MethodRental.SwapMethodBody(Type, Int32, IntPtr, Int32, Int32) Methode

Definition

Namespace:

System.Reflection.Emit

Assembly:

mscorlib.dll

Tauscht den Textkörper einer Methode aus.

public:
 static void SwapMethodBody(Type ^ cls, int methodtoken, IntPtr rgIL, int methodSize, int flags);

public static void SwapMethodBody(Type cls, int methodtoken, IntPtr rgIL, int methodSize, int flags);

static member SwapMethodBody : Type * int * nativeint * int * int -> unit

Public Shared Sub SwapMethodBody (cls As Type, methodtoken As Integer, rgIL As IntPtr, methodSize As Integer, flags As Integer)

Parameter

cls

Type

Die Klasse, die die Methode enthält.

methodtoken

Int32

Das Token für die Methode.

rgIL

IntPtr

nativeint

Ein Zeiger auf die Methode. Dies sollte den Methodenheader enthalten.

methodSize

Int32

Die Größe des neuen Methodentexts in Byte.

flags

Int32

Flags, die den Swapping steuern. Siehe die Definitionen der Konstanten.

Ausnahmen

ArgumentNullException

cls ist null.

NotSupportedException

Der Typ cls ist nicht abgeschlossen.

ArgumentException

methodSize ist kleiner als ein oder mehr als 4128767 (3effff hex).

Beispiele

Im folgenden Beispiel wird veranschaulicht, wie ein Methodentext für einen neuen Text ausgetauscht wird. Außerdem wird veranschaulicht, wie Sie ein Methodentoken für eine vorhandene Methode abrufen und wie Sie ein Blob mit Bytes erstellen, das den MSIL-Code (Microsoft Intermediate Language) darstellt, an SwapMethodBodyden übergeben werden soll.

using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Runtime.InteropServices;

class SwapMethodBodySample
{
    // First make a method that returns 0.
    // Then swap the method body with a body that returns 1.
    public static void Main(string [] args)
    {
    // Construct a dynamic assembly
    Guid g = Guid.NewGuid();
    AssemblyName asmname = new AssemblyName();
    asmname.Name = "tempfile" + g;
    AssemblyBuilder asmbuild = System.Threading.Thread.GetDomain().
        DefineDynamicAssembly(asmname, AssemblyBuilderAccess.Run);

    // Add a dynamic module that contains one type that has one method that
    // has no arguments.
    ModuleBuilder modbuild = asmbuild.DefineDynamicModule( "test");
        TypeBuilder tb = modbuild.DefineType( "name of the Type" );
        MethodBuilder somemethod = tb.DefineMethod
            ("My method Name",
             MethodAttributes.Public | MethodAttributes.Static,
             typeof(int),
             new Type[]{} );
    // Define the body of the method to return 0.
        ILGenerator ilg = somemethod.GetILGenerator();
    ilg.Emit(OpCodes.Ldc_I4_0);
    ilg.Emit(OpCodes.Ret);

    // Complete the type and verify that it returns 0.
    Type tbBaked = tb.CreateType();
    int res1 = (int)tbBaked.GetMethod("My method Name").Invoke( null, new Object[]{} );
    if ( res1 != 0 ) {
        Console.WriteLine( "Err_001a, should have returned 0" );
    } else {
        Console.WriteLine("Original method returned 0");
    }

    // Define a new method body that will return a 1 instead.
    Byte[] methodBytes = {
        0x03,
        0x30,
        0x0A,
        0x00,
        0x02,                // code size
        0x00,
        0x00,
        0x00,
        0x00,
        0x00,
        0x00,
        0x00,
        0x17,                // ldc_i4_1
        0x2a                // ret
    };

    // Get the token for the method whose body you are replacing.
    MethodToken somemethodToken = somemethod.GetToken();

    // Get the pointer to the method body.
        GCHandle hmem = GCHandle.Alloc((Object) methodBytes, GCHandleType.Pinned);
        IntPtr addr = hmem.AddrOfPinnedObject();
    int cbSize = methodBytes.Length;

