001 /* Inflater.java - Decompress a data stream
002 Copyright (C) 1999, 2000, 2001, 2003 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
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012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
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017 along with GNU Classpath; see the file COPYING. If not, write to the
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019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
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031 independent module, the terms and conditions of the license of that
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033 or based on this library. If you modify this library, you may extend
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035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.util.zip;
039
040 import gnu.gcj.RawData;
041
042 /* Written using on-line Java Platform 1.2 API Specification
043 * and JCL book.
044 * Believed complete and correct.
045 */
046
047 /**
048 * Inflater is used to decompress data that has been compressed according
049 * to the "deflate" standard described in rfc1950.
050 *
051 * The usage is as following. First you have to set some input with
052 * <code>setInput()</code>, then inflate() it. If inflate doesn't
053 * inflate any bytes there may be three reasons:
054 * <ul>
055 * <li>needsInput() returns true because the input buffer is empty.
056 * You have to provide more input with <code>setInput()</code>.
057 * NOTE: needsInput() also returns true when, the stream is finished.
058 * </li>
059 * <li>needsDictionary() returns true, you have to provide a preset
060 * dictionary with <code>setDictionary()</code>.</li>
061 * <li>finished() returns true, the inflater has finished.</li>
062 * </ul>
063 * Once the first output byte is produced, a dictionary will not be
064 * needed at a later stage.
065 *
066 * @author John Leuner, Jochen Hoenicke
067 * @author Tom Tromey
068 * @date May 17, 1999
069 * @since JDK 1.1
070 */
071 public class Inflater
072 {
073 // The zlib stream.
074 private RawData zstream;
075
076 // True if finished.
077 private boolean is_finished;
078
079 // True if dictionary needed.
080 private boolean dict_needed;
081
082 /**
083 * Creates a new inflater.
084 */
085 public Inflater ()
086 {
087 this (false);
088 }
089
090 /**
091 * Creates a new inflater.
092 * @param nowrap true if no header and checksum field appears in the
093 * stream. This is used for GZIPed input. For compatibility with
094 * Sun JDK you should provide one byte of input more than needed in
095 * this case.
096 */
097 public Inflater (boolean noHeader)
098 {
099 init (noHeader);
100 }
101
102 /**
103 * Finalizes this object.
104 */
105 protected void finalize ()
106 {
107 end ();
108 }
109
110 /**
111 * Frees all objects allocated by the inflater. There's no reason
112 * to call this, since you can just rely on garbage collection (even
113 * for the Sun implementation). Exists only for compatibility
114 * with Sun's JDK, where the compressor allocates native memory.
115 * If you call any method (even reset) afterwards the behaviour is
116 * <i>undefined</i>.
117 * @deprecated Just clear all references to inflater instead.
118 */
119 public native void end ();
120
121 /**
122 * Returns true, if the inflater has finished. This means, that no
123 * input is needed and no output can be produced.
124 */
125 public synchronized boolean finished ()
126 {
127 return is_finished;
128 }
129
130 /**
131 * Gets the adler checksum. This is either the checksum of all
132 * uncompressed bytes returned by inflate(), or if needsDictionary()
133 * returns true (and thus no output was yet produced) this is the
134 * adler checksum of the expected dictionary.
135 * @returns the adler checksum.
136 */
137 public native int getAdler ();
138
139 /**
140 * Gets the number of unprocessed input. Useful, if the end of the
141 * stream is reached and you want to further process the bytes after
142 * the deflate stream.
143 * @return the number of bytes of the input which were not processed.
144 */
145 public native int getRemaining ();
146
147 /**
148 * Gets the total number of processed compressed input bytes.
149 * @return the total number of bytes of processed input bytes.
150 */
151 public native int getTotalIn ();
152
153 /**
154 * Gets the total number of output bytes returned by inflate().
155 * @return the total number of output bytes.
