🚀 go-pugleaf

A. Hsiao writes:
>     I've just run dcheck for the
>first time on my hard drive (while I was waiting for a gopher
>search... it was on a whim.)
>
>     In any case, it picked up a lot of "Cluster $xxxx was previously
>allocated" and stated that my file structure was not intact.  I am
>assuming that this is caused by files linked across several
>directories, but want to verify this hypothesis, just in case there
>is something _seriously_ wrong with it.
>
>     OS9's directory structure doesn't mind linked files, does it?
>I've used them for some time now, saved a lot of space, but have
>never really had  occasion to try and copy or delete one of them.
>Have I made an os9 coup?

OS9 (or at least DCHECK, REPACK, and most other disk utilities) consider
a hard link to be a corruption of the file system - two directory entries
pointing at the same file descriptor sector. The data structures used by
RBF are "plumbed" for hard links (e.g. there's an FD.LNK field for the
link count in the file descriptor), but the implementation seems incomplete.

Since DCHECK is your only tool for finding "real" problems in the file
structure, you have three options: 1) don't use DCHECK, and risk data
loss; 2) keep a list of all of your hard links and cross-reference it
with the DCHECK output (e.g. DCHECK -BP); 3) don't use hard links.

Chris Burke