Function zxio_getsockopt 

pub unsafe extern "C" fn zxio_getsockopt(
    io: *mut zxio_t,
    level: c_int,
    optname: c_int,
    optval: *mut c_void,
    optlen: *mut socklen_t,
    out_code: *mut i16,
) -> zx_status_t