reactos/irc/TechBot/Compression/Streams/DeflaterOutputStream.cs

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// DeflaterOutputStream.cs
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module. An independent module is a module which is not derived from
// or based on this library. If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
using System;
using System.IO;
using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip.Compression;
namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
{
/// <summary>
/// This is a special FilterOutputStream deflating the bytes that are
/// written through it. It uses the Deflater for deflating.
///
/// authors of the original java version : Tom Tromey, Jochen Hoenicke
/// </summary>
public class DeflaterOutputStream : Stream
{
/// <summary>
/// This buffer is used temporarily to retrieve the bytes from the
/// deflater and write them to the underlying output stream.
/// </summary>
protected byte[] buf;
/// <summary>
/// The deflater which is used to deflate the stream.
/// </summary>
protected Deflater def;
/// <summary>
/// base stream the deflater depends on.
/// </summary>
protected Stream baseOutputStream;
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanRead {
get {
return baseOutputStream.CanRead;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanSeek {
get {
return false;
// return baseOutputStream.CanSeek;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanWrite {
get {
return baseOutputStream.CanWrite;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Length {
get {
return baseOutputStream.Length;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Position {
get {
return baseOutputStream.Position;
}
set {
baseOutputStream.Position = value;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException("Seek not supported"); // -jr- 01-Dec-2003
// return baseOutputStream.Seek(offset, origin);
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override void SetLength(long val)
{
baseOutputStream.SetLength(val);
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override int ReadByte()
{
return baseOutputStream.ReadByte();
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override int Read(byte[] b, int off, int len)
{
return baseOutputStream.Read(b, off, len);
}
// -jr- 01-Dec-2003
public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
throw new NotSupportedException("Asynch read not currently supported");
}
// -jr- 01-Dec-2003
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
throw new NotSupportedException("Asynch write not currently supported");
}
/// <summary>
/// Deflates everything in the def's input buffers. This will call
/// <code>def.deflate()</code> until all bytes from the input buffers
/// are processed.
/// </summary>
protected void Deflate()
{
while (!def.IsNeedingInput) {
int len = def.Deflate(buf, 0, buf.Length);
// System.err.println("DOS deflated " + len + " baseOutputStream of " + buf.length);
if (len <= 0) {
break;
}
baseOutputStream.Write(buf, 0, len);
}
if (!def.IsNeedingInput) {
throw new ApplicationException("Can't deflate all input?");
}
}
/// <summary>
/// Creates a new DeflaterOutputStream with a default Deflater and default buffer size.
/// </summary>
/// <param name="baseOutputStream">
/// the output stream where deflated output should be written.
/// </param>
public DeflaterOutputStream(Stream baseOutputStream) : this(baseOutputStream, new Deflater(), 512)
{
}
/// <summary>
/// Creates a new DeflaterOutputStream with the given Deflater and
/// default buffer size.
/// </summary>
/// <param name="baseOutputStream">
/// the output stream where deflated output should be written.
/// </param>
/// <param name="defl">
/// the underlying deflater.
/// </param>
public DeflaterOutputStream(Stream baseOutputStream, Deflater defl) :this(baseOutputStream, defl, 512)
{
}
/// <summary>
/// Creates a new DeflaterOutputStream with the given Deflater and
/// buffer size.
/// </summary>
/// <param name="baseOutputStream">
/// the output stream where deflated output should be written.
/// </param>
/// <param name="defl">
/// the underlying deflater.
/// </param>
/// <param name="bufsize">
/// the buffer size.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if bufsize isn't positive.
/// </exception>
public DeflaterOutputStream(Stream baseOutputStream, Deflater defl, int bufsize)
{
this.baseOutputStream = baseOutputStream;
if (bufsize <= 0) {
throw new InvalidOperationException("bufsize <= 0");
}
buf = new byte[bufsize];
def = defl;
}
/// <summary>
/// Flushes the stream by calling flush() on the deflater and then
/// on the underlying stream. This ensures that all bytes are
/// flushed.
/// </summary>
public override void Flush()
{
def.Flush();
Deflate();
baseOutputStream.Flush();
}
/// <summary>
/// Finishes the stream by calling finish() on the deflater.
/// </summary>
public virtual void Finish()
{
def.Finish();
while (!def.IsFinished) {
int len = def.Deflate(buf, 0, buf.Length);
if (len <= 0) {
break;
}
// kidnthrain encryption alteration
if (this.Password != null) {
// plain data has been deflated. Now encrypt result
this.EncryptBlock(buf, 0, len);
}
baseOutputStream.Write(buf, 0, len);
}
if (!def.IsFinished) {
throw new ApplicationException("Can't deflate all input?");
}
baseOutputStream.Flush();
}
/// <summary>
/// Calls finish () and closes the stream.
/// </summary>
public override void Close()
{
Finish();
baseOutputStream.Close();
}
/// <summary>
/// Writes a single byte to the compressed output stream.
/// </summary>
/// <param name="bval">
/// the byte value.
/// </param>
public override void WriteByte(byte bval)
{
byte[] b = new byte[1];
b[0] = (byte) bval;
Write(b, 0, 1);
}
/// <summary>
/// Writes a len bytes from an array to the compressed stream.
/// </summary>
/// <param name="buf">
/// the byte array.
/// </param>
/// <param name="off">
/// the offset into the byte array where to start.
/// </param>
/// <param name="len">
/// the number of bytes to write.
/// </param>
public override void Write(byte[] buf, int off, int len)
{
// System.err.println("DOS with off " + off + " and len " + len);
def.SetInput(buf, off, len);
Deflate();
}
#region Encryption
string password = null;
uint[] keys = null;
public string Password {
get {
return password;
}
set {
password = value;
}
}
//The beauty of xor-ing bits is that
//plain ^ key = enc
//and enc ^ key = plain
//accordingly, this is the exact same as the decrypt byte
//function in InflaterInputStream
protected byte EncryptByte()
{
uint temp = ((keys[2] & 0xFFFF) | 2);
return (byte)((temp * (temp ^ 1)) >> 8);
}
/// <summary>
/// Takes a buffer of data and uses the keys
/// that have been previously initialized from a
/// password and then updated via a random encryption header
/// to encrypt that data
/// </summary>
protected void EncryptBlock(byte[] buf, int off, int len)
{
for (int i = off; i < off + len; ++i) {
byte oldbyte = buf[i];
buf[i] ^= EncryptByte();
UpdateKeys(oldbyte);
}
}
/// <summary>
/// Initializes our encryption keys using a given password
/// </summary>
protected void InitializePassword(string password) {
keys = new uint[] {
0x12345678,
0x23456789,
0x34567890
};
for (int i = 0; i < password.Length; ++i) {
UpdateKeys((byte)password[i]);
}
}
protected void UpdateKeys(byte ch)
{
keys[0] = Crc32.ComputeCrc32(keys[0], ch);
keys[1] = keys[1] + (byte)keys[0];
keys[1] = keys[1] * 134775813 + 1;
keys[2] = Crc32.ComputeCrc32(keys[2], (byte)(keys[1] >> 24));
}
#endregion
}
}