[Libguestfs] [PATCH] inspector: Fix virt-inspector on *BSD guests (RHBZ#1144138).

[Pino Toscano]

On Friday, 6 October 2017 12:11:08 CEST Richard W.M. Jones wrote:
> On Fri, Oct 06, 2017 at 09:53:27AM +0200, Pino Toscano wrote:
> > On Thursday, 5 October 2017 23:49:26 CEST Richard W.M. Jones wrote:
> > > On Thu, Oct 05, 2017 at 06:55:53PM +0200, Pino Toscano wrote:
> > > > On Thursday, 5 October 2017 17:36:09 CEST Richard W.M. Jones wrote:
> > > > >    /* We need to mount everything up in order to read out the list of
> > > > >     * applications and the icon, ie. everything below this point.
> > > > > +   *
> > > > > +   * XXX As a workaround for BSD guests, because the Linux kernel
> > > > > +   * driver cannot just mount a UFS filesystem, we must disable this
> > > > > +   * for all *BSD operating systems.  We cannot read the apps or icon
> > > > > +   * from *BSD anyway.
> > > > >     */
> > > > 
> > > > This is not true, libguestfs can actually read those properties.  The
> > > > proof of that is running virt-inspector with --no-applications, and
> > > > --no-icon shows the proper details (such as product name, mount points,
> > > > host name, etc) of the guest.
> > > 
> > > I'm a bit confused by this comment
> > 
> > I thought this was a workaround to the fact that mounting UFS partitions
> > can fail, without particular mount options:
> > 
> >   $ ./run virt-inspector -a freebsd-10.qcow2
> >   libguestfs: error: mount_ro: mount exited with status 32: mount: /sysroot: wrong fs type, bad option, bad superblock on /dev/sda2, missing codepage or helper program, or other error.
> 
> Correct.

As I said in my first reply to this email, this is the actual issue.

> > I do not see why we should special-case *BSD guests, since
> > at most (short of fixing the re-mount issue explained above) there will
> > be no information extracted.
> 
> This isn't correct.  With this patch, instead of virt-inspector
> printing nothing and failing with the mount error, you get the basic
> information:

As I said already, using --no-application & --no-icon gives already the
same; also, banning *BSD systems entirely from detailed inspections
means that:
a) whenever UFS is fixed, we will probably forget to remove this code
b) if UFS is not the filesystem used, then this issue does not happen
   at all, and just no extra information are returned (but this is a
   different issue)

Also, the problem is not specific to virt-inspector: any tool that
relies on inspection, and then mounts the partitions according to that,
will face the same issue -- e.g. virt-ls, virt-cat, virt-customize, etc.

That's why I do not think adding a workaround only in virt-inspector
makes much sense per-se, since it will not deal with general issue wrt
UFS partitions.

-- 
Pino Toscano
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