ecd16bf665
PR libgcj/14446: * java/util/zip/GZIPInputStream.java (read): Avoid sign extension when comparing CRCs. * java/util/zip/InflaterInputStream.java (onebytebuffer): New field. (read()): New overload. From-SVN: r87882
253 lines
6.8 KiB
Java
253 lines
6.8 KiB
Java
/* GZIPInputStream.java - Input filter for reading gzip file
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Copyright (C) 1999, 2000, 2001, 2002, 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.util.zip;
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import java.io.InputStream;
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import java.io.IOException;
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/**
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* This filter stream is used to decompress a "GZIP" format stream.
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* The "GZIP" format is described in RFC 1952.
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*
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* @author John Leuner
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* @author Tom Tromey
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* @since JDK 1.1
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*/
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public class GZIPInputStream
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extends InflaterInputStream
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{
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/**
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* The magic number found at the start of a GZIP stream.
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*/
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public static final int GZIP_MAGIC = 0x8b1f;
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static final int Z_DEFLATED = 8;
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/**
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* The mask for bit 1 of the flag byte.
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*/
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static final int HEAD_CRC = 0x02;
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/**
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* The mask for bit 2 of the flag byte.
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*/
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static final int EXTRA_FIELD = 0x04;
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/**
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* The mask for bit 3 of the flag byte.
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*/
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static final int ORIG_NAME = 0x08;
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/**
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* The mask for bit 4 of the flag byte.
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*/
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static final int COMMENT = 0x10;
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/**
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* The mask for all reserved bits of the flag byte.
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*/
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static final int RESERVED = 0xe0;
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/**
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* The CRC-32 checksum value for uncompressed data.
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*/
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protected CRC32 crc;
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/**
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* Indicates whether or not the end of the stream has been reached.
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*/
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protected boolean eos;
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/**
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* Creates a GZIPInputStream with the default buffer size.
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*
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* @param in The stream to read compressed data from
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* (in GZIP format).
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*
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* @throws IOException if an error occurs during an I/O operation.
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*/
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public GZIPInputStream(InputStream in)
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throws IOException
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{
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this(in, 4096);
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}
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/**
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* Creates a GZIPInputStream with the specified buffer size.
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*
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* @param in The stream to read compressed data from
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* (in GZIP format).
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* @param size The size of the buffer to use.
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*
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* @throws IOException if an error occurs during an I/O operation.
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* @throws IllegalArgumentException if <code>size</code>
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* is less than or equal to 0.
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*/
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public GZIPInputStream(InputStream in, int size)
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throws IOException
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{
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super(in, new Inflater(true), size);
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// NOTE: header reading code taken from zlib's gzio.c.
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// Read the magic number.
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int magic = eof_read() | (eof_read() << 8);
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if (magic != GZIP_MAGIC)
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throw new ZipException("gzip header corrupted");
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int method = eof_read();
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int flags = eof_read();
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// Test from zlib.
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if (method != Z_DEFLATED || (flags & RESERVED) != 0)
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throw new ZipException("gzip header corrupted");
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// Discard time, xflags, OS code.
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for (int i = 0; i < 6; ++i)
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eof_read();
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// Skip the extra field.
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if ((flags & EXTRA_FIELD) != 0)
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{
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int len = eof_read() | (eof_read() << 8);
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while (len-- != 0)
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eof_read();
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}
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if ((flags & ORIG_NAME) != 0)
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{
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while (true)
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{
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int c = eof_read();
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if (c == 0)
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break;
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}
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}
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if ((flags & COMMENT) != 0)
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{
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while (true)
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{
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int c = eof_read();
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if (c == 0)
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break;
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}
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}
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if ((flags & HEAD_CRC) != 0)
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{
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// FIXME: consider checking CRC of the header.
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eof_read();
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eof_read();
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}
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crc = new CRC32();
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}
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/**
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* Closes the input stream.
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*
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* @throws IOException if an error occurs during an I/O operation.
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*/
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public void close()
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throws IOException
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{
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// Nothing to do here.
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super.close();
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}
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private final int eof_read() throws IOException
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{
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int r = in.read();
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if (r == -1)
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throw new ZipException("gzip header corrupted");
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return r & 0xff;
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}
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/**
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* Reads in GZIP-compressed data and stores it in uncompressed form
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* into an array of bytes. The method will block until either
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* enough input data becomes available or the compressed stream
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* reaches its end.
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*
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* @param buf the buffer into which the uncompressed data will
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* be stored.
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* @param offset the offset indicating where in <code>buf</code>
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* the uncompressed data should be placed.
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* @param len the number of uncompressed bytes to be read.
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*/
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public int read(byte[] buf, int offset, int len) throws IOException
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{
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if (eos)
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return -1;
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int r = super.read(buf, offset, len);
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if (r == -1)
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{
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eos = true;
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byte[] tmp = new byte[8];
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// First copy remaining bytes from inflater input buffer.
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int avail = inf.getRemaining();
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System.arraycopy(this.buf, this.len - avail, tmp, 0, avail);
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// Now read remaining bytes from wrapped input stream.
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for (int i = avail; i < 8; ++i)
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{
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tmp[i] = (byte) eof_read();
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}
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// Be careful to avoid sign extension here; CRC32.getValue()
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// returns a long.
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long header_crc = read4(tmp, 0) & 0xffffffffL;
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if (crc.getValue() != header_crc)
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throw new ZipException("corrupted gzip file - crc mismatch");
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int isize = read4(tmp, 4);
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if (inf.getTotalOut() != isize)
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throw new ZipException("corrupted gzip file - size mismatch");
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return -1;
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}
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crc.update(buf, offset, r);
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return r;
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}
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private final int read4(byte[] buf, int offset) throws IOException
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{
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return (((buf[offset + 3] & 0xFF) << 24) + ((buf[offset + 2] & 0xFF) << 16)
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+ ((buf[offset + 1] & 0xFF) << 8) + (buf[offset] & 0xFF));
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}
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}
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