In the one native module that I have written, integration of GSSAPI, I end up passing large byte buffers back and forth between Elisp and C. There really is no efficient way to do this, so I ended up having to use vectors and use extract_integer in a loop.

Am I misunderstanding this discussion, and there is a better way to pass binary buffers to modules that I don't know about?

This is what the current code looks like, and it's not really pretty: https://github.com/lokedhs/emacs-gssapi/blob/master/gssapi.c#L382

Regards,

Elias