Function uprintf

freebsd/kern/subr_prf.c:169–215

* Uprintf prints to the controlling terminal for the current process. */

 * Uprintf prints to the controlling terminal for the current process.
 */
int
uprintf(const char *fmt, ...)
{
	va_list ap;
	struct putchar_arg pca;
	struct proc *p;
	struct thread *td;
	int retval;

	td = curthread;
	if (TD_IS_IDLETHREAD(td))
		return (0);

	if (td->td_proc == initproc) {
		/* Produce output when we fail to load /sbin/init: */
		va_start(ap, fmt);
		retval = vprintf(fmt, ap);
		va_end(ap);
		return (retval);
	}

	sx_slock(&proctree_lock);
	p = td->td_proc;
	PROC_LOCK(p);
	if ((p->p_flag & P_CONTROLT) == 0) {
		PROC_UNLOCK(p);
		sx_sunlock(&proctree_lock);
		return (0);
	}
	SESS_LOCK(p->p_session);
	pca.tty = p->p_session->s_ttyp;
	SESS_UNLOCK(p->p_session);
	PROC_UNLOCK(p);
	if (pca.tty == NULL) {
		sx_sunlock(&proctree_lock);
		return (0);
	}
	pca.flags = TOTTY;
	pca.p_bufr = NULL;
	va_start(ap, fmt);
	tty_lock(pca.tty);
	sx_sunlock(&proctree_lock);
	retval = kvprintf(fmt, putchar, &pca, 10, ap);
	tty_unlock(pca.tty);
	va_end(ap);
	return (retval);
}

/*
 * tprintf and vtprintf print on the controlling terminal associated with the