		 * Maybe the option is /path/file.img, try to convert to /dev/loopN
		 */
		struct stat st;

		if (stat(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
			char *dev = NULL;
			int count = loopdev_count_by_backing_file(tgt, &dev);

			if (count == 1) {
				DBG(CXT, mnt_debug_h(cxt,
					"umount: %s --> %s (retry)", tgt, dev));
				mnt_fs_set_source(cxt->fs, tgt);
				mnt_fs_set_target(cxt->fs, dev);
				free(dev);
				tgt = mnt_fs_get_target(cxt->fs);

				loopdev = 1;		/* to avoid endless loop */
				goto try_loopdev;

			} else if (count > 1)
				DBG(CXT, mnt_debug_h(cxt,
					"umount: warning: %s is associated "
					"with more than one loopdev", tgt));
		}
	}

	if (!fs) {
		DBG(CXT, mnt_debug_h(cxt, "umount: cannot find %s in mtab", tgt));
		return 0;
	}

	if (fs != cxt->fs) {
		/* copy from mtab to our FS description
		 */
		mnt_fs_set_source(cxt->fs, NULL);
		mnt_fs_set_target(cxt->fs, NULL);

		if (!mnt_copy_fs(cxt->fs, fs)) {
			DBG(CXT, mnt_debug_h(cxt, "umount: failed to copy FS"));
			return -errno;
		}
		DBG(CXT, mnt_debug_h(cxt, "umount: mtab applied"));
	}

	cxt->flags |= MNT_FL_TAB_APPLIED;
	return rc;
}
Ejemplo n.º 11
0
/*
 * Note that cxt->fs contains relevant mtab entry!
 */
static int evaluate_permissions(struct libmnt_context *cxt)
{
	struct libmnt_table *fstab;
	unsigned long u_flags = 0;
	const char *tgt, *src, *optstr;
	int rc, ok = 0;
	struct libmnt_fs *fs;

	assert(cxt);
	assert(cxt->fs);
	assert((cxt->flags & MNT_FL_MOUNTFLAGS_MERGED));

	if (!cxt || !cxt->fs)
		return -EINVAL;

	if (!mnt_context_is_restricted(cxt))
		 return 0;		/* superuser mount */

	DBG(CXT, mnt_debug_h(cxt, "umount: evaluating permissions"));

	if (!(cxt->flags & MNT_FL_TAB_APPLIED)) {
		DBG(CXT, mnt_debug_h(cxt,
				"cannot find %s in mtab and you are not root",
				mnt_fs_get_target(cxt->fs)));
		goto eperm;
	}

	if (cxt->user_mountflags & MNT_MS_UHELPER) {
		/* on uhelper= mount option based helper */
		rc = prepare_helper_from_options(cxt, "uhelper");
		if (rc)
			return rc;
		if (cxt->helper)
			return 0;	/* we'll call /sbin/umount.<uhelper> */
	}

	/*
	 * User mounts has to be in /etc/fstab
	 */
	rc = mnt_context_get_fstab(cxt, &fstab);
	if (rc)
		return rc;

	tgt = mnt_fs_get_target(cxt->fs);
	src = mnt_fs_get_source(cxt->fs);

	if (mnt_fs_get_bindsrc(cxt->fs)) {
		src = mnt_fs_get_bindsrc(cxt->fs);
		DBG(CXT, mnt_debug_h(cxt,
				"umount: using bind source: %s", src));
	}

	/* If fstab contains the two lines
	 *	/dev/sda1 /mnt/zip auto user,noauto  0 0
	 *	/dev/sda4 /mnt/zip auto user,noauto  0 0
	 * then "mount /dev/sda4" followed by "umount /mnt/zip" used to fail.
	 * So, we must not look for file, but for the pair (dev,file) in fstab.
	  */
	fs = mnt_table_find_pair(fstab, src, tgt, MNT_ITER_FORWARD);
	if (!fs) {
		/*
		 * It's possible that there is /path/file.img in fstab and
		 * /dev/loop0 in mtab -- then we have to check releation
		 * between loopdev and the file.
		 */
		fs = mnt_table_find_target(fstab, tgt, MNT_ITER_FORWARD);
		if (fs) {
			const char *dev = mnt_fs_get_srcpath(cxt->fs);		/* devname from mtab */

			if (!dev || !is_associated_fs(dev, fs))
				fs = NULL;
		}
		if (!fs) {
			DBG(CXT, mnt_debug_h(cxt,
					"umount %s: mtab disagrees with fstab",
					tgt));
			goto eperm;
		}
	}

