seat/dnd: support null drag icon surfaces

As per the Wayland spec [1]:

> The icon surface is an optional (can be NULL) surface that provides an
> icon to be moved around with the cursor.

However, as of now Sway "start_drag" signal handler does not starts the
DND session unless a non-NULL drag icons is provided. This patch fixes
it by skipping handling of the drag icon if it is null.

Fixes #5509

[1] https://wayland.freedesktop.org/docs/html/apa.html#protocol-spec-wl_data_device

Signed-off-by: Nick Diego Yamane <nickdiego@igalia.com>

1 files changed, 20 insertions, 22 deletions

diff --git a/sway/input/seat.c b/sway/input/seat.c
index 656e3e7e..bcf01962 100644
--- a/sway/input/seat.c
+++ b/sway/input/seat.c
@@ -470,31 +470,29 @@ static void handle_start_drag(struct wl_listener *listener, void *data) {
         wl_signal_add(&wlr_drag->events.destroy, &drag->destroy);
 
         struct wlr_drag_icon *wlr_drag_icon = wlr_drag->icon;
-        if (wlr_drag_icon == NULL) {
-                return;
-        }
-
-        struct sway_drag_icon *icon = calloc(1, sizeof(struct sway_drag_icon));
-        if (icon == NULL) {
-                sway_log(SWAY_ERROR, "Allocation failed");
-                return;
-        }
-        icon->seat = seat;
-        icon->wlr_drag_icon = wlr_drag_icon;
-        wlr_drag_icon->data = icon;
+        if (wlr_drag_icon != NULL) {
+                struct sway_drag_icon *icon = calloc(1, sizeof(struct sway_drag_icon));
+                if (icon == NULL) {
+                        sway_log(SWAY_ERROR, "Allocation failed");
+                        return;
+                }
+                icon->seat = seat;
+                icon->wlr_drag_icon = wlr_drag_icon;
+                wlr_drag_icon->data = icon;
 
-        icon->surface_commit.notify = drag_icon_handle_surface_commit;
-        wl_signal_add(&wlr_drag_icon->surface->events.commit, &icon->surface_commit);
-        icon->unmap.notify = drag_icon_handle_unmap;
-        wl_signal_add(&wlr_drag_icon->events.unmap, &icon->unmap);
-        icon->map.notify = drag_icon_handle_map;
-        wl_signal_add(&wlr_drag_icon->events.map, &icon->map);
-        icon->destroy.notify = drag_icon_handle_destroy;
-        wl_signal_add(&wlr_drag_icon->events.destroy, &icon->destroy);
+                icon->surface_commit.notify = drag_icon_handle_surface_commit;
+                wl_signal_add(&wlr_drag_icon->surface->events.commit, &icon->surface_commit);
+                icon->unmap.notify = drag_icon_handle_unmap;
+                wl_signal_add(&wlr_drag_icon->events.unmap, &icon->unmap);
+                icon->map.notify = drag_icon_handle_map;
+                wl_signal_add(&wlr_drag_icon->events.map, &icon->map);
+                icon->destroy.notify = drag_icon_handle_destroy;
+                wl_signal_add(&wlr_drag_icon->events.destroy, &icon->destroy);
 
-        wl_list_insert(&root->drag_icons, &icon->link);
+                wl_list_insert(&root->drag_icons, &icon->link);
 
-        drag_icon_update_position(icon);
+                drag_icon_update_position(icon);
+        }
         seatop_begin_default(seat);
 }