/* USB::DevHandle#usb_get_descriptor(type, index, buf) */
static VALUE
rusb_get_descriptor(
  VALUE v,
  VALUE vtype,
  VALUE vindex,
  VALUE vbuf)
{
  usb_dev_handle *p = get_usb_devhandle(v);
  int type = NUM2INT(vtype);
  int index = NUM2INT(vindex);
  char *buf;
  int buflen;
  int ret;
  StringValue(vbuf);
  rb_str_modify(vbuf);
  buf = RSTRING_PTR(vbuf);
  buflen = RSTRING_LEN(vbuf);
  ret = usb_get_descriptor(p, type, index, buf, buflen);
  check_usb_error("usb_get_descriptor", ret);
  return INT2NUM(ret);
}