1 /* 2 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.util.zip; 27 28 import java.io.SequenceInputStream; 29 import java.io.ByteArrayInputStream; 30 import java.io.FilterInputStream; 31 import java.io.InputStream; 32 import java.io.IOException; 33 import java.io.EOFException; 34 35 /** 36 * This class implements a stream filter for reading compressed data in 37 * the GZIP file format. 38 * 39 * @see InflaterInputStream 40 * @author David Connelly 41 * 42 */ 43 public 44 class GZIPInputStream extends InflaterInputStream { 45 /** 46 * CRC-32 for uncompressed data. 47 */ 48 protected CRC32 crc = new CRC32(); 49 50 /** 51 * Indicates end of input stream. 52 */ 53 protected boolean eos; 54 55 private boolean closed = false; 56 57 /** 58 * Check to make sure that this stream has not been closed 59 */ ensureOpen()60 private void ensureOpen() throws IOException { 61 if (closed) { 62 throw new IOException("Stream closed"); 63 } 64 } 65 66 /** 67 * Creates a new input stream with the specified buffer size. 68 * @param in the input stream 69 * @param size the input buffer size 70 * 71 * @exception ZipException if a GZIP format error has occurred or the 72 * compression method used is unsupported 73 * @exception IOException if an I/O error has occurred 74 * @exception IllegalArgumentException if {@code size <= 0} 75 */ GZIPInputStream(InputStream in, int size)76 public GZIPInputStream(InputStream in, int size) throws IOException { 77 super(in, new Inflater(true), size); 78 // Android-changed: Unconditionally close external inflaters (b/26462400) 79 // usesDefaultInflater = true; 80 readHeader(in); 81 } 82 83 /** 84 * Creates a new input stream with a default buffer size. 85 * @param in the input stream 86 * 87 * @exception ZipException if a GZIP format error has occurred or the 88 * compression method used is unsupported 89 * @exception IOException if an I/O error has occurred 90 */ GZIPInputStream(InputStream in)91 public GZIPInputStream(InputStream in) throws IOException { 92 this(in, 512); 93 } 94 95 /** 96 * Reads uncompressed data into an array of bytes. If <code>len</code> is not 97 * zero, the method will block until some input can be decompressed; otherwise, 98 * no bytes are read and <code>0</code> is returned. 99 * @param buf the buffer into which the data is read 100 * @param off the start offset in the destination array <code>b</code> 101 * @param len the maximum number of bytes read 102 * @return the actual number of bytes read, or -1 if the end of the 103 * compressed input stream is reached 104 * 105 * @exception NullPointerException If <code>buf</code> is <code>null</code>. 106 * @exception IndexOutOfBoundsException If <code>off</code> is negative, 107 * <code>len</code> is negative, or <code>len</code> is greater than 108 * <code>buf.length - off</code> 109 * @exception ZipException if the compressed input data is corrupt. 110 * @exception IOException if an I/O error has occurred. 111 * 112 */ read(byte[] buf, int off, int len)113 public int read(byte[] buf, int off, int len) throws IOException { 114 ensureOpen(); 115 if (eos) { 116 return -1; 117 } 118 int n = super.read(buf, off, len); 119 if (n == -1) { 120 if (readTrailer()) 121 eos = true; 122 else 123 return this.read(buf, off, len); 124 } else { 125 crc.update(buf, off, n); 126 } 127 return n; 128 } 129 130 /** 131 * Closes this input stream and releases any system resources associated 132 * with the stream. 133 * @exception IOException if an I/O error has occurred 134 */ close()135 public void close() throws IOException { 136 if (!closed) { 137 super.close(); 138 eos = true; 139 closed = true; 140 } 141 } 142 143 /** 144 * GZIP header magic number. 145 */ 146 public final static int GZIP_MAGIC = 0x8b1f; 147 148 /* 149 * File header flags. 150 */ 151 private final static int FTEXT = 1; // Extra text 152 private final static int FHCRC = 2; // Header CRC 153 private final static int FEXTRA = 4; // Extra field 154 private final static int FNAME = 8; // File name 155 private final static int FCOMMENT = 16; // File comment 156 157 /* 158 * Reads GZIP member header and returns the total byte number 159 * of this member header. 