input-device: add output_name field, populate it from libinput

backend/libinput/events.c

@@ -1,3 +1,4 @@
+#define _POSIX_C_SOURCE 200809L
 #include <assert.h>
 #include <libinput.h>
 #include <stdlib.h>
@@ -48,6 +49,10 @@ static struct wlr_input_device *allocate_device(
 	struct wlr_input_device *wlr_dev = &wlr_libinput_dev->wlr_input_device;
 	libinput_device_get_size(libinput_dev,
 			&wlr_dev->width_mm, &wlr_dev->height_mm);
+	const char *output_name = libinput_device_get_output_name(libinput_dev);
+	if (output_name != NULL) {
+		wlr_dev->output_name = strdup(output_name);
+	}
 	wl_list_insert(wlr_devices, &wlr_dev->link);
 	wlr_libinput_dev->handle = libinput_dev;
 	libinput_device_ref(libinput_dev);

include/wlr/types/wlr_input_device.h

@@ -11,7 +11,7 @@ enum wlr_input_device_type {
 	WLR_INPUT_DEVICE_POINTER,
 	WLR_INPUT_DEVICE_TOUCH,
 	WLR_INPUT_DEVICE_TABLET_TOOL,
-	WLR_INPUT_DEVICE_TABLET_PAD
+	WLR_INPUT_DEVICE_TABLET_PAD,
 };
 
 /* Note: these are circular dependencies */
@@ -27,10 +27,11 @@ struct wlr_input_device {
 	const struct wlr_input_device_impl *impl;
 
 	enum wlr_input_device_type type;
-	int vendor, product;
+	unsigned int vendor, product;
 	char *name;
 	// Or 0 if not applicable to this device
 	double width_mm, height_mm;
+	char *output_name;
 
 	/* wlr_input_device.type determines which of these is valid */
 	union {

types/wlr_input_device.c

@@ -56,6 +56,7 @@ void wlr_input_device_destroy(struct wlr_input_device *dev) {
 		}
 	}
 	free(dev->name);
+	free(dev->output_name);
 	if (dev->impl && dev->impl->destroy) {
 		dev->impl->destroy(dev);
 	} else {