packages/WallpaperBackup/src/com/android/wallpaperbackup/WallpaperBackupAgent.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2016 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 com.android.wallpaperbackup;

 import static android.app.WallpaperManager.FLAG_LOCK;
 import static android.app.WallpaperManager.FLAG_SYSTEM;

 import android.app.AppGlobals;
 import android.app.WallpaperManager;
 import android.app.backup.BackupAgent;
 import android.app.backup.BackupDataInput;
 import android.app.backup.BackupDataOutput;
 import android.app.backup.FullBackupDataOutput;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.pm.IPackageManager;
 import android.content.pm.PackageInfo;
 import android.graphics.Rect;
 import android.os.Environment;
 import android.os.FileUtils;
 import android.os.ParcelFileDescriptor;
 import android.os.RemoteException;
 import android.os.UserHandle;
 import android.util.Slog;
 import android.util.Xml;

 import libcore.io.IoUtils;

 import org.xmlpull.v1.XmlPullParser;

 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;

 public class WallpaperBackupAgent extends BackupAgent {
     private static final String TAG = "WallpaperBackup";
     private static final boolean DEBUG = false;

     // NB: must be kept in sync with WallpaperManagerService but has no
     // compile-time visibility.

     // Target filenames within the system's wallpaper directory
     static final String WALLPAPER = "wallpaper_orig";
     static final String WALLPAPER_LOCK = "wallpaper_lock_orig";
     static final String WALLPAPER_INFO = "wallpaper_info.xml";

     // Names of our local-data stage files/links
     static final String IMAGE_STAGE = "wallpaper-stage";
     static final String LOCK_IMAGE_STAGE = "wallpaper-lock-stage";
     static final String INFO_STAGE = "wallpaper-info-stage";
     static final String EMPTY_SENTINEL = "empty";
     static final String QUOTA_SENTINEL = "quota";

     // Not-for-backup bookkeeping
     static final String PREFS_NAME = "wbprefs.xml";
     static final String SYSTEM_GENERATION = "system_gen";
     static final String LOCK_GENERATION = "lock_gen";

     private File mWallpaperInfo;        // wallpaper metadata file
     private File mWallpaperFile;        // primary wallpaper image file
     private File mLockWallpaperFile;    // lock wallpaper image file

     // If this file exists, it means we exceeded our quota last time
     private File mQuotaFile;
     private boolean mQuotaExceeded;

     private WallpaperManager mWm;

     @Override
     public void onCreate() {
         if (DEBUG) {
             Slog.v(TAG, "onCreate()");
         }

         File wallpaperDir = Environment.getUserSystemDirectory(UserHandle.USER_SYSTEM);
         mWallpaperInfo = new File(wallpaperDir, WALLPAPER_INFO);
         mWallpaperFile = new File(wallpaperDir, WALLPAPER);
         mLockWallpaperFile = new File(wallpaperDir, WALLPAPER_LOCK);
         mWm = (WallpaperManager) getSystemService(Context.WALLPAPER_SERVICE);

         mQuotaFile = new File(getFilesDir(), QUOTA_SENTINEL);
         mQuotaExceeded = mQuotaFile.exists();
         if (DEBUG) {
             Slog.v(TAG, "quota file " + mQuotaFile.getPath() + " exists=" + mQuotaExceeded);
         }
     }

     @Override
     public void onFullBackup(FullBackupDataOutput data) throws IOException {
         // To avoid data duplication and disk churn, use links as the stage.
         final File filesDir = getFilesDir();
         final File infoStage = new File(filesDir, INFO_STAGE);
         final File imageStage = new File (filesDir, IMAGE_STAGE);
         final File lockImageStage = new File (filesDir, LOCK_IMAGE_STAGE);
         final File empty = new File (filesDir, EMPTY_SENTINEL);

         try {
             // We always back up this 'empty' file to ensure that the absence of
             // storable wallpaper imagery still produces a non-empty backup data
             // stream, otherwise it'd simply be ignored in preflight.
             FileOutputStream touch = new FileOutputStream(empty);
             touch.close();
             fullBackupFile(empty, data);

