#!/usr/bin/perl -T

use strict; 
use warnings;
use v5.10;

use Scalar::Util;
use locale;
use POSIX qw(locale_h);
setlocale(LC_CTYPE, "de_DE");

sub filter_string {
  my $s = shift;

  warn("raw string '$s' is tainted") if Scalar::Util::tainted($s);
  $s =~ m:^(.+?) \([0-9]{4}(/[IVX]+)?\).*?$: or die "String '$s' doesn't match";
  $s = $1;
  warn("filtered string '$s' is tainted") if Scalar::Util::tainted($s);
  $s;
}

my @strings = ('ABC1 (1945/IXV)',
               'ABC2 (1945)',
               'ABC3 (1945)',
               'ABC4 (1945) {DEF()}',
               'ABC5 (1945) {D ()}',
               'ABC6 (1945) {D(#)}',
               'ABC7 (1945) {D (#)}',
               'ABC8 (1945) {()}',
               'ABC9 (1945) {D ()}',
               'ABC10 (1945) ()',
               'ABC11 (1945) {()',
               'ABC12 (1945) { ()}',
               'ABC13 (1945) { ()',
               'ABC14 (1945) x(/',
               'ABC15 (1945) ( ',
               'ABC16 (1945) (',
               'ABC17 (1945) { (',
               'ABC18 (1945) { (#',
  );

foreach my $s (@strings) {
  say filter_string($s);
}

filtered string 'ABC1' is tainted at ./check_taint.pl line 18.
ABC1
ABC2
ABC3
ABC4
filtered string 'ABC5' is tainted at ./check_taint.pl line 18.
ABC5
ABC6
filtered string 'ABC7' is tainted at ./check_taint.pl line 18.
ABC7
ABC8
filtered string 'ABC9' is tainted at ./check_taint.pl line 18.
ABC9
filtered string 'ABC10' is tainted at ./check_taint.pl line 18.
ABC10
ABC11
filtered string 'ABC12' is tainted at ./check_taint.pl line 18.
ABC12
filtered string 'ABC13' is tainted at ./check_taint.pl line 18.
ABC13
ABC14
filtered string 'ABC15' is tainted at ./check_taint.pl line 18.
ABC15
ABC16
ABC17
filtered string 'ABC18' is tainted at ./check_taint.pl line 18.
ABC18