deflateroutputstream.cs

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		/// </returns>
		protected byte EncryptByte()
		{
			uint temp = ((keys[2] & 0xFFFF) | 2);
			return (byte)((temp * (temp ^ 1)) >> 8);
		}

		/// <summary>
		/// Update encryption keys 
		/// </summary>		
		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));
		}
#endif

		#endregion
		
		#region Deflation Support
		/// <summary>
		/// Deflates everything in the input buffers.  This will call
		/// <code>def.deflate()</code> until all bytes from the input buffers
		/// are processed.
		/// </summary>
		protected void Deflate()
		{
			while (!deflater_.IsNeedingInput) 
			{
				int deflateCount = deflater_.Deflate(buffer_, 0, buffer_.Length);
				
				if (deflateCount <= 0) 
				{
					break;
				}
#if NETCF_1_0
				if (keys != null) 
#else
				if (cryptoTransform_ != null) 
#endif
				{
					EncryptBlock(buffer_, 0, deflateCount);
				}
				
				baseOutputStream_.Write(buffer_, 0, deflateCount);
			}
			
			if (!deflater_.IsNeedingInput) 
			{
				throw new SharpZipBaseException("DeflaterOutputStream can't deflate all input?");
			}
		}
		#endregion
		
		#region Stream Overrides
		/// <summary>
		/// Gets value indicating stream can be read from
		/// </summary>
		public override bool CanRead 
		{
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Gets a value indicating if seeking is supported for this stream
		/// This property always returns false
		/// </summary>
		public override bool CanSeek {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Get value indicating if this stream supports writing
		/// </summary>
		public override bool CanWrite {
			get {
				return baseOutputStream_.CanWrite;
			}
		}
		
		/// <summary>
		/// Get current length of stream
		/// </summary>
		public override long Length {
			get {
				return baseOutputStream_.Length;
			}
		}
		
		/// <summary>
		/// Gets the current position within the stream.
		/// </summary>
		/// <exception cref="NotSupportedException">Any attempt to set position</exception>
		public override long Position {
			get {
				return baseOutputStream_.Position;
			}
			set {
				throw new NotSupportedException("Position property not supported");
			}
		}
		
		/// <summary>
		/// Sets the current position of this stream to the given value. Not supported by this class!
		/// </summary>
		/// <param name="offset">The offset relative to the <paramref name="origin"/> to seek.</param>
		/// <param name="origin">The <see cref="SeekOrigin"/> to seek from.</param>
		/// <returns>The new position in the stream.</returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException("DeflaterOutputStream Seek not supported");
		}
		
		/// <summary>
		/// Sets the length of this stream to the given value. Not supported by this class!
		/// </summary>
		/// <param name="value">The new stream length.</param>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void SetLength(long value)
		{
			throw new NotSupportedException("DeflaterOutputStream SetLength not supported");
		}
		
		/// <summary>
		/// Read a byte from stream advancing position by one
		/// </summary>
		/// <returns>The byte read cast to an int.  THe value is -1 if at the end of the stream.</returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override int ReadByte()
		{
			throw new NotSupportedException("DeflaterOutputStream ReadByte not supported");
		}
		
		/// <summary>
		/// Read a block of bytes from stream
		/// </summary>
		/// <param name="buffer">The buffer to store read data in.</param>
		/// <param name="offset">The offset to start storing at.</param>
		/// <param name="count">The maximum number of bytes to read.</param>
		/// <returns>The actual number of bytes read.  Zero if end of stream is detected.</returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override int Read(byte[] buffer, int offset, int count)
		{
			throw new NotSupportedException("DeflaterOutputStream Read not supported");
		}
		
		/// <summary>
		/// Asynchronous reads are not supported a NotSupportedException is always thrown
		/// </summary>
		/// <param name="buffer">The buffer to read into.</param>
		/// <param name="offset">The offset to start storing data at.</param>
		/// <param name="count">The number of bytes to read</param>
		/// <param name="callback">The async callback to use.</param>
		/// <param name="state">The state to use.</param>
		/// <returns>Returns an <see cref="IAsyncResult"/></returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override IAsyncResult BeginRead(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
		{
			throw new NotSupportedException("DeflaterOutputStream BeginRead not currently supported");
		}
		
		/// <summary>
		/// Asynchronous writes arent supported, a NotSupportedException is always thrown
		/// </summary>
		/// <param name="buffer">The buffer to write.</param>
		/// <param name="offset">The offset to begin writing at.</param>
		/// <param name="count">The number of bytes to write.</param>
		/// <param name="callback">The <see cref="AsyncCallback"/> to use.</param>
		/// <param name="state">The state object.</param>
		/// <returns>Returns an IAsyncResult.</returns>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
		{
			throw new NotSupportedException("BeginWrite is not supported");
		}
		
		/// <summary>
		/// Flushes the stream by calling <see cref="DeflaterOutputStream.Flush">Flush</see> on the deflater and then
		/// on the underlying stream.  This ensures that all bytes are flushed.
		/// </summary>
		public override void Flush()
		{
			deflater_.Flush();
			Deflate();
			baseOutputStream_.Flush();
		}
		
		/// <summary>
		/// Calls <see cref="Finish"/> and closes the underlying
		/// stream when <see cref="IsStreamOwner"></see> is true.
		/// </summary>
		public override void Close()
		{
			if ( !isClosed_ ) {
				isClosed_ = true;

				try
				{
					Finish();
#if NETCF_1_0
					keys=null;
#else
					if ( cryptoTransform_ != null ) {
						cryptoTransform_.Dispose();
						cryptoTransform_ = null;
					}
#endif
				}
				finally
				{
					if( isStreamOwner_ )
					{
						baseOutputStream_.Close();
					}
				}
			}
		}
		
		/// <summary>
		/// Writes a single byte to the compressed output stream.
		/// </summary>
		/// <param name="value">
		/// The byte value.
		/// </param>
		public override void WriteByte(byte value)
		{
			byte[] b = new byte[1];
			b[0] = value;
			Write(b, 0, 1);
		}
		
		/// <summary>
		/// Writes bytes from an array to the compressed stream.
		/// </summary>
		/// <param name="buffer">
		/// The byte array
		/// </param>
		/// <param name="offset">
		/// The offset into the byte array where to start.
		/// </param>
		/// <param name="count">
		/// The number of bytes to write.
		/// </param>
		public override void Write(byte[] buffer, int offset, int count)
		{
			deflater_.SetInput(buffer, offset, count);
			Deflate();
		}		
		#endregion
		
		#region Instance Fields
		/// <summary>
		/// This buffer is used temporarily to retrieve the bytes from the
		/// deflater and write them to the underlying output stream.
		/// </summary>
		byte[] buffer_;
		
		/// <summary>
		/// The deflater which is used to deflate the stream.
		/// </summary>
		protected Deflater deflater_;
		
		/// <summary>
		/// Base stream the deflater depends on.
		/// </summary>
		protected Stream baseOutputStream_;

		bool isClosed_;
		
		bool isStreamOwner_ = true;
		#endregion
	}
}