             SharedPreferences prefs = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
             final int lastSysGeneration = prefs.getInt(SYSTEM_GENERATION, -1);
             final int lastLockGeneration = prefs.getInt(LOCK_GENERATION, -1);

             final int sysGeneration =
                     mWm.getWallpaperIdForUser(FLAG_SYSTEM, UserHandle.USER_SYSTEM);
             final int lockGeneration =
                     mWm.getWallpaperIdForUser(FLAG_LOCK, UserHandle.USER_SYSTEM);
             final boolean sysChanged = (sysGeneration != lastSysGeneration);
             final boolean lockChanged = (lockGeneration != lastLockGeneration);

             final boolean sysEligible = mWm.isWallpaperBackupEligible(FLAG_SYSTEM);
             final boolean lockEligible = mWm.isWallpaperBackupEligible(FLAG_LOCK);

                 // There might be a latent lock wallpaper file present but unused: don't
                 // include it in the backup if that's the case.
                 ParcelFileDescriptor lockFd = mWm.getWallpaperFile(FLAG_LOCK, UserHandle.USER_SYSTEM);
                 final boolean hasLockWallpaper = (lockFd != null);
                 IoUtils.closeQuietly(lockFd);

             if (DEBUG) {
                 Slog.v(TAG, "sysGen=" + sysGeneration + " : sysChanged=" + sysChanged);
                 Slog.v(TAG, "lockGen=" + lockGeneration + " : lockChanged=" + lockChanged);
                 Slog.v(TAG, "sysEligble=" + sysEligible);
                 Slog.v(TAG, "lockEligible=" + lockEligible);
             }

             // only back up the wallpapers if we've been told they're eligible
             if (mWallpaperInfo.exists()) {
                 if (sysChanged || lockChanged || !infoStage.exists()) {
                     if (DEBUG) Slog.v(TAG, "New wallpaper configuration; copying");
                     FileUtils.copyFileOrThrow(mWallpaperInfo, infoStage);
                 }
                 if (DEBUG) Slog.v(TAG, "Storing wallpaper metadata");
                 fullBackupFile(infoStage, data);
             }
             if (sysEligible && mWallpaperFile.exists()) {
                 if (sysChanged || !imageStage.exists()) {
                     if (DEBUG) Slog.v(TAG, "New system wallpaper; copying");
                     FileUtils.copyFileOrThrow(mWallpaperFile, imageStage);
                 }
                 if (DEBUG) Slog.v(TAG, "Storing system wallpaper image");
                 fullBackupFile(imageStage, data);
                 prefs.edit().putInt(SYSTEM_GENERATION, sysGeneration).apply();
             }

             // Don't try to store the lock image if we overran our quota last time
             if (lockEligible && hasLockWallpaper && mLockWallpaperFile.exists() && !mQuotaExceeded) {
                 if (lockChanged || !lockImageStage.exists()) {
                     if (DEBUG) Slog.v(TAG, "New lock wallpaper; copying");
                     FileUtils.copyFileOrThrow(mLockWallpaperFile, lockImageStage);
                 }
                 if (DEBUG) Slog.v(TAG, "Storing lock wallpaper image");
                 fullBackupFile(lockImageStage, data);
                 prefs.edit().putInt(LOCK_GENERATION, lockGeneration).apply();
             }
         } catch (Exception e) {
             Slog.e(TAG, "Unable to back up wallpaper", e);
         } finally {
             // Even if this time we had to back off on attempting to store the lock image
             // due to exceeding the data quota, try again next time.  This will alternate
             // between "try both" and "only store the primary image" until either there
             // is no lock image to store, or the quota is raised, or both fit under the
             // quota.
             mQuotaFile.delete();
         }
     }

     @Override
     public void onQuotaExceeded(long backupDataBytes, long quotaBytes) {
         if (DEBUG) {
             Slog.i(TAG, "Quota exceeded (" + backupDataBytes + " vs " + quotaBytes + ')');
         }
         try (FileOutputStream f = new FileOutputStream(mQuotaFile)) {
             f.write(0);
         } catch (Exception e) {
             Slog.w(TAG, "Unable to record quota-exceeded: " + e.getMessage());
         }
     }

