FVERSION(2) FVERSION(2)
NAME
fversion - initialize 9P connection and negotiate version
SYNOPSIS
#include <u.h>
#include <libc.h>
int fversion(int fd, int bufsize, char *version, int nversion)
DESCRIPTION
Fversion is used to initialize the 9P connection represented
by fd and to negotiate the version of the protocol to be
used.
The 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 version is a text string that
represents the highest version level the protocol will sup-
port. The version will be overwritten with the negotiated,
possibly lower, version of the protocol. The return value
of fversion is the length of the returned version string;
the value of 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 man-
ner of a read system call.
Default values of zero for bufsize and the empty string for
version will negotiate sensible defaults for the connection.
If version is the empty string, nversion must still be large
enough to receive the returned version string.
The interpretation of the version strings is defined in
version(5).
It is rare to use fversion directly; usually the default
negotiation performed by the kernel during mount (see
bind(2)) or even more commonly amount (see auth(2)) is suf-
ficient.
SOURCE
/sys/src/libc/9syscall
SEE ALSO
intro(5), version(5), fauth(2).
DIAGNOSTICS
Sets errstr.
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