input: Add support for keyboard shortcuts inhibit

Adding support for the keyboard shortcuts inhibit protocol allows remote
desktop and virtualisation software to receive all keyboard input in
order to pass it through to their clients so users can fully interact
the their remote/virtual session. The software usually provides its own
key combination to release its "grab" to all keyboard input. The
inhibitor can be deactivated by the user by removing focus from the
surface using another input device such as the pointer.

Use support for the procotol in wlroots to add support to sway. Extend
the input manager with handlers for inhibitor creation and destruction
and appropriate bookkeeping. Attach the inhibitors to the seats they
apply to to avoid having to search the list of all currently existing
inhibitors on every keystroke and passing the inhibitor manager around.
Add a helper function to retrieve the inhibitor applying to the
currently focused surface of a seat, if one exists.

Extend bindsym with a flag for bindings that should be processed even if
an inhibitor is active. Conversely this disables all normal shortcuts if
an inhibitor is found for the currently focused surface in
keyboard::handle_key_event() since they don't have that flag set. Use
above helper function to determine if an inhibitor exists for the
surface that would eventually receive input.

Signed-off-by: Michael Weiser <michael.weiser@gmx.de>

3 files changed, 95 insertions, 9 deletions

diff --git a/sway/input/input-manager.c b/sway/input/input-manager.c
index 4cc07fe6..af0f5afa 100644
--- a/sway/input/input-manager.c
+++ b/sway/input/input-manager.c
@@ -296,6 +296,46 @@ static void handle_inhibit_deactivate(struct wl_listener *listener, void *data)
 	}
 }
 
+static void handle_keyboard_shortcuts_inhibitor_destroy(
+		struct wl_listener *listener, void *data) {
+	struct sway_keyboard_shortcuts_inhibitor *sway_inhibitor =
+		wl_container_of(listener, sway_inhibitor, destroy);
+
+	sway_log(SWAY_DEBUG, "Removing keyboard shortcuts inhibitor");
+
+	// sway_seat::keyboard_shortcuts_inhibitors
+	wl_list_remove(&sway_inhibitor->link);
+	wl_list_remove(&sway_inhibitor->destroy.link);
+	free(sway_inhibitor);
+}
+
+static void handle_keyboard_shortcuts_inhibit_new_inhibitor(
+		struct wl_listener *listener, void *data) {
+	struct sway_input_manager *input_manager =
+		wl_container_of(listener, input_manager,
+				keyboard_shortcuts_inhibit_new_inhibitor);
+	struct wlr_keyboard_shortcuts_inhibitor_v1 *inhibitor = data;
+
+	sway_log(SWAY_DEBUG, "Adding keyboard shortcuts inhibitor");
+
+	struct sway_keyboard_shortcuts_inhibitor *sway_inhibitor =
+		calloc(1, sizeof(struct sway_keyboard_shortcuts_inhibitor));
+	if (!sway_assert(sway_inhibitor, "could not allocate keyboard "
+				"shortcuts inhibitor")) {
+		return;
+	}
+	sway_inhibitor->inhibitor = inhibitor;
+
+	sway_inhibitor->destroy.notify = handle_keyboard_shortcuts_inhibitor_destroy;
+	wl_signal_add(&inhibitor->events.destroy, &sway_inhibitor->destroy);
+
+	// attach inhibitor to the seat it applies to
+	struct sway_seat *seat = inhibitor->seat->data;
+	wl_list_insert(&seat->keyboard_shortcuts_inhibitors, &sway_inhibitor->link);
+
+	wlr_keyboard_shortcuts_inhibitor_v1_activate(inhibitor);
+}
+
 void handle_virtual_keyboard(struct wl_listener *listener, void *data) {
 	struct sway_input_manager *input_manager =
 		wl_container_of(listener, input_manager, virtual_keyboard_new);
@@ -397,6 +437,13 @@ struct sway_input_manager *input_manager_create(struct sway_server *server) {
 	wl_signal_add(&input->inhibit->events.deactivate,
 			&input->inhibit_deactivate);
 
