From d59f67216a53ae085fef1a8992cf8c4c450b78fc Mon Sep 17 00:00:00 2001
From: LukeFZ <17146677+LukeFZ@users.noreply.github.com>
Date: Sun, 13 Oct 2024 21:54:59 +0200
Subject: [PATCH] support auto-recovering type indices from type handles fixes
 loading of memory-dumped v29+ libraries since those replacee their class
 indices on load with a pointer to the corresponding type

---
 Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs | 47 +++++++++++++++++--
 .../Next/BinaryMetadata/Il2CppTypeEnum.cs     | 31 ++++++++++++
 2 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs b/Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs
index ab7c7aa..64b087f 100644
--- a/Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs
+++ b/Il2CppInspector.Common/IL2CPP/Il2CppBinary.cs
@@ -6,15 +6,12 @@
 */
 
 using Il2CppInspector.Next;
-using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
-using System.IO;
-using System.Linq;
 using System.Reflection;
 using System.Text.RegularExpressions;
 using Il2CppInspector.Next.BinaryMetadata;
+using Il2CppInspector.Next.Metadata;
 using VersionedSerialization;
 
 namespace Il2CppInspector
@@ -370,6 +367,48 @@ namespace Il2CppInspector
             
             TypeReferences = Image.ReadMappedVersionedObjectPointerArray<Il2CppType>(MetadataRegistration.Types, (int)MetadataRegistration.TypesCount);
 
+            if (TypeReferences.Any(x => 
+                    x.Type.IsTypeDefinitionEnum() 
+                    && (uint)x.Data.KlassIndex >= (uint)Metadata.Types.Length))
+            {
+                // This is a memory-dumped binary.
+                // We need to fix the remapped type indices from their pointer form back to the indices.
+                var baseDefinitionPtr = ulong.MaxValue;
+                var baseGenericPtr = ulong.MaxValue;
+
+                foreach (var entry in TypeReferences)
+                {
+                    if (entry.Type.IsTypeDefinitionEnum())
+                    {
+                        baseDefinitionPtr = Math.Min(baseDefinitionPtr, entry.Data.Type.PointerValue);
+                    }
+                    else if (entry.Type.IsGenericParameterEnum())
+                    {
+                        baseGenericPtr = Math.Min(baseGenericPtr, entry.Data.GenericParameterHandle.PointerValue);
+                    }
+
+                }
+
+                var definitionSize = (ulong)Il2CppTypeDefinition.Size(Image.Version);
+                var genericParameterSize = (ulong)Il2CppGenericParameter.Size(Image.Version);
+
+                var builder = ImmutableArray.CreateBuilder<Il2CppType>(TypeReferences.Length);
+                for (var i = 0; i < TypeReferences.Length; i++)
+                {
+                    var type = TypeReferences[i];
+                    if (type.Type.IsTypeDefinitionEnum())
+                    {
+                        type.Data.Value = (type.Data.Type.PointerValue - baseDefinitionPtr) / definitionSize;
+                    }
+                    else if (type.Type.IsGenericParameterEnum())
+                    {
+                        type.Data.Value = (type.Data.Type.PointerValue - baseGenericPtr) / genericParameterSize;
+                    }
+                    builder.Add(type);
+                }
+                TypeReferences = builder.MoveToImmutable();
+            }
+
             // Custom attribute constructors (function pointers)
             // This is managed in Il2CppInspector for metadata >= 27
             if (Image.Version < MetadataVersions.V270) {
diff --git a/Il2CppInspector.Common/Next/BinaryMetadata/Il2CppTypeEnum.cs b/Il2CppInspector.Common/Next/BinaryMetadata/Il2CppTypeEnum.cs
index 0c44142..7466ad9 100644
--- a/Il2CppInspector.Common/Next/BinaryMetadata/Il2CppTypeEnum.cs
+++ b/Il2CppInspector.Common/Next/BinaryMetadata/Il2CppTypeEnum.cs
@@ -42,4 +42,35 @@ public enum Il2CppTypeEnum : byte
 
     IL2CPP_TYPE_ENUM = 0x55,
     IL2CPP_TYPE_IL2CPP_TYPE_INDEX = 0xff
+}
+
+public static class Il2CppTypeEnumExtensions
+{
+    public static bool IsTypeDefinitionEnum(this Il2CppTypeEnum value)
+        => value
+            is Il2CppTypeEnum.IL2CPP_TYPE_VOID
+            or Il2CppTypeEnum.IL2CPP_TYPE_BOOLEAN
+            or Il2CppTypeEnum.IL2CPP_TYPE_CHAR
+            or Il2CppTypeEnum.IL2CPP_TYPE_I1
+            or Il2CppTypeEnum.IL2CPP_TYPE_U1
+            or Il2CppTypeEnum.IL2CPP_TYPE_I2
+            or Il2CppTypeEnum.IL2CPP_TYPE_U2
+            or Il2CppTypeEnum.IL2CPP_TYPE_I4
+            or Il2CppTypeEnum.IL2CPP_TYPE_U4
+            or Il2CppTypeEnum.IL2CPP_TYPE_I8
+            or Il2CppTypeEnum.IL2CPP_TYPE_U8
+            or Il2CppTypeEnum.IL2CPP_TYPE_R4
+            or Il2CppTypeEnum.IL2CPP_TYPE_R8
+            or Il2CppTypeEnum.IL2CPP_TYPE_STRING
+            or Il2CppTypeEnum.IL2CPP_TYPE_VALUETYPE
+            or Il2CppTypeEnum.IL2CPP_TYPE_CLASS
+            or Il2CppTypeEnum.IL2CPP_TYPE_I
+            or Il2CppTypeEnum.IL2CPP_TYPE_U
+            or Il2CppTypeEnum.IL2CPP_TYPE_OBJECT
+            or Il2CppTypeEnum.IL2CPP_TYPE_TYPEDBYREF;
+
+    public static bool IsGenericParameterEnum(this Il2CppTypeEnum value)
+        => value
+            is Il2CppTypeEnum.IL2CPP_TYPE_VAR
+            or Il2CppTypeEnum.IL2CPP_TYPE_MVAR;
 }
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