OPENFD(9P)                                             OPENFD(9P)

     NAME
          openfd - prepare a fid for I/O using a file descriptor

     SYNOPSIS
          size[4] Topenfd tag[2] fid[4] mode[1]
          size[4] Ropenfd tag[2] qid[13] iounit[4] unixfd[4]

     DESCRIPTION
          The openfd request behaves like open, except that it pre-
          pares and returns a Unix file descriptor corresponding to
          the opened fid.

          After a successful open transaction, fid is considered by
          the client to have been clunked and can be reused.

          The returned Unix file descriptor is one end of a Unix pipe.
          A proxy process at the other end transfers data between the
          pipe and the 9P server.  Because it is a pipe, errors on
          reads and writes are discarded and mode must be OREAD or
          OWRITE; it cannot be ORDWR.

          Openfd is implemented by 9pserve(4). 9P servers that post
          their services using 9pserve(4) (or indirectly via
          post9pservice(3)) will never see a Topenfd message.

     ENTRY POINTS
          Fsopenfd (see 9pclient(3)) generates an openfd message.

     Page 1                       Plan 9             (printed 4/20/26)