nc 0.9.8

Access system calls directly
Documentation 
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/// Attempts to cancel an iocb previously passed to `io_submit`.
///
/// If the operation is successfully cancelled, the resulting event is
/// copied into the memory pointed to by `result` without being placed
/// into the completion queue and 0 is returned.
///
///
/// # Errors
/// - May fail with `-EFAULT` if any of the data structures pointed to are invalid.
/// - May fail with `-EINVAL` if `aio_context` specified by `ctx_id` is invalid.
/// - May fail with `-EAGAIN` if the iocb specified was not cancelled.
/// - Will fail with `-ENOSYS` if not implemented.
pub unsafe fn io_cancel(
    ctx_id: aio_context_t,
    iocb: &iocb_t,
    result: &mut io_event_t,
) -> Result<(), Errno> {
    let iocb_ptr = core::ptr::from_ref(iocb) as usize;
    let result_ptr = core::ptr::from_mut(result) as usize;
    unsafe { syscall3(SYS_IO_CANCEL, ctx_id, iocb_ptr, result_ptr).map(drop) }
}