sub untaint($) {
  my $tainted = shift;
  my @untaintedbits;
  foreach (split //, $tainted) {
    if (m%([-\@\w.])%) {
      push @untaintedbits, $1;
    }
  }
  return join '', @untaintedbits;
}
sub untaintunixpath($) {
  my $tainted = shift;
  my @dirs = split '/', $tainted;
  map { $_ = untaint($_) } @dirs;
  return join '/', @dirs;
}
sub untaintstring($) {
  my $tainted = shift;
  my @words = split /\s+/, $tainted;
  map { $_ = untaint($_) } @words;
  return join ' ', @words;
}
my $res = GetOptions("help" => \$help, "unlock" => \$unlock, "vob=s" => \$vob,
		     "nusers=s" => \@nusers, "lbtype=s" => \@lbtype);
usage if $help or !($res and $vob and @lbtype) or ($unlock and @nusers);
@lbtype = split(/,/, join(',', @lbtype));
map { $_ = untaint($_) } @lbtype;
$vob = untaintunixpath($vob);
$vob = $ct->argv(qw(des -s), "vob:$vob")->qx;
die "Couldn't find the vob $vob\n" unless $vob;
$vob = untaintunixpath($vob);
my $pwnam = (getpwuid($<))[6];
$pwnam =~ s/^ *(.*[^ ]) *$/$1/;
$pwnam = untaintstring($pwnam);