openfd – prepare a fid for I/O using a file descriptor|
size Topenfd tag fid mode|
size Ropenfd tag qid iounit unixfd
The openfd request behaves like open, except that it prepares
and returns a Unix file descriptor corresponding to the opened
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.|
Fsopenfd (see 9pclient(3)) generates an openfd message.|