io: fix null pointer deref in win32 update_iterator_data

io/sys/windows/directory.c

@@ -159,17 +159,18 @@ static void update_iterator_data(struct b_directory_iterator *it)
 	}
 
 	struct iteration_state *state = get_iteration_state(it->_z);
-	it->filename = state->data.cFileName;
+	if (state) {
+		it->filename = state->data.cFileName;
 
-	struct b_path *filename = b_path_create_from_cstr(it->filename);
+		struct b_path *filename = b_path_create_from_cstr(it->filename);
 
-	const struct b_path *parts[] = {
-		state->search_path,
-		filename,
-	};
+		const struct b_path *parts[] = {
+			state->search_path,
+			filename,
+		};
 
-	it->filepath
-		= b_path_join(parts, sizeof parts / sizeof parts[0]);
+		it->filepath = b_path_join(parts, sizeof parts / sizeof parts[0]);
+	}
 }
 
 static bool move_into_directory(struct b_directory_iterator *it, const char *dir_name)