.TH FAUTH 2
.SH NAME
fauth \- set up authentication on a file descriptor to a file server
.SH SYNOPSIS
.nf
.PP
.ft L
#include <u.h>
#include <libc.h>
.PP
.ft P
.B
int   fauth(int fd, char *aname)
.SH DESCRIPTION
.PP
.I Fauth
is used to establish authentication for the current user to access
the resources available through the 9P connection represented by
.IR fd .
The return value is a file descriptor, conventionally called
.BR afd ,
that is subsequently used to negotiate the authentication protocol
for the server, typically using
.IR auth_proxy
or
.IR fauth_proxy
(see
.IR auth (2)).
After successful authentication,
.B afd
may be passed as the second argument to a subsequent
.B mount
call (see
.IR bind (2)),
with the same
.IR aname,
as a ticket-of-entry for the user.
.PP
If
.I fauth
returns -1, the error case, that means the file server does not require
authentication for the connection, and
.B afd
should be set to -1
in the call to
.BR mount.
.PP
It is rare to use
.IR fauth
directly; more commonly
.I amount
(see
.IR auth (2))
is used.
.SH SOURCE
.B /sys/src/libc/9syscall
.SH SEE ALSO
.IR attach (5),
.IR auth (2)
(particularly
.BR amount ),
.IR authsrv (6),
.IR auth (8)
.SH DIAGNOSTICS
Sets
.IR errstr .