Fix turn screen off on Android 14

On Android 14, execute a separate process with a different classpath and
LD_PRELOAD to execute the methods required to turn the device screen
off.

Fixes #3927 <#3927>
Refs #3927 comment <#3927 (comment)>
PR #4446 <#4446>

Co-authored-by: Simon Chan <[email protected]>

server/src/main/java/com/genymobile/scrcpy/CleanUp.java

@@ -183,6 +183,8 @@ public static void main(String... args) {
             } else if (config.restoreNormalPowerMode) {
                 Ln.i("Restoring normal power mode");
                 Device.setScreenPowerMode(Device.POWER_MODE_NORMAL);
+                // Make sure the request is performed before exiting
+                DisplayPowerMode.stopAndJoin();
             }
         }
 

server/src/main/java/com/genymobile/scrcpy/Device.java

@@ -315,6 +315,14 @@ public boolean setClipboardText(String text) {
      */
     public static boolean setScreenPowerMode(int mode) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE && !SurfaceControl.hasPhysicalDisplayIdsMethod()) {
+                // On Android 14+, these internal methods have been moved to system server classes.
+                // Run a separate process with the correct classpath and LD_PRELOAD to change the display power mode.
+                DisplayPowerMode.setRemoteDisplayPowerMode(mode);
+                // The call is asynchronous (we don't want to block)
+                return true;
+            }
+
             // Change the power mode for all physical displays
             long[] physicalDisplayIds = SurfaceControl.getPhysicalDisplayIds();
             if (physicalDisplayIds == null) {

