perlquestion
jeremyh
Hello Monks,
<br><br>
I'm using Safe->reval to check if a generated perl expression is true. <br>
I want to allow that perl expression to use a method from a custom perl module. <br>
This method also uses Safe->reval (in a new compartment). <br>
I can't get the nested reval to work (it works fine if called directly). <br>
<br>
Here is the code:
<br>
<br>The method in the custom module WOU_Util
<br>
<code>
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;
} );
}
</code>
<br>
<br>
And here's some test code that calls the method:
<br>
<code>
#!/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\")" );
</code>
<br>
<br>
The error is:
<br>
Use of uninitialized value in null operation at /usr/lib/perl5/5.6.1/i386-linux/Safe.pm line 222.<br>
(in cleanup) Undefined subroutine &Safe::Root0:: called at /usr/lib/perl5/5.6.1/i386-linux/Safe.pm line 222.