Support stub APK loading down to Android 5.0

stub/src/main/AndroidManifest.xml

@@ -13,7 +13,7 @@
         tools:ignore="GoogleAppIndexingWarning,MissingApplicationIcon,UnusedAttribute">
 
         <!-- Splash -->
-        <activity android:name="a.u7">
+        <activity android:name="f.u7">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
@@ -42,7 +42,7 @@
 
         <!-- Receiver -->
         <receiver
-            android:name="a.r"
+            android:name="yy.E"
             android:directBootAware="true"
             android:exported="false">
             <intent-filter>
@@ -61,7 +61,7 @@
 
         <!-- FileProvider -->
         <provider
-            android:name="a.ii"
+            android:name="fxQ.lk"
             android:authorities="${applicationId}.provider"
             android:directBootAware="true"
             android:exported="false"

stub/src/main/java/a/ii.java

@@ -1,5 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.FileProvider;
-
-public class ii extends FileProvider {}

stub/src/main/java/a/r.java

@@ -1,5 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.dummy.DummyReceiver;
-
-public class r extends DummyReceiver {}

stub/src/main/java/a/u7.java

@@ -1,5 +0,0 @@
-package a;
-
-import com.topjohnwu.magisk.DownloadActivity;
-
-public class u7 extends DownloadActivity {}

stub/src/main/java/com/topjohnwu/magisk/ClassLoaders.java

@@ -0,0 +1,33 @@
+package com.topjohnwu.magisk;
+
+import com.topjohnwu.magisk.utils.DynamicClassLoader;
+
+import java.io.File;
+
+class InjectedClassLoader extends DynamicClassLoader {
+
+    InjectedClassLoader(File apk) {
+        super(apk,
+                /* Use the base classloader as we do not want stub
+                 * APK classes accessible from the main app */
+                Object.class.getClassLoader());
+    }
+
+    @Override
+    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+        return super.loadClass(Mapping.get(name), resolve);
+    }
+}
+
+class RedirectClassLoader extends ClassLoader {
+
+    RedirectClassLoader() {
+        super(RedirectClassLoader.class.getClassLoader());
+    }
+
+    @Override
+    protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+        Class<?> clz = Mapping.internalMap.get(name);
+        return clz == null ? super.loadClass(name, resolve) : clz;
+    }
+}

stub/src/main/java/com/topjohnwu/magisk/DelegateApplication.java

@@ -10,32 +10,31 @@ import java.lang.reflect.Method;
 
 public class DelegateApplication extends Application {
 
-    private Application delegate;
     static boolean dynLoad = false;
 
+    private Application receiver;
+
     @Override
     protected void attachBaseContext(Context base) {
         super.attachBaseContext(base);
 
-        // Only dynamic load full APK if hidden and possible
+        // Only dynamic load full APK if hidden and supported
-        dynLoad = Build.VERSION.SDK_INT >= 28 &&
+        dynLoad = Build.VERSION.SDK_INT >= 21 &&
                 !base.getPackageName().equals(BuildConfig.APPLICATION_ID);
-        if (!dynLoad)
-            return;
 
-        delegate = InjectAPK.setup(this);
+        receiver = InjectAPK.setup(this);
-        if (delegate != null) try {
+        if (receiver != null) try {
             // Call attachBaseContext without ContextImpl to show it is being wrapped
             Method m = ContextWrapper.class.getDeclaredMethod("attachBaseContext", Context.class);
             m.setAccessible(true);
-            m.invoke(delegate, this);
+            m.invoke(receiver, this);
         } catch (Exception ignored) { /* Impossible */ }
     }
 
     @Override
     public void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
-        if (delegate != null)
+        if (receiver != null)
-            delegate.onConfigurationChanged(newConfig);
+            receiver.onConfigurationChanged(newConfig);
     }
 }

stub/src/main/java/com/topjohnwu/magisk/DelegateComponentFactory.java

@@ -9,22 +9,15 @@ import android.content.BroadcastReceiver;
 import android.content.ContentProvider;
 import android.content.Intent;
 
-import com.topjohnwu.magisk.dummy.DummyProvider;
-import com.topjohnwu.magisk.dummy.DummyReceiver;
-import com.topjohnwu.magisk.dummy.DummyService;
-
 @SuppressLint("NewApi")
 public class DelegateComponentFactory extends AppComponentFactory {
 
+    static DelegateComponentFactory INSTANCE;
     ClassLoader loader;
-    AppComponentFactory delegate;
+    AppComponentFactory receiver;
-
-    interface DummyFactory<T> {
-        T create();
-    }
 
     public DelegateComponentFactory() {
-        InjectAPK.factory = this;
+        INSTANCE = this;
     }
 
