libmount: be robust when work with loopdev backing file paths

It's usually unnecessary as we compare devno and ino, but let's
use absolute paths for situations when it's necessary to compare
paths as strings.

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

2 files changed, 17 insertions, 18 deletions

diff --git a/libmount/src/context_loopdev.c b/libmount/src/context_loopdev.c
index 37fadb70..44a7216b 100644
--- a/libmount/src/context_loopdev.c
+++ b/libmount/src/context_loopdev.c
@@ -86,6 +86,8 @@ is_mounted_same_loopfile(struct libmnt_context *cxt,
 	struct libmnt_iter itr;
 	struct libmnt_fs *fs;
 	struct libmnt_cache *cache;
+	const char *bf;
+	int rc = 0;
 
 	assert(cxt);
 	assert(cxt->fs);
@@ -100,39 +102,36 @@ is_mounted_same_loopfile(struct libmnt_context *cxt,
 	cache = mnt_context_get_cache(cxt);
 	mnt_reset_iter(&itr, MNT_ITER_BACKWARD);
 
+	bf = cache ? mnt_resolve_path(backing_file, cache) : backing_file;
+
 	/* Search for a mountpoint node in mtab, proceed if any of these have the
 	 * loop option set or the device is a loop device
 	 */
-	while (mnt_table_next_fs(tb, &itr, &fs) == 0) {
+	while (rc == 0 && mnt_table_next_fs(tb, &itr, &fs) == 0) {
 		const char *src = mnt_fs_get_source(fs);
 		const char *opts = mnt_fs_get_user_options(fs);
 		char *val;
 		size_t len;
-		int res = 0;
 
 		if (!src || !mnt_fs_match_target(fs, target, cache))
 			continue;
 
+		rc = 0;
+
 		if (strncmp(src, "/dev/loop", 9) == 0) {
-			res = loopdev_is_used((char *) src, backing_file,
-					offset, LOOPDEV_FL_OFFSET);
+			rc = loopdev_is_used((char *) src, bf, offset, LOOPDEV_FL_OFFSET);
 
 		} else if (opts && (cxt->user_mountflags & MNT_MS_LOOP) &&
 		    mnt_optstr_get_option(opts, "loop", &val, &len) == 0 && val) {
 
 			val = strndup(val, len);
-			res = loopdev_is_used((char *) val, backing_file,
-					offset, LOOPDEV_FL_OFFSET);
+			rc = loopdev_is_used((char *) val, bf, offset, LOOPDEV_FL_OFFSET);
 			free(val);
 		}
-
-		if (res) {
-			DBG(CXT, mnt_debug_h(cxt, "%s already mounted", backing_file));
-			return 1;
-		}
 	}
-
-	return 0;
+	if (rc)
+		DBG(CXT, mnt_debug_h(cxt, "%s already mounted", backing_file));
+	return rc;
 }
 
 int mnt_context_setup_loopdev(struct libmnt_context *cxt)
diff --git a/libmount/src/context_umount.c b/libmount/src/context_umount.c
index b02902c4..2e912c0d 100644
--- a/libmount/src/context_umount.c
+++ b/libmount/src/context_umount.c
@@ -162,11 +162,9 @@ try_loopdev:
 
 		if (stat(tgt, &st) == 0 && S_ISREG(st.st_mode)) {
 			int count;
+			const char *bf = cache ? mnt_resolve_path(tgt, cache) : tgt;
 
-			cn_tgt = mnt_resolve_path(tgt, cache);
-			count = loopdev_count_by_backing_file(cn_tgt, &loopdev);
-			if (!cache)
-				free(cn_tgt);
+			count = loopdev_count_by_backing_file(bf, &loopdev);
 			if (count == 1) {
 				DBG(CXT, mnt_debug_h(cxt,
 					"umount: %s --> %s (retry)", tgt, loopdev));
@@ -361,7 +359,9 @@ static int evaluate_permissions(struct libmnt_context *cxt)
 		 */
 		fs = mnt_table_find_target(fstab, tgt, MNT_ITER_FORWARD);
 		if (fs) {
-			const char *dev = mnt_fs_get_srcpath(cxt->fs);		/* devname from mtab */
+			struct libmnt_cache *cache = mnt_context_get_cache(cxt);
+			const char *sp = mnt_fs_get_srcpath(cxt->fs);		/* devname from mtab */
+			const char *dev = sp && cache ? mnt_resolve_path(sp, cache) : sp;
 
 			if (!dev || !is_associated_fs(dev, fs))
 				fs = NULL;