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Re: [libvirt] [PATCH] fix some XPath relative node resets



On Mon, Sep 28, 2009 at 05:19:12PM -0400, Laine Stump wrote:
> On 09/28/2009 11:30 AM, Daniel Veillard wrote:
>>   The virXPath... function take extra care to preserve the XPath context
>> node (ctxt->node) but in the case of virXPathString and virXPathBoolean
>> they forgot to do this on the error path. This patch fixes this and
>> move all ctxt->node = relnode instuctions just after the xmlXPathEval()
>> to make sure this doesn't happen if this code is modified.
>>    
>
> Daniel,
>
> I tried this patch with my tree, and it didn't change the behavior - in  
> virInterfaceDefParseProtoIPv4 if I find a dhcp node with
>
>     dhcp = virXPathNode(conn, "./dhcp", ctxt);
>
> any ip node will not be found with a subsequent
>
>         ip = virXPathNode(conn, "./ip", ctxt);
>
> (if dhcp comes back null, the ip node *is* found).
>
> However, if I first make the call to look for the ip node, and then do  
> the call for the dhcp node, both are found. Does that provide any clue  
> to you?

  I still think there is a problem with ctxt->node can you verify that
it's not modified by the all to parse Ip or Dhcp. I had a quick look
and that's how I spotted the problem, but could you check within gdb ?
>
> Also, you'll notice a new bit of code in virInterfaceDefParseIp:
>
>         tmp = virXPathString(conn, "string(./ip[1]/@source)", ctxt);
>
> For some reason, tmp always comes back null, even if my ip node looks  
> like the one in the example below:

  that mean that at the time you call virXPathString, then the
  ctxt->node is not pointing to the <protocol> element anymore.

> <interface type="ethernet" name="wlan0">
> <start mode="none"/>
> <mac address="00:1f:3c:9d:87:7c"/>
> <protocol family="ipv4">
> <dhcp/>
> <ip address="10.24.0.101" prefix="24" source="device"/>
> </protocol>
> </interface>

 I really think something changes ctxt->node in virXPath... or one of the
 subparsing routines.

Daniel

-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel veillard com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/


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