typedef gpointer AvahiCacheWalkCallback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, gpointer userdata);
gpointer avahi_cache_walk(AvahiCache *c, AvahiKey *pattern, AvahiCacheWalkCallback cb, gpointer userdata);
typedef gpointer AvahiCacheWalkCallback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, gpointer userdata);
gpointer avahi_cache_walk(AvahiCache *c, AvahiKey *pattern, AvahiCacheWalkCallback cb, gpointer userdata);