GN: Side-load dex files as well as native code in incremental installs

build/android/incremental_install/java/org/chromium/incrementalinstall/BootstrapApplication.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.incrementalinstall;

[nyquist, 2015/09/16 06:30:45]

Optional nit: How do you feel about org.chromium.build.incrementalinstall? I
don't feel strongly though, since it's kind of a standalone thing.

[agrieve, 2015/09/16 14:59:58]

All the same to me, so will leave it if you don't really care.

+
+import android.app.Application;
+import android.content.Context;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.util.Log;
+
+import java.io.File;
+import java.lang.ref.WeakReference;
+import java.lang.reflect.InvocationTargetException;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * An Application that replaces itself with another Application (as defined in
+ * the "incremental-install-real-app" meta-data tag within the
+ * AndroidManifest.xml). It loads the other application only after side-loading
+ * its .so and .dex files from /data/local/tmp.
+ */
+public final class BootstrapApplication extends Application {
+    private static final String TAG = "cr.incrementalinstall";
+    private static final String MANAGED_DIR_PREFIX = "/data/local/tmp/incremental-app-";
+    private static final String REAL_APP_META_DATA_NAME = "incremental-install-real-app";
+
+    private ClassLoaderPatcher mClassLoaderPatcher;
+    private Application mRealApplication;
+    private Object mStashedProviderList;
+    private Object mActivityThread;
+
+    @Override
+    protected void attachBaseContext(Context context) {
+        super.attachBaseContext(context);
+        File incrementalRootDir = new File(MANAGED_DIR_PREFIX + context.getPackageName());
+        File libDir = new File(incrementalRootDir, "lib");
+        File dexDir = new File(incrementalRootDir, "dex");
+        File installLockFile = new File(incrementalRootDir, "install.lock");
+        File firstRunLockFile = new File(incrementalRootDir, "firstrun.lock");
+
+        try {
+            mActivityThread = Reflect.invokeMethod(Class.forName("android.app.ActivityThread"),
+                    "currentActivityThread");
+            mClassLoaderPatcher = new ClassLoaderPatcher(context);
+
+            boolean isFirstRun = LockFile.installerLockExists(firstRunLockFile);
+            if (isFirstRun && mClassLoaderPatcher.mIsPrimaryProcess) {

[nyquist, 2015/09/16 06:30:45]

Nit: I know it would be an additional indent, but I find it easier to read:
if (isFirstRun) {
  if (...isPrimary...) {
    ..install..
  } else {
    ..firstRun..
  }
}

I think that should yield the same result?

Or where you trying to keep the same format for the if-statement as below where
you clear the installer lock for first run?

[agrieve, 2015/09/16 14:59:58]

Done.

+                // Wait for incremental_install.py to finish.
+                LockFile.waitForInstallerLock(installLockFile, 20 * 1000);
+            } else if (isFirstRun) {
+                // Wait for the browser process to create the optimized dex files
+                // (and for M+, copy the library files).
+                LockFile.waitForInstallerLock(firstRunLockFile, 30 * 1000);
+            }
+
+            mClassLoaderPatcher.importNativeLibs(libDir);
+            mClassLoaderPatcher.loadDexFiles(dexDir);
+
+            if (isFirstRun && mClassLoaderPatcher.mIsPrimaryProcess) {
+                LockFile.clearInstallerLock(firstRunLockFile);
+            }
+
+            // attachBaseContext() is called from ActivityThread#handleBindApplication() and
+            // Application#mApplication is changed right after we return. Thus, we cannot swap
+            // the Application instances until onCreate() is called.
+            String mRealApplicationName = getRealApplicationName();

[nyquist, 2015/09/16 06:30:45]

Nit: Just |realApplicationName|

[agrieve, 2015/09/16 14:59:58]

Done.

