content: /*
   * Copyright (C) 2014 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.internal.util;
  
  import libcore.io.Streams;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * Reads exact number of bytes from wrapped stream, returning EOF once those
   * bytes have been read.
   */
  public class SizedInputStream extends InputStream {
      private final InputStream mWrapped;
      private long mLength;
  
      public SizedInputStream(InputStream wrapped, long length) {
          mWrapped = wrapped;
          mLength = length;
      }
  
      @Override
      public void close() throws IOException {
          super.close();
          mWrapped.close();
      }
  
      @Override
      public int read() throws IOException {
          return Streams.readSingleByte(this);
      }
  
      @Override
      public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException {
          if (mLength <= 0) {
              return -1;
          } else if (byteCount > mLength) {
              byteCount = (int) mLength;
          }
  
          final int n = mWrapped.read(buffer, byteOffset, byteCount);
          if (n == -1) {
              if (mLength > 0) {
                  throw new IOException("Unexpected EOF; expected " + mLength + " more bytes");
              }
          } else {
              mLength -= n;
          }
          return n;
      }
  }
  