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.\"	@(#)nfssvc.2	8.1 (Berkeley) 6/9/93
.\"
.Dd January 9, 2007
.Dt NFSSVC 2
.Os
.Sh NAME
.Nm nfssvc
.Nd NFS services
.Sh SYNOPSIS
.Fd #include <unistd.h>
.Fd #include <nfs/nfs.h>
.Ft int
.Fn nfssvc "int flags" "void *argstructp"
.Sh DESCRIPTION
The
.Fn nfssvc
function is used by the NFS server daemon to pass information into and out
of the kernel and also to enter the kernel as a server daemon.
The
.Fa flags
argument consists of several bits that show what action is to be taken
once in the kernel and the
.Fa argstructp
points to any corresponding data that the action may require.
.Pp
.Fn nfssvc
is called with the flag
.Dv NFSSVC_NFSD
and a NULL
.Fa argstructp
to enter the kernel as an
.Xr nfsd 8
daemon.  The
.Dv NFSSVC_NFSD
action normally does not return until the NFS server is stopped.
.Pp
The
.Xr nfsd 8
server daemon calls
.Fn nfssvc
with the flag
.Dv NFSSVC_ADDSOCK
and a pointer to a
.Bd -literal
struct nfsd_args {
	int	sock;		/* Socket to serve */
	caddr_t	name;		/* Client address for connection based sockets */
	int	namelen;	/* Length of name */
};
.Ed
.sp
to pass a server side
.Tn NFS
socket into the kernel for servicing by the
.Xr nfsd 8
daemons.
.Pp
The
.Xr nfsd 8
server daemon calls
.Fn nfssvc
with the flag
.Dv NFSSVC_EXPORT
and a pointer to a
.Bd -literal
struct nfs_export_args {
	uint32_t		nxa_fsid;	/* export FS ID */
	uint32_t		nxa_expid;	/* export ID */
	char			*nxa_fspath;	/* export FS path */
	char			*nxa_exppath;	/* export sub-path */
	uint32_t		nxa_flags;	/* export arg flags */
	uint32_t		nxa_netcount;	/* #entries in ex_nets array */
	struct nfs_export_net_args *nxa_nets;	/* array of net args */
};
.Ed
.sp
to pass exported file system information into the kernel.
.Sh RETURN VALUES
Upon successful completion, a value of 0 is returned.  Otherwise, -1 is
returned the global variable
.Va errno
is set to specify the error.
.Pp
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
The caller is not the super-user.
.It Bq Er EINVAL
The action specified by the
.Fa flags
argument was not valid.
.It Bq EFAULT
.Fa argstructp
points to an invalid address.
.It Bq ENOMEM
A memory allocation failure prevented the action from completing.
.It Bq EEXIST
An attempt was made to add a UDP socket via the
.Dv NFSSVC_ADDSOCK
action, but the UDP socket has already been added.
.El
.Sh SEE ALSO
.Xr nfsd 8
.Sh HISTORY
The
.Nm nfssvc
function first appeared in 4.4BSD.
.Sh BUGS
The
.Nm nfssvc
system call is designed specifically for the
.Tn NFS
server daemons and as such is specific to their requirements.  Several
fields of the argument structures are assumed to be valid, such that
.Nm nfssvc
must be used with extreme care.