The Hardest Tarball?

A researcher created a deliberately ambiguous tar archive that extracts in eight different ways depending on which tool is used, exploiting ambiguities in how different tar utilities and libraries interpret POSIX specifications for hard links with explicit size values in pax headers. The archive uses a 512-byte size override on a hard link to create confusion about whether those bytes represent the link's data or the next file's header, resulting in varying behaviors across GNU tar, bsdtar, 7-Zip, Java Commons Compress, PHP, Ruby, R, and Haskell implementations.