input: use ro_anonymous_file to minimize duplication of keymap files

Since version 7 clients must use MAP_PRIVATE to map the keymap fd so we
can use memfd_create in os_ro_anonymous_file_get_ref using
RO_ANONYMOUS_FILE_MAPMODE_PRIVATE, for older version we use
RO_ANONYMOUS_FILE_MAPMODE_SHARED to be compatibile with MAP_SHARED.

Signed-off-by: Sebastian Wick <sebastian@sebastianwick.net>

include/libweston/libweston.h

@@ -78,6 +78,7 @@ struct weston_pointer;
 struct linux_dmabuf_buffer;
 struct weston_recorder;
 struct weston_pointer_constraint;
+struct ro_anonymous_file;
 
 enum weston_keyboard_modifier {
 	MODIFIER_CTRL = (1 << 0),
@@ -704,8 +705,7 @@ weston_pointer_start_drag(struct weston_pointer *pointer,
 		       struct wl_client *client);
 struct weston_xkb_info {
 	struct xkb_keymap *keymap;
-	size_t keymap_size;
-	char *keymap_string;
+	struct ro_anonymous_file *keymap_rofile;
 	int32_t ref_count;
 	xkb_mod_index_t shift_mod;
 	xkb_mod_index_t caps_mod;

libweston/input.c

@@ -2086,32 +2086,30 @@ WL_EXPORT void
 weston_keyboard_send_keymap(struct weston_keyboard *kbd, struct wl_resource *resource)
 {
 	struct weston_xkb_info *xkb_info = kbd->xkb_info;
-	void *area;
 	int fd;
+	size_t size;
+	enum ro_anonymous_file_mapmode mapmode;
 
-	fd = os_create_anonymous_file(xkb_info->keymap_size);
-	if (fd < 0) {
-		weston_log("creating a keymap file for %lu bytes failed: %s\n",
-			   (unsigned long) xkb_info->keymap_size,
+	if (wl_resource_get_version(resource) < 7)
+		mapmode = RO_ANONYMOUS_FILE_MAPMODE_SHARED;
+	else
+		mapmode = RO_ANONYMOUS_FILE_MAPMODE_PRIVATE;
+
+	fd = os_ro_anonymous_file_get_fd(xkb_info->keymap_rofile, mapmode);
+	size = os_ro_anonymous_file_size(xkb_info->keymap_rofile);
+
+	if (fd == -1) {
+		weston_log("creating a keymap file failed: %s\n",
 			   strerror(errno));
 		return;
 	}
 
-	area = mmap(NULL, xkb_info->keymap_size, PROT_READ | PROT_WRITE,
-		    MAP_SHARED, fd, 0);
-	if (area == MAP_FAILED) {
-		weston_log("failed to mmap() %lu bytes\n",
-			   (unsigned long) xkb_info->keymap_size);
-		goto err_mmap;
-	}
-	strcpy(area, xkb_info->keymap_string);
-	munmap(area, xkb_info->keymap_size);
 	wl_keyboard_send_keymap(resource,
 				WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1,
 				fd,
-				xkb_info->keymap_size);
-err_mmap:
-	close(fd);
+				size);
+
+	os_ro_anonymous_file_put_fd(fd);
 }
 
 static void
@@ -3149,8 +3147,7 @@ weston_xkb_info_destroy(struct weston_xkb_info *xkb_info)
 
 	xkb_keymap_unref(xkb_info->keymap);
 
-	if (xkb_info->keymap_string)
-		free(xkb_info->keymap_string);
+	os_ro_anonymous_file_destroy(xkb_info->keymap_rofile);
 	free(xkb_info);
 }
 
@@ -3171,6 +3168,8 @@ weston_compositor_xkb_destroy(struct weston_compositor *ec)
 static struct weston_xkb_info *
 weston_xkb_info_create(struct xkb_keymap *keymap)
 {
+	char *keymap_string;
+	size_t keymap_size;
 	struct weston_xkb_info *xkb_info = zalloc(sizeof *xkb_info);
 	if (xkb_info == NULL)
 		return NULL;
@@ -3202,13 +3201,22 @@ weston_xkb_info_create(struct xkb_keymap *keymap)
 	xkb_info->scroll_led = xkb_keymap_led_get_index(xkb_info->keymap,
 							XKB_LED_NAME_SCROLL);
 
-	xkb_info->keymap_string = xkb_keymap_get_as_string(xkb_info->keymap,
+	keymap_string = xkb_keymap_get_as_string(xkb_info->keymap,
 							   XKB_KEYMAP_FORMAT_TEXT_V1);
-	if (xkb_info->keymap_string == NULL) {
+	if (keymap_string == NULL) {
 		weston_log("failed to get string version of keymap\n");
 		goto err_keymap;
 	}
-	xkb_info->keymap_size = strlen(xkb_info->keymap_string) + 1;
+	keymap_size = strlen(keymap_string) + 1;
+
+	xkb_info->keymap_rofile = os_ro_anonymous_file_create(keymap_size,
+							      keymap_string);
+	free(keymap_string);
+
+	if (!xkb_info->keymap_rofile) {
+		weston_log("failed to create anonymous file for keymap\n");
+		goto err_keymap;
+	}
 
 	return xkb_info;
 
@@ -3441,7 +3449,8 @@ weston_seat_init(struct weston_seat *seat, struct weston_compositor *ec,
 	wl_signal_init(&seat->destroy_signal);
 	wl_signal_init(&seat->updated_caps_signal);
 
-	seat->global = wl_global_create(ec->wl_display, &wl_seat_interface, 7,
+	seat->global = wl_global_create(ec->wl_display, &wl_seat_interface,
+					MIN(wl_seat_interface.version, 7),
 					seat, bind_seat);
 
 	seat->compositor = ec;