client: Add wl_proxy_unref helper

Rather than open-coded decrement-and-maybe-free, introduce a
wl_proxy_unref helper to do this for us. This will come in useful for
future patches, where we may also have to free a zombie object.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Derek Foreman <derekf@osg.samsung.com>
Cc: Jonas Ådahl <jadahl@gmail.com>

src/wayland-client.c

diff --git a/src/wayland-client.c b/src/wayland-client.c
index 55838cd..f3d71b0 100644
--- a/src/wayland-client.c
+++ b/src/wayland-client.c
@@ -223,6 +223,19 @@
 }
 
 static void
+wl_proxy_unref(struct wl_proxy *proxy)
+{
+	assert(proxy->refcount > 0);
+	if (--proxy->refcount > 0)
+		return;
+
+	/* If we get here, the client must have explicitly requested
+	 * deletion. */
+	assert(proxy->flags & WL_PROXY_FLAG_DESTROYED);
+	free(proxy);
+}
+
+static void
 decrease_closure_args_refcount(struct wl_closure *closure)
 {
 	const char *signature;
@@ -241,10 +254,7 @@
 			if (proxy) {
 				if (proxy->flags & WL_PROXY_FLAG_DESTROYED)
 					closure->args[i].o = NULL;
-
-				proxy->refcount--;
-				if (!proxy->refcount)
-					free(proxy);
+				wl_proxy_unref(proxy);
 			}
 			break;
 		default:
@@ -257,20 +267,13 @@
 wl_event_queue_release(struct wl_event_queue *queue)
 {
 	struct wl_closure *closure;
-	struct wl_proxy *proxy;
 
 	while (!wl_list_empty(&queue->event_list)) {
 		closure = container_of(queue->event_list.next,
 				       struct wl_closure, link);
 		wl_list_remove(&closure->link);
-
 		decrease_closure_args_refcount(closure);
-
-		proxy = closure->proxy;
-		proxy->refcount--;
-		if (!proxy->refcount)
-			free(proxy);
-
+		wl_proxy_unref(closure->proxy);
 		wl_closure_destroy(closure);
 	}
 }
@@ -416,9 +419,7 @@
 
 	proxy->flags |= WL_PROXY_FLAG_DESTROYED;
 
-	proxy->refcount--;
-	if (!proxy->refcount)
-		free(proxy);
+	wl_proxy_unref(proxy);
 }
 
 /** Destroy a proxy object
@@ -1305,11 +1306,7 @@
 	decrease_closure_args_refcount(closure);
 	proxy = closure->proxy;
 	proxy_destroyed = !!(proxy->flags & WL_PROXY_FLAG_DESTROYED);
-
-	proxy->refcount--;
-	if (!proxy->refcount)
-		free(proxy);
-
+	wl_proxy_unref(proxy);
 	if (proxy_destroyed) {
 		wl_closure_destroy(closure);
 		return;