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/* LimitedLengthInputStream.java --

   Copyright (C) 2005, 2008 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.net.protocol.http;

import java.io.IOException;

import java.io.InputStream;

/**

 * InputStream that limits the total number of bytes that can be read

 * from an underlying stream.  In addition to limiting the number of

 * bytes read, close() is not propagated to the underlying stream.

 *

 * @author David Daney (ddaney@avtrex.com)

 */

class LimitedLengthInputStream

  extends InputStream

{

  private long remainingLen;

  private boolean restrictLen;

  private HTTPConnection connection;

  private boolean eof;

  private InputStream in;

  private boolean doClose;

  private void handleClose()

    throws IOException

  {

    eof = true;

    if (doClose)

      in.close();

    else

      connection.release();

    in = null;

    connection = null;

  }

  /**

   * Constructor.

   *

   * @param in the underlying stream

   *

   * @param maxLen the maximum number of bytes to read

   *

   * @param restrictLen if true the number of bytes that can be read

   * from this stream will be limited to maxLen, otherwise the number

   * of bytes is not restricted.

   *

   * @param con the HTTPConnection associated with this stream

   *

   * @param doClose if true con will be closed when finished reading,

   * else it will be placed back in the connection pool.

   *

   */

  LimitedLengthInputStream(InputStream in,

                           long maxLen,

                           boolean restrictLen,

                           HTTPConnection con,

                           boolean doClose)

    throws IOException

  {

    this.in = in;

    this.remainingLen = maxLen;

    this.restrictLen = restrictLen;

    this.connection = con;

    this.doClose = doClose;

    if (restrictLen)

      {

        if (maxLen < 0)

          throw new IllegalArgumentException();

        else if (maxLen == 0)

          handleClose(); // Nothing to do, release the connection.

      }

  }

  public synchronized int read()

    throws IOException

  {

    if (eof)

      return -1; // EOF

    int r;

    if (restrictLen)

      {

        r = in.read();

        if (-1 != r)

          remainingLen--;

        if (0 == remainingLen)

          handleClose();

      }

    else

      {

        r = in.read();

        if (r == -1)

          handleClose();

      }

    return r;

  }

  public int read(byte[] buffer)

    throws IOException

  {

    return read(buffer, 0, buffer.length);

  }

  public synchronized int read(byte[] buffer, int offset, int length)

    throws IOException

  {

    if (eof)

      return -1; // EOF

    if (restrictLen && length > remainingLen)

      length = (int) remainingLen;

    int r = in.read(buffer, offset, length);

    if (-1 == r)

      handleClose();

    if (restrictLen && r > 0)

      {

        remainingLen -= r;

        if (0 == remainingLen)

          handleClose();

      }

    return r;

  }

  public synchronized long skip(long n)

    throws IOException

  {

    if (eof)

      return 0;

    if (restrictLen && n > remainingLen)

      n = remainingLen;

    long r = in.skip(n);

    if (restrictLen)

      {

        remainingLen -= r;

        if (0 == remainingLen)

          handleClose();

      }

    return r;

  }

  public synchronized int available()

    throws IOException

  {

    if (eof)

      return 0;

    int a = in.available();

    if (restrictLen && a > remainingLen)

      a = (int)remainingLen;

    return a;

  }

  public synchronized void close()

    throws IOException

  {

    if (eof)

      return;

    // If we get to here, the stream was not fully read.  Just throw

    // it away.

    doClose = true;

    handleClose();

  }

}