let id = ref 0

let rec go dir_name par_id =
  Unix.chdir dir_name;
  incr id;
  let id = !id in
  Printf.printf "D %d %d %s\n" id par_id dir_name;
  let d = Unix.opendir "." in
  let dirs = ref [] in
  let rec loop () =
    let f = Unix.readdir d in
    let st = Unix.lstat f in
    let _ =
      match f.[0], st.Unix.st_kind with
      | '.', _ -> ()
      | _, Unix.S_DIR -> dirs := f :: !dirs
      | _, Unix.S_REG -> Printf.printf "F %d %s\n" st.Unix.st_size f
      | _ -> ()
    in loop ()
  in
  begin
    List.iter (fun f -> go f id) 
      (try
        loop ()
       with End_of_file -> Unix.closedir d; !dirs)
  end;
  Unix.chdir ".."

let _ =
  Printf.printf "R 0 .\n";
  go "." 0