Function select

#[no_mangle]
pub unsafe extern "C" fn select(
    nfds: c_int,
    readfds: *mut fd_set,
    writefds: *mut fd_set,
    exceptfds: *mut fd_set,
    timeout: *mut timeval,
) -> c_int

Monitor multiple file descriptors, waiting until one or more of the file descriptors become “ready” for some class of I/O operation