Send unique keymap file descriptors

To prevent wl_keyboard keymap being written to by clients, use a unique
file descriptor for each wl_keyboard resource.

Reference: weston, commit 76829fc4eaea329d2a525c3978271e13bd76c078

include/wlr/types/wlr_keyboard.h

@@ -50,7 +50,7 @@ struct wlr_keyboard_modifiers {
 struct wlr_keyboard {
 	const struct wlr_keyboard_impl *impl;
 
-	int keymap_fd;
+	char *keymap_string;
 	size_t keymap_size;
 	struct xkb_keymap *keymap;
 	struct xkb_state *xkb_state;

types/seat/wlr_seat_keyboard.c

@@ -3,6 +3,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <sys/mman.h>
+#include <unistd.h>
 #include <wayland-server.h>
 #include <wlr/types/wlr_data_device.h>
 #include <wlr/types/wlr_input_device.h>
@@ -10,6 +12,7 @@
 #include <wlr/util/log.h>
 #include "types/wlr_seat.h"
 #include "util/signal.h"
+#include "util/os-compatibility.h"
 
 static void default_keyboard_enter(struct wlr_seat_keyboard_grab *grab,
 		struct wlr_surface *surface, uint32_t keycodes[], size_t num_keycodes,
@@ -338,9 +341,28 @@ static void seat_client_send_keymap(struct wlr_seat_client *client,
 			continue;
 		}
 
+		int keymap_fd = os_create_anonymous_file(keyboard->keymap_size);
+		if (keymap_fd < 0) {
+			wlr_log(WLR_ERROR, "creating a keymap file for %zu bytes failed", keyboard->keymap_size);
+			continue;
+		}
+
+		void *ptr = mmap(NULL, keyboard->keymap_size, PROT_READ | PROT_WRITE,
+				MAP_SHARED, keymap_fd, 0);
+		if (ptr == MAP_FAILED) {
+			wlr_log(WLR_ERROR, "failed to mmap() %zu bytes", keyboard->keymap_size);
+			close(keymap_fd);
+			continue;
+		}
+
+		strcpy(ptr, keyboard->keymap_string);
+		munmap(ptr, keyboard->keymap_size);
+
 		wl_keyboard_send_keymap(resource,
-			WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1, keyboard->keymap_fd,
+			WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1, keymap_fd,
 			keyboard->keymap_size);
+
+		close(keymap_fd);
 	}
 }
 

types/wlr_keyboard.c

@@ -2,16 +2,12 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
-#include <sys/mman.h>
-#include <unistd.h>
 #include <wayland-server.h>
 #include <wlr/interfaces/wlr_keyboard.h>
 #include <wlr/types/wlr_keyboard.h>
 #include <wlr/util/log.h>
 #include "util/signal.h"
 
-int os_create_anonymous_file(off_t size);
-
 static void keyboard_led_update(struct wlr_keyboard *keyboard) {
 	if (keyboard->xkb_state == NULL) {
 		return;
@@ -126,7 +122,6 @@ void wlr_keyboard_init(struct wlr_keyboard *kb,
 	wl_signal_init(&kb->events.modifiers);
 	wl_signal_init(&kb->events.keymap);
 	wl_signal_init(&kb->events.repeat_info);
-	kb->keymap_fd = -1;
 
 	// Sane defaults
 	kb->repeat_info.rate = 25;
@@ -139,9 +134,7 @@ void wlr_keyboard_destroy(struct wlr_keyboard *kb) {
 	}
 	xkb_state_unref(kb->xkb_state);
 	xkb_keymap_unref(kb->keymap);
-	if (kb->keymap_fd >= 0) {
-		close(kb->keymap_fd);
-	}
+	free(kb->keymap_string);
 	if (kb->impl && kb->impl->destroy) {
 		kb->impl->destroy(kb);
 	} else {
@@ -158,8 +151,6 @@ void wlr_keyboard_led_update(struct wlr_keyboard *kb, uint32_t leds) {
 
 void wlr_keyboard_set_keymap(struct wlr_keyboard *kb,
 		struct xkb_keymap *keymap) {
-	char *keymap_str = NULL;
-
 	xkb_keymap_unref(kb->keymap);
 	kb->keymap = xkb_keymap_ref(keymap);
 
@@ -194,26 +185,15 @@ void wlr_keyboard_set_keymap(struct wlr_keyboard *kb,
 		kb->mod_indexes[i] = xkb_map_mod_get_index(kb->keymap, mod_names[i]);
 	}
 
-	keymap_str = xkb_keymap_get_as_string(kb->keymap,
+	char *tmp_keymap_string = xkb_keymap_get_as_string(kb->keymap,
 		XKB_KEYMAP_FORMAT_TEXT_V1);
-	kb->keymap_size = strlen(keymap_str) + 1;
-	if (kb->keymap_fd >= 0) {
-		close(kb->keymap_fd);
-	}
-	kb->keymap_fd = os_create_anonymous_file(kb->keymap_size);
-	if (kb->keymap_fd < 0) {
-		wlr_log(WLR_ERROR, "creating a keymap file for %zu bytes failed", kb->keymap_size);
+	if (tmp_keymap_string == NULL) {
+		wlr_log(WLR_ERROR, "Failed to get string version of keymap");
 		goto err;
 	}
-	void *ptr = mmap(NULL, kb->keymap_size,
-		PROT_READ | PROT_WRITE, MAP_SHARED, kb->keymap_fd, 0);
-	if (ptr == (void*)-1) {
-		wlr_log(WLR_ERROR, "failed to mmap() %zu bytes", kb->keymap_size);
-		goto err;
-	}
-	strcpy(ptr, keymap_str);
-	free(keymap_str);
-	munmap(ptr, kb->keymap_size);
+	free(kb->keymap_string);
+	kb->keymap_string = tmp_keymap_string;
+	kb->keymap_size = strlen(kb->keymap_string) + 1;
 
 	for (size_t i = 0; i < kb->num_keycodes; ++i) {
 		xkb_keycode_t keycode = kb->keycodes[i] + 8;
@@ -230,11 +210,8 @@ err:
 	kb->xkb_state = NULL;
 	xkb_keymap_unref(keymap);
 	kb->keymap = NULL;
-	if (kb->keymap_fd >= 0) {
-		close(kb->keymap_fd);
-		kb->keymap_fd = -1;
-	}
-	free(keymap_str);
+	free(kb->keymap_string);
+	kb->keymap_string = NULL;
 }
 
 void wlr_keyboard_set_repeat_info(struct wlr_keyboard *kb, int32_t rate,