Ensure DynamicMethodDefinition can read from DynamicILInfo initialize…

…d methods.
Washi1337 · Oct 8, 2022 · b0b13c8 · b0b13c8
1 parent 52f2e6f
commit b0b13c8
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Showing 3 changed files with 44 additions and 7 deletions.
diff --git a/src/AsmResolver.DotNet.Dynamic/DynamicMethodDefinition.cs b/src/AsmResolver.DotNet.Dynamic/DynamicMethodDefinition.cs
@@ -69,14 +69,30 @@ private MethodSignature ResolveSig(MethodBase methodBase, ModuleDefinition modul
         /// <returns>The method body.</returns>
         private static CilMethodBody CreateDynamicMethodBody(MethodDefinition method, object dynamicMethodObj)
         {
-            if (!(method.Module is SerializedModuleDefinition module))
+            if (method.Module is not SerializedModuleDefinition module)
                 throw new ArgumentException("Method body should reference a serialized module.");
 
             var result = new CilMethodBody(method);
             dynamicMethodObj = DynamicMethodHelper.ResolveDynamicResolver(dynamicMethodObj);
 
-            //Get Runtime Fields
-            byte[] code = FieldReader.ReadField<byte[]>(dynamicMethodObj, "m_code")!;
+            // Attempt to get the code field.
+            byte[]? code = FieldReader.ReadField<byte[]>(dynamicMethodObj, "m_code");
+
+            // If it is still null, it might still be set using DynamicILInfo::SetCode.
+            // Find the code stored in the DynamicILInfo if available.
+            if (code is null
+                && FieldReader.TryReadField<MethodBase>(dynamicMethodObj, "m_method", out var methodBase)
+                && methodBase is not null
+                && FieldReader.TryReadField(methodBase, "m_DynamicILInfo", out object? dynamicILInfo)
+                && dynamicILInfo is not null)
+            {
+                code = FieldReader.ReadField<byte[]>(dynamicILInfo, "m_code");
+            }
+
+            if (code is null)
+                throw new InvalidOperationException("Dynamic method does not have a CIL code stream.");
+
+            // Get remaining fields.
             object scope = FieldReader.ReadField<object>(dynamicMethodObj, "m_scope")!;
             var tokenList = FieldReader.ReadField<List<object?>>(scope, "m_tokens")!;
             byte[] localSig = FieldReader.ReadField<byte[]>(dynamicMethodObj, "m_localSignature")!;

diff --git a/src/AsmResolver.DotNet.Dynamic/DynamicMethodHelper.cs b/src/AsmResolver.DotNet.Dynamic/DynamicMethodHelper.cs
@@ -108,7 +108,7 @@ private static void InterpretEHInfo(CilMethodBody methodBody, ReferenceImporter
             for (int i = 0; i < FieldReader.ReadField<int>(ehInfo, "m_currentCatch"); i++)
             {
                 // Get ExceptionHandlerInfo Field Values
-                var endFinally = FieldReader.ReadField<int>(ehInfo, "m_endFinally");
+                int endFinally = FieldReader.ReadField<int>(ehInfo, "m_endFinally");
                 var instructions = methodBody.Instructions;
 
                 var endFinallyLabel = endFinally >= 0
@@ -155,17 +155,21 @@ public static object ResolveDynamicResolver(object dynamicMethodObj)
 
             if (dynamicMethodObj.GetType().FullName == "System.Reflection.Emit.DynamicMethod")
             {
-                var resolver = FieldReader.ReadField<object>(dynamicMethodObj, "m_resolver");
+                object? resolver = FieldReader.ReadField<object>(dynamicMethodObj, "m_resolver");
                 if (resolver != null)
                     dynamicMethodObj = resolver;
             }
             //Create Resolver if it does not exist.
             if (dynamicMethodObj.GetType().FullName == "System.Reflection.Emit.DynamicMethod")
             {
-                var dynamicResolver = typeof(OpCode).Module.GetTypes()
+                var dynamicResolver = typeof(OpCode).Module
+                    .GetTypes()
                     .First(t => t.Name == "DynamicResolver");
 
-                var ilGenerator = dynamicMethodObj.GetType().GetRuntimeMethods().First(q => q.Name == "GetILGenerator")
+                object? ilGenerator = dynamicMethodObj
+                    .GetType()
+                    .GetRuntimeMethods()
+                    .First(q => q.Name == "GetILGenerator")
                     .Invoke(dynamicMethodObj, null);
 
                 //Create instance of dynamicResolver

diff --git a/test/AsmResolver.DotNet.Dynamic.Tests/DynamicMethodDefinitionTest.cs b/test/AsmResolver.DotNet.Dynamic.Tests/DynamicMethodDefinitionTest.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Linq;
 using System.Reflection;
 using System.Reflection.Emit;
@@ -72,5 +73,21 @@ public void RtDynamicMethod()
                 module.CorLibTypeFactory.String,
             }, dynamicMethod.CilMethodBody.LocalVariables.Select(v => v.VariableType));
         }
+
+        [Fact]
+        public void ReadDynamicMethodInitializedByDynamicILInfo()
+        {
+            var method = new DynamicMethod("Test", typeof(void), Type.EmptyTypes);
+            var info = method.GetDynamicILInfo();
+            info.SetLocalSignature(new byte[] { 0x7, 0x0 });
+            info.SetCode(new byte[] {0x2a}, 1);
+
+            var contextModule = ModuleDefinition.FromFile(typeof(DynamicMethodDefinitionTest).Assembly.Location);
+            var definition = new DynamicMethodDefinition(contextModule, method);
+
+            Assert.NotNull(definition.CilMethodBody);
+            var instruction = Assert.Single(definition.CilMethodBody.Instructions);
+            Assert.Equal(CilOpCodes.Ret, instruction.OpCode);
+        }
     }
 }