InflaterInputStream.java revision 49965c1dc9da104344f4893a05e45795a5740d20
1/* 2 * Copyright (C) 2014 The Android Open Source Project 3 * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. Oracle designates this 9 * particular file as subject to the "Classpath" exception as provided 10 * by Oracle in the LICENSE file that accompanied this code. 11 * 12 * This code is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 * version 2 for more details (a copy is included in the LICENSE file that 16 * accompanied this code). 17 * 18 * You should have received a copy of the GNU General Public License version 19 * 2 along with this work; if not, write to the Free Software Foundation, 20 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 21 * 22 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 23 * or visit www.oracle.com if you need additional information or have any 24 * questions. 25 */ 26 27package java.util.zip; 28 29import java.io.FilterInputStream; 30import java.io.InputStream; 31import java.io.IOException; 32import java.io.EOFException; 33 34/** 35 * This class implements a stream filter for uncompressing data in the 36 * "deflate" compression format. It is also used as the basis for other 37 * decompression filters, such as GZIPInputStream. 38 * 39 * @see Inflater 40 * @author David Connelly 41 */ 42public 43class InflaterInputStream extends FilterInputStream { 44 /** 45 * Decompressor for this stream. 46 */ 47 protected Inflater inf; 48 49 /** 50 * Input buffer for decompression. 51 */ 52 protected byte[] buf; 53 54 /** 55 * Length of input buffer. 56 */ 57 protected int len; 58 59 // Android-changed: closed is now protected. 60 protected boolean closed = false; 61 62 // this flag is set to true after EOF has reached 63 private boolean reachEOF = false; 64 65 /** 66 * Check to make sure that this stream has not been closed 67 */ 68 private void ensureOpen() throws IOException { 69 if (closed) { 70 throw new IOException("Stream closed"); 71 } 72 } 73 74 75 /** 76 * Creates a new input stream with the specified decompressor and 77 * buffer size. 78 * @param in the input stream 79 * @param inf the decompressor ("inflater") 80 * @param size the input buffer size 81 * @exception IllegalArgumentException if size is <= 0 82 */ 83 public InflaterInputStream(InputStream in, Inflater inf, int size) { 84 super(in); 85 if (in == null || inf == null) { 86 throw new NullPointerException(); 87 } else if (size <= 0) { 88 throw new IllegalArgumentException("buffer size <= 0"); 89 } 90 this.inf = inf; 91 buf = new byte[size]; 92 } 93 94 /** 95 * Creates a new input stream with the specified decompressor and a 96 * default buffer size. 97 * @param in the input stream 98 * @param inf the decompressor ("inflater") 99 */ 100 public InflaterInputStream(InputStream in, Inflater inf) { 101 this(in, inf, 512); 102 } 103 104 /** 105 * Creates a new input stream with a default decompressor and buffer size. 106 * @param in the input stream 107 */ 108 public InflaterInputStream(InputStream in) { 109 this(in, new Inflater()); 110 } 111 112 private byte[] singleByteBuf = new byte[1]; 113 114 /** 115 * Reads a byte of uncompressed data. This method will block until 116 * enough input is available for decompression. 117 * @return the byte read, or -1 if end of compressed input is reached 118 * @exception IOException if an I/O error has occurred 119 */ 120 public int read() throws IOException { 121 ensureOpen(); 122 return read(singleByteBuf, 0, 1) == -1 ? -1 : singleByteBuf[0] & 0xff; 123 } 124 125 /** 126 * Reads uncompressed data into an array of bytes. If <code>len</code> is not 127 * zero, the method will block until some input can be decompressed; otherwise, 128 * no bytes are read and <code>0</code> is returned. 129 * @param b the buffer into which the data is read 130 * @param off the start offset in the destination array <code>b</code> 131 * @param len the maximum number of bytes read 132 * @return the actual number of bytes read, or -1 if the end of the 133 * compressed input is reached or a preset dictionary is needed 134 * @exception NullPointerException If <code>b</code> is <code>null</code>. 