	/*
	 * User mounting and unmounting is allowed only if fstab contains one
	 * of the options `user', `users' or `owner' or `group'.
	 *
	 * The option `users' allows arbitrary users to mount and unmount -
	 * this may be a security risk.
	 *
	 * The options `user', `owner' and `group' only allow unmounting by the
	 * user that mounted (visible in mtab).
	 */
	optstr = mnt_fs_get_user_options(fs);	/* FSTAB mount options! */
	if (!optstr)
		goto eperm;

	if (mnt_optstr_get_flags(optstr, &u_flags,
				mnt_get_builtin_optmap(MNT_USERSPACE_MAP)))
		goto eperm;

	if (u_flags & MNT_MS_USERS) {
		DBG(CXT, mnt_debug_h(cxt,
			"umount: promiscuous setting ('users') in fstab"));
		return 0;
	}
	/*
	 * Check user=<username> setting from mtab if there is user, owner or
	 * group option in /etc/fstab
	 */
	if (u_flags & (MNT_MS_USER | MNT_MS_OWNER | MNT_MS_GROUP)) {

		char *curr_user = NULL;
		char *mtab_user = NULL;
		size_t sz;

		DBG(CXT, mnt_debug_h(cxt,
				"umount: checking user=<username> from mtab"));

		curr_user = mnt_get_username(getuid());

		if (!curr_user) {
			DBG(CXT, mnt_debug_h(cxt, "umount %s: cannot "
				"convert %d to username", tgt, getuid()));
			goto eperm;
		}

		/* get options from mtab */
		optstr = mnt_fs_get_user_options(cxt->fs);
		if (optstr && !mnt_optstr_get_option(optstr,
					"user", &mtab_user, &sz) && sz)
			ok = !strncmp(curr_user, mtab_user, sz);
	}

	if (ok) {
		DBG(CXT, mnt_debug_h(cxt, "umount %s is allowed", tgt));
		return 0;
	}
eperm:
	DBG(CXT, mnt_debug_h(cxt, "umount is not allowed for you"));
	return -EPERM;
}
Ejemplo n.º 12
0
/**
 * mnt_context_find_umount_fs:
 * @cxt: mount context
 * @tgt: mountpoint, device, ...
 * @pfs: returns point to filesystem
 *
 * Returns: 0 on success, <0 on error, 1 if target filesystem not found
 */
int mnt_context_find_umount_fs(struct libmnt_context *cxt,
			       const char *tgt,
			       struct libmnt_fs **pfs)
{
	int rc;
	struct libmnt_table *mtab = NULL;
	struct libmnt_fs *fs;
	char *loopdev = NULL;

	if (pfs)
		*pfs = NULL;

	if (!cxt || !tgt || !pfs)
		return -EINVAL;

	DBG(CXT, ul_debugobj(cxt, "umount: lookup FS for '%s'", tgt));

	if (!*tgt)
		return 1; /* empty string is not an error */

	/*
	 * The mount table may be huge, and on systems with utab we have to merge
	 * userspace mount options into /proc/self/mountinfo. This all is
	 * expensive. The tab filter allows to filter out entries, then
	 * a mount table and utab are very tiny files.
	 *
	 * *but*... the filter uses mnt_fs_streq_{target,srcpath} functions
	 * where LABEL, UUID or symlinks are canonicalized. It means that
	 * it's usable only for canonicalized stuff (e.g. kernel mountinfo).
	 */
	if (!mnt_context_mtab_writable(cxt) && *tgt == '/' &&
	    !mnt_context_is_force(cxt) && !mnt_context_is_lazy(cxt))
		rc = mnt_context_get_mtab_for_target(cxt, &mtab, tgt);
	else
		rc = mnt_context_get_mtab(cxt, &mtab);

	if (rc) {
		DBG(CXT, ul_debugobj(cxt, "umount: failed to read mtab"));
		return rc;
	}

	if (mnt_table_get_nents(mtab) == 0) {
		DBG(CXT, ul_debugobj(cxt, "umount: mtab empty"));
		return 1;
	}

try_loopdev:
	fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
	if (!fs && mnt_context_is_swapmatch(cxt)) {
		/*
		 * Maybe the option is source rather than target (sometimes
		 * people use e.g. "umount /dev/sda1")
		 */
		fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);

		if (fs) {
			struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
							mnt_fs_get_target(fs),
							MNT_ITER_BACKWARD);
			if (!fs1) {
				DBG(CXT, ul_debugobj(cxt, "mtab is broken?!?!"));
				rc = -EINVAL;
				goto err;
			}
			if (fs != fs1) {
				/* Something was stacked over `file' on the
				 * same mount point. */
				DBG(CXT, ul_debugobj(cxt,
						"umount: %s: %s is mounted "
						"over it on the same point",
						tgt, mnt_fs_get_source(fs1)));
				rc = -EINVAL;
				goto err;
			}
		}
	}

