libmount: be robust for empty target/source strings

 * lib/canonicalize.c: don't interpret empty strings as relative paths
 * libmount: more robust libmnt_table find function and debug messages

References: https://bugzilla.novell.com/show_bug.cgi?id=825150
Signed-off-by: Karel Zak <kzak@redhat.com>

Signed-off-by: Karel Zak <kzak@redhat.com>

4 files changed, 36 insertions, 17 deletions

diff --git a/lib/canonicalize.c b/lib/canonicalize.c
index 727806e1e..548e29b75 100644
--- a/lib/canonicalize.c
+++ b/lib/canonicalize.c
@@ -151,6 +151,9 @@ canonicalize_dm_name(const char *ptname)
 	size_t	sz;
 	char	path[256], name[256], *res = NULL;
 
+	if (!ptname || !*ptname)
+		return NULL;
+
 	snprintf(path, sizeof(path), "/sys/block/%s/dm/name", ptname);
 	if (!(f = fopen(path, "r" UL_CLOEXECSTR)))
 		return NULL;
@@ -173,7 +176,7 @@ canonicalize_path(const char *path)
 	char canonical[PATH_MAX+2];
 	char *p;
 
-	if (path == NULL)
+	if (!path || !*path)
 		return NULL;
 
 	if (!myrealpath(path, canonical, PATH_MAX+1))
@@ -199,7 +202,7 @@ canonicalize_path_restricted(const char *path)
 	uid_t euid;
 	gid_t egid;
 
-	if (path == NULL)
+	if (!path || !*path)
 		return NULL;
 
 	euid = geteuid();
diff --git a/libmount/src/context_umount.c b/libmount/src/context_umount.c
index 4a8659c9c..7707991eb 100644
--- a/libmount/src/context_umount.c
+++ b/libmount/src/context_umount.c
@@ -71,11 +71,17 @@ int mnt_context_find_umount_fs(struct libmnt_context *cxt,
 	struct libmnt_cache *cache = NULL;
 	char *cn_tgt = NULL, *loopdev = NULL;
 
+	if (pfs)
+		*pfs = NULL;
+
 	if (!cxt || !tgt || !pfs)
 		return -EINVAL;
 
 	DBG(CXT, mnt_debug_h(cxt, "umount: lookup FS for '%s'", tgt));
 
+	if (!*tgt)
+		return 1; /* empty string is not error */
+
 	/*
 	 * The mtab file maybe huge and on systems with utab we have to merge
 	 * userspace mount options into /proc/self/mountinfo. This all is
@@ -169,9 +175,12 @@ try_loopdev:
 		}
 	}
 
-	*pfs = fs;
+	if (pfs)
+		*pfs = fs;
 	free(loopdev);
 
+	DBG(CXT, mnt_debug_h(cxt, "umount fs: %s", fs ? mnt_fs_get_target(fs) :
+							"<not found>"));
 	return fs ? 0 : 1;
 err:
 	free(loopdev);
@@ -197,7 +206,7 @@ static int lookup_umount_fs(struct libmnt_context *cxt)
 	if (rc < 0)
 		return rc;
 	if (rc == 1 || !fs) {
-		DBG(CXT, mnt_debug_h(cxt, "umount: cannot find %s in mtab", tgt));
+		DBG(CXT, mnt_debug_h(cxt, "umount: cannot find '%s' in mtab", tgt));
 		return 0;
 	}
 
diff --git a/libmount/src/tab.c b/libmount/src/tab.c
index 11a297814..ef86627f8 100644
--- a/libmount/src/tab.c
+++ b/libmount/src/tab.c
@@ -274,7 +274,7 @@ int mnt_table_next_child_fs(struct libmnt_table *tb, struct libmnt_iter *itr,
 	if (!tb || !itr || !parent)
 		return -EINVAL;
 
-	DBG(TAB, mnt_debug_h(tb, "lookup next child of %s",
+	DBG(TAB, mnt_debug_h(tb, "lookup next child of '%s'",
 				mnt_fs_get_target(parent)));
 
 	parent_id = mnt_fs_get_id(parent);
@@ -442,12 +442,12 @@ struct libmnt_fs *mnt_table_find_mountpoint(struct libmnt_table *tb,
 {
 	char *mnt;
 
-	if (!tb || !path)
+	if (!tb || !path || !*path)
 		return NULL;
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
 
-	DBG(TAB, mnt_debug_h(tb, "lookup MOUNTPOINT: %s", path));
+	DBG(TAB, mnt_debug_h(tb, "lookup MOUNTPOINT: '%s'", path));
 
 	mnt = strdup(path);
 	if (!mnt)
@@ -494,12 +494,12 @@ struct libmnt_fs *mnt_table_find_target(struct libmnt_table *tb, const char *pat
 	assert(tb);
 	assert(path);
 
