Fix concurrency bugs, DDC reliability, crashes, and memory leaks

Thread safety: - Fix swBrightnessSemaphore misuse causing races in software brightness - Signal semaphore before async dispatch to prevent deadlock with polling job - Wrap CGSetDisplayTransferByTable in DispatchQueue.main.sync for thread safety - Wrap shade alpha updates in DispatchQueue.main.async for AppKit safety - Move DDC probe work off main thread with configureID staleness guard - Defer gamma interference alert to next run loop iteration DDC reliability: - Only persist DDC write state after confirming hardware write succeeded - Clear stale arm64avService handles before rematching on wake/reconfig - Validate DDC/CI reply header fields before accepting read values - Cap DDC retry attempts at 30 to prevent multi-minute startup hangs - Guard against division by zero in DDC value normalization Crash fixes: - Replace force-unwrap on currentDisplay in MenuHandler - Handle gamma table acquisition failure safely - Guard against zero defaultGammaTablePeak in getSwBrightness Cleanup: - Remove shadeGrave memory leak (closed windows retained forever) - Remove dead sortDisplays() with stray Turkish comments - Remove duplicate audioSpeakerVolume DDC default assignment - Remove tautological self-comparisons in SliderHandler - Replace deprecated SMLoginItemSetEnabled with SMAppService on macOS 13+ - Replace deprecated kIOMasterPortDefault with kIOMainPortDefault on macOS 12+ - Replace direct plist read with UserDefaults.persistentDomain API
MyronKoch · May 29, 2026 · Sep 21, 2026 · Sep 21, 2026 · 85b5a652891b1919b6e1c6ecca57daf8704914fc
commit 85b5a652891b1919b6e1c6ecca57daf8704914fc
diff --git a/MonitorControl/Model/Display.swift b/MonitorControl/Model/Display.swift
@@ -162,7 +162,6 @@ class Display: Equatable {
       _ = self.setDirectBrightness(self.smoothBrightnessTransient, transient: true)
       self.smoothBrightnessRunning = false
     }
-    self.swBrightnessSemaphore.signal()
     return true
   }
 
