Function pwd_chroot

freebsd/kern/kern_descrip.c:3899–3940

* The caller is responsible for invoking priv_check() and * mac_vnode_check_chroot() to authorize this operation. */

* mac_vnode_check_chroot() to authorize this operation.
*/
int
pwd_chroot(struct thread *td, struct vnode *vp)
{
	struct pwddesc *pdp;
	struct filedesc *fdp;
	struct pwd *newpwd, *oldpwd;
	int error;

	fdp = td->td_proc->p_fd;
	pdp = td->td_proc->p_pd;
	newpwd = pwd_alloc();
	FILEDESC_SLOCK(fdp);
	PWDDESC_XLOCK(pdp);
	#pragma GCC diagnostic ignored "-Wcast-qual"
	oldpwd = PWDDESC_XLOCKED_LOAD_PWD(pdp);
	#pragma GCC diagnostic error "-Wcast-qual"
	if (chroot_allow_open_directories == 0 ||
	    (chroot_allow_open_directories == 1 &&
	    oldpwd->pwd_rdir != rootvnode)) {
		error = chroot_refuse_vdir_fds(fdp);
		FILEDESC_SUNLOCK(fdp);
		if (error != 0) {
			PWDDESC_XUNLOCK(pdp);
			pwd_drop(newpwd);
			return (error);
		}
	} else {
		FILEDESC_SUNLOCK(fdp);
	}

	vrefact(vp);
	newpwd->pwd_rdir = vp;
	if (oldpwd->pwd_jdir == NULL) {
		vrefact(vp);
		newpwd->pwd_jdir = vp;
	}
	pwd_fill(oldpwd, newpwd);
	pwd_set(pdp, newpwd);
	PWDDESC_XUNLOCK(pdp);
	pwd_drop(oldpwd);
	return (0);
}

void
pwd_chdir(struct thread *td, struct vnode *vp)