     // We use the default onRestoreFile() implementation that will recreate our stage files,
     // then post-process in onRestoreFinished() to apply the new wallpaper.
     @Override
     public void onRestoreFinished() {
         if (DEBUG) {
             Slog.v(TAG, "onRestoreFinished()");
         }
         final File filesDir = getFilesDir();
         final File infoStage = new File(filesDir, INFO_STAGE);
         final File imageStage = new File (filesDir, IMAGE_STAGE);
         final File lockImageStage = new File (filesDir, LOCK_IMAGE_STAGE);

         // If we restored separate lock imagery, the system wallpaper should be
         // applied as system-only; but if there's no separate lock image, make
         // sure to apply the restored system wallpaper as both.
         final int sysWhich = FLAG_SYSTEM | (lockImageStage.exists() ? 0 : FLAG_LOCK);

         try {
             // It is valid for the imagery to be absent; it means that we were not permitted
             // to back up the original image on the source device, or there was no user-supplied
             // wallpaper image present.
             restoreFromStage(imageStage, infoStage, "wp", sysWhich);
             restoreFromStage(lockImageStage, infoStage, "kwp", FLAG_LOCK);

             // And reset to the wallpaper service we should be using
             ComponentName wpService = parseWallpaperComponent(infoStage, "wp");
             if (servicePackageExists(wpService)) {
                 if (DEBUG) {
                     Slog.i(TAG, "Using wallpaper service " + wpService);
                 }
                 mWm.setWallpaperComponent(wpService, UserHandle.USER_SYSTEM);
                 if (!lockImageStage.exists()) {
                     // We have a live wallpaper and no static lock image,
                     // allow live wallpaper to show "through" on lock screen.
                     mWm.clear(FLAG_LOCK);
                 }
             } else {
                 if (DEBUG) {
                     Slog.v(TAG, "Can't use wallpaper service " + wpService);
                 }
             }
         } catch (Exception e) {
             Slog.e(TAG, "Unable to restore wallpaper: " + e.getMessage());
         } finally {
             if (DEBUG) {
                 Slog.v(TAG, "Restore finished; clearing backup bookkeeping");
             }
             infoStage.delete();
             imageStage.delete();
             lockImageStage.delete();

             SharedPreferences prefs = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
             prefs.edit()
                     .putInt(SYSTEM_GENERATION, -1)
                     .putInt(LOCK_GENERATION, -1)
                     .commit();
         }
     }

     private void restoreFromStage(File stage, File info, String hintTag, int which)
             throws IOException {
         if (stage.exists()) {
             // Parse the restored info file to find the crop hint.  Note that this currently
             // relies on a priori knowledge of the wallpaper info file schema.
             Rect cropHint = parseCropHint(info, hintTag);
             if (cropHint != null) {
                 Slog.i(TAG, "Got restored wallpaper; applying which=" + which);
                 if (DEBUG) {
                     Slog.v(TAG, "Restored crop hint " + cropHint);
                 }
                 try (FileInputStream in = new FileInputStream(stage)) {
                     mWm.setStream(in, cropHint.isEmpty() ? null : cropHint, true, which);
                 } finally {} // auto-closes 'in'
             }
         }
     }

     private Rect parseCropHint(File wallpaperInfo, String sectionTag) {
         Rect cropHint = new Rect();
         try (FileInputStream stream = new FileInputStream(wallpaperInfo)) {
             XmlPullParser parser = Xml.newPullParser();
             parser.setInput(stream, StandardCharsets.UTF_8.name());

             int type;
             do {
                 type = parser.next();
                 if (type == XmlPullParser.START_TAG) {
                     String tag = parser.getName();
                     if (sectionTag.equals(tag)) {
                         cropHint.left = getAttributeInt(parser, "cropLeft", 0);
                         cropHint.top = getAttributeInt(parser, "cropTop", 0);
                         cropHint.right = getAttributeInt(parser, "cropRight", 0);
                         cropHint.bottom = getAttributeInt(parser, "cropBottom", 0);
                     }
                 }
             } while (type != XmlPullParser.END_DOCUMENT);
         } catch (Exception e) {
             // Whoops; can't process the info file at all.  Report failure.
             Slog.w(TAG, "Failed to parse restored crop: " + e.getMessage());
             return null;
         }

