Fix config sync after freezing namespaces

This was accidentally broken by #9627 because during config sync, a config
validation happens that uses `--define System.ZonesStageVarDir=...` which fails
on the now frozen namespace.

This commit changes this to use `Internal.ZonesStageVarDir` instead. After all,
this is used for internal functionality, users should not directly interact
with this flag.

Additionally, it no longer freezes the `Internal` namespace which actually
allows using `Internal.ZonesStageVarDir` in the first place. This also fixes
`--define Internal.Debug*` which was also broken by said PR. Freezing of the
`Internal` namespace is not necessary for performance reasons as it's not
searched implicitly (for example when accessing `globals.x`) and should users
actually interact with it, they should know by that name that they are on their
own.

lib/base/scriptframe.cpp

@@ -11,7 +11,7 @@ using namespace icinga;
 
 boost::thread_specific_ptr<std::stack<ScriptFrame *> > ScriptFrame::m_ScriptFrames;
 
-static Namespace::Ptr l_SystemNS, l_StatsNS, l_InternalNS;
+static Namespace::Ptr l_SystemNS, l_StatsNS;
 
 /* Ensure that this gets called with highest priority
  * and wins against other static initializers in lib/icinga, etc.
@@ -36,14 +36,12 @@ INITIALIZE_ONCE_WITH_PRIORITY([]() {
 	l_StatsNS = new Namespace(true);
 	globalNS->Set("StatsFunctions", l_StatsNS, true);
 
-	l_InternalNS = new Namespace(true);
-	globalNS->Set("Internal", l_InternalNS, true);
+	globalNS->Set("Internal", new Namespace(true), true);
 }, InitializePriority::CreateNamespaces);
 
 INITIALIZE_ONCE_WITH_PRIORITY([]() {
 	l_SystemNS->Freeze();
 	l_StatsNS->Freeze();
-	l_InternalNS->Freeze();
 }, InitializePriority::FreezeNamespaces);
 
 ScriptFrame::ScriptFrame(bool allocLocals)

lib/cli/daemonutility.cpp

@@ -111,6 +111,9 @@ bool DaemonUtility::ValidateConfigFiles(const std::vector<std::string>& configs,
 	Namespace::Ptr systemNS = ScriptGlobal::Get("System");
 	VERIFY(systemNS);
 
+	Namespace::Ptr internalNS = ScriptGlobal::Get("Internal");
+	VERIFY(internalNS);
+
 	if (!objectsFile.IsEmpty())
 		ConfigCompilerContext::GetInstance()->OpenObjectsFile(objectsFile);
 
@@ -134,7 +137,7 @@ bool DaemonUtility::ValidateConfigFiles(const std::vector<std::string>& configs,
 	success = true;
 
 	/* Only load zone directory if we're not in staging validation. */
-	if (!systemNS->Contains("ZonesStageVarDir")) {
+	if (!internalNS->Contains("ZonesStageVarDir")) {
 		String zonesEtcDir = Configuration::ZonesDir;
 		if (!zonesEtcDir.IsEmpty() && Utility::PathExists(zonesEtcDir)) {
 			std::set<String> zoneEtcDirs;
@@ -177,8 +180,8 @@ bool DaemonUtility::ValidateConfigFiles(const std::vector<std::string>& configs,
 	String zonesVarDir = Configuration::DataDir + "/api/zones";
 
 	/* Cluster config sync stage validation needs this. */
-	if (systemNS->Contains("ZonesStageVarDir")) {
-		zonesVarDir = systemNS->Get("ZonesStageVarDir");
+	if (internalNS->Contains("ZonesStageVarDir")) {
+		zonesVarDir = internalNS->Get("ZonesStageVarDir");
 
 		Log(LogNotice, "DaemonUtility")
 			<< "Overriding zones var directory with '" << zonesVarDir << "' for cluster config sync staging.";

lib/remote/apilistener-filesync.cpp

@@ -554,7 +554,7 @@ void ApiListener::HandleConfigUpdate(const MessageOrigin::Ptr& origin, const Dic
 }
 
 /**
- * Spawns a new validation process with 'System.ZonesStageVarDir' set to override the config validation zone dirs with
+ * Spawns a new validation process with 'Internal.ZonesStageVarDir' set to override the config validation zone dirs with
  * our current stage. Then waits for the validation result and if it was successful, the configuration is copied from
  * stage to production and a restart is triggered. On validation failure, there is no restart and this is logged.
  *
@@ -584,7 +584,7 @@ void ApiListener::TryActivateZonesStage(const std::vector<String>& relativePaths
 
 	// Set the ZonesStageDir. This creates our own local chroot without any additional automated zone includes.
 	args->Add("--define");
-	args->Add("System.ZonesStageVarDir=" + GetApiZonesStageDir());
+	args->Add("Internal.ZonesStageVarDir=" + GetApiZonesStageDir());
 
 	Process::Ptr process = new Process(Process::PrepareCommand(args));
 	process->SetTimeout(Application::GetReloadTimeout());