Re: directory sticky bit strangeness following libc6 update

On Sat, Apr 18, 2020 at 12:25:11PM +0200, Matthias Ferdinand wrote:
> On Fri, Apr 17, 2020 at 02:17:46PM -0500, Bob Tracy wrote:
> > (directory sticky bit handling strangeness)
> 
> it seems the difference lies in handling of O_CREAT.
> 
> (...)
> 
> not Alpha specific; this was done on x86_64 Ubuntu 20.04 beta:
> 
>     # uname -a; dpkg -l 'libc6' | grep ^.i
>     Linux xyz 5.4.0-24-generic #28-Ubuntu SMP Thu Apr 9 22:16:42 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
>     ii  libc6:amd64    2.31-0ubuntu7 amd64        GNU C Library: Shared libraries
> 
> 
> same kernel installed on an x86_64 Ubuntu 18.04, I get no "Permission denied":
> 
>     # uname -a; dpkg -l 'libc6' | grep ^.i
>     Linux xyz18 5.4.0-24-generic #28-Ubuntu SMP Thu Apr 9 22:16:42 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
>     ii  libc6:amd64    2.27-3ubuntu1 amd64        GNU C Library: Shared libraries
> 
> 
> So it seems not to be caused by the kernel version; strange how the same
> syscalls give different results depending on libc version.
> 
> If the rules had changed, it should not succeed even without
> O_CREAT. A bug?

That's *my* take on the matter.  It will be a day or so before I can
check upstream and see if any bug reports have been opened against
libc6, but if someone else would care to look in the meantime :-) ...

--Bob