geode/loader/include/Geode/utils/addresser.hpp

#pragma once

/**
 * Adapted from https://gist.github.com/altalk23/29b97969e9f0624f783b673f6c1cd279
 */

#include "../utils/casts.hpp"
#include "casts.hpp"

#include <Geode/DefaultInclude.hpp>
#include <cocos-ext.h>
#include <cstdlib>
#include <stddef.h>
#include <type_traits>
#include <concepts>

namespace geode::addresser {

    template <typename T>
    inline intptr_t getVirtual(T func);

    template <typename T>
    inline intptr_t getNonVirtual(T func);

    template <typename T, typename F>
    inline F thunkAdjust(T func, F self);

    template <typename T, typename F>
    inline F rthunkAdjust(T func, F self);

    template <class Class>
    Class* friendCreate(typename std::void_t<decltype(static_cast<Class* (*)()>(&Class::create))>*) {
        auto ret = Class::create();
        ret->retain();
        return ret;
    }

    template <class Class>
    concept HasCreate = requires() {
                            { friendCreate<Class>(nullptr) } -> std::same_as<Class*>;
                        };

    class GEODE_DLL Addresser final {
        template <char C>
        struct SingleInheritance {
            virtual ~SingleInheritance() {}
        };

        struct MultipleInheritance : SingleInheritance<'L'>, SingleInheritance<'F'> {
            virtual ~MultipleInheritance() {}
        };

        static MultipleInheritance* instance();

        template <typename R, typename T, typename... Ps>
        static ptrdiff_t indexOf(R (T::*func)(Ps...)) {
            using method_t = ptrdiff_t (T::*)();
            return (reinterpret_cast<T*>(instance())->*reinterpret_cast<method_t>(func))();
        }

        template <typename R, typename T, typename... Ps>
        static ptrdiff_t indexOf(R (T::*func)(Ps...) const) {
            return indexOf(reinterpret_cast<R (T::*)(Ps...)>(func));
        }

        template <typename T>
        static ptrdiff_t thunkOf(T ptr) {
            // msvc
            if (sizeof(T) == sizeof(ptrdiff_t)) return 0;

            // all
            auto thunk = *(reinterpret_cast<ptrdiff_t*>(&ptr) + 1);

            // arm
            if (thunk & 1) thunk >>= 1;
            return thunk;
        }

        // I gave up
        // template <HasCreate Class>
        // static Class* generateInstance(Class*) {
        //     return friendCreate<Class>(nullptr);
        // }

        // I extra gave up
        template <class = void>
        static cocos2d::extension::CCScrollView* generateInstance(cocos2d::extension::CCScrollView*) {
            return cocos2d::extension::CCScrollView::create({0.0f, 0.0f}, cocos2d::CCLayer::create());
        }

        template <class = void>
        static cocos2d::CCFileUtils* generateInstance(cocos2d::CCFileUtils*) {
            return cocos2d::CCFileUtils::sharedFileUtils();
        }

        template <class Class>
        static Class* generateInstance(Class*) {
            if constexpr (std::is_abstract_v<Class>) {
                // Cant construct abstract classes, so fail early
                return nullptr;
            } else {
                // Create a random memory block with the size of Class
                // Assign a pointer to that block and cast it to type Class*
                uint8_t dum[sizeof(Class)]{};
                auto ptr = reinterpret_cast<Class*>(dum);
                // Now you have a object of Class that actually isn't an object of Class and is just a
                // random memory But C++ doesn't know that of course So now you can copy an object
                // that wasn't there in the first place
                // ((oh also get the offsets of the virtual tables))
                auto ins = new Class(*ptr);
                // this is how the first human was made
                return ins;
            }
        }

        template <class Class>
        static Class* cachedInstance() {
            static auto ret = generateInstance(static_cast<Class*>(nullptr));
            return ret;
        }

        /**
         * Specialized functionss
         */
        template <typename R, typename T, typename... Ps>
        static intptr_t addressOfVirtual(R (T::*func)(Ps...)) {
            using geode::cast::reference_cast;

            auto ins = cachedInstance<T>();
            // generateInstance will return nullptr on most abstract classes,
            // so dont bother getting the address
            if (ins == nullptr) {
                return 0;
            }
            auto index = indexOf(func);
            auto thunk = thunkOf(func);

            // [[this + thunk] + offset] is the function we want
            auto address = *reinterpret_cast<intptr_t*>(*reinterpret_cast<intptr_t*>(reinterpret_cast<intptr_t>(ins) + thunk) + index);

            address = followThunkFunction(address);

            return address;
        }

        template <typename R, typename T, typename... Ps>
        static intptr_t addressOfVirtual(R (T::*func)(Ps...) const) {
            return addressOfVirtual(reinterpret_cast<R (T::*)(Ps...)>(func));
        }

        template <typename R, typename T, typename... Ps>
        static intptr_t addressOfNonVirtual(R (T::*func)(Ps...) const) {
            return addressOfNonVirtual(reinterpret_cast<R (T::*)(Ps...)>(func));
        }

        static intptr_t followThunkFunction(intptr_t address);

        template <typename R, typename T, typename... Ps>
        static intptr_t addressOfNonVirtual(R (T::*func)(Ps...)) {
            return followThunkFunction(geode::cast::reference_cast<intptr_t>(func));
        }

        template <typename R, typename... Ps>
        static intptr_t addressOfNonVirtual(R (*func)(Ps...)) {
            return followThunkFunction(geode::cast::reference_cast<intptr_t>(func));
        }

        template <typename T>
        friend intptr_t getVirtual(T func);

        template <typename T>
        friend intptr_t getNonVirtual(T func);

        template <typename T, typename F>
        friend F thunkAdjust(T func, F self);

        template <typename T, typename F>
        friend F rthunkAdjust(T func, F self);
    };

#ifdef GEODE_ADDRESSER_TEST
    template <typename T>
    inline intptr_t getVirtual(T func) {
        return Addresser::addressOfVirtual(func);
    }

    template <typename T>
    inline intptr_t getNonVirtual(T func) {
        return Addresser::addressOfNonVirtual(func);
    }
#else
    template <typename T>
    inline intptr_t getVirtual(T func) {
        // log::debug(
        //     "Get virtual function address from {}",
        //     utils::intToHex(geode::cast::reference_cast<intptr_t>(func))
        // );
        auto addr = Addresser::addressOfVirtual(func);
        // log::debug("The address is: {}", utils::intToHex(addr));
        return addr;
    }

    template <typename T>
    inline intptr_t getNonVirtual(T func) {
        // log::debug(
        //     "Get non-virtual function address from {}",
        //     utils::intToHex(geode::cast::reference_cast<intptr_t>(func))
        // );
        auto addr = Addresser::addressOfNonVirtual(func);
        // log::debug("The address is: {}", utils::intToHex(addr));
        return addr;
    }

    template <typename T, typename F>
    inline F thunkAdjust(T func, F self) {
        // do NOT delete the line below.
        // doing so breaks thunk adjusting on windows.
        // why? bruh idk
        auto _ = *geode::cast::template union_cast<ptrdiff_t*>(&func);
        return (F)((intptr_t)self + Addresser::thunkOf(func));
    }

    template <typename T, typename F>
    inline F rthunkAdjust(T func, F self) {
        // do NOT delete the line below.
        // doing so breaks thunk adjusting on windows.
        // why? bruh idk
        auto _ = *geode::cast::template union_cast<ptrdiff_t*>(&func);
        return (F)((intptr_t)self - Addresser::thunkOf(func));
    }
#endif
}