Read/write settings via command on Android >= 12

Before Android 8, executing the "settings" command from a shell was
very slow (~1 second), because it spawned a new app_process to execute
Java code. Therefore, to access settings without performance issues,
scrcpy used private APIs to read from and write to settings.

However, since Android 12, this is not possible anymore, due to
permissions changes.

To make it work again, execute the "settings" command on Android 12 (or
on previous version if the other method failed). This method is faster
than before Android 8 (~100ms).

Fixes #2671 <https://github.com/Genymobile/scrcpy/issues/2671>
Fixes #2788 <https://github.com/Genymobile/scrcpy/issues/2788>
PR #2802 <https://github.com/Genymobile/scrcpy/pull/2802>

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

@@ -0,0 +1,33 @@
+package com.genymobile.scrcpy;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Scanner;
+
+public final class Command {
+    private Command() {
+        // not instantiable
+    }
+
+    public static void exec(String... cmd) throws IOException, InterruptedException {
+        Process process = Runtime.getRuntime().exec(cmd);
+        int exitCode = process.waitFor();
+        if (exitCode != 0) {
+            throw new IOException("Command " + Arrays.toString(cmd) + " returned with value " + exitCode);
+        }
+    }
+
+    public static String execReadLine(String... cmd) throws IOException, InterruptedException {
+        String result = null;
+        Process process = Runtime.getRuntime().exec(cmd);
+        Scanner scanner = new Scanner(process.getInputStream());
+        if (scanner.hasNextLine()) {
+            result = scanner.nextLine();
+        }
+        int exitCode = process.waitFor();
+        if (exitCode != 0) {
+            throw new IOException("Command " + Arrays.toString(cmd) + " returned with value " + exitCode);
+        }
+        return result;
+    }
+}

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

@@ -3,6 +3,10 @@ package com.genymobile.scrcpy;
 import com.genymobile.scrcpy.wrappers.ContentProvider;
 import com.genymobile.scrcpy.wrappers.ServiceManager;
 
+import android.os.Build;
+
+import java.io.IOException;
+
 public class Settings {
 
     public static final String TABLE_SYSTEM = ContentProvider.TABLE_SYSTEM;
@@ -15,25 +19,66 @@ public class Settings {
         this.serviceManager = serviceManager;
     }
 
+    private static void execSettingsPut(String table, String key, String value) throws SettingsException {
+        try {
+            Command.exec("settings", "put", table, key, value);
+        } catch (IOException | InterruptedException e) {
+            throw new SettingsException("put", table, key, value, e);
+        }
+    }
+
+    private static String execSettingsGet(String table, String key) throws SettingsException {
+        try {
+            return Command.execReadLine("settings", "get", table, key);
+        } catch (IOException | InterruptedException e) {
+            throw new SettingsException("get", table, key, null, e);
+        }
+    }
+
     public String getValue(String table, String key) throws SettingsException {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.R) {
+            // on Android >= 12, it always fails: <https://github.com/Genymobile/scrcpy/issues/2788>
             try (ContentProvider provider = serviceManager.getActivityManager().createSettingsProvider()) {
                 return provider.getValue(table, key);
+            } catch (SettingsException e) {
+                Ln.w("Could not get settings value via ContentProvider, fallback to settings process", e);
             }
         }
 
+        return execSettingsGet(table, key);
+    }
+
     public void putValue(String table, String key, String value) throws SettingsException {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.R) {
+            // on Android >= 12, it always fails: <https://github.com/Genymobile/scrcpy/issues/2788>
             try (ContentProvider provider = serviceManager.getActivityManager().createSettingsProvider()) {
                 provider.putValue(table, key, value);
+            } catch (SettingsException e) {
+                Ln.w("Could not put settings value via ContentProvider, fallback to settings process", e);
             }
         }
 
+        execSettingsPut(table, key, value);
+    }
+
     public String getAndPutValue(String table, String key, String value) throws SettingsException {
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.R) {
+            // on Android >= 12, it always fails: <https://github.com/Genymobile/scrcpy/issues/2788>
             try (ContentProvider provider = serviceManager.getActivityManager().createSettingsProvider()) {
                 String oldValue = provider.getValue(table, key);
                 if (!value.equals(oldValue)) {
                     provider.putValue(table, key, value);
                 }
                 return oldValue;
+            } catch (SettingsException e) {
+                Ln.w("Could not get and put settings value via ContentProvider, fallback to settings process", e);
             }
         }
+
+        String oldValue = getValue(table, key);
+        if (!value.equals(oldValue)) {
+             putValue(table, key, value);
+        }
+        return oldValue;
+    }
 }