Add a clean up process on the device

In order to clean up on close, use a separate process which is not
killed when the device is disconnected (even if the main process itself
is killed).

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

@@ -0,0 +1,62 @@
+package com.genymobile.scrcpy;
+
+import com.genymobile.scrcpy.wrappers.ContentProvider;
+import com.genymobile.scrcpy.wrappers.ServiceManager;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Handle the cleanup of scrcpy, even if the main process is killed.
+ * <p>
+ * This is useful to restore some state when scrcpy is closed, even on device disconnection (which kills the scrcpy process).
+ */
+public final class CleanUp {
+
+    public static final String SERVER_PATH = "/data/local/tmp/scrcpy-server.jar";
+
+    private CleanUp() {
+        // not instantiable
+    }
+
+    public static void configure() throws IOException {
+        // TODO
+        boolean needProcess = false;
+        if (needProcess) {
+            startProcess();
+        } else {
+            // There is no additional clean up to do when scrcpy dies
+            unlinkSelf();
+        }
+    }
+
+    private static void startProcess() throws IOException {
+        String[] cmd = {"app_process", "/", CleanUp.class.getName()};
+
+        ProcessBuilder builder = new ProcessBuilder(cmd);
+        builder.environment().put("CLASSPATH", SERVER_PATH);
+        builder.start();
+    }
+
+    private static void unlinkSelf() {
+        try {
+            new File(SERVER_PATH).delete();
+        } catch (Exception e) {
+            Ln.e("Could not unlink server", e);
+        }
+    }
+
+    public static void main(String... args) {
+        unlinkSelf();
+
+        try {
+            // Wait for the server to die
+            System.in.read();
+        } catch (IOException e) {
+            // Expected when the server is dead
+        }
+
+        Ln.i("Cleaning up");
+        // TODO
+    }
+}

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

@@ -4,12 +4,10 @@ import android.graphics.Rect;
 import android.media.MediaCodec;
 import android.os.Build;
 
-import java.io.File;
 import java.io.IOException;
 
 public final class Server {
 
-    private static final String SERVER_PATH = "/data/local/tmp/scrcpy-server.jar";
 
     private Server() {
         // not instantiable
@@ -18,6 +16,9 @@ public final class Server {
     private static void scrcpy(Options options) throws IOException {
         Ln.i("Device: " + Build.MANUFACTURER + " " + Build.MODEL + " (Android " + Build.VERSION.RELEASE + ")");
         final Device device = new Device(options);
+
+        CleanUp.configure();
+
         boolean tunnelForward = options.isTunnelForward();
         try (DesktopConnection connection = DesktopConnection.open(device, tunnelForward)) {
             ScreenEncoder screenEncoder = new ScreenEncoder(options.getSendFrameMeta(), options.getBitRate(), options.getMaxFps());
@@ -132,14 +133,6 @@ public final class Server {
         return new Rect(x, y, x + width, y + height);
     }
 
-    private static void unlinkSelf() {
-        try {
-            new File(SERVER_PATH).delete();
-        } catch (Exception e) {
-            Ln.e("Could not unlink server", e);
-        }
-    }
-
     private static void suggestFix(Throwable e) {
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
             if (e instanceof MediaCodec.CodecException) {
@@ -172,7 +165,6 @@ public final class Server {
             }
         });
 
-        unlinkSelf();
         Options options = createOptions(args);
         scrcpy(options);
     }