How to Decompress nested GZip (TGZ) files in C#

Question

I am receiving a TGZ file that will contain one plain text file along with possibly one or more nested TGZ files. I have figured out how to decompress the main TGZ file and read the plain text file contained in it, but I have not been able to figure out how to recognize and decompress the nested TGZ files. Has anyone come across this problem before?

Also, I do not have control over the file I am receiving, so I cannot change the format of a TGZ file containing nested TGZ files. One other caveat (even though I don't think it matters) is that these files are being compressed and tarred in a Unix or Linux environment.

Thanks in advance for any help.

pierre · Accepted Answer · 2009-11-18 14:03:50Z

5

Try the SharpZipLib (http://www.icsharpcode.net/OpenSource/SharpZipLib/Download.aspx) free library.

It lets you work with TGZ and has methods to test files before trying to inflate them; so you can either rely on the file extensions being correct, or test them individually to see if you can read them as compressed files - then inflate them once the main file has been decompressed.

answered Nov 18, 2009 at 14:03

pierre

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5 Comments

Flahrty Over a year ago

Both this answer and Keith's answer handled the GZip portion, but the SharpZipLib could also handle the TAR file that was being compressed while I couldn't find a way for the DotNetZip library to handle the TAR file.

Cheeso Over a year ago

DotNetZip doesn't handle Tar archives. !!

Dan Bailiff Over a year ago

This is great for anyone willing to accept the GNU license! For the rest of us, is there another option?

SolarBear Over a year ago

@DanBailiff : for the record this might be new but they've added an exception to the GPL license which allows you to use it in commercial projects. Have a look at the License section of their page : icsharpcode.github.io/SharpZipLib

bwing Over a year ago

It appears this is now under the MIT license.

Cheeso · Accepted Answer · 2012-09-24 23:54:23Z

To read and write .tar and .tgz (or .tar.gz ) files from .NET, you can use this one-file tar class:

http://cheesoexamples.codeplex.com/SourceControl/changeset/view/97756#1868643

Very simple usage. To create an archive:

string[] filenames = { ... }; Ionic.Tar.CreateArchive("archive.tar", filenames);

Create a compressed (gzip'd) tar archive:

string[] filenames = { ... }; Ionic.Tar.CreateArchive("archive.tgz", filenames, TarOptions.Compress);

Read a tar archive:

var entries = Ionic.Tar.List("archive.tar"); // also handles .tgz files

Extract all entries in a tar archive:

var entries = Ionic.Tar.Extract("archive.tar"); // also handles .tgz files

The Tar.cs link is dead and I cannot find another. Could you provide a new one?
Yes, here is an active link: cheesoexamples.codeplex.com/SourceControl/changeset/view/… If you want to download a zip with the code, a readme, and a makefile, use this: cheesoexamples.codeplex.com/releases/view/76708
Will be fine to specify also directory to which extract all the content of tar archive.

Keith Sirmons · Accepted Answer · 2009-11-18 19:19:06Z

Take a look at DotNetZip on CodePlex.

"If all you want is a better DeflateStream or GZipStream class to replace the one that is built-into the .NET BCL, that is here, too. DotNetZip's DeflateStream and GZipStream are available in a standalone assembly, based on a .NET port of Zlib. These streams support compression levels and deliver much better performance that the built-in classes. There is also a ZlibStream to complete the set (RFC 1950, 1951, 1952)."

It appears that you can iterate through the compressed file and pull the individual files out of the archive. You can then test the files you uncompressed and see if any of them are themselves GZip files.

Here is a snippit from their Examples Page

using (ZipFile zip = ZipFile.Read(ExistingZipFile)) { foreach (ZipEntry e in zip) { e.Extract(OutputStream); } }

Keith

As of this writing (August 2015) DotNetZip seems to be an abandoned project with some major, unfixed bugs. From the looks of it I can't recommend using it.

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