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.InputStream;
59 import java.io.PushbackInputStream;
60
61 /****
62 * This class wraps an input stream, replacing all occurrences
63 * of <CR><LF> (carriage return followed by a linefeed),
64 * which is the NETASCII standard for representing a newline, with the
65 * local line separator representation. You would use this class to
66 * implement ASCII file transfers requiring conversion from NETASCII.
67 * <p>
68 * <p>
69 * @author Daniel F. Savarese
70 ***/
71
72 public final class FromNetASCIIInputStream extends PushbackInputStream
73 {
74 static final boolean _noConversionRequired;
75 static final String _lineSeparator;
76 static final byte[] _lineSeparatorBytes;
77
78 static {
79 _lineSeparator = System.getProperty("line.separator");
80 _noConversionRequired = _lineSeparator.equals("\r\n");
81 _lineSeparatorBytes = _lineSeparator.getBytes();
82 }
83
84 private int __length = 0;
85
86 /****
87 * Returns true if the NetASCII line separator differs from the system
88 * line separator, false if they are the same. This method is useful
89 * to determine whether or not you need to instantiate a
90 * FromNetASCIIInputStream object.
91 * <p>
92 * @return True if the NETASCII line separator differs from the local
93 * system line separator, false if they are the same.
94 ***/
95 public static final boolean isConversionRequired()
96 {
97 return !_noConversionRequired;
98 }
99
100 /****
101 * Creates a FromNetASCIIInputStream instance that wraps an existing
102 * InputStream.
103 ***/
104 public FromNetASCIIInputStream(InputStream input)
105 {
106 super(input, _lineSeparatorBytes.length + 1);
107 }
108
109
110 private int __read() throws IOException
111 {
112 int ch;
113
114 ch = super.read();
115
116 if (ch == '\r')
117 {
118 ch = super.read();
119 if (ch == '\n')
120 {
121 unread(_lineSeparatorBytes);
122 ch = super.read();
123 // This is a kluge for read(byte[], ...) to read the right amount
124 --__length;
125 }
126 else
127 {
128 if (ch != -1)
129 unread(ch);
130 return '\r';
131 }
132 }
133
134 return ch;
135 }
136
137
138 /****
139 * Reads and returns the next byte in the stream. If the end of the
140 * message has been reached, returns -1. Note that a call to this method
141 * may result in multiple reads from the underlying input stream in order
142 * to convert NETASCII line separators to the local line separator format.
143 * This is transparent to the programmer and is only mentioned for
144 * completeness.
145 * <p>
146 * @return The next character in the stream. Returns -1 if the end of the
147 * stream has been reached.
148 * @exception IOException If an error occurs while reading the underlying
149 * stream.
150 ***/
151 public int read() throws IOException
152 {
153 if (_noConversionRequired)
154 return super.read();
155
156 return __read();
157 }
158
159
160 /****
161 * Reads the next number of bytes from the stream into an array and
162 * returns the number of bytes read. Returns -1 if the end of the
163 * stream has been reached.
164 * <p>
165 * @param buffer The byte array in which to store the data.
166 * @return The number of bytes read. Returns -1 if the
167 * end of the message has been reached.
168 * @exception IOException If an error occurs in reading the underlying
169 * stream.
170 ***/
171 public int read(byte buffer[]) throws IOException
172 {
173 return read(buffer, 0, buffer.length);
174 }
175
176
177 /****
178 * Reads the next number of bytes from the stream into an array and returns
179 * the number of bytes read. Returns -1 if the end of the
180 * message has been reached. The characters are stored in the array
181 * starting from the given offset and up to the length specified.
182 * <p>
183 * @param buffer The byte array in which to store the data.
184 * @param offset The offset into the array at which to start storing data.
185 * @param length The number of bytes to read.
186 * @return The number of bytes read. Returns -1 if the
187 * end of the stream has been reached.
188 * @exception IOException If an error occurs while reading the underlying
189 * stream.
190 ***/
191 public int read(byte buffer[], int offset, int length) throws IOException
192 {
193 int ch, off;
194
195 if (length < 1)
196 return 0;
197
198 ch = available();
199
200 __length = (length > ch ? ch : length);
201
202 // If nothing is available, block to read only one character
203 if (__length < 1)
204 __length = 1;
205
206 if (_noConversionRequired)
207 return super.read(buffer, offset, __length);
208
209 if ((ch = __read()) == -1)
210 return -1;
211
212 off = offset;
213
214 do
215 {
216 buffer[offset++] = (byte)ch;
217 }
218 while (--__length > 0 && (ch = __read()) != -1);
219
220
221 return (offset - off);
222 }
223
224
225 // PushbackInputStream in JDK 1.1.3 returns the wrong thing
226 /****
227 * Returns the number of bytes that can be read without blocking EXCEPT
228 * when newline conversions have to be made somewhere within the
229 * available block of bytes. In other words, you really should not
230 * rely on the value returned by this method if you are trying to avoid
231 * blocking.
232 ***/
233 public int available() throws IOException
234 {
235 return (buf.length - pos) + in.available();
236 }
237
238 }
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