1 /*
2 * Copyright (c) 1997, 2010, 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 * @(#)UUDecoderStream.java 1.8 02/07/08
28 */
29
30
31
32 package com.sun.xml.internal.messaging.saaj.packaging.mime.util;
33
34 import java.io.*;
35
36 /**
37 * This class implements a UUDecoder. 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 * @author Bill Shannon
44 */
45
46 public class UUDecoderStream extends FilterInputStream {
47 private String name;
48 private int mode;
49
50 private byte[] buffer; // cache of decoded bytes
51 private int bufsize = 0; // size of the cache
52 private int index = 0; // index into the cache
53 private boolean gotPrefix = false;
54 private boolean gotEnd = false;
55 private LineInputStream lin;
56
57 /**
58 * Create a UUdecoder that decodes the specified input stream
59 * @param in the input stream
60 */
61 public UUDecoderStream(InputStream in) {
62 super(in);
63 lin = new LineInputStream(in);
64 buffer = new byte[45]; // max decoded chars in a line = 45
65 }
66
67 /**
68 * Read the next decoded byte from this input stream. The byte
69 * is returned as an <code>int</code> in the range <code>0</code>
70 * to <code>255</code>. If no byte is available because the end of
71 * the stream has been reached, the value <code>-1</code> is returned.
72 * This method blocks until input data is available, the end of the
73 * stream is detected, or an exception is thrown.
74 *
75 * @return next byte of data, or <code>-1</code> if the end of
76 * stream is reached.
77 * @exception IOException if an I/O error occurs.
78 * @see java.io.FilterInputStream#in
79 */
80
81 public int read() throws IOException {
82 if (index >= bufsize) {
83 readPrefix();
84 if (!decode())
85 return -1;
86 index = 0; // reset index into buffer
87 }
88 return buffer[index++] & 0xff; // return lower byte
89 }
90
91 public int read(byte[] buf, int off, int len) throws IOException {
92 int i, c;
93 for (i = 0; i < len; i++) {
94 if ((c = read()) == -1) {
95 if (i == 0) // At end of stream, so we should
96 i = -1; // return -1, NOT 0.
97 break;
98 }
99 buf[off+i] = (byte)c;
100 }
101 return i;
102 }
103
104 public boolean markSupported() {
105 return false;
106 }
107
108 public int available() throws IOException {
109 // This is only an estimate, since in.available()
110 // might include CRLFs too ..
111 return ((in.available() * 3)/4 + (bufsize-index));
112 }
113
114 /**
115 * Get the "name" field from the prefix. This is meant to
116 * be the pathname of the decoded file
117 *
118 * @return name of decoded file
119 * @exception IOException if an I/O error occurs.
120 */
121 public String getName() throws IOException {
122 readPrefix();
123 return name;
124 }
125
126 /**
127 * Get the "mode" field from the prefix. This is the permission
128 * mode of the source file.
129 *
130 * @return permission mode of source file
131 * @exception IOException if an I/O error occurs.
132 */
133 public int getMode() throws IOException {
134 readPrefix();
135 return mode;
136 }
137
138 /**
139 * UUencoded streams start off with the line:
140 * "begin <mode> <filename>"
141 * Search for this prefix and gobble it up.
142 */
143 private void readPrefix() throws IOException {
144 if (gotPrefix) // got the prefix
145 return;
146
147 String s;
148 for (;;) {
149 // read till we get the prefix: "begin MODE FILENAME"
150 s = lin.readLine(); // NOTE: readLine consumes CRLF pairs too
151 if (s == null)
152 throw new IOException("UUDecoder error: No Begin");
153 if (s.regionMatches(true, 0, "begin", 0, 5)) {
154 try {
155 mode = Integer.parseInt(s.substring(6,9));
156 } catch (NumberFormatException ex) {
157 throw new IOException("UUDecoder error: " + ex.toString());
158 }
159 name = s.substring(10);
160 gotPrefix = true;
161 return;
162 }
163 }
164 }
165
166 private boolean decode() throws IOException {
167
168 if (gotEnd)
169 return false;
170 bufsize = 0;
171 String line;
172 do {
173 line = lin.readLine();
174
175 /*
176 * Improperly encoded data sometimes omits the zero length
177 * line that starts with a space character, we detect the
178 * following "end" line here.
179 */
180 if (line == null)
181 throw new IOException("Missing End");
182 if (line.regionMatches(true, 0, "end", 0, 3)) {
183 gotEnd = true;
184 return false;
185 }
186 } while (line.length() == 0);
187 int count = line.charAt(0);
188 if (count < ' ')
189 throw new IOException("Buffer format error");
190
191 /*
192 * The first character in a line is the number of original (not
193 * the encoded atoms) characters in the line. Note that all the
194 * code below has to handle the <SPACE> character that indicates
195 * end of encoded stream.
196 */
197 count = (count - ' ') & 0x3f;
198
199 if (count == 0) {
200 line = lin.readLine();
201 if (line == null || !line.regionMatches(true, 0, "end", 0, 3))
202 throw new IOException("Missing End");
203 gotEnd = true;
204 return false;
205 }
206
207 int need = ((count * 8)+5)/6;
208 //System.out.println("count " + count + ", need " + need + ", len " + line.length());
209 if (line.length() < need + 1)
210 throw new IOException("Short buffer error");
211
212 int i = 1;
213 byte a, b;
214 /*
215 * A correct uuencoder always encodes 3 characters at a time, even
216 * if there aren't 3 characters left. But since some people out
217 * there have broken uuencoders we handle the case where they
218 * don't include these "unnecessary" characters.
219 */
220 while (bufsize < count) {
221 // continue decoding until we get 'count' decoded chars
222 a = (byte)((line.charAt(i++) - ' ') & 0x3f);
223 b = (byte)((line.charAt(i++) - ' ') & 0x3f);
224 buffer[bufsize++] = (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3));
225
226 if (bufsize < count) {
227 a = b;
228 b = (byte)((line.charAt(i++) - ' ') & 0x3f);
229 buffer[bufsize++] =
230 (byte)(((a << 4) & 0xf0) | ((b >>> 2) & 0xf));
231 }
232
233 if (bufsize < count) {
234 a = b;
235 b = (byte)((line.charAt(i++) - ' ') & 0x3f);
236 buffer[bufsize++] = (byte)(((a << 6) & 0xc0) | (b & 0x3f));
237 }
238 }
239 return true;
240 }
241
242 /*** begin TEST program *****
243 public static void main(String argv[]) throws Exception {
244 FileInputStream infile = new FileInputStream(argv[0]);
245 UUDecoderStream decoder = new UUDecoderStream(infile);
246 int c;
247
248 try {
249 while ((c = decoder.read()) != -1)
250 System.out.write(c);
251 System.out.flush();
252 } catch (Exception e) {
253 e.printStackTrace();
254 }
255 }
256 **** end TEST program ****/
257 }