sub topdir {
  my($nd,$parent)=@_;
  my $d = $nd;

  # Hack; strip off trailing characters that might be directory
  # seperators
  $parent =~ s/\W$//;

  while ($nd ne $parent)
  {
    $d = $nd;
    $nd = File::Basename::dirname($d);
  }

  return $d;
}