Implement bindsym --to-code

* `bindsym --to-code` enables keysym to keycode translation.
* If there are no `xkb_layout` commands in the config file, the translation
uses the XKB_DEFAULT_LAYOUT value.
* It there is one or more `xkb_layout` command, the translation uses
the first one.
* If the translation is unsuccessful, a message is logged and the binding
is stored as BINDING_KEYSYM.
* The binding keysyms are stored and re-translated when a change in the input
configuration may affect the translated bindings.

include/sway/config.h

@@ -24,7 +24,6 @@ struct sway_variable {
 	char *value;
 };
 
-
 enum binding_input_type {
 	BINDING_KEYCODE,
 	BINDING_KEYSYM,
@@ -39,6 +38,7 @@ enum binding_flags {
 	BINDING_BORDER=4,    // mouse only; trigger on container border
 	BINDING_CONTENTS=8,  // mouse only; trigger on container contents
 	BINDING_TITLEBAR=16, // mouse only; trigger on container titlebar
+	BINDING_CODE=32,     // keyboard only; convert keysyms into keycodes
 };
 
 /**
@@ -50,6 +50,7 @@ struct sway_binding {
 	char *input;
 	uint32_t flags;
 	list_t *keys; // sorted in ascending order
+	list_t *syms; // sorted in ascending order; NULL if BINDING_CODE is not set
 	uint32_t modifiers;
 	char *command;
 };
@@ -406,6 +407,14 @@ enum alignment {
 	ALIGN_RIGHT
 };
 
+/**
+ * The keysym to keycode translation.
+ */
+struct keysym_translation_data {
+	struct xkb_keymap *xkb_keymap;
+	struct xkb_state *xkb_state;
+};
+
 /**
  * The configuration struct. The result of loading a config file.
  */
@@ -508,6 +517,9 @@ struct sway_config {
 	list_t *feature_policies;
 	list_t *ipc_policies;
 
+	// The keysym to keycode translation
+	struct keysym_translation_data keysym_translation;
+
 	// Context for command handlers
 	struct {
 		struct input_config *input_config;
@@ -617,12 +629,6 @@ bool spawn_swaybg(void);
 
 int workspace_output_cmp_workspace(const void *a, const void *b);
 
-int sway_binding_cmp(const void *a, const void *b);
-
-int sway_binding_cmp_qsort(const void *a, const void *b);
-
-int sway_binding_cmp_keys(const void *a, const void *b);
-
 void free_sway_binding(struct sway_binding *sb);
 
 void free_switch_binding(struct sway_switch_binding *binding);
@@ -651,6 +657,16 @@ void free_workspace_config(struct workspace_config *wsc);
  */
 void config_update_font_height(bool recalculate);
 
+/**
+ * Convert bindsym into bindcode using the first configured layout.
+ * Return false in case the conversion is unsuccessful.
+ */
+bool translate_binding(struct sway_binding *binding);
+
+void translate_keysyms(const char *layout);
+
+void binding_add_translated(struct sway_binding *binding, list_t *bindings);
+
 /* Global config singleton. */
 extern struct sway_config *config;
 

sway/commands/bind.c

@@ -24,6 +24,7 @@ void free_sway_binding(struct sway_binding *binding) {
 	}
 
 	list_free_items_and_destroy(binding->keys);
+	list_free_items_and_destroy(binding->syms);
 	free(binding->input);
 	free(binding->command);
 	free(binding);
@@ -249,14 +250,30 @@ static struct cmd_results *switch_binding_remove(
 			switchcombo);
 }
 
-static struct cmd_results *binding_add(struct sway_binding *binding,
-		list_t *mode_bindings, const char *bindtype,
-		const char *keycombo, bool warn) {
-	// overwrite the binding if it already exists
-	bool overwritten = false;
+/**
+ * Insert or update the binding.
+ * Return the binding which has been replaced or NULL.
+ */
+static struct sway_binding *binding_upsert(struct sway_binding *binding,
+		list_t *mode_bindings) {
 	for (int i = 0; i < mode_bindings->length; ++i) {
 		struct sway_binding *config_binding = mode_bindings->items[i];
 		if (binding_key_compare(binding, config_binding)) {
+			mode_bindings->items[i] = binding;
+			return config_binding;
+		}
+	}
+
+	list_add(mode_bindings, binding);
+	return NULL;
+}
+
+static struct cmd_results *binding_add(struct sway_binding *binding,
+		list_t *mode_bindings, const char *bindtype,
+		const char *keycombo, bool warn) {
+	struct sway_binding *config_binding = binding_upsert(binding, mode_bindings);
+
+	if (config_binding) {
 		sway_log(SWAY_INFO, "Overwriting binding '%s' for device '%s' "
 				"to `%s` from `%s`", keycombo, binding->input,
 				binding->command, config_binding->command);
@@ -267,13 +284,7 @@ static struct cmd_results *binding_add(struct sway_binding *binding,
 					config_binding->command);
 		}
 		free_sway_binding(config_binding);
-			mode_bindings->items[i] = binding;
-			overwritten = true;
-		}
-	}
-
-	if (!overwritten) {
-		list_add(mode_bindings, binding);
+	} else {
 		sway_log(SWAY_DEBUG, "%s - Bound %s to command `%s` for device '%s'",
 				bindtype, keycombo, binding->command, binding->input);
 	}
@@ -329,7 +340,6 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 	bool exclude_titlebar = false;
 	bool warn = true;
 
