content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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
   *
   *   https://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 org.apache.avro.util;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.Buffer;
  import java.nio.ByteBuffer;
  
  public class ReusableByteBufferInputStream extends InputStream {
  
    private static final ByteBuffer EMPTY_BUFFER = ByteBuffer.allocate(0);
  
    // work around issues compiling with Java11 but running with 8
    // due to ByteBuffer overriding several methods
    private ByteBuffer byteBuffer = EMPTY_BUFFER;
    private Buffer buffer = byteBuffer;
    private int mark = 0;
  
    public void setByteBuffer(ByteBuffer buf) {
      // do not modify the buffer that is passed in
      this.byteBuffer = buf.duplicate();
      this.buffer = byteBuffer;
      this.mark = buf.position();
    }
  
    @Override
    public int read() throws IOException {
      if (buffer.hasRemaining()) {
        return byteBuffer.get() & 0xff;
      } else {
        return -1;
      }
    }
  
    @Override
    public int read(byte[] b, int off, int len) throws IOException {
      if (buffer.remaining() <= 0) {
        return -1;
      }
      // allow IndexOutOfBoundsException to be thrown by ByteBuffer#get
      int bytesToRead = Math.min(len, buffer.remaining());
      byteBuffer.get(b, off, bytesToRead);
      return bytesToRead;
    }
  
    @Override
    public long skip(long n) throws IOException {
      if (n <= 0) {
        // n may be negative and results in skipping 0 bytes, according to javadoc
        return 0;
      }
  
      // this catches n > Integer.MAX_VALUE
      int bytesToSkip = n > buffer.remaining() ? buffer.remaining() : (int) n;
      buffer.position(buffer.position() + bytesToSkip);
      return bytesToSkip;
    }
  
    @Override
    public synchronized void mark(int readLimit) {
      // readLimit is ignored. there is no requirement to implement readLimit, it
      // is a way for implementations to avoid buffering too much. since all data
      // for this stream is held in memory, this has no need for such a limit.
      this.mark = buffer.position();
    }
  
    @Override
    public synchronized void reset() throws IOException {
      buffer.position(mark);
    }
  
    @Override
    public boolean markSupported() {
      return true;
    }
  }
  