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