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

[Eric Blake]

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(-)

diff --git a/configure.ac b/configure.ac
index 400ac3b..e93bbb5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1248,7 +1248,6 @@ if test "x$with_avahi" = "xyes" || test "x$with_avahi" = "xcheck"; then
       [whether Avahi is used to broadcast server presense])
   fi
 fi
-AM_CONDITIONAL([HAVE_AVAHI], [test "x$with_avahi" = "xyes"])
 AC_SUBST([AVAHI_CFLAGS])
 AC_SUBST([AVAHI_LIBS])

diff --git a/src/Makefile.am b/src/Makefile.am
index b48ce65..8fbbabd 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1529,14 +1529,8 @@ libvirt_net_rpc_server_la_SOURCES = \
 	rpc/virnetserverprogram.h rpc/virnetserverprogram.c \
 	rpc/virnetserverservice.h rpc/virnetserverservice.c \
 	rpc/virnetserverclient.h rpc/virnetserverclient.c \
+	rpc/virnetservermdns.h rpc/virnetservermdns.c \
 	rpc/virnetserver.h rpc/virnetserver.c
-if HAVE_AVAHI
-libvirt_net_rpc_server_la_SOURCES += \
-	rpc/virnetservermdns.h rpc/virnetservermdns.c
-else
-EXTRA_DIST += \
-	rpc/virnetservermdns.h rpc/virnetservermdns.c
-endif
 libvirt_net_rpc_server_la_CFLAGS = \
 			$(AVAHI_CFLAGS) \
 			$(XDR_CFLAGS) \
diff --git a/src/rpc/virnetservermdns.c b/src/rpc/virnetservermdns.c
index 274be19..7c43c40 100644
--- a/src/rpc/virnetservermdns.c
+++ b/src/rpc/virnetservermdns.c
@@ -1,7 +1,7 @@
 /*
  * virnetservermdns.c: advertise server sockets
  *
- * Copyright (C) 2011 Red Hat, Inc.
+ * Copyright (C) 2011-2012 Red Hat, Inc.
  * Copyright (C) 2007 Daniel P. Berrange
  *
  * Derived from Avahi example service provider code.
@@ -29,14 +29,16 @@
 #include <stdio.h>
 #include <stdlib.h>

-#include <avahi-client/client.h>
-#include <avahi-client/publish.h>
+#if HAVE_AVAHI
+# include <avahi-client/client.h>
+# include <avahi-client/publish.h>

-#include <avahi-common/alternative.h>
-#include <avahi-common/simple-watch.h>
-#include <avahi-common/malloc.h>
-#include <avahi-common/error.h>
-#include <avahi-common/timeval.h>
+# include <avahi-common/alternative.h>
+# include <avahi-common/simple-watch.h>
+# include <avahi-common/malloc.h>
+# include <avahi-common/error.h>
+# include <avahi-common/timeval.h>
+#endif

 #include "virnetservermdns.h"
 #include "event.h"
@@ -55,18 +57,23 @@ struct _virNetServerMDNSEntry {

 struct _virNetServerMDNSGroup {
     virNetServerMDNSPtr mdns;
+#if HAVE_AVAHI
     AvahiEntryGroup *handle;
+#endif
     char *name;
     virNetServerMDNSEntryPtr entry;
     virNetServerMDNSGroupPtr next;
 };

 struct _virNetServerMDNS {
+#if HAVE_AVAHI
     AvahiClient *client;
     AvahiPoll *poller;
+#endif
     virNetServerMDNSGroupPtr group;
 };

+#if HAVE_AVAHI
 /* Avahi API requires this struct name in the app :-( */
 struct AvahiWatch {
     int watch;
@@ -612,3 +619,78 @@ void virNetServerMDNSEntryFree(virNetServerMDNSEntryPtr entry)
     VIR_FREE(entry->type);
     VIR_FREE(entry);
 }
+
+#else /* ! HAVE_AVAHI */
+
+static const char *unsupported = N_("avahi not available at build time");
+
+virNetServerMDNS *
+virNetServerMDNSNew(void)
+{
+    VIR_DEBUG("%s", _(unsupported));
+    return NULL;
+}
+
+int
+virNetServerMDNSStart(virNetServerMDNS *mdns ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+    return -1;
+}
+
+virNetServerMDNSGroupPtr
+virNetServerMDNSAddGroup(virNetServerMDNS *mdns ATTRIBUTE_UNUSED,
+                         const char *name ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+    return NULL;
+}
+
+void
+virNetServerMDNSRemoveGroup(virNetServerMDNSPtr mdns ATTRIBUTE_UNUSED,
+                            virNetServerMDNSGroupPtr group ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+virNetServerMDNSEntryPtr
+virNetServerMDNSAddEntry(virNetServerMDNSGroupPtr group ATTRIBUTE_UNUSED,
+                         const char *type ATTRIBUTE_UNUSED,
+                         int port ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+    return NULL;
+}
+
+void
+virNetServerMDNSRemoveEntry(virNetServerMDNSGroupPtr group ATTRIBUTE_UNUSED,
+                            virNetServerMDNSEntryPtr entry ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+void
+virNetServerMDNSStop(virNetServerMDNSPtr mdns ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+void
+virNetServerMDNSFree(virNetServerMDNSPtr mdns ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+void
+virNetServerMDNSGroupFree(virNetServerMDNSGroupPtr grp ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+void
+virNetServerMDNSEntryFree(virNetServerMDNSEntryPtr entry ATTRIBUTE_UNUSED)
+{
+    VIR_DEBUG("%s", _(unsupported));
+}
+
+#endif /* ! HAVE_AVAHI */
-- 
1.7.11.2