wlroots/util/signal.c

#include "util/signal.h"

static void handle_noop(struct wl_listener *listener, void *data) {
	// Do nothing
}

void wlr_signal_emit_safe(struct wl_signal *signal, void *data) {
	struct wl_listener cursor;
	struct wl_listener end;

	/* Add two special markers: one cursor and one end marker. This way, we know
	 * that we've already called listeners on the left of the cursor and that we
	 * don't want to call listeners on the right of the end marker. The 'it'
	 * function can remove any element it wants from the list without troubles.
	 * wl_list_for_each_safe tries to be safe but it fails: it works fine
	 * if the current item is removed, but not if the next one is. */
	wl_list_insert(&signal->listener_list, &cursor.link);
	cursor.notify = handle_noop;
	wl_list_insert(signal->listener_list.prev, &end.link);
	end.notify = handle_noop;

	while (cursor.link.next != &end.link) {
		struct wl_list *pos = cursor.link.next;
		struct wl_listener *l = wl_container_of(pos, l, link);

		wl_list_remove(&cursor.link);
		wl_list_insert(pos, &cursor.link);

		l->notify(l, data);
	}

	wl_list_remove(&cursor.link);
	wl_list_remove(&end.link);
}