VScript: properly implement script command callback

Previously we did sq_pushroottable() and a subsequent sq_call() after compiling the text buffer, but this didn't work for code that was threaded, or using Get/SetNetVar* functions.

The second issue was that the callback for the "script" command was ran in the main thread. Server script should always run in the server frame thread, the Set/GetNetVar* functions check thread id to retrieve the correct VM context, so running server script from the main thread ended up with Set/GetNetVar* functions retrieving the client VM context rather than server's, causing undefined behavior.

Script commands are now queued to the server frame thread, ultimately fixing this bug.

Also fixed a small bug with function 'sq_compilebuffer()'; it takes an extra argument but this wasn't taken into account in the SDK.

src/engine/server/server.cpp

@@ -10,6 +10,7 @@
 /////////////////////////////////////////////////////////////////////////////////
 #include "core/stdafx.h"
 #include "common/protocol.h"
+#include "tier0/frametask.h"
 #include "tier1/cvar.h"
 #include "tier1/strtools.h"
 #include "engine/server/sv_main.h"
@@ -217,6 +218,17 @@ void CServer::BroadcastMessage(CNetMessage* const msg, const bool onlyActive, co
 //---------------------------------------------------------------------------------
 void CServer::FrameJob(double flFrameTime, bool bRunOverlays, bool bUpdateFrame)
 {
+	for (IFrameTask* const& task : g_ServerTaskQueueList)
+	{
+		task->RunFrame();
+	}
+
+	g_ServerTaskQueueList.erase(std::remove_if(g_ServerTaskQueueList.begin(), 
+		g_ServerTaskQueueList.end(), [](const IFrameTask* task)
+		{
+			return task->IsFinished();
+		}), g_ServerTaskQueueList.end());
+
 	CServer__FrameJob(flFrameTime, bRunOverlays, bUpdateFrame);
 	LiveAPISystem()->RunFrame();
 }
@@ -242,3 +254,6 @@ void VServer::Detour(const bool bAttach) const
 ///////////////////////////////////////////////////////////////////////////////
 CServer* g_pServer = nullptr;
 CClientExtended CServer::sm_ClientsExtended[MAX_PLAYERS];
+
+std::list<IFrameTask*> g_ServerTaskQueueList;
+CFrameTask g_ServerTaskQueue;

src/engine/server/server.h

@@ -1,4 +1,5 @@
 #pragma once
+#include "tier0/frametask.h"
 #include "tier1/NetAdr.h"
 #include "networksystem/pylon.h"
 #include "engine/client/client.h"
@@ -111,6 +112,9 @@ static_assert(sizeof(CServer) == 0x25264C0);
 
 extern CServer* g_pServer;
 
+extern std::list<IFrameTask*> g_ServerTaskQueueList;
+extern CFrameTask g_ServerTaskQueue;
+
 extern ConVar sv_showconnecting;
 
 extern ConVar sv_pylonVisibility;

src/engine/sys_dll.cpp

@@ -20,6 +20,7 @@
 #include "engine/host_cmd.h"
 #include "engine/enginetrace.h"
 #ifndef CLIENT_DLL
+#include "engine/server/server.h"
 #include "engine/server/sv_main.h"
 #include "server/vengineserver_impl.h"
 #include "game/server/gameinterface.h"
@@ -116,8 +117,11 @@ bool CModAppSystemGroup::StaticCreate(CModAppSystemGroup* pModAppSystemGroup)
 	}
 
 	g_TaskQueueList.push_back(&g_TaskQueue);
-	g_bAppSystemInit = true;
+#ifndef CLIENT_DLL
+	g_ServerTaskQueueList.push_back(&g_ServerTaskQueue);
+#endif // !CLIENT_DLL
 
+	g_bAppSystemInit = true;
 	return CModAppSystemGroup__Create(pModAppSystemGroup);
 }
 

src/game/server/vscript_server.cpp

@@ -31,6 +31,18 @@ static void SQVM_ServerScript_f(const CCommand& args)
 {
     if (args.ArgC() >= 2)
     {
+        const char* code = args.ArgS();
+
+        if (!ThreadInServerFrameThread())
+        {
+            const string scode(code);
+            g_ServerTaskQueue.Dispatch([scode]()
+                    {
+                        Script_Execute(scode.c_str(), SQCONTEXT::SERVER);
+                    }, 0);
+            return; // Only run in server frame thread.
+        }
+
         Script_Execute(args.ArgS(), SQCONTEXT::SERVER);
     }
 }

src/public/tier0/frametask.h

@@ -4,8 +4,8 @@
 #include "public/iframetask.h"
 
