/// Send a message on a socket.
pub unsafe fn send(sockfd: i32, buf: &[u8], len: size_t, flags: i32) -> Result<ssize_t, Errno> {
let sockfd = sockfd as usize;
let buf_ptr = buf.as_ptr() as usize;
let len = len as usize;
let flags = flags as usize;
syscall4(SYS_SEND, sockfd, buf_ptr, len, flags).map(|ret| ret as ssize_t)
}