public static unsafe void HackVTable(UObject obj)
{
// This will swap out the vtable entry and store the old one in our managed UClass
if (!Native_UObjectBaseUtility.IsA(obj.Address, Runtime.Classes.UClass))
{
UClass unrealClass = obj.GetClass();
if (unrealClass.VTableOriginalFunctions == null)
{
IntPtr *vtable = *(IntPtr **)obj.Address;
unrealClass.VTableOriginalFunctions = new Dictionary <int, UClass.VTableOriginalFunc>();
foreach (FunctionRedirect redirect in vtableRedirects)
{
if (!Native_UObjectBaseUtility.IsA(obj.Address, redirect.Class))
{
continue;
}
IntPtr originalFunctionAddress = vtable[redirect.VTableIndex];
if (originalFunctionAddress != redirect.NativeCallback)
{
IntPtr originalOwnerClassAddress = FindOriginalVTableOwner(
redirect.Class, unrealClass.Address, originalFunctionAddress, redirect.VTableIndex);
if (originalOwnerClassAddress != unrealClass.Address)
{
UClass originalOwnerClass = GCHelper.Find <UClass>(originalOwnerClassAddress);
if (originalOwnerClass.VTableOriginalFunctions == null)
{
HackVTable(originalOwnerClass.GetDefaultObject());
}
}
IntPtr pageAlignedPtr = FMemory.PageAlignPointer((IntPtr)(&vtable[redirect.VTableIndex]));
FMemory.PageProtect(pageAlignedPtr, (IntPtr)IntPtr.Size, true, true);
*(&vtable[redirect.VTableIndex]) = redirect.NativeCallback;
}
else
{
// The VTable has already been swapped out. Find the original function address.
UClass superClass = unrealClass;
while ((superClass = superClass.GetSuperClass()) != null && superClass.VTableOriginalFunctions == null)
{
}
Debug.Assert(superClass != null && superClass.VTableOriginalFunctions != null &&
superClass.VTableOriginalFunctions.ContainsKey(redirect.VTableIndex));
originalFunctionAddress = superClass.VTableOriginalFunctions[redirect.VTableIndex].FuncAddress;
}
unrealClass.VTableOriginalFunctions.Add(redirect.VTableIndex, new UClass.VTableOriginalFunc(originalFunctionAddress));
}
}
}
}
public static unsafe void Unload()
{
foreach (FunctionRedirect redirect in vtableRedirects)
{
using (FStringUnsafe dummyNameUnsafe = new FStringUnsafe(redirect.DummyName))
{
Native_VTableHacks.Set_VTableCallback(ref dummyNameUnsafe.Array, IntPtr.Zero);
}
}
// Restore the old vtable entry on hotreload. This is important as otherwise we would lose the original function address
// which is stored in the managed UClass (which gets destroyed on hotreload)
foreach (IntPtr objAddress in new NativeReflection.NativeObjectIterator(Runtime.Classes.UObject, EObjectFlags.NoFlags))
{
foreach (FunctionRedirect redirect in vtableRedirects)
{
if (!Native_UObjectBaseUtility.IsA(objAddress, redirect.Class))
{
continue;
}
IntPtr *vtable = *(IntPtr **)objAddress;
if (vtable[redirect.VTableIndex] == redirect.NativeCallback)
{
UObject obj = GCHelper.Find(objAddress);
Debug.Assert(obj != null);
UClass unrealClass = obj.GetClass();
Debug.Assert(unrealClass != null);
UClass.VTableOriginalFunc originalFunc;
if (unrealClass.VTableOriginalFunctions != null &&
unrealClass.VTableOriginalFunctions.TryGetValue(redirect.VTableIndex, out originalFunc))
{
IntPtr pageAlignedPtr = FMemory.PageAlignPointer((IntPtr)(&vtable[redirect.VTableIndex]));
FMemory.PageProtect(pageAlignedPtr, (IntPtr)IntPtr.Size, true, true);
*(&vtable[redirect.VTableIndex]) = originalFunc.FuncAddress;
}
}
}
}
}
