Creating a tar.gz with respect to symlinks

[TylerMizuyabu]

Hello, I'm currently trying to use this library to create a .tar.gz of a user's local workspace. This workspace may or may not contain symlinks, and ideally I want to preserve all symlinks that link to folder/files within the local workspace. Currently when I try to do this with code like the following:

FileStream outStream = File.Create("workspace.tar.gz");
Stream gzoStream = new GZipOutputStream(outStream);
TarArchive tarArchive = TarArchive.CreateOutputTarArchive(gzoStream);
foreach (FileInfo info in fileInfos)
{
		tarArchive.WriteEntry(TarEntry.CreateEntryFromFile(info.FullName), false);
}

The symlink file does not get preserved. Instead one of the following two things happen:

1. If the symlink targets a file, I get an error because the size field within the header does not match the actual size of the targeted file.
2. If the symlink targets a directory, the target directory gets added to the tarArchive but not the symlink.

Is there a way I can add the symlink itself to the archive?

[piksel]

Yes, but you would need to identify the link yourself (no built-in way to detect symlinks in .NET if I recall see edit) and add an entry using something like this:

foreach (FileInfo info in fileInfos)
{
	if (isSymlink(info, out var target)) 
    {
        var tarEntry = TarEntry.CreateTarEntry(info.FullName);
        tarEntry.TarHeader.LinkName = target;
        tarEntry.TarHeader.TypeFlag = TarHeader.LF_SYMLINK;
        tarArchive.WriteEntry(tarEntry, false);
    } 
    else 
    {
		tarArchive.WriteEntry(TarEntry.CreateEntryFromFile(info.FullName), false);
    }
}

Edit: Actually, since .NET 6 it is now possible to work with symlinks and unix permissions, so perhaps support for this ought to be (finally) added to TarArchive.

[TylerMizuyabu]

Added an additional call to entry.GetFileTarHeader(entry.TarHeader, info.FullName); because the WriteEntry function was complaining that the tar entry's File property was null and it works well for symlinks that target directories. However it still produces the error request to write '69' bytes exceeds size in header of '10' bytes (Parameter 'count') for symlinks that target files.

I'm guessing the the file.OpenRead call in the tar archive's WriteEntryCore method is opening up a stream to the target file so there is still a mismatch between the length it expects and the length of the content it is reading from. Is there additional configuration I am missing or perhaps the additional call to GetFileTarHeader was incorrect?

[piksel]

Perhaps you can clear the file size manually using tarEntry.TarHeader.Size (or equivalent property, I'm on mobile right now). Otherwise this might actually not be possible. I will take a look as soon as I get time!