Problems with Safe compartment reval parameters

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

Hi,
I am fairly new to Perl and have been trying to use the Safe module to execute a perl script in a restricted compartment. There does not seem to be many (if any) examples of passing and retrieving parameters from the calling perl into the compartment. Anyhow I am having problems accessing variables passed into the compartment using the share method. My sample code is shown below and is a CGI script running through apache.

#!/usr/bin/perl -w
use Safe;
print "Content-type: text/html\n\n";

my %params = (
    key1 => 'value1',
    key2 => 'value2',
    key3 => 'value3',
);

# Run as a normal eval    
my $script = 'return $params{\'key1\'}';
my $ret = eval($script); warn $@ if $@;
print "ret=$ret<br>";
    
# Now run the script in a safe compartment
my $compartment = new Safe();
$compartment->share('%params');
$ret = $compartment->reval($script);
print "ret=$ret<br>";
[download]

The output in the browser window is shown below:

ret=value1
ret=
[download]

Showing that the compartment does not return the same result as the normal eval. Does anyone have any idea why this does not work.

Any help is appreciated

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Re: Problems with Safe compartment reval parameters by ikegami (Patriarch) on Sep 26, 2009 at 02:34 UTC
Aside from the missing `use Safe;`, share says "Each NAME must be the name of a non-lexical variable" (emphasis mine). You successfully shared `%main::params`, which isn't too useful since you never put a value in it.	[reply] [d/l] [select]
Re^2: Problems with Safe compartment reval parameters by winneymj (Initiate) on Sep 28, 2009 at 02:30 UTC
Just updated the code example to make it more clear the initialization of the hash. Thanks	[reply]
Re^3: Problems with Safe compartment reval parameters by GrandFather (Saint) on Sep 28, 2009 at 02:44 UTC
The important bit is that `my %params ...` declares a lexical variable. share only deals with package variables: `%params ...` which may make it less useful when strictures (use strict; use warnings;) are used (using strictures is highly recommended btw). True laziness is hard work	[reply] [d/l] [select]
Re^3: Problems with Safe compartment reval parameters by ikegami (Patriarch) on Sep 28, 2009 at 02:53 UTC
Yes, you are initialising a hash, but not the one the one you're sharing. `share` shares package variables — `%main::params` in this case — but you're initialising a lexical (`my`) variable. Change `my %params` to `local our %params`.	[reply] [d/l] [select]