|int(*||match_function )(USBDevice_t *device, void *privdata)|
|struct USBDeviceMatcher_s *||next|
USBDeviceMatcher_t: A "USB matcher" is a callback function that inputs a USBDevice_t structure, and returns 1 for a match and 0 for a non-match. Thus, a matcher provides a criterion for selecting a USB device. The callback function further is expected to return -1 on error with errno set, and -2 on other errors. Matchers can be connected in a linked list via the "next" field.