001 /* InflaterInputStream.java - Input stream filter for decompressing
002 Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2006
003 Free Software Foundation, Inc.
004
005 This file is part of GNU Classpath.
006
007 GNU Classpath is free software; you can redistribute it and/or modify
008 it under the terms of the GNU General Public License as published by
009 the Free Software Foundation; either version 2, or (at your option)
010 any later version.
011
012 GNU Classpath is distributed in the hope that it will be useful, but
013 WITHOUT ANY WARRANTY; without even the implied warranty of
014 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015 General Public License for more details.
016
017 You should have received a copy of the GNU General Public License
018 along with GNU Classpath; see the file COPYING. If not, write to the
019 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
020 02110-1301 USA.
021
022 Linking this library statically or dynamically with other modules is
023 making a combined work based on this library. Thus, the terms and
024 conditions of the GNU General Public License cover the whole
025 combination.
026
027 As a special exception, the copyright holders of this library give you
028 permission to link this library with independent modules to produce an
029 executable, regardless of the license terms of these independent
030 modules, and to copy and distribute the resulting executable under
031 terms of your choice, provided that you also meet, for each linked
032 independent module, the terms and conditions of the license of that
033 module. An independent module is a module which is not derived from
034 or based on this library. If you modify this library, you may extend
035 this exception to your version of the library, but you are not
036 obligated to do so. If you do not wish to do so, delete this
037 exception statement from your version. */
038
039
040 package java.util.zip;
041
042 import java.io.FilterInputStream;
043 import java.io.IOException;
044 import java.io.InputStream;
045
046 /**
047 * This filter stream is used to decompress data compressed in the "deflate"
048 * format. The "deflate" format is described in RFC 1951.
049 *
050 * This stream may form the basis for other decompression filters, such
051 * as the <code>GZIPInputStream</code>.
052 *
053 * @author John Leuner
054 * @author Tom Tromey
055 * @since 1.1
056 */
057 public class InflaterInputStream extends FilterInputStream
058 {
059 /**
060 * Decompressor for this filter
061 */
062 protected Inflater inf;
063
064 /**
065 * Byte array used as a buffer
066 */
067 protected byte[] buf;
068
069 /**
070 * Size of buffer
071 */
072 protected int len;
073
074 // We just use this if we are decoding one byte at a time with the
075 // read() call.
076 private byte[] onebytebuffer = new byte[1];
077
078 /**
079 * Create an InflaterInputStream with the default decompresseor
080 * and a default buffer size.
081 *
082 * @param in the InputStream to read bytes from
083 */
084 public InflaterInputStream(InputStream in)
085 {
086 this(in, new Inflater(), 4096);
087 }
088
089 /**
090 * Create an InflaterInputStream with the specified decompresseor
091 * and a default buffer size.
092 *
093 * @param in the InputStream to read bytes from
094 * @param inf the decompressor used to decompress data read from in
095 */
096 public InflaterInputStream(InputStream in, Inflater inf)
097 {
098 this(in, inf, 4096);
099 }
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 if (in != null)
143 in.close();
144 in = null;
145 }
146
147 /**
148 * Fills the buffer with more data to decompress.
149 */
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 */
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 */
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 */
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
252 public boolean markSupported()
253 {
254 return false;
255 }
256
257 public void mark(int readLimit)
258 {
259 }
260
261 public void reset() throws IOException
262 {
263 throw new IOException("reset not supported");
264 }
265 }