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 /*

    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 }