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diff --git a/zlib/contrib/dotzlib/DotZLib/GZipStream.cs b/zlib/contrib/dotzlib/DotZLib/GZipStream.cs
new file mode 100644
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+++ b/zlib/contrib/dotzlib/DotZLib/GZipStream.cs
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+//
+// © Copyright Henrik Ravn 2004
+//
+// Use, modification and distribution are subject to the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+using System;
+using System.IO;
+using System.Runtime.InteropServices;
+
+namespace DotZLib
+{
+	/// <summary>
+	/// Implements a compressed <see cref="Stream"/>, in GZip (.gz) format.
+	/// </summary>
+	public class GZipStream : Stream, IDisposable
+	{
+        #region Dll Imports
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
+        private static extern IntPtr gzopen(string name, string mode);
+
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
+        private static extern int gzclose(IntPtr gzFile);
+
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
+        private static extern int gzwrite(IntPtr gzFile, int data, int length);
+
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
+        private static extern int gzread(IntPtr gzFile, int data, int length);
+
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
+        private static extern int gzgetc(IntPtr gzFile);
+
+        [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
+        private static extern int gzputc(IntPtr gzFile, int c);
+
+        #endregion
+
+        #region Private data
+        private IntPtr _gzFile;
+        private bool _isDisposed = false;
+        private bool _isWriting;
+        #endregion
+
+        #region Constructors
+        /// <summary>
+        /// Creates a new file as a writeable GZipStream
+        /// </summary>
+        /// <param name="fileName">The name of the compressed file to create</param>
+        /// <param name="level">The compression level to use when adding data</param>
+        /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
+		public GZipStream(string fileName, CompressLevel level)
+		{
+            _isWriting = true;
+            _gzFile = gzopen(fileName, String.Format("wb{0}", (int)level));
+            if (_gzFile == IntPtr.Zero)
+                throw new ZLibException(-1, "Could not open " + fileName);
+		}
+
+        /// <summary>
+        /// Opens an existing file as a readable GZipStream
+        /// </summary>
+        /// <param name="fileName">The name of the file to open</param>
+        /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
+        public GZipStream(string fileName)
+        {
+            _isWriting = false;
+            _gzFile = gzopen(fileName, "rb");
+            if (_gzFile == IntPtr.Zero)
+                throw new ZLibException(-1, "Could not open " + fileName);
+
+        }
+        #endregion
+
+        #region Access properties
+        /// <summary>
+        /// Returns true of this stream can be read from, false otherwise
+        /// </summary>
+        public override bool CanRead
+        {
+            get
+            {
+                return !_isWriting;
+            }
+        }
+
+
+        /// <summary>
+        /// Returns false.
+        /// </summary>
+        public override bool CanSeek
+        {
+            get
+            {
+                return false;
+            }
+        }
+
+        /// <summary>
+        /// Returns true if this tsream is writeable, false otherwise
+        /// </summary>
+        public override bool CanWrite
+        {
+            get
+            {
+                return _isWriting;
+            }
+        }
+        #endregion
+
+        #region Destructor & IDispose stuff
+
+        /// <summary>
+        /// Destroys this instance
+        /// </summary>
+        ~GZipStream()
+        {
+            cleanUp(false);
+        }
+
+        /// <summary>
+        /// Closes the external file handle
+        /// </summary>
+        public void Dispose()
+        {
+            cleanUp(true);
+        }
+
+        // Does the actual closing of the file handle.
+        private void cleanUp(bool isDisposing)
+        {
+            if (!_isDisposed)
+            {
+                gzclose(_gzFile);
+                _isDisposed = true;
+            }
+        }
+        #endregion
+
+        #region Basic reading and writing
+        /// <summary>
+        /// Attempts to read a number of bytes from the stream.
