[libvirt] adding tests to qemu_driver

[Jiri Denemark]

On Fri, Nov 20, 2015 at 14:10:49 +0200, NoxDaFox wrote:
> 2015-11-19 14:25 GMT+02:00 Jiri Denemark <jdenemar at redhat.com>:
> 
> > On Fri, Nov 13, 2015 at 10:44:01 +0200, NoxDaFox wrote:
> > > 2015-11-13 0:30 GMT+02:00 Jiri Denemark <jdenemar at redhat.com>:
> > >
> > > > On Thu, Nov 12, 2015 at 23:47:54 +0200, noxdafox wrote:
> > > > > Greetings,
> > > > >
> > > > > I was investigating on an issue in which QEMU's dynamic ownership was
> > > > > not properly working when calling qemuDomainCoreDumpWithFormat().
> > > >
> > > > Could describe this issue you are investigating?
> > > >
> > >
> > > When calling qemuDomainCoreDumpWithFormat() the file is create as
> > root:root
> > > even when the dynamic ownership is specified in the qemu.conf
> > configuration
> > > file.
> >
> > And what is the result? Does dumping fail because of this or does it
> > work anyway?
> 
> The file gets dumped correctly, nevertheless it's ownership is still
> root:root and not the one set in the configuration.

OK, this is actually the correct behavior.

> >From qemu.conf
> 
> # Whether libvirt should dynamically change file ownership
> # to match the configured user/group above. Defaults to 1.
> # Set to 0 to disable file ownership changes.
> dynamic_ownership = 1
>
> Now, given a user and a group, when I run qemuDomainCoreDumpWithFormat() I
> get the file still belonging to root:root.

Right, but (even though the comment doesn't say so) this applies only to
files used by a running QEMU and only when they are used. They are
chowned to root:root (they'd ideally be changed back to the original
user/group, but we are no there yet) once they are no longer used. E.g.,
a disk image file will only be owned by the user/group while it is
attached to a running domain. When the domain is not running, they will
be owned by root:root.

> I tested the patch locally and it was working. I could create the file
> anywhere and the ownership was right.

Hmm, you are right, it looks like I didn't read the code carefully
enough. Anyway, the file should be owne by root:root so that other QEMU
processes cannot access it.

> What I'd like to do though, is to refactor the function as its logic
> is a bit cumbersome. Before that, I'll try to provide a set of tests
> to help me during the refactoring.

Oh sure, the code is a mess and if you have any idea for making saner
and more readable. Creating a test suite first is definitely a good
idea, because we don't want to accidentally change the behavior of this
ugly code.

Jirka