content: /*
   * Copyright (C) 2014 The Android Open Source Project
   * Copyright (c) 1995, 2013, 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 libcore.io.IoUtils;
  
  /**
   * A piped input stream should be connected
   * to a piped output stream; the piped  input
   * stream then provides whatever data bytes
   * are written to the piped output  stream.
   * Typically, data is read from a <code>PipedInputStream</code>
   * object by one thread  and data is written
   * to the corresponding <code>PipedOutputStream</code>
   * by some  other thread. Attempting to use
   * both objects from a single thread is not
   * recommended, as it may deadlock the thread.
   * The piped input stream contains a buffer,
   * decoupling read operations from write operations,
   * within limits.
   * A pipe is said to be <a name="BROKEN"> <i>broken</i> </a> if a
   * thread that was providing data bytes to the connected
   * piped output stream is no longer alive.
   *
   * @author  James Gosling
   * @see     PipedOutputStream
   * @since   JDK1.0
   */
  public class PipedInputStream extends InputStream {
      boolean closedByWriter = false;
      volatile boolean closedByReader = false;
      boolean connected = false;
  
          /* 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). */
      Thread readSide;
      Thread writeSide;
  
      private static final int DEFAULT_PIPE_SIZE = 1024;
  
      /**
       * The default size of the pipe's circular input buffer.
       * @since   JDK1.1
       */
      // This used to be a constant before the pipe size was allowed
      // to change. This field will continue to be maintained
      // for backward compatibility.
      protected static final int PIPE_SIZE = DEFAULT_PIPE_SIZE;
  
      /**
       * The circular buffer into which incoming data is placed.
       * @since   JDK1.1
       */
      protected byte buffer[];
  
      /**
       * The index of the position in the circular buffer at which the
       * next byte of data will be stored when received from the connected
       * piped output stream. <code>in&lt;0</code> implies the buffer is empty,
       * <code>in==out</code> implies the buffer is full
       * @since   JDK1.1
       */
      protected int in = -1;
  
      /**
       * The index of the position in the circular buffer at which the next
       * byte of data will be read by this piped input stream.
       * @since   JDK1.1
       */
      protected int out = 0;
  
      /**
       * Creates a <code>PipedInputStream</code> so
       * that it is connected to the piped output
       * stream <code>src</code>. Data bytes written
       * to <code>src</code> will then be  available
       * as input from this stream.
       *
       * @param      src   the stream to connect to.
       * @exception  IOException  if an I/O error occurs.
       */
      public PipedInputStream(PipedOutputStream src) throws IOException {
          this(src, DEFAULT_PIPE_SIZE);
      }
  
      /**
       * Creates a <code>PipedInputStream</code> so that it is
       * connected to the piped output stream
       * <code>src</code> and uses the specified pipe size for
       * the pipe's buffer.
       * Data bytes written to <code>src</code> will then
       * be available as input from this stream.
       *
       * @param      src   the stream to connect to.
       * @param      pipeSize the size of the pipe's buffer.
       * @exception  IOException  if an I/O error occurs.
       * @exception  IllegalArgumentException if {@code pipeSize <= 0}.
       * @since      1.6
       */
      public PipedInputStream(PipedOutputStream src, int pipeSize)
              throws IOException {
           initPipe(pipeSize);
           connect(src);
      }
  
      /**
       * Creates a <code>PipedInputStream</code> so
       * that it is not yet {@linkplain #connect(PipedOutputStream)
       * connected}.
       * It must be {@linkplain PipedOutputStream#connect(
       * PipedInputStream) connected} to a
       * <code>PipedOutputStream</code> before being used.
       */
      public PipedInputStream() {
          initPipe(DEFAULT_PIPE_SIZE);
      }
  
      /**
       * Creates a <code>PipedInputStream</code> so that it is not yet
       * {@linkplain #connect(PipedOutputStream) connected} and
       * uses the specified pipe size for the pipe's buffer.
       * It must be {@linkplain PipedOutputStream#connect(
       * PipedInputStream)
       * connected} to a <code>PipedOutputStream</code> before being used.
       *
       * @param      pipeSize the size of the pipe's buffer.
       * @exception  IllegalArgumentException if {@code pipeSize <= 0}.
       * @since      1.6
       */
      public PipedInputStream(int pipeSize) {
          initPipe(pipeSize);
      }
  
      private void initPipe(int pipeSize) {
           if (pipeSize <= 0) {
              throw new IllegalArgumentException("Pipe Size <= 0");
           }
           buffer = new byte[pipeSize];
      }
  
