1 /**
2  * Copyright (C) 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.settings.backup;
18 
19 import android.app.backup.BackupAgentHelper;
20 import android.app.backup.BackupDataInputStream;
21 import android.app.backup.BackupDataOutput;
22 import android.app.backup.BackupHelper;
23 import android.os.ParcelFileDescriptor;
24 
25 import com.android.settings.shortcut.CreateShortcutPreferenceController;
26 
27 import java.io.FileInputStream;
28 import java.io.FileOutputStream;
29 import java.io.IOException;
30 
31 /**
32  * Backup agent for Settings APK
33  */
34 public class SettingsBackupHelper extends BackupAgentHelper {
35 
36     @Override
onCreate()37     public void onCreate() {
38         super.onCreate();
39         addHelper("no-op", new NoOpHelper());
40     }
41 
42     @Override
onRestoreFinished()43     public void onRestoreFinished() {
44         super.onRestoreFinished();
45         CreateShortcutPreferenceController.updateRestoredShortcuts(this);
46     }
47 
48     /**
49      * Backup helper which does not do anything. Having at least one helper ensures that the
50      * transport is not empty and onRestoreFinished is called eventually.
51      */
52     private static class NoOpHelper implements BackupHelper {
53 
54         private final int VERSION_CODE = 1;
55 
56         @Override
performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState)57         public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
58                 ParcelFileDescriptor newState) {
59 
60             try (FileOutputStream out = new FileOutputStream(newState.getFileDescriptor())) {
61                 if (getVersionCode(oldState) != VERSION_CODE) {
62                     data.writeEntityHeader("dummy", 1);
63                     data.writeEntityData(new byte[1], 1);
64                 }
65 
66                 // Write new version code
67                 out.write(VERSION_CODE);
68                 out.flush();
69             } catch (IOException e) { }
70         }
71 
72         @Override
restoreEntity(BackupDataInputStream data)73         public void restoreEntity(BackupDataInputStream data) { }
74 
75         @Override
writeNewStateDescription(ParcelFileDescriptor newState)76         public void writeNewStateDescription(ParcelFileDescriptor newState) { }
77 
getVersionCode(ParcelFileDescriptor state)78         private int getVersionCode(ParcelFileDescriptor state) {
79             if (state == null) {
80                 return 0;
81             }
82             try (FileInputStream in = new FileInputStream(state.getFileDescriptor())) {
83                 return in.read();
84             } catch (IOException e) {
85                 return 0;
86             }
87         }
88     }
89 }
90