Source for gnu.inet.util.CRLFInputStream

   1: /*
   2:  * CRLFInputStream.java
   3:  * Copyright (C) 2002 The Free Software Foundation
   4:  * 
   5:  * This file is part of GNU inetlib, a library.
   6:  * 
   7:  * GNU inetlib is free software; you can redistribute it and/or modify
   8:  * it under the terms of the GNU General Public License as published by
   9:  * the Free Software Foundation; either version 2 of the License, or
  10:  * (at your option) any later version.
  11:  * 
  12:  * GNU inetlib is distributed in the hope that it will be useful,
  13:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15:  * GNU General Public License for more details.
  16:  * 
  17:  * You should have received a copy of the GNU General Public License
  18:  * along with this library; if not, write to the Free Software
  19:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  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:  * obliged to do so.  If you do not wish to do so, delete this
  36:  * exception statement from your version.
  37:  */
  38: 
  39: package gnu.inet.util;
  40: 
  41: import java.io.BufferedInputStream;
  42: import java.io.FilterInputStream;
  43: import java.io.InputStream;
  44: import java.io.IOException;
  45: 
  46: /**
  47:  * An input stream that filters out CR/LF pairs into LFs.
  48:  *
  49:  * @author <a href="mailto:dog@gnu.org">Chris Burdess</a>
  50:  */
  51: public class CRLFInputStream
  52:   extends FilterInputStream
  53: {
  54: 
  55:   /**
  56:    * The CR octet.
  57:    */
  58:   public static final int CR = 13;
  59: 
  60:   /**
  61:    * The LF octet.
  62:    */
  63:   public static final int LF = 10;
  64: 
  65:   private boolean doReset;
  66: 
  67:   /**
  68:    * Constructs a CR/LF input stream connected to the specified input
  69:    * stream.
  70:    */
  71:   public CRLFInputStream(InputStream in)
  72:   {
  73:     super(in.markSupported() ? in : new BufferedInputStream(in));
  74:   }
  75: 
  76:   /**
  77:    * Reads the next byte of data from this input stream.
  78:    * Returns -1 if the end of the stream has been reached.
  79:    * @exception IOException if an I/O error occurs
  80:    */
  81:   public int read()
  82:     throws IOException
  83:   {
  84:     int c = in.read();
  85:     if (c == CR)
  86:       {
  87:         in.mark(1);
  88:         int d = in.read();
  89:         if (d == LF)
  90:           {
  91:             c = d;
  92:           }
  93:         else
  94:           {
  95:             in.reset();
  96:           }
  97:       }
  98:     return c;
  99:   }
 100:   
 101:   /**
 102:    * Reads up to b.length bytes of data from this input stream into
 103:    * an array of bytes.
 104:    * Returns -1 if the end of the stream has been reached.
 105:    * @exception IOException if an I/O error occurs
 106:    */
 107:   public int read(byte[] b)
 108:     throws IOException
 109:   {
 110:     return read(b, 0, b.length);
 111:   }
 112: 
 113:   /**
 114:    * Reads up to len bytes of data from this input stream into an
 115:    * array of bytes, starting at the specified offset.
 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, int off, int len)
 120:     throws IOException
 121:   {
 122:     in.mark(len + 1);
 123:     int l = in.read(b, off, len);
 124:     if (l > 0)
 125:       {
 126:         int i = indexOfCRLF(b, off, l);
 127:         if (doReset)
 128:           {
 129:             in.reset();
 130:             if (i != -1)
 131:               {
 132:                 l = in.read(b, off, i + 1); // read to CR
 133:                 in.read(); // skip LF
 134:                 b[i] = LF; // fix CR as LF
 135:               }
 136:             else
 137:               {
 138:                 l = in.read(b, off, len); // CR(s) but no LF
 139:               }
 140:           }
 141:       }
 142:     return l;
 143:   }
 144: 
 145:   private int indexOfCRLF(byte[] b, int off, int len)
 146:     throws IOException
 147:   {
 148:     doReset = false;
 149:     int lm1 = len - 1;
 150:     for (int i = off; i < len; i++)
 151:       {
 152:         if (b[i] == CR)
 153:           {
 154:             int d;
 155:             if (i == lm1)
 156:               {
 157:                 d = in.read();
 158:                 doReset = true;
 159:               }
 160:             else
 161:               {
 162:                 d = b[i + 1];
 163:               }
 164:             if (d == LF)
 165:               {
 166:                 doReset = true;
 167:                 return i;
 168:               }
 169:           }
 170:       }
 171:     return -1;
 172:   }
 173: 
 174: }