1 /* Inflater.java - Decompress a data stream 2 Copyright (C) 1999, 2000, 2001, 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 gnu.gcj.RawData; 41 42 /* Written using on-line Java Platform 1.2 API Specification 43 * and JCL book. 44 * Believed complete and correct. 45 */ 46 47 /** 48 * Inflater is used to decompress data that has been compressed according 49 * to the "deflate" standard described in rfc1950. 50 * 51 * The usage is as following. First you have to set some input with 52 * <code>setInput()</code>, then inflate() it. If inflate doesn't 53 * inflate any bytes there may be three reasons: 54 * <ul> 55 * <li>needsInput() returns true because the input buffer is empty. 56 * You have to provide more input with <code>setInput()</code>. 57 * NOTE: needsInput() also returns true when, the stream is finished. 58 * </li> 59 * <li>needsDictionary() returns true, you have to provide a preset 60 * dictionary with <code>setDictionary()</code>.</li> 61 * <li>finished() returns true, the inflater has finished.</li> 62 * </ul> 63 * Once the first output byte is produced, a dictionary will not be 64 * needed at a later stage. 65 * 66 * @author John Leuner, Jochen Hoenicke 67 * @author Tom Tromey 68 * @date May 17, 1999 69 * @since JDK 1.1 70 */ 71 public class Inflater 72 { 73 // The zlib stream. 74 private RawData zstream; 75 76 // True if finished. 77 private boolean is_finished; 78 79 // True if dictionary needed. 80 private boolean dict_needed; 81 82 /** 83 * Creates a new inflater. 84 */ Inflater()85 public Inflater () 86 { 87 this (false); 88 } 89 90 /** 91 * Creates a new inflater. 92 * @param nowrap true if no header and checksum field appears in the 93 * stream. This is used for GZIPed input. For compatibility with 94 * Sun JDK you should provide one byte of input more than needed in 95 * this case. 96 */ Inflater(boolean noHeader)97 public Inflater (boolean noHeader) 98 { 99 init (noHeader); 100 } 101 102 /** 103 * Finalizes this object. 104 */ finalize()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 */ end()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 */ finished()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 */ getAdler()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 */ getRemaining()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 */ getTotalIn()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 */ getTotalOut()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 */ inflate(byte[] buf)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 */ inflate(byte[] buf, int off, int len)188 public native int inflate (byte[] buf, int off, int len) 189 throws DataFormatException; 190 init(boolean noHeader)191 private native void init (boolean noHeader); 192 193 /** 194 * Returns true, if a preset dictionary is needed to inflate the input. 195 */ needsDictionary()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 */ needsInput()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 */ reset()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 */ setDictionary(byte[] buf)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 */ setDictionary(byte[] buf, int off, int len)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 */ setInput(byte[] buf)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 */ setInput(byte[] buf, int off, int len)268 public native void setInput (byte[] buf, int off, int len); 269 } 270