         return cropHint;
     }

     private ComponentName parseWallpaperComponent(File wallpaperInfo, String sectionTag) {
         ComponentName name = null;
         try (FileInputStream stream = new FileInputStream(wallpaperInfo)) {
             final XmlPullParser parser = Xml.newPullParser();
             parser.setInput(stream, StandardCharsets.UTF_8.name());

             int type;
             do {
                 type = parser.next();
                 if (type == XmlPullParser.START_TAG) {
                     String tag = parser.getName();
                     if (sectionTag.equals(tag)) {
                         final String parsedName = parser.getAttributeValue(null, "component");
                         name = (parsedName != null)
                                 ? ComponentName.unflattenFromString(parsedName)
                                 : null;
                         break;
                     }
                 }
             } while (type != XmlPullParser.END_DOCUMENT);
         } catch (Exception e) {
             // Whoops; can't process the info file at all.  Report failure.
             Slog.w(TAG, "Failed to parse restored component: " + e.getMessage());
             return null;
         }
         return name;
     }

     private int getAttributeInt(XmlPullParser parser, String name, int defValue) {
         final String value = parser.getAttributeValue(null, name);
         return (value == null) ? defValue : Integer.parseInt(value);
     }

     private boolean servicePackageExists(ComponentName comp) {
         try {
             if (comp != null) {
                 final IPackageManager pm = AppGlobals.getPackageManager();
                 final PackageInfo info = pm.getPackageInfo(comp.getPackageName(),
                         0, UserHandle.USER_SYSTEM);
                 return (info != null);
             }
         } catch (RemoteException e) {
             Slog.e(TAG, "Unable to contact package manager");
         }
         return false;
     }

     //
     // Key/value API: abstract, therefore required; but not used
     //

     @Override
     public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
             ParcelFileDescriptor newState) throws IOException {
         // Intentionally blank
     }

     @Override
     public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState)
             throws IOException {
         // Intentionally blank
     }
 }
	/*
	* Copyright (C) 2016 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 com.android.wallpaperbackup;

	import static android.app.WallpaperManager.FLAG_LOCK;
	import static android.app.WallpaperManager.FLAG_SYSTEM;

	import android.app.AppGlobals;
	import android.app.WallpaperManager;
	import android.app.backup.BackupAgent;
	import android.app.backup.BackupDataInput;
	import android.app.backup.BackupDataOutput;
	import android.app.backup.FullBackupDataOutput;
	import android.content.ComponentName;
	import android.content.Context;
	import android.content.SharedPreferences;
	import android.content.pm.IPackageManager;
	import android.content.pm.PackageInfo;
	import android.graphics.Rect;
	import android.os.Environment;
	import android.os.FileUtils;
	import android.os.ParcelFileDescriptor;
	import android.os.RemoteException;
	import android.os.UserHandle;
	import android.util.Slog;
	import android.util.Xml;

	import libcore.io.IoUtils;

	import org.xmlpull.v1.XmlPullParser;

	import java.io.File;
	import java.io.FileInputStream;
	import java.io.FileOutputStream;
	import java.io.IOException;
	import java.nio.charset.StandardCharsets;

	public class WallpaperBackupAgent extends BackupAgent {
	private static final String TAG = "WallpaperBackup";
	private static final boolean DEBUG = false;

	// NB: must be kept in sync with WallpaperManagerService but has no
	// compile-time visibility.

	// Target filenames within the system's wallpaper directory
	static final String WALLPAPER = "wallpaper_orig";
	static final String WALLPAPER_LOCK = "wallpaper_lock_orig";
	static final String WALLPAPER_INFO = "wallpaper_info.xml";

	// Names of our local-data stage files/links
	static final String IMAGE_STAGE = "wallpaper-stage";
	static final String LOCK_IMAGE_STAGE = "wallpaper-lock-stage";
	static final String INFO_STAGE = "wallpaper-info-stage";
	static final String EMPTY_SENTINEL = "empty";
	static final String QUOTA_SENTINEL = "quota";

