yet another plan 9 page for Japanese

libolfs - lib overlay filesystem

/n/sources/contrib/kida/libolfs.tgz cryptfs.tgz

Plan 9's file server acts as resource manager. Resources are storage, process, network connection, etc. libolfs uses "name space tree" as the resource.

• overlay filesystem extends the base filesystem
• extend filesystem using regular call(read/write/open/create...)
• libolfs similar to lib9p, just override any routine.
• slow
• dirty model

Shortcomings are belonging to asymmetrical interface. libolfs act as filesystem using 9P. but use resouece (namespace) using systemcall.

of cource it is better using 9P both boundary. act as filesystem using 9P and use resource using 9P.

example: /n/sources/contrib/kida/libolfs.tgz cryptfs.tgz

term% mkdir /usr/foo/crypt
term% cryptfs /usr/foo/crypt
(use files)
term% kill cryptfs
(files are encrypted)

onlye encrypted data are stored rather than plain data. cryptfs act as filter layer doing encrypt/dectypt.

rot13fs is more clear and simply.

cryptfs main source code, rot13fs