How to decompose GZip (TGZ) file attachments in C #

Question

I get a TGZ file that will contain one simple text file along with possibly one or more nested TGZ files. I figured out how to unzip the main TGZ file and read the plain text file contained in it, but I could not figure out how to recognize and unzip the attached TGZ files. Has anyone encountered this problem before?

Also, I have no control over the file that I get, so I cannot change the format of the TGZ file containing the attached TGZ files. Another caveat (although I don’t think it matters) is that these files are compressed and downloaded to Unix or Linux.

Thanks in advance for your help.

Answer 1

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

It allows you to work with TGZ and has methods for checking files before trying to inflate them; so you can either rely on file extensions that are correct, or test them individually to see if you can read them as compressed files — then inflate them as soon as the main file is unpacked.

Answer 2

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

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

Very simple use. To create an archive:

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

Create a compressed (gzip'd) tarball:

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

Read the tar archive:

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

Extract all entries in the tar archive:

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

Answer 3

Check out DotNetZip on CodePlex.

“If all you want is better DeflateStream or GZipStream to replace the one that is built into .NET BCL, here it is. DotNetZip DeflateStream and GZipStream are available in a standalone .NET based assembly. Zlib port. Support for these compression level streams and better performance than the built-in classes. There is also ZlibStream to complete the suite (RFC 1950, 1951, 1952). "

It looks like you can iterate over a compressed file and pull individual files from the archive. You can then test the uncompressed files and see if they are the GZip files themselves.

Here is a snippet from Sample Pages

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

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