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Re: [Libguestfs] [PATCH 1/7] Push $desc creation into Sys::VirtConvert::Converter->convert



On Tue, Apr 26, 2011 at 05:03:46PM +0100, Matthew Booth wrote:
> @@ -934,21 +939,23 @@ sub _get_application_owner
>  
>  sub _unconfigure_hv
>  {
> -    my ($g, $desc) = @_;
> +    my ($g, $root, $desc) = @_;
>  
> -    _unconfigure_xen($g, $desc);
> -    _unconfigure_vmware($g, $desc);
> +    my @apps = $g->inspect_list_applications($root);

I can't tell without looking at the full context, but this might not
be safe.  inspect_list_applications will only work if the mountpoints
are all mounted up.  That's because this one call can read files out
of the filesystem, where as all the inspect_get_* calls just return
data that was cached in the handle (by inspect_os).

Note the comment in the removed code below which says just about
the same thing:

> -    my $root_dev = $roots[0];
> -
> -    # Mount up the disks.
> -    my %fses = $g->inspect_get_mountpoints ($root_dev);
> -    my @fses = sort { length $a <=> length $b } keys %fses;
> -    foreach (@fses) {
> -        eval { $g->mount_options ("", $fses{$_}, $_) };
> -        print __x("{e} (ignored)\n", e => $@) if $@;
> -    }
> -
> -    # Construct the "$desc" hashref which contains the main features
> -    # found by inspection.
> -    my %desc;
> -
> -    $desc{root_device} = $root_dev;
> -
> -    $desc{os} = $g->inspect_get_type ($root_dev);
> -    $desc{distro} = $g->inspect_get_distro ($root_dev);
> -    $desc{product_name} = $g->inspect_get_product_name ($root_dev);
> -    $desc{product_variant} = $g->inspect_get_product_variant ($root_dev);
> -    $desc{major_version} = $g->inspect_get_major_version ($root_dev);
> -    $desc{minor_version} = $g->inspect_get_minor_version ($root_dev);
> -    $desc{arch} = $g->inspect_get_arch ($root_dev);
> -
> -    # Notes:
> -    # (1) Filesystems have to be mounted for this to work.  Do not
> -    # move this code over the filesystem mounting code above.
> -    # (2) For RPM-based distros, new libguestfs inspection code
> -    # is only able to populate the 'app_name' field (old Perl code
> -    # populated a lot more).  Fortunately this is the only field
> -    # that the code currently uses.
> -    my @apps = $g->inspect_list_applications ($root_dev);
> -    $desc{apps} = \ apps;
> -
> -    return \%desc;
> +    return $roots[0];
>  }

References:
  http://libguestfs.org/guestfs.3.html#inspection
  http://libguestfs.org/guestfs.3.html#guestfs_inspect_list_applications

The rest seems all fine.  I'd be a lot happier if our language/
compiler was strongly type-checking all of these changes though ...

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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