aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: /* FROM mail.jar */
aoqi@0: package com.sun.xml.internal.org.jvnet.mimepull;
aoqi@0: 
aoqi@0: import java.io.*;
aoqi@0: 
aoqi@0: /**
aoqi@0:  * This class implements a QP Decoder. It is implemented as
aoqi@0:  * a FilterInputStream, so one can just wrap this class around
aoqi@0:  * any input stream and read bytes from this filter. The decoding
aoqi@0:  * is done as the bytes are read out.
aoqi@0:  *
aoqi@0:  * @author John Mani
aoqi@0:  */
aoqi@0: 
aoqi@0: final class QPDecoderStream extends FilterInputStream {
aoqi@0:     private byte[] ba = new byte[2];
aoqi@0:     private int spaces = 0;
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Create a Quoted Printable decoder that decodes the specified
aoqi@0:      * input stream.
aoqi@0:      * @param in        the input stream
aoqi@0:      */
aoqi@0:     public QPDecoderStream(InputStream in) {
aoqi@0:         super(new PushbackInputStream(in, 2)); // pushback of size=2
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Read the next decoded byte from this input stream. The byte
aoqi@0:      * is returned as an <code>int</code> in the range <code>0</code>
aoqi@0:      * to <code>255</code>. If no byte is available because the end of
aoqi@0:      * the stream has been reached, the value <code>-1</code> is returned.
aoqi@0:      * This method blocks until input data is available, the end of the
aoqi@0:      * stream is detected, or an exception is thrown.
aoqi@0:      *
aoqi@0:      * @return     the next byte of data, or <code>-1</code> if the end of the
aoqi@0:      *             stream is reached.
aoqi@0:      * @exception  IOException  if an I/O error occurs.
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public int read() throws IOException {
aoqi@0:         if (spaces > 0) {
aoqi@0:             // We have cached space characters, return one
aoqi@0:             spaces--;
aoqi@0:             return ' ';
aoqi@0:         }
aoqi@0: 
aoqi@0:         int c = in.read();
aoqi@0: 
aoqi@0:         if (c == ' ') {
aoqi@0:             // Got space, keep reading till we get a non-space char
aoqi@0:             while ((c = in.read()) == ' ') {
aoqi@0:                 spaces++;
aoqi@0:             }
aoqi@0: 
aoqi@0:             if (c == '\r' || c == '\n' || c == -1) {
aoqi@0:                 spaces = 0;
aoqi@0:             } else {
aoqi@0:                 // The non-space char is NOT CR/LF, the spaces are valid.
aoqi@0:                 ((PushbackInputStream)in).unread(c);
aoqi@0:                 c = ' ';
aoqi@0:             }
aoqi@0:             return c; // return either <SPACE> or <CR/LF>
aoqi@0:         }
aoqi@0:         else if (c == '=') {
aoqi@0:             // QP Encoded atom. Decode the next two bytes
aoqi@0:             int a = in.read();
aoqi@0: 
aoqi@0:             if (a == '\n') {
aoqi@0:                 /* Hmm ... not really confirming QP encoding, but lets
aoqi@0:                  * allow this as a LF terminated encoded line .. and
aoqi@0:                  * consider this a soft linebreak and recurse to fetch
aoqi@0:                  * the next char.
aoqi@0:                  */
aoqi@0:                 return read();
aoqi@0:             } else if (a == '\r') {
aoqi@0:                 // Expecting LF. This forms a soft linebreak to be ignored.
aoqi@0:                 int b = in.read();
aoqi@0:                 if (b != '\n') {
aoqi@0:                     ((PushbackInputStream)in).unread(b);
aoqi@0:                 }
aoqi@0:                 return read();
aoqi@0:             } else if (a == -1) {
aoqi@0:                 // Not valid QP encoding, but we be nice and tolerant here !
aoqi@0:                 return -1;
aoqi@0:             } else {
aoqi@0:                 ba[0] = (byte)a;
aoqi@0:                 ba[1] = (byte)in.read();
aoqi@0:                 try {
aoqi@0:                     return ASCIIUtility.parseInt(ba, 0, 2, 16);
aoqi@0:                 } catch (NumberFormatException nex) {
aoqi@0:                     /*
aoqi@0:                     System.err.println(
aoqi@0:                         "Illegal characters in QP encoded stream: " +
aoqi@0:                         ASCIIUtility.toString(ba, 0, 2)
aoqi@0:                     );
aoqi@0:                     */
aoqi@0: 
aoqi@0:                     ((PushbackInputStream)in).unread(ba);
aoqi@0:                     return c;
aoqi@0:                 }
aoqi@0:             }
aoqi@0:         }
aoqi@0:         return c;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Reads up to <code>len</code> decoded bytes of data from this input stream
aoqi@0:      * into an array of bytes. This method blocks until some input is
aoqi@0:      * available.
aoqi@0:      * <p>
aoqi@0:      *
aoqi@0:      * @param      buf   the buffer into which the data is read.
aoqi@0:      * @param      off   the start offset of the data.
aoqi@0:      * @param      len   the maximum number of bytes read.
aoqi@0:      * @return     the total number of bytes read into the buffer, or
aoqi@0:      *             <code>-1</code> if there is no more data because the end of
aoqi@0:      *             the stream has been reached.
aoqi@0:      * @exception  IOException  if an I/O error occurs.
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public int read(byte[] buf, int off, int len) throws IOException {
aoqi@0:         int i, c;
aoqi@0:         for (i = 0; i < len; i++) {
aoqi@0:             if ((c = read()) == -1) {
aoqi@0:                 if (i == 0) {
aoqi@0:                     i = -1; // return -1 , NOT 0.
aoqi@0:                 }
aoqi@0:                 break;
aoqi@0:             }
aoqi@0:             buf[off+i] = (byte)c;
aoqi@0:         }
aoqi@0:         return i;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Skips over and discards n bytes of data from this stream.
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public long skip(long n) throws IOException {
aoqi@0:         long skipped = 0;
aoqi@0:         while (n-- > 0 && read() >= 0) {
aoqi@0:             skipped++;
aoqi@0:         }
aoqi@0:         return skipped;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Tests if this input stream supports marks. Currently this class
aoqi@0:      * does not support marks
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public boolean markSupported() {
aoqi@0:         return false;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**
aoqi@0:      * Returns the number of bytes that can be read from this input
aoqi@0:      * stream without blocking. The QP algorithm does not permit
aoqi@0:      * a priori knowledge of the number of bytes after decoding, so
aoqi@0:      * this method just invokes the <code>available</code> method
aoqi@0:      * of the original input stream.
aoqi@0:      */
aoqi@0:     @Override
aoqi@0:     public int available() throws IOException {
aoqi@0:         // This is bogus ! We don't really know how much
aoqi@0:         // bytes are available *after* decoding
aoqi@0:         return in.available();
aoqi@0:     }
aoqi@0: 
aoqi@0:     /**** begin TEST program
aoqi@0:     public static void main(String argv[]) throws Exception {
aoqi@0:         FileInputStream infile = new FileInputStream(argv[0]);
aoqi@0:         QPDecoderStream decoder = new QPDecoderStream(infile);
aoqi@0:         int c;
aoqi@0: 
aoqi@0:         while ((c = decoder.read()) != -1)
aoqi@0:             System.out.print((char)c);
aoqi@0:         System.out.println();
aoqi@0:     }
aoqi@0:     *** end TEST program ****/
aoqi@0: }