Re: Anyone interested in implementing O_NOCLOBBER ?

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Fri, Apr 17, 2020 at 02:10:19AM +0700, Robert Elz wrote:
>     Date:        Thu, 16 Apr 2020 19:27:48 +0200
>     From:        Joerg Sonnenberger <joerg%bec.de@localhost>
>     Message-ID:  <20200416172748.GA86536%bec.de@localhost>
> 
>   | What is the point of this "restriction"? They wanted to make a set flag,
>   | but allow people to not have to use sub shells when also redirecting
>   | stderr?
> 
> Sorry, I'm not following the point there, what does any of this have
> to do with sub shells or stderr ?

I'm talking about the difference between this new clobber flag and
O_EXCL. As in: why doesn't the noclobber flag just set O_EXCL and done.
I really dislike such adhoc shell restrictions leaking into the kernel.
Actually, let me put the question differently. Why do we care about
TOCTOU here at all? As in: it seems reasonable to me to just do the
device check afterwards, potentially with O_NOFOLLOW. That would still
work in all reasonable situations for devices as they are generally not
in a world writable directory anway, so race conditions in that regard
are much less problematic.

Joerg