use Safe and CGI;

Banky has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to create a CGI application that allows users to Safely eval some types of Perl code. Of course I need the Safe module to only allow a small subset of opcodes that are considered safe and useful for this application. Here's a test script I've been writing. It basically goes through and finds what opcodes $line needs to execute. It ex

#!/usr/bin/perl
use Opcode;
use Safe;
my @names = Opcode::opset_to_ops(Opcode::full_opset);
my @neededops;
use CGI;
my $query=CGI::new();
print $query->header();
print "<HTML><BODY>";
foreach $name(@names)
{
   my $cpt;
   $cpt=undef;
   $cpt=new Safe;
   $cpt->share('$name');
   my(@ops)=grep { $_ ne $name} @names;
   $cpt->permit_only(@ops);
   my $line=q{ print "Opcode: $name\n"; };
   $cpt->reval($line); 
   push @neededops, $name if $@;
}

print "<HR>\n\n@neededops\n";
print "</BODY></HTML>";
[download]

It works fine from the command line but when I run it through a browser I get a "The document contains no data" dialog box. If I comment out $cpt->reval($line) this disappears. Any ideas why this might be happening?
Thanks a lot,

Banky

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