1/*
2 * Copyright (c) 1997, 2013, 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/* FROM mail.jar */
27package com.sun.xml.internal.org.jvnet.mimepull;
28
29import java.io.*;
30
31/**
32 * This class is to support reading CRLF terminated lines that
33 * contain only US-ASCII characters from an input stream. Provides
34 * functionality that is similar to the deprecated
35 * <code>DataInputStream.readLine()</code>. Expected use is to read
36 * lines as String objects from a RFC822 stream.
37 *
38 * It is implemented as a FilterInputStream, so one can just wrap
39 * this class around any input stream and read bytes from this filter.
40 *
41 * @author John Mani
42 */
43
44final class LineInputStream extends FilterInputStream {
45
46    private char[] lineBuffer = null; // reusable byte buffer
47    private static int MAX_INCR = 1024*1024;    // 1MB
48
49    public LineInputStream(InputStream in) {
50        super(in);
51    }
52
53    /**
54     * Read a line containing only ASCII characters from the input
55     * stream. A line is terminated by a CR or NL or CR-NL sequence.
56     * A common error is a CR-CR-NL sequence, which will also terminate
57     * a line.
58     * The line terminator is not returned as part of the returned
59     * String. Returns null if no data is available. <p>
60     *
61     * This class is similar to the deprecated
62     * <code>DataInputStream.readLine()</code>
63     */
64    public String readLine() throws IOException {
65        //InputStream in = this.in;
66        char[] buf = lineBuffer;
67
68        if (buf == null) {
69            buf = lineBuffer = new char[128];
70        }
71
72        int c1;
73        int room = buf.length;
74        int offset = 0;
75
76        while ((c1 = in.read()) != -1) {
77            if (c1 == '\n') {
78                break;
79            } else if (c1 == '\r') {
80                // Got CR, is the next char NL ?
81                boolean twoCRs = false;
82                if (in.markSupported()) {
83                    in.mark(2);
84                }
85                int c2 = in.read();
86                if (c2 == '\r') {               // discard extraneous CR
87                    twoCRs = true;
88                    c2 = in.read();
89                }
90                if (c2 != '\n') {
91                    /*
92                     * If the stream supports it (which we hope will always
93                     * be the case), reset to after the first CR.  Otherwise,
94                     * we wrap a PushbackInputStream around the stream so we
95                     * can unread the characters we don't need.  The only
96                     * problem with that is that the caller might stop
97                     * reading from this LineInputStream, throw it away,
98                     * and then start reading from the underlying stream.
99                     * If that happens, the pushed back characters will be
100                     * lost forever.
101                     */
102                    if (in.markSupported()) {
103                        in.reset();
104                    } else {
105                        if (!(in instanceof PushbackInputStream)) {
106                            in /*= this.in*/ = new PushbackInputStream(in, 2);
107                        }
108                        if (c2 != -1) {
109                            ((PushbackInputStream)in).unread(c2);
110                        }
111                        if (twoCRs) {
112                            ((PushbackInputStream)in).unread('\r');
113                        }
114                    }
115                }
116                break; // outa here.
117            }
118
119            // Not CR, NL or CR-NL ...
120            // .. Insert the byte into our byte buffer
121            if (--room < 0) { // No room, need to grow.
122                if (buf.length < MAX_INCR) {
123                    buf = new char[buf.length * 2];
124                } else {
125                    buf = new char[buf.length + MAX_INCR];
126                }
127                room = buf.length - offset - 1;
128                System.arraycopy(lineBuffer, 0, buf, 0, offset);
129                lineBuffer = buf;
130            }
131            buf[offset++] = (char)c1;
132        }
133
134        if ((c1 == -1) && (offset == 0)) {
135            return null;
136        }
137
138        return String.copyValueOf(buf, 0, offset);
139    }
140}
141