Fix keyboard shortcut handling inconsistencies

* Ensure that modifier keys are identified even when the next key does
  not produce a keysym. This requires that modifier change tracking
  be done for each sway_shortcut_state.

* Permit regular and --release shortcuts on the same key combination.
  Distinct bindings are identified for press and release cases; note
  that the release binding needs to be identified for both key press
  and key release events.

* Maintain ascending sort order for the shortcut state list, and keep
  track of the number of pressed key ids, for simpler (and hence
  faster) searching of the list of key bindings.

* Move binding duplicate detection into get_active_binding to avoid
  duplicating error messages.

1 files changed, 112 insertions, 94 deletions

diff --git a/sway/input/keyboard.c b/sway/input/keyboard.c
index d90655f2..9e093828 100644
--- a/sway/input/keyboard.c
+++ b/sway/input/keyboard.c
@@ -10,85 +10,111 @@
 #include "log.h"
 
 /**
+ * Remove all key ids associated to a keycode from the list of pressed keys
+ */
+static void state_erase_key(struct sway_shortcut_state *state,
+                uint32_t keycode) {
+        size_t j = 0;
+        for (size_t i = 0; i < state->npressed; ++i) {
+                if (i > j) {
+                        state->pressed_keys[j] = state->pressed_keys[i];
+                        state->pressed_keycodes[j] = state->pressed_keycodes[i];
+                }
+                if (state->pressed_keycodes[i] != keycode) {
+                        ++j;
+                }
+        }
+        while(state->npressed > j) {
+                --state->npressed;
+                state->pressed_keys[state->npressed] = 0;
+                state->pressed_keycodes[state->npressed] = 0;
+        }
+}
+
+/**
+ * Add a key id (with associated keycode) to the list of pressed keys,
+ * if the list is not full.
+ */
+static void state_add_key(struct sway_shortcut_state *state,
+                uint32_t keycode, uint32_t key_id) {
+        if (state->npressed >= SWAY_KEYBOARD_PRESSED_KEYS_CAP) {
+                return;
+        }
+        size_t i = 0;
+        while (i < state->npressed && state->pressed_keys[i] < key_id) {
+                ++i;
+        }
+        size_t j = state->npressed;
+        while (j > i) {
+                state->pressed_keys[j] = state->pressed_keys[j - 1];
+                state->pressed_keycodes[j] = state->pressed_keycodes[j - 1];
+                --j;
+        }
+        state->pressed_keys[i] = key_id;
+        state->pressed_keycodes[i] = keycode;
+        state->npressed++;
+}
+
+/**
  * Update the shortcut model state in response to new input
  */
 static void update_shortcut_state(struct sway_shortcut_state *state,
                 struct wlr_event_keyboard_key *event, uint32_t new_key,
-                bool last_key_was_a_modifier) {
+                uint32_t raw_modifiers) {
+        bool last_key_was_a_modifier = raw_modifiers != state->last_raw_modifiers;
+        state->last_raw_modifiers = raw_modifiers;
+
         if (event->state == WLR_KEY_PRESSED) {
-                if (last_key_was_a_modifier && state->last_key_index >= 0) {
+                if (last_key_was_a_modifier && state->last_keycode) {
                         // Last pressed key before this one was a modifier
-                        state->pressed_keycodes[state->last_key_index] = 0;
-                        state->pressed_keys[state->last_key_index] = 0;
-                        state->last_key_index = -1;
+                        state_erase_key(state, state->last_keycode);
                 }
 
                 // Add current key to set; there may be duplicates
-                for (size_t i = 0; i < SWAY_KEYBOARD_PRESSED_KEYS_CAP; ++i) {
-                        if (!state->pressed_keys[i]) {
-                                state->pressed_keys[i] = new_key;
-                                state->pressed_keycodes[i] = event->keycode;
-                                state->last_key_index = i;
-                                break;
-                        }
-                }
+                state_add_key(state, event->keycode, new_key);
+                state->last_keycode = event->keycode;
         } else {
-                for (size_t i = 0; i < SWAY_KEYBOARD_PRESSED_KEYS_CAP; ++i) {
-                        // The same keycode may match multiple keysyms.
-                        if (state->pressed_keycodes[i] == event->keycode) {
-                                state->pressed_keys[i] = 0;
-                                state->pressed_keycodes[i] = 0;
-                        }
-                }
+                state_erase_key(state, event->keycode);
         }
 }
 
