Magisk/app/shared/src/main/java/com/topjohnwu/magisk/StubApk.java

package com.topjohnwu.magisk;

import static android.os.Build.VERSION.SDK_INT;
import static android.os.ParcelFileDescriptor.MODE_READ_ONLY;

import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.res.AssetManager;
import android.content.res.Resources;
import android.content.res.loader.ResourcesLoader;
import android.content.res.loader.ResourcesProvider;
import android.os.Build;
import android.os.ParcelFileDescriptor;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Map;

public class StubApk {
    private static File dynDir;
    private static Method addAssetPath;

    private static File getDynDir(ApplicationInfo info) {
        if (dynDir == null) {
            final String dataDir;
            if (SDK_INT >= Build.VERSION_CODES.N) {
                // Use device protected path to allow directBootAware
                dataDir = info.deviceProtectedDataDir;
            } else {
                dataDir = info.dataDir;
            }
            dynDir = new File(dataDir, "dyn");
            dynDir.mkdirs();
        }
        return dynDir;
    }

    public static File current(Context c) {
        return new File(getDynDir(c.getApplicationInfo()), "current.apk");
    }

    public static File current(ApplicationInfo info) {
        return new File(getDynDir(info), "current.apk");
    }

    public static File update(Context c) {
        return new File(getDynDir(c.getApplicationInfo()), "update.apk");
    }

    public static File update(ApplicationInfo info) {
        return new File(getDynDir(info), "update.apk");
    }

    @TargetApi(Build.VERSION_CODES.R)
    private static ResourcesLoader getResourcesLoader(File path) throws IOException {
        var loader = new ResourcesLoader();
        ResourcesProvider provider;
        if (path.isDirectory()) {
            provider = ResourcesProvider.loadFromDirectory(path.getPath(), null);
        } else {
            var fd = ParcelFileDescriptor.open(path, MODE_READ_ONLY);
            provider = ResourcesProvider.loadFromApk(fd);
        }
        loader.addProvider(provider);
        return loader;
    }

    public static void addAssetPath(Resources res, String path) {
        if (SDK_INT >= Build.VERSION_CODES.R) {
            try {
                res.addLoaders(getResourcesLoader(new File(path)));
            } catch (IOException ignored) {}
        } else {
            AssetManager asset = res.getAssets();
            try {
                if (addAssetPath == null)
                    addAssetPath = AssetManager.class.getMethod("addAssetPath", String.class);
                addAssetPath.invoke(asset, path);
            } catch (Exception ignored) {}
        }
    }

    public static void restartProcess(Activity activity) {
        Intent intent = activity.getPackageManager()
                .getLaunchIntentForPackage(activity.getPackageName());
        activity.finishAffinity();
        activity.startActivity(intent);
        Runtime.getRuntime().exit(0);
    }

    public static class Data {
        // Indices of the object array
        private static final int STUB_VERSION = 0;
        private static final int CLASS_COMPONENT_MAP = 1;
        private static final int ROOT_SERVICE = 2;
        private static final int ARR_SIZE = 3;

        private final Object[] arr;

        public Data() { arr = new Object[ARR_SIZE]; }
        public Data(Object o) { arr = (Object[]) o; }
        public Object getObject() { return arr; }

        public int getVersion() { return (int) arr[STUB_VERSION]; }
        public void setVersion(int version) { arr[STUB_VERSION] = version; }
        public Map<String, String> getClassToComponent() {
            // noinspection unchecked
            return (Map<String, String>) arr[CLASS_COMPONENT_MAP];
        }
        public void setClassToComponent(Map<String, String> map) {
            arr[CLASS_COMPONENT_MAP] = map;
        }
        public Class<?> getRootService() { return (Class<?>) arr[ROOT_SERVICE]; }
        public void setRootService(Class<?> service) { arr[ROOT_SERVICE] = service; }
    }
}