New VMMaker/svn release

[Andreas Raab]

tim Rowledge wrote:
>> Can somebody remind what the intent of that change was? I'm sure  
>> there must've been some reason for it but I think I've missed the  
>> discussion of that feature.
> 
> We've discussed it several times on this list and others since  (believe 
> it or not, I was amazed) November. November 2001 that is...

Oh, I believe it. Coincidentally, this would also be the exact time 
frame when I moved from the US to Germany and probably wasn't paying 
close attention ;-)

> Part of my liking of the idea is reducing code duplication and the  
> concomitant likelihood of mis-duplication - think of it as a service  
> the VM core offers plugins. Why is hiding one plugin's session ID  
> useful? I can't immediately think of anything devious one could  
> usefully do with this secret info.

Actually it really isn't all that secret (which is part of the problem). 
If you were to manifacture a file handle you could inspect an existing 
one and copy the session ID out of it. The one thing it does do is 
preventing mixing up file handles with other I/O handles if they have 
the same size and different magic numbers.

> Obviously one doesn't have to use this facility but I can't see any  
> reason not to.

True. Although I think it is really valuable if a plugin can verify that 
a handle is genuine (e.g., actually produced by that plugin). See the 
following message.

Cheers,
   - Andreas