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387 lines
10 KiB
C#
387 lines
10 KiB
C#
// InflaterInputStream.cs
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// Copyright (C) 2001 Mike Krueger
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//
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// This file was translated from java, it was part of the GNU Classpath
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// Copyright (C) 2001 Free Software Foundation, Inc.
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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//
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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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//
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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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using System;
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using System.IO;
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using ICSharpCode.SharpZipLib.Zip.Compression;
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using ICSharpCode.SharpZipLib.Checksums;
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namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
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{
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/// <summary>
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/// This filter stream is used to decompress data compressed baseInputStream the "deflate"
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/// format. The "deflate" format is described baseInputStream RFC 1951.
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///
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/// This stream may form the basis for other decompression filters, such
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/// as the <code>GzipInputStream</code>.
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///
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/// author of the original java version : John Leuner
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/// </summary>
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public class InflaterInputStream : Stream
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{
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//Variables
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/// <summary>
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/// Decompressor for this filter
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/// </summary>
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protected Inflater inf;
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/// <summary>
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/// Byte array used as a buffer
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/// </summary>
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protected byte[] buf;
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/// <summary>
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/// Size of buffer
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/// </summary>
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protected int len;
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//We just use this if we are decoding one byte at a time with the read() call
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private byte[] onebytebuffer = new byte[1];
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/// <summary>
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/// base stream the inflater depends on.
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/// </summary>
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protected Stream baseInputStream;
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protected long csize;
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override bool CanRead {
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get {
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return baseInputStream.CanRead;
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}
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override bool CanSeek {
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get {
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return false;
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// return baseInputStream.CanSeek;
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}
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override bool CanWrite {
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get {
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return baseInputStream.CanWrite;
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}
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override long Length {
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get {
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return len;
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}
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override long Position {
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get {
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return baseInputStream.Position;
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}
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set {
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baseInputStream.Position = value;
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}
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}
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/// <summary>
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/// Flushes the baseInputStream
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/// </summary>
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public override void Flush()
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{
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baseInputStream.Flush();
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override long Seek(long offset, SeekOrigin origin)
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{
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throw new NotSupportedException("Seek not supported"); // -jr- 01-Dec-2003
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override void SetLength(long val)
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{
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baseInputStream.SetLength(val);
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override void Write(byte[] array, int offset, int count)
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{
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baseInputStream.Write(array, offset, count);
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}
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/// <summary>
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/// I needed to implement the abstract member.
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/// </summary>
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public override void WriteByte(byte val)
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{
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baseInputStream.WriteByte(val);
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}
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// -jr- 01-Dec-2003 This may be flawed for some base streams? Depends on implementation of BeginWrite
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public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
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{
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throw new NotSupportedException("Asynch write not currently supported");
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}
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//Constructors
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/// <summary>
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/// Create an InflaterInputStream with the default decompresseor
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/// and a default buffer size.
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/// </summary>
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/// <param name = "baseInputStream">
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/// the InputStream to read bytes from
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/// </param>
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public InflaterInputStream(Stream baseInputStream) : this(baseInputStream, new Inflater(), 4096)
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{
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}
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/// <summary>
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/// Create an InflaterInputStream with the specified decompresseor
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/// and a default buffer size.
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/// </summary>
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/// <param name = "baseInputStream">
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/// the InputStream to read bytes from
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/// </param>
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/// <param name = "inf">
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/// the decompressor used to decompress data read from baseInputStream
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/// </param>
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public InflaterInputStream(Stream baseInputStream, Inflater inf) : this(baseInputStream, inf, 4096)
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{
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}
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/// <summary>
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/// Create an InflaterInputStream with the specified decompresseor
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/// and a specified buffer size.
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/// </summary>
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/// <param name = "baseInputStream">
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/// the InputStream to read bytes from
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/// </param>
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/// <param name = "inf">
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/// the decompressor used to decompress data read from baseInputStream
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/// </param>
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/// <param name = "size">
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/// size of the buffer to use
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/// </param>
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public InflaterInputStream(Stream baseInputStream, Inflater inf, int size)
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{
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this.baseInputStream = baseInputStream;
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this.inf = inf;
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try {
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this.len = (int)baseInputStream.Length;
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} catch (Exception) {
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// the stream may not support .Length
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this.len = 0;
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}
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if (size <= 0) {
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throw new ArgumentOutOfRangeException("size <= 0");
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}
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buf = new byte[size]; //Create the buffer
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}
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//Methods
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/// <summary>
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/// Returns 0 once the end of the stream (EOF) has been reached.
