Function pdinit

freebsd/kern/kern_descrip.c:2173–2197

* Build a pwddesc structure from another. * Copy the current, root, and jail root vnode references. * * If pdp is not NULL, return with it shared locked. */

 * If pdp is not NULL, return with it shared locked.
 */
struct pwddesc *
pdinit(struct pwddesc *pdp, bool keeplock)
{
	struct pwddesc *newpdp;
	struct pwd *newpwd;

	newpdp = malloc(sizeof(*newpdp), M_PWDDESC, M_WAITOK | M_ZERO);

	PWDDESC_LOCK_INIT(newpdp);
	refcount_init(&newpdp->pd_refcount, 1);
	newpdp->pd_cmask = CMASK;

	if (pdp == NULL) {
		newpwd = pwd_alloc();
		smr_serialized_store(&newpdp->pd_pwd, newpwd, true);
		return (newpdp);
	}

	PWDDESC_XLOCK(pdp);
	newpwd = pwd_hold_pwddesc(pdp);
	smr_serialized_store(&newpdp->pd_pwd, newpwd, true);
	if (!keeplock)
		PWDDESC_XUNLOCK(pdp);
	return (newpdp);
}

static struct filedesc *
fdhold(struct proc *p)