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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   * @(#)LineInputStream.java   1.7 03/01/07
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 is to support reading CRLF terminated lines that
38   * contain only US-ASCII characters from an input stream. Provides
39   * functionality that is similar to the deprecated
40   * <code>DataInputStream.readLine()</code>. Expected use is to read
41   * lines as String objects from a RFC822 stream.
42   *
43   * It is implemented as a FilterInputStream, so one can just wrap
44   * this class around any input stream and read bytes from this filter.
45   *
46   * @author John Mani
47   */
48  
49  public final class LineInputStream extends FilterInputStream {
50  
51      private char[] lineBuffer = null; // reusable byte buffer
52  
53      public LineInputStream(InputStream in) {
54          super(in);
55      }
56  
57      /**
58       * Read a line containing only ASCII characters from the input
59       * stream. A line is terminated by a CR or NL or CR-NL sequence.
60       * A common error is a CR-CR-NL sequence, which will also terminate
61       * a line.
62       * The line terminator is not returned as part of the returned
63       * String. Returns null if no data is available. <p>
64       *
65       * This class is similar to the deprecated
66       * <code>DataInputStream.readLine()</code>
67       */
68      public String readLine() throws IOException {
69          InputStream in = this.in;
70          char[] buf = lineBuffer;
71  
72          if (buf == null)
73              buf = lineBuffer = new char[128];
74  
75          int c1;
76          int room = buf.length;
77          int offset = 0;
78  
79          while ((c1 = in.read()) != -1) {
80              if (c1 == '\n') // Got NL, outa here.
81                  break;
82              else if (c1 == '\r') {
83                  // Got CR, is the next char NL ?
84                  int c2 = in.read();
85                  if (c2 == '\r')         // discard extraneous CR
86                      c2 = in.read();
87                  if (c2 != '\n') {
88                      // If not NL, push it back
89                      if (!(in instanceof PushbackInputStream))
90                          in = this.in = new PushbackInputStream(in);
91                      ((PushbackInputStream)in).unread(c2);
92                  }
93                  break; // outa here.
94              }
95  
96              // Not CR, NL or CR-NL ...
97              // .. Insert the byte into our byte buffer
98              if (--room < 0) { // No room, need to grow.
99                  buf = new char[offset + 128];
100                 room = buf.length - offset - 1;
101                 System.arraycopy(lineBuffer, 0, buf, 0, offset);
102                 lineBuffer = buf;
103             }
104             buf[offset++] = (char)c1;
105         }
106 
107         if ((c1 == -1) && (offset == 0))
108             return null;
109 
110         return String.copyValueOf(buf, 0, offset);
111     }
112 }