//sys	socket(domain int, typ int, proto int) (fd int, err error) = libsocket.__xnet_socket
//sysnb	socketpair(domain int, typ int, proto int, fd *[2]int32) (err error) = libsocket.__xnet_socketpair
//sys	write(fd int, p []byte) (n int, err error)
//sys	writev(fd int, iovecs []Iovec) (n uintptr, err error)