@@ -191,7 +190,10 @@ class Display: Equatable {
     guard !self.isDummy else {
       return
     }
-    CGGetDisplayTransferByTable(self.identifier, 256, &self.defaultGammaTableRed, &self.defaultGammaTableGreen, &self.defaultGammaTableBlue, &self.defaultGammaTableSampleCount)
+    guard CGGetDisplayTransferByTable(self.identifier, 256, &self.defaultGammaTableRed, &self.defaultGammaTableGreen, &self.defaultGammaTableBlue, &self.defaultGammaTableSampleCount) == CGError.success else {
+      self.defaultGammaTablePeak = 1.0
+      return
+    }
     let redPeak = self.defaultGammaTableRed.max() ?? 0
     let greenPeak = self.defaultGammaTableGreen.max() ?? 0
     let bluePeak = self.defaultGammaTableBlue.max() ?? 0
@@ -222,23 +224,28 @@ class Display: Equatable {
     currentValue = self.swBrightnessTransform(value: currentValue)
     newValue = self.swBrightnessTransform(value: newValue)
     if smooth {
+      self.swBrightnessSemaphore.signal()
       DispatchQueue.global(qos: .userInteractive).async {
         for transientValue in stride(from: currentValue, to: newValue, by: 0.005 * (currentValue > newValue ? -1 : 1)) {
           guard app.reconfigureID == 0 else {
-            self.swBrightnessSemaphore.signal()
             return
           }
           if self.isVirtual || self.readPrefAsBool(key: .avoidGamma) {
-            _ = DisplayManager.shared.setShadeAlpha(value: 1 - transientValue, displayID: DisplayManager.resolveEffectiveDisplayID(self.identifier))
+            DispatchQueue.main.async {
+              _ = DisplayManager.shared.setShadeAlpha(value: 1 - transientValue, displayID: DisplayManager.resolveEffectiveDisplayID(self.identifier))
+            }
           } else {
             let gammaTableRed = self.defaultGammaTableRed.map { $0 * transientValue }
             let gammaTableGreen = self.defaultGammaTableGreen.map { $0 * transientValue }
             let gammaTableBlue = self.defaultGammaTableBlue.map { $0 * transientValue }
-            CGSetDisplayTransferByTable(self.identifier, self.defaultGammaTableSampleCount, gammaTableRed, gammaTableGreen, gammaTableBlue)
+            DispatchQueue.main.sync {
+              CGSetDisplayTransferByTable(self.identifier, self.defaultGammaTableSampleCount, gammaTableRed, gammaTableGreen, gammaTableBlue)
+            }
           }
           Thread.sleep(forTimeInterval: 0.001) // Let's make things quick if not performed in the background
         }
       }
+      return true
     } else {
       if self.isVirtual || self.readPrefAsBool(key: .avoidGamma) {
         self.swBrightnessSemaphore.signal()
@@ -270,6 +277,10 @@ class Display: Equatable {
       self.swBrightnessSemaphore.signal()
       return self.swBrightnessTransform(value: rawBrightnessValue, reverse: true)
     }
+    guard self.defaultGammaTablePeak != 0 else {
+      self.swBrightnessSemaphore.signal()
+      return 1.0
+    }
     var gammaTableRed = [CGGammaValue](repeating: 0, count: 256)
     var gammaTableGreen = [CGGammaValue](repeating: 0, count: 256)
     var gammaTableBlue = [CGGammaValue](repeating: 0, count: 256)
@@ -297,24 +308,26 @@ class Display: Equatable {
     os_log("Gamma table interference detected, number of events: %{public}@", type: .info, String(DisplayManager.shared.gammaInterferenceCounter))
     if DisplayManager.shared.gammaInterferenceCounter >= 3 {
       DisplayManager.shared.gammaInterferenceWarningShown = true
-      let alert = NSAlert()
-      alert.messageText = NSLocalizedString("Is f.lux or similar running?", comment: "Shown in the alert dialog")
-      alert.informativeText = NSLocalizedString("An other app seems to change the brightness or colors which causes issues.\n\nTo solve this, you need to quit the other app or disable gamma control for your displays in MonitorControl!", comment: "Shown in the alert dialog")
-      alert.addButton(withTitle: NSLocalizedString("I'll quit the other app", comment: "Shown in the alert dialog"))
-      alert.addButton(withTitle: NSLocalizedString("Disable gamma control for my displays", comment: "Shown in the alert dialog"))
-      alert.alertStyle = NSAlert.Style.critical
-      if alert.runModal() != .alertFirstButtonReturn {
-        for otherDisplay in DisplayManager.shared.getOtherDisplays() {
-          _ = otherDisplay.setSwBrightness(1)
-          _ = otherDisplay.setDirectBrightness(1)
-          otherDisplay.savePref(true, key: .avoidGamma)
-          _ = otherDisplay.setSwBrightness(1)
-          DisplayManager.shared.gammaInterferenceWarningShown = false
-          DisplayManager.shared.gammaInterferenceCounter = 0
-          displaysPrefsVc?.loadDisplayList()
+      DispatchQueue.main.async {
+        let alert = NSAlert()
+        alert.messageText = NSLocalizedString("Is f.lux or similar running?", comment: "Shown in the alert dialog")
+        alert.informativeText = NSLocalizedString("An other app seems to change the brightness or colors which causes issues.\n\nTo solve this, you need to quit the other app or disable gamma control for your displays in MonitorControl!", comment: "Shown in the alert dialog")
+        alert.addButton(withTitle: NSLocalizedString("I'll quit the other app", comment: "Shown in the alert dialog"))
+        alert.addButton(withTitle: NSLocalizedString("Disable gamma control for my displays", comment: "Shown in the alert dialog"))
+        alert.alertStyle = NSAlert.Style.critical
+        if alert.runModal() != .alertFirstButtonReturn {
+          for otherDisplay in DisplayManager.shared.getOtherDisplays() {
+            _ = otherDisplay.setSwBrightness(1)
+            _ = otherDisplay.setDirectBrightness(1)
+            otherDisplay.savePref(true, key: .avoidGamma)
+            _ = otherDisplay.setSwBrightness(1)
+            DisplayManager.shared.gammaInterferenceWarningShown = false
+            DisplayManager.shared.gammaInterferenceCounter = 0
+            displaysPrefsVc?.loadDisplayList()
+          }
+        } else {
+          os_log("We won't watch for gamma table interference anymore", type: .info)
         }
-      } else {
-        os_log("We won't watch for gamma table interference anymore", type: .info)
       }
     }
   }

