func (m Monitor) AddFilter(subsystem string, devtype string) error {
err := C.udev_monitor_filter_add_match_subsystem_devtype(m.ptr, C.CString(subsystem), C.CString(devtype))
if err == 0 {
return nil
}
return Error(err)
}
// FilterAddMatchSubsystem adds a filter matching the device against a subsystem.
// This filter is efficiently executed inside the kernel, and libudev subscribers will usually not be woken up for devices which do not match.
// The filter must be installed before the monitor is switched to listening mode with the DeviceChan function.
func (m *Monitor) FilterAddMatchSubsystem(subsystem string) (err error) {
m.lock()
defer m.unlock()
s := C.CString(subsystem)
defer freeCharPtr(s)
if C.udev_monitor_filter_add_match_subsystem_devtype(m.ptr, s, nil) != 0 {
err = errors.New("udev: udev_monitor_filter_add_match_subsystem_devtype failed")
}
return
}
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
}
