brightness: add udev monitor, bind OSDs to netlink events

fixes #863

core/internal/server/brightness/manager.go

@@ -54,6 +54,7 @@ func (m *Manager) initSysfs() {
 		m.sysfsBackend = sysfs
 		m.sysfsReady = true
 		m.updateState()
+		m.initUdev()
 		return
 	}
 
@@ -65,6 +66,11 @@ func (m *Manager) initSysfs() {
 	m.sysfsBackend = sysfs
 	m.sysfsReady = true
 	m.updateState()
+	m.initUdev()
+}
+
+func (m *Manager) initUdev() {
+	m.udevMonitor = NewUdevMonitor(m)
 }
 
 func (m *Manager) initDDC() {

core/internal/server/brightness/types.go

@@ -43,6 +43,7 @@ type Manager struct {
 	logindBackend *LogindBackend
 	sysfsBackend  *SysfsBackend
 	ddcBackend    *DDCBackend
+	udevMonitor   *UdevMonitor
 
 	logindReady bool
 	sysfsReady  bool
@@ -181,6 +182,10 @@ func (m *Manager) Close() {
 		return true
 	})
 
+	if m.udevMonitor != nil {
+		m.udevMonitor.Close()
+	}
+
 	if m.logindBackend != nil {
 		m.logindBackend.Close()
 	}

core/internal/server/brightness/udev.go

@@ -0,0 +1,148 @@
+package brightness
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/AvengeMedia/DankMaterialShell/core/internal/log"
+	"github.com/pilebones/go-udev/netlink"
+)
+
+type UdevMonitor struct {
+	stop chan struct{}
+}
+
+func NewUdevMonitor(manager *Manager) *UdevMonitor {
+	m := &UdevMonitor{
+		stop: make(chan struct{}),
+	}
+
+	go m.run(manager)
+	return m
+}
+
+func (m *UdevMonitor) run(manager *Manager) {
+	conn := &netlink.UEventConn{}
+	if err := conn.Connect(netlink.UdevEvent); err != nil {
+		log.Errorf("Failed to connect to udev netlink: %v", err)
+		return
+	}
+	defer conn.Close()
+
+	matcher := &netlink.RuleDefinitions{
+		Rules: []netlink.RuleDefinition{
+			{Env: map[string]string{"SUBSYSTEM": "backlight"}},
+			{Env: map[string]string{"SUBSYSTEM": "leds"}},
+		},
+	}
+	if err := matcher.Compile(); err != nil {
+		log.Errorf("Failed to compile udev matcher: %v", err)
+		return
+	}
+
+	events := make(chan netlink.UEvent)
+	errs := make(chan error)
+	conn.Monitor(events, errs, matcher)
+
+	log.Info("Udev monitor started for backlight/leds events")
+
+	for {
+		select {
+		case <-m.stop:
+			return
+		case err := <-errs:
+			log.Errorf("Udev monitor error: %v", err)
+			return
+		case event := <-events:
+			m.handleEvent(manager, event)
+		}
+	}
+}
+
+func (m *UdevMonitor) handleEvent(manager *Manager, event netlink.UEvent) {
+	subsystem := event.Env["SUBSYSTEM"]
+	devpath := event.Env["DEVPATH"]
+
+	if subsystem == "" || devpath == "" {
+		return
+	}
+
+	sysname := filepath.Base(devpath)
+	action := string(event.Action)
+
+	switch action {
+	case "change":
+		m.handleChange(manager, subsystem, sysname)
+	case "add", "remove":
+		log.Debugf("Udev %s event: %s:%s - triggering rescan", action, subsystem, sysname)
+		manager.Rescan()
+	}
+}
+
+func (m *UdevMonitor) handleChange(manager *Manager, subsystem, sysname string) {
+	deviceID := subsystem + ":" + sysname
+
+	if manager.sysfsBackend == nil {
+		return
+	}
+
+	brightnessPath := filepath.Join(manager.sysfsBackend.basePath, subsystem, sysname, "brightness")
+	data, err := os.ReadFile(brightnessPath)
+	if err != nil {
+		log.Debugf("Udev change event for %s but failed to read brightness: %v", deviceID, err)
+		return
+	}
+
+	brightness, err := strconv.Atoi(strings.TrimSpace(string(data)))
+	if err != nil {
+		log.Debugf("Failed to parse brightness for %s: %v", deviceID, err)
+		return
+	}
+
+	manager.handleUdevBrightnessChange(deviceID, brightness)
+}
+
+func (m *UdevMonitor) Close() {
+	close(m.stop)
+}
+
+func (m *Manager) handleUdevBrightnessChange(deviceID string, rawBrightness int) {
+	if m.sysfsBackend == nil {
+		return
+	}
+
+	dev, err := m.sysfsBackend.GetDevice(deviceID)
+	if err != nil {
+		log.Debugf("Udev event for unknown device %s: %v", deviceID, err)
+		return
+	}
+
+	percent := m.sysfsBackend.ValueToPercent(rawBrightness, dev, false)
+
+	m.stateMutex.Lock()
+	var found bool
+	for i, d := range m.state.Devices {
+		if d.ID != deviceID {
+			continue
+		}
+		found = true
+		if d.Current == rawBrightness {
+			m.stateMutex.Unlock()
+			return
+		}
+		m.state.Devices[i].Current = rawBrightness
+		m.state.Devices[i].CurrentPercent = percent
+		break
+	}
+	m.stateMutex.Unlock()
+
+	if !found {
+		log.Debugf("Udev event for device not in state: %s", deviceID)
+		return
+	}
+
+	log.Debugf("Udev brightness change: %s -> %d (%d%%)", deviceID, rawBrightness, percent)
+	m.broadcastDeviceUpdate(deviceID)
+}

