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Fix XrefScanUtilFinder for 32 bit games #222

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Fix XrefScanUtilFinder for 32 bit games #222

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84290ca
Fix XrefScanUtilFinder for 32 bit games
Dustin21335 Jul 30, 2025
8a4f98a
Update XrefScanUtilFinder.cs
Dustin21335 Jul 30, 2025
8543232
Update Il2CppInterop.Common/XrefScans/XrefScanUtilFinder.cs
Dustin21335 Jul 30, 2025
fcf7a39
Update Il2CppInterop.Common/XrefScans/XrefScanUtilFinder.cs
Dustin21335 Jul 30, 2025
e46b67a
Update Il2CppInterop.Common/XrefScans/XrefScanUtilFinder.cs
Dustin21335 Jul 30, 2025
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4 changes: 2 additions & 2 deletions Il2CppInterop.Common/XrefScans/XrefScanUtilFinder.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ public static IntPtr FindLastRcxReadAddressBeforeCallTo(IntPtr codeStart, IntPtr
if (instruction.Op0Kind == OpKind.Register && instruction.Op0Register == Register.ECX &&
instruction.Op1Kind == OpKind.Memory && instruction.IsIPRelativeMemoryOperand)
{
var movTarget = (IntPtr)instruction.IPRelativeMemoryAddress;
var movTarget = new IntPtr(unchecked((long)instruction.IPRelativeMemoryAddress));
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@ds5678 ds5678 Jul 30, 2025

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Why does this fix the problem?

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@Dustin21335 Dustin21335 Jul 30, 2025

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image

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@ds5678 ds5678 Jul 30, 2025

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Exactly. Why does this not throw too?

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@Dustin21335 Dustin21335 Jul 30, 2025

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It converts the ulong to a long with unchecked wrapping, then creates a new IntPtr

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/checked-and-unchecked

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@ds5678 ds5678 Jul 30, 2025

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The only ways I see that not throwing is either:

  • The ulong value is less than or equal to int.MaxValue.
  • The ulong value is greater than ulong.MaxValue + int.MinValue.

Is it guaranteed to be in these ranges?

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@Dustin21335 Dustin21335 Jul 30, 2025 •
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Oh yea your right I apologize. I believe this would work without throwing

IntPtr movTarget;

if (Environment.Is64BitProcess) movTarget = address <= long.MaxValue ? new IntPtr((long)address) : new IntPtr(unchecked((long)address)); 
else movTarget = address <= int.MaxValue ? new IntPtr((int)address) : new IntPtr(unchecked((int)address));

if (instruction.MemorySize != MemorySize.UInt32 && instruction.MemorySize != MemorySize.Int32)
continue;

Expand Down Expand Up @@ -72,7 +72,7 @@ public static IntPtr FindByteWriteTargetRightAfterCallTo(IntPtr codeStart, IntPt
if (instruction.Mnemonic == Mnemonic.Mov && seenCall)
if (instruction.Op0Kind == OpKind.Memory && (instruction.MemorySize == MemorySize.Int8 ||
instruction.MemorySize == MemorySize.UInt8))
return (IntPtr)instruction.IPRelativeMemoryAddress;
return new IntPtr(unchecked((long)instruction.IPRelativeMemoryAddress));
}
}

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