 /**
- *
- * Returns a binding which matches the shortcut model state (ignoring the
- * `release` flag).
+ * If one exists, finds a binding which matches the shortcut model state,
+ * current modifiers, release state, and locked state.
  */
-static struct sway_binding *get_active_binding(
-                struct sway_shortcut_state *state, list_t *bindings,
-                uint32_t modifiers, bool locked) {
-        int npressed_keys = 0;
-        for (size_t i = 0; i < SWAY_KEYBOARD_PRESSED_KEYS_CAP; ++i) {
-                if (state->pressed_keys[i]) {
-                        ++npressed_keys;
-                }
-        }
+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) {
         for (int i = 0; i < bindings->length; ++i) {
                 struct sway_binding *binding = bindings->items[i];
 
                 if (modifiers ^ binding->modifiers ||
-                                npressed_keys != binding->keys->length ||
-                                locked > binding->locked) {
+                                state->npressed != (size_t)binding->keys->length ||
+                                locked > binding->locked ||
+                                release != binding->release) {
                         continue;
                 }
 
                 bool match = true;
-                for (int j = 0; j < binding->keys->length; ++j) {
+                for (size_t j = 0; j < state->npressed; j++) {
                         uint32_t key = *(uint32_t *)binding->keys->items[j];
-
-                        bool key_found = false;
-                        for (int k = 0; k < SWAY_KEYBOARD_PRESSED_KEYS_CAP; ++k) {
-                                if (state->pressed_keys[k] == key) {
-                                        key_found = true;
-                                        break;
-                                }
-                        }
-                        if (!key_found) {
+                        if (key != state->pressed_keys[j]) {
                                 match = false;
                                 break;
                         }
                 }
+                if (!match) {
+                        continue;
+                }
 
-                if (match) {
-                        return binding;
+                if (*current_binding && *current_binding != binding) {
+                        wlr_log(L_DEBUG, "encountered duplicate bindings %d and %d",
+                                        (*current_binding)->order, binding->order);
+                } else {
+                        *current_binding = binding;
                 }
+                return;
         }
-
-        return NULL;
 }
 
 /**
@@ -204,69 +230,65 @@ static void handle_keyboard_key(struct wl_listener *listener, void *data) {
         size_t raw_keysyms_len =
                 keyboard_keysyms_raw(keyboard, keycode, &raw_keysyms, &raw_modifiers);
 
-        struct wlr_input_device *device =
-                keyboard->seat_device->input_device->wlr_device;
-        uint32_t code_modifiers = wlr_keyboard_get_modifiers(device->keyboard);
-
-        bool last_key_was_a_modifier = code_modifiers != keyboard->last_modifiers;
-        keyboard->last_modifiers = code_modifiers;
+        uint32_t code_modifiers = wlr_keyboard_get_modifiers(wlr_device->keyboard);
 
         // Update shortcut model state
         update_shortcut_state(&keyboard->state_keycodes, event,
-                        (uint32_t)keycode, last_key_was_a_modifier);
+                        (uint32_t)keycode, code_modifiers);
         for (size_t i = 0; i < translated_keysyms_len; ++i) {
                 update_shortcut_state(&keyboard->state_keysyms_translated,
                                 event, (uint32_t)translated_keysyms[i],
-                                last_key_was_a_modifier && i == 0);
+                                code_modifiers);
         }
         for (size_t i = 0; i < raw_keysyms_len; ++i) {
                 update_shortcut_state(&keyboard->state_keysyms_raw,
                                 event, (uint32_t)raw_keysyms[i],
-                                last_key_was_a_modifier && i == 0);
+                                code_modifiers);
         }
 
