Re: [libvirt] Fwd: libvirtd failing on MacOS in setgroups

[Marcus Furlong]

On Fri, 30 Aug 2019 at 21:33, Bruno Haible <address@hidden> wrote:
>
> Hi Eric,
>
> > I wonder if gnulib could provide a workaround setgroups() that overcomes
> > this issue
>
> I don't see how a workaround could look like. The problem is not the value
> of NGROUPS_MAX in user-space, but the same value NGROUPS_MAX in the kernel.
> More precisely, in the Darwin kernel file bsd/kern/kern_prot.c there is a
> function 'setgroups1', that contains the common implementation of the
> setgroups() and initgroups() system call, and this function fails with EINVAL
> if the number of groups in the set is > NGROUPS. In the kernel sources,
> NGROUPS is defined as NGROUPS_MAX, and NGROUPS_MAX is defined as 16.
>
> So, the situation on macOS has not changed since this page was written:
> https://www.j3e.de/ngroups.html
>
> What kind of workaround are you imagining? That we override open(),
> access(), eaccess() to call setgroups() first, in an intelligent way?
> That would be quite gross.
>
> For what purpose is libvirt or QEMU using setgroups()?

FWIW I compiled libvirt without the setgroups code on Mac and it
worked as expected. Not sure what the implications of that are though?

Marcus.

-- 
Marcus Furlong