[racket] un-tarring and un-zipping files?

> The resulting zip/tar/tgz files should be unpackable by the standard
> tools.  (There is no racket code that does that, since creating a
> standard archive is easy, but parsing one runs into problems due to
> incompatibilities of these archives.)

Ok.  Is there a standard library for packaging up a directory's
contents to a bytestream, and vice-versa?  I suspect .plt is supposed
to be a partial answer to this, but it seems like overkill for what I
want.

If there's nothing out there, I'll just cook something up with
pathlist-closure and file/gzip, file/gunzip, but if someone's already
done the work, I'd like to reuse.