     @Override
@@ -36,45 +29,39 @@ public class DelegateComponentFactory extends AppComponentFactory {
     @Override
     public Activity instantiateActivity(ClassLoader cl, String className, Intent intent)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
-        if (delegate != null)
+        if (receiver != null)
-            return delegate.instantiateActivity(loader, Mapping.get(className), intent);
+            return receiver.instantiateActivity(loader, className, intent);
-        return create(className, DownloadActivity::new);
+        return create(className);
     }
 
     @Override
     public BroadcastReceiver instantiateReceiver(ClassLoader cl, String className, Intent intent)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
-        if (delegate != null)
+        if (receiver != null)
-            return delegate.instantiateReceiver(loader, Mapping.get(className), intent);
+            return receiver.instantiateReceiver(loader, className, intent);
-        return create(className, DummyReceiver::new);
+        return create(className);
     }
 
     @Override
     public Service instantiateService(ClassLoader cl, String className, Intent intent)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
-        if (delegate != null)
+        if (receiver != null)
-            return delegate.instantiateService(loader, Mapping.get(className), intent);
+            return receiver.instantiateService(loader, className, intent);
-        return create(className, DummyService::new);
+        return create(className);
     }
 
     @Override
     public ContentProvider instantiateProvider(ClassLoader cl, String className)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
         if (loader == null) loader = cl;
-        if (delegate != null)
+        if (receiver != null)
-            return delegate.instantiateProvider(loader, Mapping.get(className));
+            return receiver.instantiateProvider(loader, className);
-        return create(className, DummyProvider::new);
+        return create(className);
     }
 
-    /**
+    private <T> T create(String name)
-     * Create the class or dummy implementation if creation failed
+            throws ClassNotFoundException, IllegalAccessException, InstantiationException{
-     */
+        return (T) loader.loadClass(name).newInstance();
-    private <T> T create(String name, DummyFactory<T> factory) {
-        try {
-            return (T) loader.loadClass(name).newInstance();
-        } catch (Exception ignored) {
-            return factory.create();
-        }
     }
 
 }

stub/src/main/java/com/topjohnwu/magisk/InjectAPK.java

@@ -4,65 +4,97 @@ import android.app.AppComponentFactory;
 import android.app.Application;
 import android.content.ContentResolver;
 import android.content.Context;
+import android.content.ContextWrapper;
 import android.net.Uri;
+import android.os.Build;
 import android.util.Log;
 
-import com.topjohnwu.magisk.utils.DynamicClassLoader;
-
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.lang.reflect.Field;
 
 public class InjectAPK {
 
-    static DelegateComponentFactory factory;
+    @SuppressWarnings("ResultOfMethodCallIgnored")
-
     static Application setup(Context context) {
+        // Get ContextImpl
+        while (context instanceof ContextWrapper) {
+            context = ((ContextWrapper) context).getBaseContext();
+        }
+
         File apk = DynAPK.current(context);
         File update = DynAPK.update(context);
         if (update.exists())
             update.renameTo(apk);
-        Application delegate = null;
+        Application result = null;
         if (!apk.exists()) {
             // Try copying APK
             Uri uri = new Uri.Builder().scheme("content")
                     .authority("com.topjohnwu.magisk.provider")
                     .encodedPath("apk_file").build();
             ContentResolver resolver = context.getContentResolver();
-            try (InputStream is = resolver.openInputStream(uri)) {
+            try (InputStream src = resolver.openInputStream(uri)) {
-                if (is != null) {
+                if (src != null) {
                     try (OutputStream out = new FileOutputStream(apk)) {
                         byte[] buf = new byte[4096];
-                        for (int read; (read = is.read(buf)) >= 0;) {
+                        for (int read; (read = src.read(buf)) >= 0;) {
                             out.write(buf, 0, read);
                         }
                     }
                 }
-            } catch (Exception e) {
+            } catch (Exception ignored) {}
-                Log.e(InjectAPK.class.getSimpleName(), "", e);
-            }
         }
         if (apk.exists()) {
-            ClassLoader cl = new DynamicClassLoader(apk, factory.loader);
+            ClassLoader cl = new InjectedClassLoader(apk);
             try {
-                // Create the delegate AppComponentFactory
+                // Create the receiver Application
-                AppComponentFactory df = (AppComponentFactory)
+                Object app = cl.loadClass(Mapping.get("APP")).getConstructor(Object.class)
-                        cl.loadClass("androidx.core.app.CoreComponentFactory").newInstance();
-
-                // Create the delegate Application
-                delegate = (Application) cl.loadClass("a.e").getConstructor(Object.class)
                         .newInstance(DynAPK.pack(dynData()));
 
