Add HookPluginUnload() and UnhookPluginUnload() functions

core/logic/PluginSys.cpp

@@ -1505,6 +1505,8 @@ void CPluginManager::Purge(CPlugin *plugin)
 			(*iter)->OnPluginUnloaded(plugin);
 	}
 
+	CallUnloadHooks(plugin);
+
 	plugin->DropEverything();
 
 	for (ListenerIter iter(m_listeners); !iter.done(); iter.next())
@@ -1601,6 +1603,19 @@ void CPluginManager::OnSourceModShutdown()
 
 	forwardsys->ReleaseForward(m_pOnLibraryAdded);
 	forwardsys->ReleaseForward(m_pOnLibraryRemoved);
+
+	{
+		std::list<PluginUnloadHookInfo>::iterator iter = m_PluginUnloadHooks.begin();
+	
+		while (iter!=m_PluginUnloadHooks.end())
+		{
+			forwardsys->ReleaseForward(iter->pForward);
+
+			iter++;
+		}
+
+		m_PluginUnloadHooks.clear();
+	}
 }
 
 ConfigResult CPluginManager::OnSourceModConfigChanged(const char *key,
@@ -2202,6 +2217,72 @@ bool CPluginManager::LibraryExists(const char *lib)
 	return false;
 }
 
+bool CPluginManager::HookPluginUnload(IPlugin *pPluginToHook, IPluginFunction *pHookFunction)
+{
+	{
+		std::list<PluginUnloadHookInfo>::iterator iter = m_PluginUnloadHooks.begin();
+
+		while (iter!=m_PluginUnloadHooks.end())
+		{
+			if(iter->pPluginTarget == pPluginToHook)
+			{
+				return iter->pForward->AddFunction(pHookFunction);
+			}
+
+			iter++;
+		}
+	}
+
+	IChangeableForward *pForward = forwardsys->CreateForwardEx(nullptr, ET_Hook, 1, nullptr, Param_Cell);
+
+	m_PluginUnloadHooks.push_back({pPluginToHook, pForward});
+
+	return pForward->AddFunction(pHookFunction);
+}
+
+bool CPluginManager::UnhookPluginUnload(IPlugin *pPluginToUnhook, IPluginFunction *pHookFunction)
+{
+	std::list<PluginUnloadHookInfo>::iterator iter = m_PluginUnloadHooks.begin();
+
+	while (iter!=m_PluginUnloadHooks.end())
+	{
+		if(iter->pPluginTarget == pPluginToUnhook)
+		{
+			return iter->pForward->RemoveFunction(pHookFunction);
+		}
+
+		iter++;
+	}
+
+	return false;
+}
+
+void CPluginManager::CallUnloadHooks(IPlugin *pTarget)
+{
+	std::list<PluginUnloadHookInfo>::iterator iter = m_PluginUnloadHooks.begin();
+
+	IChangeableForward *pForwardToCall;
+
+	while (iter!=m_PluginUnloadHooks.end())
+	{
+		// There can only be one unique
+		if(iter->pPluginTarget == pTarget)
+		{
+			pForwardToCall = iter->pForward;
+
+			pForwardToCall->PushCell((cell_t)pTarget);
+			pForwardToCall->Execute();
+
+			pForwardToCall->Cancel();
+			m_PluginUnloadHooks.erase(iter);
+
+			return;
+		}
+
+		iter++;
+	}
+}
+
 void CPluginManager::AllPluginsLoaded()
 {
 	for (PluginIter iter(m_plugins); !iter.done(); iter.next())

core/logic/PluginSys.h

@@ -425,6 +425,12 @@ public:
 
 	bool LibraryExists(const char *lib);
 
+	bool HookPluginUnload(IPlugin *pPluginToHook, IPluginFunction *pHookFunction);
+
+	bool UnhookPluginUnload(IPlugin *pPluginToUnhook, IPluginFunction *pHookFunction);
+
+	void CallUnloadHooks(IPlugin *pTarget);
+
 	bool ReloadPlugin(CPlugin *pl, bool print=false);
 
 	void UnloadAll();
@@ -523,6 +529,12 @@ private:
 	// Forwards
 	IForward *m_pOnLibraryAdded;
 	IForward *m_pOnLibraryRemoved;
+	struct PluginUnloadHookInfo
+	{
+		IPlugin *pPluginTarget;
+		IChangeableForward *pForward;
+	};
+	std::list<PluginUnloadHookInfo> m_PluginUnloadHooks;
 };
 
 extern CPluginManager g_PluginSys;

core/logic/smn_core.cpp

@@ -637,6 +637,34 @@ static cell_t FindPluginByNumber(IPluginContext *pContext, const cell_t *params)
 	return pPlugin->GetMyHandle();
 }
 
+static cell_t HookPluginUnload(IPluginContext *pContext, const cell_t *params)
+{
+	IPlugin *pPlugin = GetPluginFromHandle(pContext, params[1]);
+
+	if (!pPlugin)
+	{
+		return false;
+	}
+
+	IPluginFunction *pCallback = pContext->GetFunctionById(params[3]);
+
+	return scripts->HookPluginUnload(pPlugin, pCallback);
+}
+
+static cell_t UnhookPluginUnload(IPluginContext *pContext, const cell_t *params)
+{
+	IPlugin *pPlugin = GetPluginFromHandle(pContext, params[1]);
+
+	if (!pPlugin)
+	{
+		return false;
+	}
+
+	IPluginFunction *pCallback = pContext->GetFunctionById(params[3]);
+
+	return scripts->UnhookPluginUnload(pPlugin, pCallback);
+}
+
 static cell_t VerifyCoreVersion(IPluginContext *pContext, const cell_t *params)
 {
 	return 4;
@@ -969,6 +997,8 @@ REGISTER_NATIVES(coreNatives)
 	{"LogToFileEx",				LogToFileEx},
 	{"GetExtensionFileStatus",	GetExtensionFileStatus},
 	{"FindPluginByNumber",		FindPluginByNumber},
+	{"HookPluginUnload",		HookPluginUnload},
+	{"UnhookPluginUnload",		UnhookPluginUnload},
 	{"VerifyCoreVersion",		VerifyCoreVersion},
 	{"GetFeatureStatus",        GetFeatureStatus},
 	{"RequireFeature",          RequireFeature},