Re: curiosities with tempfile.active

[Jeff King <peff@peff.net>]

On Sat, Aug 27, 2022 at 02:47:45PM -0700, Chris Torek wrote:

> On Sat, Aug 27, 2022 at 6:05 AM Jeff King <peff@peff.net> wrote:
> > Yeah, I saw that. It's a bit vague, and if the call returns ENOSYS or
> > EISDIR, that would be perfectly fine. It's the "what happens on the
> > implementations that do support it..." part that I'm more worried about. :)
> 
> The history here is that pre-4.2BSD, Unix systems had no mkdir
> system call. You used mknod() to make a truly empty directory and
> the link() to create the "." and ".." entries within it, and all three of
> these operations were restricted to the super-user.  There was no
> rmdir either, so again, unlink() as the super-user was permitted to
> do the job (with three calls to unlink the "." and ".." entries first and
> then remove the directory).
> 
> Unlinking a directory when it still contains "." leaves the link count
> at 1 and there's no GC, so it sits around occupying an inode.

Thanks, that matches the sense of unease I had in the back of my mind. I
seem to recall that maybe older versions of SunOS exhibited this, but
that feels like a lifetime ago. At any rate, we should avoid that
unlink() call, and René's patch neatly does so.

-Peff