Fix crash on global or scenario script reload.

The string table of System.ocg scripts (except the global System.ocg) pointed to nowhere after the initial load phase, but is still required for reload. Added a ref counting option to keep these string tables alive.

src/c4group/C4LangStringTable.cpp

@@ -23,7 +23,7 @@
 #include "C4LangStringTable.h"
 #include "C4InputValidation.h"
 
-C4LangStringTable::C4LangStringTable() {}
+C4LangStringTable::C4LangStringTable() : ref_count(1) {}
 
 bool C4LangStringTable::HasTranslation(const std::string &text) const
 {

src/c4group/C4LangStringTable.h

@@ -30,6 +30,7 @@ class C4LangStringTable : public C4ComponentHost
 	typedef std::map<std::string, std::string> Table;
 	mutable Table strings;
 	void PopulateStringTable() const;
+	int32_t ref_count; // ref counter initialized to 1 on ctor; delete when zero is reached
 public:
 	C4LangStringTable();
 	const std::string &Translate(const std::string &text) const;
@@ -39,6 +40,9 @@ public:
 	void ReplaceStrings(StdStrBuf &rBuf);
 	void ReplaceStrings(const StdStrBuf &rBuf, StdStrBuf &rTarget);
 
+	void AddRef() { ++ref_count;  }
+	void DelRef() { if (!--ref_count) delete this; }
+
 	class NoSuchTranslation : public std::runtime_error
 	{
 	public:

src/game/C4Game.cpp

@@ -2827,14 +2827,14 @@ bool C4Game::LoadAdditionalSystemGroup(C4Group &parent_group)
 	char fn[_MAX_FNAME+1] = { 0 };
 	if (SysGroup.OpenAsChild(&parent_group, C4CFN_System))
 	{
-		C4LangStringTable SysGroupString;
-		C4Language::LoadComponentHost(&SysGroupString, SysGroup, C4CFN_ScriptStringTbl, Config.General.LanguageEx);
+		C4LangStringTable *pSysGroupString = new C4LangStringTable();
+		C4Language::LoadComponentHost(pSysGroupString, SysGroup, C4CFN_ScriptStringTbl, Config.General.LanguageEx);
 		// load custom scenario control definitions
 		if (SysGroup.FindEntry(C4CFN_PlayerControls))
 		{
 			Log("[!]Loading local scenario player control definitions...");
 			C4PlayerControlFile PlayerControlFile;
-			if (!PlayerControlFile.Load(SysGroup, C4CFN_PlayerControls, &SysGroupString))
+			if (!PlayerControlFile.Load(SysGroup, C4CFN_PlayerControls, pSysGroupString))
 			{
 				// non-fatal error here
 				Log("[!]Error loading scenario defined player controls");
@@ -2854,12 +2854,14 @@ bool C4Game::LoadAdditionalSystemGroup(C4Group &parent_group)
 			// host will be destroyed by script engine, so drop the references
 			C4ScriptHost *scr = new C4ExtraScriptHost();
 			scr->Reg2List(&ScriptEngine);
-			scr->Load(SysGroup, fn, Config.General.LanguageEx, &SysGroupString);
+			scr->Load(SysGroup, fn, Config.General.LanguageEx, pSysGroupString);
 		}
 		// if it's a physical group: watch out for changes
 		if (!SysGroup.IsPacked() && Game.pFileMonitor)
 			Game.pFileMonitor->AddDirectory(SysGroup.GetFullName().getData());
 		SysGroup.Close();
+		// release string table if no longer used
+		pSysGroupString->DelRef();
 	}
 	return true;
 }

src/script/C4ScriptHost.cpp

@@ -51,6 +51,11 @@ void C4ScriptHost::Clear()
 	LocalValues.Clear();
 	SourceScripts.clear();
 	SourceScripts.push_back(this);
+	if (stringTable)
+	{
+		stringTable->DelRef();
+		stringTable = NULL;
+	}
 	// remove includes
 	Includes.clear();
 	Appends.clear();
@@ -62,7 +67,12 @@ bool C4ScriptHost::Load(C4Group &hGroup, const char *szFilename,
 	// Base load
 	bool fSuccess = ComponentHost.Load(hGroup,szFilename,szLanguage);
 	// String Table
-	stringTable = pLocalTable;
+	if (stringTable != pLocalTable)
+	{
+		if (stringTable) stringTable->DelRef();
+		stringTable = pLocalTable;
+		if (stringTable) stringTable->AddRef();
+	}
 	// set name
 	ScriptName.Ref(ComponentHost.GetFilePath());
 	// preparse script
@@ -73,7 +83,13 @@ bool C4ScriptHost::Load(C4Group &hGroup, const char *szFilename,
 
 bool C4ScriptHost::LoadData(const char *szFilename, const char *szData, class C4LangStringTable *pLocalTable)
 {
-	stringTable = pLocalTable;
+	// String Table
+	if (stringTable != pLocalTable)
+	{
+		if (stringTable) stringTable->DelRef();
+		stringTable = pLocalTable;
+		if (stringTable) stringTable->AddRef();
+	}
 	ScriptName.Copy(szFilename);
 
 	StdStrBuf tempScript;