[libvirt] [PATCHv2] build: add stubs so mdns code can be unconditionally compiled

[Eric Blake]

On 08/02/2012 04:11 AM, Daniel P. Berrange wrote:
> On Wed, Aug 01, 2012 at 05:52:42PM -0600, Eric Blake wrote:
>> The recent changes to test exported symbols flushed out the fact
>> that we were unconditionally linking against symbols that were
>> only conditionally compiled under HAVE_AVAHI.
>>
>> * src/Makefile.am (libvirt_net_rpc_server_la_SOURCES): Compile
>> virnetservermdns unconditionally.
>> * configure.ac (HAVE_AVAHI): Drop unused automake conditional.
>> * src/rpc/virnetservermdns.c: Add fallbacks when Avahi is not
>> present.
>>
>> ---
>>
>> Definitely more involved than splitting out a separate .syms file, so
>> I'm not sure whether this approach is better than the v1 approach.
>> But I did promise to propose this alternative, so here it is.  I tested
>> both with and without avahi development libraries present.
>>
>>  configure.ac               |  1 -
>>  src/Makefile.am            |  8 +---
>>  src/rpc/virnetservermdns.c | 98 ++++++++++++++++++++++++++++++++++++++++++----
>>  3 files changed, 91 insertions(+), 16 deletions(-)
> 
> Hmm, there should be a change to src/rpc/virnetserver.c to
> remove the avahi conditionals there I think.

I will have to do that as a followup patch; this patch made creation of
a new object always fail, but the virnetserver code assumes that if the
object creation call exists, then it is usable.  So it is not just a
trivial removal of #ifdef HAVE_AVAHI, but some actual changes to the
fallback code to be a useful no-op.

>  If everything
> still operates when avahi is disabled, then I think I prefer
> this patch, even though it is more complex, because it means
> the HAVE_AVAHI conditionals don't spread across the source
> tree to every user of this API.
> 
> ACK

I've gone ahead and pushed this, for build reasons, while working on the
followup.

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

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