Function epair_clone_create

freebsd/net/if_epair.c:730–916

}

static int
epair_clone_create(struct if_clone *ifc, char *name, size_t len, caddr_t params)
{
	struct epair_softc *sca, *scb;
	struct ifnet *ifp;
	char *dp;
	int error, unit, wildcard;
	uint64_t hostid;
	uint32_t key[3];
	uint32_t hash;
	uint8_t eaddr[ETHER_ADDR_LEN];	/* 00:00:00:00:00:00 */

	/* Try to see if a special unit was requested. */
	error = ifc_name2unit(name, &unit);
	if (error != 0)
		return (error);
	wildcard = (unit < 0);

	error = ifc_alloc_unit(ifc, &unit);
	if (error != 0)
		return (error);

	/*
	 * If no unit had been given, we need to adjust the ifName.
	 * Also make sure there is space for our extra [ab] suffix.
	 */
	for (dp = name; *dp != '\0'; dp++);
	if (wildcard) {
		error = snprintf(dp, len - (dp - name), "%d", unit);
		if (error > len - (dp - name) - 1) {
			/* ifName too long. */
			ifc_free_unit(ifc, unit);
			return (ENOSPC);
		}
		dp += error;
	}
	if (len - (dp - name) - 1 < 1) {
		/* No space left for our [ab] suffix. */
		ifc_free_unit(ifc, unit);
		return (ENOSPC);
	}
	*dp = 'b';
	/* Must not change dp so we can replace 'a' by 'b' later. */
	*(dp+1) = '\0';

	/* Check if 'a' and 'b' interfaces already exist. */ 
	if (ifunit(name) != NULL)
		return (EEXIST);
	*dp = 'a';
	if (ifunit(name) != NULL)
		return (EEXIST);

	/* Allocate memory for both [ab] interfaces */
	sca = malloc(sizeof(struct epair_softc), M_EPAIR, M_WAITOK | M_ZERO);
	EPAIR_REFCOUNT_INIT(&sca->refcount, 1);
	sca->ifp = if_alloc(IFT_ETHER);
	if (sca->ifp == NULL) {
		free(sca, M_EPAIR);