-	// Handle --release and --locked
 	while (argc > 0) {
 		if (strcmp("--release", argv[0]) == 0) {
 			binding->flags |= BINDING_RELEASE;
@@ -339,6 +349,10 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 			binding->flags |= BINDING_BORDER | BINDING_CONTENTS | BINDING_TITLEBAR;
 		} else if (strcmp("--border", argv[0]) == 0) {
 			binding->flags |= BINDING_BORDER;
+		} else if (strcmp("--to-code", argv[0]) == 0) {
+			if (!bindcode) {
+				binding->flags |= BINDING_CODE;
+			}
 		} else if (strcmp("--exclude-titlebar", argv[0]) == 0) {
 			exclude_titlebar = true;
 		} else if (strncmp("--input-device=", argv[0],
@@ -410,6 +424,12 @@ static struct cmd_results *cmd_bindsym_or_bindcode(int argc, char **argv,
 	// sort ascending
 	list_qsort(binding->keys, key_qsort_cmp);
 
+	// translate keysyms into keycodes
+	if (!translate_binding(binding)) {
+		sway_log(SWAY_INFO,
+				"Unable to translate bindsym into bindcode: %s", argv[0]);
+	}
+
 	list_t *mode_bindings;
 	if (binding->type == BINDING_KEYCODE) {
 		mode_bindings = config->current_mode->keycode_bindings;
@@ -566,3 +586,114 @@ void seat_execute_command(struct sway_seat *seat, struct sway_binding *binding)
 		ipc_event_binding(binding);
 	}
 }
+
+/**
+ * The last found keycode associated with the keysym
+ * and the total count of matches.
+ */
+struct keycode_matches {
+	xkb_keysym_t keysym;
+	xkb_keycode_t keycode;
+	int count;
+};
+
+/**
+ * Iterate through keycodes in the keymap to find ones matching
+ * the specified keysym.
+ */
+static void find_keycode(struct xkb_keymap *keymap,
+		xkb_keycode_t keycode, void *data) {
+	xkb_keysym_t keysym = xkb_state_key_get_one_sym(
+			config->keysym_translation.xkb_state, keycode);
+
+	if (keysym == XKB_KEY_NoSymbol) {
+		return;
+	}
+
+	struct keycode_matches *matches = data;
+	if (matches->keysym == keysym) {
+		matches->keycode = keycode;
+		matches->count++;
+	}
+}
+
+/**
+ * Return the keycode for the specified keysym.
+ */
+static struct keycode_matches get_keycode_for_keysym(xkb_keysym_t keysym) {
+	struct keycode_matches matches = {
+		.keysym = keysym,
+		.keycode = XKB_KEYCODE_INVALID,
+		.count = 0,
+	};
+
+	xkb_keymap_key_for_each(config->keysym_translation.xkb_keymap,
+			find_keycode, &matches);
+	return matches;
+}
+
+bool translate_binding(struct sway_binding *binding) {
+	if ((binding->flags & BINDING_CODE) == 0) {
+		return true;
+	}
+
+	switch (binding->type) {
+	// a bindsym to translate
+	case BINDING_KEYSYM:
+		binding->syms = binding->keys;
+		binding->keys = create_list();
+		break;
+	// a bindsym to re-translate
+	case BINDING_KEYCODE:
+		list_free_items_and_destroy(binding->keys);
+		binding->keys = create_list();
+		break;
+	default:
+		return true;
+	}
+
+	for (int i = 0; i < binding->syms->length; ++i) {
+		xkb_keysym_t *keysym = binding->syms->items[i];
+		struct keycode_matches matches = get_keycode_for_keysym(*keysym);
+
+		if (matches.count != 1) {
+			sway_log(SWAY_INFO, "Unable to convert keysym %d into"
+					" a single keycode (found %d matches)",
+					*keysym, matches.count);
+			goto error;
+		}
+
+		xkb_keycode_t *keycode = malloc(sizeof(xkb_keycode_t));
+		if (!keycode) {
+			sway_log(SWAY_ERROR, "Unable to allocate memory for a keycode");
+			goto error;
+		}
+
+		*keycode = matches.keycode;
+		list_add(binding->keys, keycode);
+	}
+
+	list_qsort(binding->keys, key_qsort_cmp);
+	binding->type = BINDING_KEYCODE;
+	return true;
+
+error:
+	list_free_items_and_destroy(binding->keys);
+	binding->type = BINDING_KEYSYM;
+	binding->keys = binding->syms;
+	binding->syms = NULL;
+	return false;
+}
+
+void binding_add_translated(struct sway_binding *binding,
+		list_t *mode_bindings) {
+	struct sway_binding *config_binding =
+		binding_upsert(binding, mode_bindings);
+
+	if (config_binding) {
+		sway_log(SWAY_INFO, "Overwriting binding for device '%s' "
+				"to `%s` from `%s`", binding->input,
+				binding->command, config_binding->command);
+		free_sway_binding(config_binding);
+	}
+}

sway/commands/input.c

@@ -39,6 +39,30 @@ static struct cmd_handler input_config_handlers[] = {
 	{ "xkb_numlock", input_cmd_xkb_numlock },
 };
 
