如何修补 delphi 类的私有方法? [英] How I can patch a private method of a delphi class?

问题描述

我已阅读这些问题和答案

I have read these questions and answers

如何改变实现(绕道)一个外部声明的函数

delphi 中的补丁例程调用

但我不知道如何修补位于另一个单元中的类的私有方法.

but i can't figere out how patch a private method of a class located in anoher unit.

检查此示例我想修补 Bar 过程.

Check this sample I want to patch the Bar procedure.

Unit ThidParty;
Interface
   Type
      TFoo =Class
        private
           procedure Bar;
       end;

我认为关键是找到获取私有方法地址的方法.

I think which the key is find a way to obtain the address of the private method.

那么，如何修补 delphi 类的私有方法?

So, How I can patch a private method of a delphi class?

推荐答案

下面概述的解决方案适用于包括 Delphi Seattle 在内的版本.您可以使用类助手来破解类:

The solution outlined below works for versions up to and including Delphi Seattle. You can use a class helper to crack the class:

Unit1

type
  TTest = class
  private
    procedure Foo;
  end;

Unit2

type
  TMyTestHelper = class helper for TTest
    function GetFooAddress: Pointer;
  end;

function TMyTestHelper.GetFooAddress: Pointer;
var
  MethodPtr: procedure of object;
begin
  MethodPtr := Self.Foo;
  Result := TMethod(MethodPtr).Code;
end;

function FooAddress: Pointer;
begin
  Result := TTest(nil).GetFooAddress;//don't need to instantiate an object
end;

将 FooAddress 的返回值传递给您的修补函数之一，您就成功了.

Pass the return value from FooAddress to one of your patching functions and you are golden.

但是，从 Delphi 10.1 Berlin 开始，这不再有效！类助手不能再访问严格保护、严格私有或私有成员.这个功能"实际上是 Embarcadero 现在在柏林修复的一个编译器错误.你运气不好.

However, starting with Delphi 10.1 Berlin, this no longer works! Class helpers can no longer access strict protected, strict private or private members. This "feature" was actually a compiler bug that Embarcadero has now fixed in Berlin. You are out of luck.

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