comment on

I want to use the Safe Module in an application which will load configuration files with methods. I don't require security but the other Safe Module features such as method sharing in either direction are very useful.

However, I've discovered some problems when trying to use other perl modules in the configuration files (e.g. File::Copy) and some standard Perl features don't work properly (e.g. glob).

I wondered if any of the monks or lay preachers might be able to advise.

Thanks in advance,

tgg

P.S. Hope formatting OK - 1st submission.

P.P.S. Added read more tags.

My Test Code example below demonstrates the problem with glob and a horrible workaround, which I hope will provide some clue as to what is going on.

In order to reproduce the results just paste the code into 3 files (SafeGlobDemo.pl, rdo.pl, glob.pl) as indicated.

Updated on August 3rd, 2008.

Added File::Copy Example as well. In order to reproduce the results just paste the code into 2 files (SafeCopyDemo.pl, rdo.pl) as indicated.

Updated again on August 3rd, 2008.

Just to let you know I've just sent perl bug reports on this issue, in case anyone spends a lot of time in it.


# Begin File: SafeGlobDemo.pl
#
use strict;
use warnings;

use Safe;

print "Running SafeGlobDemo\n";

do_list_files('*');


sub some_sub
{
}

sub do_list_files
{
    my $filespec = shift;
    print "do_list_files: Listing $filespec\n";
    my $cpt = load_compartment(__PACKAGE__, 'some_sub');

    if (defined($cpt) && exists &{$cpt->varglob('list_files')})
    {
        print "do_list_files: Calling rdo.pl list_files\n";
        &{$cpt->varglob('list_files')}($filespec);
    }
}

sub load_compartment
{
    my ($package, @subs) = @_;
    my $cpt;
    print "load_compartment\n";
    if (-f 'rdo.pl')
    {
        $cpt = new Safe;
        print "load_compartment: Doing rdo.pl\n";
        $cpt->share_from('main', [ '%ENV' ]);
        if (@ARGV > 0)
        {
            # Invoke horrible workaround!
            require 'glob.pl';
            $cpt->share_from('main', [ 'CORE::GLOBAL::glob' ]);
        }
        $cpt->share_from($package, [ @subs ]);
        $cpt->deny_only();
        $cpt->rdo('rdo.pl');
        if ($@)
        {
            die "Thrown exception from rdo.pl: $@\n";
        }
    }
    return $cpt;
}

# End File: SafeGlobDemo.pl

# Begin File: rdo.pl
#
use strict;
use warnings;

print "Loading rdo.pl\n";

sub list_files
{
    my $filespec = shift;

    for my $file (glob($filespec))
    {
        print "\tFound $file in rdo\n";
    }
}

# End File: rdo.pl

# Begin File: glob.pl
#
print "Loading glob.pl\n";

for (glob('*'))
{
   print ("\tFound $_\n");
}

1;

# End File: glob.pl

# End Code







# Test Results

# Begin Tests on Perl 5.10

# Test failure

C:\GLB\test\SafeGlobDemo>perl SafeGlobDemo.pl
Running SafeGlobDemo
do_list_files: Listing *
load_compartment
load_compartment: Doing rdo.pl
Thrown exception from rdo.pl: Undefined subroutine &Internals::SvREADO
+NLY called at C:/Perl/lib/constant.pm line 111.
BEGIN failed--compilation aborted at C:/Perl/lib/ActiveState/Path.pm l
+ine 11.
Compilation failed in require at C:/Perl/lib/ActivePerl/Config.pm line
+ 46.
Compilation failed in require at C:/Perl/lib/XSLoader.pm line 104.
Compilation failed in require at rdo.pl line 10.
BEGIN failed--compilation aborted at rdo.pl line 10.

