mirror of git://gcc.gnu.org/git/gcc.git
356 lines
10 KiB
Java
356 lines
10 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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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.EOFException;
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import java.io.IOException;
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import java.io.InputStream;
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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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/**
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* The mask for bit 0 of the flag byte.
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*/
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static final int FTEXT = 0x1;
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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 FHCRC = 0x2;
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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 FEXTRA = 0x4;
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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 FNAME = 0x8;
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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 FCOMMENT = 0x10;
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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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* Indicates whether or not the GZIP header has been read in.
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*/
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private boolean readGZIPHeader;
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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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crc = new CRC32();
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readHeader();
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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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/**
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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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// We first have to slurp in the GZIP header, then we feed all the
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// rest of the data to the superclass.
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//
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// As we do that we continually update the CRC32. Once the data is
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// finished, we check the CRC32.
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//
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// This means we don't need our own buffer, as everything is done
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// in the superclass.
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if (!readGZIPHeader)
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readHeader();
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if (eos)
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return -1;
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// System.err.println("GZIPIS.read(byte[], off, len ... " + offset + " and len " + len);
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/* We don't have to read the header,
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* so we just grab data from the superclass.
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*/
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int numRead = super.read(buf, offset, len);
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if (numRead > 0)
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crc.update(buf, offset, numRead);
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if (inf.finished())
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readFooter();
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return numRead;
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}
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/**
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* Reads in the GZIP header.
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*/
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private void readHeader() throws IOException
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{
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/* 1. Check the two magic bytes */
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CRC32 headCRC = new CRC32();
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int magic = in.read();
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if (magic < 0)
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{
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eos = true;
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return;
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}
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int magic2 = in.read();
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if ((magic + (magic2 << 8)) != GZIP_MAGIC)
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throw new IOException("Error in GZIP header, bad magic code");
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headCRC.update(magic);
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headCRC.update(magic2);
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/* 2. Check the compression type (must be 8) */
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int CM = in.read();
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if (CM != Deflater.DEFLATED)
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throw new IOException("Error in GZIP header, data not in deflate format");
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headCRC.update(CM);
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/* 3. Check the flags */
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int flags = in.read();
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if (flags < 0)
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throw new EOFException("Early EOF in GZIP header");
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headCRC.update(flags);
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/* This flag byte is divided into individual bits as follows:
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bit 0 FTEXT
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bit 1 FHCRC
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bit 2 FEXTRA
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bit 3 FNAME
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bit 4 FCOMMENT
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bit 5 reserved
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bit 6 reserved
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bit 7 reserved
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*/
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/* 3.1 Check the reserved bits are zero */
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if ((flags & 0xd0) != 0)
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throw new IOException("Reserved flag bits in GZIP header != 0");
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/* 4.-6. Skip the modification time, extra flags, and OS type */
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for (int i=0; i< 6; i++)
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{
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int readByte = in.read();
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if (readByte < 0)
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throw new EOFException("Early EOF in GZIP header");
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headCRC.update(readByte);
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}
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/* 7. Read extra field */
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if ((flags & FEXTRA) != 0)
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{
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/* Skip subfield id */
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for (int i=0; i< 2; i++)
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{
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int readByte = in.read();
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if (readByte < 0)
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throw new EOFException("Early EOF in GZIP header");
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headCRC.update(readByte);
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}
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if (in.read() < 0 || in.read() < 0)
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throw new EOFException("Early EOF in GZIP header");
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int len1, len2, extraLen;
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len1 = in.read();
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len2 = in.read();
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if ((len1 < 0) || (len2 < 0))
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throw new EOFException("Early EOF in GZIP header");
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headCRC.update(len1);
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headCRC.update(len2);
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extraLen = (len1 << 8) | len2;
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for (int i = 0; i < extraLen;i++)
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{
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int readByte = in.read();
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if (readByte < 0)
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throw new EOFException("Early EOF in GZIP header");
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headCRC.update(readByte);
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}
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}
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/* 8. Read file name */
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if ((flags & FNAME) != 0)
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{
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int readByte;
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while ( (readByte = in.read()) > 0)
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headCRC.update(readByte);
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if (readByte < 0)
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throw new EOFException("Early EOF in GZIP file name");
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headCRC.update(readByte);
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}
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/* 9. Read comment */
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if ((flags & FCOMMENT) != 0)
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{
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int readByte;
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while ( (readByte = in.read()) > 0)
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headCRC.update(readByte);
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if (readByte < 0)
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throw new EOFException("Early EOF in GZIP comment");
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headCRC.update(readByte);
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}
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/* 10. Read header CRC */
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if ((flags & FHCRC) != 0)
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{
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int tempByte;
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int crcval = in.read();
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if (crcval < 0)
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throw new EOFException("Early EOF in GZIP header");
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tempByte = in.read();
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if (tempByte < 0)
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throw new EOFException("Early EOF in GZIP header");
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crcval = (crcval << 8) | tempByte;
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if (crcval != ((int) headCRC.getValue() & 0xffff))
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throw new IOException("Header CRC value mismatch");
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}
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readGZIPHeader = true;
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//System.err.println("Read GZIP header");
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}
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private void readFooter() throws IOException
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{
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byte[] footer = new byte[8];
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int avail = inf.getRemaining();
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if (avail > 8)
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avail = 8;
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System.arraycopy(buf, len - inf.getRemaining(), footer, 0, avail);
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int needed = 8 - avail;
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while (needed > 0)
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{
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int count = in.read(footer, 8-needed, needed);
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if (count <= 0)
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throw new EOFException("Early EOF in GZIP footer");
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needed -= count; //Jewel Jan 16
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}
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int crcval = (footer[0] & 0xff) | ((footer[1] & 0xff) << 8)
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| ((footer[2] & 0xff) << 16) | (footer[3] << 24);
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if (crcval != (int) crc.getValue())
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throw new IOException("GZIP crc sum mismatch, theirs \""
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+ Integer.toHexString(crcval)
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+ "\" and ours \""
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+ Integer.toHexString( (int) crc.getValue()));
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int total = (footer[4] & 0xff) | ((footer[5] & 0xff) << 8)
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| ((footer[6] & 0xff) << 16) | (footer[7] << 24);
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if (total != inf.getTotalOut())
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throw new IOException("Number of bytes mismatch");
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/* FIXME" XXX Should we support multiple members.
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* Difficult, since there may be some bytes still in buf
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*/
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eos = true;
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}
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}
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