seat: Set keyboard if seat keyboard is NULL

sway sends wl_keyboard.enter on seat focus change and when a keyboard
active on a seat is configured. If all keyboards are removed and a
keyboard is added back without changing the focused client, no new
notify event would be sent despite having keyboard focus. This could
lead to key events without notify, which is a protocol violation.

As a quick fix, when configuring a keyboard on a seat where no keyboard
is currently active, activate the keyboard so that a focused surface
will receive a notify event.

Regressed by: e1b268af98edeb09e570e8855ef64f0719cbafe2
Closes: https://github.com/swaywm/sway/issues/7330

(cherry picked from commit 1ade0ce753dc5f588584f444ce80d27c3b1e4300)

1 files changed, 7 insertions, 0 deletions

diff --git a/sway/input/keyboard.c b/sway/input/keyboard.c
index aedf3ae6..c5a646c4 100644
--- a/sway/input/keyboard.c
+++ b/sway/input/keyboard.c
@@ -1068,6 +1068,13 @@ void sway_keyboard_configure(struct sway_keyboard *keyboard) {
                 }
         }
 
+        // If the seat has no active keyboard, set this one
+        struct wlr_seat *seat = keyboard->seat_device->sway_seat->wlr_seat;
+        struct wlr_keyboard *current_keyboard = seat->keyboard_state.keyboard;
+        if (current_keyboard == NULL) {
+                wlr_seat_set_keyboard(seat, keyboard->wlr);
+        }
+
         wl_list_remove(&keyboard->keyboard_key.link);
         wl_signal_add(&keyboard->wlr->events.key, &keyboard->keyboard_key);
         keyboard->keyboard_key.notify = handle_keyboard_key;