On Fri, Oct 9, 2020 at 1:35 PM Roman Perepelitsa <
roman.perepelitsa@gmail.com> wrote:

> On Fri, Oct 9, 2020 at 10:25 PM Bart Schaefer <schaefer@brasslantern.com>
> wrote:
> >
> > Er, sorry, this doesn't actually avoid the race, it just prevents the
> error message from being shown by whichever shell loses the race.
>
> I think this is the expected behavior. It's prescribed by POSIX for mkdir.
>
[...]

>
> The patch is incorrect for a different reason. If `zf_mkdir -p foo` is
> racing with another process that's doing `mkdir foo && rmdir foo`, the
> zf_mkdir call must never fail but with this patch it can fail.
>

Hm ... in that case the code shouldn't call stat() unless the mkdir() gives
EEXIST?  And then ignore ENOENT from stat()?

What if another process is doing "touch foo && rm foo"?  How is it possible
to distinguish that from mkdir+rmdir ?

Or are we confusing the requirements for mkdir(2) from those for mkdir(1)
?  I don't have the spec handy.