content: /*
   * 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();
      }
  }
  