gctl_get_param_flags
void *gctl_get_param_flags(struct gctl_req *req, const char *param, int flags, int *len);
return (gctl_get_param_flags(req, param, GCTL_PARAM_RD, len));
p = gctl_get_param_flags(req, param, GCTL_PARAM_RD, &len);
buf = gctl_get_param_flags(req, "output", GCTL_PARAM_WR, &len);