libjava/gnu/java/net/CRLFInputStream.java

   1 /* CRLFInputStream.java --
   2    Copyright (C) 2002, 2003, 2004  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package gnu.java.net;
  40
  41 import java.io.FilterInputStream;
  42 import java.io.InputStream;
  43 import java.io.IOException;
  44
  45 /**
  46  * An input stream that filters out CR/LF pairs into LFs.
  47  *
  48  * @author Chris Burdess (dog@gnu.org)
  49  */
  50 public class CRLFInputStream
  51   extends FilterInputStream
  52 {
  53   /**
  54    * The CR octet.
  55    */
  56   public static final int CR = 13;
  57
  58   /**
  59    * The LF octet.
  60    */
  61   public static final int LF = 10;
  62
  63   /**
  64    * Buffer.
  65    */
  66   protected int buf = -1;
  67
  68   /**
  69    * Buffer at time of mark.
  70    */
  71   protected int markBuf = -1;
  72
  73   /**
  74    * Constructs a CR/LF input stream connected to the specified input
  75    * stream.
  76    */
  77   public CRLFInputStream(InputStream in)
  78   {
  79     super(in);
  80   }
  81
  82   /**
  83    * Reads the next byte of data from this input stream.
  84    * Returns -1 if the end of the stream has been reached.
  85    * @exception IOException if an I/O error occurs
  86    */
  87   public int read()
  88     throws IOException
  89   {
  90     int c;
  91     if (buf != -1)
  92       {
  93         c = buf;
  94         buf = -1;
  95         return c;
  96       }
  97     else
  98       {
  99         c = super.read();
 100         if (c == CR)
 101           {
 102             buf = super.read();
 103             if (buf == LF)
 104               {
 105                 c = buf;
 106                 buf = -1;
 107               }
 108           }
 109       }
 110     return c;
 111   }
 112
 113   /**
 114    * Reads up to b.length bytes of data from this input stream into
 115    * an array of bytes.
 116    * Returns -1 if the end of the stream has been reached.
 117    * @exception IOException if an I/O error occurs
 118    */
 119   public int read(byte[] b)
 120     throws IOException
 121   {
 122     return read(b, 0, b.length);
 123   }
 124
 125   /**
 126    * Reads up to len bytes of data from this input stream into an
 127    * array of bytes, starting at the specified offset.
 128    * Returns -1 if the end of the stream has been reached.
 129    * @exception IOException if an I/O error occurs
 130    */
 131   public int read(byte[] b, int off, int len)
 132     throws IOException
 133   {
 134     int shift = 0;
 135     if (buf != -1)
 136       {
 137         // Push buf onto start of byte array
 138         b[off] = (byte) buf;
 139         off++;
 140         len--;
 141         buf = -1;
 142         shift++;
 143       }
 144     int l = super.read(b, off, len);
 145     l = removeCRLF(b, off - shift, l);
 146     return l;
 147   }
 148
 149   /**
 150    * Indicates whether this stream supports the mark and reset methods.
 151    */
 152   public boolean markSupported()
 153   {
 154     return in.markSupported();
 155   }
 156
 157   /**
 158    * Marks the current position in this stream.
 159    */
 160   public void mark(int readlimit)
 161   {
 162     in.mark(readlimit);
 163     markBuf = buf;
 164   }
 165
 166   /**
 167    * Repositions this stream to the position at the time the mark method was
 168    * called.
 169    */
 170   public void reset()
 171     throws IOException
 172   {
 173     in.reset();
 174     buf = markBuf;
 175   }
 176
 177   private int removeCRLF(byte[] b, int off, int len)
 178   {
 179     int end = off + len;
 180     for (int i = off; i < end; i++)
 181       {
 182         if (b[i] == CR)
 183           {
 184             if (i + 1 == end)
 185               {
 186                 // This is the last byte, impossible to determine whether CRLF
 187                 buf = CR;
 188                 len--;
 189               }
 190             else if (b[i + 1] == LF)
 191               {
 192                 // Shift left
 193                 end--;
 194                 for (int j = i; j < end; j++)
 195                   {
 196                     b[j] = b[j + 1];
 197                   }
 198                   len--;
 199                   end = off + len;
 200               }
 201           }
 202       }
 203     return len;
 204   }
 205 }