* returned data is not NULL.
*
* Return the size of the received data on success or else a negative lttng
* error code. If buf is NULL, 0 is returned on success.
*/
int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,
* returned data is not NULL.
*
* Return the size of the received data on success or else a negative lttng
* error code. If buf is NULL, 0 is returned on success.
*/
int lttng_ctl_ask_sessiond_varlen(struct lttcomm_session_msg *lsm,