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

I am trying to use Safe

Strangely, with the ":base_core" ops allowed, numeric constants cause a 'ref-to-glob cast' to be trapped. I am assuming I need to permit another op.

I have made the following test code to demonstrate the problem:

#!perl
use strict;
use warnings;

use Safe;
my $box = new Safe;
$box->permit_only(':base_core');

my $vi = $box->reval('5',1);
die "$@ " unless (defined $vi);
print "vi=$vi\n";

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Which die'd with the messaged 'ref-to-glob cast' trapped by operation mask at (eval 6) line 1.

Replies are listed 'Best First'.
Re: What additional ops needed for Safe::reval ?
by stevieb (Canon) on Feb 09, 2017 at 19:56 UTC

    I've never used Safe before, but I thought I'd take a crack.

    After I figured out which opcode is for the error (rv2gv, which is in :base_orig), I was getting:

    'private value' trapped by operation mask...

    [download]

    So I found out which one took care of that (padany also in :base_orig):

    use strict;
use warnings;

use Safe;
my $box = new Safe;

$box->permit_only(
    ':base_core', 
    'rv2gv',      # ref to glob cast
    'padany'      # private variable
);

my $vi = $box->reval('5',1);
die "$@ " unless (defined $vi);
print "vi=$vi\n";

    [download]

    Output:

    vi=5

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    Note that the above can be simplified at the cost of allowing a bunch more opcodes implicitly:

    $box->permit_only(':base_core', ':base_orig');

    [download]

    While doing some searching after figuring out the solution, I came across this: Perl opcode list.

[reply]
[d/l]
[select]
Re: What additional ops needed for Safe::reval ? (why)
by Anonymous Monk on Feb 10, 2017 at 01:52 UTC
[reply]

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