tarball don't really have a footer or header that contains info of all files. To add a file to a tarball, all you need is remove the end-of-file marker, append

tarball don't really have a footer or header that contains info of all files. To add a file to a tarball, all you need is remove the end-of-file marker, append to it and make a new marker. And that works extremely well with stream compressors (you just remake the last section).