1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233
/* * @(#)GZIPInputStream.java 1.33 06/04/07 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.util.zip; import java.io.SequenceInputStream; import java.io.ByteArrayInputStream; import java.io.InputStream; import java.io.IOException; import java.io.EOFException; /** * This class implements a stream filter for reading compressed data in * the GZIP file format. * * @see InflaterInputStream * @version 1.33, 04/07/06 * @author David Connelly * */ public class GZIPInputStream extends InflaterInputStream { /** * CRC-32 for uncompressed data. */ protected CRC32 crc = new CRC32(); /** * Indicates end of input stream. */ protected boolean eos; private boolean closed = false; /** * Check to make sure that this stream has not been closed */ private void ensureOpen() throws IOException { if (closed) { throw new IOException("Stream closed"); } } /** * Creates a new input stream with the specified buffer size. * @param in the input stream * @param size the input buffer size * @exception IOException if an I/O error has occurred * @exception IllegalArgumentException if size is <= 0 */ public GZIPInputStream(InputStream in, int size) throws IOException { super(in, new Inflater(true), size); usesDefaultInflater = true; readHeader(); crc.reset(); } /** * Creates a new input stream with a default buffer size. * @param in the input stream * @exception IOException if an I/O error has occurred */ public GZIPInputStream(InputStream in) throws IOException { this(in, 512); } /** * Reads uncompressed data into an array of bytes. If <code>len</code> is not * zero, the method will block until some input can be decompressed; otherwise, * no bytes are read and <code>0</code> is returned. * @param buf the buffer into which the data is read * @param off the start offset in the destination array <code>b</code> * @param len the maximum number of bytes read * @return the actual number of bytes read, or -1 if the end of the * compressed input stream is reached * @exception NullPointerException If <code>buf</code> is <code>null</code>. * @exception IndexOutOfBoundsException If <code>off</code> is negative, * <code>len</code> is negative, or <code>len</code> is greater than * <code>buf.length - off</code> * @exception IOException if an I/O error has occurred or the compressed * input data is corrupt */ public int read(byte[] buf, int off, int len) throws IOException { ensureOpen(); if (eos) { return -1; } len = super.read(buf, off, len); if (len == -1) { readTrailer(); eos = true; } else { crc.update(buf, off, len); } return len; } /** * Closes this input stream and releases any system resources associated * with the stream. * @exception IOException if an I/O error has occurred */ public void close() throws IOException { if (!closed) { super.close(); eos = true; closed = true; } } /** * GZIP header magic number. */ public final static int GZIP_MAGIC = 0x8b1f; /* * File header flags. */ private final static int FTEXT = 1; // Extra text private final static int FHCRC = 2; // Header CRC private final static int FEXTRA = 4; // Extra field private final static int FNAME = 8; // File name private final static int FCOMMENT = 16; // File comment /* * Reads GZIP member header. */ private void readHeader() throws IOException { CheckedInputStream in = new CheckedInputStream(this.in, crc); crc.reset(); // Check header magic if (readUShort(in) != GZIP_MAGIC) { throw new IOException("Not in GZIP format"); } // Check compression method if (readUByte(in) != 8) { throw new IOException("Unsupported compression method"); } // Read flags int flg = readUByte(in); // Skip MTIME, XFL, and OS fields skipBytes(in, 6); // Skip optional extra field if ((flg & FEXTRA) == FEXTRA) { skipBytes(in, readUShort(in)); } // Skip optional file name if ((flg & FNAME) == FNAME) { while (readUByte(in) != 0) ; } // Skip optional file comment if ((flg & FCOMMENT) == FCOMMENT) { while (readUByte(in) != 0) ; } // Check optional header CRC if ((flg & FHCRC) == FHCRC) { int v = (int)crc.getValue() & 0xffff; if (readUShort(in) != v) { throw new IOException("Corrupt GZIP header"); } } } /* * Reads GZIP member trailer. */ private void readTrailer() throws IOException { InputStream in = this.in; int n = inf.getRemaining(); if (n > 0) { in = new SequenceInputStream( new ByteArrayInputStream(buf, len - n, n), in); } // Uses left-to-right evaluation order if ((readUInt(in) != crc.getValue()) || // rfc1952; ISIZE is the input size modulo 2^32 (readUInt(in) != (inf.getBytesWritten() & 0xffffffffL))) throw new IOException("Corrupt GZIP trailer"); } /* * Reads unsigned integer in Intel byte order. */ private long readUInt(InputStream in) throws IOException { long s = readUShort(in); return ((long)readUShort(in) << 16) | s; } /* * Reads unsigned short in Intel byte order. */ private int readUShort(InputStream in) throws IOException { int b = readUByte(in); return ((int)readUByte(in) << 8) | b; } /* * Reads unsigned byte. */ private int readUByte(InputStream in) throws IOException { int b = in.read(); if (b == -1) { throw new EOFException(); } if (b < -1 || b > 255) { // Report on this.in, not argument in; see read{Header, Trailer}. throw new IOException(this.in.getClass().getName() + ".read() returned value out of range -1..255: " + b); } return b; } private byte[] tmpbuf = new byte[128]; /* * Skips bytes of input data blocking until all bytes are skipped. * Does not assume that the input stream is capable of seeking. */ private void skipBytes(InputStream in, int n) throws IOException { while (n > 0) { int len = in.read(tmpbuf, 0, n < tmpbuf.length ? n : tmpbuf.length); if (len == -1) { throw new EOFException(); } n -= len; } } }