1 /* DeflateTransformer.java -- 2 Copyright (C) 2003, 2006 Free Software Foundation, Inc. 3 4 This file is a 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 of the License, or (at 9 your option) 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; if not, write to the Free Software 18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19 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 39 package gnu.javax.crypto.assembly; 40 41 import java.util.Map; 42 import java.util.zip.DataFormatException; 43 import java.util.zip.Deflater; 44 import java.util.zip.Inflater; 45 46 /** 47 * A {@link Transformer} Adapter allowing inclusion of a DEFLATE compression 48 * algorithm in an {@link Assembly} chain. The {@link Direction#FORWARD} 49 * transformation is a compression (deflate) of input data, while the 50 * {@link Direction#REVERSED} one is a decompression (inflate) that restores the 51 * original data. 52 * <p> 53 * This {@link Transformer} uses a {@link Deflater} instance to carry on the 54 * compression, and an {@link Inflater} to do the decompression. 55 * <p> 56 * When using such a {@link Transformer}, in an {@link Assembly}, there must 57 * be at least one element behind this instance in the constructed chain; 58 * otherwise, a {@link TransformerException} is thrown at initialisation time. 59 */ 60 class DeflateTransformer 61 extends Transformer 62 { 63 private Deflater compressor; 64 65 private Inflater decompressor; 66 67 private int outputBlockSize = 512; // default zlib buffer size 68 69 private byte[] zlibBuffer; 70 DeflateTransformer()71 DeflateTransformer() 72 { 73 super(); 74 75 } 76 initDelegate(Map attributes)77 void initDelegate(Map attributes) throws TransformerException 78 { 79 if (tail == null) 80 { 81 IllegalStateException cause = new IllegalStateException( 82 "Compression transformer missing its tail!"); 83 throw new TransformerException("initDelegate()", cause); 84 } 85 outputBlockSize = tail.currentBlockSize(); 86 zlibBuffer = new byte[outputBlockSize]; 87 Direction flow = (Direction) attributes.get(DIRECTION); 88 if (flow == Direction.FORWARD) 89 compressor = new Deflater(); 90 else 91 decompressor = new Inflater(); 92 } 93 delegateBlockSize()94 int delegateBlockSize() 95 { 96 return 1; 97 } 98 resetDelegate()99 void resetDelegate() 100 { 101 compressor = null; 102 decompressor = null; 103 outputBlockSize = 1; 104 zlibBuffer = null; 105 } 106 updateDelegate(byte[] in, int offset, int length)107 byte[] updateDelegate(byte[] in, int offset, int length) 108 throws TransformerException 109 { 110 byte[] result; 111 if (wired == Direction.FORWARD) 112 { 113 compressor.setInput(in, offset, length); 114 while (! compressor.needsInput()) 115 compress(); 116 } 117 else // decompression: inflate first and then update tail 118 decompress(in, offset, length); 119 result = inBuffer.toByteArray(); 120 inBuffer.reset(); 121 return result; 122 } 123 lastUpdateDelegate()124 byte[] lastUpdateDelegate() throws TransformerException 125 { 126 // process multiples of blocksize as much as possible 127 if (wired == Direction.FORWARD) // compressing 128 { 129 if (! compressor.finished()) 130 { 131 compressor.finish(); 132 while (! compressor.finished()) 133 compress(); 134 } 135 } 136 else // decompressing 137 { 138 if (! decompressor.finished()) 139 { 140 IllegalStateException cause = new IllegalStateException( 141 "Compression transformer, after last update, must be finished " 142 + "but isn't"); 143 throw new TransformerException("lastUpdateDelegate()", cause); 144 } 145 } 146 byte[] result = inBuffer.toByteArray(); 147 inBuffer.reset(); 148 return result; 149 } 150 compress()151 private void compress() 152 { 153 int len = compressor.deflate(zlibBuffer); 154 if (len > 0) 155 inBuffer.write(zlibBuffer, 0, len); 156 } 157 decompress(byte[] in, int offset, int length)158 private void decompress(byte[] in, int offset, int length) 159 throws TransformerException 160 { 161 decompressor.setInput(in, offset, length); 162 int len = 1; 163 while (len > 0) 164 { 165 try 166 { 167 len = decompressor.inflate(zlibBuffer); 168 } 169 catch (DataFormatException x) 170 { 171 throw new TransformerException("decompress()", x); 172 } 173 if (len > 0) 174 inBuffer.write(zlibBuffer, 0, len); 175 } 176 } 177 } 178