      /**
       * Causes this piped input stream to be connected
       * to the piped  output stream <code>src</code>.
       * If this object is already connected to some
       * other piped output  stream, an <code>IOException</code>
       * is thrown.
       * <p>
       * If <code>src</code> is an
       * unconnected piped output stream and <code>snk</code>
       * is an unconnected piped input stream, they
       * may be connected by either the call:
       *
       * <pre><code>snk.connect(src)</code> </pre>
       * <p>
       * or the call:
       *
       * <pre><code>src.connect(snk)</code> </pre>
       * <p>
       * The two calls have the same effect.
       *
       * @param      src   The piped output stream to connect to.
       * @exception  IOException  if an I/O error occurs.
       */
      public void connect(PipedOutputStream src) throws IOException {
          src.connect(this);
      }
  
      /**
       * Receives a byte of data.  This method will block if no input is
       * available.
       * @param b the byte being received
       * @exception IOException If the pipe is <a href="#BROKEN"> <code>broken</code></a>,
       *          {@link #connect(PipedOutputStream) unconnected},
       *          closed, or if an I/O error occurs.
       * @since     JDK1.1
       */
      protected synchronized void receive(int b) throws IOException {
          checkStateForReceive();
          writeSide = Thread.currentThread();
          if (in == out)
              awaitSpace();
          if (in < 0) {
              in = 0;
              out = 0;
          }
          buffer[in++] = (byte)(b & 0xFF);
          if (in >= buffer.length) {
              in = 0;
          }
      }
  
      /**
       * Receives data into an array of bytes.  This method will
       * block until some input is available.
       * @param b the buffer into which the data is received
       * @param off the start offset of the data
       * @param len the maximum number of bytes received
       * @exception IOException If the pipe is <a href="#BROKEN"> broken</a>,
       *           {@link #connect(PipedOutputStream) unconnected},
       *           closed,or if an I/O error occurs.
       */
      synchronized void receive(byte b[], int off, int len)  throws IOException {
          checkStateForReceive();
          writeSide = Thread.currentThread();
          int bytesToTransfer = len;
          while (bytesToTransfer > 0) {
              if (in == out)
                  awaitSpace();
              int nextTransferAmount = 0;
              if (out < in) {
                  nextTransferAmount = buffer.length - in;
              } else if (in < out) {
                  if (in == -1) {
                      in = out = 0;
                      nextTransferAmount = buffer.length - in;
                  } else {
                      nextTransferAmount = out - in;
                  }
              }
              if (nextTransferAmount > bytesToTransfer)
                  nextTransferAmount = bytesToTransfer;
              assert(nextTransferAmount > 0);
              System.arraycopy(b, off, buffer, in, nextTransferAmount);
              bytesToTransfer -= nextTransferAmount;
              off += nextTransferAmount;
              in += nextTransferAmount;
              if (in >= buffer.length) {
                  in = 0;
              }
          }
      }
  
      private void checkStateForReceive() throws IOException {
          if (!connected) {
              throw new IOException("Pipe not connected");
          } else if (closedByWriter || closedByReader) {
              throw new IOException("Pipe closed");
          } else if (readSide != null && !readSide.isAlive()) {
              throw new IOException("Read end dead");
          }
      }
  
      private void awaitSpace() throws IOException {
          while (in == out) {
              checkStateForReceive();
  
              /* full: kick any waiting readers */
              notifyAll();
              try {
                  wait(1000);
              } catch (InterruptedException ex) {
                  // Android-changed: re-set the thread's interrupt status
                  // throw new java.io.InterruptedIOException();
                  IoUtils.throwInterruptedIoException();
              }
          }
      }
  
      /**
       * Notifies all waiting threads that the last byte of data has been
       * received.
       */
      synchronized void receivedLast() {
          closedByWriter = true;
          notifyAll();
      }
  
