[libvirt] [PATCH V3 3/4] Extend NWFilter parameter parser to cope with lists of values

[Stefan Berger]

On 10/24/2011 12:31 PM, Matthias Bolte wrote:
> 2011/10/24 Stefan Berger<stefanb at linux.vnet.ibm.com>:
>> This patch modifies the NWFilter parameter parser to support multiple
>> elements with the same name and to internally build a list of items.
>> An example of the XML looks like this:
>>
>>         <parameter name='TEST' value='10.1.2.3'/>
>>         <parameter name='TEST' value='10.2.3.4'/>
>>         <parameter name='TEST' value='10.1.1.1'/>
>>
>> The list of values is then stored in the newly introduced data type
>> virNWFilterVarValue.
>>
>> The XML formatter is also adapted to print out all items in alphabetical
>> order sorted by 'name'.
>>
>> This patch als fixes a bug in the XML schema on the way.
>>
>> v3:
>>   - Follow Daniel Berrange's suggestion of parsing a list as shown above
>>   - Rewrote XML formatter to print out parameters in alphabetical order
> The parameters are stored in a hash and their name is used as key.
> This means that the parameters aren't guaranteed to be printed to XML
> again in the same order as they where parsed from XML, doesn't it?
>
> This might be no problem when all parameters have a unique name. But
> now with multiple parameters having the same name this might be an
> issue, assuming that a given element order has a meaning attached to
> it. If
>
>         <parameter name='TEST' value='10.1.2.3'/>
>         <parameter name='TEST' value='10.2.3.4'/>
>         <parameter name='TEST' value='10.1.1.1'/>
>
> and
>
>         <parameter name='TEST' value='10.1.1.1'/>
>         <parameter name='TEST' value='10.1.2.3'/>
>         <parameter name='TEST' value='10.2.3.4'/>
>
> aren't the same from the NWFilter's point-of-view then this needs to
> be fixed to have NWFilter preserve the exact order of elements.
>
> If it's the same then there's no problem here.
>
Internally there's an entry TEST in the hash table that holds the values 
in the order they were parsed (increasing index in a string array, 
char**). In the XML formatter the list is then printed in that same 
order. So the order is preserved and maybe some time in the future one 
could select a single value using $TEST[1] and be sure to always get 
that same value.

    Stefan