Re^3: Use with variable

That's what I get for not testing my stuff :-((

So it seems the only actually working way is the ugly way of converting the module name to the file name and then requiring that file :

my $module = "CGI";
my $filename = $module;
$filename =~ s!::!/!g;
$filename .= ".pm";
require $filename
  or die "$module did not return a true value";
$module->import;
[download]

(this time tested it ...)

Comment on Re^3: Use with variable Download Code

Replies are listed 'Best First'.
Re^4: Use with variable by edan (Curate) on Sep 08, 2004 at 13:42 UTC
Do you have something against eval? I think that's the most straightforward solution... -- edan	[reply]
Re^5: Use with variable by Corion (Patriarch) on Sep 08, 2004 at 13:48 UTC
I try to avoid string-eval wherever I can, because I don't like the security implications of it. Of course, it's unlikely that a module name like `CGI; qx(rm -rf /)` `can be injected, but with my solution that gets avoided completely. Of course, this is most likely total overkill, as in most cases, modules are loaded dynamically upon program startup depending on the OS.`	[reply]
Re^6: Use with variable by edan (Curate) on Sep 08, 2004 at 14:15 UTC
You make an excellent point about the dangers of string-eval. Of course you need to de-taint the module-name before you eval it. Perhaps something like the following would help to assuage your fears? `#!perl -T use strict; use warnings; # flame-resistant print "module: "; chomp(my $module = <STDIN>); if ( $module =~ /^([A-Za-z0-9_:]+)$/ ) { $module = $1; } else { die "Can't use $module: hack off, buddy!"; } eval "use $module"; print "game over ($@)" if $@; print "all clear\n";` [download] The verbosity certainly rivals the package-name-to-file-name twiddling that you had to do, so neither way is preferable... :) -- edan	[reply] [d/l]
Re^6: Use with variable by Anonymous Monk on Sep 08, 2004 at 14:43 UTC
Eh, considering that a use or a require does an eval, what exactly are you trying to protect yourself from? If a user can pass a module name of his choosing, you're doomed anyway, no matter what restrictions you put on the module name: `echo 'BEGIN {qx {rm -rf /}}' > MyModule.pm` [download] and then you hand 'MyModule.pm' to the program. If the program is not running on behalf of someone else (like, uhm, 99% of the programs outthere), there's no security issue with string eval anyway.	[reply] [d/l]
Re^7: Use with variable by Corion (Patriarch) on Sep 08, 2004 at 14:47 UTC


Keep It Simple, Stupid
	PerlMonks