efs2tar is a tool that converts SGI EFS-formatted filesystem images (ie, the result of dd-ing a whole device in to a file) in to tarballs. It was based entirely on NetBSD's sys/fs/efs (source).
$ go install github.com/sophaskins/efs2tar
$ efs2tar -in ~/my-sgi-disc.iso -out ~/my-sgi-disc.tar
The Internet Archive has several discs in its collections that are formatted with EFS.
- any type of file other than directories and normal files (which is to say, links in particular do not work)
- partition layouts other than what you'd expect to see on an SGI-produced CDROM
- any sort of error handling...at all
- that includes verifying magic numbers
- preserving the original file permissions
- I've only tested this on like, one CD