+/**
+ * Re-translate keysyms if a change in the input config could affect them.
+ */
+static void retranslate_keysyms(struct input_config *input_config) {
+	bool matched = false;
+	for (int i = 0; i < config->input_configs->length; ++i) {
+		struct input_config *ic = config->input_configs->items[i];
+		matched |= ic->identifier == input_config->identifier;
+
+		// the first configured xkb_layout
+		if (ic->xkb_layout) {
+			if (matched) {
+				translate_keysyms(ic->xkb_layout);
+			}
+
+			// nothing has changed
+			return;
+		}
+	}
+
+	// no xkb_layout has been set, restore the default
+	translate_keysyms(getenv("XKB_DEFAULT_LAYOUT"));
+}
+
 struct cmd_results *cmd_input(int argc, char **argv) {
 	struct cmd_results *error = NULL;
 	if ((error = checkarg(argc, "input", EXPECTED_AT_LEAST, 2))) {
@@ -73,6 +97,7 @@ struct cmd_results *cmd_input(int argc, char **argv) {
 			store_input_config(config->handler_context.input_config);
 
 		input_manager_apply_input_config(ic);
+		retranslate_keysyms(ic);
 	} else {
 		free_input_config(config->handler_context.input_config);
 	}

sway/config.c

@@ -33,6 +33,31 @@
 
 struct sway_config *config = NULL;
 
+static struct keysym_translation_data new_keysym_translation_data(
+		const char *layout) {
+	struct xkb_rule_names rules = {
+		.layout = layout,
+	};
+
+	struct xkb_keymap *xkb_keymap = xkb_keymap_new_from_names(
+		xkb_context_new(XKB_CONTEXT_NO_FLAGS),
+		&rules,
+		XKB_KEYMAP_COMPILE_NO_FLAGS);
+
+	struct keysym_translation_data result = {
+		.xkb_keymap = xkb_keymap,
+		.xkb_state = xkb_state_new(xkb_keymap),
+	};
+
+	return result;
+}
+
+static void free_keysym_translation_data(
+		struct keysym_translation_data config) {
+	xkb_state_unref(config.xkb_state);
+	xkb_keymap_unref(config.xkb_keymap);
+}
+
 static void free_mode(struct sway_mode *mode) {
 	if (!mode) {
 		return;
@@ -146,6 +171,7 @@ void free_config(struct sway_config *config) {
 	free(config->swaynag_command);
 	free((char *)config->current_config_path);
 	free((char *)config->current_config);
+	free_keysym_translation_data(config->keysym_translation);
 	free(config);
 }
 
@@ -317,6 +343,9 @@ static void config_defaults(struct sway_config *config) {
 	if (!(config->feature_policies = create_list())) goto cleanup;
 	if (!(config->ipc_policies = create_list())) goto cleanup;
 
+	// The keysym to keycode translation
+	config->keysym_translation = new_keysym_translation_data(getenv("XKB_DEFAULT_LAYOUT"));
+
 	return;
 cleanup:
 	sway_abort("Unable to allocate config structures");
@@ -937,3 +966,50 @@ void config_update_font_height(bool recalculate) {
 		arrange_root();
 	}
 }
+
+static void translate_binding_list(list_t *bindings, list_t *bindsyms,
+		list_t *bindcodes) {
+	for (int i = 0; i < bindings->length; ++i) {
+		struct sway_binding *binding = bindings->items[i];
+		translate_binding(binding);
+
+		list_t *bindings;
+		switch (binding->type) {
+		case BINDING_KEYSYM:
+			bindings = bindsyms;
+			break;
+		case BINDING_KEYCODE:
+			bindings = bindcodes;
+			break;
+		default:
+			sway_assert(false, "unexpected translated binding type: %d",
+					binding->type);
+			break;
+		}
+
+		binding_add_translated(binding, bindings);
+	}
+}
+
+void translate_keysyms(const char *layout) {
+	free_keysym_translation_data(config->keysym_translation);
+	config->keysym_translation = new_keysym_translation_data(layout);
+
+	for (int i = 0; i < config->modes->length; ++i) {
+		struct sway_mode *mode = config->modes->items[i];
+
+		list_t *bindsyms = create_list();
+		list_t *bindcodes = create_list();
+
+		translate_binding_list(mode->keysym_bindings, bindsyms, bindcodes);
+		translate_binding_list(mode->keycode_bindings, bindsyms, bindcodes);
+
+		list_free(mode->keysym_bindings);
+		list_free(mode->keycode_bindings);
+
+		mode->keysym_bindings = bindsyms;
+		mode->keycode_bindings = bindcodes;
+	}
+
+	sway_log(SWAY_DEBUG, "Translated keysyms for layout %s", layout);
+}