Function unp_externalize

freebsd/kern/uipc_usrreq.c:2002–2112

}

static int
unp_externalize(struct mbuf *control, struct mbuf **controlp, int flags)
{
	struct thread *td = curthread;		/* XXX */
	struct cmsghdr *cm = mtod(control, struct cmsghdr *);
	int i;
	int *fdp;
	struct filedesc *fdesc = td->td_proc->p_fd;
	struct filedescent **fdep;
	void *data;
	socklen_t clen = control->m_len, datalen;
	int error, newfds;
	u_int newlen;

	UNP_LINK_UNLOCK_ASSERT();

	error = 0;
	if (controlp != NULL) /* controlp == NULL => free control messages */
		*controlp = NULL;
	while (cm != NULL) {
		if (sizeof(*cm) > clen || cm->cmsg_len > clen) {
			error = EINVAL;
			break;
		}
		data = CMSG_DATA(cm);
		datalen = (caddr_t)cm + cm->cmsg_len - (caddr_t)data;
		if (cm->cmsg_level == SOL_SOCKET
		    && cm->cmsg_type == SCM_RIGHTS) {
			newfds = datalen / sizeof(*fdep);
			if (newfds == 0)
				goto next;
			fdep = data;

			/* If we're not outputting the descriptors free them. */
			if (error || controlp == NULL) {
				unp_freerights(fdep, newfds);
				goto next;
			}
			FILEDESC_XLOCK(fdesc);

			/*
			 * Now change each pointer to an fd in the global
			 * table to an integer that is the index to the local
			 * fd table entry that we set up to point to the
			 * global one we are transferring.
			 */
			newlen = newfds * sizeof(int);
			*controlp = sbcreatecontrol(NULL, newlen,
			    SCM_RIGHTS, SOL_SOCKET);
			if (*controlp == NULL) {
				FILEDESC_XUNLOCK(fdesc);
				error = E2BIG;
				unp_freerights(fdep, newfds);
				goto next;
			}

			fdp = (int *)
			    CMSG_DATA(mtod(*controlp, struct cmsghdr *));