MODULE TBadFile;
// A failed file open returns NIL; file operations on it must degrade
// safely (no SIGSEGV). The path below cannot be opened. Exit 42.
IMPORT Files;
VAR ExitCode : INTEGER;
VAR f : Files.File;
VAR n : INTEGER;
BEGIN
  f := Files.OpenWrite("no/such/dir/_t_badfile.txt");
  Files.WriteChar(f, 'x');      (* NIL handle: must be a no-op *)
  Files.WriteInt(f, 123);
  Files.Close(f);
  f := Files.OpenRead("no/such/dir/_t_badfile.txt");
  n := Files.ReadInt(f);        (* NIL handle: must return 0 *)
  Files.Close(f);
  ExitCode := 42
END TBadFile.