160 */ readHeader(InputStream this_in)161 private int readHeader(InputStream this_in) throws IOException { 162 CheckedInputStream in = new CheckedInputStream(this_in, crc); 163 crc.reset(); 164 // Check header magic 165 if (readUShort(in) != GZIP_MAGIC) { 166 throw new ZipException("Not in GZIP format"); 167 } 168 // Check compression method 169 if (readUByte(in) != 8) { 170 throw new ZipException("Unsupported compression method"); 171 } 172 // Read flags 173 int flg = readUByte(in); 174 // Skip MTIME, XFL, and OS fields 175 skipBytes(in, 6); 176 int n = 2 + 2 + 6; 177 // Skip optional extra field 178 if ((flg & FEXTRA) == FEXTRA) { 179 int m = readUShort(in); 180 skipBytes(in, m); 181 n += m + 2; 182 } 183 // Skip optional file name 184 if ((flg & FNAME) == FNAME) { 185 do { 186 n++; 187 } while (readUByte(in) != 0); 188 } 189 // Skip optional file comment 190 if ((flg & FCOMMENT) == FCOMMENT) { 191 do { 192 n++; 193 } while (readUByte(in) != 0); 194 } 195 // Check optional header CRC 196 if ((flg & FHCRC) == FHCRC) { 197 int v = (int)crc.getValue() & 0xffff; 198 if (readUShort(in) != v) { 199 throw new ZipException("Corrupt GZIP header"); 200 } 201 n += 2; 202 } 203 crc.reset(); 204 return n; 205 } 206 207 /* 208 * Reads GZIP member trailer and returns true if the eos 209 * reached, false if there are more (concatenated gzip 210 * data set) 211 */ readTrailer()212 private boolean readTrailer() throws IOException { 213 InputStream in = this.in; 214 int n = inf.getRemaining(); 215 if (n > 0) { 216 in = new SequenceInputStream( 217 new ByteArrayInputStream(buf, len - n, n), 218 new FilterInputStream(in) { 219 public void close() throws IOException {} 220 }); 221 } 222 // Uses left-to-right evaluation order 223 if ((readUInt(in) != crc.getValue()) || 224 // rfc1952; ISIZE is the input size modulo 2^32 225 (readUInt(in) != (inf.getBytesWritten() & 0xffffffffL))) 226 throw new ZipException("Corrupt GZIP trailer"); 227 228 // If there are more bytes available in "in" or 229 // the leftover in the "inf" is > 26 bytes: 230 // this.trailer(8) + next.header.min(10) + next.trailer(8) 231 // try concatenated case 232 if (this.in.available() > 0 || n > 26) { 233 int m = 8; // this.trailer 234 try { 235 m += readHeader(in); // next.header 236 } catch (IOException ze) { 237 return true; // ignore any malformed, do nothing 238 } 239 inf.reset(); 240 if (n > m) 241 inf.setInput(buf, len - n + m, n - m); 242 return false; 243 } 244 return true; 245 } 246 247 /* 248 * Reads unsigned integer in Intel byte order. 249 */ readUInt(InputStream in)250 private long readUInt(InputStream in) throws IOException { 251 long s = readUShort(in); 252 return ((long)readUShort(in) << 16) | s; 253 } 254 255 /* 256 * Reads unsigned short in Intel byte order. 257 */ readUShort(InputStream in)258 private int readUShort(InputStream in) throws IOException { 259 int b = readUByte(in); 260 return (readUByte(in) << 8) | b; 261 } 262 263 /* 264 * Reads unsigned byte. 265 */ readUByte(InputStream in)266 private int readUByte(InputStream in) throws IOException { 267 int b = in.read(); 268 if (b == -1) { 269 throw new EOFException(); 270 } 271 if (b < -1 || b > 255) { 272 // Report on this.in, not argument in; see read{Header, Trailer}. 273 throw new IOException(this.in.getClass().getName() 274 + ".read() returned value out of range -1..255: " + b); 275 } 276 return b; 277 } 278 279 private byte[] tmpbuf = new byte[128]; 280 281 /* 282 * Skips bytes of input data blocking until all bytes are skipped. 283 * Does not assume that the input stream is capable of seeking. 284 */ skipBytes(InputStream in, int n)285 private void skipBytes(InputStream in, int n) throws IOException { 286 while (n > 0) { 287 int len = in.read(tmpbuf, 0, n < tmpbuf.length ? n : tmpbuf.length); 288 if (len == -1) { 289 throw new EOFException(); 290 } 291 n -= len; 292 } 293 } 294 } 295