1 /* InflaterInputStream.java - Input stream filter for decompressing
2    Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2006
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., 51 Franklin Street, Fifth Floor, Boston, MA
20 02110-1301 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    */
InflaterInputStream(InputStream in)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    */
InflaterInputStream(InputStream in, Inflater inf)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    */
InflaterInputStream(InputStream in, Inflater inf, int size)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    */
available()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    */
close()140   public synchronized void close() throws IOException
141   {
142     if (in != null)
143       in.close();
144     in = null;
145   }
146 
147   /**
148    * Fills the buffer with more data to decompress.
149    */
fill()150   protected void fill() throws IOException
151   {
152     if (in == null)
153       throw new ZipException ("InflaterInputStream is closed");
154 
155     len = in.read(buf, 0, buf.length);
156 
157     if (len < 0)
158       throw new ZipException("Deflated stream ends early.");
159 
160     inf.setInput(buf, 0, len);
161   }
162 
163   /**
164    * Reads one byte of decompressed data.
165    *
166    * The byte is in the lower 8 bits of the int.
167    */
read()168   public int read() throws IOException
169   {
170     int nread = read(onebytebuffer, 0, 1);
171     if (nread > 0)
172       return onebytebuffer[0] & 0xff;
173     return -1;
174   }
175 
176   /**
177    * Decompresses data into the byte array
178    *
179    * @param b the array to read and decompress data into
180    * @param off the offset indicating where the data should be placed
181    * @param len the number of bytes to decompress
182    */
read(byte[] b, int off, int len)183   public int read(byte[] b, int off, int len) throws IOException
184   {
185     if (inf == null)
186       throw new IOException("stream closed");
187     if (len == 0)
188       return 0;
189     if (inf.finished())
190       return -1;
191 
192     int count = 0;
193     while (count == 0)
194       {
195         if (inf.needsInput())
196           fill();
197 
198         try
199           {
200             count = inf.inflate(b, off, len);
201             if (count == 0)
202               {
203                 if (this.len == -1)
204                   {
205                     // Couldn't get any more data to feed to the Inflater
206                     return -1;
207                   }
208                 if (inf.needsDictionary())
209                   throw new ZipException("Inflater needs Dictionary");
210               }
211           }
212         catch (DataFormatException dfe)
213           {
214             throw new ZipException(dfe.getMessage());
215           }
216       }
217     return count;
218   }
219 
220   /**
221    * Skip specified number of bytes of uncompressed data
222    *
223    * @param n number of bytes to skip
224    */
skip(long n)225   public long skip(long n) throws IOException
226   {
227     if (inf == null)
228       throw new IOException("stream closed");
229     if (n < 0)
230       throw new IllegalArgumentException();
231 
232     if (n == 0)
233       return 0;
234 
235     int buflen = (int) Math.min(n, 2048);
236     byte[] tmpbuf = new byte[buflen];
237 
238     long skipped = 0L;
239     while (n > 0L)
240       {
241         int numread = read(tmpbuf, 0, buflen);
242         if (numread <= 0)
243           break;
244         n -= numread;
245         skipped += numread;
246         buflen = (int) Math.min(n, 2048);
247       }
248 
249     return skipped;
250  }
251 
markSupported()252   public boolean markSupported()
253   {
254     return false;
255   }
256 
mark(int readLimit)257   public void mark(int readLimit)
258   {
259   }
260 
reset()261   public void reset() throws IOException
262   {
263     throw new IOException("reset not supported");
264   }
265 }
266