	// Not-for-backup bookkeeping
	static final String PREFS_NAME = "wbprefs.xml";
	static final String SYSTEM_GENERATION = "system_gen";
	static final String LOCK_GENERATION = "lock_gen";

	private File mWallpaperInfo; // wallpaper metadata file
	private File mWallpaperFile; // primary wallpaper image file
	private File mLockWallpaperFile; // lock wallpaper image file

	// If this file exists, it means we exceeded our quota last time
	private File mQuotaFile;
	private boolean mQuotaExceeded;

	private WallpaperManager mWm;

	@Override
	public void onCreate() {
	if (DEBUG) {
	Slog.v(TAG, "onCreate()");
	}

	File wallpaperDir = Environment.getUserSystemDirectory(UserHandle.USER_SYSTEM);
	mWallpaperInfo = new File(wallpaperDir, WALLPAPER_INFO);
	mWallpaperFile = new File(wallpaperDir, WALLPAPER);
	mLockWallpaperFile = new File(wallpaperDir, WALLPAPER_LOCK);
	mWm = (WallpaperManager) getSystemService(Context.WALLPAPER_SERVICE);

	mQuotaFile = new File(getFilesDir(), QUOTA_SENTINEL);
	mQuotaExceeded = mQuotaFile.exists();
	if (DEBUG) {
	Slog.v(TAG, "quota file " + mQuotaFile.getPath() + " exists=" + mQuotaExceeded);
	}
	}

	@Override
	public void onFullBackup(FullBackupDataOutput data) throws IOException {
	// To avoid data duplication and disk churn, use links as the stage.
	final File filesDir = getFilesDir();
	final File infoStage = new File(filesDir, INFO_STAGE);
	final File imageStage = new File (filesDir, IMAGE_STAGE);
	final File lockImageStage = new File (filesDir, LOCK_IMAGE_STAGE);
	final File empty = new File (filesDir, EMPTY_SENTINEL);

	try {
	// We always back up this 'empty' file to ensure that the absence of
	// storable wallpaper imagery still produces a non-empty backup data
	// stream, otherwise it'd simply be ignored in preflight.
	FileOutputStream touch = new FileOutputStream(empty);
	touch.close();
	fullBackupFile(empty, data);

	SharedPreferences prefs = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
	final int lastSysGeneration = prefs.getInt(SYSTEM_GENERATION, -1);
	final int lastLockGeneration = prefs.getInt(LOCK_GENERATION, -1);

	final int sysGeneration =
	mWm.getWallpaperIdForUser(FLAG_SYSTEM, UserHandle.USER_SYSTEM);
	final int lockGeneration =
	mWm.getWallpaperIdForUser(FLAG_LOCK, UserHandle.USER_SYSTEM);
	final boolean sysChanged = (sysGeneration != lastSysGeneration);
	final boolean lockChanged = (lockGeneration != lastLockGeneration);

	final boolean sysEligible = mWm.isWallpaperBackupEligible(FLAG_SYSTEM);
	final boolean lockEligible = mWm.isWallpaperBackupEligible(FLAG_LOCK);

	// There might be a latent lock wallpaper file present but unused: don't
	// include it in the backup if that's the case.
	ParcelFileDescriptor lockFd = mWm.getWallpaperFile(FLAG_LOCK, UserHandle.USER_SYSTEM);
	final boolean hasLockWallpaper = (lockFd != null);
	IoUtils.closeQuietly(lockFd);

	if (DEBUG) {
	Slog.v(TAG, "sysGen=" + sysGeneration + " : sysChanged=" + sysChanged);
	Slog.v(TAG, "lockGen=" + lockGeneration + " : lockChanged=" + lockChanged);
	Slog.v(TAG, "sysEligble=" + sysEligible);
	Slog.v(TAG, "lockEligible=" + lockEligible);
	}

