libjava/java/util/zip/InflaterInputStream.java

   1 /* InflaterInputStream.java - Input stream filter for decompressing
   2    Copyright (C) 1999, 2000, 2002, 2003 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 package java.util.zip;
  39
  40 import java.io.FilterInputStream;
  41 import java.io.InputStream;
  42 import java.io.IOException;
  43
  44 /**
  45  * @author Tom Tromey
  46  * @date May 17, 1999
  47  */
  48
  49 /* Written using on-line Java Platform 1.2 API Specification
  50  * and JCL book.
  51  * Believed complete and correct.
  52  */
  53
  54 public class InflaterInputStream extends FilterInputStream
  55 {
  56   protected void fill () throws IOException
  57   {
  58     len = in.read(buf, 0, buf.length);
  59     if (len != -1)
  60       inf.setInput(buf, 0, len);
  61   }
  62
  63   public InflaterInputStream (InputStream in)
  64   {
  65     this (in, new Inflater (), 512);
  66   }
  67
  68   public InflaterInputStream (InputStream in, Inflater infl)
  69   {
  70     this (in, infl, 512);
  71   }
  72
  73   public InflaterInputStream (InputStream in, Inflater infl, int bufsize)
  74   {
  75     super (in);
  76     this.inf = infl;
  77     this.buf = new byte[bufsize];
  78   }
  79
  80   public int read () throws IOException
  81   {
  82     byte[] buf = new byte[1];
  83     int r = read (buf, 0, 1);
  84     if (r != -1)
  85       r = buf[0] & 0xff;
  86     return r;
  87   }
  88
  89   public int read (byte[] buf, int off, int len) throws IOException
  90   {
  91     if (inf == null)
  92       throw new IOException ("stream closed");
  93     if (len == 0)
  94       return 0;
  95     if (inf.finished())
  96       return -1;
  97
  98     int count = 0;
  99     while (count == 0)
 100       {
 101         if (inf.needsInput())
 102           fill ();
 103         try
 104           {
 105             count = inf.inflate(buf, off, len);
 106             if (count == 0)
 107               {
 108                 if (this.len == -1)
 109                   {
 110                     // Couldn't get any more data to feed to the Inflater
 111                     return -1;
 112                   }
 113                 if (inf.needsDictionary())
 114                   throw new ZipException ("Inflater needs Dictionary");
 115               }
 116           }
 117         catch (DataFormatException dfe)
 118           {
 119             throw new ZipException (dfe.getMessage());
 120           }
 121       }
 122     return count;
 123   }
 124
 125   public void close () throws IOException
 126   {
 127     inf = null;
 128     super.close ();
 129   }
 130
 131   public int available () throws IOException
 132   {
 133     // According to the JDK 1.2 docs, this should only ever return 0
 134     // or 1 and should not be relied upon by Java programs.
 135     if (inf == null)
 136       throw new IOException ("stream closed");
 137     return inf.finished () ? 0 : 1;
 138   }
 139
 140   public long skip (long n) throws IOException
 141   {
 142     if (inf == null)
 143       throw new IOException ("stream closed");
 144
 145     if (n == 0)
 146       return 0;
 147
 148     int min = (int) Math.min(n, 1024);
 149     byte[] buf = new byte[min];
 150
 151     long s = 0;
 152     while (n > 0)
 153       {
 154         int r = read (buf, 0, min);
 155         if (r == -1)
 156           break;
 157         n -= r;
 158         s += r;
 159         min = (int) Math.min(n, 1024);
 160       }
 161
 162     return s;
 163   }
 164
 165   // Buffer for delivering uncompressed data to inflater.
 166   protected byte[] buf;
 167
 168   // Inflater used to decompress data.
 169   protected Inflater inf;
 170
 171   // Number of read bytes in buf.
 172   protected int len;
 173 }