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1   /*
2    * Copyright (c) 1997, 2012, 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 }