interface/wlr_touch: rework destroy sequence

The destroy callback in wlr_touch_impl has been removed. The function
`wlr_touch_finish` has been introduced to clean up the resources owned by a
wlr_touch.

`wlr_input_device_destroy` no longer destroys the wlr_touch, attempting to
destroy a wlr_touch will result in a no-op.

The field `name` has been added to the wlr_touch_impl to be able to identify
a given wlr_touch device.

backend/libinput/events.c

@@ -24,7 +24,7 @@ void destroy_libinput_input_device(struct wlr_libinput_input_device *dev) {
 		wlr_switch_finish(&dev->switch_device);
 	}
 	if (dev->touch.impl) {
-		wlr_touch_destroy(&dev->touch);
+		wlr_touch_finish(&dev->touch);
 	}
 	if (dev->tablet.impl) {
 		finish_device_tablet(dev);

backend/libinput/touch.c

@@ -4,12 +4,8 @@
 #include "backend/libinput.h"
 #include "util/signal.h"
 
-static void touch_destroy(struct wlr_touch *touch) {
-	/* wlr_touch belongs to the wlr_libinput_input_device */
-}
-
 const struct wlr_touch_impl libinput_touch_impl = {
-	.destroy = touch_destroy,
+	.name = "libinput-touch",
 };
 
 void init_device_touch(struct wlr_libinput_input_device *dev) {

backend/wayland/seat.c

@@ -567,6 +567,10 @@ void destroy_wl_input_device(struct wlr_wl_input_device *dev) {
 			wlr_tablet_finish(wlr_dev->tablet);
 			free(wlr_dev->tablet);
 			break;
+		case WLR_INPUT_DEVICE_TOUCH:
+			wlr_touch_finish(wlr_dev->touch);
+			free(wlr_dev->touch);
+			break;
 		default:
 			wlr_input_device_destroy(wlr_dev);
 			break;

backend/x11/input_device.c

@@ -293,12 +293,8 @@ const struct wlr_pointer_impl x11_pointer_impl = {
 	.name = "x11-pointer",
 };
 
-static void touch_destroy(struct wlr_touch *wlr_touch) {
-	// Don't free the touch, it's on the stack
-}
-
 const struct wlr_touch_impl x11_touch_impl = {
-	.destroy = touch_destroy,
+	.name = "x11-touch",
 };
 
 void update_x11_pointer_position(struct wlr_x11_output *output,

backend/x11/output.c

@@ -77,7 +77,7 @@ static void output_destroy(struct wlr_output *wlr_output) {
 	pixman_region32_fini(&output->exposed);
 
 	wlr_pointer_finish(&output->pointer);
-	wlr_touch_destroy(&output->touch);
+	wlr_touch_finish(&output->touch);
 
 	struct wlr_x11_buffer *buffer, *buffer_tmp;
 	wl_list_for_each_safe(buffer, buffer_tmp, &output->buffers, link) {

include/wlr/interfaces/wlr_touch.h

@@ -12,11 +12,11 @@
 #include <wlr/types/wlr_touch.h>
 
 struct wlr_touch_impl {
-	void (*destroy)(struct wlr_touch *touch);
+	const char *name;
 };
 
 void wlr_touch_init(struct wlr_touch *touch,
 	const struct wlr_touch_impl *impl, const char *name);
-void wlr_touch_destroy(struct wlr_touch *touch);
+void wlr_touch_finish(struct wlr_touch *touch);
 
 #endif

types/wlr_input_device.c

@@ -2,7 +2,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <wayland-server-core.h>
-#include <wlr/interfaces/wlr_touch.h>
 #include <wlr/types/wlr_input_device.h>
 #include <wlr/util/log.h>
 #include "util/signal.h"
@@ -45,7 +44,7 @@ void wlr_input_device_destroy(struct wlr_input_device *dev) {
 			wlr_log(WLR_ERROR, "wlr_switch will not be destroyed");
 			break;
 		case WLR_INPUT_DEVICE_TOUCH:
-			wlr_touch_destroy(dev->touch);
+			wlr_log(WLR_ERROR, "wlr_touch will not be destroyed");
 			break;
 		case WLR_INPUT_DEVICE_TABLET_TOOL:
 			wlr_log(WLR_ERROR, "wlr_tablet_tool will not be destroyed");

types/wlr_touch.c

@@ -17,11 +17,6 @@ void wlr_touch_init(struct wlr_touch *touch,
 	wl_signal_init(&touch->events.frame);
 }
 
-void wlr_touch_destroy(struct wlr_touch *touch) {
+void wlr_touch_finish(struct wlr_touch *touch) {
 	wlr_input_device_finish(&touch->base);
-	if (touch && touch->impl && touch->impl->destroy) {
-		touch->impl->destroy(touch);
-	} else {
-		free(touch);
-	}
 }