Create vtable structs with function pointers about ghidra-cpp-class-analyzer HOT 10 CLOSED

Currently it's very tedious to create the structs representing the vtable in Ghidra. It would be convenient if this extension could create those structs and function pointer types based off of the signatures of the destinations.

It does. You can get to it quickly by right-clicking on the type in the "ClassTypeInfo Tree" and selecting "Edit Data Type". From there just right click on the _vptr component and choose "Edit Component".

The creation should occur when the corresponding c++ class analyzer is run.

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Hmmm... I seem to not have those things. I have "Edit" but the structure that I get is empty. Is there an example binary that is known to work well with this extension that I can compare with?

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Hmmm... I seem to not have those things. I have "Edit" but the structure that I get is empty. Is there an example binary that is known to work well with this extension that I can compare with?

It is "Edit". I was going off memory.

If the Structure is empty then the cause would be one of 3 things:

• No vtable
• Vtable wasn't found
• Some other bug

If you are certain that there is a vtable for the class in question then this would definitely require further investigation.

A class which has a located vtable should have a "Goto vtable" option available on right clicking on it in the tree.

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As a sanity check you can always run it on libstdc++.so and then check the iostream classes.

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Ok, I think I have the analyzers running properly on this test case:

struct Bar {
        virtual int a(int x) = 0;
        virtual int b(double x, double y) = 0;
        virtual int get() = 0;
};

struct Foo : public Bar {
        int a(int ax) override {
                x = ax;
                return x;
        }
        int b(double ax, double ay) override {
                x = ax;
                y = ay;
                return y;
        }
        virtual int get() {
                return y;
        }
        int x;
        int y;
};

int main() {
        Bar* b = new Foo;
        b->a(4);
        b->b(6, 7);
        return b->get();
}

Foo and Bar both show up in the ClassTypeInfo Tree and both have "Goto Vtable". However the vtable* _vptr member of Bar is empty. I'd like it to be automatically/or semi-automatically filled in with 3 function pointers that have types matching the signatures of a, b and get respectively.

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This seems like a regression. I will investigate with the provided example tomorrow. The vtable structs shouldn't be empty and should have the function signatures.

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FWIW, I built it with gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)

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I was able to reproduce this. I should have it fixed within a couple days.

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b6f24a7 should have fixed the issue

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Yep. It works for me now. Thanks!

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