BackupHelperDispatcher.java revision 43a4a8c777fbb8f71540ac7fbe82674489ef557b
1/* 2 * Copyright (C) 2009 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 17package android.app.backup; 18 19import android.os.ParcelFileDescriptor; 20import android.util.Log; 21 22import java.io.FileDescriptor; 23import java.io.IOException; 24import java.util.Map; 25import java.util.TreeMap; 26 27/** @hide */ 28public class BackupHelperDispatcher { 29 private static final String TAG = "BackupHelperDispatcher"; 30 31 private static class Header { 32 int chunkSize; // not including the header 33 String keyPrefix; 34 } 35 36 TreeMap<String,BackupHelper> mHelpers = new TreeMap<String,BackupHelper>(); 37 38 public BackupHelperDispatcher() { 39 } 40 41 public void addHelper(String keyPrefix, BackupHelper helper) { 42 mHelpers.put(keyPrefix, helper); 43 } 44 45 public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, 46 ParcelFileDescriptor newState) throws IOException { 47 // First, do the helpers that we've already done, since they're already in the state 48 // file. 49 int err; 50 Header header = new Header(); 51 TreeMap<String,BackupHelper> helpers = (TreeMap<String,BackupHelper>)mHelpers.clone(); 52 FileDescriptor oldStateFD = null; 53 54 if (oldState != null) { 55 oldStateFD = oldState.getFileDescriptor(); 56 while ((err = readHeader_native(header, oldStateFD)) >= 0) { 57 if (err == 0) { 58 BackupHelper helper = helpers.get(header.keyPrefix); 59 Log.d(TAG, "handling existing helper '" + header.keyPrefix + "' " + helper); 60 if (helper != null) { 61 doOneBackup(oldState, data, newState, header, helper); 62 helpers.remove(header.keyPrefix); 63 } else { 64 skipChunk_native(oldStateFD, header.chunkSize); 65 } 66 } 67 } 68 } 69 70 // Then go through and do the rest that we haven't done. 71 for (Map.Entry<String,BackupHelper> entry: helpers.entrySet()) { 72 header.keyPrefix = entry.getKey(); 73 Log.d(TAG, "handling new helper '" + header.keyPrefix + "'"); 74 BackupHelper helper = entry.getValue(); 75 doOneBackup(oldState, data, newState, header, helper); 76 } 77 } 78 79 private void doOneBackup(ParcelFileDescriptor oldState, BackupDataOutput data, 80 ParcelFileDescriptor newState, Header header, BackupHelper helper) 81 throws IOException { 82 int err; 83 FileDescriptor newStateFD = newState.getFileDescriptor(); 84 85 // allocate space for the header in the file 86 int pos = allocateHeader_native(header, newStateFD); 87 if (pos < 0) { 88 throw new IOException("allocateHeader_native failed (error " + pos + ")"); 89 } 90 91 data.setKeyPrefix(header.keyPrefix); 92 93 // do the backup 94 helper.performBackup(oldState, data, newState); 95 96 // fill in the header (seeking back to pos). The file pointer will be returned to 97 // where it was at the end of performBackup. Header.chunkSize will not be filled in. 98 err = writeHeader_native(header, newStateFD, pos); 99 if (err != 0) { 100 throw new IOException("writeHeader_native failed (error " + err + ")"); 101 } 102 } 103 104 public void performRestore(BackupDataInput input, int appVersionCode, 105 ParcelFileDescriptor newState) 106 throws IOException { 107 boolean alreadyComplained = false; 108 109 BackupDataInputStream stream = new BackupDataInputStream(input); 110 while (input.readNextHeader()) { 111 112 String rawKey = input.getKey(); 113 int pos = rawKey.indexOf(':'); 114 if (pos > 0) { 115 String prefix = rawKey.substring(0, pos); 116 BackupHelper helper = mHelpers.get(prefix); 117 if (helper != null) { 118 stream.dataSize = input.getDataSize(); 119 stream.key = rawKey.substring(pos+1); 120 helper.restoreEntity(stream); 121 } else { 122 if (!alreadyComplained) { 123 Log.w(TAG, "Couldn't find helper for: '" + rawKey + "'"); 124 alreadyComplained = true; 125 } 126 } 127 } else { 128 if (!alreadyComplained) { 129 Log.w(TAG, "Entity with no prefix: '" + rawKey + "'"); 130 alreadyComplained = true; 131 } 132 } 133 input.skipEntityData(); // In case they didn't consume the data. 134 } 135 136 // Write out the state files -- mHelpers is a TreeMap, so the order is well defined. 137 for (BackupHelper helper: mHelpers.values()) { 138 helper.writeNewStateDescription(newState); 139 } 140 } 141 142 private static native int readHeader_native(Header h, FileDescriptor fd); 143 private static native int skipChunk_native(FileDescriptor fd, int bytesToSkip); 144 145 private static native int allocateHeader_native(Header h, FileDescriptor fd); 146 private static native int writeHeader_native(Header h, FileDescriptor fd, int pos); 147} 148 149