How to hook a member function of some class in C++ ?

[zsnjuts]

I want to hook a member function of some class in C++, for example, Helper::func()

class Helper {
public:
    void func(){
        // do something here...
    }
}

But I have not found related document here. Is this possible with plthook? If I want to achieve this, what efforts do I need to make? Thanks in advance.

[kubo]

I have not tested the following. I hope it is correct.

1. Methods defined in .cpp files Possible. The second argument of plthook_replace() must be the corresponding mangled name.

   // In a header file
   class Helper {
   public:
       void func(); // declaration
   };
   

   // In .cpp file
   Helper::func() {
      // do something here...  // definition
   }
   

2. Methods defined in header files Impossible. The method definition may be inlined though plthook hooks only inter-module method calls.

   // In a header file
   class Helper {
   public:
       void func() {  // declaration
          // do something here...  // definition
       }
   }
   

3. Virtual methods Impossible. It needs another technique.

[gerryyang]

Maybe you can use a c wrapper to hook cpp function, for example.

void Foo::say_world()
{
        printf("Foo::say_world\n");
}
void say_world()
{
        Foo foo;
        foo.say_world();
}

[forunix]

Is it possible to call the original c++ member function in the hooked function using the original address without knowing the type of the C++ class?