[Libvir] Re: Can't connect to lxc driver

[Daniel P. Berrange]

On Wed, Apr 30, 2008 at 05:22:22PM -0700, Dave Leskovec wrote:
> Hi Dan,
> 
> I updated today to the latest CVS and can no longer connect to the lxc driver.
> I've tracked it down to this check in doRemoteOpen() in remote_internal.c:
> 
>     if ((
> #ifdef HAVE_XMLURI_QUERY_RAW
>          uri->query_raw =
> #else
>          uri->query =
> #endif
>          qparam_get_query (vars)) == NULL) goto failed;
> 
> Looking at the recent VirBuffer changes, it looks like they changed the behavior
> of qparam_get_query.  With the old VirBuffer, qparam_get_query returned a
> non-NULL result because virBufferNew allocated space.  The new VirBuffer doesn't
> allocate space until something is added and hence this function returns NULL if
> nothing is ever put in the buffer.  I'm not familiar enough with the intended
> behavior to know what the fix should be here.

So two things - with the old code it was impossible for qparam_get_query
to return NULL, so the NULL check was redundant. Aside from that, it
looks like it is valid for uri->query to be set to NULL anway to indicate
that no variables are set. So I'd suggest you try just removing the
NULL check & goto failed. If that doesn't work, then modify get_query
to return "", if the buffer is NULL.

Regards,
Dan.
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