[Classpathx-javamail] gnu.mail.util.DotTerminatedInputStream.java

[Doug Porter]

/*
 * DotTerminatedInputStream.java
 * Copyright (C) 2003 Doug Porter
 * 
 * This file is part of GNU JavaMail, a library.
 * 
 * GNU JavaMail 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 of the License, or
 * (at your option) any later version.
 * 
 * GNU JavaMail 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 
 USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */

package gnu.mail.util;

import java.io.BufferedInputStream;
import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;

import javax.mail.Session;

/**
 * An input stream that returns end of stream on the sequence "CRLF .
 CRLF".
 * <p>
 * If you want to read until a line with a single dot, wrap your stream
 in 
 * this class before passing it to LineInputStream.
 * <p>
 * This implementation is dependent on methods ultimately calling read() 
 * for input.
 * <p>
 * @author Doug Porter
 */
public class DotTerminatedInputStream
extends ReadFilterInputStream
{
    static final int MarkReadLimit = 5;
    static final int EOS = -1;
    
    private boolean isEOS = false;
    
    /**
    * Constructor.
    * @param in the inner input stream
    */
    public DotTerminatedInputStream (InputStream in) {
        // we need mark/reset
        super (in.markSupported () ? in : new BufferedInputStream (in));
    }
    
    /**
     * Returns the number of bytes available.
     * <p>
     * If a dot line has been seen, returns zero.
     * @return the number of bytes available
     */
    public int available ()
    throws IOException
    {
        int n;
        if (isEOS) {
            n = 0;
        }
        else {
            n = super.available ();
        }
        
        return n;
    }
    
    /**
     * Returns the next byte from this stream.
     * <p>
     * If a dot line has been seen, returns -1.
     * @return The next byte from this stream, or -1 on dot line or end
     of stream
     */
    public int read ()
    throws IOException
    {
        final int CR = 13;
        final int LF = 10;
        final int DOT = '.';
        
        int b;
        
        if (isEOS) {
            
            b = EOS;
            
        }
        else {
            
            b = super.read ();
            mark (MarkReadLimit); 
            if (b == CR &&
                super.read () == LF &&
                super.read () == DOT &&
                super.read () == CR &&
                super.read () == LF) {
                    
                isEOS = true;
                
            }
            
            else {
                // our streams often have stripped CRs (CRLFInputStream)
                
                reset ();
                mark (MarkReadLimit);
                
                if (b == LF &&
                    super.read () == DOT &&
                    super.read () == LF) {

                    isEOS = true;
                    
                }
            }
            
            if (isEOS) {
                    
                // end of stream
                b = EOS;
                
            }
            
            else {
                
                reset ();
                
            }
        }
        
        return b;
    }
}

-- 
  Doug Porter
  address@hidden

-- 
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