001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *  http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing,
013     * software distributed under the License is distributed on an
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     * KIND, either express or implied.  See the License for the
016     * specific language governing permissions and limitations
017     * under the License.
018     */
019    
020    package org.apache.geronimo.mail.util;
021    
022    import java.io.ByteArrayOutputStream;
023    import java.io.FilterInputStream;
024    import java.io.IOException;
025    import java.io.InputStream;
026    import java.io.UnsupportedEncodingException;
027    
028    /**
029     * An implementation of a FilterOutputStream that decodes the
030     * stream data in Q-P encoding format.  This version does the
031     * decoding "on the fly" rather than decoding a single block of
032     * data.  Since this version is intended for use by the MimeUtilty class,
033     * it also handles line breaks in the encoded data.
034     *
035     * @version $Rev: 467553 $ $Date: 2006-10-25 06:01:51 +0200 (Mi, 25. Okt 2006) $
036     */
037    public class QuotedPrintableDecoderStream extends FilterInputStream {
038        // our decoder for processing the data
039        protected QuotedPrintableEncoder decoder;
040    
041    
042        /**
043         * Stream constructor.
044         *
045         * @param in     The InputStream this stream is filtering.
046         */
047        public QuotedPrintableDecoderStream(InputStream in) {
048            super(in);
049            decoder = new QuotedPrintableEncoder();
050        }
051    
052        // in order to function as a filter, these streams need to override the different
053        // read() signatures.
054    
055    
056        /**
057         * Read a single byte from the stream.
058         *
059         * @return The next byte of the stream.  Returns -1 for an EOF condition.
060         * @exception IOException
061         */
062        public int read() throws IOException
063        {
064            // just get a single byte from the decoder
065            return decoder.decode(in);
066        }
067    
068    
069        /**
070         * Read a buffer of data from the input stream.
071         *
072         * @param buffer The target byte array the data is placed into.
073         * @param offset The starting offset for the read data.
074         * @param length How much data is requested.
075         *
076         * @return The number of bytes of data read.
077         * @exception IOException
078         */
079        public int read(byte [] buffer, int offset, int length) throws IOException {
080    
081            for (int i = 0; i < length; i++) {
082                int ch = decoder.decode(in);
083                if (ch == -1) {
084                    return i;
085                }
086                buffer[offset + i] = (byte)ch;
087            }
088    
089            return length;
090        }
091    
092    
093        /**
094         * Indicate whether this stream supports the mark() operation.
095         *
096         * @return Always returns false.
097         */
098        public boolean markSupported() {
099            return false;
100        }
101    
102    
103        /**
104         * Give an estimate of how much additional data is available
105         * from this stream.
106         *
107         * @return Always returns -1.
108         * @exception IOException
109         */
110        public int available() throws IOException {
111            // this is almost impossible to determine at this point
112            return -1;
113        }
114    }
115    
116