Example #1
0
File: udev.go Project: jessta/udev
func (m Monitor) Fd() error {
	err := C.udev_monitor_get_fd(m.ptr)
	if err == 0 {
		return nil
	}
	return Error(err)
}
Example #2
0
func MonitorUdev(subsystem string) (*Monitor, error) {
	cName := C.CString("udev")
	defer C.free(unsafe.Pointer(cName))

	udev := C.udev_new()
	udev_monitor := C.udev_monitor_new_from_netlink(udev, cName)

	if udev_monitor == nil {
		C.udev_unref(udev)
		return nil, Error{"udev_monitor_new_from_netlink"}
	}

	if subsystem != "" {
		cSubsystem := C.CString(subsystem)
		defer C.free(unsafe.Pointer(cSubsystem))

		if C.udev_monitor_filter_add_match_subsystem_devtype(udev_monitor, cSubsystem, nil) < 0 {
			C.udev_monitor_unref(udev_monitor)
			C.udev_unref(udev)
			return nil, Error{"udev_monitor_filter_add_match_subsystem_devtype"}
		}
	}

	if C.udev_monitor_enable_receiving(udev_monitor) < 0 {
		C.udev_monitor_unref(udev_monitor)
		C.udev_unref(udev)
		return nil, Error{"udev_monitor_enable_receiving"}
	}

	// set blocking
	if fd := C.udev_monitor_get_fd(udev_monitor); fd < 0 {
		C.udev_monitor_unref(udev_monitor)
		C.udev_unref(udev)
		return nil, Error{"udev_monitor_get_fd"}
	} else if err := syscall.SetNonblock(int(fd), false); err != nil {
		C.udev_monitor_unref(udev_monitor)
		C.udev_unref(udev)
		return nil, err
	}

	return &Monitor{udev, udev_monitor}, nil
}
Example #3
0
// DeviceChan binds the udev_monitor socket to the event source and spawns a
// goroutine. The goroutine efficiently waits on the monitor socket using epoll.
// Data is received from the udev monitor socket and a new Device is created
// with the data received. Pointers to the device are sent on the returned channel.
// The function takes a done signalling channel as a parameter, which when
// triggered will stop the goroutine and close the device channel.
// Only socket connections with uid=0 are accepted.
func (m *Monitor) DeviceChan(done <-chan struct{}) (<-chan *Device, error) {

	var event unix.EpollEvent
	var events [maxEpollEvents]unix.EpollEvent

	// Lock the context
	m.lock()
	defer m.unlock()

	// Enable receiving
	if C.udev_monitor_enable_receiving(m.ptr) != 0 {
		return nil, errors.New("udev: udev_monitor_enable_receiving failed")
	}

	// Set the fd to non-blocking
	fd := C.udev_monitor_get_fd(m.ptr)
	if e := unix.SetNonblock(int(fd), true); e != nil {
		return nil, errors.New("udev: unix.SetNonblock failed")
	}

	// Create an epoll fd
	epfd, e := unix.EpollCreate1(0)
	if e != nil {
		return nil, errors.New("udev: unix.EpollCreate1 failed")
	}

	// Add the fd to the epoll fd
	event.Events = unix.EPOLLIN | unix.EPOLLET
	event.Fd = int32(fd)
	if e = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, int(fd), &event); e != nil {
		return nil, errors.New("udev: unix.EpollCtl failed")
	}

	// Create the channel
	ch := make(chan *Device)

	// Create goroutine to epoll the fd
	go func(done <-chan struct{}, fd int32) {
		// Close the epoll fd when goroutine exits
		defer unix.Close(epfd)
		// Close the channel when goroutine exits
		defer close(ch)
		// Loop forever
		for {
			// Poll the file descriptor
			nevents, e := unix.EpollWait(epfd, events[:], epollTimeout)
			if e != nil {
				return
			}
			// Process events
			for ev := 0; ev < nevents; ev++ {
				if events[ev].Fd == fd {
					if (events[ev].Events & unix.EPOLLIN) != 0 {
						for d := m.receiveDevice(); d != nil; d = m.receiveDevice() {
							ch <- d
						}
					}
				}
			}
			// Check for done signal
			select {
			case <-done:
				return
			default:
			}
		}
	}(done, int32(fd))

	return ch, nil
}