GetINISetting crashes for fallout4prefs.ini or basic help with modding

[ArthurHub]

I'm looking into doing improvements to non-on-wrist PipBoy interaction like in-front. But I got stuck being able to get the player PipBoy setting with crash in F4SEVR and I don't know how to proceed.

Seeing as the config is saved into fallout4prefs.ini it made sense to use GetINISetting:

Setting* set = GetINISetting("bAttachPipboyToHMD:VR");

Unfortunately, it crashes for any values in fallout4prefs. Crash log (trimmed):

Unhandled exception "EXCEPTION_ACCESS_VIOLATION" at 0x7FFF120C92E4 FRIK.dll+00E92E4	mov rax, [rax]
...
PROBABLE CALL STACK:
	[0] 0x7FFF120C92E4       FRIK.dll+00E92E4	mov rax, [rax] |  C:\Stuff\github\f4sevr\src\f4sevr\f4se\GameSettings.cpp:124 ?Get@SettingCollectionList@@QEAAPEAVSetting@@PEBD@Z
	[1] 0x7FFF120C9551       FRIK.dll+00E9551	mov [rbp+0x08], rax |  C:\Stuff\github\f4sevr\src\f4sevr\f4se\GameSettings.cpp:105 ?GetINISetting@@YAPEAVSetting@@PEBD@Z C:\Stuff\github\f4sevr\src\f4sevr\f4se\GameSettings.cpp:17 ?GetINISetting@@YAPEAVSetting@@PEBD@Z
	[2] 0x7FFF12022BEC       FRIK.dll+0042BEC	mov [rbp+0xE8], rax |  C:\Stuff\github\Fallout-4-VR-Body\F4VRBody.cpp:1042 ?
...

The relevant code in F4SEVR GameSettings.cpp:

// 5B1FD95B3A1729A1781BED06D47E1A47EB6D89F2+91
RelocPtr <INISettingCollection *> g_iniSettings(0x05F33A30);
// 239A2F4B85F2D36A7E4E77D681108A197210AE0B+1C3
RelocPtr <INIPrefSettingCollection*> g_iniPrefSettings(0x05942F80);

Setting * GetINISetting(const char * name)
{
	Setting	* setting = (*g_iniSettings)->Get(name);
	if(!setting)
		setting = (*g_iniPrefSettings)->Get(name);  // line 105     <-------------

	return setting;
}

Setting * SettingCollectionList::Get(const char * name)
{
	Node * node = data;
	do
	{
		Setting * setting = node->data; // line 124        <-------------
		if(setting) {
			BSAutoFixedString searchName(name);
			BSAutoFixedString settingName(setting->name);
			if(searchName == settingName) {
				return setting;
			}
		}

		node = node->next;
	} while(node);

	return nullptr;
}

So, it looks like g_iniPrefSettings unlike g_iniSettings doesn't have the data field pointer correct in memory.

Questions:

1. Could it be that the memory reference 0x05942F80 is incorrect?
2. What do you do next?

p.s. I tried to see if I can find answers in discord but I can't find any relevant modding questions. It feels wasteful to get an answer there that will be lost the next day. Am I missing something? is there a specific discord group? Where would you look for answers for this?

cc @rollingrock @CylonSurfer

Huge thanks for your input!

[rollingrock]

This feels familiar. I'll look in ghidra when I get home

[ArthurHub]

I tried using Ghidra and IDA but was completely lost.
If you can put a few words or screenshots on what you do there it would be super helpful so I can contribute too.

Thank you!!!

