Solution to SharpZipLib issue #413

issue413.cs

using ICSharpCode.SharpZipLib.BZip2;
using System;
using System.Diagnostics;
using System.IO;

namespace Issue413
{
	class Program
	{
		static void Main(string[] args)
		{
			Console.WriteLine("SharpZipLib Issue 413\n");
			var sw = new Stopwatch();

			Console.WriteLine("Decompressing WITHOUT MultiStreams:");
			sw.Start();
			DecompressBZ2File(false, "naxos_US_2019-07-07-noMS.txt");
			sw.Stop();
			Console.WriteLine($"  Decompression time: {sw.ElapsedMilliseconds/1000.0:f3}s");

			Console.WriteLine();

			Console.WriteLine("Decompressing WITH MultiStreams:");
			sw.Restart();
			DecompressBZ2File(true, "naxos_US_2019-07-07-MS.txt");
			sw.Stop();
			Console.WriteLine($"  Decompression time: {sw.ElapsedMilliseconds / 1000.0:f3}s");
		}

		private static void DecompressBZ2File(bool multiStream, string txtFilePath)
		{
			string bz2FilePath = $"naxos_US_2019-07-07.txt.bz2";

			FileInfo zipFileName = new FileInfo(bz2FilePath);

			using (FileStream fileToDecompressAsStream = zipFileName.OpenRead())
			{
				using (FileStream decompressedStream = File.Create(txtFilePath))
				{
					try
					{
						Bzip2_Decompress(fileToDecompressAsStream, decompressedStream, true, multiStream);
						Console.WriteLine("  Successfully decompressed BZ2 file.");
					}
					catch (Exception ex)
					{
						Console.WriteLine($"  Error decompressing: {ex.GetType().Name}: {ex.Message}");
						Console.WriteLine($"  {ex.StackTrace.Replace("\n", "\n  ")}");
					}
				}
			}

			using var fs = File.OpenRead(txtFilePath);
			using var sr = new StreamReader(fs);

			var lines = 0L;
			while (sr.ReadLine() is string) lines++;

			Console.WriteLine($"  Output file size: {fs.Length} byte(s) ({lines} line(s))");
		}

		public static void Bzip2_Decompress(Stream inStream, Stream outStream, bool isStreamOwner, bool tryMultiStream)
		{
			if (inStream == null)
			{
				throw new ArgumentNullException(nameof(inStream));
			}
			if (outStream == null)
			{
				throw new ArgumentNullException(nameof(outStream));
			}

			try
			{
				long posBeforeRead;
				long bytesLeft;
				long bytesRead;

				do
				{
					posBeforeRead = inStream.Position;

					using (BZip2InputStream bzipInput = new BZip2InputStream(inStream))
					{
						bzipInput.IsStreamOwner = false;
						ICSharpCode.SharpZipLib.Core.StreamUtils.Copy(bzipInput, outStream, new byte[4096]);
					}

					bytesRead = inStream.Position - posBeforeRead;
					bytesLeft = inStream.Length - inStream.Position;

				} while (tryMultiStream && bytesRead > 0 && bytesLeft > 0);

			}
			finally
			{
				if (isStreamOwner)
				{
					inStream.Dispose();
					outStream.Dispose();
				}
			}
		}
	}
}