RAUC: marking FW slots as failed, or preferred for the next reboot

There's deliberately no way of marking a slot as correct via YANG. I
think that bypassing the internal safety mechanisms is not a reasonable
feature to be exported over a public API.

Change-Id: I24843f7062b2849c1df18ab6457080d40c6b09cf
diff --git a/src/system/RAUC.cpp b/src/system/RAUC.cpp
index 7360e91..f453aed 100644
--- a/src/system/RAUC.cpp
+++ b/src/system/RAUC.cpp
@@ -132,6 +132,15 @@
     m_dbusObjectProxyMethods->callMethod("InstallBundle").onInterface(INTERFACE).withArguments(source, std::map<std::string, sdbus::Variant> {});
 }
 
+/** @brief Mark a given slot as active/good/...
+ *
+ * This wraps RAUC's DBus method `Mark`.
+ */
+void RAUC::mark(const std::string& how, const std::string& slot)
+{
+    m_dbusObjectProxyMethods->callMethod("Mark").onInterface(INTERFACE).withArguments(how, slot);
+}
+
 std::string RAUC::operation() const
 {
     return m_dbusObjectProxyMethods->getProperty("Operation").onInterface(INTERFACE);