Handle empty as full empty and fix discarding of previous results

loc.go

@@ -36,8 +36,8 @@ func (i *iface) ProcLoc() (err error) {
 	}
 
 	var (
-		pci, usb string
-		procmode int
+		pci, usb, tmp string
+		procmode      int
 	)
 	for _, v := range strings.Split(devpath, "/") {
 		if strings.HasPrefix(v, "pci") {
@@ -51,18 +51,23 @@ func (i *iface) ProcLoc() (err error) {
 		switch procmode {
 		case PathProcPCI:
 			{
-				if pci, err = i.ProcPCI(v); err != nil {
+				if tmp, err = i.ProcPCI(v); err != nil {
 					continue
 				}
+				pci = tmp
 			}
 		case PathProcUSB:
 			{
-				if usb, err = i.ProcUSB(v); err != nil {
+				if tmp, err = i.ProcUSB(v); err != nil {
 					continue
 				}
+				usb = tmp
 			}
 		}
 	}
+	if pci == "" && usb == "" {
+		return
+	}
 	i.names[IfNameLoc] = strings.Join([]string{i.pfx, pci, usb}, "")
 
 	return