rbd: refactor GetImageNames to use a for loop instead of recursion

This is done because using a for loop is more idiomatic in Go code.

Signed-off-by: Sanford Miller <smiller@digitalocean.com>

rbd/rbd_nautilus.go

@@ -19,11 +19,23 @@ import (
 
 // GetImageNames returns the list of current RBD images.
 func GetImageNames(ioctx *rados.IOContext) ([]string, error) {
+	var images []C.rbd_image_spec_t
 	size := C.size_t(4096)
-	images, err := getImageNames(ioctx, &size)
+	for {
+		images = make([]C.rbd_image_spec_t, size)
+		ret := C.rbd_list2(
+			cephIoctx(ioctx),
+			(*C.rbd_image_spec_t)(unsafe.Pointer(&images[0])),
+			&size)
+		err := getErrorIfNegative(ret)
 		if err != nil {
+			if err == errRange {
+				continue
+			}
 			return nil, err
 		}
+		break
+	}
 	defer C.rbd_image_spec_list_cleanup((*C.rbd_image_spec_t)(unsafe.Pointer(&images[0])), size)
 
 	names := make([]string, size)
@@ -33,22 +45,6 @@ func GetImageNames(ioctx *rados.IOContext) ([]string, error) {
 	return names, nil
 }
 
-func getImageNames(ioctx *rados.IOContext, size *C.size_t) ([]C.rbd_image_spec_t, error) {
-	images := make([]C.rbd_image_spec_t, *size)
-	ret := C.rbd_list2(
-		cephIoctx(ioctx),
-		(*C.rbd_image_spec_t)(unsafe.Pointer(&images[0])),
-		size)
-	err := getErrorIfNegative(ret)
-	if err != nil {
-		if err == errRange {
-			return getImageNames(ioctx, size)
-		}
-		return nil, err
-	}
-	return images, nil
-}
-
 // GetCreateTimestamp returns the time the rbd image was created.
 //
 // Implements: