path: root/mcs/class/Compat.ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib/Zip/Compression/Streams/DeflaterOutputStream.cs

// 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
	}
}