如何在非托管内存中实例化C#类?(可能的?)

我一直在尝试在非托管内存中创建类.有可能但有一个我目前无法解决的问题-您无法将对象分配给引用类型字段 -请参阅底部的编辑内容，因此您可以在您的自定义类中只有结构字段.这很邪恶:

I have been experimenting creating classes in unmanaged memory. It is possible but has a problem I am currently unable to solve - you can't assign objects to reference-type fields -see edit at the bottom-, so you can have only structure fields in your custom class. This is evil:

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

public class Voodoo<T> where T : class
{
    static readonly IntPtr tptr;
    static readonly int tsize;
    static readonly byte[] zero;

    public static T NewInUnmanagedMemory()
    {
        IntPtr handle = Marshal.AllocHGlobal(tsize);
        Marshal.Copy(zero, 0, handle, tsize);
        IntPtr ptr = handle+4;
        Marshal.WriteIntPtr(ptr, tptr);
        return GetO(ptr);
    }

    public static void FreeUnmanagedInstance(T obj)
    {
        IntPtr ptr = GetPtr(obj);
        IntPtr handle = ptr-4;
        Marshal.FreeHGlobal(handle);
    }

    delegate T GetO_d(IntPtr ptr);
    static readonly GetO_d GetO;
    delegate IntPtr GetPtr_d(T obj);
    static readonly GetPtr_d GetPtr;
    static Voodoo()
    {
        Type t = typeof(T);
        tptr = t.TypeHandle.Value;
        tsize = Marshal.ReadInt32(tptr, 4);
        zero = new byte[tsize];

        DynamicMethod m = new DynamicMethod("GetO", typeof(T), new[]{typeof(IntPtr)}, typeof(Voodoo<T>), true);
        var il = m.GetILGenerator();
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Ret);
        GetO = m.CreateDelegate(typeof(GetO_d)) as GetO_d;

        m = new DynamicMethod("GetPtr", typeof(IntPtr), new[]{typeof(T)}, typeof(Voodoo<T>), true);
        il = m.GetILGenerator();
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Ret);
        GetPtr = m.CreateDelegate(typeof(GetPtr_d)) as GetPtr_d;
    }
}

如果您担心内存泄漏，请在完成类操作后始终调用FreeUnmanagedInstance.如果您想要更复杂的解决方案，可以尝试以下方法:

If you care about memory leak, you should always call FreeUnmanagedInstance when you are done with your class. If you want more complex solution, you can try this:

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


public class ObjectHandle<T> : IDisposable where T : class
{
    bool freed;
    readonly IntPtr handle;
    readonly T value;
    readonly IntPtr tptr;

    public ObjectHandle() : this(typeof(T))
    {

    }

    public ObjectHandle(Type t)
    {
        tptr = t.TypeHandle.Value;
        int size = Marshal.ReadInt32(tptr, 4);//base instance size
        handle = Marshal.AllocHGlobal(size);
        byte[] zero = new byte[size];
        Marshal.Copy(zero, 0, handle, size);//zero memory
        IntPtr ptr = handle+4;
        Marshal.WriteIntPtr(ptr, tptr);//write type ptr
        value = GetO(ptr);//convert to reference
    }

    public T Value{
        get{
            return value;
        }
    }

    public bool Valid{
        get{
            return Marshal.ReadIntPtr(handle, 4) == tptr;
        }
    }

    public void Dispose()
    {
        if(!freed)
        {
            Marshal.FreeHGlobal(handle);
            freed = true;
            GC.SuppressFinalize(this);
        }
    }

    ~ObjectHandle()
    {
        Dispose();
    }

    delegate T GetO_d(IntPtr ptr);
    static readonly GetO_d GetO;
    static ObjectHandle()
    {
        DynamicMethod m = new DynamicMethod("GetO", typeof(T), new[]{typeof(IntPtr)}, typeof(ObjectHandle<T>), true);
        var il = m.GetILGenerator();
        il.Emit(OpCodes.Ldarg_0);
        il.Emit(OpCodes.Ret);
        GetO = m.CreateDelegate(typeof(GetO_d)) as GetO_d;
    }
}

/*Usage*/
using(var handle = new ObjectHandle<MyClass>())
{
    //do some work
}

希望它能对您有所帮助.

I hope it will help you on your path.

找到了引用类型字段的解决方案:

class MyClass
{
    private IntPtr a_ptr;
    public object a{
        get{
            return Voodoo<object>.GetO(a_ptr);
        }
        set{
            a_ptr = Voodoo<object>.GetPtr(value);
        }
    }
    public int b;
    public int c;
}

更好的解决方案.只需使用 ObjectContainer< object> 而不是 object 等.

Even better solution. Just use ObjectContainer<object> instead of object and so on.

public struct ObjectContainer<T> where T : class
{
    private readonly T val;

    public ObjectContainer(T obj)
    {
        val = obj;
    }

    public T Value{
        get{
            return val;
        }
    }

    public static implicit operator T(ObjectContainer<T> @ref)
    {
        return @ref.val;
    }

    public static implicit operator ObjectContainer<T>(T obj)
    {
        return new ObjectContainer<T>(obj);
    }

    public override string ToString()
    {
        return val.ToString();
    }

    public override int GetHashCode()
    {
        return val.GetHashCode();
    }

    public override bool Equals(object obj)
    {
        return val.Equals(obj);
    }
}