1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package org.apache.geronimo.javamail.util;
21
22 import java.io.IOException;
23 import java.io.Reader;
24
25 /**
26 * An implementation of an OutputStream that performs MIME linebreak
27 * canonicalization and "byte-stuff" so that data content does not get mistaken
28 * for a message data-end marker (CRLF.CRLF)l
29 *
30 * @version $Rev: 597135 $ $Date: 2007-11-21 11:26:57 -0500 (Wed, 21 Nov 2007) $
31 */
32 public class MIMEInputReader extends Reader {
33
34 // the wrappered output stream.
35 protected Reader source;
36
37 // a flag to indicate we've just processed a line break. This is used for
38 // byte stuffing purposes. This
39 // is initially true, because if the first character of the content is a
40 // period, we need to byte-stuff
41 // immediately.
42 protected boolean atLineBreak = true;
43 // we've hit the terminating marker on the data
44 protected boolean endOfData = false;
45
46
47 /**
48 * Create an input reader that reads from the source input reader
49 *
50 * @param out
51 * The wrapped Reader
52 */
53 public MIMEInputReader(Reader source) {
54 this.source = source;
55 }
56
57 /**
58 * Concrete implementation of the Reader read()
59 * abstract method. This appears to be the only
60 * abstract method, so all of the other reads must
61 * funnel through this method.
62 *
63 * @param buffer The buffer to fill.
64 * @param off The offset to start adding characters.
65 * @param len The number of requested characters.
66 *
67 * @return The actual count of characters read. Returns -1
68 * if we hit an EOF without reading any characters.
69 * @exception IOException
70 */
71 public int read(char buffer[], int off, int len) throws IOException {
72 // we've been asked for nothing, we'll return nothing.
73 if (len == 0) {
74 return 0;
75 }
76
77 // have we hit the end of data? Return a -1 indicator
78 if (endOfData) {
79 return -1;
80 }
81
82 // number of bytes read
83 int bytesRead = 0;
84
85 int lastRead;
86
87 while (bytesRead < len && (lastRead = source.read()) >= 0) {
88 // We are checking for the end of a multiline response
89 // the format is .CRLF
90
91 // we also have to check for byte-stuffing situation
92 // where we remove a leading period.
93 if (atLineBreak && lastRead == '.') {
94 // step to the next character
95 lastRead = source.read();
96 // we have ".CR"...this is our end of stream
97 // marker. Consume the LF from the reader and return
98 if (lastRead == '\r') {
99 source.read();
100 // no more reads from this point.
101 endOfData = true;
102 break;
103 }
104 // the next character SHOULD be a ".". We swallow the first
105 // dot and just write the next character to the buffer
106 atLineBreak = false;
107 }
108 else if (lastRead == '\n') {
109 // hit an end-of-line marker?
110 // remember we just had a line break
111 atLineBreak = true;
112 }
113 else
114 {
115 // something other than a line break character
116 atLineBreak = false;
117 }
118 // add the character to the buffer
119 buffer[off++] = (char)lastRead;
120 bytesRead++;
121 }
122
123 // we must have had an EOF condition of some sort
124 if (bytesRead == 0) {
125 return -1;
126 }
127 // return the actual length read in
128 return bytesRead;
129 }
130
131 /**
132 * Close the stream. This is a NOP for this stream.
133 *
134 * @exception IOException
135 */
136 public void close() throws IOException {
137 // does nothing
138 }
139 }
140