Exception generated from destination of a call

Question

I wrote this code:

    AssemblyName assemblyName = new AssemblyName("SamAsm");
    AssemblyBuilder assemblyBuilder =      Thread.GetDomain().DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
    TypeBuilder typeBuilder = assemblyBuilder.DefineDynamicModule("SamAsm.exe").DefineType("SamAsmType", TypeAttributes.Public);
    MethodBuilder methodBuilder1 = typeBuilder.DefineMethod("Main", MethodAttributes.Static | MethodAttributes.Public, typeof(void), new Type[] { typeof(string) });
    ILGenerator gen = methodBuilder1.GetILGenerator();
    FieldInfo field1 = typeof(Form1).GetField("TextBox1", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);

    MethodInfo method2 = typeof(Control).GetProperty("Text", BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).GetGetMethod();
    MethodInfo method3 = typeof(String).GetMethod(
        "op_Equality",
        BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic,
        null,
        new Type[]
        {
            typeof(String),
            typeof(String)
        },
        null
    );
    MethodInfo method4 = typeof(MessageBox).GetMethod(
        "Show",
        BindingFlags.Static | BindingFlags.Public | BindingFlags.NonPublic,
        null,
        new Type[]
        {
            typeof(String)
        },
        null
    );

    LocalBuilder a = gen.DeclareLocal(typeof(Boolean));

    System.Reflection.Emit.Label label42 = gen.DefineLabel();

    gen.Emit(OpCodes.Nop);
    gen.Emit(OpCodes.Ldarg_0);
    gen.Emit(OpCodes.Ldfld, field1);
    gen.Emit(OpCodes.Callvirt, method2);
    gen.Emit(OpCodes.Ldstr, "HI");
    gen.Emit(OpCodes.Call, method3);
    gen.Emit(OpCodes.Ldc_I4_0);
    gen.Emit(OpCodes.Ceq);
    gen.Emit(OpCodes.Stloc_0);
    gen.Emit(OpCodes.Ldloc_0);
    gen.Emit(OpCodes.Brtrue_S, label42);
    gen.Emit(OpCodes.Nop);
    gen.Emit(OpCodes.Ldstr, "You cracked me");
    gen.Emit(OpCodes.Call, method4);
    gen.Emit(OpCodes.Pop);
    gen.Emit(OpCodes.Nop);
    gen.MarkLabel(label42);
    gen.Emit(OpCodes.Ret);

    typeBuilder.CreateType().GetMethod("Main").Invoke(null, new string[] { null });
    assemblyBuilder.SetEntryPoint(methodBuilder1, PEFileKinds.WindowApplication);}

When I run it stops on

typeBuilder.CreateType().GetMethod("Main").Invoke(null, new string[] { null });

With this error:

Exception generated from destination of a call.

I checked the IL code emitted, I think it is ok. What should I do to resolve this?

I just tested in in LINQPad and it works if I remove all the emitted code except the first Nop and the last Ret. So there must be a problem with the rest. — Daniel Hilgarth, Dec 12 '12 at 12:16
I really can't find the problem in the il code.. maybe can you help me? — user1872492, Dec 12 '12 at 12:27
I am sorry, I don't have much experience with IL code. Try comparing it with IL generated by the compiler if you write equivalent C# code. — Daniel Hilgarth, Dec 12 '12 at 12:29

score 1 · Answer 1 · answered Dec 12 '12 at 21:19

1

For one thing it looks like you're declaring your method to take a string argument when it should take a Form1 (based on your use of ldfld).

answered Dec 12 '12 at 21:19

kvb

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Exception generated from destination of a call

1 Answers1