diff --git a/MonitorControl/Model/OtherDisplay.swift b/MonitorControl/Model/OtherDisplay.swift
@@ -97,9 +97,6 @@ class OtherDisplay: Display {
     case .contrast: currentDDCValue = UInt16(Float(DDC_MAX_DETECT_LIMIT) * 0.750)
     default: currentDDCValue = UInt16(Float(DDC_MAX_DETECT_LIMIT) * 1.000)
     }
-    if command == .audioSpeakerVolume {
-      currentDDCValue = UInt16(Float(DDC_MAX_DETECT_LIMIT) * 0.125) // lower default audio value as high volume might rattle the user.
-    }
     os_log("Setting up display %{public}@ for %{public}@", type: .info, String(self.identifier), String(reflecting: command))
     if !self.isSw() {
       if prefs.integer(forKey: PrefKey.startupAction.rawValue) == StartupAction.read.rawValue, self.pollingCount != 0, !app.safeMode {
@@ -399,21 +396,32 @@ class OtherDisplay: Display {
     guard value != UInt16.max, value != lastValue else {
       return
     }
-    self.writeDDCQueue.async(flags: .barrier) {
-      self.writeDDCLastSavedValue[command] = value
-      self.savePref(true, key: PrefKey.isTouched, for: command)
-    }
     var controlCodes = self.getRemapControlCodes(command: command)
     if controlCodes.count == 0 {
       controlCodes.append(command.rawValue)
     }
+    var writeAttempted = false
+    var writeSucceeded = true
     for controlCode in controlCodes {
       if Arm64DDC.isArm64 {
         if self.arm64ddc {
-          _ = Arm64DDC.write(service: self.arm64avService, command: controlCode, value: value)
+          writeAttempted = true
+          writeSucceeded = Arm64DDC.write(service: self.arm64avService, command: controlCode, value: value)
         }
       } else {
-        _ = self.ddc?.write(command: controlCode, value: value, errorRecoveryWaitTime: 2000) ?? false
+        if self.ddc != nil {
+          writeAttempted = true
+          writeSucceeded = self.ddc?.write(command: controlCode, value: value, errorRecoveryWaitTime: 2000) ?? false
+        }
+      }
+      if writeAttempted, !writeSucceeded {
+        break
+      }
+    }
+    if writeAttempted, writeSucceeded {
+      self.writeDDCQueue.async(flags: .barrier) {
+        self.writeDDCLastSavedValue[command] = value
+        self.savePref(true, key: PrefKey.isTouched, for: command)
       }
     }
   }
@@ -487,6 +495,9 @@ class OtherDisplay: Display {
     let curveMultiplier = self.getCurveMultiplier(self.readPrefAsInt(key: .curveDDC, for: command))
     let minDDCValue = Float(self.readPrefAsInt(key: .minDDCOverride, for: command))
     let maxDDCValue = Float(self.readPrefAsInt(key: .maxDDC, for: command))
+    guard maxDDCValue != minDDCValue else {
+      return UInt16(minDDCValue)
+    }
     let curvedValue = pow(max(min(value, 1), 0), curveMultiplier)
     let deNormalizedValue = (maxDDCValue - minDDCValue) * curvedValue + minDDCValue
     var intDDCValue = UInt16(min(max(deNormalizedValue.rounded(), minDDCValue), maxDDCValue))
@@ -500,6 +511,9 @@ class OtherDisplay: Display {
     let curveMultiplier = self.getCurveMultiplier(self.readPrefAsInt(key: .curveDDC, for: command))
     let minDDCValue = Float(self.readPrefAsInt(key: .minDDCOverride, for: command))
     let maxDDCValue = Float(self.readPrefAsInt(key: .maxDDC, for: command))
+    guard maxDDCValue != minDDCValue else {
+      return 0
+    }
     let normalizedValue = ((min(max(Float(from), minDDCValue), maxDDCValue) - minDDCValue) / (maxDDCValue - minDDCValue))
     let deCurvedValue = pow(normalizedValue, 1.0 / curveMultiplier)
     var value = deCurvedValue

