/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.app;

import android.os.FileUtils;
import android.os.RemoteException;
import android.os.SystemProperties;
import android.util.Slog;

import com.android.internal.annotations.GuardedBy;

import dalvik.system.BaseDexClassLoader;
import dalvik.system.VMRuntime;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

A dex load reporter which will notify package manager of any dex file loaded with BaseDexClassLoader. The goals are: 1) discover secondary dex files so that they can be optimized during the idle maintenance job. 2) determine whether or not a dex file is used by an app which does not own it (in order to select the optimal compilation method). 
@hide
/**
 * A dex load reporter which will notify package manager of any dex file loaded
 * with {@code BaseDexClassLoader}.
 * The goals are:
 *     1) discover secondary dex files so that they can be optimized during the
 *        idle maintenance job.
 *     2) determine whether or not a dex file is used by an app which does not
 *        own it (in order to select the optimal compilation method).
 * @hide
 */
/*package*/ class DexLoadReporter implements BaseDexClassLoader.Reporter {
    private static final String TAG = "DexLoadReporter";

    private static final DexLoadReporter INSTANCE = new DexLoadReporter();

    private static final boolean DEBUG = false;

    // We must guard the access to the list of data directories because
    // we might have concurrent accesses. Apps might load dex files while
    // new data dirs are registered (due to creation of LoadedApks via
    // create createApplicationContext).
    @GuardedBy("mDataDirs")
    private final Set<String> mDataDirs;

    private DexLoadReporter() {
        mDataDirs = new HashSet<>();
    }

    /*package*/ static DexLoadReporter getInstance() {
        return INSTANCE;
    }

    
Register an application data directory with the reporter. The data directories are used to determine if a dex file is secondary dex or not. Note that this method may be called multiple times for the same app, registering different data directories. This may happen when apps share the same user id (android:sharedUserId). For example, if app1 and app2 share the same user id, and app1 loads app2 apk, then both data directories will be registered. /**
     * Register an application data directory with the reporter.
     * The data directories are used to determine if a dex file is secondary dex or not.
     * Note that this method may be called multiple times for the same app, registering
     * different data directories. This may happen when apps share the same user id
     * ({@code android:sharedUserId}). For example, if app1 and app2 share the same user
     * id, and app1 loads app2 apk, then both data directories will be registered.
     */
    /*package*/ void registerAppDataDir(String packageName, String dataDir) {
        if (DEBUG) {
            Slog.i(TAG, "Package " + packageName + " registering data dir: " + dataDir);
        }
        // TODO(calin): A few code paths imply that the data dir
        // might be null. Investigate when that can happen.
        if (dataDir != null) {
            synchronized (mDataDirs) {
                mDataDirs.add(dataDir);
            }
        }
    }

    @Override
    public void report(List<BaseDexClassLoader> classLoadersChain, List<String> classPaths) {
        if (classLoadersChain.size() != classPaths.size()) {
            Slog.wtf(TAG, "Bad call to DexLoadReporter: argument size mismatch");
            return;
        }
        if (classPaths.isEmpty()) {
            Slog.wtf(TAG, "Bad call to DexLoadReporter: empty dex paths");
            return;
        }

        // The first element of classPaths is the list of dex files that should be registered.
        // The classpath is represented as a list of dex files separated by File.pathSeparator.
        String[] dexPathsForRegistration = classPaths.get(0).split(File.pathSeparator);
        if (dexPathsForRegistration.length == 0) {
            // No dex files to register.
            return;
        }

        // Notify the package manager about the dex loads unconditionally.
        // The load might be for either a primary or secondary dex file.
        notifyPackageManager(classLoadersChain, classPaths);
        // Check for secondary dex files and register them for profiling if possible.
        // Note that we only register the dex paths belonging to the first class loader.
        registerSecondaryDexForProfiling(dexPathsForRegistration);
    }

    private void notifyPackageManager(List<BaseDexClassLoader> classLoadersChain,
            List<String> classPaths) {
        // Get the class loader names for the binder call.
        List<String> classLoadersNames = new ArrayList<>(classPaths.size());
        for (BaseDexClassLoader bdc : classLoadersChain) {
            classLoadersNames.add(bdc.getClass().getName());
        }
        String packageName = ActivityThread.currentPackageName();
        try {
            ActivityThread.getPackageManager().notifyDexLoad(
                    packageName, classLoadersNames, classPaths,
                    VMRuntime.getRuntime().vmInstructionSet());
        } catch (RemoteException re) {
            Slog.e(TAG, "Failed to notify PM about dex load for package " + packageName, re);
        }
    }

    private void registerSecondaryDexForProfiling(String[] dexPaths) {
        if (!SystemProperties.getBoolean("dalvik.vm.dexopt.secondary", false)) {
            return;
        }
        // Make a copy of the current data directories so that we don't keep the lock
        // while registering for profiling. The registration will perform I/O to
        // check for or create the profile.
        String[] dataDirs;
        synchronized (mDataDirs) {
            dataDirs = mDataDirs.toArray(new String[0]);
        }
        for (String dexPath : dexPaths) {
            registerSecondaryDexForProfiling(dexPath, dataDirs);
        }
    }

    private void registerSecondaryDexForProfiling(String dexPath, String[] dataDirs) {
        if (!isSecondaryDexFile(dexPath, dataDirs)) {
            // The dex path is not a secondary dex file. Nothing to do.
            return;
        }

        // Secondary dex profiles are stored in the oat directory, next to dex file
        // and have the same name with 'cur.prof' appended.
        // NOTE: Keep this in sync with installd expectations.
        File dexPathFile = new File(dexPath);
        File secondaryProfileDir = new File(dexPathFile.getParent(), "oat");
        File secondaryProfile = new File(secondaryProfileDir, dexPathFile.getName() + ".cur.prof");

        // Create the profile if not already there.
        // Returns true if the file was created, false if the file already exists.
        // or throws exceptions in case of errors.
        if (!secondaryProfileDir.exists()) {
            if (!secondaryProfileDir.mkdir()) {
                Slog.e(TAG, "Could not create the profile directory: " + secondaryProfile);
                // Do not continue with registration if we could not create the oat dir.
                return;
            }
        }

        try {
            boolean created = secondaryProfile.createNewFile();
            if (DEBUG && created) {
                Slog.i(TAG, "Created profile for secondary dex: " + secondaryProfile);
            }
        } catch (IOException ex) {
            Slog.e(TAG, "Failed to create profile for secondary dex " + dexPath
                    + ":" + ex.getMessage());
            // Do not continue with registration if we could not create the profile files.
            return;
        }

        // If we got here, the dex paths is a secondary dex and we were able to create the profile.
        // Register the path to the runtime.
        VMRuntime.registerAppInfo(secondaryProfile.getPath(), new String[] { dexPath });
    }

    // A dex file is a secondary dex file if it is in any of the registered app
    // data directories.
    private boolean isSecondaryDexFile(String dexPath, String[] dataDirs) {
        for (String dataDir : dataDirs) {
            if (FileUtils.contains(dataDir, dexPath)) {
                return true;
            }
        }
        return false;
    }
}