adding getters in filesys.rs

src/filesys/filesys.rs

@@ -335,6 +335,16 @@ impl Filesys {
         //TODO
     }
 
+    /// return the free map file (used by the open file table).
+    pub fn get_free_map_file(self) -> OpenFile {
+        self.free_map_file
+    }
+
+    /// return the base directory file (used by the open file table).
+    pub fn get_dir_file(self) -> OpenFile {
+        self.directory_file
+    }
+
     /// Create a directory in the Nachos file system (similar to UNIX create).
     ///	A directory is a file containing a table of directory entries.
     ///