Project Iso9660-compr

This project aims to provide a transparent compression scheme for ISO9660 (the format used on CDs), to be able to store larger amounts of data on a CD, providing the user with the illusion of a larger CD, instead of a CD containing many compressed files.

The current version is made up of
  • a modified gzip, able to produce the blockwise compression need for random access to data contained on a compressed file (necessary in the transparent compression scheme adopted here). This is enabled with the -B option.
  • a modified mkisofs, that, when called with the -z option, produces an ISO image with the necessary information to tell a modified kernel about transparently compressed files
  • a kernel patch (for Linux 2.2.18) to allow the kernel to transparently decompressed blockwisecompressed files.

The original blockwise compression extension of gzip was written by Eric Youngdale, modified extensively by Adam J. Richtero in 1998, and finally fixed by Roberto Di Cosmo in 2000/2001.

The mkisofs -z extension is due to Eric Youngdale.

The original kernel patch is (apparently) due to by Eric Youngdale, modified by Adam J. Richter. Roberto Di Cosmo fixed a fatal memory leak and changed the sructure of a compressed file to fix the problems caused by files that grow under gzip's action or by gzip's bugs.

Roberto Di Cosmo (E-mail:
Current version
1.0 [first public release, May 2001]