-                // If everything went well, set our loader and delegate
+                // Create the receiver component factory
-                factory.delegate = df;
+                Object factory = null;
-                factory.loader = cl;
+                if (Build.VERSION.SDK_INT >= 28) {
+                    factory = cl.loadClass(Mapping.get("ACF")).newInstance();
+                }
+
+                setClassLoader(context, cl);
+
+                // Finally, set variables
+                result = (Application) app;
+                if (Build.VERSION.SDK_INT >= 28) {
+                    DelegateComponentFactory.INSTANCE.loader = cl;
+                    DelegateComponentFactory.INSTANCE.receiver = (AppComponentFactory) factory;
+                }
             } catch (Exception e) {
                 Log.e(InjectAPK.class.getSimpleName(), "", e);
                 apk.delete();
             }
+        } else {
+            ClassLoader cl = new RedirectClassLoader();
+            try {
+                setClassLoader(context, cl);
+                if (Build.VERSION.SDK_INT >= 28) {
+                    DelegateComponentFactory.INSTANCE.loader = cl;
+                }
+            } catch (Exception e) {
+                // Should never happen
+                Log.e(InjectAPK.class.getSimpleName(), "", e);
+            }
         }
-        return delegate;
+        return result;
+    }
+
+    // Replace LoadedApk mClassLoader
+    private static void setClassLoader(Context impl, ClassLoader cl)
+            throws NoSuchFieldException, IllegalAccessException {
+        Field mInfo = impl.getClass().getDeclaredField("mPackageInfo");
+        mInfo.setAccessible(true);
+        Object loadedApk = mInfo.get(impl);
+        Field mcl = loadedApk.getClass().getDeclaredField("mClassLoader");
+        mcl.setAccessible(true);
+        mcl.set(loadedApk, cl);
     }
 
     private static DynAPK.Data dynData() {

stub/src/main/java/com/topjohnwu/magisk/Mapping.java

@@ -1,27 +1,42 @@
 package com.topjohnwu.magisk;
 
+import com.topjohnwu.magisk.dummy.DummyReceiver;
+
 import java.util.HashMap;
 import java.util.Map;
 
+/**
+ * These are just some random class names hardcoded as an example.
+ * For the actual release builds, these mappings will be auto generated.
+ */
 public class Mapping {
 
-    private static Map<String, String> map = new HashMap<>();
+    private static final Map<String, String> map = new HashMap<>();
-    public static Map<String, String> inverseMap;
+    public static final Map<String, Class<?>> internalMap = new HashMap<>();
+    public static final Map<String, String> inverseMap;
 
     static {
-        map.put("a.Qzw", "a.e");
+        map.put("a.Q", "com.topjohnwu.magisk.core.App");
-        map.put("a.u7", "a.c");
+        map.put("f.u7", "com.topjohnwu.magisk.core.SplashActivity");
-        map.put("a.ii", "a.p");
+        map.put("fxQ.lk", "com.topjohnwu.magisk.core.Provider");
-        map.put("a.r", "a.h");
+        map.put("yy.E", "com.topjohnwu.magisk.core.Receiver");
-        map.put("xt.R", "a.b");
+        map.put("xt.R", "com.topjohnwu.magisk.ui.MainActivity");
-        map.put("lt5.a", "a.m");
+        map.put("lt5.a", "com.topjohnwu.magisk.ui.surequest.SuRequestActivity");
-        map.put("d.s", "a.j");
+        map.put("d.s", "com.topjohnwu.magisk.core.download.DownloadService");
         map.put("w.d", "androidx.work.impl.background.systemjob.SystemJobService");
 
+        internalMap.put("a.Q", DelegateApplication.class);
+        internalMap.put("f.u7", DownloadActivity.class);
+        internalMap.put("fxQ.lk", FileProvider.class);
+        internalMap.put("yy.E", DummyReceiver.class);
+
         inverseMap = new HashMap<>(map.size());
         for (Map.Entry<String, String> e : map.entrySet()) {
             inverseMap.put(e.getValue(), e.getKey());
         }
+
+        map.put("APP", "com.topjohnwu.magisk.core.App");
+        map.put("ACF", "androidx.core.app.CoreComponentFactory");
     }
 
     public static String get(String name) {

stub/src/main/java/com/topjohnwu/magisk/dummy/DummyActivity.java

@@ -1,13 +0,0 @@
-package com.topjohnwu.magisk.dummy;
-
-import android.app.Activity;
-import android.os.Bundle;
-
-public class DummyActivity extends Activity {
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        finish();
-    }
-}

stub/src/main/java/com/topjohnwu/magisk/dummy/DummyService.java

@@ -1,13 +0,0 @@
-package com.topjohnwu.magisk.dummy;
-
-import android.app.Service;
-import android.content.Intent;
-import android.os.IBinder;
-
-public class DummyService extends Service {
-    @Override
-    public IBinder onBind(Intent intent) {
-        stopSelf();
-        return null;
-    }
-}