| .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. |