From: ts <decoux@...>
Date: 2003-08-13T00:53:30+09:00
Subject: Re: $SAFE = 5 and Safe Ruby Misleading?

>>>>> "D" == Dave Fayram <kirindave@lensmen.net> writes:

D> Basically, can I evaluate something in a $SAFE = 4 thread, then get it 
D> out and work with it meaningfully? The only way I can think of is to 
D> try analyzing it in a $SAFE = 3 thread, where an object can't untaint 
D> itself, but doing so for an object would be pretty much impossible.

 No, the only way to do it is to make the analysis at $SAFE = 4 and return
 an object with a known class.

 Never try to interpret at a lower level the result of a block evaluated at
 level 4.

 You have an example of such mechanism in plruby (but it's written in
 C). When plruby run with a timeout, it has 3 threads :
   * main thread (level 3)
   * timeout thread (level 3)
   * user thread (level 4)

 All evaluations are made in the user thread, and the user thread must
 return a valid object which is valided at level 4. The main thread never
 try to evaluate some code, it just expect a valid object.


Guy Decoux