That's confounding. I printed out the masks for both permit(qw(print readline)) and permit_only(qw(print readline)) using printf(): 
printf "%vd \n", $compartment->mask;

[download]

...and they are clearly different, which means a compartment allows some default operations that permit_only() must be erasing. Rereading the Safe docs, there is a set of default operations bundled under :default that are allowed. You have to check the Opcode docs to see which operations that :default includes. I'm not sure which ones I erased with permit_only() that are needed to reval() my sample code--but in any case it looks like if you want to use permit_only(), then you probably need a pretty good grasp of perl internals.

I did a bunch of trial and error, and to get permit_only() to work on my sample code, I need all these:

 $compartment->permit_only(qw(
        print 
        readline 
        :base_core   
        :base_mem
        :base_orig) 
);

[download]
The :default bundle of operations that a compartment allows consists of a bevy of other bundles:

:base_core 
:base_mem 
:base_loop 
:base_orig 
:base_thread

See the Opcode docs for which operations are included in each of those bundles.

In reply to Re^3: Passing argument into STDIN inside safe.pm reval by 7stud
in thread Passing argument into STDIN inside safe.pm reval by gideondsouza

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