"Item with the same key has already been added" extracting tar with duplicate headers

[zarenner]

SharpZipLib fails to process a tar file that contains duplicate extended headers. Other tar programs (e.g. tar, 7-zip, SharpCompress) appear to handle this fine.

Steps to reproduce

1. Download https://registry.npmjs.org/jasmine-data-provider/-/jasmine-data-provider-2.2.0.tgz
2. gunzip (either with sharpziplib or other software)
3. Attempt to extract, read entries, or list contents of the tar:

using (var fs = File.OpenRead("c:\\jasmine-data-provider-2.2.0.tar"))
using (TarArchive tar = TarArchive.CreateInputTarArchive(fs))
{
    tar.ListContents();
}

Actual behavior

An item with the same key has already been added.
at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)   at ICSharpCode.SharpZipLib.Tar.TarExtendedHeaderReader.Read(Byte[] buffer, Int32 length)   at ICSharpCode.SharpZipLib.Tar.TarInputStream.GetNextEntry()   at ICSharpCode.SharpZipLib.Tar.TarArchive.ListContents()

Version of SharpZipLib

1.2.0

Obtained from (only keep the relevant lines)

• Package installed using NuGet

[Numpsy]

I tried debugging it and got:

Looks like TarExtendedHeaderReader treats every newline as the end of a header, and goes wrong if the value of a header itself contains a newline, rather than just taking the amount of data specified by the length field?

[piksel]

Whoa, yeah, this seems to be a lot deeper than simply duplicate headers.

[piksel]

Adding the file to the issue in case it gets moved: jasmine-data-provider-2.2.0.tar.gz

[zarenner]

Thanks for the analysis into the actual cause @Numpsy.