	// only back up the wallpapers if we've been told they're eligible
	if (mWallpaperInfo.exists()) {
	if (sysChanged \|\| lockChanged \|\| !infoStage.exists()) {
	if (DEBUG) Slog.v(TAG, "New wallpaper configuration; copying");
	FileUtils.copyFileOrThrow(mWallpaperInfo, infoStage);
	}
	if (DEBUG) Slog.v(TAG, "Storing wallpaper metadata");
	fullBackupFile(infoStage, data);
	}
	if (sysEligible && mWallpaperFile.exists()) {
	if (sysChanged \|\| !imageStage.exists()) {
	if (DEBUG) Slog.v(TAG, "New system wallpaper; copying");
	FileUtils.copyFileOrThrow(mWallpaperFile, imageStage);
	}
	if (DEBUG) Slog.v(TAG, "Storing system wallpaper image");
	fullBackupFile(imageStage, data);
	prefs.edit().putInt(SYSTEM_GENERATION, sysGeneration).apply();
	}

	// Don't try to store the lock image if we overran our quota last time
	if (lockEligible && hasLockWallpaper && mLockWallpaperFile.exists() && !mQuotaExceeded) {
	if (lockChanged \|\| !lockImageStage.exists()) {
	if (DEBUG) Slog.v(TAG, "New lock wallpaper; copying");
	FileUtils.copyFileOrThrow(mLockWallpaperFile, lockImageStage);
	}
	if (DEBUG) Slog.v(TAG, "Storing lock wallpaper image");
	fullBackupFile(lockImageStage, data);
	prefs.edit().putInt(LOCK_GENERATION, lockGeneration).apply();
	}
	} catch (Exception e) {
	Slog.e(TAG, "Unable to back up wallpaper", e);
	} finally {
	// Even if this time we had to back off on attempting to store the lock image
	// due to exceeding the data quota, try again next time. This will alternate
	// between "try both" and "only store the primary image" until either there
	// is no lock image to store, or the quota is raised, or both fit under the
	// quota.
	mQuotaFile.delete();
	}
	}

	@Override
	public void onQuotaExceeded(long backupDataBytes, long quotaBytes) {
	if (DEBUG) {
	Slog.i(TAG, "Quota exceeded (" + backupDataBytes + " vs " + quotaBytes + ')');
	}
	try (FileOutputStream f = new FileOutputStream(mQuotaFile)) {
	f.write(0);
	} catch (Exception e) {
	Slog.w(TAG, "Unable to record quota-exceeded: " + e.getMessage());
	}
	}

	// We use the default onRestoreFile() implementation that will recreate our stage files,
	// then post-process in onRestoreFinished() to apply the new wallpaper.
	@Override
	public void onRestoreFinished() {
	if (DEBUG) {
	Slog.v(TAG, "onRestoreFinished()");
	}
	final File filesDir = getFilesDir();
	final File infoStage = new File(filesDir, INFO_STAGE);
	final File imageStage = new File (filesDir, IMAGE_STAGE);
	final File lockImageStage = new File (filesDir, LOCK_IMAGE_STAGE);

	// If we restored separate lock imagery, the system wallpaper should be
	// applied as system-only; but if there's no separate lock image, make
	// sure to apply the restored system wallpaper as both.
	final int sysWhich = FLAG_SYSTEM \| (lockImageStage.exists() ? 0 : FLAG_LOCK);

	try {
	// It is valid for the imagery to be absent; it means that we were not permitted
	// to back up the original image on the source device, or there was no user-supplied
	// wallpaper image present.
	restoreFromStage(imageStage, infoStage, "wp", sysWhich);
	restoreFromStage(lockImageStage, infoStage, "kwp", FLAG_LOCK);

	// And reset to the wallpaper service we should be using
	ComponentName wpService = parseWallpaperComponent(infoStage, "wp");
	if (servicePackageExists(wpService)) {
	if (DEBUG) {
	Slog.i(TAG, "Using wallpaper service " + wpService);
	}
	mWm.setWallpaperComponent(wpService, UserHandle.USER_SYSTEM);
	if (!lockImageStage.exists()) {
	// We have a live wallpaper and no static lock image,
	// allow live wallpaper to show "through" on lock screen.
	mWm.clear(FLAG_LOCK);
	}
	} else {
	if (DEBUG) {
	Slog.v(TAG, "Can't use wallpaper service " + wpService);
	}
	}
	} catch (Exception e) {
	Slog.e(TAG, "Unable to restore wallpaper: " + e.getMessage());
	} finally {
	if (DEBUG) {
	Slog.v(TAG, "Restore finished; clearing backup bookkeeping");
	}
	infoStage.delete();
	imageStage.delete();
	lockImageStage.delete();

