Use pure C# to extract .tar and .tar.gz files

ExtractTarGz.cs

using System;
using System.IO;
using System.IO.Compression;
using System.Text;

namespace TarExample
{

	public class Tar
	{
		/// <summary>
		/// Extracts a <i>.tar.gz</i> archive to the specified directory.
		/// </summary>
		/// <param name="filename">The <i>.tar.gz</i> to decompress and extract.</param>
		/// <param name="outputDir">Output directory to write the files.</param>
		public static void ExtractTarGz(string filename, string outputDir)
		{
			using (var stream = File.OpenRead(filename))
				ExtractTarGz(stream, outputDir);
		}

		/// <summary>
		/// Extracts a <i>.tar.gz</i> archive stream to the specified directory.
		/// </summary>
		/// <param name="stream">The <i>.tar.gz</i> to decompress and extract.</param>
		/// <param name="outputDir">Output directory to write the files.</param>
		public static void ExtractTarGz(Stream stream, string outputDir)
		{
			// A GZipStream is not seekable, so copy it first to a MemoryStream
			using (var gzip = new GZipStream(stream, CompressionMode.Decompress))
			{
				const int chunk = 4096;
				using (var memStr = new MemoryStream())
				{
					int read;
					var buffer = new byte[chunk];
					do
					{
						read = gzip.Read(buffer, 0, chunk);
						memStr.Write(buffer, 0, read);
					} while (read == chunk);

					memStr.Seek(0, SeekOrigin.Begin);
					ExtractTar(memStr, outputDir);
				}
			}
		}

		/// <summary>
		/// Extractes a <c>tar</c> archive to the specified directory.
		/// </summary>
		/// <param name="filename">The <i>.tar</i> to extract.</param>
		/// <param name="outputDir">Output directory to write the files.</param>
		public static void ExtractTar(string filename, string outputDir)
		{
			using (var stream = File.OpenRead(filename))
				ExtractTar(stream, outputDir);
		}

		/// <summary>
		/// Extractes a <c>tar</c> archive to the specified directory.
		/// </summary>
		/// <param name="stream">The <i>.tar</i> to extract.</param>
		/// <param name="outputDir">Output directory to write the files.</param>
		public static void ExtractTar(Stream stream, string outputDir)
		{
			var buffer = new byte[100];
			while (true)
			{
				stream.Read(buffer, 0, 100);
				var name = Encoding.ASCII.GetString(buffer).Trim('\0');
				if (String.IsNullOrWhiteSpace(name))
					break;
				stream.Seek(24, SeekOrigin.Current);
				stream.Read(buffer, 0, 12);
				var size = Convert.ToInt64(Encoding.UTF8.GetString(buffer, 0, 12).Trim('\0').Trim(), 8);

				stream.Seek(376L, SeekOrigin.Current);

				var output = Path.Combine(outputDir, name);
				if (!Directory.Exists(Path.GetDirectoryName(output)))
					Directory.CreateDirectory(Path.GetDirectoryName(output));
                if (!name.Equals("./", StringComparison.InvariantCulture)) 
                {
                    using (var str = File.Open(output, FileMode.OpenOrCreate, FileAccess.Write))
                    {
                        var buf = new byte[size];
                        stream.Read(buf, 0, buf.Length);
                        str.Write(buf, 0, buf.Length);
                    }
                }

				var pos = stream.Position;
	
				var offset = 512 - (pos  % 512);
				if (offset == 512)
					offset = 0;

				stream.Seek(offset, SeekOrigin.Current);
			}
		}
	}
}

/*
    This software is available under 2 licenses -- choose whichever you prefer.
    ------------------------------------------------------------------------------
    ALTERNATIVE A - MIT License
    Copyright (c) 2017 Sean Barrett
    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
    of the Software, and to permit persons to whom the Software is furnished to do
    so, subject to the following conditions:
    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
    ------------------------------------------------------------------------------
    ALTERNATIVE B - Public Domain (www.unlicense.org)
    This is free and unencumbered software released into the public domain.
    Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
    software, either in source code form or as a compiled binary, for any purpose,
    commercial or non-commercial, and by any means.
    In jurisdictions that recognize copyright laws, the author or authors of this
    software dedicate any and all copyright interest in the software to the public
    domain. We make this dedication for the benefit of the public at large and to
    the detriment of our heirs and successors. We intend this dedication to be an
    overt act of relinquishment in perpetuity of all present and future rights to
    this software under copyright law.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

Hi,

1. Thanks for this script.
2. your cs file need a modification. In line 83. Instead of make this:

if (!name.Equals("./", StringComparison.InvariantCulture)) 

Please make this:

if(!name.EndsWith("/"))

I had tested on many files, and your original line fails, because you are trying to read directories as a file. Please make the change.

