// return zero oob bytes
			t.Fatalf("ReadMsgUnix oobn = %d, want %d", oobn2, oobn)
		}
		oob2 = oob2[:oobn2]
		if !bytes.Equal(oob, oob2) {
			t.Fatal("ReadMsgUnix oob bytes don't match")
		}

		scm, err := syscall.ParseSocketControlMessage(oob2)
		if err != nil {
			t.Fatalf("ParseSocketControlMessage: %v", err)
		}
		newUcred, err := syscall.ParseUnixCredentials(&scm[0])

}

func (fd *netFD) writeMsg(p []byte, oob []byte, sa syscall.Sockaddr) (n int, oobn int, err error) {
	n, oobn, err = fd.pfd.WriteMsg(p, oob, sa)
	runtime.KeepAlive(fd)
	return n, oobn, wrapSyscallError(writeMsgSyscallName, err)
}

func (fd *netFD) writeMsgInet4(p []byte, oob []byte, sa *syscall.SockaddrInet4) (n int, oobn int, err error) {
	n, oobn, err = fd.pfd.WriteMsgInet4(p, oob, sa)
	runtime.KeepAlive(fd)

	return 0, nil, syscall.EPLAN9
}

func (c *IPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
	return 0, 0, 0, nil, syscall.EPLAN9
}

func (c *IPConn) writeTo(b []byte, addr *IPAddr) (int, error) {
	return 0, syscall.EPLAN9
}

func (c *IPConn) writeMsg(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
	return 0, 0, syscall.EPLAN9
}

	return 0, nil, syscall.EPLAN9
}

func (c *UnixConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
	return 0, 0, 0, nil, syscall.EPLAN9
}

func (c *UnixConn) writeTo(b []byte, addr *UnixAddr) (int, error) {
	return 0, syscall.EPLAN9
}

func (c *UnixConn) writeMsg(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
	return 0, 0, syscall.EPLAN9
}

	return syscall.ENOSYS
}

func SendmsgNInet4(fd int, p, oob []byte, to *syscall.SockaddrInet4, flags int) (n int, err error) {
	return 0, syscall.ENOSYS
}

func SendmsgNInet6(fd int, p, oob []byte, to *syscall.SockaddrInet6, flags int) (n int, err error) {
	return 0, syscall.ENOSYS
}

func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error) {
	return 0, 0, 0, syscall.ENOSYS

//go:noescape
func SendmsgNInet4(fd int, p, oob []byte, to *syscall.SockaddrInet4, flags int) (n int, err error)

//go:linkname SendmsgNInet6 syscall.sendmsgNInet6
//go:noescape
func SendmsgNInet6(fd int, p, oob []byte, to *syscall.SockaddrInet6, flags int) (n int, err error)

//go:linkname RecvmsgInet4 syscall.recvmsgInet4
//go:noescape

	return syscall.ENOSYS
}

func SendmsgNInet4(fd int, p, oob []byte, to *syscall.SockaddrInet4, flags int) (n int, err error) {
	return 0, syscall.ENOSYS
}

func SendmsgNInet6(fd int, p, oob []byte, to *syscall.SockaddrInet6, flags int) (n int, err error) {
	return 0, syscall.ENOSYS
}

func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error) {
	return 0, 0, 0, syscall.ENOSYS

	if 20 > l || l > len(b) {
		return n
	}
	if b[0]>>4 != 4 {
		return n
	}
	copy(b, b[l:])
	return n - l
}

func (c *IPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
	var sa syscall.Sockaddr
	n, oobn, flags, sa, err = c.fd.readMsg(b, oob, 0)
	switch sa := sa.(type) {
	case *syscall.SockaddrInet4:
		addr = &IPAddr{IP: sa.Addr[0:]}
	case *syscall.SockaddrInet6:

	err = ucr.SetReadDeadline(time.Now().Add(5 * time.Second))
	if err != nil {
		t.Fatalf("Can't set unix connection timeout: %v", err)
	}
	_, oobn, _, _, err := ucr.ReadMsgUnix(nil, oob)
	if err != nil {
		t.Fatalf("UnixConn readMsg: %v", err)
	}

	scms, err := syscall.ParseSocketControlMessage(oob[:oobn])
	if err != nil {
		t.Fatalf("ParseSocketControlMessage: %v", err)
	}
	if len(scms) != 1 {

		}
	}
	return n, addr, err
}

func (c *UnixConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
	var sa syscall.Sockaddr
	n, oobn, flags, sa, err = c.fd.readMsg(b, oob, readMsgFlags)
	if readMsgFlags == 0 && err == nil && oobn > 0 {
		setReadMsgCloseOnExec(oob[:oobn])
	}

	switch sa := sa.(type) {
	case *syscall.SockaddrUnix:
		if sa.Name != "" {