I would like to allow my web users to execute little perl calculator programs: they could enter into my webform textarea field something like:

sub cubed { return $_[0]**3; }
$a=3 ;
25+$a**2 + cubed($a)

[download]

when the user hits submit, my server-side cgi script executes this snippet to learn that the user wanted '61'. later, the server will (eventually) return an html page that says "the result of your program {spit back what the user entered above} is 61." I want to predefine a few functions for the user myself, too, such as squared, cubed, etc., but still allow my own users to define their functions, too.

obviously, I do not want my users to inject nasty code, either into the html [I spit back what they entered); or worse, locally escape into my system (via system, backquote, or other nastily crafted entries.

so, I need a safe, sanitized subset version of perl that I can execute. I am probably not the first one in need of this, but I was hoping that someone could point me to where this has been put together already.

I could live with a non-perl syntax for my users, too, as long as it allows them to define their own functions and is reasonably safe. since my cgi server script is in perl, perl-like syntax may be advantageous.

pointers appreciated.

In reply to embedding a safe unescapable mini perl interpreter? by iaw4

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