MODULE FioProg;
(* Self-hosted FileIO (runtime/syslib): write, read back, verify. *)
IMPORT FileIO;
FROM SYSTEM IMPORT ADDRESS;
VAR ExitCode : INTEGER;
VAR f : ADDRESS;
VAR buf : ARRAY [0..31] OF CHAR;
VAR n : CARDINAL;
BEGIN
  FileIO.Open(f, "gen_ssa/_fio_tmp.txt", TRUE);
  FileIO.WriteString(f, "hello");
  FileIO.WriteLn(f);
  FileIO.Close(f);

  FileIO.Open(f, "gen_ssa/_fio_tmp.txt", FALSE);
  n := LEN(buf);
  FileIO.ReadBytes(f, buf, n);
  FileIO.Close(f);

  IF (buf[0] = 'h') AND (n = 6) THEN ExitCode := n * 7 ELSE ExitCode := 0 END
END FioProg.