.\"	$OpenBSD: nfssvc.2,v 1.20 2007/05/31 19:19:33 jmc Exp $
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.\"	@(#)nfssvc.2	8.1 (Berkeley) 6/9/93
.\"
.Dd $Mdocdate: May 31 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 NFS daemons to pass information into 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 one of two structures depending on which bits are set in
flags.
.Pp
To enter an
.Xr nfsd 8
daemon into the kernel,
.Fn nfssvc
is called with the flag
.Dv NFSSVC_NFSD
and a pointer to a structure:
.Bd -literal
struct nfsd_srvargs {
        struct nfsd     *nsd_nfsd;   /* Pointer to in kernel nfsd struct */
        uid_t           nsd_uid;        /* Effective uid mapped to cred */
        u_int32_t       nsd_haddr;      /* IP address of client */
        struct ucred    nsd_cr;         /* Cred. uid maps to */
        int             nsd_authlen;    /* Length of auth string (ret) */
        u_char          *nsd_authstr;   /* Auth string (ret) */
        int             nsd_verflen;    /* and the verifier */
        u_char          *nsd_verfstr;
        struct timeval  nsd_timestamp;  /* timestamp from verifier */
        u_int32_t       nsd_ttl;        /* credential ttl (sec) */
        NFSKERBKEY_T    nsd_key;        /* Session key */
};
.Ed
.Pp
To add further sockets for processing by the
.Xr nfsd 8
server daemons the master
.Xr nfsd 8
daemon  calls
.Fn nfssvc
with the flag
.Dv NFSSVC_ADDSOCK
and a pointer to a structure:
.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
.Sh RETURN VALUES
Normally
.Nm nfssvc
does not return unless the server
is terminated by a signal when a value of 0 is returned.
Otherwise, \-1 is returned and the global variable
.Va errno
is set to specify the error.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EPERM
The caller is not the superuser.
.It Bq Er EINVAL
The flag argument consisted of incompatible or otherwise
unsupported bits.
.El
.Sh SEE ALSO
.Xr mount_nfs 8 ,
.Xr nfsd 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm nfssvc
function first appeared in
.Bx 4.4 .
.Sh BUGS
The
.Nm nfssvc
system call is designed specifically for the
.Tn NFS
support daemons and as such is specific to their requirements.
Several fields of the argument structures are assumed to be valid and
sometimes to be unchanged from a previous call, such that
.Fn nfssvc
must be used with extreme care.