Re: [PATCH] Remove incorrect special handling of /usr/libexec

[Stefano Brivio <sbrivio@redhat.com>]

On Mon, 26 Aug 2024 18:20:35 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Mon, Aug 26, 2024 at 09:55:47AM +0200, Stefano Brivio wrote:
> > On Mon, 26 Aug 2024 16:39:01 +1000
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >   
> > > The statement in the comment about /usr/libexec being only for running on
> > > other hosts simply isn't true, neither in practice nor according to the
> > > FHS spec[0].  
> > 
> > I don't remember where I took that meaning of /usr/libexec from, I
> > guess it's from some outdated packaging guidelines (Fedora? Kata
> > Containers?). Sure, it makes sense to fix that.
> >   
> > > Furthermore this logic didn't even handle it correctly, since
> > > it would only handle binaries _directly_ in /usr/libexec, not those in
> > > (explicitly FHS permitted) subdirectories under /usr/libexec.  
> > 
> > So, this change breaks the two cases I needed to cover with this, which
> > are /usr/libexec/kata-agent in general, and /usr/libexec/qemu-kvm on
> > RHEL 9.  
> 
> Huh.. why?

Because they're not in PATH on the guest, so we can't execute them.

As an alternative, we can unconditionally add /usr/libexec to it using
$FIXUP. I added the lines moving stuff to /usr/bin before I implemented
the $FIXUP mechanism, and I needed to run kata-agent as init.

But now that $FIXUP is available, that's probably less invasive.

> > What does it fix?  
> 
> I don't have a concrete case, but it would break anything where we're
> including this support binary, but the "front end" binary looks for it
> explicitly in /usr/libexec.  Which I'd kind of expect to be most
> support binary cases, since by design /usr/libexec won't generally be
> in the PATH.

I see. Well, given the limited time I can spend on maintaining mbuto,
I'd really prefer to just fix concrete issues, but this looks obvious
enough -- as long as we have another way to keep qemu-kvm usable in the
guest.

-- 
Stefano