Provide recv_msg and send_msg

[Chris00]

Lwt_bytes provides recv_msg and send_msg that take a list of Cstruct.t—called io_vector there. I think that these calls should also be provided by ocaml-cstruct.

[cfcs]

I think this should be out of scope of Cstruct. Your libc bindings (on Unix, where send_msg and recv_msg are useful) should be able to work on bigarrays, in which case you can access the underlying buffer directly.

EDIT: In any case the recv_msg and send_msg are a bit crap since they do not handle writes/receives of more than 2GB, unlike the Linux sendmsg/recvmsg syscalls which return a ssize_t, ie a signed long (on 64-bit platforms that's a signed 64-bit integer).

[avsm]

It is still useful to provide the Cstruct equivalents of Lwt calls, just to avoid the possible conversion errors from dealing with offsets and so on.

[hcarty]

It could live in a separate lwt-cstruct library or sublibrary within cstruct. It would be nice in general to have cstruct IO available in Let.

[avsm]

There already is an Lwt_cstruct sublibrary :-)

[hcarty]

I should read more carefully before commenting! Sorry for the noise!

[avsm]

Not at all; thanks for paying attention to the repository at all :-)