1/*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26/*
27 * @(#)QPDecoderStream.java   1.9 02/04/02
28 */
29
30
31
32package com.sun.xml.internal.messaging.saaj.packaging.mime.util;
33
34import java.io.*;
35
36/**
37 * This class implements a QP Decoder. It is implemented as
38 * a FilterInputStream, so one can just wrap this class around
39 * any input stream and read bytes from this filter. The decoding
40 * is done as the bytes are read out.
41 *
42 * @author John Mani
43 */
44
45public class QPDecoderStream extends FilterInputStream {
46    protected byte[] ba = new byte[2];
47    protected int spaces = 0;
48
49    /**
50     * Create a Quoted Printable decoder that decodes the specified
51     * input stream.
52     * @param in        the input stream
53     */
54    public QPDecoderStream(InputStream in) {
55        super(new PushbackInputStream(in, 2)); // pushback of size=2
56    }
57
58    /**
59     * Read the next decoded byte from this input stream. The byte
60     * is returned as an <code>int</code> in the range <code>0</code>
61     * to <code>255</code>. If no byte is available because the end of
62     * the stream has been reached, the value <code>-1</code> is returned.
63     * This method blocks until input data is available, the end of the
64     * stream is detected, or an exception is thrown.
65     *
66     * @return     the next byte of data, or <code>-1</code> if the end of the
67     *             stream is reached.
68     * @exception  IOException  if an I/O error occurs.
69     */
70    @Override
71    public int read() throws IOException {
72        if (spaces > 0) {
73            // We have cached space characters, return one
74            spaces--;
75            return ' ';
76        }
77
78        int c = in.read();
79
80        if (c == ' ') {
81            // Got space, keep reading till we get a non-space char
82            while ((c = in.read()) == ' ')
83                spaces++;
84
85            if (c == '\r' || c == '\n' || c == -1)
86                // If the non-space char is CR/LF/EOF, the spaces we got
87                // so far is junk introduced during transport. Junk 'em.
88                spaces = 0;
89            else {
90                // The non-space char is NOT CR/LF, the spaces are valid.
91                ((PushbackInputStream)in).unread(c);
92                c = ' ';
93            }
94            return c; // return either <SPACE> or <CR/LF>
95        }
96        else if (c == '=') {
97            // QP Encoded atom. Decode the next two bytes
98            int a = in.read();
99
100            if (a == '\n') {
101                /* Hmm ... not really confirming QP encoding, but lets
102                 * allow this as a LF terminated encoded line .. and
103                 * consider this a soft linebreak and recurse to fetch
104                 * the next char.
105                 */
106                return read();
107            } else if (a == '\r') {
108                // Expecting LF. This forms a soft linebreak to be ignored.
109                int b = in.read();
110                if (b != '\n')
111                    /* Not really confirming QP encoding, but
112                     * lets allow this as well.
113                     */
114                    ((PushbackInputStream)in).unread(b);
115                return read();
116            } else if (a == -1) {
117                // Not valid QP encoding, but we be nice and tolerant here !
118                return -1;
119            } else {
120                ba[0] = (byte)a;
121                ba[1] = (byte)in.read();
122                try {
123                    return ASCIIUtility.parseInt(ba, 0, 2, 16);
124                } catch (NumberFormatException nex) {
125                    /*
126                    System.err.println(
127                        "Illegal characters in QP encoded stream: " +
128                        ASCIIUtility.toString(ba, 0, 2)
129                    );
130                    */
131
132                    ((PushbackInputStream)in).unread(ba);
133                    return c;
134                }
135            }
136        }
137        return c;
138    }
139
140    /**
141     * Reads up to <code>len</code> decoded bytes of data from this input stream
142     * into an array of bytes. This method blocks until some input is
143     * available.
144     * <p>
145     *
146     * @param      buf   the buffer into which the data is read.
147     * @param      off   the start offset of the data.
148     * @param      len   the maximum number of bytes read.
149     * @return     the total number of bytes read into the buffer, or
150     *             <code>-1</code> if there is no more data because the end of
151     *             the stream has been reached.
152     * @exception  IOException  if an I/O error occurs.
153     */
154    @Override
155    public int read(byte[] buf, int off, int len) throws IOException {
156        int i, c;
157        for (i = 0; i < len; i++) {
158            if ((c = read()) == -1) {
159                if (i == 0) // At end of stream, so we should
160                    i = -1; // return -1 , NOT 0.
161                break;
162            }
163            buf[off+i] = (byte)c;
164        }
165        return i;
166    }
167
168    /**
169     * Tests if this input stream supports marks. Currently this class
170     * does not support marks
171     */
172    @Override
173    public boolean markSupported() {
174        return false;
175    }
176
177    /**
178     * Returns the number of bytes that can be read from this input
179     * stream without blocking. The QP algorithm does not permit
180     * a priori knowledge of the number of bytes after decoding, so
181     * this method just invokes the <code>available</code> method
182     * of the original input stream.
183     */
184    @Override
185    public int available() throws IOException {
186        // This is bogus ! We don't really know how much
187        // bytes are available *after* decoding
188        return in.available();
189    }
190
191    /**** begin TEST program
192    public static void main(String argv[]) throws Exception {
193        FileInputStream infile = new FileInputStream(argv[0]);
194        QPDecoderStream decoder = new QPDecoderStream(infile);
195        int c;
196
197        while ((c = decoder.read()) != -1)
198            System.out.print((char)c);
199        System.out.println();
200    }
201    *** end TEST program ****/
202}
203