+            Log.i(TAG, "Instantiating " + mRealApplicationName);
+            mRealApplication =
+                    (Application) Reflect.newInstance(Class.forName(mRealApplicationName));
+            Reflect.invokeMethod(mRealApplication, "attachBaseContext", context);
+
+            // Between attachBaseContext() and onCreate(), ActivityThread tries to instantiate
+            // all ContentProviders. The ContentProviders break without the correct Application
+            // class being installed, so temporarily pretend there are no providers, and then
+            // instantiate them explicitly within onCreate().
+            disableContentProviders();
+            Log.i(TAG, "Waiting for onCreate");
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        try {
+            Log.i(TAG, "onCreate() called. Swapping Application references");
+            swapApplicationReferences();
+            enableContentProviders();
+            Log.i(TAG, "Calling onCreate");
+            mRealApplication.onCreate();
+        } catch (Exception e) {
+            throw new RuntimeException(e);

[nyquist, 2015/09/16 06:30:45]

Nit: I know we log that we're trying above here, but could we add a short
message to the exception here saying that this magically cool thing failed?

[agrieve, 2015/09/16 14:59:58]

Done.

+        }
+    }
+
+    /**
+     * Returns the class name of the real Application class (recorded in the
+     * AndroidManifest.xml)
+     */
+    private String getRealApplicationName() throws NameNotFoundException {
+        ApplicationInfo appInfo = getPackageManager().getApplicationInfo(getPackageName(),
+                PackageManager.GET_META_DATA);
+        return appInfo.metaData.getString(REAL_APP_META_DATA_NAME);
+    }
+
+    /**
+     * Nulls out ActivityThread.mBoundApplication.providers.
+     */
+    private void disableContentProviders() throws NoSuchFieldException {
+        Object data = Reflect.getField(mActivityThread, "mBoundApplication");
+        mStashedProviderList = Reflect.getField(data, "providers");
+        Reflect.setField(data, "providers", null);
+    }
+
+    /**
+     * Restores the value of ActivityThread.mBoundApplication.providers, and invokes
+     * ActivityThread#installContentProviders().
+     */
+    private void enableContentProviders() throws NoSuchMethodException, InvocationTargetException,
+            NoSuchFieldException {
+        Object data = Reflect.getField(mActivityThread, "mBoundApplication");
+        Reflect.setField(data, "providers", mStashedProviderList);
+        if (mStashedProviderList != null && mClassLoaderPatcher.mIsPrimaryProcess) {
+            Log.i(TAG, "Instantiating content providers");
+            Reflect.invokeMethod(mActivityThread, "installContentProviders", mRealApplication,
+                    mStashedProviderList);
+        }
+        mStashedProviderList = null;
+    }
+
+    /**
+     * Changes all fields within framework classes that have stored an reference to this
+     * BootstrapApplication to instead store references to mRealApplication.
+     * @throws NoSuchFieldException
+     */
+    @SuppressWarnings("unchecked")
+    private void swapApplicationReferences() throws NoSuchFieldException {
+        if (Reflect.getField(mActivityThread, "mInitialApplication") == this) {
+            Reflect.setField(mActivityThread, "mInitialApplication", mRealApplication);
+        }
+
+        List<Application> allApplications =
+                (List<Application>) Reflect.getField(mActivityThread, "mAllApplications");
+        for (int i = 0; i < allApplications.size(); i++) {
+            if (allApplications.get(i) == this) {
+                allApplications.set(i, mRealApplication);
+            }
+        }
+
+        for (String fieldName : new String[] { "mPackages", "mResourcePackages" }) {
+            Map<String, WeakReference<?>> packageMap =
+                    (Map<String, WeakReference<?>>) Reflect.getField(mActivityThread, fieldName);
+            for (Map.Entry<String, WeakReference<?>> entry : packageMap.entrySet()) {
+                Object loadedApk = entry.getValue().get();
+                if (loadedApk != null && Reflect.getField(loadedApk, "mApplication") == this) {
+                    Reflect.setField(loadedApk, "mApplication", mRealApplication);
+                    Reflect.setField(mRealApplication, "mLoadedApk", loadedApk);
+                }
+            }
+        }
+    }
+}