-        // identify which binding should be executed.
-        struct sway_binding *binding = get_active_binding(
-                        &keyboard->state_keycodes,
-                        config->current_mode->keycode_bindings,
-                        code_modifiers, input_inhibited);
-        struct sway_binding *translated_binding = get_active_binding(
-                        &keyboard->state_keysyms_translated,
-                        config->current_mode->keysym_bindings,
-                        translated_modifiers, input_inhibited);
-        if (translated_binding && !binding) {
-                binding = translated_binding;
-        } else if (binding && translated_binding && binding != translated_binding) {
-                wlr_log(L_DEBUG, "encountered duplicate bindings %d and %d",
-                        binding->order, translated_binding->order);
-        }
-        struct sway_binding *raw_binding = get_active_binding(
-                        &keyboard->state_keysyms_raw,
-                        config->current_mode->keysym_bindings,
-                        raw_modifiers, input_inhibited);
-        if (raw_binding && !binding) {
-                binding = raw_binding;
-        } else if (binding && raw_binding && binding != raw_binding) {
-                wlr_log(L_DEBUG, "encountered duplicate bindings %d and %d",
-                        binding->order, raw_binding->order);
-        }
 
         bool handled = false;
 
-        // Execute the identified binding if need be.
-        if (keyboard->held_binding && binding != keyboard->held_binding &&
+        // Identify active release binding
+        struct sway_binding *binding_released = NULL;
+        get_active_binding(&keyboard->state_keycodes,
+                        config->current_mode->keycode_bindings, &binding_released,
+                        code_modifiers, true, input_inhibited);
+        get_active_binding(&keyboard->state_keysyms_translated,
+                        config->current_mode->keysym_bindings, &binding_released,
+                        translated_modifiers, true, input_inhibited);
+        get_active_binding(&keyboard->state_keysyms_raw,
+                        config->current_mode->keysym_bindings, &binding_released,
+                        raw_modifiers, true, input_inhibited);
+
+        // Execute stored release binding once no longer active
+        if (keyboard->held_binding && binding_released != keyboard->held_binding &&
                         event->state == WLR_KEY_RELEASED) {
                 keyboard_execute_command(keyboard, keyboard->held_binding);
                 handled = true;
         }
-        if (binding != keyboard->held_binding) {
+        if (binding_released != keyboard->held_binding) {
                 keyboard->held_binding = NULL;
         }
-        if (binding && event->state == WLR_KEY_PRESSED) {
-                if (binding->release) {
-                        keyboard->held_binding = binding;
-                } else {
-                        keyboard_execute_command(keyboard, binding);
+        if (binding_released && event->state == WLR_KEY_PRESSED) {
+                keyboard->held_binding = binding_released;
+        }
+
+        // Identify and execute active pressed binding
+        if (event->state == WLR_KEY_PRESSED) {
+                struct sway_binding *binding_pressed = NULL;
+                get_active_binding(&keyboard->state_keycodes,
+                                config->current_mode->keycode_bindings, &binding_pressed,
+                                code_modifiers, false, input_inhibited);
+                get_active_binding(&keyboard->state_keysyms_translated,
+                                config->current_mode->keysym_bindings, &binding_pressed,
+                                translated_modifiers, false, input_inhibited);
+                get_active_binding(&keyboard->state_keysyms_raw,
+                                config->current_mode->keysym_bindings, &binding_pressed,
+                                raw_modifiers, false, input_inhibited);
+
+                if (binding_pressed) {
+                        keyboard_execute_command(keyboard, binding_pressed);
                         handled = true;
                 }
         }
@@ -315,10 +337,6 @@ struct sway_keyboard *sway_keyboard_create(struct sway_seat *seat,
         wl_list_init(&keyboard->keyboard_key.link);
         wl_list_init(&keyboard->keyboard_modifiers.link);
 
-        keyboard->state_keycodes.last_key_index = -1;
-        keyboard->state_keysyms_raw.last_key_index = -1;
-        keyboard->state_keysyms_translated.last_key_index = -1;
-
         return keyboard;
 }