[rollingrock]

well i need to do a merge of my ghidra as i have two enviroments right now. one that has a ton of symbols and labels from various sources i've collected through the years plus some of my own RE and another that's fresh and uses our custom ghidra branch that can import in the commonlib pdb to fix up classes and vtables through RTTI analysis.

i need to figure out how to merge them together then i can probably dump out everything in one go for people to use.

if you're interested in messing with that branch you can see my ghidra fork and alantse's PR with instructions here:
rollingrock/ghidra#3

[rollingrock]

a basic ghidra setup tutorial is here in case you haven't run steamless on your executables and things like that:
https://github.com/Starfield-Reverse-Engineering/Ghidra-Tutorial

[rollingrock]

finally you can probably hit me up on discord (rollingrock) and maybe i can just run a dump of what i got and send you

[rollingrock]

as for the question you originally asked it all looks fine to me. so i would ask where are you actually calling the GetINISetting in your code?

[rollingrock]

So the native function might be a little more robust than the f4se version. It has a null check before trying to assign value. Here's the decompiled version of it from the game binary:

Setting * SettingCollectionList::Get(SettingCollectionList<Setting> *this,char *name)

{
  int iVar1;
  node_type *node;
  Setting *setting;
  
  if ((name == (char *)0x0) || (node = &(this->settings)._root, node == (node_type *)0x0)) {
    return (Setting *)0x0;
  }
  do {
    if ((node->next == (node_type *)0x0) && (node->value == (Setting *)0x0)) {
      return (Setting *)0x0;
    }
    setting = (Setting *)node->value;
    iVar1 = _stricmp((setting->Setting_data)._key,name);
    if (iVar1 == 0) {
      return setting;
    }
    node = node->next;
  } while (node != (node_type *)0x0);
  return (Setting *)0x0;
}

I have a hook for it in frik in utils you'll see. i probably hooked it for a reason lol

[ArthurHub]

I did see the "native" one and tried it with the same result:

Unhandled exception "EXCEPTION_ACCESS_VIOLATION" at 0x7FF73227153B Fallout4VR.exe+050153B	mov rcx, [rdi+0x10]
PROBABLE CALL STACK:
	[0] 0x7FF73227153B Fallout4VR.exe+050153B	mov rcx, [rdi+0x10] |  SettingCollectionList<Setting>::GetPtr(char_*)_50153B -> 504957+0x3B	mov rcx, [rdi+0x10]
	[1] 0x7FFF5713C0C5       FRIK.dll+009C0C5	mov [rbp+0x08], rax |  C:\Stuff\github\Fallout-4-VR-Body\utils.cpp:372 ?GetINISettingNative@F4VRBody@@YAPEAVSetting@@PEBD@Z C:\Stuff\github\Fallout-4-VR-Body\utils.cpp:168 ?GetINISettingNative@F4VRBody@@YAPEAVSetting@@PEBD@Z
	[2] 0x7FFF570E2C53       FRIK.dll+0042C53	mov [rbp+0x128], rax |  C:\Stuff\github\Fallout-4-VR-Body\F4VRBody.cpp:1048 ?update@F4VRBody@@YAXXZ

Isn't those two codes are identical? one is OOP style and the other is going under the hood?

Setting* GetINISettingNative(const char* name)
{
	Setting* setting = SettingCollectionList_GetPtr(*g_iniSettings, name);
	if (!setting) {
		setting = SettingCollectionList_GetPtr(*g_iniPrefSettings, name);
	}

	return setting;
}

Setting * GetINISetting(const char * name)
{
	Setting	* setting = (*g_iniSettings)->Get(name);
	if(!setting)
		setting = (*g_iniPrefSettings)->Get(name);

	return setting;
}

[rollingrock]

the native function has a couple more checks but i guess that's not helping here.

it's choking on this statement

iVar1 = _stricmp((setting->Setting_data)._key,name);

which means there is a valid pointer to the setting but it doesn't have data.

so yeah i think what's happening here is they forgot to give it initialization data when they made the vr port so it has to be defined from the custom.ini i guess to get data and not crash.

[ArthurHub]

I see, and it's not possible that the memory reference of g_iniPrefSettings is incorrect?

the decompiled code is using ghidra?

[rollingrock]

no that address is fine. i think it's just simply the game doesn't initialize that particular setting anywhere until it reads it from the custom.ini unlike other settings