-	if (!tb || !path)
+	if (!tb || !path || !*path)
 		return NULL;
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
 
-	DBG(TAB, mnt_debug_h(tb, "lookup TARGET: %s", path));
+	DBG(TAB, mnt_debug_h(tb, "lookup TARGET: '%s'", path));
 
 	/* native @target */
 	mnt_reset_iter(&itr, direction);
@@ -510,6 +510,8 @@ struct libmnt_fs *mnt_table_find_target(struct libmnt_table *tb, const char *pat
 	if (!tb->cache || !(cn = mnt_resolve_path(path, tb->cache)))
 		return NULL;
 
+	DBG(TAB, mnt_debug_h(tb, "lookup canonical TARGET: '%s'", cn));
+
 	/* canonicalized paths in struct libmnt_table */
 	mnt_reset_iter(&itr, direction);
 	while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
@@ -566,12 +568,12 @@ struct libmnt_fs *mnt_table_find_srcpath(struct libmnt_table *tb, const char *pa
 	const char *p;
 
 	assert(tb);
-	if (!tb || !path)
+	if (!tb || !path || !*path)
 		return NULL;
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
 
-	DBG(TAB, mnt_debug_h(tb, "lookup srcpath: %s", path));
+	DBG(TAB, mnt_debug_h(tb, "lookup SRCPATH: '%s'", path));
 
 	/* native paths */
 	mnt_reset_iter(&itr, direction);
@@ -585,6 +587,8 @@ struct libmnt_fs *mnt_table_find_srcpath(struct libmnt_table *tb, const char *pa
 	if (!path || !tb->cache || !(cn = mnt_resolve_path(path, tb->cache)))
 		return NULL;
 
+	DBG(TAB, mnt_debug_h(tb, "lookup canonical SRCPATH: '%s'", cn));
+
 	/* canonicalized paths in struct libmnt_table */
 	if (ntags < mnt_table_get_nents(tb)) {
 		mnt_reset_iter(&itr, direction);
@@ -672,7 +676,7 @@ struct libmnt_fs *mnt_table_find_tag(struct libmnt_table *tb, const char *tag,
 	assert(tag);
 	assert(val);
 
-	if (!tb || !tag || !val)
+	if (!tb || !tag || !*tag || !val)
 		return NULL;
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
@@ -721,9 +725,9 @@ struct libmnt_fs *mnt_table_find_source(struct libmnt_table *tb,
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
 
-	DBG(TAB, mnt_debug_h(tb, "lookup SOURCE: %s", source));
+	DBG(TAB, mnt_debug_h(tb, "lookup SOURCE: '%s'", source));
 
-	if (source && strchr(source, '=')) {
+	if (source && *source && strchr(source, '=')) {
 		char *tag, *val;
 
 		if (blkid_parse_tag_string(source, &tag, &val) == 0) {
@@ -761,7 +765,7 @@ struct libmnt_fs *mnt_table_find_pair(struct libmnt_table *tb, const char *sourc
 	assert(tb);
 	assert(target);
 
-	if (!tb || !target)
+	if (!tb || !target || !*target || !source || !*source)
 		return NULL;
 	if (direction != MNT_ITER_FORWARD && direction != MNT_ITER_BACKWARD)
 		return NULL;
@@ -841,7 +845,7 @@ struct libmnt_fs *mnt_table_get_fs_root(struct libmnt_table *tb,
 	assert(fs);
 	assert(fsroot);
 
-	DBG(TAB, mnt_debug("lookup fs-root for %s", mnt_fs_get_source(fs)));
+	DBG(TAB, mnt_debug("lookup fs-root for '%s'", mnt_fs_get_source(fs)));
 
 	fstype = mnt_fs_get_fstype(fs);
 
diff --git a/sys-utils/umount.c b/sys-utils/umount.c
index e3f0e2dd0..c3b8187ce 100644
--- a/sys-utils/umount.c
+++ b/sys-utils/umount.c
@@ -236,7 +236,10 @@ static int mk_exit_code(struct libmnt_context *cxt, int rc)
 			tgt);
 		break;
 	case ENOENT:
-		warnx(_("%s: not found"), tgt);
+		if (tgt && *tgt)
+			warnx(_("%s: mountpoint not found"), tgt);
+		else
+			warnx(_("undefined mountpoint"));
 		break;
 	case EPERM:
 		warnx(_("%s: must be superuser to unmount"), tgt);