diff --git a/MonitorControl/Support/AppDelegate.swift b/MonitorControl/Support/AppDelegate.swift
@@ -23,6 +23,7 @@ class AppDelegate: NSObject, NSApplicationDelegate {
   var accessibilityObserver: NSObjectProtocol!
   var statusItemObserver: NSObjectProtocol!
   var statusItemVisibilityChangedByUser = true
+  var configureID: Int = 0 // dispatched configure command ID
   var reconfigureID: Int = 0 // dispatched reconfigure command ID
   var sleepID: Int = 0 // sleep event ID
   var safeMode = false
@@ -156,22 +157,45 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     }
     os_log("Request for configuration with reconfigreID %{public}@", type: .info, String(dispatchedReconfigureID))
     self.reconfigureID = 0
+    self.configureID += 1
+    let dispatchedConfigureID = self.configureID
     DisplayManager.shared.gammaInterferenceCounter = 0
     DisplayManager.shared.configureDisplays()
     DisplayManager.shared.addDisplayCounterSuffixes()
     DisplayManager.shared.updateArm64AVServices()
     if firstrun && prefs.integer(forKey: PrefKey.startupAction.rawValue) != StartupAction.write.rawValue {
       DisplayManager.shared.resetSwBrightnessForAllDisplays(prefsOnly: true)
     }
-    DisplayManager.shared.setupOtherDisplays(firstrun: firstrun)
-    self.updateMenusAndKeys()
-    if !firstrun || prefs.integer(forKey: PrefKey.startupAction.rawValue) == StartupAction.write.rawValue {
-      if !prefs.bool(forKey: PrefKey.disableCombinedBrightness.rawValue) {
-        DisplayManager.shared.restoreSwBrightnessForAllDisplays(async: !prefs.bool(forKey: PrefKey.disableSmoothBrightness.rawValue))
+    DispatchQueue.global(qos: .userInitiated).async {
+      guard self.sleepID == 0, self.reconfigureID == 0, dispatchedConfigureID == self.configureID else {
+        return
+      }
+      DisplayManager.shared.setupOtherDisplays(firstrun: firstrun)
+      guard self.sleepID == 0, self.reconfigureID == 0, dispatchedConfigureID == self.configureID else {
+        return
+      }
+      DispatchQueue.main.async {
+        guard self.sleepID == 0, self.reconfigureID == 0, dispatchedConfigureID == self.configureID else {
+          return
+        }
+        self.updateMenusAndKeys()
+      }
+      guard self.sleepID == 0, self.reconfigureID == 0, dispatchedConfigureID == self.configureID else {
+        return
+      }
+      if !firstrun || prefs.integer(forKey: PrefKey.startupAction.rawValue) == StartupAction.write.rawValue {
+        if !prefs.bool(forKey: PrefKey.disableCombinedBrightness.rawValue) {
+          DisplayManager.shared.restoreSwBrightnessForAllDisplays(async: !prefs.bool(forKey: PrefKey.disableSmoothBrightness.rawValue))
+        }
+      }
+      DispatchQueue.main.async {
+        guard self.sleepID == 0, self.reconfigureID == 0, dispatchedConfigureID == self.configureID else {
+          return
+        }
+        displaysPrefsVc?.loadDisplayList()
+        self.job(start: true)
       }
     }
-    displaysPrefsVc?.loadDisplayList()
-    self.job(start: true)
   }
 
   func updateMenusAndKeys() {
@@ -318,22 +342,25 @@ class AppDelegate: NSObject, NSApplicationDelegate {
   }
 
   func setStartAtLogin(enabled: Bool) {
-    let identifier = "\(Bundle.main.bundleIdentifier!)Helper" as CFString
-    SMLoginItemSetEnabled(identifier, enabled)
+    let identifier = "\(Bundle.main.bundleIdentifier!)Helper"
+    if #available(macOS 13.0, *) {
+      let service = SMAppService.loginItem(identifier: identifier)
+      do {
+        if enabled {
+          try service.register()
+        } else {
+          try service.unregister()
+        }
+      } catch {
+        os_log("Unable to update login item registration: %{public}@", type: .error, error.localizedDescription)
+      }
+    } else {
+      SMLoginItemSetEnabled(identifier as CFString, enabled)
+    }
   }
 