core/internal/server/brightness/udev_test.go

@@ -0,0 +1,260 @@
+package brightness
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/pilebones/go-udev/netlink"
+)
+
+func setupTestManager(t *testing.T) (*Manager, string) {
+	tmpDir := t.TempDir()
+
+	backlightDir := filepath.Join(tmpDir, "backlight", "intel_backlight")
+	if err := os.MkdirAll(backlightDir, 0755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(backlightDir, "max_brightness"), []byte("1000\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(backlightDir, "brightness"), []byte("500\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	sysfs := &SysfsBackend{
+		basePath: tmpDir,
+		classes:  []string{"backlight"},
+	}
+	if err := sysfs.scanDevices(); err != nil {
+		t.Fatal(err)
+	}
+
+	m := &Manager{
+		sysfsBackend: sysfs,
+		sysfsReady:   true,
+		stopChan:     make(chan struct{}),
+	}
+
+	m.state = State{
+		Devices: []Device{
+			{
+				Class:          ClassBacklight,
+				ID:             "backlight:intel_backlight",
+				Name:           "intel_backlight",
+				Current:        500,
+				Max:            1000,
+				CurrentPercent: 50,
+				Backend:        "sysfs",
+			},
+		},
+	}
+
+	return m, tmpDir
+}
+
+func TestHandleUdevBrightnessChange_UpdatesState(t *testing.T) {
+	m, _ := setupTestManager(t)
+
+	m.handleUdevBrightnessChange("backlight:intel_backlight", 750)
+
+	state := m.GetState()
+	if len(state.Devices) != 1 {
+		t.Fatalf("expected 1 device, got %d", len(state.Devices))
+	}
+
+	dev := state.Devices[0]
+	if dev.Current != 750 {
+		t.Errorf("expected Current=750, got %d", dev.Current)
+	}
+	if dev.CurrentPercent != 75 {
+		t.Errorf("expected CurrentPercent=75, got %d", dev.CurrentPercent)
+	}
+}
+
+func TestHandleUdevBrightnessChange_NoChangeWhenSameValue(t *testing.T) {
+	m, _ := setupTestManager(t)
+
+	updateCh := m.SubscribeUpdates("test")
+	defer m.UnsubscribeUpdates("test")
+
+	m.handleUdevBrightnessChange("backlight:intel_backlight", 500)
+
+	select {
+	case <-updateCh:
+		t.Error("should not broadcast when brightness unchanged")
+	case <-time.After(50 * time.Millisecond):
+	}
+}
+
+func TestHandleUdevBrightnessChange_BroadcastsOnChange(t *testing.T) {
+	m, _ := setupTestManager(t)
+
+	updateCh := m.SubscribeUpdates("test")
+	defer m.UnsubscribeUpdates("test")
+
+	m.handleUdevBrightnessChange("backlight:intel_backlight", 750)
+
+	select {
+	case update := <-updateCh:
+		if update.Device.Current != 750 {
+			t.Errorf("broadcast had wrong Current: got %d, want 750", update.Device.Current)
+		}
+	case <-time.After(100 * time.Millisecond):
+		t.Error("expected broadcast on brightness change")
+	}
+}
+
+func TestHandleUdevBrightnessChange_UnknownDevice(t *testing.T) {
+	m, _ := setupTestManager(t)
+
+	m.handleUdevBrightnessChange("backlight:unknown_device", 500)
+
+	state := m.GetState()
+	if len(state.Devices) != 1 {
+		t.Errorf("state should be unchanged, got %d devices", len(state.Devices))
+	}
+}
+
+func TestHandleUdevBrightnessChange_NilSysfsBackend(t *testing.T) {
+	m := &Manager{
+		sysfsBackend: nil,
+		stopChan:     make(chan struct{}),
+	}
+
+	m.handleUdevBrightnessChange("backlight:test", 500)
+}
+
+func TestHandleUdevBrightnessChange_DeviceNotInState(t *testing.T) {
+	m, _ := setupTestManager(t)
+
+	m.sysfsBackend.deviceCache.Store("backlight:other_device", &sysfsDevice{
