Fix crashes on Unity 2020.1+, update changelog

ReleaseChangelog.md

@@ -1,13 +1,5 @@
-This is a small bugfix update. Generated assemblies should be mostly compatible with those generated by 0.4.14.0.  
-Some external tools that relied on native struct definitions might break though - some structs were moved to used the wrapper model.  
+This is a small bugfix update. Generated assemblies should be mostly compatible with those generated by 0.4.15.1.   
 Changes:
- * Generic structs are now always (correctly) generated as non-blittable
- * Rewrote native struct handling to enable easy support of different Unity versions.
-   * This release should, in theory, support all Unity versions from 2017.1.0 to 2020.2.x and perhaps even above. However, bugs are still a thing.
-   * The base of this was contributed by @ghorsington in #35
-   * Some fixes and improvements here were contributed by @ds5678 (#39)
- * Added `Il2CppObjectBase.WasCollected` (contributed by @ds5678 in #37)
- * Added basic support for loading custom components (of injected types) from assetbundles (contributed by @ds5678 in #38)
- * Added an overload of `Il2CppType.Of` method that doesn't throw exceptions for non-found types (contributed by @ds5678 in #36)
- * Field writes now use `il2cpp_gc_wbarrier_set_field` if it exists in GameAssembly
+ * Added `ClassInjectionAssemblyTargetAttribute` (contributed by @ds5678 in #49)
+ * Fixed crashes on Unity 2020.1.x and later
 

UnhollowerBaseLib/ClassInjector.cs

@@ -19,15 +19,15 @@ namespace UnhollowerRuntimeLib
 {
     public unsafe static class ClassInjector
     {
-        private static readonly Il2CppAssembly* FakeAssembly;
-        private static readonly INativeImageStruct FakeImage;
+        private static Il2CppAssembly* FakeAssembly;
+        private static INativeImageStruct FakeImage;
 
         /// <summary> type.FullName </summary>
         private static readonly HashSet<string> InjectedTypes = new HashSet<string>();
         /// <summary> namespace, class, image, pointer </summary>
         private static readonly Dictionary<(string, string, IntPtr), IntPtr> ClassFromNameDictionary = new Dictionary<(string, string, IntPtr), IntPtr>();
 
-        static ClassInjector()
+        static void CreateFakeAssembly()
         {
             FakeAssembly = (Il2CppAssembly*) Marshal.AllocHGlobal(Marshal.SizeOf<Il2CppAssembly>());
             FakeImage = UnityVersionHandler.NewImage(); //(Il2CppImage*) Marshal.AllocHGlobal(Marshal.SizeOf<Il2CppImage>());
@@ -104,6 +104,7 @@ public static void RegisterTypeInIl2Cpp(Type type, bool logSuccess)
 
             if (ourOriginalTypeToClassMethod == null) HookClassFromType();
             if (originalClassFromNameMethod == null) HookClassFromName();
+            if (FakeAssembly == null) CreateFakeAssembly();
 
             var classPointer = UnityVersionHandler.NewClass(baseClassPointer.VtableCount);
 

UnhollowerBaseLib/Runtime/VersionSpecific/Image/Images_27.cs

@@ -8,11 +8,15 @@ public unsafe class NativeImageStructHandler_27 : INativeImageStructHandler
     {
         public INativeImageStruct CreateNewImageStruct()
         {
-            var pointer = Marshal.AllocHGlobal(Marshal.SizeOf<Il2CppImageU2019>());
+            var pointer = (Il2CppImageU2019*) Marshal.AllocHGlobal(Marshal.SizeOf<Il2CppImageU2019>());
+            var metadataPointer = (Il2CppImageGlobalMetadata*) Marshal.AllocHGlobal(Marshal.SizeOf<Il2CppImageGlobalMetadata>());
 
-            *(Il2CppImageU2019*)pointer = default;
+            *pointer = default;
+            *metadataPointer = default;
+            pointer->metadataHandle = metadataPointer;
+            metadataPointer->image = pointer;
 
-            return new NativeImageStruct(pointer);
+            return new NativeImageStruct((IntPtr) pointer);
         }
 
         public INativeImageStruct Wrap(Il2CppImage* imagePointer)
@@ -32,7 +36,7 @@ private struct Il2CppImageU2019
             public uint exportedTypeCount;
             public uint customAttributeCount;
 
-            public IntPtr metadataHandle;
+            public Il2CppImageGlobalMetadata* metadataHandle;
 
             public /*Il2CppNameToTypeDefinitionIndexHashTable **/ IntPtr nameToClassHashTable;
             public IntPtr codeGenModule;
@@ -41,6 +45,16 @@ private struct Il2CppImageU2019
             public byte dynamic;
         }
 
+        [StructLayout(LayoutKind.Sequential)]
+        private struct Il2CppImageGlobalMetadata
+        {
+            public int typeStart;
+            public int exportedTypeStart;
+            public int customAttributeStart;
+            public int entryPointIndex;
+            public Il2CppImageU2019* image;
+        }
+
         private class NativeImageStruct : INativeImageStruct
         {
             public NativeImageStruct(IntPtr pointer)