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/*
* Copyright (C) 2009 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 android.backup;
import android.content.Context;
import android.os.ParcelFileDescriptor;
import android.util.Log;
import java.io.File;
import java.io.FileDescriptor;
/** @hide */
public class FileBackupHelper {
private static final String TAG = "FileBackupHelper";
Context mContext;
String mKeyPrefix;
public FileBackupHelper(Context context) {
mContext = context;
}
public FileBackupHelper(Context context, String keyPrefix) {
mContext = context;
mKeyPrefix = keyPrefix;
}
/**
* Based on oldState, determine which of the files from the application's data directory
* need to be backed up, write them to the data stream, and fill in newState with the
* state as it exists now.
*/
public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
ParcelFileDescriptor newState, String[] files) {
// file names
File base = mContext.getFilesDir();
final int N = files.length;
String[] fullPaths = new String[N];
for (int i=0; i<N; i++) {
fullPaths[i] = (new File(base, files[i])).getAbsolutePath();
}
// keys
String[] keys = makeKeys(mKeyPrefix, files);
// go
performBackup_checked(oldState, data, newState, fullPaths, keys);
}
/**
* If keyPrefix is not null, prepend it to each of the strings in <code>original</code>;
* otherwise, return original.
*/
static String[] makeKeys(String keyPrefix, String[] original) {
if (keyPrefix != null) {
String[] keys;
final int N = original.length;
keys = new String[N];
for (int i=0; i<N; i++) {
keys[i] = keyPrefix + ':' + original[i];
}
return keys;
} else {
return original;
}
}
/**
* Check the parameters so the native code doens't have to throw all the exceptions
* since it's easier to do that from java.
*/
static void performBackup_checked(ParcelFileDescriptor oldState, BackupDataOutput data,
ParcelFileDescriptor newState, String[] files, String[] keys) {
if (files.length == 0) {
return;
}
// files must be all absolute paths
for (String f: files) {
if (f.charAt(0) != '/') {
throw new RuntimeException("files must have all absolute paths: " + f);
}
}
// the length of files and keys must be the same
if (files.length != keys.length) {
throw new RuntimeException("files.length=" + files.length
+ " keys.length=" + keys.length);
}
// oldStateFd can be null
FileDescriptor oldStateFd = oldState != null ? oldState.getFileDescriptor() : null;
FileDescriptor newStateFd = newState.getFileDescriptor();
if (newStateFd == null) {
throw new NullPointerException();
}
int err = performBackup_native(oldStateFd, data.mBackupWriter, newStateFd, files, keys);
if (err != 0) {
// TODO: more here
throw new RuntimeException("Backup failed 0x" + Integer.toHexString(err));
}
}
native private static int performBackup_native(FileDescriptor oldState,
int data, FileDescriptor newState, String[] files, String[] keys);
}
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