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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         FileDescriptor newStateFD = newState.getFileDescriptor();
     54 
     55         if (oldState != null) {
     56             oldStateFD = oldState.getFileDescriptor();
     57             while ((err = readHeader_native(header, oldStateFD)) >= 0) {
     58                 if (err == 0) {
     59                     BackupHelper helper = helpers.get(header.keyPrefix);
     60                     Log.d(TAG, "handling existing helper '" + header.keyPrefix + "' " + helper);
     61                     if (helper != null) {
     62                         doOneBackup(oldState, data, newState, header, helper);
     63                         helpers.remove(header.keyPrefix);
     64                     } else {
     65                         skipChunk_native(oldStateFD, header.chunkSize);
     66                     }
     67                 }
     68             }
     69         }
     70 
     71         // Then go through and do the rest that we haven't done.
     72         for (Map.Entry<String,BackupHelper> entry: helpers.entrySet()) {
     73             header.keyPrefix = entry.getKey();
     74             Log.d(TAG, "handling new helper '" + header.keyPrefix + "'");
     75             BackupHelper helper = entry.getValue();
     76             doOneBackup(oldState, data, newState, header, helper);
     77         }
     78     }
     79 
     80     private void doOneBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
     81             ParcelFileDescriptor newState, Header header, BackupHelper helper)
     82             throws IOException {
     83         int err;
     84         FileDescriptor newStateFD = newState.getFileDescriptor();
     85 
     86         // allocate space for the header in the file
     87         int pos = allocateHeader_native(header, newStateFD);
     88         if (pos < 0) {
     89             throw new IOException("allocateHeader_native failed (error " + pos + ")");
     90         }
     91 
     92         data.setKeyPrefix(header.keyPrefix);
     93 
     94         // do the backup
     95         helper.performBackup(oldState, data, newState);
     96 
     97         // fill in the header (seeking back to pos).  The file pointer will be returned to
     98         // where it was at the end of performBackup.  Header.chunkSize will not be filled in.
     99         err = writeHeader_native(header, newStateFD, pos);
    100         if (err != 0) {
    101             throw new IOException("writeHeader_native failed (error " + err + ")");
    102         }
    103     }
    104 
    105     public void performRestore(BackupDataInput input, int appVersionCode,
    106             ParcelFileDescriptor newState)
    107             throws IOException {
    108         boolean alreadyComplained = false;
    109 
    110         BackupDataInputStream stream = new BackupDataInputStream(input);
    111         while (input.readNextHeader()) {
    112 
    113             String rawKey = input.getKey();
    114             int pos = rawKey.indexOf(':');
    115             if (pos > 0) {
    116                 String prefix = rawKey.substring(0, pos);
    117                 BackupHelper helper = mHelpers.get(prefix);
    118                 if (helper != null) {
    119                     stream.dataSize = input.getDataSize();
    120                     stream.key = rawKey.substring(pos+1);
    121                     helper.restoreEntity(stream);
    122                 } else {
    123                     if (!alreadyComplained) {
    124                         Log.w(TAG, "Couldn't find helper for: '" + rawKey + "'");
    125                         alreadyComplained = true;
    126                     }
    127                 }
    128             } else {
    129                 if (!alreadyComplained) {
    130                     Log.w(TAG, "Entity with no prefix: '" + rawKey + "'");
    131                     alreadyComplained = true;
    132                 }
    133             }
    134             input.skipEntityData(); // In case they didn't consume the data.
    135         }
    136 
    137         // Write out the state files -- mHelpers is a TreeMap, so the order is well defined.
    138         for (BackupHelper helper: mHelpers.values()) {
    139             helper.writeNewStateDescription(newState);
    140         }
    141     }
    142 
    143     private static native int readHeader_native(Header h, FileDescriptor fd);
    144     private static native int skipChunk_native(FileDescriptor fd, int bytesToSkip);
    145 
    146     private static native int allocateHeader_native(Header h, FileDescriptor fd);
    147     private static native int writeHeader_native(Header h, FileDescriptor fd, int pos);
    148 }
    149 
    150