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/*
* Copyright (C) 2018 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 com.android.server.backup.encryption.chunking;
import com.android.internal.annotations.VisibleForTesting;
import java.io.IOException;
import java.io.OutputStream;
/** Writes backup data to a diff script, using a {@link SingleStreamDiffScriptWriter}. */
public class DiffScriptBackupWriter implements BackupWriter {
/**
* The maximum size of a chunk in the diff script. The diff script writer {@code mWriter} will
* buffer this many bytes in memory.
*/
private static final int ENCRYPTION_DIFF_SCRIPT_MAX_CHUNK_SIZE_BYTES = 1024 * 1024;
private final SingleStreamDiffScriptWriter mWriter;
private long mBytesWritten;
/**
* Constructs a new writer which writes the diff script to the given output stream, using the
* maximum new chunk size {@code ENCRYPTION_DIFF_SCRIPT_MAX_CHUNK_SIZE_BYTES}.
*/
public static DiffScriptBackupWriter newInstance(OutputStream outputStream) {
SingleStreamDiffScriptWriter writer =
new SingleStreamDiffScriptWriter(
outputStream, ENCRYPTION_DIFF_SCRIPT_MAX_CHUNK_SIZE_BYTES);
return new DiffScriptBackupWriter(writer);
}
@VisibleForTesting
DiffScriptBackupWriter(SingleStreamDiffScriptWriter writer) {
mWriter = writer;
}
@Override
public void writeBytes(byte[] bytes) throws IOException {
for (byte b : bytes) {
mWriter.writeByte(b);
}
mBytesWritten += bytes.length;
}
@Override
public void writeChunk(long start, int length) throws IOException {
mWriter.writeChunk(start, length);
mBytesWritten += length;
}
@Override
public long getBytesWritten() {
return mBytesWritten;
}
@Override
public void flush() throws IOException {
mWriter.flush();
}
}
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