Fauth
provides a means for the current user to authenticate to access
resources available through the Styx connection represented by
fd.
The return value is a file descriptor, conventionally called
afd,
that is subsequently used to execute the authentication protocol
for the server.
After successful authentication,
afd
may be passed as the second argument to a subsequent
mount
call (see
sys-bind(2)),
with the same
aname,
as a ticket-of-entry for the user.
If
fauth
returns nil, the error case, that means the file server does not require
authentication for the connection, and
afd
should be nil
in the call to
mount.