 //=============================================================================//
-// This class is set up to run before each frame (main thread).
-// Committed tasks are scheduled to execute after 'i' frames.
+// This class is set up to run before each frame, committed tasks are scheduled
+// to execute after 'i' frames.
 // ----------------------------------------------------------------------------
 // A use case for scheduling tasks in the main thread would be (for example)
 // performing a web request in a separate thread, and apply the results (such as

src/vscript/languages/squirrel_re/include/squirrel.h

@@ -187,7 +187,7 @@ void sq_newtable(HSQUIRRELVM v);
 SQRESULT sq_newslot(HSQUIRRELVM v, SQInteger idx);
 SQRESULT sq_arrayappend(HSQUIRRELVM v, SQInteger idx);
 SQRESULT sq_pushstructure(HSQUIRRELVM v, const SQChar* name, const SQChar* member, const SQChar* codeclass1, const SQChar* codeclass2);
-SQRESULT sq_compilebuffer(HSQUIRRELVM v, SQBufState* bufferState, const SQChar* buffer, SQInteger context);
+SQRESULT sq_compilebuffer(HSQUIRRELVM v, SQBufState* bufferState, const SQChar* buffer, SQInteger context, SQBool raiseerror);
 SQRESULT sq_call(HSQUIRRELVM v, SQInteger params, SQBool retval, SQBool raiseerror);
 
 SQRESULT sq_startconsttable(HSQUIRRELVM v);
@@ -228,7 +228,7 @@ inline void(*v_sq_newtable)(HSQUIRRELVM v);
 inline SQRESULT(*v_sq_newslot)(HSQUIRRELVM v, SQInteger idx);
 inline SQRESULT(*v_sq_arrayappend)(HSQUIRRELVM v, SQInteger idx);
 inline SQRESULT(*v_sq_pushstructure)(HSQUIRRELVM v, const SQChar* name, const SQChar* member, const SQChar* codeclass1, const SQChar* codeclass2);
-inline SQRESULT(*v_sq_compilebuffer)(HSQUIRRELVM v, SQBufState* bufferstate, const SQChar* buffer, SQInteger level);
+inline SQRESULT(*v_sq_compilebuffer)(HSQUIRRELVM v, SQBufState* bufferstate, const SQChar* buffer, SQInteger level, SQBool raiseerror);
 inline SQRESULT(*v_sq_call)(HSQUIRRELVM v, SQInteger params, SQBool retval, SQBool raiseerror);
 inline SQRESULT(*v_sq_get)(HSQUIRRELVM v, SQInteger idx);
 

src/vscript/languages/squirrel_re/squirrel/sqapi.cpp

@@ -177,9 +177,9 @@ SQRESULT sq_pushstructure(HSQUIRRELVM v, const SQChar* name, const SQChar* membe
 }
 
 //---------------------------------------------------------------------------------
-SQRESULT sq_compilebuffer(HSQUIRRELVM v, SQBufState* bufferState, const SQChar* buffer, SQInteger level)
+SQRESULT sq_compilebuffer(HSQUIRRELVM v, SQBufState* bufferState, const SQChar* buffer, SQInteger level, SQBool raiseerror)
 {
-	return v_sq_compilebuffer(v, bufferState, buffer, level);
+	return v_sq_compilebuffer(v, bufferState, buffer, level, raiseerror);
 }
 
 //---------------------------------------------------------------------------------

src/vscript/vscript.cpp

@@ -133,7 +133,11 @@ SQBool Script_PrecompileClientScripts(CSquirrelVM* vm)
 void Script_Execute(const SQChar* code, const SQCONTEXT context)
 {
 	Assert(context != SQCONTEXT::NONE);
-	Assert(ThreadInMainOrServerFrameThread());
+
+	if (context == SQCONTEXT::CLIENT || context == SQCONTEXT::UI)
+		Assert(ThreadInMainThread());
+	else if (context == SQCONTEXT::SERVER)
+		Assert(ThreadInServerFrameThread());
 
 	CSquirrelVM* s = Script_GetScriptHandle(context);
 	const char* const contextName = s_scriptContextNames[(int)context];
@@ -145,24 +149,29 @@ void Script_Execute(const SQChar* code, const SQCONTEXT context)
 	}
 
 	HSQUIRRELVM v = s->GetVM();
+
 	if (!v)
 	{
 		Error(eDLL_T::ENGINE, NO_ERROR, "Attempted to run %s script while VM isn't initialized\n", contextName);
 		return;
 	}
 
-	SQBufState bufState = SQBufState(code);
-	SQRESULT compileResult = sq_compilebuffer(v, &bufState, "console", -1);
+	SQBufState bufState(code);
 
-	if (SQ_SUCCEEDED(compileResult))
+	if (SQ_SUCCEEDED(sq_compilebuffer(v, &bufState, "unnamed", -1, SQTrue)))
 	{
-		sq_pushroottable(v);
-		SQRESULT callResult = sq_call(v, 1, false, false);
+		SQObject hScript;
+		sq_getstackobj(v, -1, &hScript);
 
-		if (!SQ_SUCCEEDED(callResult))
+		sq_addref(v, &hScript);
+		sq_pop(v, 1);
+
+		if (s->ExecuteFunction((HSCRIPT)&hScript, NULL, 0, NULL, NULL) == SCRIPT_ERROR)
 		{
 			Error(eDLL_T::ENGINE, NO_ERROR, "Failed to execute %s script \"%s\"\n", contextName, code);
 		}
+
+		sq_release(v, &hScript);
 	}
 }