Package java.net

Source Code of java.net.SocketInputStream

/*
* @(#)SocketInputStream.java  1.35 05/11/17
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/

package java.net;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;

import sun.net.ConnectionResetException;

/**
* This stream extends FileInputStream to implement a
* SocketInputStream. Note that this class should <b>NOT</b> be
* public.
*
* @version     1.35, 11/17/05
* @author  Jonathan Payne
* @author  Arthur van Hoff
*/
class SocketInputStream extends FileInputStream
{
    static {
        init();
    }
   
    private boolean eof;
    private PlainSocketImpl impl = null;
    private byte temp[];
    private Socket socket = null;

    /**
     * Creates a new SocketInputStream. Can only be called
     * by a Socket. This method needs to hang on to the owner Socket so
     * that the fd will not be closed.
     * @param impl the implemented socket input stream
     */
    SocketInputStream(PlainSocketImpl impl) throws IOException {
  super(impl.getFileDescriptor());
  this.impl = impl;
  socket = impl.getSocket();
    }

    /**
     * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
     * object associated with this file input stream.</p>
     *
     * The <code>getChannel</code> method of <code>SocketInputStream</code>
     * returns <code>null</code> since it is a socket based stream.</p>
     *
     * @return  the file channel associated with this file input stream
     *
     * @since 1.4
     * @spec JSR-51
     */
    public final FileChannel getChannel() {
  return null;
    }

    /**
     * Reads into an array of bytes at the specified offset using
     * the received socket primitive.
     * @param fd the FileDescriptor
     * @param b the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @param timeout the read timeout in ms
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    private native int socketRead0(FileDescriptor fd,
                 byte b[], int off, int len,
           int timeout)
  throws IOException;

    /**
     * Reads into a byte array data from the socket.
     * @param b the buffer into which the data is read
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    public int read(byte b[]) throws IOException {
  return read(b, 0, b.length);
    }

    /**
     * Reads into a byte array <i>b</i> at offset <i>off</i>,
     * <i>length</i> bytes of data.
     * @param b the buffer into which the data is read
     * @param off the start offset of the data
     * @param len the maximum number of bytes read
     * @return the actual number of bytes read, -1 is
     *          returned when the end of the stream is reached.
     * @exception IOException If an I/O error has occurred.
     */
    public int read(byte b[], int off, int length) throws IOException {
  int n;

  // EOF already encountered
  if (eof) {
      return -1;
  }

  // connection reset
  if (impl.isConnectionReset()) {
      throw new SocketException("Connection reset");
  }

  // bounds check
  if (length <= 0 || off < 0 || off + length > b.length) {
      if (length == 0) {
    return 0;
      }
      throw new ArrayIndexOutOfBoundsException();
  }

  boolean gotReset = false;

  // acquire file descriptor and do the read
  FileDescriptor fd = impl.acquireFD();
   try
      n = socketRead0(fd, b, off, length, impl.getTimeout());
      if (n > 0) {
    return n;
      }
  } catch (ConnectionResetException rstExc) {
      gotReset = true;
  } finally {
      impl.releaseFD();
  }

  /*
   * We receive a "connection reset" but there may be bytes still
   * buffered on the socket
   */
  if (gotReset) {
      impl.setConnectionResetPending();
      impl.acquireFD();
      try {
          n = socketRead0(fd, b, off, length, impl.getTimeout());
    if (n > 0) {
        return n;
    }
      } catch (ConnectionResetException rstExc) {
      } finally {
    impl.releaseFD();
      }
  }

  /*
   * If we get here we are at EOF, the socket has been closed,
   * or the connection has been reset.
   */
        if (impl.isClosedOrPending()) {
            throw new SocketException("Socket closed");
        }
  if (impl.isConnectionResetPending()) {
      impl.setConnectionReset();
  }
  if (impl.isConnectionReset()) {
      throw new SocketException("Connection reset");
  }
  eof = true;
  return -1;
    }

    /**
     * Reads a single byte from the socket.
     */
    public int read() throws IOException {
  if (eof) {
      return -1;
  }
  temp = new byte[1];
   int n = read(temp, 0, 1);
  if (n <= 0) {
      return -1;
  }
  return temp[0] & 0xff;
    }

    /**
     * Skips n bytes of input.
     * @param n the number of bytes to skip
     * @return  the actual number of bytes skipped.
     * @exception IOException If an I/O error has occurred.
     */
    public long skip(long numbytes) throws IOException {
  if (numbytes <= 0) {
      return 0;
  }
  long n = numbytes;
  int buflen = (int) Math.min(1024, n);
  byte data[] = new byte[buflen];
  while (n > 0) {
      int r = read(data, 0, (int) Math.min((long) buflen, n));
      if (r < 0) {
    break;
      }
      n -= r;
  }
  return numbytes - n;
    }

    /**
     * Returns the number of bytes that can be read without blocking.
     * @return the number of immediately available bytes
     */
    public int available() throws IOException {
  return impl.available();
    }

    /**
     * Closes the stream.
     */
    private boolean closing = false;
    public void close() throws IOException {
  // Prevent recursion. See BugId 4484411
  if (closing)
      return;
  closing = true;
  if (socket != null) {
      if (!socket.isClosed())
    socket.close();
  } else
      impl.close();
  closing = false;
    }

    void setEOF(boolean eof) {
  this.eof = eof;
    }

    /**
     * Overrides finalize, the fd is closed by the Socket.
     */
    protected void finalize() {}

    /**
     * Perform class load-time initializations.
     */
    private native static void init();
}
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