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.TH FVERSION 2

.SH NAME

fversion \- initialize 9P connection and negotiate version

.SH SYNOPSIS

.nf

.PP

.ft L

#include <u.h>

#include <libc.h>

.PP

.ft P

.B

int   fversion(int fd, int bufsize, char *version, int nversion)

.SH DESCRIPTION

.PP

.I Fversion

is used to initialize the 9P connection represented by

.I fd

and to negotiate the version of the protocol to be used.

.PP

The

.I bufsize

determines the size of the I/O buffer used to stage 9P requests to the server,

subject to the constraints of the server itself.

The

.I version

is a text string that represents the highest version level the protocol will support.

The

.I version

will be overwritten with the negotiated, possibly lower, version of the protocol.

The return value of

.I fversion

is the length of the returned version string; the value of

.I nversion

is therefore not the length of the version string presented to the system call,

but the total length of the buffer to accept the final result, in the manner of a read system call.

.PP

Default values of zero for

.I bufsize

and the empty string for

.I version

will negotiate sensible defaults for the connection.

If

.I version

is the empty string,

.I nversion

must still be large enough to receive the returned version string.

.PP

The interpretation of the version strings is defined in

.IR version (5).

.PP

It is rare to use

.IR fversion

directly; usually the default negotiation performed

by the kernel during

.B mount

(see

.IR bind (2))

or even more commonly

.B amount

(see

.IR auth (2))

is sufficient.

.SH SOURCE

.B /sys/src/libc/9syscall

.SH SEE ALSO

.IR intro (5),

.IR version (5),

.IR fauth (2).

.SH DIAGNOSTICS

Sets

.IR errstr .