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/// Otherwise returns 1.
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/// </summary>
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public virtual int Available {
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get {
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return inf.IsFinished ? 0 : 1;
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}
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}
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/// <summary>
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/// Closes the input stream
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/// </summary>
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public override void Close()
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{
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baseInputStream.Close();
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}
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/// <summary>
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/// Fills the buffer with more data to decompress.
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/// </summary>
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protected void Fill()
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{
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len = baseInputStream.Read(buf, 0, buf.Length);
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// decrypting crypted data
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if (cryptbuffer != null) {
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DecryptBlock(buf, 0, System.Math.Min((int)(csize - inf.TotalIn), buf.Length));
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}
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if (len <= 0) {
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throw new ApplicationException("Deflated stream ends early.");
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}
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inf.SetInput(buf, 0, len);
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}
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/// <summary>
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/// Reads one byte of decompressed data.
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///
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/// The byte is baseInputStream the lower 8 bits of the int.
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/// </summary>
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public override int ReadByte()
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{
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int nread = Read(onebytebuffer, 0, 1); //read one byte
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if (nread > 0) {
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return onebytebuffer[0] & 0xff;
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}
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return -1; // ok
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}
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/// <summary>
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/// Decompresses data into the byte array
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/// </summary>
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/// <param name ="b">
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/// the array to read and decompress data into
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/// </param>
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/// <param name ="off">
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/// the offset indicating where the data should be placed
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/// </param>
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/// <param name ="len">
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/// the number of bytes to decompress
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/// </param>
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public override int Read(byte[] b, int off, int len)
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{
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for (;;) {
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int count;
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try {
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count = inf.Inflate(b, off, len);
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} catch (Exception e) {
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throw new ZipException(e.ToString());
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}
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if (count > 0) {
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return count;
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}
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if (inf.IsNeedingDictionary) {
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throw new ZipException("Need a dictionary");
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} else if (inf.IsFinished) {
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return 0;
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} else if (inf.IsNeedingInput) {
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Fill();
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} else {
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throw new InvalidOperationException("Don't know what to do");
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}
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}
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}
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/// <summary>
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/// Skip specified number of bytes of uncompressed data
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/// </summary>
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/// <param name ="n">
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/// number of bytes to skip
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/// </param>
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public long Skip(long n)
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{
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if (n < 0) {
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throw new ArgumentOutOfRangeException("n");
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}
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int len = 2048;
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if (n < len) {
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len = (int) n;
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}
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byte[] tmp = new byte[len];
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return (long)baseInputStream.Read(tmp, 0, tmp.Length);
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}
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#region Encryption stuff
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protected byte[] cryptbuffer = null;
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uint[] keys = null;
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protected byte DecryptByte()
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{
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uint temp = ((keys[2] & 0xFFFF) | 2);
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return (byte)((temp * (temp ^ 1)) >> 8);
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}
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protected void DecryptBlock(byte[] buf, int off, int len)
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{
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for (int i = off; i < off + len; ++i) {
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buf[i] ^= DecryptByte();
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UpdateKeys(buf[i]);
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}
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}
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protected void InitializePassword(string password)
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{
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keys = new uint[] {
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0x12345678,
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0x23456789,
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0x34567890
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};
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for (int i = 0; i < password.Length; ++i) {
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UpdateKeys((byte)password[i]);
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}
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}
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protected void UpdateKeys(byte ch)
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{
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keys[0] = Crc32.ComputeCrc32(keys[0], ch);
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keys[1] = keys[1] + (byte)keys[0];
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keys[1] = keys[1] * 134775813 + 1;
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keys[2] = Crc32.ComputeCrc32(keys[2], (byte)(keys[1] >> 24));
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}
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#endregion
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}
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}
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