I also change the line 72:

if (String.IsNullOrWhiteSpace(name))

for

if(name != null && name!="")

This enables this file working also on NET Framework 2.0.
If you check my forked file, you can copy the changes, and I also normalized the tabs/whitespaces

I have tar file with structure like. i am not able to parse tar. Can anyone please help me to do that?

1. Tar File
   a) Folder
   I) csv1
   II) csv2
   III) csv3 etc.

Semicolon missing on end of line 76

Do you also know how to compress to a tar.gz? I've been trying to reverse your process to do so but have had no luck.

@Mpprobst
This is a very quick and dirty method of extraction, simply using offsets defined by the spec to grab the few pieces of information needed to extract the file's data from the stream. A full and proper implementation would define some structs, checksums, etc.

The TAR spec is actually fairly simple, it essentially just copies all of the input into a single stream, prepending each input with a basic header that it ensures begins on a specific byte boundary in the stream. In order for any other tool to be able to read the output, your would need to do a proper implementation and ensure the entire header is valid.

Luckily, the compression aspect of it using a GZip stream is already built-in to .NET, so it won't require anything complicated to convert a tar archive into a tar.gz one.

getting exception in line 40 when trying to decompress large files of 100MB

40 memStr.Write(buffer, 0, read);

getting exception in line 40 when trying to decompress large files of 100MB

40 memStr.Write(buffer, 0, read);

issue fixed https://gist.github.com/Su-s/438be493ae692318c73e30367cbc5c2a

ExtractTar use memory blocks for reading and writing. My tests showed 45% performance.

const int chunk = 2 * 1024 * 1024; //2MB var fbuf = new byte[chunk];

using (var str = File.Open(output, FileMode.OpenOrCreate, FileAccess.Write)) { int fbalance = size; int fread, fcount; while (true) { fcount = (fbuf.Length <= fbalance) ? fbuf.Length : fbalance; fread = stream.Read(fbuf, 0, fcount); if (fread <= 0) break; str.Write(fbuf, 0, fread); fbalance -= fread; } }

Excellent, just what I was looking for. I have wrapped this into a PowerShell function:

https://github.com/TheDotSource/Expand-TarBall/blob/main/Expand-TarBall.ps1

If you are using .NET 6 you should replace:

					do
					{
						read = gzip.Read(buffer, 0, chunk);
						memStr.Write(buffer, 0, read);
					} while (read == chunk);

with the following code:

                    while ((read = gzip.Read(buffer, 0, buffer.Length)) > 0)
                    {
	                    memStr.Write(buffer, 0, read);
                    }

This small code changes avoids writing a memory stream with only a few bytes in it and an endless loop in the ExtractTar method
Thanks for the inital snipped it really works great without using any dependencies

What license would you put this code under?

What license would you put this code under?

@voltagex I added choice of MIT or Public Domain, whichever you prefer. If neither of them suit your needs, I would have no problem with any exceptions. Free free to use/modify/sell the code as you see fit in any open/closed source project, commercial or otherwise, I don't require any credit.

If you are using .NET 6 you should replace:

					do
					{
						read = gzip.Read(buffer, 0, chunk);
						memStr.Write(buffer, 0, read);
					} while (read == chunk);

with the following code:

                    while ((read = gzip.Read(buffer, 0, buffer.Length)) > 0)
                    {
	                    memStr.Write(buffer, 0, read);
                    }

This small code changes avoids writing a memory stream with only a few bytes in it and an endless loop in the ExtractTar method Thanks for the inital snipped it really works great without using any dependencies

Thanks for this comment! This resolved my issue which proved very hard to debug.

I forked the snippet and made some style refactos and "modernizations" along with the fixes mentioned in the comments. This version works great on .NET 6

need this class i.e. GZipStream.cs which they used inside this file

@PRAKASHBADAM

need this class i.e. GZipStream.cs which they used inside this file

It's System.IO.Compression.GZipStream. If you don't have it, you should update your .net version.

System.IO.Compression.GZipStream It is one of the features that is introduced in .NET 7 https://devblogs.microsoft.com/dotnet/announcing-dotnet-7/ The above example should work with .NET 6 if you replace this: https://gist.github.com/ForeverZer0/a2cd292bd2f3b5e114956c00bb6e872b?permalink_comment_id=4071264#gistcomment-4071264 and with older versions (.NET Core 3) without that replacement

I found an edge case where this code crashes. We encountered a case where the name in the 512 byte header of a file was longer than 100 characters (bytes). These cases were handled for us by the use of a "fake file" called ././@LongLink with a typeTag of 'L'. This fake file's data contains the full filename that is larger than 100 bytes. So we need to read this first and temporarily hold onto it as we are about to read the ACTUAL real file in the next iteration. The real file's name is truncated to 100 characters but we will just skip those and use the full name we just read last iteration instead. This solved our problems. I updated my own forked gist with the fix here: https://gist.github.com/Matheos96/da8990030dfe3e27b0a48722042d9c0b