Adventures In ioctl(2) Support
Explanations

struct explain_iocontrol_t
{
    const char *name;
    int number;
    int (*disambiguate)(int fildes, int request, const void *data);
    void (*print_data)(int fildes, int request, const void *data);
    void (*print_explanation)(int fildes, int request, const void *data);
    etc
};