CDfs is a file system for Linux systems that `exports' all tracks and boot images on a CD as normal files. These files can then be mounted (e.g. for ISO and boot images), copied, played (audio tracks), etc. The primary goal for developing this file system was to `unlock' information in old ISO sessions. The file system also allows you to access data on faulty multi session disks, e.g. disks with multiple single sessions instead of a multi session.
libburnia is a project comprised of libraries and binaries for reading, mastering, and writing optical discs. It provides libburn, a CD/DVD/BD burn library, libisofs, a manipulation library for ISO 9660 filesystems, and libisoburn, a ISO 9660 multi-session library. On top of them there is cdrskin, a cdrecord emulator, and xorriso, a all-in-one application for ISO 9660 multi-session operations which additionaly provides a limited emulation of mkisofs.