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Diffstat (limited to 'man/man9/version.9p')
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diff --git a/man/man9/version.9p b/man/man9/version.9p new file mode 100644 index 00000000..c4961217 --- /dev/null +++ b/man/man9/version.9p @@ -0,0 +1,99 @@ +.TH VERSION 9P +.SH NAME +version \- negotiate protocol version +.SH SYNOPSIS +.ta \w'\fLTversion 'u +.IR size [4] +.B Tversion +.IR tag [2] +.IR msize [4] +.IR version [ s ] +.br +.IR size [4] +.B Rversion +.IR tag [2] +.IR msize [4] +.IR version [ s ] +.SH DESCRIPTION +The +.B version +request negotiates the protocol version and message size +to be used on the connection and initializes the connection for I/O. +.B Tversion +must be the first message sent on the 9P connection, +and the client cannot issue any further requests until it has received the +.B Rversion +reply. +The +.I tag +should be +.B NOTAG +(value +.BR (ushort)~0 ) +for a +.B version +message. +.PP +The client suggests a maximum message size, +.BR msize , +that is the maximum length, in bytes, +it will ever generate or expect to receive in a single 9P message. +This count includes all 9P protocol data, starting from the +.B size +field and extending through the message, +but excludes enveloping transport protocols. +The server responds with its own maximum, +.BR msize , +which must be less than or equal to the client's value. +Thenceforth, both sides of the connection must honor this limit. +.PP +The +.B version +string identifies the level of the protocol. +The string must always begin with the two characters +.RB `` 9P ''. +If the server does not understand the client's version string, +it should respond with an +.B Rversion +message (not +.BR Rerror ) +with the +.B version +string the 7 characters +.RB `` unknown ''. +.PP +The server may respond with the client's version string, +or a version string identifying +an earlier defined protocol version. +Currently, the only defined version is the 6 characters +.RB `` 9P2000 ''. +Version strings are defined such that, if the client string contains +one or more period characters, the initial substring up to but not including +any single period in the version string defines a version of the protocol. +After stripping any such period-separated suffix, the server is allowed to respond +with a string of the form +.BI 9P nnnn\f1, +where +.I nnnn +is less than or equal to the digits sent by the client. +.PP +The client and server will use the protocol version defined by the +server's response for all subsequent communication on the connection. +.PP +A successful +.B version +request initializes the connection. +All outstanding I/O on the connection is aborted; all active fids are freed (`clunked') automatically. +The set of messages between +.B version +requests is called a +.IR session . +.SH ENTRY POINTS +.I Fsversion +(see +.IR 9pclient (3)) +generates +.B version +messages; +it is called automatically by +.IR fsmount . |