Implement input_cmd_xkb_file (swaywm#3999)

Adds a new commend "xkb_file", which constructs the internal
xkb_keymap from a xkb file rather than an RMLVO configuration.
This allows greater flexibility when specifying xkb configurations.
An xkb file can be dumped with the xkbcomp program.

include/sway/commands.h

@@ -257,6 +257,7 @@ sway_cmd input_cmd_scroll_method;
 sway_cmd input_cmd_tap;
 sway_cmd input_cmd_tap_button_map;
 sway_cmd input_cmd_xkb_capslock;
+sway_cmd input_cmd_xkb_file;
 sway_cmd input_cmd_xkb_layout;
 sway_cmd input_cmd_xkb_model;
 sway_cmd input_cmd_xkb_numlock;

include/sway/config.h

@@ -138,6 +138,7 @@ struct input_config {
 	char *xkb_options;
 	char *xkb_rules;
 	char *xkb_variant;
+	char *xkb_file;
 
 	int xkb_numlock;
 	int xkb_capslock;

sway/commands/input.c

@@ -28,6 +28,7 @@ static struct cmd_handler input_handlers[] = {
 	{ "scroll_method", input_cmd_scroll_method },
 	{ "tap", input_cmd_tap },
 	{ "tap_button_map", input_cmd_tap_button_map },
+	{ "xkb_file", input_cmd_xkb_file },
 	{ "xkb_layout", input_cmd_xkb_layout },
 	{ "xkb_model", input_cmd_xkb_model },
 	{ "xkb_options", input_cmd_xkb_options },
@@ -48,8 +49,8 @@ static struct cmd_handler input_config_handlers[] = {
 static void retranslate_keysyms(struct input_config *input_config) {
 	for (int i = 0; i < config->input_configs->length; ++i) {
 		struct input_config *ic = config->input_configs->items[i];
-		if (ic->xkb_layout) {
-			// this is the first config with xkb_layout
+		if (ic->xkb_layout || ic->xkb_file) {
+			// this is the first config with xkb_layout or xkb_file
 			if (ic->identifier == input_config->identifier) {
 				translate_keysyms(ic);
 			}

sway/commands/input/xkb_file.c

@@ -0,0 +1,26 @@
+#define _POSIX_C_SOURCE 200809L
+#include "sway/config.h"
+#include "sway/commands.h"
+#include "sway/input/input-manager.h"
+#include "log.h"
+
+struct cmd_results *input_cmd_xkb_file(int argc, char **argv) {
+	struct cmd_results *error = NULL;
+	if ((error = checkarg(argc, "xkb_file", EXPECTED_EQUAL_TO, 1))) {
+		return error;
+	}
+	struct input_config *ic = config->handler_context.input_config;
+	if (!ic) {
+		return cmd_results_new(CMD_FAILURE, "No input device defined.");
+	}
+
+	if (strcmp(argv[0], "-") == 0) {
+		ic->xkb_file = NULL;
+	} else {
+		ic->xkb_file = strdup(argv[0]);
+	}
+
+	sway_log(SWAY_DEBUG, "set-xkb_file for config: %s file: %s",
+			ic->identifier, ic->xkb_file);
+	return cmd_results_new(CMD_SUCCESS, NULL);
+}

sway/config/input.c

@@ -95,6 +95,10 @@ void merge_input_config(struct input_config *dst, struct input_config *src) {
 	if (src->tap_button_map != INT_MIN) {
 		dst->tap_button_map = src->tap_button_map;
 	}
+	if (src->xkb_file) {
+		free(dst->xkb_file);
+		dst->xkb_file = strdup(src->xkb_file);
+	}
 	if (src->xkb_layout) {
 		free(dst->xkb_layout);
 		dst->xkb_layout = strdup(src->xkb_layout);
@@ -307,6 +311,7 @@ void free_input_config(struct input_config *ic) {
 		return;
 	}
 	free(ic->identifier);
+	free(ic->xkb_file);
 	free(ic->xkb_layout);
 	free(ic->xkb_model);
 	free(ic->xkb_options);

sway/input/keyboard.c

@@ -534,20 +534,36 @@ static void handle_xkb_context_log(struct xkb_context *context,
 
 struct xkb_keymap *sway_keyboard_compile_keymap(struct input_config *ic,
 		char **error) {
-	struct xkb_rule_names rules = {0};
-	if (ic) {
-		input_config_fill_rule_names(ic, &rules);
-	}
-
 	struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
 	if (!sway_assert(context, "cannot create XKB context")) {
 		return NULL;
 	}
 	xkb_context_set_user_data(context, error);
 	xkb_context_set_log_fn(context, handle_xkb_context_log);
 
-	struct xkb_keymap *keymap =
-		xkb_keymap_new_from_names(context, &rules, XKB_KEYMAP_COMPILE_NO_FLAGS);
+	struct xkb_keymap *keymap = NULL;
+
+	if (ic && ic->xkb_file) {
+		FILE *keymap_file = fopen(ic->xkb_file, "r");
+		if (!keymap_file) {
+			sway_log_errno(SWAY_ERROR, "cannot open XKB file");
+		}
+
+		keymap = xkb_keymap_new_from_file(context, keymap_file,
+					XKB_KEYMAP_FORMAT_TEXT_V1, XKB_KEYMAP_COMPILE_NO_FLAGS);
+
+		if (!fclose(keymap_file)) {
+			sway_log_errno(SWAY_ERROR, "cannot close XKB file");
+		}
+	} else {
+		struct xkb_rule_names rules = {0};
+		if (ic) {
+			input_config_fill_rule_names(ic, &rules);
+		}
+		keymap = xkb_keymap_new_from_names(context, &rules,
+			XKB_KEYMAP_COMPILE_NO_FLAGS);
+	}
+
 	xkb_context_set_user_data(context, NULL);
 	xkb_context_unref(context);
 	return keymap;

sway/meson.build

@@ -160,6 +160,7 @@ sway_sources = files(
 	'commands/input/tap.c',
 	'commands/input/tap_button_map.c',
 	'commands/input/xkb_capslock.c',
+	'commands/input/xkb_file.c',
 	'commands/input/xkb_layout.c',
 	'commands/input/xkb_model.c',
 	'commands/input/xkb_numlock.c',

sway/sway-input.5.scd

@@ -44,6 +44,11 @@ on top of the existing device configurations.
 For more information on these xkb configuration options, see
 *xkeyboard-config*(7).
 
+*input* <identifier> xkb_file <file_name>
+	Sets all xkb configurations from a complete .xkb file. This file can be
+	dumped from _xkbcomp $DISPLAY keymap.xkb_. This setting overrides
+	xkb_layout, xkb_model, xkb_options, xkb_rules, and xkb_variant settings.
+
 *input* <identifier> xkb_layout <layout_name>
 	Sets the layout of the keyboard like _us_ or _de_.