Access violation when trying to get field value

[Patrick-van-Halm]

I am trying to add a light component to the camera which is stored in the player class stored in an obfuscated value

IL2CPP::Thread::Attach(IL2CPP::Domain::Get());
Unity::il2cppClass* unityEngineLightType = IL2CPP::Class::Find("UnityEngine.Light");
Unity::il2cppObject* unityEngineLightInstance = Unity::Object::New(unityEngineLightType);
Unity::CComponent* playerInstance = Unity::Object::FindObjectOfType<Unity::CComponent>("Player");
Unity::CCamera* cam = playerInstance->GetMemberValue<Unity::CCamera*>("ഠപര\u0D3Bബഢരഫധ");
cam->AddComponent(unityEngineLightInstance);
Unity::CComponent* unityEngineLightComponent = cam->GetComponent("UnityEngine.Light");
unityEngineLightComponent->SetPropertyValue<float>("intensity", 10);
IL2CPP::Thread::Detach(IL2CPP::Domain::Get());

And I am getting an error within GetMemberValue

Unity::il2cppFieldInfo* pField = reinterpret_cast<Unity::il2cppFieldInfo * (IL2CPP_CALLING_CONVENTION)(void*, const char*)>(Functions.m_ClassGetFieldFromName)(m_Object.m_pClass, m_pMemberName);

Unity version: 2022.3.5f1 Error: Access violation reading location 0xFFFFFFFFFFFFFFFF

[sneakyevil]

You could wrap the string in u8"..." if that doesn't work maybe best way would be to use get all fields and cache the offset and read it directly.

[Patrick-van-Halm]

So I tried both, the u8 method throws the same error and getting all fields causes also a access violation writing location.

Within the GetFields method

return reinterpret_cast<Unity::il2cppFieldInfo * (IL2CPP_CALLING_CONVENTION)(void*, void**)>(Functions.m_ClassGetFields)(m_pClass, m_pIterator);

std::vector<Unity::il2cppFieldInfo*> fields;
playerInstance->FetchFields(&fields);

for (Unity::il2cppFieldInfo* field : fields) {
      std::cout << field->m_pName << std::endl; // Just so I can add a breakpoint
}

Am I possibly accessing a class wrong? I am going to try and run it within a different application to see if it works there.

[Patrick-van-Halm]

Alright with a quick test on a different game I found the issue. It seems like

Unity::CComponent* playerInstance = Unity::Object::FindObjectOfType<Unity::CComponent>("Player");

returns an incorrect pointer. If I look at the debug information the m_pName is not equal to "Player" but rather equal to "ðžê—z".

[Patrick-van-Halm]

And when I change the type to Unity::il2cppClass it does contain the correct name. So I assume the definition of the Unity components are changed so I will look into that

[Patrick-van-Halm]

It also seems like the flag "UNITY_VERSION_2022_3_8F1" is an incorrect version I currently have traced it back to Unity 2021.3.27f1

[extremeblackliu]

It also seems like the flag "UNITY_VERSION_2022_3_8F1" is an incorrect version I currently have traced it back to Unity 2021.3.27f1

this flag is used for unity version that higher than 2022.3.8, your problem can be solve by using field offset from target class. seems you are trying to add a light component to camera, if the camera is the eye camera, you can try get the camera from static class Camera by calling Camera.get_current() or Camera.get_main()

[karaok1]

Alright with a quick test on a different game I found the issue. It seems like

Unity::CComponent* playerInstance = Unity::Object::FindObjectOfType<Unity::CComponent>("Player");

returns an incorrect pointer. If I look at the debug information the m_pName is not equal to "Player" but rather equal to "ðžê—z�".

The problem might be that you are searching for the player, but the player is probably a GameObject rather than being a Component. They are different things in Unity. The former one has an instance and is an object in the hierarchy but a component is not.

[Patrick-van-Halm]

Alright with a quick test on a different game I found the issue. It seems like

Unity::CComponent* playerInstance = Unity::Object::FindObjectOfType<Unity::CComponent>("Player");

returns an incorrect pointer. If I look at the debug information the m_pName is not equal to "Player" but rather equal to "ðžê—z�".

The problem might be that you are searching for the player, but the player is probably a GameObject rather than being a Component. They are different things in Unity. The former one has an instance and is an object in the hierarchy but a component is not.

I know the difference however in using Il2CppDumper it specifically mentions Player in the root namespace. The class also returns correctly with the corresponding class so yes it's a component.

[Patrick-van-Halm]

It also seems like the flag "UNITY_VERSION_2022_3_8F1" is an incorrect version I currently have traced it back to Unity 2021.3.27f1

this flag is used for unity version that higher than 2022.3.8, your problem can be solve by using field offset from target class. seems you are trying to add a light component to camera, if the camera is the eye camera, you can try get the camera from static class Camera by calling Camera.get_current() or Camera.get_main()

I know its just accessing other classes causes the same error...

[extremeblackliu]

I know the difference however in using Il2CppDumper it specifically mentions Player in the root namespace. The class also returns correctly with the corresponding class so yes it's a component.

see

The problem might be that you are searching for the player, but the player is probably a GameObject rather than being a Component. They are different things in Unity. The former one has an instance and is an object in the hierarchy but a component is not.

game obfuscate doesn't affects system classes like gameobject, transform, camera ... etc, so when you get their classname, you should have non-obfuscate name or you messed up. try get it as gameobject then get the component which is you need from the gameobject. this step is literally same as you writing c# script for unity, just think it.

[extremeblackliu]

also, own thread is not recommended, its very unstable and randomly crashes. use https://sneakyevil.gitbook.io/il2cpp-resolver/callback/onupdate for instead

[karaok1]

May I ask, which game is this?

[Patrick-van-Halm]

also, own thread is not recommended, its very unstable and randomly crashes. use https://sneakyevil.gitbook.io/il2cpp-resolver/callback/onupdate for instead

Also tried this without any luck

[Patrick-van-Halm]

May I ask, which game is this?

Phasmophobia