[libvirt] [PATCH v2 1/5] Internal refactory of data structures

[Eric Blake]

On 07/18/2012 10:31 AM, Michal Privoznik wrote:
> On 18.07.2012 03:28, Marcelo Cerri wrote:
>> This patch updates the structures that store information about each
>> domain and each hypervisor to support multiple security labels and
>> drivers. It also updates all the remaining code to use the new fields.
>> ---

> 
> We must update XML schema as well as we are going to allow more
> <model> and <doi> elements under <secmodel>. And maybe we want to add a test case. But that can be a follow up patch.

Absolutely add a testcase if you are enhancing the xml parser to accept
new tags.


> I think needs to be squashed in:
> 
> diff --git a/docs/schemas/capability.rng b/docs/schemas/capability.rng
> index 06ff685..be9d295 100644
> --- a/docs/schemas/capability.rng
> +++ b/docs/schemas/capability.rng

If you're going to touch docs/schemas, then it would also be nice to
touch the counterpart docs/*.html.in.  Unfortunately, I think our
capability.rng is currently underdocumented in the html.

> @@ -52,12 +52,14 @@
>  
>    <define name='secmodel'>
>      <element name='secmodel'>
> -      <element name='model'>
> -        <text/>
> -      </element>
> -      <element name='doi'>
> -        <text/>
> -      </element>
> +      <oneOrMore>
> +        <element name='model'>
> +          <text/>
> +        </element>
> +        <element name='doi'>
> +          <text/>
> +        </element>
> +      </oneOrMore>
>      </element>

Hmm, this says that:

<secmodel>
  <model>...</model>
  <doi>...</doi>
  <model>...</model>
  <doi>...</doi>
</secmodel>

will validate, but:

<secmodel>
  <doi>...</doi>
  <model>...</model>
  <model>...</model>
  <doi>...</doi>
</secmodel>

will not.  I think that's somewhat good (since the parameters are
positional, and we insist that they come in pairs, then the pairs must
be properly interleaved), but did the C code enforce that?

> 
> But don't we rather want multiple <secmodel> elements than multiple <doi> and <model> inside one <secmodel>?

Indeed - that makes the XML layout problem MUCH easier.  If we add an
<interleave> around the 'model' and 'doi' sub-elements, then you could
write:

<secmodel>
  <doi>...</doi>
  <model>...</model>
</secmodel>
<secmodel>
  <model>...</model>
  <doi>...</doi>
</secmodel>

and have an unambiguous 2-model design, without quite so much attention
being placed on the exactly-one 'doi' and 'model' subelement per 'secmodel'.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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