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

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

Index: build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
diff --git a/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java b/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
new file mode 100644
index 0000000000000000000000000000000000000000..66486c5f7ef23e7ae40e56113d087e961c21ba4d
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+++ b/build/android/incremental_install/java/org/chromium/incrementalinstall/ClassLoaderPatcher.java
@@ -0,0 +1,232 @@
+// 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;
+
+import android.content.Context;
+import android.os.Build;
+import android.util.Log;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.List;
+
+/**
+ * Provides the ability to add native libraries and .dex files to an existing class loader.
+ * Tested with Jellybean MR2 - Marshmellow.
+ */
+final class ClassLoaderPatcher {
+    private static final String TAG = "cr.incrementalinstall";
+    private final File mAppFilesSubDir;
+    private final ClassLoader mClassLoader;
+    private final Object mLibcoreOs;
+    private final int mProcessUid;
+    final boolean mIsPrimaryProcess;
+
+    ClassLoaderPatcher(Context context) throws ReflectiveOperationException {
+        mAppFilesSubDir =
+                new File(context.getApplicationInfo().dataDir, "incremental-install-files");
+        mClassLoader = context.getClassLoader();
+        mLibcoreOs = Reflect.getField(Class.forName("libcore.io.Libcore"), "os");
+        mProcessUid = (Integer) Reflect.invokeMethod(mLibcoreOs, "getuid");
+        mIsPrimaryProcess = context.getApplicationInfo().uid == mProcessUid;
+        Log.i(TAG, "uid=" + mProcessUid + " (isPrimary=" + mIsPrimaryProcess + ")");
+    }
+
+    /**
+     * Loads all dex files within |dexDir| into the app's ClassLoader.
+     */
+    void loadDexFiles(File dexDir) throws ReflectiveOperationException, FileNotFoundException {
+        Log.i(TAG, "Installing dex files from: " + dexDir);
+        File[] dexFilesArr = dexDir.listFiles();
+        if (dexFilesArr == null) {
+            throw new FileNotFoundException("Dex dir does not exist: " + dexDir);
+        }
+        // The optimized dex files will be owned by this process' user.
+        // Store them within the app's data dir rather than on /data/local/tmp
+        // so that they are still deleted (by the OS) when we uninstall
+        // (even on a non-rooted device).
+        File incrementalDexesDir = new File(mAppFilesSubDir, "optimized-dexes");
+        File isolatedDexesDir = new File(mAppFilesSubDir, "isolated-dexes");
+        File optimizedDir;
+
+        if (mIsPrimaryProcess) {
+            ensureAppFilesSubDirExists();
+            // Allows isolated processes to access the same files.
+            incrementalDexesDir.mkdir();
+            incrementalDexesDir.setReadable(true, false);
+            incrementalDexesDir.setExecutable(true, false);
+            // Create a directory for isolated processes to create directories in.
+            isolatedDexesDir.mkdir();
+            isolatedDexesDir.setWritable(true, false);
+            isolatedDexesDir.setExecutable(true, false);
+
+            optimizedDir = incrementalDexesDir;
+        } else {
+            // There is a UID check of the directory in dalvik.system.DexFile():
+            // https://android.googlesource.com/platform/libcore/+/45e0260/dalvik/src/main/java/dalvik/system/DexFile.java#101
+            // Rather than have each isolated process run DexOpt though, we use
+            // symlinks within the directory to point at the browser process'
+            // optimized dex files.
+            optimizedDir = new File(isolatedDexesDir, "isolated-" + mProcessUid);
+            optimizedDir.mkdir();
+            // Always wipe it out and re-create for simplicity.
+            Log.i(TAG, "Creating dex file symlinks for isolated process");
+            for (File f : optimizedDir.listFiles()) {
+                f.delete();
+            }
+            for (File f : incrementalDexesDir.listFiles()) {
+                String to = "../../" + incrementalDexesDir.getName() + "/" + f.getName();
+                File from = new File(optimizedDir, f.getName());
+                createSymlink(to, from);
+            }
+        }
+
+        Log.i(TAG, "Code cache dir: " + optimizedDir);
+        // TODO(agrieve): Might need to record classpath ordering if we ever have duplicate
+        //     class names (since then order will matter here).
+        Log.i(TAG, "Loading " + dexFilesArr.length + " dex files");
+
+        Object dexPathList = Reflect.getField(mClassLoader, "pathList");
+        Object[] dexElements = (Object[]) Reflect.getField(dexPathList, "dexElements");
+        Object[] additionalElements = makeDexElements(dexFilesArr, optimizedDir);
+        Reflect.setField(
+                dexPathList, "dexElements", Reflect.concatArrays(dexElements, additionalElements));
+    }
+
+    /**
+     * Sets up all libraries within |libDir| to be loadable by System.loadLibrary().
+     */
+    void importNativeLibs(File libDir) throws ReflectiveOperationException, IOException {
+        Log.i(TAG, "Importing native libraries from: " + libDir);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+            libDir = prepareNativeLibsAndroidM(libDir);
+        }
+        addNativeLibrarySearchPath(libDir);
+    }
+
+    /**
+     * Primary process: Copies native libraries into the app's data directory
+     * Other processes: Waits for primary process to finish copying.