# Workaround

C:\GLB\test\SafeGlobDemo>perl SafeGlobDemo.pl xxx
Running SafeGlobDemo
do_list_files: Listing *
load_compartment
load_compartment: Doing rdo.pl
Loading glob.pl
        Found glob.pl
        Found rdo.pl
        Found SafeGlobDemo.pl
Loading rdo.pl
do_list_files: Calling rdo.pl list_files
        Found glob.pl in rdo
        Found rdo.pl in rdo
        Found SafeGlobDemo.pl in rdo

C:\GLB\test\SafeGlobDemo>perl -v

This is perl, v5.10.0 built for MSWin32-x86-multi-thread
(with 5 registered patches, see perl -V for more detail)

Copyright 1987-2007, Larry Wall

Binary build 1003 [285500] provided by ActiveState http://www.ActiveSt
+ate.com
Built May 13 2008 16:52:49

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

# End Tests on Perl 5.10

# Begin Tests on Perl 5.8

# Test failure

D:\GLB\test\SafeGlobDemo>perl SafeGlobDemo.pl
Running SafeGlobDemo
do_list_files: Listing *
load_compartment
load_compartment: Doing rdo.pl
Thrown exception from rdo.pl: Can't locate object method "can" via pac
+kage "DynaLoader" at C:/Perl/lib/XSLoader.pm line 90.
Compilation failed in require at rdo.pl line 10.
BEGIN failed--compilation aborted at rdo.pl line 10.


# Workaround

D:\GLB\test\SafeGlobDemo>perl SafeGlobDemo.pl xxx
Running SafeGlobDemo
do_list_files: Listing *
load_compartment
load_compartment: Doing rdo.pl
Loading glob.pl
        Found glob.pl
        Found rdo.pl
        Found SafeGlobDemo.pl
Loading rdo.pl
do_list_files: Calling rdo.pl list_files
        Found glob.pl in rdo
        Found rdo.pl in rdo
        Found SafeGlobDemo.pl in rdo

D:\GLB\test\SafeGlobDemo>perl -v

This is perl, v5.8.8 built for MSWin32-x86-multi-thread
(with 18 registered patches, see perl -V for more detail)

Copyright 1987-2007, Larry Wall

Binary build 822 [280952] provided by ActiveState http://www.ActiveSta
+te.com
Built Jul 31 2007 19:34:48

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

# End Tests on Perl 5.8

# Begin File::Copy code

# File: SafeCopyDemo.pl
#
use strict;
use warnings;

use Safe;

print "Running SafeCopyDemo\n";

do_copy_file(@ARGV);


sub some_sub
{
}

sub do_copy_file
{
    if (@_ != 2)
    {
        print ("Usage: SafeCopyDemo.pl from_file to_file\n");
        return;
    }
    my ($from_filespec, $to_filespec) = @_;
    print "do_copy_file: Copying from $from_filespec to $to_filespec\n
+";
    my $cpt = load_compartment(__PACKAGE__, 'some_sub');

    if (defined($cpt) && exists &{$cpt->varglob('copy_file')})
    {
        print "do_copy_file: Calling rdo.pl copy_file\n";
        &{$cpt->varglob('copy_file')}($from_filespec, $to_filespec);
    }
}

sub load_compartment
{
    my ($package, @subs) = @_;
    my $cpt;
    print "load_compartment\n";
    if (-f 'rdo.pl')
    {
        $cpt = new Safe;
        print "load_compartment: Doing rdo.pl\n";
        $cpt->share_from('main', [ '%ENV' ]);
        $cpt->share_from($package, [ @subs ]);
        $cpt->deny_only();
        $cpt->rdo('rdo.pl');
        if ($@)
        {
            die "Thrown exception from rdo.pl: $@\n";
        }
    }
    return $cpt;
}

# File: rdo.pl
#
use strict;
use warnings;

use File::Copy;

print "Loading rdo.pl\n";

sub copy_file
{
    my ($from_filespec, $to_filespec) = @_;

    copy ($from_filespec, $to_filespec);

    print "\tCopied $from_filespec to $to_filespec\n";
}

# End File::Copy code

# Begin File::Copy Test on Perl 5.8

Running SafeCopyDemo
do_copy_file: Copying from XXX to YYY
load_compartment
load_compartment: Doing rdo.pl
Loading rdo.pl
do_copy_file: Calling rdo.pl copy_file
Unable to create sub named "*Config::launcher" at C:/Perl/lib/Config.p
+m line 71.

# End File::Copy Test on Perl 5.8
[download]

In reply to Problem globbing in Safe compartments - and other habits by tggbiz

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		`&`
	<		`<`
	>		`>`
	[		`[`
	]		`]`

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.