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      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 
     17 package android.app.backup;
     18 
     19 import android.os.ParcelFileDescriptor;
     20 import android.util.Log;
     21 
     22 import java.io.FileDescriptor;
     23 import java.io.IOException;
     24 import java.util.Map;
     25 import java.util.TreeMap;
     26 
     27 /** @hide */
     28 public 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