Modifying cg_shadows when running dll gamecode crashes at vid_restart

[illwieckz]

Setting cg_shadows with value greater than 1 crashes the game (engine quits, and the calling terminal is left in a garbage state). Options greater than 1 were riddled with bugs and were not working, and the Unvanquished graphic option UI does not make possible to set values higher than 1, but it's possible to do it on command line and some players may have an old config using them.

[illwieckz]

The crash also happens with value 0.

The crash happens on ASSERT_NQ(cvar->proxy, nullptr); line in Cvar::SetLatchedValues():

Daemon/src/engine/framework/CvarSystem.cpp

Lines 479 to 498 in 075128e

	void SetLatchedValues()
	{
	for (auto& entry : GetCvarMap()) {
	cvarRecord_t* cvar = entry.second;
	if (!cvar->latchedValue) {
	continue;
	}
	cvar->value = std::move(*cvar->latchedValue);
	cvar->latchedValue = Util::nullopt;
	SetCCvar(*cvar);
	ASSERT_NQ(cvar->proxy, nullptr);
	OnValueChangedResult result = cvar->proxy->OnValueChanged(cvar->value);
	if (result.success) {
	ChangeCvarDescription(entry.first, cvar, result.description);
	} else {
	Log::Warn("BUG: failed setting cvar %s to latched value", entry.first);
	}
	}
	setLatchedValuesCalled = true;
	}

Trace:

#0  Cvar::SetLatchedValues() at …/Daemon/src/engine/framework/CvarSystem.cpp:489
#1  CL_StartHunkUsers() at …/Daemon/src/engine/client/cl_main.cpp:2659
#2  CL_Vid_Restart_f() at …/Daemon/src/engine/client/cl_main.cpp:1487
#3  ProxyCmd::Run(this = 0x5555559fe060 <myProxyCmd>, args = ) at …/Daemon/src/engine/qcommon/cmd.cpp:446
#4  Cmd::ExecuteCommand(command = , parseCvars = true, env = 0x0) at …/Daemon/src/engine/framework/CommandSystem.cpp:215
#5  Cmd::ExecuteCommandBuffer() at …/Daemon/src/engine/framework/CommandSystem.cpp:93
#6  Com_Frame() at …/Daemon/src/engine/qcommon/common.cpp:975
#7  Application::ClientApplication::Frame(this = 0x555555e90100 <Application::GetApp()::app>) at …/Daemon/src/engine/client/ClientApplication.cpp:84
#8  Application::Frame() at …/Daemon/src/engine/framework/Application.cpp:73
#9  main(argc = 43, argv = 0x7fffffffdb58) at …/Daemon/src/engine/framework/System.cpp:717

[illwieckz]

This cvar is defined both by Dæmon engine and Unvanquished game code.

Dæmon:

src/engine/renderer/tr_local.h
2931:	extern cvar_t *r_shadows; // controls shadows: 0 = none, 1 = blur, 2 = black planar projection,

src/engine/renderer/tr_init.cpp
112:	cvar_t      *r_shadows;
1249:		r_shadows = ri.Cvar_Get( "cg_shadows", "1", 0 );

Unvanquished:

src/cgame/cg_local.h
1737:extern Cvar::Range<Cvar::Cvar<int>> cg_shadows;

src/cgame/cg_main.cpp
46:Cvar::Range<Cvar::Cvar<int>> cg_shadows("cg_shadows", "type of shadows to draw", Cvar::LATCH, 1, 0, 6);

[illwieckz]

I don't know how to fix this.

Note: the crash happens with dll cgame, not with nexe.

[illwieckz]

It was probably fixed by #606.

[illwieckz]

After this commit no dynamic shadow is rendered but at least there
is no crash when setting to cg_shadows a value greater than 1 to
enable dynamic shadowing.