in reply to Executing code block in memory

From my perspective, it would be easier to just redirect STDERR to STDOUT (or perhaps to an in-memory scalar), since warnings bypass the normal $@ error capture in eval. There are instructions for redirecting STDERR in open. You could also modify the $SIG{__WARN__} handler (see %SIG in perlvar). Or, as long as you've tossed security to the wind, maybe you could achieve your goal with CGI::Carp  qw(fatalsToBrowser);?

#11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

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Re^2: Executing code block in memory
by morissette (Novice) on Aug 08, 2012 at 21:39 UTC
    I tried this but I dont think its everything you were talking about: 
    #!/usr/bin/perl -w
use URI::Escape;
use HTML::Entities;
use CGI qw/:standard/;
print "Content-type: text/html\n\n";
my $file;
if(param('test')){
        my $code = param('test');
        $code = uri_unescape($code);
        $code = encode_entities($code);
        open STDERR, '>&STDOUT';
                open my $fh, '>', \$file;
                print $fh $code;
                close $fh;
                open my $pipe, '-|', "perl -w $file";
                close $pipe;
        close STDERR;
}

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    The output I get with this is: 
    sh: -c: line 0: syntax error near unexpected token `;;'
sh: -c: line 0: `perl -w print "hi";'

    [download]
    This is what is passed to the script: 
    print "hi";
print "hello world\n";

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[reply]
[d/l]
[select]
      A modified version of your sample that does what I mean: 
      #!/usr/bin/perl -w
use strict;

use URI::Escape;
use HTML::Entities;
use CGI qw/:standard/;
use CGI::Carp 'fatalsToBrowser';

print header;

my $file;
if(param('test')){
        my $code = param('test');
        $code = uri_unescape($code);
        $code = encode_entities($code);
        open STDERR, '>&STDOUT';
        eval $code;
        print $@ if $@;
}

      [download]

      No need to create external, temporary files. There are some potential messy issues in there, but this is good enough for rough cut.

      #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

[reply]
[d/l]

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