Function create_device_info_with_usage

lib/hidapi/mac/hid.c:540–651

}

static struct hid_device_info *create_device_info_with_usage(IOHIDDeviceRef dev, int32_t usage_page, int32_t usage)
{
	unsigned short dev_vid;
	unsigned short dev_pid;
	int BUF_LEN = 256;
	wchar_t buf[BUF_LEN];
	CFTypeRef transport_prop;

	struct hid_device_info *cur_dev;
	io_service_t hid_service;
	kern_return_t res;
	uint64_t entry_id = 0;

	if (dev == NULL) {
		return NULL;
	}

	cur_dev = (struct hid_device_info *)calloc(1, sizeof(struct hid_device_info));
	if (cur_dev == NULL) {
		return NULL;
	}

	dev_vid = get_vendor_id(dev);
	dev_pid = get_product_id(dev);

	cur_dev->usage_page = usage_page;
	cur_dev->usage = usage;

	/* Fill out the record */
	cur_dev->next = NULL;

	/* Fill in the path (as a unique ID of the service entry) */
	cur_dev->path = NULL;
	hid_service = IOHIDDeviceGetService(dev);
	if (hid_service != MACH_PORT_NULL) {
		res = IORegistryEntryGetRegistryEntryID(hid_service, &entry_id);
	}
	else {
		res = KERN_INVALID_ARGUMENT;
	}

	if (res == KERN_SUCCESS) {
		/* max value of entry_id(uint64_t) is 18446744073709551615 which is 20 characters long,
		   so for (max) "path" string 'DevSrvsID:18446744073709551615' we would need
		   9+1+20+1=31 bytes buffer, but allocate 32 for simple alignment */
		const size_t path_len = 32;
		cur_dev->path = calloc(1, path_len);
		if (cur_dev->path != NULL) {
			snprintf(cur_dev->path, path_len, "DevSrvsID:%llu", entry_id);
		}
	}

	if (cur_dev->path == NULL) {
		/* for whatever reason, trying to keep it a non-NULL string */
		cur_dev->path = strdup("");
	}

	/* Serial Number */