	if (!fs && !loopdev && mnt_context_is_swapmatch(cxt)) {
		/*
		 * Maybe the option is /path/file.img, try to convert to /dev/loopN
		 */
		struct stat st;

		if (mnt_stat_mountpoint(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
			int count;
			struct libmnt_cache *cache = mnt_context_get_cache(cxt);
			const char *bf = cache ? mnt_resolve_path(tgt, cache) : tgt;

			count = loopdev_count_by_backing_file(bf, &loopdev);
			if (count == 1) {
				DBG(CXT, ul_debugobj(cxt,
					"umount: %s --> %s (retry)", tgt, loopdev));
				tgt = loopdev;
				goto try_loopdev;

			} else if (count > 1)
				DBG(CXT, ul_debugobj(cxt,
					"umount: warning: %s is associated "
					"with more than one loopdev", tgt));
		}
	}

	if (pfs)
		*pfs = fs;
	free(loopdev);

	DBG(CXT, ul_debugobj(cxt, "umount fs: %s", fs ? mnt_fs_get_target(fs) :
							"<not found>"));
	return fs ? 0 : 1;
err:
	free(loopdev);
	return rc;
}
Ejemplo n.º 13
0
static int lookup_umount_fs(struct libmnt_context *cxt)
{
	int rc, loopdev = 0;
	const char *tgt;
	struct libmnt_table *mtab = NULL;
	struct libmnt_fs *fs;

	assert(cxt);
	assert(cxt->fs);

	DBG(CXT, mnt_debug_h(cxt, "umount: lookup FS"));

	tgt = mnt_fs_get_target(cxt->fs);
	if (!tgt) {
		DBG(CXT, mnt_debug_h(cxt, "umount: undefined target"));
		return -EINVAL;
	}
	rc = mnt_context_get_mtab(cxt, &mtab);
	if (rc) {
		DBG(CXT, mnt_debug_h(cxt, "umount: failed to read mtab"));
		return rc;
	}

try_loopdev:
	fs = mnt_table_find_target(mtab, tgt, MNT_ITER_BACKWARD);
	if (!fs) {
		/* maybe the option is source rather than target (mountpoint) */
		fs = mnt_table_find_source(mtab, tgt, MNT_ITER_BACKWARD);

		if (fs) {
			struct libmnt_fs *fs1 = mnt_table_find_target(mtab,
							mnt_fs_get_target(fs),
							MNT_ITER_BACKWARD);
			if (!fs1) {
				DBG(CXT, mnt_debug_h(cxt, "mtab is broken?!?!"));
				return -EINVAL;
			}
			if (fs != fs1) {
				/* Something was stacked over `file' on the
				 * same mount point. */
				DBG(CXT, mnt_debug_h(cxt,
						"umount: %s: %s is mounted "
						"over it on the same point",
						tgt, mnt_fs_get_source(fs1)));
				return -EINVAL;
			}
		}
	}

	if (!fs && !loopdev) {
		/*
		 * Maybe target is /path/file.img, try to convert to /dev/loopN
		 */
		struct stat st;

		if (stat(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
			char *dev = NULL;
			int count = loopdev_count_by_backing_file(tgt, &dev);

			if (count == 1) {
				DBG(CXT, mnt_debug_h(cxt,
					"umount: %s --> %s (retry)", tgt, dev));
				mnt_fs_set_source(cxt->fs, tgt);
				mnt_fs_set_target(cxt->fs, dev);
				free(dev);
				tgt = mnt_fs_get_target(cxt->fs);

				loopdev = 1;		/* to avoid endless loop */
				goto try_loopdev;

			} else if (count > 1)
				DBG(CXT, mnt_debug_h(cxt,
					"umount: warning: %s is associated "
					"with more than one loodev", tgt));
		}
	}

	if (!fs) {
		DBG(CXT, mnt_debug_h(cxt, "umount: cannot find %s in mtab", tgt));
		return 0;
	}

	if (fs != cxt->fs) {
		/* copy from mtab to our FS description
		 */
		mnt_fs_set_source(cxt->fs, NULL);
		mnt_fs_set_target(cxt->fs, NULL);

		if (!mnt_copy_fs(cxt->fs, fs)) {
			DBG(CXT, mnt_debug_h(cxt, "umount: failed to copy FS"));
			return -errno;
		}
		DBG(CXT, mnt_debug_h(cxt, "umount: mtab applied"));
	}

	cxt->flags |= MNT_FL_TAB_APPLIED;
	return rc;
}