Clean segregated file share backends

share/backend.go

@@ -0,0 +1,19 @@
+package share
+
+import "context"
+
+type NewBackendFunc func(uc *UserConfiguration) (Backend, *VMShareOptions, error)
+
+type Backend interface {
+	Apply(ctx context.Context, sharePWD string, vc *VMShareContext) (string, error)
+}
+
+var backends = map[string]NewBackendFunc{
+	"ftp": NewFTPBackend,
+	"smb": NewSMBBackend,
+}
+
+// Will return nil if no backend is found.
+func GetBackend(id string) NewBackendFunc {
+	return backends[id]
+}