content: /*
   * Copyright (c) 1995, 2006, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package java.io;
  
  import java.io.*;
  
  /**
   * A piped output stream can be connected to a piped input stream
   * to create a communications pipe. The piped output stream is the
   * sending end of the pipe. Typically, data is written to a
   * <code>PipedOutputStream</code> object by one thread and data is
   * read from the connected <code>PipedInputStream</code> by some
   * other thread. Attempting to use both objects from a single thread
   * is not recommended as it may deadlock the thread.
   * The pipe is said to be <a name=BROKEN> <i>broken</i> </a> if a
   * thread that was reading data bytes from the connected piped input
   * stream is no longer alive.
   *
   * @author  James Gosling
   * @see     PipedInputStream
   * @since   JDK1.0
   */
  public
  class PipedOutputStream extends OutputStream {
  
          /* REMIND: identification of the read and write sides needs to be
             more sophisticated.  Either using thread groups (but what about
             pipes within a thread?) or using finalization (but it may be a
             long time until the next GC). */
      private PipedInputStream sink;
  
      /**
       * Creates a piped output stream connected to the specified piped
       * input stream. Data bytes written to this stream will then be
       * available as input from <code>snk</code>.
       *
       * @param      snk   The piped input stream to connect to.
       * @exception  IOException  if an I/O error occurs.
       */
      public PipedOutputStream(PipedInputStream snk)  throws IOException {
          connect(snk);
      }
  
      /**
       * Creates a piped output stream that is not yet connected to a
       * piped input stream. It must be connected to a piped input stream,
       * either by the receiver or the sender, before being used.
       *
       * @see     PipedInputStream#connect(PipedOutputStream)
       * @see     PipedOutputStream#connect(PipedInputStream)
       */
      public PipedOutputStream() {
      }
  
      /**
       * Connects this piped output stream to a receiver. If this object
       * is already connected to some other piped input stream, an
       * <code>IOException</code> is thrown.
       * <p>
       * If <code>snk</code> is an unconnected piped input stream and
       * <code>src</code> is an unconnected piped output stream, they may
       * be connected by either the call:
       * <blockquote><pre>
       * src.connect(snk)</pre></blockquote>
       * or the call:
       * <blockquote><pre>
       * snk.connect(src)</pre></blockquote>
       * The two calls have the same effect.
       *
       * @param      snk   the piped input stream to connect to.
       * @exception  IOException  if an I/O error occurs.
       */
      public synchronized void connect(PipedInputStream snk) throws IOException {
          if (snk == null) {
              throw new NullPointerException();
          } else if (sink != null || snk.connected) {
              throw new IOException("Already connected");
          }
          sink = snk;
          snk.in = -1;
          snk.out = 0;
          snk.connected = true;
      }
  
      /**
       * Writes the specified <code>byte</code> to the piped output stream.
       * <p>
       * Implements the <code>write</code> method of <code>OutputStream</code>.
       *
       * @param      b   the <code>byte</code> to be written.
       * @exception IOException if the pipe is <a href=#BROKEN> broken</a>,
       *          {@link #connect(PipedInputStream) unconnected},
       *          closed, or if an I/O error occurs.
       */
      public void write(int b)  throws IOException {
          if (sink == null) {
              throw new IOException("Pipe not connected");
          }
          sink.receive(b);
      }
  
      /**
       * Writes <code>len</code> bytes from the specified byte array
       * starting at offset <code>off</code> to this piped output stream.
       * This method blocks until all the bytes are written to the output
       * stream.
       *
       * @param      b     the data.
       * @param      off   the start offset in the data.
       * @param      len   the number of bytes to write.
       * @exception IOException if the pipe is <a href=#BROKEN> broken</a>,
       *          {@link #connect(PipedInputStream) unconnected},
       *          closed, or if an I/O error occurs.
       */
      public void write(byte b[], int off, int len) throws IOException {
          if (sink == null) {
              throw new IOException("Pipe not connected");
          } else if (b == null) {
              throw new NullPointerException();
          } else if ((off < 0) || (off > b.length) || (len < 0) ||
                     ((off + len) > b.length) || ((off + len) < 0)) {
              throw new IndexOutOfBoundsException();
          } else if (len == 0) {
              return;
          }
          sink.receive(b, off, len);
      }
  
      /**
       * Flushes this output stream and forces any buffered output bytes
       * to be written out.
       * This will notify any readers that bytes are waiting in the pipe.
       *
       * @exception IOException if an I/O error occurs.
       */
      public synchronized void flush() throws IOException {
          if (sink != null) {
              synchronized (sink) {
                  sink.notifyAll();
              }
          }
      }
  
      /**
       * Closes this piped output stream and releases any system resources
       * associated with this stream. This stream may no longer be used for
       * writing bytes.
       *
       * @exception  IOException  if an I/O error occurs.
       */
      public void close()  throws IOException {
          if (sink != null) {
              sink.receivedLast();
          }
      }
  }
  