1 package org.apache.commons.net.io;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache Commons" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import java.io.IOException;
58 import java.io.PushbackReader;
59 import java.io.Reader;
60
61 /***
62 * DotTerminatedMessageReader is a class used to read messages from a
63 * server that are terminated by a single dot followed by a
64 * <CR><LF>
65 * sequence and with double dots appearing at the begining of lines which
66 * do not signal end of message yet start with a dot. Various Internet
67 * protocols such as NNTP and POP3 produce messages of this type.
68 * <p>
69 * This class handles stripping of the duplicate period at the beginning
70 * of lines starting with a period, converts NETASCII newlines to the
71 * local line separator format, truncates the end of message indicator,
72 * and ensures you cannot read past the end of the message.
73 * @author <a href="mailto:savarese@apache.org">Daniel F. Savarese</a>
74 * @version $Id: DotTerminatedMessageReader.java,v 1.6 2003/01/26 04:33:32 brekke Exp $
75 */
76 public final class DotTerminatedMessageReader extends Reader
77 {
78 private static final String LS;
79 private static final char[] LS_CHARS;
80
81 static
82 {
83 LS = System.getProperty("line.separator");
84 LS_CHARS = LS.toCharArray();
85 }
86
87 private boolean atBeginning;
88 private boolean eof;
89 private int pos;
90 private char[] internalBuffer;
91 private PushbackReader internalReader;
92
93 /***
94 * Creates a DotTerminatedMessageReader that wraps an existing Reader
95 * input source.
96 * @param reader The Reader input source containing the message.
97 */
98 public DotTerminatedMessageReader(Reader reader)
99 {
100 super(reader);
101 internalBuffer = new char[LS_CHARS.length + 3];
102 pos = internalBuffer.length;
103 // Assumes input is at start of message
104 atBeginning = true;
105 eof = false;
106 internalReader = new PushbackReader(reader);
107 }
108
109 /***
110 * Reads and returns the next character in the message. If the end of the
111 * message has been reached, returns -1. Note that a call to this method
112 * may result in multiple reads from the underlying input stream to decode
113 * the message properly (removing doubled dots and so on). All of
114 * this is transparent to the programmer and is only mentioned for
115 * completeness.
116 * @return The next character in the message. Returns -1 if the end of the
117 * message has been reached.
118 * @exception IOException If an error occurs while reading the underlying
119 * stream.
120 */
121 public int read() throws IOException
122 {
123 int ch;
124
125 synchronized (lock)
126 {
127 if (pos < internalBuffer.length)
128 {
129 return internalBuffer[pos++];
130 }
131
132 if (eof)
133 {
134 return -1;
135 }
136
137 if ((ch = internalReader.read()) == -1)
138 {
139 eof = true;
140 return -1;
141 }
142
143 if (atBeginning)
144 {
145 atBeginning = false;
146 if (ch == '.')
147 {
148 ch = internalReader.read();
149
150 if (ch != '.')
151 {
152 // read newline
153 eof = true;
154 internalReader.read();
155 return -1;
156 }
157 else
158 {
159 return '.';
160 }
161 }
162 }
163
164 if (ch == '\r')
165 {
166 ch = internalReader.read();
167
168 if (ch == '\n')
169 {
170 ch = internalReader.read();
171
172 if (ch == '.')
173 {
174 ch = internalReader.read();
175
176 if (ch != '.')
177 {
178 // read newline and indicate end of file
179 internalReader.read();
180 eof = true;
181 }
182 else
183 {
184 internalBuffer[--pos] = (char) ch;
185 }
186 }
187 else
188 {
189 internalReader.unread(ch);
190 }
191
192 pos -= LS_CHARS.length;
193 System.arraycopy(LS_CHARS, 0, internalBuffer, pos,
194 LS_CHARS.length);
195 ch = internalBuffer[pos++];
196 }
197 else
198 {
199 internalBuffer[--pos] = (char) ch;
200 return '\r';
201 }
202 }
203
204 return ch;
205 }
206 }
207
208 /***
209 * Reads the next characters from the message into an array and
210 * returns the number of characters read. Returns -1 if the end of the
211 * message has been reached.
212 * @param buffer The character array in which to store the characters.
213 * @return The number of characters read. Returns -1 if the
214 * end of the message has been reached.
215 * @exception IOException If an error occurs in reading the underlying
216 * stream.
217 */
218 public int read(char[] buffer) throws IOException
219 {
220 return read(buffer, 0, buffer.length);
221 }
222
223 /***
224 * Reads the next characters from the message into an array and
225 * returns the number of characters read. Returns -1 if the end of the
226 * message has been reached. The characters are stored in the array
227 * starting from the given offset and up to the length specified.
228 * @param buffer The character array in which to store the characters.
229 * @param offset The offset into the array at which to start storing
230 * characters.
231 * @param length The number of characters to read.
232 * @return The number of characters read. Returns -1 if the
233 * end of the message has been reached.
234 * @exception IOException If an error occurs in reading the underlying
235 * stream.
236 */
237 public int read(char[] buffer, int offset, int length) throws IOException
238 {
239 int ch, off;
240 synchronized (lock)
241 {
242 if (length < 1)
243 {
244 return 0;
245 }
246 if ((ch = read()) == -1)
247 {
248 return -1;
249 }
250 off = offset;
251
252 do
253 {
254 buffer[offset++] = (char) ch;
255 }
256 while (--length > 0 && (ch = read()) != -1);
257
258 return (offset - off);
259 }
260 }
261
262 /***
263 * Determines if the message is ready to be read.
264 * @return True if the message is ready to be read, false if not.
265 * @exception IOException If an error occurs while checking the underlying
266 * stream.
267 */
268 public boolean ready() throws IOException
269 {
270 synchronized (lock)
271 {
272 return (pos < internalBuffer.length || internalReader.ready());
273 }
274 }
275
276 /***
277 * Closes the message for reading. This doesn't actually close the
278 * underlying stream. The underlying stream may still be used for
279 * communicating with the server and therefore is not closed.
280 * <p>
281 * If the end of the message has not yet been reached, this method
282 * will read the remainder of the message until it reaches the end,
283 * so that the underlying stream may continue to be used properly
284 * for communicating with the server. If you do not fully read
285 * a message, you MUST close it, otherwise your program will likely
286 * hang or behave improperly.
287 * @exception IOException If an error occurs while reading the
288 * underlying stream.
289 */
290 public void close() throws IOException
291 {
292 synchronized (lock)
293 {
294 if (internalReader == null)
295 {
296 return;
297 }
298
299 if (!eof)
300 {
301 while (read() != -1)
302 {
303 ;
304 }
305 }
306 eof = true;
307 atBeginning = false;
308 pos = internalBuffer.length;
309 internalReader = null;
310 }
311 }
312 }
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