| .TH OPENFD 9P |
| .SH NAME |
| openfd \- prepare a fid for I/O using a file descriptor |
| .SH SYNOPSIS |
| .ta \w'\fLTopenfd 'u |
| .IR size [4] |
| .B Topenfd |
| .IR tag [2] |
| .IR fid [4] |
| .IR mode [1] |
| .br |
| .IR size [4] |
| .B Ropenfd |
| .IR tag [2] |
| .IR qid [13] |
| .IR iounit [4] |
| .IR unixfd [4] |
| .SH DESCRIPTION |
| The |
| .I openfd |
| request behaves like open, except that it prepares and returns |
| a Unix file descriptor corresponding to the opened fid. |
| .PP |
| After a successful |
| .I open |
| transaction, |
| .I fid |
| is considered by the client to have been clunked |
| and can be reused. |
| .PP |
| 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 |
| .I mode |
| must be |
| .B OREAD |
| or |
| .BR OWRITE ; |
| it cannot be |
| .BR ORDWR . |
| .PP |
| .I Openfd |
| is implemented by |
| .IR 9pserve (4). |
| 9P servers that post their services using |
| .IR 9pserve (4) |
| (or indirectly via |
| .IR post9pservice (3)) |
| will never see a |
| .B Topenfd |
| message. |
| .SH ENTRY POINTS |
| .I Fsopenfd |
| (see |
| .IR 9pclient (3)) |
| generates an |
| .B openfd |
| message. |
