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    public class QuotedPrintableDecoderStream extends FilterInputStream {
036        // our decoder for processing the data
037        protected QuotedPrintableEncoder decoder;
038    
039    
040        /**
041         * Stream constructor.
042         *
043         * @param in     The InputStream this stream is filtering.
044         */
045        public QuotedPrintableDecoderStream(InputStream in) {
046            super(in);
047            decoder = new QuotedPrintableEncoder();
048        }
049    
050        // in order to function as a filter, these streams need to override the different
051        // read() signatures.
052    
053    
054        /**
055         * Read a single byte from the stream.
056         *
057         * @return The next byte of the stream.  Returns -1 for an EOF condition.
058         * @exception IOException
059         */
060        public int read() throws IOException
061        {
062            // just get a single byte from the decoder
063            return decoder.decode(in);
064        }
065    
066    
067        /**
068         * Read a buffer of data from the input stream.
069         *
070         * @param buffer The target byte array the data is placed into.
071         * @param offset The starting offset for the read data.
072         * @param length How much data is requested.
073         *
074         * @return The number of bytes of data read.
075         * @exception IOException
076         */
077        public int read(byte [] buffer, int offset, int length) throws IOException {
078    
079            for (int i = 0; i < length; i++) {
080                int ch = decoder.decode(in);
081                if (ch == -1) {
082                    return i == 0 ? -1 : i;
083                }
084                buffer[offset + i] = (byte)ch;
085            }
086    
087            return length;
088        }
089    
090    
091        /**
092         * Indicate whether this stream supports the mark() operation.
093         *
094         * @return Always returns false.
095         */
096        public boolean markSupported() {
097            return false;
098        }
099    
100    
101        /**
102         * Give an estimate of how much additional data is available
103         * from this stream.
104         *
105         * @return Always returns -1.
106         * @exception IOException
107         */
108        public int available() throws IOException {
109            // this is almost impossible to determine at this point
110            return -1;
111        }
112    }
113    
114