1 /* 2 * Copyright (c) 1996, 2019, 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 * @since 1.1 42 * 43 */ 44 public 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 * @throws ZipException if a GZIP format error has occurred or the 72 * compression method used is unsupported 73 * @throws IOException if an I/O error has occurred 74 * @throws 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 usesDefaultInflater = true; 79 readHeader(in); 80 } 81 82 /** 83 * Creates a new input stream with a default buffer size. 84 * @param in the input stream 85 * 86 * @throws ZipException if a GZIP format error has occurred or the 87 * compression method used is unsupported 88 * @throws IOException if an I/O error has occurred 89 */ GZIPInputStream(InputStream in)90 public GZIPInputStream(InputStream in) throws IOException { 91 this(in, 512); 92 } 93 94 /** 95 * Reads uncompressed data into an array of bytes. If {@code len} is not 96 * zero, the method will block until some input can be decompressed; otherwise, 97 * no bytes are read and {@code 0} is returned. 98 * @param buf the buffer into which the data is read 99 * @param off the start offset in the destination array {@code b} 100 * @param len the maximum number of bytes read 101 * @return the actual number of bytes read, or -1 if the end of the 102 * compressed input stream is reached 103 * 104 * @throws NullPointerException If {@code buf} is {@code null}. 105 * @throws IndexOutOfBoundsException If {@code off} is negative, 106 * {@code len} is negative, or {@code len} is greater than 107 * {@code buf.length - off} 108 * @throws ZipException if the compressed input data is corrupt. 109 * @throws IOException if an I/O error has occurred. 110 * 111 */ read(byte[] buf, int off, int len)112 public int read(byte[] buf, int off, int len) throws IOException { 113 ensureOpen(); 114 if (eos) { 115 return -1; 116 } 117 int n = super.read(buf, off, len); 118 if (n == -1) { 119 if (readTrailer()) 120 eos = true; 121 else 122 return this.read(buf, off, len); 123 } else { 124 crc.update(buf, off, n); 125 } 126 return n; 127 } 128 129 /** 130 * Closes this input stream and releases any system resources associated 131 * with the stream. 132 * @throws IOException if an I/O error has occurred 133 */ close()134 public void close() throws IOException { 135 if (!closed) { 136 super.close(); 137 eos = true; 138 closed = true; 139 } 140 } 141 142 /** 143 * GZIP header magic number. 144 */ 145 public static final int GZIP_MAGIC = 0x8b1f; 146 147 /* 148 * File header flags. 149 */ 150 private static final int FTEXT = 1; // Extra text 151 private static final int FHCRC = 2; // Header CRC 152 private static final int FEXTRA = 4; // Extra field 153 private static final int FNAME = 8; // File name 154 private static final int FCOMMENT = 16; // File comment 155 156 /* 157 * Reads GZIP member header and returns the total byte number 158 * of this member header. 159 */ readHeader(InputStream this_in)160 private int readHeader(InputStream this_in) throws IOException { 161 CheckedInputStream in = new CheckedInputStream(this_in, crc); 162 crc.reset(); 163 // Check header magic 164 if (readUShort(in) != GZIP_MAGIC) { 165 throw new ZipException("Not in GZIP format"); 166 } 167 // Check compression method 168 if (readUByte(in) != 8) { 169 throw new ZipException("Unsupported compression method"); 170 } 171 // Read flags 172 int flg = readUByte(in); 173 // Skip MTIME, XFL, and OS fields 174 skipBytes(in, 6); 175 int n = 2 + 2 + 6; 176 // Skip optional extra field 177 if ((flg & FEXTRA) == FEXTRA) { 178 int m = readUShort(in); 179 skipBytes(in, m); 180 n += m + 2; 181 } 182 // Skip optional file name 183 if ((flg & FNAME) == FNAME) { 184 do { 185 n++; 186 } while (readUByte(in) != 0); 187 } 188 // Skip optional file comment 189 if ((flg & FCOMMENT) == FCOMMENT) { 190 do { 191 n++; 192 } while (readUByte(in) != 0); 193 } 194 // Check optional header CRC 195 if ((flg & FHCRC) == FHCRC) { 196 int v = (int)crc.getValue() & 0xffff; 197 if (readUShort(in) != v) { 198 throw new ZipException("Corrupt GZIP header"); 199 } 200 n += 2; 201 } 202 crc.reset(); 203 return n; 204 } 205 206 /* 207 * Reads GZIP member trailer and returns true if the eos 208 * reached, false if there are more (concatenated gzip 209 * data set) 210 */ readTrailer()211 private boolean readTrailer() throws IOException { 212 InputStream in = this.in; 213 int n = inf.getRemaining(); 214 if (n > 0) { 215 in = new SequenceInputStream( 216 new ByteArrayInputStream(buf, len - n, n), 217 new FilterInputStream(in) { 218 public void close() throws IOException {} 219 }); 220 } 221 // Uses left-to-right evaluation order 222 if ((readUInt(in) != crc.getValue()) || 223 // rfc1952; ISIZE is the input size modulo 2^32 224 (readUInt(in) != (inf.getBytesWritten() & 0xffffffffL))) 225 throw new ZipException("Corrupt GZIP trailer"); 226 227 // If there are more bytes available in "in" or 228 // the leftover in the "inf" is > 26 bytes: 229 // this.trailer(8) + next.header.min(10) + next.trailer(8) 230 // try concatenated case 231 if (this.in.available() > 0 || n > 26) { 232 int m = 8; // this.trailer 233 try { 234 m += readHeader(in); // next.header 235 } catch (IOException ze) { 236 return true; // ignore any malformed, do nothing 237 } 238 inf.reset(); 239 if (n > m) 240 inf.setInput(buf, len - n + m, n - m); 241 return false; 242 } 243 return true; 244 } 245 246 /* 247 * Reads unsigned integer in Intel byte order. 248 */ readUInt(InputStream in)249 private long readUInt(InputStream in) throws IOException { 250 long s = readUShort(in); 251 return ((long)readUShort(in) << 16) | s; 252 } 253 254 /* 255 * Reads unsigned short in Intel byte order. 256 */ readUShort(InputStream in)257 private int readUShort(InputStream in) throws IOException { 258 int b = readUByte(in); 259 return (readUByte(in) << 8) | b; 260 } 261 262 /* 263 * Reads unsigned byte. 264 */ readUByte(InputStream in)265 private int readUByte(InputStream in) throws IOException { 266 int b = in.read(); 267 if (b == -1) { 268 throw new EOFException(); 269 } 270 if (b < -1 || b > 255) { 271 // Report on this.in, not argument in; see read{Header, Trailer}. 272 throw new IOException(this.in.getClass().getName() 273 + ".read() returned value out of range -1..255: " + b); 274 } 275 return b; 276 } 277 278 private byte[] tmpbuf = new byte[128]; 279 280 /* 281 * Skips bytes of input data blocking until all bytes are skipped. 282 * Does not assume that the input stream is capable of seeking. 283 */ skipBytes(InputStream in, int n)284 private void skipBytes(InputStream in, int n) throws IOException { 285 while (n > 0) { 286 int len = in.read(tmpbuf, 0, n < tmpbuf.length ? n : tmpbuf.length); 287 if (len == -1) { 288 throw new EOFException(); 289 } 290 n -= len; 291 } 292 } 293 } 294