shl: hook: add 'oneshot' flag

If an entry is marked as 'oneshot' then it will get deleted after it has
been called once. Note that the entry is unlinked _before_ the callback is
called.

If you use 'oneshot'-entries and normal entries with the same cb+data
combination, then you will probably get unexpected behavior. It is not
recommended to do that. In detail, you cannot control which entry is
deleted via a shl_hook_rm() call so you can never be sure whether the
oneshot entry or a normal entry is deleted.

Do not mix oneshot entries with normal entries!

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

src/eloop.c

@@ -2196,7 +2196,7 @@ int ev_eloop_register_signal_cb(struct ev_eloop *loop, int signum,
 			return ret;
 	}
 
-	ret = shl_hook_add_cast(sig->hook, cb, data);
+	ret = shl_hook_add_cast(sig->hook, cb, data, false);
 	if (ret) {
 		signal_free(sig);
 		return ret;
@@ -2257,7 +2257,7 @@ int ev_eloop_register_child_cb(struct ev_eloop *loop, ev_child_cb cb,
 		return -EINVAL;
 
 	empty = !shl_hook_num(loop->chlds);
-	ret = shl_hook_add_cast(loop->chlds, cb, data);
+	ret = shl_hook_add_cast(loop->chlds, cb, data, false);
 	if (ret)
 		return ret;
 
@@ -2311,7 +2311,7 @@ int ev_eloop_register_idle_cb(struct ev_eloop *eloop, ev_idle_cb cb,
 	if (!eloop)
 		return -EINVAL;
 
-	ret = shl_hook_add_cast(eloop->idlers, cb, data);
+	ret = shl_hook_add_cast(eloop->idlers, cb, data, false);
 	if (ret)
 		return ret;
 
@@ -2371,7 +2371,7 @@ int ev_eloop_register_pre_cb(struct ev_eloop *eloop, ev_idle_cb cb,
 	if (!eloop)
 		return -EINVAL;
 
-	return shl_hook_add_cast(eloop->pres, cb, data);
+	return shl_hook_add_cast(eloop->pres, cb, data, false);
 }
 
 /**
@@ -2420,7 +2420,7 @@ int ev_eloop_register_post_cb(struct ev_eloop *eloop, ev_idle_cb cb,
 	if (!eloop)
 		return -EINVAL;
 
-	return shl_hook_add_cast(eloop->posts, cb, data);
+	return shl_hook_add_cast(eloop->posts, cb, data, false);
 }
 
 /**

src/shl_hook.h

@@ -43,8 +43,8 @@ struct shl_hook;
 struct shl_hook_entry;
 typedef void (*shl_hook_cb) (void *parent, void *arg, void *data);
 
-#define shl_hook_add_cast(hook, cb, data) \
-	shl_hook_add((hook), (shl_hook_cb)(cb), (data))
+#define shl_hook_add_cast(hook, cb, data, oneshot) \
+	shl_hook_add((hook), (shl_hook_cb)(cb), (data), (oneshot))
 #define shl_hook_rm_cast(hook, cb, data) \
 	shl_hook_rm((hook), (shl_hook_cb)(cb), (data))
 
@@ -52,6 +52,7 @@ struct shl_hook_entry {
 	struct shl_dlist list;
 	shl_hook_cb cb;
 	void *data;
+	bool oneshot;
 };
 
 struct shl_hook {
@@ -110,7 +111,7 @@ static inline unsigned int shl_hook_num(struct shl_hook *hook)
 }
 
 static inline int shl_hook_add(struct shl_hook *hook, shl_hook_cb cb,
-			       void *data)
+			       void *data, bool oneshot)
 {
 	struct shl_hook_entry *entry;
 
@@ -123,14 +124,18 @@ static inline int shl_hook_add(struct shl_hook *hook, shl_hook_cb cb,
 	memset(entry, 0, sizeof(*entry));
 	entry->cb = cb;
 	entry->data = data;
+	entry->oneshot = oneshot;
 
 	shl_dlist_link_tail(&hook->entries, &entry->list);
 	hook->num++;
 	return 0;
 }
 
+/* This adds an entry only if it is not already in the list. But notice that if
+ * the entry is already registered twice or with a different \oneshot flag, the
+ * list will _not_ be changed! */
 static inline int shl_hook_add_single(struct shl_hook *hook, shl_hook_cb cb,
-				      void *data)
+				      void *data, bool oneshot)
 {
 	struct shl_hook_entry *entry;
 	struct shl_dlist *iter;
@@ -144,7 +149,7 @@ static inline int shl_hook_add_single(struct shl_hook *hook, shl_hook_cb cb,
 			return 0;
 	}
 
-	return shl_hook_add(hook, cb, data);
+	return shl_hook_add(hook, cb, data, oneshot);
 }
 
 static inline void shl_hook_rm(struct shl_hook *hook, shl_hook_cb cb,
@@ -204,9 +209,17 @@ static inline void shl_hook_call(struct shl_hook *hook, void *parent,
 	     hook->cur_entry != &hook->entries; ) {
 		entry = shl_dlist_entry(hook->cur_entry,
 					struct shl_hook_entry, list);
+		hook->cur_entry = entry->list.next;
+
+		if (entry->oneshot)
+			shl_dlist_unlink(&entry->list);
+
 		entry->cb(parent, arg, entry->data);
-		if (hook->cur_entry == &entry->list)
-			hook->cur_entry = hook->cur_entry->next;
+
+		if (entry->oneshot) {
+			free(entry);
+			--hook->num;
+		}
 	}
 
 	hook->cur_entry = NULL;

src/uterm_input.c

@@ -394,7 +394,7 @@ int uterm_input_register_cb(struct uterm_input *input,
 	if (!input || !cb)
 		return -EINVAL;
 
-	return shl_hook_add_cast(input->hook, cb, data);
+	return shl_hook_add_cast(input->hook, cb, data, false);
 }
 
 void uterm_input_unregister_cb(struct uterm_input *input,

src/uterm_video.c

@@ -324,7 +324,7 @@ int uterm_display_register_cb(struct uterm_display *disp, uterm_display_cb cb,
 	if (!disp)
 		return -EINVAL;
 
-	return shl_hook_add_cast(disp->hook, cb, data);
+	return shl_hook_add_cast(disp->hook, cb, data, false);
 }
 
 void uterm_display_unregister_cb(struct uterm_display *disp,
@@ -589,7 +589,7 @@ int uterm_video_register_cb(struct uterm_video *video, uterm_video_cb cb,
 	if (!video || !cb)
 		return -EINVAL;
 
-	return shl_hook_add_cast(video->hook, cb, data);
+	return shl_hook_add_cast(video->hook, cb, data, false);
 }
 
 void uterm_video_unregister_cb(struct uterm_video *video, uterm_video_cb cb,