server/src/main/java/com/genymobile/scrcpy/DisplayPowerMode.java

@@ -0,0 +1,161 @@
+package com.genymobile.scrcpy;
+
+import android.annotation.SuppressLint;
+import android.os.IBinder;
+
+import java.io.IOException;
+import java.lang.reflect.Method;
+
+/**
+ * On Android 14, the methods used to turn the device screen off have been moved from SurfaceControl (in framework.jar) to DisplayControl (a system
+ * server class). As a consequence, they could not be called directly. See {@url https://github.com/Genymobile/scrcpy/issues/3927}.
+ * <p>
+ * Instead, run a separate process with a different classpath and LD_PRELOAD just to set the display power mode.
+ * <p>
+ * Since the client must not block, and calling/joining a process is blocking (this specific one takes a few hundred milliseconds to complete),
+ * this class uses an internal thread to execute the requests asynchronously, and serialize them (so that two successive requests are guaranteed to
+ * be executed in order). In addition, it only executes the last pending request (setting power mode to value X then to value Y is equivalent to
+ * just setting it to value Y).
+ */
+public final class DisplayPowerMode {
+
+    private static final Proxy PROXY = new Proxy();
+
+    private static final class Proxy implements Runnable {
+
+        private Thread thread;
+        private int requestedMode = -1;
+        private boolean stopped;
+
+        synchronized void requestMode(int mode) {
+            if (thread == null) {
+                thread = new Thread(this, "DisplayPowerModeProxy");
+                thread.setDaemon(true);
+                thread.start();
+            }
+            requestedMode = mode;
+            notify();
+        }
+
+        void stopAndJoin() {
+            boolean hasThread;
+            synchronized (this) {
+                hasThread = thread != null;
+                if (thread != null) {
+                    stopped = true;
+                    notify();
+                }
+            }
+
+            if (hasThread) {
+                // Join the thread without holding the mutex (that would cause a deadlock)
+                try {
+                    thread.join();
+                } catch (InterruptedException e) {
+                    Ln.e("Thread join interrupted", e);
+                }
+            }
+        }
+
+        @Override
+        public void run() {
+            try {
+                int mode;
+                while (true) {
+                    synchronized (this) {
+                        while (!stopped && requestedMode == -1) {
+                            wait();
+                        }
+                        mode = requestedMode;
+                        requestedMode = -1;
+                    }
+
+                    // Even if stopped, the last request must be executed to restore the display power mode to normal
+                    if (mode == -1) {
+                        return;
+                    }
+
+                    try {
+                        Process process = executeSystemServerSetDisplayPowerMode(mode);
+                        int status = process.waitFor();
+                        if (status != 0) {
+                            Ln.e("Set display power mode failed remotely: status=" + status);
+                        }
+                    } catch (Exception e) {
+                        Ln.e("Failed to execute process", e);
+                    }
+                }
+            } catch (InterruptedException e) {
+                // end of thread
+            }
+        }
+    }
+
+    private DisplayPowerMode() {
+        // not instantiable
+    }
+
+    // Called from the scrcpy process
+    public static void setRemoteDisplayPowerMode(int mode) {
+        PROXY.requestMode(mode);
+    }
+
+    public static void stopAndJoin() {
+        PROXY.stopAndJoin();
+    }
+
+    // Called from the proxy thread in the scrcpy process
+    private static Process executeSystemServerSetDisplayPowerMode(int mode) throws IOException {
+        String[] ldPreloadLibs = {"/system/lib64/libandroid_servers.so"};
+        String[] cmd = {"app_process", "/", DisplayPowerMode.class.getName(), String.valueOf(mode)};
+
+        ProcessBuilder builder = new ProcessBuilder(cmd);
+        builder.environment().put("LD_PRELOAD", String.join(" ", ldPreloadLibs));
+        builder.environment().put("CLASSPATH", Server.SERVER_PATH + ":/system/framework/services.jar");
+        return builder.start();
+    }
+
+    // Executed in the DisplayPowerMode-specific process
+    @SuppressLint({"PrivateApi", "SoonBlockedPrivateApi"})
+    private static void setDisplayPowerModeUsingDisplayControl(int mode) throws Exception {
+        System.loadLibrary("android_servers");
+
+        @SuppressLint("PrivateApi")
+        Class<?> displayControlClass = Class.forName("com.android.server.display.DisplayControl");
+        Method getPhysicalDisplayIdsMethod = displayControlClass.getDeclaredMethod("getPhysicalDisplayIds");
+        Method getPhysicalDisplayTokenMethod = displayControlClass.getDeclaredMethod("getPhysicalDisplayToken", long.class);
+
+        Class<?> surfaceControlClass = Class.forName("android.view.SurfaceControl");
+        Method setDisplayPowerModeMethod = surfaceControlClass.getDeclaredMethod("setDisplayPowerMode", IBinder.class, int.class);
+
+        long[] displayIds = (long[]) getPhysicalDisplayIdsMethod.invoke(null);
+        for (long displayId : displayIds) {
+            Object token = getPhysicalDisplayTokenMethod.invoke(null, displayId);
+            setDisplayPowerModeMethod.invoke(null, token, mode);
+        }
+    }
+
+    public static void main(String... args) {
+        Ln.disableSystemStreams();
+        Ln.initLogLevel(Ln.Level.DEBUG);
+
+        int status = run(args) ? 0 : 1;
+        System.exit(status);
+    }
+
+    private static boolean run(String... args) {
+        if (args.length != 1) {
+            Ln.e("Exactly one argument expected: the value of one of the SurfaceControl.POWER_MODE_* constants (typically 0 or 2)");
+            return false;
+        }
+
+        try {
+            int mode = Integer.parseInt(args[0]);
+            setDisplayPowerModeUsingDisplayControl(mode);
+            return true;
+        } catch (Throwable e) {
+            Ln.e("Could not set display power mode", e);
+            return false;
+        }
+    }
+}

server/src/main/java/com/genymobile/scrcpy/wrappers/SurfaceControl.java

@@ -139,6 +139,15 @@ private static Method getGetPhysicalDisplayIdsMethod() throws NoSuchMethodExcept
         return getPhysicalDisplayIdsMethod;
     }
 
+    public static boolean hasPhysicalDisplayIdsMethod() {
+        try {
+            getGetPhysicalDisplayIdsMethod();
+            return true;
+        } catch (NoSuchMethodException e) {
+            return false;
+        }
+    }
+
     public static long[] getPhysicalDisplayIds() {
         try {
             Method method = getGetPhysicalDisplayIdsMethod();