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/* CRLFInputStream.java --

   Copyright (C) 2002, 2003, 2004, 2006  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;

import java.io.BufferedInputStream;

import java.io.IOException;

import java.io.InputStream;

/**

 * An input stream that filters out CR/LF pairs into LFs.

 *

 * @author Chris Burdess (dog@gnu.org)

 */

public class CRLFInputStream

  extends InputStream

{

  /**

   * The CR octet.

   */

  public static final int CR = 13;

  /**

   * The LF octet.

   */

  public static final int LF = 10;

  /**

   * The underlying input stream.

   */

  protected InputStream in;

  private boolean doReset;

  /**

   * Constructs a CR/LF input stream connected to the specified input

   * stream.

   */

  public CRLFInputStream(InputStream in)

  {

    this.in = in.markSupported() ? in : new BufferedInputStream(in);

  }

  /**

   * Reads the next byte of data from this input stream.

   * Returns -1 if the end of the stream has been reached.

   * @exception IOException if an I/O error occurs

   */

  public int read()

    throws IOException

  {

    int c = in.read();

    if (c == CR)

      {

        in.mark(1);

        int d = in.read();

        if (d == LF)

          {

            c = d;

          }

        else

          {

            in.reset();

          }

      }

    return c;

  }

  /**

   * Reads up to b.length bytes of data from this input stream into

   * an array of bytes.

   * Returns -1 if the end of the stream has been reached.

   * @exception IOException if an I/O error occurs

   */

  public int read(byte[] b)

    throws IOException

  {

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

  }

  /**

   * Reads up to len bytes of data from this input stream into an

   * array of bytes, starting at the specified offset.

   * Returns -1 if the end of the stream has been reached.

   * @exception IOException if an I/O error occurs

   */

  public int read(byte[] b, int off, int len)

    throws IOException

  {

    in.mark(len + 1);

    int l = in.read(b, off, len);

    if (l > 0)

      {

        int i = indexOfCRLF(b, off, l);

        if (doReset)

          {

            in.reset();

            if (i != -1)

              {

                l = in.read(b, off, (i + 1) - off); // read to CR

                in.read(); // skip LF

                b[i] = LF; // fix CR as LF

              }

            else

              {

                l = in.read(b, off, len); // CR(s) but no LF

              }

          }

      }

    return l;

  }

  private int indexOfCRLF(byte[] b, int off, int len)

    throws IOException

  {

    doReset = false;

    int end = off + len;

    int em1 = end - 1;

    for (int i = off; i < end; i++)

      {

        if (b[i] == CR)

          {

            int d;

            if (i == em1)

              {

                d = in.read();

                doReset = true;

              }

            else

              {

                d = b[i + 1];

              }

            if (d == LF)

              {

                doReset = true;

                return i;

              }

          }

      }

    return -1;

  }

}