Archive::Tar is a useful library for working with tar archives from Perl. Unfortunately, one thing it doesn't allow is using data from memory as the archive. From the TODO section:

Allow archives to be passed in as string

Currently, we only allow opened filehandles or filenames, but not strings. The internals would need some reworking to facilitate stringified archives.

Fortunately, it does allow you to use a filehandle. I've previously mentioned about how useful the IO::Handle subsystem in perl is. And we should be able to use it in this case. The module we'll want is IO::String, which is a IO::Handle over a perl scalar. We can use it:

my $tar = new Archive::Tar(new IO::String($data));

Unfortunately when we run this now we get:

Cannot read compressed format in tar-mode at Foo.pm line 41
No data could be read from file at Foo.pm line 41

It turns out that this is because Archive::Tar uses IO::Zlib internally if the file isn't uncompressed, but this doesn't provide the ability to uncompress from a filehandle. The answer is to uncompress the data before passing it to Archive::Tar and the easiest way to do this is to use the IO::Uncompress::Gunzip module, so we can rewrite our code to:

my $tar = new Archive::Tar(new IO::Uncompress::Gunzip(new IO::String($data)));

Now when you run the script, Archive::Tar has an uncompressed tar stream. Yet another situation where IO::Handles comes to the rescue.