Merge pull request #55 from dbuenor/dbueno/feature-add-gzipstream-ex-…

…to-framework

Added GZipStreamEx

HermaFx.Foundation/HermaFx.Foundation.csproj

@@ -68,6 +68,7 @@
     <Compile Include="Globalization\Currency.cs" />
     <Compile Include="Guard.cs" />
     <Compile Include="Guard.Expressions.cs" />
+    <Compile Include="IO\GZipStreamEx.cs" />
     <Compile Include="Reflection\Accessor.cs" />
     <Compile Include="Reflection\DummyPropertyInfo.cs" />
     <Compile Include="Reflection\PropertyChain.cs" />

HermaFx.Foundation/IO/GZipStreamEx.cs

@@ -0,0 +1,141 @@
+using System;
+using System.IO;
+using System.IO.Compression;
+
+namespace HermaFx.IO
+{
+	public class GZipStreamEx : Stream
+	{
+		#region constructor / cleanup
+
+		public GZipStreamEx(Stream inputStream, uint internalBufferSize, CompressionLevel compressionLevel = CompressionLevel.Fastest)
+		{
+			try
+			{
+				_inputStream = inputStream;
+				_outputStream = new MemoryStream((int)internalBufferSize);
+				_gZipStream = new GZipStream(_outputStream, compressionLevel, true);
+			}
+			catch
+			{
+				Cleanup();
+				throw;
+			}
+		}
+
+		private void Cleanup()
+		{
+			_gZipStream?.Dispose();
+			_outputStream?.Dispose();
+			_inputStream?.Dispose();
+		}
+
+		#endregion
+
+		#region private variables
+
+		private bool _endOfInputStreamReached = false;
+
+		private readonly Stream _inputStream;
+		private readonly MemoryStream _outputStream;
+		private readonly GZipStream _gZipStream;
+
+		#endregion
+
+		#region stream overrides
+
+		public override bool CanRead => true;
+
+		public override bool CanSeek => false;
+
+		public override bool CanWrite => false;
+
+		public override long Length => 0;
+
+		public override long Position
+		{
+			get
+			{
+				throw new NotSupportedException();
+			}
+			set
+			{
+				throw new NotSupportedException();
+			}
+		}
+
+		public override void SetLength(long value)
+		{
+			throw new NotSupportedException();
+		}
+
+		public override long Seek(long offset, SeekOrigin origin)
+		{
+			throw new NotSupportedException();
+		}
+
+		public override void Write(byte[] buffer, int offset, int count)
+		{
+			throw new NotSupportedException();
+		}
+
+		public override void Flush()
+		{
+			throw new NotSupportedException();
+		}
+
+		public override int Read(byte[] buffer, int offset, int count)
+		{
+			// 4k buffer size
+			var bufLength = count <= 4096 ? count : count / 4;
+			var buf = new byte[bufLength];
+
+			while ((_outputStream.Length < count) && !_endOfInputStreamReached)
+			{
+				var readCount = _inputStream.Read(buf, 0, buf.Length);
+				if (readCount == 0)
+				{
+					_endOfInputStreamReached = true;
+					_gZipStream.Flush();
+					_gZipStream.Dispose(); // because Flush() does not actually flush...
+					break;
+				}
+				else
+				{
+					_gZipStream.Write(buf, 0, readCount);
+				}
+			}
+
+			_outputStream.Position = 0;
+
+			var bytesRead = _outputStream.Read(buffer, offset, count);
+
+			if (_outputStream.Length > bytesRead)
+			{
+				// First we calculate how many bytes we should move to beggining.
+				var _remainingBytes = _outputStream.Length - bytesRead;
+				// We copy those remaining bytes to buf byte array.
+				_outputStream.Read(buf, 0, (int)_remainingBytes);
+				// We truncate outputStream to 0 length and set position to 0
+				_outputStream.SetLength(0);
+				// Then we copy those bytes to the 0 position for stream
+				_outputStream.Write(buf, 0, (int)_remainingBytes);
+			}
+			else
+			{
+				// We truncate outputStream to 0 length and set position to 0
+				_outputStream.SetLength(0);
+			}
+
+			return bytesRead;
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			base.Dispose(disposing);
+			if (disposing)
+				Cleanup();
+		}
+		#endregion
+	}
+}