Function fsetown

freebsd/kern/kern_descrip.c:1143–1229

* This is common code for FIOSETOWN ioctl called by fcntl(fd, F_SETOWN, arg). * * After permission checking, add a sigio structure to the sigio list for * the process or process group. */

 * the process or process group.
 */
int
fsetown(pid_t pgid, struct sigio **sigiop)
{
	struct proc *proc;
	struct pgrp *pgrp;
	struct sigio *osigio, *sigio;
	int ret;

	if (pgid == 0) {
		funsetown(sigiop);
		return (0);
	}

	ret = 0;

	sigio = malloc(sizeof(struct sigio), M_SIGIO, M_WAITOK);
	sigio->sio_pgid = pgid;
	sigio->sio_ucred = crhold(curthread->td_ucred);
	sigio->sio_myref = sigiop;

	sx_slock(&proctree_lock);
	SIGIO_LOCK();
	osigio = funsetown_locked(*sigiop);
	if (pgid > 0) {
		proc = pfind(pgid);
		if (proc == NULL) {
			ret = ESRCH;
			goto fail;
		}

		/*
		 * Policy - Don't allow a process to FSETOWN a process
		 * in another session.
		 *
		 * Remove this test to allow maximum flexibility or
		 * restrict FSETOWN to the current process or process
		 * group for maximum safety.
		 */
		if (proc->p_session != curthread->td_proc->p_session) {
			PROC_UNLOCK(proc);
			ret = EPERM;
			goto fail;
		}

		sigio->sio_proc = proc;
		SLIST_INSERT_HEAD(&proc->p_sigiolst, sigio, sio_pgsigio);
		PROC_UNLOCK(proc);
	} else /* if (pgid < 0) */ {
		pgrp = pgfind(-pgid);
		if (pgrp == NULL) {
			ret = ESRCH;
			goto fail;
		}

		/*
		 * Policy - Don't allow a process to FSETOWN a process
		 * in another session.
		 *