vsscanf
int vsscanf(const char * __restrict, const char * __restrict, __va_list)
ret = vsscanf(str, fmt, ap);
ns = vsscanf(val, fmt, ap);
ret = vsscanf(ibuf, fmt, ap);
ret = vsscanf(opt->value, fmt, ap);
int vsscanf(const char * _Nonnull, char const * _Nonnull, __va_list) __scanflike(2, 0);