libjava/java/util/zip/InflaterInputStream.java

   1 /* InflaterInputStream.java - Input stream filter for decompressing
   2    Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GNU Classpath.
   6
   7 GNU Classpath 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, or (at your option)
  10 any later version.
  11
  12 GNU Classpath is distributed in the hope that it will be useful, but
  13 WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Classpath; see the file COPYING.  If not, write to the
  19 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  20 02111-1307 USA.
  21
  22 Linking this library statically or dynamically with other modules is
  23 making a combined work based on this library.  Thus, the terms and
  24 conditions of the GNU General Public License cover the whole
  25 combination.
  26
  27 As a special exception, the copyright holders of this library give you
  28 permission to link this library with independent modules to produce an
  29 executable, regardless of the license terms of these independent
  30 modules, and to copy and distribute the resulting executable under
  31 terms of your choice, provided that you also meet, for each linked
  32 independent module, the terms and conditions of the license of that
  33 module.  An independent module is a module which is not derived from
  34 or based on this library.  If you modify this library, you may extend
  35 this exception to your version of the library, but you are not
  36 obligated to do so.  If you do not wish to do so, delete this
  37 exception statement from your version. */
  38
  39
  40 package java.util.zip;
  41
  42 import java.io.FilterInputStream;
  43 import java.io.IOException;
  44 import java.io.InputStream;
  45
  46 /**
  47  * This filter stream is used to decompress data compressed in the "deflate"
  48  * format. The "deflate" format is described in RFC 1951.
  49  *
  50  * This stream may form the basis for other decompression filters, such
  51  * as the <code>GZIPInputStream</code>.
  52  *
  53  * @author John Leuner
  54  * @author Tom Tromey
  55  * @since 1.1
  56  */
  57 public class InflaterInputStream extends FilterInputStream
  58 {
  59   /**
  60    * Decompressor for this filter
  61    */
  62   protected Inflater inf;
  63
  64   /**
  65    * Byte array used as a buffer
  66    */
  67   protected byte[] buf;
  68
  69   /**
  70    * Size of buffer
  71    */
  72   protected int len;
  73
  74   // We just use this if we are decoding one byte at a time with the
  75   // read() call.
  76   private byte[] onebytebuffer = new byte[1];
  77
  78   /**
  79    * Create an InflaterInputStream with the default decompresseor
  80    * and a default buffer size.
  81    *
  82    * @param in the InputStream to read bytes from
  83    */
  84   public InflaterInputStream(InputStream in)
  85   {
  86     this(in, new Inflater(), 4096);
  87   }
  88
  89   /**
  90    * Create an InflaterInputStream with the specified decompresseor
  91    * and a default buffer size.
  92    *
  93    * @param in the InputStream to read bytes from
  94    * @param inf the decompressor used to decompress data read from in
  95    */
  96   public InflaterInputStream(InputStream in, Inflater inf)
  97   {
  98     this(in, inf, 4096);
  99   }
 100
 101   /**
 102    * Create an InflaterInputStream with the specified decompresseor
 103    * and a specified buffer size.
 104    *
 105    * @param in the InputStream to read bytes from
 106    * @param inf the decompressor used to decompress data read from in
 107    * @param size size of the buffer to use
 108    */
 109   public InflaterInputStream(InputStream in, Inflater inf, int size)
 110   {
 111     super(in);
 112
 113     if (in == null)
 114       throw new NullPointerException("in may not be null");
 115     if (inf == null)
 116       throw new NullPointerException("inf may not be null");
 117     if (size < 0)
 118       throw new IllegalArgumentException("size may not be negative");
 119
 120     this.inf = inf;
 121     this.buf = new byte [size];
 122   }
 123
 124   /**
 125    * Returns 0 once the end of the stream (EOF) has been reached.
 126    * Otherwise returns 1.
 127    */
 128   public int available() throws IOException
 129   {
 130     // According to the JDK 1.2 docs, this should only ever return 0
 131     // or 1 and should not be relied upon by Java programs.
 132     if (inf == null)
 133       throw new IOException("stream closed");
 134     return inf.finished() ? 0 : 1;
 135   }
 136
 137   /**
 138    * Closes the input stream
 139    */
 140   public synchronized void close() throws IOException
 141   {
 142     inf = null;
 143     super.close();
 144   }
 145
 146   /**
 147    * Fills the buffer with more data to decompress.
 148    */
 149   protected void fill() throws IOException
 150   {
 151     if (in == null)
 152       throw new ZipException ("InflaterInputStream is closed");
 153
 154     len = in.read(buf, 0, buf.length);
 155
 156     if (len >= 0)
 157       inf.setInput(buf, 0, len);
 158   }
 159
 160   /**
 161    * Reads one byte of decompressed data.
 162    *
 163    * The byte is in the lower 8 bits of the int.
 164    */
 165   public int read() throws IOException
 166   {
 167     int nread = read(onebytebuffer, 0, 1);
 168     if (nread > 0)
 169       return onebytebuffer[0] & 0xff;
 170     return -1;
 171   }
 172
 173   /**
 174    * Decompresses data into the byte array
 175    *
 176    * @param b the array to read and decompress data into
 177    * @param off the offset indicating where the data should be placed
 178    * @param len the number of bytes to decompress
 179    */
 180   public int read(byte[] b, int off, int len) throws IOException
 181   {
 182     if (inf == null)
 183       throw new IOException("stream closed");
 184     if (len == 0)
 185       return 0;
 186     if (inf.finished())
 187       return -1;
 188
 189     int count = 0;
 190     while (count == 0)
 191       {
 192         if (inf.needsInput())
 193           fill();
 194
 195         try
 196           {
 197             count = inf.inflate(b, off, len);
 198             if (count == 0)
 199               {
 200                 if (this.len == -1)
 201                   {
 202                     // Couldn't get any more data to feed to the Inflater
 203                     return -1;
 204                   }
 205                 if (inf.needsDictionary())
 206                   throw new ZipException("Inflater needs Dictionary");
 207               }
 208           }
 209         catch (DataFormatException dfe)
 210           {
 211             throw new ZipException(dfe.getMessage());
 212           }
 213       }
 214     return count;
 215   }
 216
 217   /**
 218    * Skip specified number of bytes of uncompressed data
 219    *
 220    * @param n number of bytes to skip
 221    */
 222   public long skip(long n) throws IOException
 223   {
 224     if (inf == null)
 225       throw new IOException("stream closed");
 226     if (n < 0)
 227       throw new IllegalArgumentException();
 228
 229     if (n == 0)
 230       return 0;
 231
 232     int buflen = (int) Math.min(n, 2048);
 233     byte[] tmpbuf = new byte[buflen];
 234
 235     long skipped = 0L;
 236     while (n > 0L)
 237       {
 238         int numread = read(tmpbuf, 0, buflen);
 239         if (numread <= 0)
 240           break;
 241         n -= numread;
 242         skipped += numread;
 243         buflen = (int) Math.min(n, 2048);
 244       }
 245
 246     return skipped;
 247  }
 248
 249   public boolean markSupported()
 250   {
 251     return false;
 252   }
 253
 254   public void mark(int readLimit)
 255   {
 256   }
 257
 258   public void reset() throws IOException
 259   {
 260     throw new IOException("reset not supported");
 261   }
 262 }