jailparam_set
jid = jailparam_set(jp, njp, flags);
extern int jailparam_set(struct jailparam *jp, unsigned njp, int flags);
jid = jailparam_set(params, params_count, flags);
if (jailparam_set(params, i, JAIL_UPDATE) < 0)
jid = jailparam_set(jp, njp, flags);