+		class:         ClassBacklight,
+		id:            "backlight:other_device",
+		name:          "other_device",
+		maxBrightness: 100,
+		minValue:      1,
+	})
+
+	m.handleUdevBrightnessChange("backlight:other_device", 50)
+
+	state := m.GetState()
+	for _, d := range state.Devices {
+		if d.ID == "backlight:other_device" {
+			t.Error("device should not be added to state via udev change event")
+		}
+	}
+}
+
+func TestHandleEvent_ChangeAction(t *testing.T) {
+	m, tmpDir := setupTestManager(t)
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	brightnessPath := filepath.Join(tmpDir, "backlight", "intel_backlight", "brightness")
+	if err := os.WriteFile(brightnessPath, []byte("800\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	event := netlink.UEvent{
+		Action: netlink.CHANGE,
+		Env: map[string]string{
+			"SUBSYSTEM": "backlight",
+			"DEVPATH":   "/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight",
+		},
+	}
+
+	um.handleEvent(m, event)
+
+	state := m.GetState()
+	if state.Devices[0].Current != 800 {
+		t.Errorf("expected Current=800 after change event, got %d", state.Devices[0].Current)
+	}
+}
+
+func TestHandleEvent_MissingEnvVars(t *testing.T) {
+	m, _ := setupTestManager(t)
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	event := netlink.UEvent{
+		Action: netlink.CHANGE,
+		Env:    map[string]string{},
+	}
+
+	um.handleEvent(m, event)
+
+	state := m.GetState()
+	if state.Devices[0].Current != 500 {
+		t.Error("state should be unchanged with missing env vars")
+	}
+}
+
+func TestHandleEvent_MissingSubsystem(t *testing.T) {
+	m, _ := setupTestManager(t)
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	event := netlink.UEvent{
+		Action: netlink.CHANGE,
+		Env: map[string]string{
+			"DEVPATH": "/devices/foo/bar",
+		},
+	}
+
+	um.handleEvent(m, event)
+
+	state := m.GetState()
+	if state.Devices[0].Current != 500 {
+		t.Error("state should be unchanged with missing SUBSYSTEM")
+	}
+}
+
+func TestHandleChange_BrightnessFileNotFound(t *testing.T) {
+	m, _ := setupTestManager(t)
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	um.handleChange(m, "backlight", "nonexistent_device")
+
+	state := m.GetState()
+	if state.Devices[0].Current != 500 {
+		t.Error("state should be unchanged when brightness file not found")
+	}
+}
+
+func TestHandleChange_InvalidBrightnessValue(t *testing.T) {
+	m, tmpDir := setupTestManager(t)
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	brightnessPath := filepath.Join(tmpDir, "backlight", "intel_backlight", "brightness")
+	if err := os.WriteFile(brightnessPath, []byte("not_a_number\n"), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	um.handleChange(m, "backlight", "intel_backlight")
+
+	state := m.GetState()
+	if state.Devices[0].Current != 500 {
+		t.Error("state should be unchanged with invalid brightness value")
+	}
+}
+
+func TestUdevMonitor_Close(t *testing.T) {
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	um.Close()
+
+	select {
+	case <-um.stop:
+	default:
+		t.Error("stop channel should be closed")
+	}
+}
+
+func TestHandleChange_NilSysfsBackend(t *testing.T) {
+	m := &Manager{
+		sysfsBackend: nil,
+		stopChan:     make(chan struct{}),
+	}
+	um := &UdevMonitor{stop: make(chan struct{})}
+
+	um.handleChange(m, "backlight", "test_device")
+}