RE: "Require" in a sandboxed environment

["Tom Miles" <Tom@...>]

Lol.  You're on exactly the same train of thought that I had.  If you
see my original post, you will see that to try and get around that I
wrote this function:

function Require(pack)
        require(pack)
        local t = {}
        local mt = { __index = function(t,k) return
package.loaded[pack][k] end }
        setmetatable(t, mt)
        return t
End

Therefore whenever I wanted to require a package, I did:

utils = Require("utils") 

This would then always directly reference the table package.loaded.utils

However, this didn't work as I expected in some cases.  The only reason
that I could think of is that each state had their own version of
package, which is why I sent my original email, just to verify that I
wasn't going mad.  (Which I may well be)

-----Original Message-----
From: lua-bounces@bazar2.conectiva.com.br
[mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of Nick Gammon
Sent: 09 August 2007 23:21
To: Lua list
Subject: Re: "Require" in a sandboxed environment


On 02/08/2007, at 5:48 PM, Tom Miles wrote:

> code from environment 1:
>
> utils = require "Utilities"
>
> utils.g_var = 1
> print(utils.g_var)
>
> -----------------------------------------------------
>
> code from environment 2:
>
> utils = require "Utilities"
>
> print(utils.g_var)

> In the lua code example given, env 1 and env 2 would both inherit a 
> common host environment, which itself is a child of the main state.
> i.e.
>
> main->host->env 1
>                      ->env 2


OK, here is another guess. :)

env1 and env2 both have their own states with a metatable entry for
__index for Lua globals. However under that setup "utils" is a local
variable to both env1 and env2. That is, they both have their own
"utils" variable. Thus you are not sharing "utils", and an attempt to
print(utils.g_var) will not reference the other "utils".

What *may* work is to do this at the global state (that is, not in a
sub-environment):

utils = require "Utilities"

This establishes utils at global scope.

- Nick
 








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