content: /*
   * Copyright (C) 2016 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.google.android.exoplayer2.upstream;
  
  import com.google.android.exoplayer2.C;
  import java.io.IOException;
  
  /** Reads bytes from a data stream. */
  public interface DataReader {
    /**
     * Reads up to {@code length} bytes of data from the input.
     *
     * <p>If {@code readLength} is zero then 0 is returned. Otherwise, if no data is available because
     * the end of the opened range has been reached, then {@link C#RESULT_END_OF_INPUT} is returned.
     * Otherwise, the call will block until at least one byte of data has been read and the number of
     * bytes read is returned.
     *
     * @param buffer A target array into which data should be written.
     * @param offset The offset into the target array at which to write.
     * @param length The maximum number of bytes to read from the input.
     * @return The number of bytes read, or {@link C#RESULT_END_OF_INPUT} if the input has ended. This
     *     may be less than {@code length} because the end of the input (or available data) was
     *     reached, the method was interrupted, or the operation was aborted early for another reason.
     * @throws IOException If an error occurs reading from the input.
     */
    int read(byte[] buffer, int offset, int length) throws IOException;
  }
  