I have an editor application that I've writen that needs to read and
write XML files to disk.  I'd like to extend this program by allowing
users to extend my editor by plugging in custom code they compile using
certain interfaces.  My editor will call their code to gain use of
their functions.

However, this plugin code is untrusted, and I don't want it to access
the filesystem or network.  Is there some way I can create a sandbox
within my program in which I can run this custom code and be sure that
it cannot do things like write to the filesystem?  Perhaps create a
separate thread with special restricted permissions?

Mark McKay