Tclunk closes a fid for I/O and disassociates it from any file. Regardless of the success or failure of a Tclunk request, once it is sent, the fid is no longer considered to be associated with the file, and can be re-used in another Twalk or Tattach request.
of_iovec verifies a message from an I/O vector. No copying is done, and of_iovec only performs bounds checks. Modifying the underlying I/O vector will change the results when accessing message fields.