-  func getSystemSettings() -> [String: AnyObject]? {
-    var propertyListFormat = PropertyListSerialization.PropertyListFormat.xml
-    let plistPath = NSString(string: "~/Library/Preferences/.GlobalPreferences.plist").expandingTildeInPath
-    guard let plistXML = FileManager.default.contents(atPath: plistPath) else {
-      return nil
-    }
-    do {
-      return try PropertyListSerialization.propertyList(from: plistXML, options: .mutableContainersAndLeaves, format: &propertyListFormat) as? [String: AnyObject]
-    } catch {
-      os_log("Error reading system prefs plist: %{public}@", type: .info, error.localizedDescription)
-      return nil
-    }
+  func getSystemSettings() -> [String: Any]? {
+    UserDefaults.standard.persistentDomain(forName: ".GlobalPreferences")
   }
 
   func macOS10() -> Bool {

diff --git a/MonitorControl/Support/Arm64DDC.swift b/MonitorControl/Support/Arm64DDC.swift
@@ -74,6 +74,9 @@ class Arm64DDC: NSObject {
     var send: [UInt8] = [command]
     var reply = [UInt8](repeating: 0, count: 11)
     if Self.performDDCCommunication(service: service, send: &send, reply: &reply, writeSleepTime: writeSleepTime, numOfWriteCycles: numOfWriteCycles, readSleepTime: readSleepTime, numOfRetryAttemps: numOfRetryAttemps, retrySleepTime: retrySleepTime) {
+      guard reply.count > 9, reply[0] == ARM64_DDC_7BIT_ADDRESS << 1, reply[2] == 0x02, reply[4] == command else {
+        return nil
+      }
       let max = UInt16(reply[6]) * 256 + UInt16(reply[7])
       let current = UInt16(reply[8]) * 256 + UInt16(reply[9])
       values = (current, max)
@@ -97,7 +100,8 @@ class Arm64DDC: NSObject {
     }
     var packet: [UInt8] = [UInt8(0x80 | (send.count + 1)), UInt8(send.count)] + send + [0] // Note: the last byte is the place of the checksum, see next line!
     packet[packet.count - 1] = self.checksum(chk: send.count == 1 ? ARM64_DDC_7BIT_ADDRESS << 1 : ARM64_DDC_7BIT_ADDRESS << 1 ^ dataAddress, data: &packet, start: 0, end: packet.count - 2)
-    for _ in 1 ... (numOfRetryAttemps ?? 4) + 1 {
+    let attempts = max(1, Int(min(numOfRetryAttemps ?? 4, UInt8(30))))
+    for _ in 0 ..< attempts {
       for _ in 1 ... max((numOfWriteCycles ?? 2) + 0, 1) {
         usleep(writeSleepTime ?? 10000)
         success = IOAVServiceWriteI2C(service, UInt32(ARM64_DDC_7BIT_ADDRESS), UInt32(dataAddress), &packet, UInt32(packet.count)) == 0
@@ -232,7 +236,13 @@ class Arm64DDC: NSObject {
   static func getIoregServicesForMatching() -> [IOregService] {
     var serviceLocation = 0
     var ioregServicesForMatching: [IOregService] = []
-    let ioregRoot: io_registry_entry_t = IORegistryGetRootEntry(kIOMasterPortDefault)
+    let masterPort: mach_port_t
+    if #available(macOS 12.0, *) {
+      masterPort = kIOMainPortDefault
+    } else {
+      masterPort = kIOMasterPortDefault
+    }
+    let ioregRoot: io_registry_entry_t = IORegistryGetRootEntry(masterPort)
     defer {
       IOObjectRelease(ioregRoot)
     }

diff --git a/MonitorControl/Support/DisplayManager.swift b/MonitorControl/Support/DisplayManager.swift
@@ -42,7 +42,6 @@ class DisplayManager {
   }
 
