问题
I'm trying to call unmanaged printf-like function using DynamicMethod. At runtime I get a
BadImageFormatException:Index not found. (Exception from HRESULT: 0x80131124)
Is this a limitation of runtime or my emited code is wrong?
public class Program
{
[DllImport("msvcrt40.dll",CallingConvention = CallingConvention.Cdecl)]
public static extern int printf(string format, __arglist);
static void Main(string[] args) {
var method = new DynamicMethod("printf", typeof(void), new Type[0], true);
var il = method.GetILGenerator();
il.Emit(OpCodes.Ldstr, " %s=%d\n");
il.Emit(OpCodes.Ldstr, "a");
il.Emit(OpCodes.Ldc_I4_0);
il.EmitCall(OpCodes.Call, typeof(Program).GetMethod("printf", BindingFlags.Public | BindingFlags.Static), new Type[] { typeof(string), typeof(int) });
il.Emit(OpCodes.Pop);
il.Emit(OpCodes.Ret);
var action = (Action)method.CreateDelegate(typeof(Action));
action.Invoke();
}
}
回答1:
While the exception is exceptionally cryptic, I guess it is thrown due to some security checks related to calling varargs method, or it may be a bug in them. What works is to provide a logically associated type or module:
var method = new DynamicMethod("printf", typeof(void), new Type[0], typeof(Program), true);
Works flawlessly then.
来源:https://stackoverflow.com/questions/29458616/calling-varargs-method-via-dynamicmethod