Re: utimensat EACCES vs. EPERM in 4.8+

[Carlos O'Donell <carlos-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On 01/16/2017 07:04 PM, Michael Kerrisk (man-pages) wrote:
> [CC += linux-api + Dave Chinner]

> Summary of the above list: there's a nontrivial risk that something in
> userspace got broken. (And just because we didn't hear about it yet
> doesn't mean it didn't happen; sometimes these reports only arrive
> many months or even years later.)
> 
> So, (1) I'm struggling to see the rationale for this change (I don't
> think "consistency" is enough) and (2) if "consistency" is the
> argument then (because the set of system calls in [1] are more
> frequently used than those in [2]), there's a reasonable argument that
> the change should have gone the other way: changing all IS_IMMUTABLE
> cases to fail with EACCES.
> 
> Summary: I think there's an argument for reverting the kernel patch.

Completely agree.

Even if you go ahead with these changes, they really should go through
some kind of distro verification [1]. If I even contemplated such a change
in glibc I'd run it through 4-6 months of Fedora Rawhide builds just to
see what breaks before putting it out in a real release (and we do this
frequently for thread-related changes).

-- 
Cheers,
Carlos.

[1] "Usage of Fedora Rawhide" https://fedoraproject.org/wiki/Glibc