+	input->keyboard_shortcuts_inhibit =
+		wlr_keyboard_shortcuts_inhibit_v1_create(server->wl_display);
+	input->keyboard_shortcuts_inhibit_new_inhibitor.notify =
+		handle_keyboard_shortcuts_inhibit_new_inhibitor;
+	wl_signal_add(&input->keyboard_shortcuts_inhibit->events.new_inhibitor,
+			&input->keyboard_shortcuts_inhibit_new_inhibitor);
+
 	return input;
 }
 
diff --git a/sway/input/keyboard.c b/sway/input/keyboard.c
index 2cfcd126..9c5f190e 100644
--- a/sway/input/keyboard.c
+++ b/sway/input/keyboard.c
@@ -150,16 +150,18 @@ static bool update_shortcut_state(struct sway_shortcut_state *state,
  */
 static void get_active_binding(const struct sway_shortcut_state *state,
 		list_t *bindings, struct sway_binding **current_binding,
-		uint32_t modifiers, bool release, bool locked, const char *input,
-		bool exact_input, xkb_layout_index_t group) {
+		uint32_t modifiers, bool release, bool locked, bool inhibited,
+		const char *input, bool exact_input, xkb_layout_index_t group) {
 	for (int i = 0; i < bindings->length; ++i) {
 		struct sway_binding *binding = bindings->items[i];
 		bool binding_locked = (binding->flags & BINDING_LOCKED) != 0;
+		bool binding_inhibited = (binding->flags & BINDING_INHIBITED) != 0;
 		bool binding_release = binding->flags & BINDING_RELEASE;
 
 		if (modifiers ^ binding->modifiers ||
 				release != binding_release ||
 				locked > binding_locked ||
+				inhibited > binding_inhibited ||
 				(binding->group != XKB_LAYOUT_INVALID &&
 				 binding->group != group) ||
 				(strcmp(binding->input, input) != 0 &&
@@ -195,6 +197,8 @@ static void get_active_binding(const struct sway_shortcut_state *state,
 
 			bool current_locked =
 				((*current_binding)->flags & BINDING_LOCKED) != 0;
+			bool current_inhibited =
+				((*current_binding)->flags & BINDING_INHIBITED) != 0;
 			bool current_input = strcmp((*current_binding)->input, input) == 0;
 			bool current_group_set =
 				(*current_binding)->group != XKB_LAYOUT_INVALID;
@@ -203,6 +207,7 @@ static void get_active_binding(const struct sway_shortcut_state *state,
 
 			if (current_input == binding_input
 					&& current_locked == binding_locked
+					&& current_inhibited == binding_inhibited
 					&& current_group_set == binding_group_set) {
 				sway_log(SWAY_DEBUG,
 						"Encountered conflicting bindings %d and %d",
@@ -224,11 +229,21 @@ static void get_active_binding(const struct sway_shortcut_state *state,
 					current_locked == locked) {
 				continue; // Prefer correct lock state for matching input+group
 			}
+
+			if (current_input == binding_input &&
+					current_group_set == binding_group_set &&
+					current_locked == binding_locked &&
+					current_inhibited == inhibited) {
+				// Prefer correct inhibition state for matching
+				// input+group+locked
+				continue;
+			}
 		}
 
 		*current_binding = binding;
 		if (strcmp((*current_binding)->input, input) == 0 &&
 				(((*current_binding)->flags & BINDING_LOCKED) == locked) &&
+				(((*current_binding)->flags & BINDING_INHIBITED) == inhibited) &&
 				(*current_binding)->group == group) {
 			return; // If a perfect match is found, quit searching
 		}
@@ -328,6 +343,9 @@ static void handle_key_event(struct sway_keyboard *keyboard,
 	bool exact_identifier = wlr_device->keyboard->group != NULL;
 	seat_idle_notify_activity(seat, IDLE_SOURCE_KEYBOARD);
 	bool input_inhibited = seat->exclusive_client != NULL;
+	struct sway_keyboard_shortcuts_inhibitor *sway_inhibitor =
+		keyboard_shortcuts_inhibitor_get_for_focused_surface(seat);
+	bool shortcuts_inhibited = sway_inhibitor && sway_inhibitor->inhibitor->active;
 