	SharedPreferences prefs = getSharedPreferences(PREFS_NAME, Context.MODE_PRIVATE);
	prefs.edit()
	.putInt(SYSTEM_GENERATION, -1)
	.putInt(LOCK_GENERATION, -1)
	.commit();
	}
	}

	private void restoreFromStage(File stage, File info, String hintTag, int which)
	throws IOException {
	if (stage.exists()) {
	// Parse the restored info file to find the crop hint. Note that this currently
	// relies on a priori knowledge of the wallpaper info file schema.
	Rect cropHint = parseCropHint(info, hintTag);
	if (cropHint != null) {
	Slog.i(TAG, "Got restored wallpaper; applying which=" + which);
	if (DEBUG) {
	Slog.v(TAG, "Restored crop hint " + cropHint);
	}
	try (FileInputStream in = new FileInputStream(stage)) {
	mWm.setStream(in, cropHint.isEmpty() ? null : cropHint, true, which);
	} finally {} // auto-closes 'in'
	}
	}
	}

	private Rect parseCropHint(File wallpaperInfo, String sectionTag) {
	Rect cropHint = new Rect();
	try (FileInputStream stream = new FileInputStream(wallpaperInfo)) {
	XmlPullParser parser = Xml.newPullParser();
	parser.setInput(stream, StandardCharsets.UTF_8.name());

	int type;
	do {
	type = parser.next();
	if (type == XmlPullParser.START_TAG) {
	String tag = parser.getName();
	if (sectionTag.equals(tag)) {
	cropHint.left = getAttributeInt(parser, "cropLeft", 0);
	cropHint.top = getAttributeInt(parser, "cropTop", 0);
	cropHint.right = getAttributeInt(parser, "cropRight", 0);
	cropHint.bottom = getAttributeInt(parser, "cropBottom", 0);
	}
	}
	} while (type != XmlPullParser.END_DOCUMENT);
	} catch (Exception e) {
	// Whoops; can't process the info file at all. Report failure.
	Slog.w(TAG, "Failed to parse restored crop: " + e.getMessage());
	return null;
	}

	return cropHint;
	}

	private ComponentName parseWallpaperComponent(File wallpaperInfo, String sectionTag) {
	ComponentName name = null;
	try (FileInputStream stream = new FileInputStream(wallpaperInfo)) {
	final XmlPullParser parser = Xml.newPullParser();
	parser.setInput(stream, StandardCharsets.UTF_8.name());

	int type;
	do {
	type = parser.next();
	if (type == XmlPullParser.START_TAG) {
	String tag = parser.getName();
	if (sectionTag.equals(tag)) {
	final String parsedName = parser.getAttributeValue(null, "component");
	name = (parsedName != null)
	? ComponentName.unflattenFromString(parsedName)
	: null;
	break;
	}
	}
	} while (type != XmlPullParser.END_DOCUMENT);
	} catch (Exception e) {
	// Whoops; can't process the info file at all. Report failure.
	Slog.w(TAG, "Failed to parse restored component: " + e.getMessage());
	return null;
	}
	return name;
	}

	private int getAttributeInt(XmlPullParser parser, String name, int defValue) {
	final String value = parser.getAttributeValue(null, name);
	return (value == null) ? defValue : Integer.parseInt(value);
	}

	private boolean servicePackageExists(ComponentName comp) {
	try {
	if (comp != null) {
	final IPackageManager pm = AppGlobals.getPackageManager();
	final PackageInfo info = pm.getPackageInfo(comp.getPackageName(),
	0, UserHandle.USER_SYSTEM);
	return (info != null);
	}
	} catch (RemoteException e) {
	Slog.e(TAG, "Unable to contact package manager");
	}
	return false;
	}

	//
	// Key/value API: abstract, therefore required; but not used
	//

	@Override
	public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
	ParcelFileDescriptor newState) throws IOException {
	// Intentionally blank
	}

	@Override
	public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState)
	throws IOException {
	// Intentionally blank
	}
	}