    // Swap the old method body with the new body.
    MethodRental.SwapMethodBody(
                    tbBaked,
                    somemethodToken.Token,
                    addr,
                    cbSize,
                    MethodRental.JitImmediate);

    // Verify that the modified method returns 1.
    int res2 = (int)tbBaked.GetMethod("My method Name").Invoke( null, new Object[]{} );
    if ( res2 != 1 ) {
        Console.WriteLine( "Err_001b, should have returned 1" );
    } else {
        Console.WriteLine("Swapped method body returned 1");
    }
    }
}

Imports System.Reflection
Imports System.Reflection.Emit
Imports System.Runtime.InteropServices

Class SwapMethodBodySample
    
    ' First make a method that returns 0.
    ' Then swap the method body with a body that returns 1.
    Public Shared Sub Main()
        ' Construct a dynamic assembly
        Dim g As Guid = Guid.NewGuid()
        Dim asmname As New AssemblyName()
        asmname.Name = "tempfile" + g.ToString()
        Dim asmbuild As AssemblyBuilder = _
           System.Threading.Thread.GetDomain().DefineDynamicAssembly _
           (asmname, AssemblyBuilderAccess.Run)
        
        ' Add a dynamic module that contains one type that has one method that
        ' has no arguments.
        Dim modbuild As ModuleBuilder = asmbuild.DefineDynamicModule("test")
        Dim tb As TypeBuilder = modbuild.DefineType("name of the Type")
        Dim somemethod As MethodBuilder = _
           tb.DefineMethod("My method Name", _
           MethodAttributes.Public Or(MethodAttributes.Static), _
           GetType(Integer), New Type() {})
        ' Define the body of the method to return 0.
        Dim ilg As ILGenerator = somemethod.GetILGenerator()
        ilg.Emit(OpCodes.Ldc_I4_0)
        ilg.Emit(OpCodes.Ret)
        
        ' Complete the type and verify that it returns 0.
        Dim tbBaked As Type = tb.CreateType()
        Dim res1 As Integer = _
           CInt(tbBaked.GetMethod("My method Name").Invoke _
           (Nothing, New Object() {}))
        If res1 <> 0 Then
            Console.WriteLine("Err_001a, should have returned 0")
        Else
            Console.WriteLine("Original method returned 0")
        End If
        
        ' Define a new method body that will return a 1 instead.
        Dim methodBytes As Byte() = _
        {&H3, &H30, &HA, &H0, &H2, &H0, &H0, &H0, &H0, &H0, &H0, &H0, &H17, &H2A}
        '&H2     code size
        '&H17    ldc_i4_1
        '&H2A    ret
        
        ' Get the token for the method whose body you are replacing.
        Dim somemethodToken As MethodToken = somemethod.GetToken()
        
        ' Get the pointer to the method body.
        Dim hmem As GCHandle = _
           GCHandle.Alloc(CType(methodBytes, Object), GCHandleType.Pinned)
        Dim addr As IntPtr = hmem.AddrOfPinnedObject()
        Dim cbSize As Integer = methodBytes.Length
        
        ' Swap the old method body with the new body.
        MethodRental.SwapMethodBody(tbBaked, somemethodToken.Token, addr, _
           cbSize, MethodRental.JitImmediate)
        
        ' Verify that the modified method returns 1.
        Dim res2 As Integer = _
           CInt(tbBaked.GetMethod("My method Name").Invoke _
           (Nothing, New Object() {}))
        If res2 <> 1 Then
            Console.WriteLine("Err_001b, should have returned 1")
        Else
            Console.WriteLine("Swapped method body returned 1")
        End If
    End Sub
End Class

Hinweise

Sie können diese Methode nicht verwenden, um den Textkörper einer globalen Methode zu tauschen.

Die Methode kann nur vom Client aufgerufen werden, der das dynamische Modul erstellt hat, das den Typ enthält, dessen Methodentext ausgetauscht wird.