Reject an empty name

Yep, just me testing more boundary conditions; this is another
one that ends up with a corrupted erofs. Reject empty filenames
in both the shared library and the C parser.

Signed-off-by: Colin Walters <[email protected]>

libcomposefs/lcfs-writer.c

@@ -1132,7 +1132,12 @@ int lcfs_node_add_child(struct lcfs_node_s *parent, struct lcfs_node_s *child,
 		return -1;
 	}
 
-	if (strlen(name) > LCFS_MAX_NAME_LENGTH) {
+	const size_t namelen = strlen(name);
+	if (namelen == 0) {
+		errno = EINVAL;
+		return -1;
+	}
+	if (namelen > LCFS_MAX_NAME_LENGTH) {
 		errno = ENAMETOOLONG;
 		return -1;
 	}

tests/assets/should-fail-empty-name.dump

@@ -0,0 +1,2 @@
+/ 4096 40555 2 0 0 0 1633950376.0 - - -
+// 4096 40555 2 0 0 0 1633950376.0 - - -

tests/meson.build

@@ -15,6 +15,7 @@ test_assets_should_fail = [
   'should-fail-long-xattr-key.dump',
   'should-fail-long-xattr-value.dump',
   'should-fail-no-ftype.dump',
+  'should-fail-empty-name.dump',
 ]
 
 test_assets = test_assets_small + [

tools/mkcomposefs.c

@@ -414,6 +414,9 @@ static char *tree_from_dump_line(dump_info *info, const char *line, size_t line_
 		fields[FIELD_PATH].data, fields[FIELD_PATH].len, NULL, &err);
 	if (path == NULL && err)
 		return err;
+	if (!*path) {
+		return make_error("Invalid empty path");
+	}
 
 	bool is_hardlink = false;
 	/* First char in mode is @ if hardlink */