 	// Identify new keycode, raw keysym(s), and translated keysym(s)
 	xkb_keycode_t keycode = event->keycode + 8;
@@ -364,15 +382,18 @@ static void handle_key_event(struct sway_keyboard *keyboard,
 	struct sway_binding *binding_released = NULL;
 	get_active_binding(&keyboard->state_keycodes,
 			config->current_mode->keycode_bindings, &binding_released,
-			code_modifiers, true, input_inhibited, device_identifier,
+			code_modifiers, true, input_inhibited,
+			shortcuts_inhibited, device_identifier,
 			exact_identifier, keyboard->effective_layout);
 	get_active_binding(&keyboard->state_keysyms_raw,
 			config->current_mode->keysym_bindings, &binding_released,
-			raw_modifiers, true, input_inhibited, device_identifier,
+			raw_modifiers, true, input_inhibited,
+			shortcuts_inhibited, device_identifier,
 			exact_identifier, keyboard->effective_layout);
 	get_active_binding(&keyboard->state_keysyms_translated,
 			config->current_mode->keysym_bindings, &binding_released,
-			translated_modifiers, true, input_inhibited, device_identifier,
+			translated_modifiers, true, input_inhibited,
+			shortcuts_inhibited, device_identifier,
 			exact_identifier, keyboard->effective_layout);
 
 	// Execute stored release binding once no longer active
@@ -393,17 +414,19 @@ static void handle_key_event(struct sway_keyboard *keyboard,
 	if (event->state == WLR_KEY_PRESSED) {
 		get_active_binding(&keyboard->state_keycodes,
 				config->current_mode->keycode_bindings, &binding,
-				code_modifiers, false, input_inhibited, device_identifier,
+				code_modifiers, false, input_inhibited,
+				shortcuts_inhibited, device_identifier,
 				exact_identifier, keyboard->effective_layout);
 		get_active_binding(&keyboard->state_keysyms_raw,
 				config->current_mode->keysym_bindings, &binding,
-				raw_modifiers, false, input_inhibited, device_identifier,
+				raw_modifiers, false, input_inhibited,
+				shortcuts_inhibited, device_identifier,
 				exact_identifier, keyboard->effective_layout);
 		get_active_binding(&keyboard->state_keysyms_translated,
 				config->current_mode->keysym_bindings, &binding,
 				translated_modifiers, false, input_inhibited,
-				device_identifier, exact_identifier,
-				keyboard->effective_layout);
+				shortcuts_inhibited, device_identifier,
+				exact_identifier, keyboard->effective_layout);
 	}
 
 	// Set up (or clear) keyboard repeat for a pressed binding. Since the
diff --git a/sway/input/seat.c b/sway/input/seat.c
index 371de56e..6739c163 100644
--- a/sway/input/seat.c
+++ b/sway/input/seat.c
@@ -557,6 +557,7 @@ struct sway_seat *seat_create(const char *seat_name) {
 		handle_request_set_primary_selection;
 
 	wl_list_init(&seat->keyboard_groups);
+	wl_list_init(&seat->keyboard_shortcuts_inhibitors);
 
 	wl_list_insert(&server.input->seats, &seat->link);
 
@@ -1473,3 +1474,18 @@ void seatop_render(struct sway_seat *seat, struct sway_output *output,
 bool seatop_allows_set_cursor(struct sway_seat *seat) {
 	return seat->seatop_impl->allow_set_cursor;
 }
+
+struct sway_keyboard_shortcuts_inhibitor *
+keyboard_shortcuts_inhibitor_get_for_focused_surface(
+		const struct sway_seat *seat) {
+	struct wlr_surface *focused_surface =
+		seat->wlr_seat->keyboard_state.focused_surface;
+	struct sway_keyboard_shortcuts_inhibitor *sway_inhibitor = NULL;
+	wl_list_for_each(sway_inhibitor, &seat->keyboard_shortcuts_inhibitors, link) {
+		if (sway_inhibitor->inhibitor->surface == focused_surface) {
+			return sway_inhibitor;
+		}
+	}
+
+	return NULL;
+}