+     */
+    private File prepareNativeLibsAndroidM(File libDir) throws IOException {
+        File localLibsDir = new File(mAppFilesSubDir, "lib");
+        File copyLibsLockFile = new File(mAppFilesSubDir, "libcopy.lock");
+        // Due to a new SELinux policy, all libs must be copied into the app's
+        // data directory first.
+        // https://code.google.com/p/android/issues/detail?id=79480
+        if (mIsPrimaryProcess) {
+            LockFile lockFile = LockFile.acquireRuntimeLock(copyLibsLockFile);
+            if (lockFile == null) {
+                LockFile.waitForRuntimeLock(copyLibsLockFile, 10 * 1000);
+            } else {
+                try {
+                    ensureAppFilesSubDirExists();
+                    localLibsDir.mkdir();
+                    localLibsDir.setReadable(true, false);
+                    localLibsDir.setExecutable(true, false);
+                    copyChangedFiles(libDir, localLibsDir);
+                } finally {
+                    lockFile.release();
+                }
+            }
+        } else {
+            // TODO: Work around this issue by using APK splits to install each dex / lib.
+            throw new RuntimeException("Incremental install does not work on Android M+ "
+                    + "with isolated processes. Use the gn arg:\n"
+                    + "    disable_incremental_isolated_processes=true\n"
+                    + "and try again.");
+        }
+        return localLibsDir;
+    }
+
+    @SuppressWarnings("unchecked")
+    private void addNativeLibrarySearchPath(File nativeLibDir) throws ReflectiveOperationException {
+        Object dexPathList = Reflect.getField(mClassLoader, "pathList");
+        Object currentDirs = Reflect.getField(dexPathList, "nativeLibraryDirectories");
+        File[] newDirs = new File[] { nativeLibDir };
+        // Switched from an array to an ArrayList in Lollipop.
+        if (currentDirs instanceof List) {
+            List<File> dirsAsList = (List<File>) currentDirs;
+            dirsAsList.add(nativeLibDir);
+        } else {
+            File[] dirsAsArray = (File[]) currentDirs;
+            Reflect.setField(dexPathList, "nativeLibraryDirectories",
+                    Reflect.concatArrays(dirsAsArray, newDirs));
+        }
+
+        Object[] nativeLibraryPathElements;
+        try {
+            nativeLibraryPathElements =
+                    (Object[]) Reflect.getField(dexPathList, "nativeLibraryPathElements");
+        } catch (NoSuchFieldException e) {
+            // This field doesn't exist pre-M.
+            return;
+        }
+        Object[] additionalElements = makeNativePathElements(newDirs);
+        Reflect.setField(
+                dexPathList, "nativeLibraryPathElements",
+                Reflect.concatArrays(nativeLibraryPathElements, additionalElements));
+    }
+
+    private static void copyChangedFiles(File srcDir, File dstDir) throws IOException {
+        // No need to delete stale libs since libraries are loaded explicitly.
+        for (File f : srcDir.listFiles()) {
+            // Note: Tried using hardlinks, but resulted in EACCES exceptions.
+            File dest = new File(dstDir, f.getName());
+            copyIfModified(f, dest);
+        }
+    }
+
+    private static void copyIfModified(File src, File dest) throws IOException {
+        long lastModified = src.lastModified();
+        if (!dest.exists() || dest.lastModified() != lastModified) {
+            Log.i(TAG, "Copying " + src + " -> " + dest);
+            FileInputStream istream = new FileInputStream(src);
+            FileOutputStream ostream = new FileOutputStream(dest);
+            ostream.getChannel().transferFrom(istream.getChannel(), 0, istream.getChannel().size());
+            istream.close();
+            ostream.close();
+            dest.setReadable(true, false);
+            dest.setExecutable(true,  false);
+            dest.setLastModified(lastModified);
+        }
+    }
+
+    private void ensureAppFilesSubDirExists() {
+        mAppFilesSubDir.mkdir();
+        mAppFilesSubDir.setExecutable(true, false);
+    }
+
+    private void createSymlink(String to, File from) throws ReflectiveOperationException {
+        Reflect.invokeMethod(mLibcoreOs, "symlink", to, from.getAbsolutePath());
+    }
+
+    private static Object[] makeNativePathElements(File[] paths)
+            throws ReflectiveOperationException {
+        Class<?> entryClazz = Class.forName("dalvik.system.DexPathList$Element");
+        Object[] entries = new Object[paths.length];
+        for (int i = 0; i < paths.length; ++i) {
+            entries[i] = Reflect.newInstance(entryClazz, paths[i], true, null, null);
+        }
+        return entries;
+    }
+
+    private static Object[] makeDexElements(File[] files, File optimizedDirectory)
+            throws ReflectiveOperationException {
+        Class<?> entryClazz = Class.forName("dalvik.system.DexPathList$Element");
+        Class<?> clazz = Class.forName("dalvik.system.DexPathList");
+        Object[] entries = new Object[files.length];
+        File emptyDir = new File("");
+        for (int i = 0; i < files.length; ++i) {
+            File file = files[i];
+            Object dexFile = Reflect.invokeMethod(clazz, "loadDexFile", file, optimizedDirectory);
+            entries[i] = Reflect.newInstance(entryClazz, emptyDir, false, file, dexFile);
+        }
+        return entries;
+    }
+}