156 */
157 public native int getTotalOut ();
158
159 /**
160 * Inflates the compressed stream to the output buffer. If this
161 * returns 0, you should check, whether needsDictionary(),
162 * needsInput() or finished() returns true, to determine why no
163 * further output is produced.
164 * @param buffer the output buffer.
165 * @return the number of bytes written to the buffer, 0 if no further
166 * output can be produced.
167 * @exception DataFormatException if deflated stream is invalid.
168 * @exception IllegalArgumentException if buf has length 0.
169 */
170 public int inflate (byte[] buf) throws DataFormatException
171 {
172 return inflate (buf, 0, buf.length);
173 }
174
175 /**
176 * Inflates the compressed stream to the output buffer. If this
177 * returns 0, you should check, whether needsDictionary(),
178 * needsInput() or finished() returns true, to determine why no
179 * further output is produced.
180 * @param buffer the output buffer.
181 * @param off the offset into buffer where the output should start.
182 * @param len the maximum length of the output.
183 * @return the number of bytes written to the buffer, 0 if no further
184 * output can be produced.
185 * @exception DataFormatException if deflated stream is invalid.
186 * @exception IndexOutOfBoundsException if the off and/or len are wrong.
187 */
188 public native int inflate (byte[] buf, int off, int len)
189 throws DataFormatException;
190
191 private native void init (boolean noHeader);
192
193 /**
194 * Returns true, if a preset dictionary is needed to inflate the input.
195 */
196 public synchronized boolean needsDictionary ()
197 {
198 return dict_needed;
199 }
200
201 /**
202 * Returns true, if the input buffer is empty.
203 * You should then call setInput(). <br>
204 *
205 * <em>NOTE</em>: This method also returns true when the stream is finished.
206 */
207 public synchronized boolean needsInput ()
208 {
209 return getRemaining () == 0;
210 }
211
212 /**
213 * Resets the inflater so that a new stream can be decompressed. All
214 * pending input and output will be discarded.
215 */
216 public native void reset ();
217
218 /**
219 * Sets the preset dictionary. This should only be called, if
220 * needsDictionary() returns true and it should set the same
221 * dictionary, that was used for deflating. The getAdler()
222 * function returns the checksum of the dictionary needed.
223 * @param buffer the dictionary.
224 * @exception IllegalStateException if no dictionary is needed.
225 * @exception IllegalArgumentException if the dictionary checksum is
226 * wrong.
227 */
228 public void setDictionary (byte[] buf)
229 {
230 setDictionary (buf, 0, buf.length);
231 }
232
233 /**
234 * Sets the preset dictionary. This should only be called, if
235 * needsDictionary() returns true and it should set the same
236 * dictionary, that was used for deflating. The getAdler()
237 * function returns the checksum of the dictionary needed.
238 * @param buffer the dictionary.
239 * @param off the offset into buffer where the dictionary starts.
240 * @param len the length of the dictionary.
241 * @exception IllegalStateException if no dictionary is needed.
242 * @exception IllegalArgumentException if the dictionary checksum is
243 * wrong.
244 * @exception IndexOutOfBoundsException if the off and/or len are wrong.
245 */
246 public native void setDictionary (byte[] buf, int off, int len);
247
248 /**
249 * Sets the input. This should only be called, if needsInput()
250 * returns true.
251 * @param buffer the input.
252 * @exception IllegalStateException if no input is needed.
253 */
254 public void setInput (byte[] buf)
255 {
256 setInput (buf, 0, buf.length);
257 }
258
259 /**
260 * Sets the input. This should only be called, if needsInput()
261 * returns true.
262 * @param buffer the input.
263 * @param off the offset into buffer where the input starts.
264 * @param len the length of the input.
265 * @exception IllegalStateException if no input is needed.
266 * @exception IndexOutOfBoundsException if the off and/or len are wrong.
267 */
268 public native void setInput (byte[] buf, int off, int len);
269 }