nested Safe->reval and method from custom Module

[jeremyh]

Hello Monks,

I'm using Safe->reval to check if a generated perl expression is true.
I want to allow that perl expression to use a method from a custom perl module.
This method also uses Safe->reval (in a new compartment).
I can't get the nested reval to work (it works fine if called directly).

Here is the code:

The method in the custom module WOU_Util

my $compartment = new Safe;  # module level

$compartment->permit(qw());  # module level

sub date_compare {
    my ($date, $op, $refdate) = @_;

    my ($mm_date, $dd_date, $yyyy_date) = split(/\//, $date);
    my ($mm_ref, $dd_ref, $yyyy_ref) = split(/\//, $refdate);

    my $date_str = $yyyy_date . $mm_date . $dd_date;
    my $ref_str  = $yyyy_ref  . $mm_ref  . $dd_ref;

    $compartment->reval( qq{
        ($date_str $op $ref_str) || return 0;

         # fall-through
         return 1;
    } );
}

And here's some test code that calls the method:

#!/usr/bin/perl -w

use strict;
use Safe;
use WOU_Util;

my $compartment = new Safe;


$compartment->share_from('WOU_Util', [ 'date_compare' ] );
$compartment->permit( qw() );
  
my ($date1, $op, $date2);

$date1 = '01/02/2004';
$date2 = '01/01/2004';
$op    = 'gt';

# this prints
$compartment->reval( "print 'greater' if \"$date1\" $op \"$date2\"" );

$op = '>';
# this doesn't print, throws error
$compartment->reval( "print 'greater' if date_compare(\"$date1\",\"$op
+\",\"$date2\")" );

The error is:
Use of uninitialized value in null operation at /usr/lib/perl5/5.6.1/i386-linux/Safe.pm line 222.
(in cleanup) Undefined subroutine &Safe::Root0:: called at /usr/lib/perl5/5.6.1/i386-linux/Safe.pm line 222.

[gmpassos]

The permit() method allow new operators over the already allowed list of operators, so, permit(qw()) does nothing.

If you want to permit all you should use deny_only() without arguments, that will allow everything.

[jeremyh]

Answered my own question thanks to a hint from samtregar about eval and $@ (on a different thread!).
It needed

$compartment->permit( qw( entereval ) );


the nested eval was trapped by the opcode mask of the first eval.

[jeremyh]

Thanks, I discovered that the other day when I was reading the documentation.

What I had wanted was to deny everything so I guess I want permit_only