hook: zero hooks before adding them

Clear the hook before adding it so that we are sure the removed
callback doesn't contain garbage and cause a crash on disconnect.

Mark the removed and priv fields as private. Make sure to add the
removed callback after adding the hook.

Fixes a crash in kwin

spa/include/spa/utils/hook.h

@@ -70,7 +70,8 @@ struct spa_interface {
 struct spa_hook {
 	struct spa_list link;
 	struct spa_callbacks cb;
-	/** callback and data for the hook list */
+	/** callback and data for the hook list, private to the
+	  * hook_list implementor */
 	void (*removed) (struct spa_hook *hook);
 	void *priv;
 };
@@ -86,11 +87,12 @@ static inline bool spa_hook_list_is_empty(struct spa_hook_list *list)
 	return spa_list_is_empty(&list->list);
 }
 
-/** Append a hook \memberof spa_hook */
+/** Append a hook \memberof spa_hook. */
 static inline void spa_hook_list_append(struct spa_hook_list *list,
 					struct spa_hook *hook,
 					const void *funcs, void *data)
 {
+	spa_zero(*hook);
 	hook->cb = SPA_CALLBACKS_INIT(funcs, data);
 	spa_list_append(&list->list, &hook->link);
 }
@@ -100,6 +102,7 @@ static inline void spa_hook_list_prepend(struct spa_hook_list *list,
 					 struct spa_hook *hook,
 					 const void *funcs, void *data)
 {
+	spa_zero(*hook);
 	hook->cb = SPA_CALLBACKS_INIT(funcs, data);
 	spa_list_prepend(&list->list, &hook->link);
 }

spa/tests/test-utils.c

@@ -291,12 +291,12 @@ static void test_hook(void)
     spa_hook_list_init(&hl);
 
     h = malloc(sizeof(struct spa_hook));
-    h->removed = hook_removed_cb;
     spa_hook_list_append(&hl, h, &callbacks[1], &data);
+    h->removed = hook_removed_cb;
 
     h = malloc(sizeof(struct spa_hook));
-    h->removed = hook_removed_cb;
     spa_hook_list_append(&hl, h, &callbacks[2], &data);
+    h->removed = hook_removed_cb;
 
     /* iterate with the simple API */
     spa_hook_list_call_simple(&hl, struct my_hook, invoke, VERSION);
@@ -308,8 +308,8 @@ static void test_hook(void)
     memset(&data, 0, sizeof(struct my_hook_data));
 
     h = malloc(sizeof(struct spa_hook));
-    h->removed = hook_removed_cb;
     spa_hook_list_prepend(&hl, h, &callbacks[0], &data);
+    h->removed = hook_removed_cb;
 
     /* call only the first hook - this should be callback_1 */
     count = spa_hook_list_call_once(&hl, struct my_hook, invoke, VERSION);
@@ -323,8 +323,8 @@ static void test_hook(void)
 
     /* add callback_4 - this is version 1, so it shouldn't be executed */
     h = malloc(sizeof(struct spa_hook));
-    h->removed = hook_removed_cb;
     spa_hook_list_append(&hl, h, &callbacks[3], &data);
+    h->removed = hook_removed_cb;
 
     count = spa_hook_list_call(&hl, struct my_hook, invoke, VERSION);
     spa_assert(count == 3);

src/tests/test-endpoint.c

@@ -383,7 +383,6 @@ static void test_endpoint(void)
 	uint8_t buffer[1024];
 	struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, 1024);
 
-	spa_zero(d);
 	d.loop = pw_main_loop_new(NULL);
 	d.context = pw_context_new(pw_main_loop_get_loop(d.loop), NULL, 0);
 	spa_assert(d.context != NULL);