my @files = <../data/text/*.txt>;
my @display_files = map /([^\/]+)\.txt/, @files;
Encode::from_to($_, "ISO-8859-7", "utf8") for @display_files;

print br;
print start_form( action=>'index.pl' );
    print h1( {class=>'lime'}, "&#917;&#960;&#941;&#955;&#949;&#958;&#
+949; &#964;&#959; &#954;&#949;&#943;&#956;&#949;&#957;&#959; &#960;&#
+959;&#965; &#963;&#949; &#949;&#957;&#948;&#953;&#945;&#966;&#941;&#9
+61;&#949;&#953; => ",
                                popup_menu( -name=>'select', -values=>
+\@display_files ),
                                submit('&#917;&#956;&#966;&#940;&#957;
+&#953;&#963;&#951;'));
print end_form;

my $passage = param('select') || "&#913;&#961;&#967;&#953;&#954;&#942;
+ &#931;&#949;&#955;&#943;&#948;&#945;!";
Encode::from_to($passage, "utf8", "ISO-8859-7") if param();


if ( param('select') )
{
    unless ( $passage =~ /^[a-zA-Z&#945;-&#969;&#913;-&#937;0-9]+$/ )
    {
    print br() x 2;
    print h1( {class=>'big'},  "*Backward Directory Traversal* hack wi
+ll NOT help you here, Mighty Lamer!" );
        exit;
    }
    
    open(FILE, "<../data/text/$passage.txt") or die $!;
         local $/;
         $data = <FILE>;
    close(FILE);

    Encode::from_to($passage, "ISO-8859-7", "utf8");

    $select = $dbh->prepare( "UPDATE guestlog SET passage=?, date=?, c
+ounter=counter+1 WHERE host=?" );
    $select->execute( $passage, $date, $host );
}
else
[download]

since I don't know what's in <../data/text/*.txt>, I have no clue what's going on.

In any case, since you're building that list anyway, why not do this:

if (grep { $_ eq $passage } @display_files) {
  # filename ok
}
else {
  # not ok
}
[download]

"What should it profit a man, if he should win a flame war, yet lose his cool?"

In <../data/text/*.txt> there iare all the text files index.pl will use and they are loaded in array display_files: This till didtn work:

if ( param('select') )
{
    unless (grep { $_ eq $passage } @display_files)
    {
    print br() x 2;
    print h1( {class=>'big'},  "*Backward Directory Traversal* hack wi
+ll NOT help you here, Mighty Lamer!" );
    
     $select = $dbh->prepare( "UPDATE guestlog SET passage=?, date=?, 
+counter=counter+1 WHERE host=?" );
    $select->execute( $passage, $date, $host );
    
        exit;
    }
[download]