135 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 136 * <code>len</code> is negative, or <code>len</code> is greater than 137 * <code>b.length - off</code> 138 * @exception ZipException if a ZIP format error has occurred 139 * @exception IOException if an I/O error has occurred 140 */ 141 public int read(byte[] b, int off, int len) throws IOException { 142 ensureOpen(); 143 if (b == null) { 144 throw new NullPointerException(); 145 } else if (off < 0 || len < 0 || len > b.length - off) { 146 throw new IndexOutOfBoundsException(); 147 } else if (len == 0) { 148 return 0; 149 } 150 try { 151 int n; 152 while ((n = inf.inflate(b, off, len)) == 0) { 153 if (inf.finished() || inf.needsDictionary()) { 154 reachEOF = true; 155 return -1; 156 } 157 if (inf.needsInput()) { 158 fill(); 159 } 160 } 161 162 // Android changed : Eagerly set reachEOF. 163 if (inf.finished()) { 164 reachEOF = true; 165 } 166 167 return n; 168 } catch (DataFormatException e) { 169 String s = e.getMessage(); 170 throw new ZipException(s != null ? s : "Invalid ZLIB data format"); 171 } 172 } 173 174 /** 175 * Returns 0 after EOF has been reached, otherwise always return 1. 176 * <p> 177 * Programs should not count on this method to return the actual number 178 * of bytes that could be read without blocking. 179 * 180 * @return 1 before EOF and 0 after EOF. 181 * @exception IOException if an I/O error occurs. 182 * 183 */ 184 public int available() throws IOException { 185 ensureOpen(); 186 if (reachEOF) { 187 return 0; 188 } else { 189 return 1; 190 } 191 } 192 193 private byte[] b = new byte[512]; 194 195 /** 196 * Skips specified number of bytes of uncompressed data. 197 * @param n the number of bytes to skip 198 * @return the actual number of bytes skipped. 199 * @exception IOException if an I/O error has occurred 200 * @exception IllegalArgumentException if n < 0 201 */ 202 public long skip(long n) throws IOException { 203 if (n < 0) { 204 throw new IllegalArgumentException("negative skip length"); 205 } 206 ensureOpen(); 207 int max = (int)Math.min(n, Integer.MAX_VALUE); 208 int total = 0; 209 while (total < max) { 210 int len = max - total; 211 if (len > b.length) { 212 len = b.length; 213 } 214 len = read(b, 0, len); 215 if (len == -1) { 216 reachEOF = true; 217 break; 218 } 219 total += len; 220 } 221 return total; 222 } 223 224 /** 225 * Closes this input stream and releases any system resources associated 226 * with the stream. 227 * @exception IOException if an I/O error has occurred 228 */ 229 public void close() throws IOException { 230 if (!closed) { 231 inf.end(); 232 in.close(); 233 closed = true; 234 } 235 } 236 237 /** 238 * Fills input buffer with more data to decompress. 239 * @exception IOException if an I/O error has occurred 240 */ 241 protected void fill() throws IOException { 242 ensureOpen(); 243 len = in.read(buf, 0, buf.length); 244 if (len == -1) { 245 throw new EOFException("Unexpected end of ZLIB input stream"); 246 } 247 inf.setInput(buf, 0, len); 248 } 249 250 /** 251 * Tests if this input stream supports the <code>mark</code> and 252 * <code>reset</code> methods. The <code>markSupported</code> 253 * method of <code>InflaterInputStream</code> returns 254 * <code>false</code>. 255 * 256 * @return a <code>boolean</code> indicating if this stream type supports 257 * the <code>mark</code> and <code>reset</code> methods. 258 * @see java.io.InputStream#mark(int) 259 * @see java.io.InputStream#reset() 260 */ 261 public boolean markSupported() { 262 return false; 263 } 264 265 /** 266 * Marks the current position in this input stream. 267 * 268 * <p> The <code>mark</code> method of <code>InflaterInputStream</code> 269 * does nothing. 270 * 271 * @param readlimit the maximum limit of bytes that can be read before 272 * the mark position becomes invalid. 273 * @see java.io.InputStream#reset() 274 */ 275 public synchronized void mark(int readlimit) { 276 } 277 278 /** 279 * Repositions this stream to the position at the time the 280 * <code>mark</code> method was last called on this input stream. 281 * 282 * <p> The method <code>reset</code> for class 283 * <code>InflaterInputStream</code> does nothing except throw an 284 * <code>IOException</code>. 285 * 286 * @exception IOException if this method is invoked. 287 * @see java.io.InputStream#mark(int) 288 * @see java.io.IOException 289 */ 290 public synchronized void reset() throws IOException { 291 throw new IOException("mark/reset not supported"); 292 } 293} 294