+        /// </summary>
+        /// <param name="buffer">The destination data buffer</param>
+        /// <param name="offset">The index of the first destination byte in <c>buffer</c></param>
+        /// <param name="count">The number of bytes requested</param>
+        /// <returns>The number of bytes read</returns>
+        /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
+        /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
+        /// <exception cref="ArgumentException">If <c>offset</c>  + <c>count</c> is &gt; buffer.Length</exception>
+        /// <exception cref="NotSupportedException">If this stream is not readable.</exception>
+        /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
+        public override int Read(byte[] buffer, int offset, int count)
+        {
+            if (!CanRead) throw new NotSupportedException();
+            if (buffer == null) throw new ArgumentNullException();
+            if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
+            if ((offset+count) > buffer.Length) throw new ArgumentException();
+            if (_isDisposed) throw new ObjectDisposedException("GZipStream");
+
+            GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
+            int result;
+            try
+            {
+                result = gzread(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
+                if (result < 0)
+                    throw new IOException();
+            }
+            finally
+            {
+                h.Free();
+            }
+            return result;
+        }
+
+        /// <summary>
+        /// Attempts to read a single byte from the stream.
+        /// </summary>
+        /// <returns>The byte that was read, or -1 in case of error or End-Of-File</returns>
+        public override int ReadByte()
+        {
+            if (!CanRead) throw new NotSupportedException();
+            if (_isDisposed) throw new ObjectDisposedException("GZipStream");
+            return gzgetc(_gzFile);
+        }
+
+        /// <summary>
+        /// Writes a number of bytes to the stream
+        /// </summary>
+        /// <param name="buffer"></param>
+        /// <param name="offset"></param>
+        /// <param name="count"></param>
+        /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
+        /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
+        /// <exception cref="ArgumentException">If <c>offset</c>  + <c>count</c> is &gt; buffer.Length</exception>
+        /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
+        /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
+        public override void Write(byte[] buffer, int offset, int count)
+        {
+            if (!CanWrite) throw new NotSupportedException();
+            if (buffer == null) throw new ArgumentNullException();
+            if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
+            if ((offset+count) > buffer.Length) throw new ArgumentException();
+            if (_isDisposed) throw new ObjectDisposedException("GZipStream");
+
+            GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
+            try
+            {
+                int result = gzwrite(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
+                if (result < 0)
+                    throw new IOException();
+            }
+            finally
+            {
+                h.Free();
+            }
+        }
+
+        /// <summary>
+        /// Writes a single byte to the stream
+        /// </summary>
+        /// <param name="value">The byte to add to the stream.</param>
+        /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
+        /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
+        public override void WriteByte(byte value)
+        {
+            if (!CanWrite) throw new NotSupportedException();
+            if (_isDisposed) throw new ObjectDisposedException("GZipStream");
+
+            int result = gzputc(_gzFile, (int)value);
+            if (result < 0)
+                throw new IOException();
+        }
+        #endregion
+
+        #region Position & length stuff
+        /// <summary>
+        /// Not supported.
+        /// </summary>
+        /// <param name="value"></param>
+        /// <exception cref="NotSupportedException">Always thrown</exception>
+        public override void SetLength(long value)
+        {
+            throw new NotSupportedException();
+        }
+
+        /// <summary>
+        ///  Not suppported.
+        /// </summary>
+        /// <param name="offset"></param>
+        /// <param name="origin"></param>
+        /// <returns></returns>
+        /// <exception cref="NotSupportedException">Always thrown</exception>
+        public override long Seek(long offset, SeekOrigin origin)
+        {
+            throw new NotSupportedException();
+        }
+
+        /// <summary>
+        /// Flushes the <c>GZipStream</c>.
+        /// </summary>
+        /// <remarks>In this implementation, this method does nothing. This is because excessive
+        /// flushing may degrade the achievable compression rates.</remarks>
+        public override void Flush()
+        {
+            // left empty on purpose
+        }
+
+        /// <summary>
+        /// Gets/sets the current position in the <c>GZipStream</c>. Not suppported.
+        /// </summary>
+        /// <remarks>In this implementation this property is not supported</remarks>
+        /// <exception cref="NotSupportedException">Always thrown</exception>
+        public override long Position
+        {
+            get
+            {
+                throw new NotSupportedException();
+            }
+            set
+            {
+                throw new NotSupportedException();
+            }
+        }
+
+        /// <summary>
+        /// Gets the size of the stream. Not suppported.
+        /// </summary>
+        /// <remarks>In this implementation this property is not supported</remarks>
+        /// <exception cref="NotSupportedException">Always thrown</exception>
+        public override long Length
+        {
+            get
+            {
+                throw new NotSupportedException();
+            }
+        }
+        #endregion
+    }
+}