my ($given_login, $given_pw) = ($query->{l}, $query->{p});
for (@users) {
  if ($_->{login} =~ m{^\Q$given_login\E$} and
      $_->{pw} =~ m{^\Q$given_pw\E$}) {
    $logged_in_as = $given_login;
    last;
  }
}