      /**
       * Reads the next byte of data from this piped input stream. The
       * value byte is returned as an <code>int</code> in the range
       * <code>0</code> to <code>255</code>.
       * This method blocks until input data is available, the end of the
       * stream is detected, or an exception is thrown.
       *
       * @return     the next byte of data, or <code>-1</code> if the end of the
       *             stream is reached.
       * @exception  IOException  if the pipe is
       *           {@link #connect(PipedOutputStream) unconnected},
       *           <a href="#BROKEN"> <code>broken</code></a>, closed,
       *           or if an I/O error occurs.
       */
      public synchronized int read()  throws IOException {
          if (!connected) {
              throw new IOException("Pipe not connected");
          } else if (closedByReader) {
              throw new IOException("Pipe closed");
          } else if (writeSide != null && !writeSide.isAlive()
                     && !closedByWriter && (in < 0)) {
              throw new IOException("Write end dead");
          }
  
          readSide = Thread.currentThread();
          int trials = 2;
          while (in < 0) {
              if (closedByWriter) {
                  /* closed by writer, return EOF */
                  return -1;
              }
              if ((writeSide != null) && (!writeSide.isAlive()) && (--trials < 0)) {
                  throw new IOException("Pipe broken");
              }
              /* might be a writer waiting */
              notifyAll();
              try {
                  wait(1000);
              } catch (InterruptedException ex) {
                  // Android-changed: re-set the thread's interrupt status
                  // throw new java.io.InterruptedIOException();
                  IoUtils.throwInterruptedIoException();
              }
          }
          int ret = buffer[out++] & 0xFF;
          if (out >= buffer.length) {
              out = 0;
          }
          if (in == out) {
              /* now empty */
              in = -1;
          }
  
          return ret;
      }
  
      /**
       * Reads up to <code>len</code> bytes of data from this piped input
       * stream into an array of bytes. Less than <code>len</code> bytes
       * will be read if the end of the data stream is reached or if
       * <code>len</code> exceeds the pipe's buffer size.
       * If <code>len </code> is zero, then no bytes are read and 0 is returned;
       * otherwise, the method blocks until at least 1 byte of input is
       * available, end of the stream has been detected, or an exception is
       * thrown.
       *
       * @param      b     the buffer into which the data is read.
       * @param      off   the start offset in the destination array <code>b</code>
       * @param      len   the maximum number of bytes read.
       * @return     the total number of bytes read into the buffer, or
       *             <code>-1</code> if there is no more data because the end of
       *             the stream has been reached.
       * @exception  NullPointerException If <code>b</code> is <code>null</code>.
       * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
       * <code>len</code> is negative, or <code>len</code> is greater than
       * <code>b.length - off</code>
       * @exception  IOException if the pipe is <a href="#BROKEN"> <code>broken</code></a>,
       *           {@link #connect(PipedOutputStream) unconnected},
       *           closed, or if an I/O error occurs.
       */
      public synchronized int read(byte b[], int off, int len)  throws IOException {
          if (b == null) {
              throw new NullPointerException();
          } else if (off < 0 || len < 0 || len > b.length - off) {
              throw new IndexOutOfBoundsException();
          } else if (len == 0) {
              return 0;
          }
  
          /* possibly wait on the first character */
          int c = read();
          if (c < 0) {
              return -1;
          }
          b[off] = (byte) c;
          int rlen = 1;
          while ((in >= 0) && (len > 1)) {
  
              int available;
  
              if (in > out) {
                  available = Math.min((buffer.length - out), (in - out));
              } else {
                  available = buffer.length - out;
              }
  
              // A byte is read beforehand outside the loop
              if (available > (len - 1)) {
                  available = len - 1;
              }
              System.arraycopy(buffer, out, b, off + rlen, available);
              out += available;
              rlen += available;
              len -= available;
  
              if (out >= buffer.length) {
                  out = 0;
              }
              if (in == out) {
                  /* now empty */
                  in = -1;
              }
          }
          return rlen;
      }
  
      /**
       * Returns the number of bytes that can be read from this input
       * stream without blocking.
       *
       * @return the number of bytes that can be read from this input stream
       *         without blocking, or {@code 0} if this input stream has been
       *         closed by invoking its {@link #close()} method, or if the pipe
       *         is {@link #connect(PipedOutputStream) unconnected}, or
       *          <a href="#BROKEN"> <code>broken</code></a>.
       *
       * @exception  IOException  if an I/O error occurs.
       * @since   JDK1.0.2
       */
      public synchronized int available() throws IOException {
          if(in < 0)
              return 0;
          else if(in == out)
              return buffer.length;
          else if (in > out)
              return in - out;
          else
              return in + buffer.length - out;
      }
  
      /**
       * Closes this piped input stream and releases any system resources
       * associated with the stream.
       *
       * @exception  IOException  if an I/O error occurs.
       */
      public void close()  throws IOException {
          closedByReader = true;
          synchronized (this) {
              in = -1;
          }
      }
  }
  