Re: RCS lock files

[Larry Jones]

Derek R. Price writes:
> 
> Are there any systems which will guarantee an atomic operation if the rename
> doesn't change the partition the file resides on?  Enough to justify a
> LockDirMode option or the like?  Or maybe this is something that could be
> tested for with configure?  I'm not sure how I'd go about that and I didn't
> find anything in a quick search of the Autoconf docs, but you never know.

On Unix-like systems, same filesystem (i.e., partition) is all that's
required; I don't know about other systems, though.  But given symbolic
links (and mount points, if anyone's crazy enough to do that) within the
repository, a LockDirMode option would seem to be pretty difficult.

On Unix-like systems you can limit writes to a single user (the owner of
the existing file) by setting the sticky bit on the directory, but of
course that affects all the files in the directory.  I've not used
systems with extensive ACL support, so I don't know if that would allow
more flexibility or not.  In any event, I haven't heard any outcry for
this feature.

-Larry Jones

I keep forgetting that rules are only for little nice people. -- Calvin