   var shades: [CGDirectDisplayID: NSWindow] = [:]
-  var shadeGrave: [NSWindow] = []
 
   func isDisqualifiedFromShade(_ displayID: CGDirectDisplayID) -> Bool {
     if CGDisplayIsInHWMirrorSet(displayID) != 0 || CGDisplayIsInMirrorSet(displayID) != 0 {
@@ -117,7 +116,6 @@ class DisplayManager {
   func destroyShade(displayID: CGDirectDisplayID) -> Bool {
     if let shade = shades[displayID] {
       os_log("Destroying shade for display %{public}@", type: .info, String(displayID))
-      self.shadeGrave.append(shade)
       self.shades.removeValue(forKey: displayID)
       shade.close()
       return true
@@ -241,21 +239,6 @@ class DisplayManager {
     self.displays.compactMap { $0 as? OtherDisplay }
   }
 
-  func sortDisplays() {
-    // Opsiyonel: sıralamadan önce log al
-    let before = self.displays.map(\.name)
-    os_log("Displays before sorting: %{public}@", before)
-
-    // In‑place sıralama
-    self.displays.sort { lhs, rhs in
-      lhs.name.localizedStandardCompare(rhs.name) == .orderedAscending
-    }
-
-    // Opsiyonel: sıralamadan sonra log al
-    let after = self.displays.map(\.name)
-    os_log("Displays after sorting: %{public}@", after)
-  }
-
   func sortDisplaysByFriendlyName() -> [Display] {
     self.displays.sorted { lhs, rhs in
       let lhsTitle = lhs.readPrefAsString(key: .friendlyName).isEmpty
@@ -337,11 +320,14 @@ class DisplayManager {
     if Arm64DDC.isArm64 {
       os_log("arm64 AVService update requested", type: .info)
       var displayIDs: [CGDirectDisplayID] = []
-      for otherDisplay in self.getOtherDisplays() {
+      let otherDisplays = self.getOtherDisplays()
+      for otherDisplay in otherDisplays {
+        otherDisplay.arm64avService = nil
+        otherDisplay.arm64ddc = false
         displayIDs.append(otherDisplay.identifier)
       }
       for serviceMatch in Arm64DDC.getServiceMatches(displayIDs: displayIDs) {
-        for otherDisplay in self.getOtherDisplays() where otherDisplay.identifier == serviceMatch.displayID && serviceMatch.service != nil {
+        for otherDisplay in otherDisplays where otherDisplay.identifier == serviceMatch.displayID && serviceMatch.service != nil {
           otherDisplay.arm64avService = serviceMatch.service
           os_log("Display service match successful for display %{public}@", type: .info, String(serviceMatch.displayID))
           if serviceMatch.discouraged {

diff --git a/MonitorControl/Support/MenuHandler.swift b/MonitorControl/Support/MenuHandler.swift
@@ -56,11 +56,12 @@ class MenuHandler: NSMenu, NSMenuDelegate {
     displays = DisplayManager.shared.sortDisplaysByFriendlyName()
     let relevant = prefs.integer(forKey: PrefKey.multiSliders.rawValue) == MultiSliders.relevant.rawValue
     let combine = prefs.integer(forKey: PrefKey.multiSliders.rawValue) == MultiSliders.combine.rawValue
+    let currentDisplayID = currentDisplay.map { DisplayManager.resolveEffectiveDisplayID($0.identifier) }
     let numOfDisplays = displays.filter { !$0.isDummy }.count
     if numOfDisplays != 0 {
       let asSubMenu: Bool = (displays.count > 3 && !relevant && !combine && app.macOS10()) ? true : false
       var iterator = 0
-      for display in displays where (!relevant || DisplayManager.resolveEffectiveDisplayID(display.identifier) == DisplayManager.resolveEffectiveDisplayID(currentDisplay!.identifier)) && !display.isDummy {
+      for display in displays where (!relevant || currentDisplayID.map { DisplayManager.resolveEffectiveDisplayID(display.identifier) == $0 } ?? false) && !display.isDummy {
         iterator += 1
         if !relevant, !combine, iterator != 1, app.macOS10() {
           self.insertItem(NSMenuItem.separator(), at: 0)