LSPlant/lsplant/src/main/jni/include/utils/hook_helper.hpp

#pragma once

#include <concepts>

#include "lsplant.hpp"
#include "jni_helper.hpp"

#define CONCATENATE(a, b) a##b

#define CREATE_HOOK_STUB_ENTRY(SYM, RET, FUNC, PARAMS, DEF)                                        \
    inline static struct : public lsplant::Hooker<RET PARAMS, decltype(CONCATENATE(SYM, _tstr))>{  \
                               inline static RET replace PARAMS DEF} FUNC

#define CREATE_MEM_HOOK_STUB_ENTRY(SYM, RET, FUNC, PARAMS, DEF)                                    \
    inline static struct : public lsplant::MemHooker<RET PARAMS,                                   \
                                                     decltype(CONCATENATE(SYM, _tstr))>{           \
                               inline static RET replace PARAMS DEF} FUNC

#define RETRIEVE_FUNC_SYMBOL(name, ...)                                                            \
    (name##Sym = reinterpret_cast<name##Type>(lsplant::Dlsym(handler, __VA_ARGS__)))

#define RETRIEVE_MEM_FUNC_SYMBOL(name, ...)                                                        \
    (name##Sym = reinterpret_cast<name##Type::FunType>(lsplant::Dlsym(handler, __VA_ARGS__)))

#define RETRIEVE_FIELD_SYMBOL(name, ...)                                                           \
    (name = reinterpret_cast<decltype(name)>(lsplant::Dlsym(handler, __VA_ARGS__)))

#define CREATE_FUNC_SYMBOL_ENTRY(ret, func, ...)                                                   \
    typedef ret (*func##Type)(__VA_ARGS__);                                                        \
    inline static ret (*func##Sym)(__VA_ARGS__);                                                   \
    inline static ret func(__VA_ARGS__)

#define CREATE_MEM_FUNC_SYMBOL_ENTRY(ret, func, thiz, ...)                                         \
    using func##Type = lsplant::MemberFunction<ret(__VA_ARGS__)>;                                  \
    inline static func##Type func##Sym;                                                            \
    inline static ret func(thiz, ##__VA_ARGS__)

namespace lsplant {

using HookHandler = InitInfo;

template <char... chars>
struct tstring : public std::integer_sequence<char, chars...> {
    inline constexpr static const char *c_str() { return str_; }

    inline constexpr operator std::string_view() const { return {c_str(), sizeof...(chars)}; }

private:
    inline static constexpr char str_[]{chars..., '\0'};
};

template <typename T, T... chars>
inline constexpr tstring<chars...> operator""_tstr() {
    return {};
}

template <char... as, char... bs>
inline constexpr tstring<as..., bs...> operator+(const tstring<as...> &, const tstring<bs...> &) {
    return {};
}

template <char... as>
inline constexpr auto operator+(const std::string &a, const tstring<as...> &) {
    char b[]{as..., '\0'};
    return a + b;
}

template <char... as>
inline constexpr auto operator+(const tstring<as...> &, const std::string &b) {
    char a[]{as..., '\0'};
    return a + b;
}

inline void *Dlsym(const HookHandler &handle, const char *name) {
    return handle.art_symbol_resolver(name);
}

template <typename Class, typename Return, typename T, typename... Args>
requires(std::is_same_v<T, void> ||
         std::is_same_v<Class, T>) inline static auto memfun_cast(Return (*func)(T *, Args...)) {
    union {
        Return (Class::*f)(Args...);

        struct {
            decltype(func) p;
            std::ptrdiff_t adj;
        } data;
    } u{.data = {func, 0}};
    static_assert(sizeof(u.f) == sizeof(u.data), "Try different T");
    return u.f;
}

template <std::same_as<void> T, typename Return, typename... Args>
inline auto memfun_cast(Return (*func)(T *, Args...)) {
    return memfun_cast<T>(func);
}

template <typename, typename = void>
class MemberFunction;

template <typename This, typename Return, typename... Args>
class MemberFunction<Return(Args...), This> {
    using SelfType = MemberFunction<Return(This *, Args...), This>;
    using ThisType = std::conditional_t<std::is_same_v<This, void>, SelfType, This>;
    using MemFunType = Return (ThisType::*)(Args...);

public:
    using FunType = Return (*)(This *, Args...);

private:
    MemFunType f_ = nullptr;

public:
    MemberFunction() = default;

    MemberFunction(FunType f) : f_(memfun_cast<ThisType>(f)) {}

    MemberFunction(MemFunType f) : f_(f) {}

    Return operator()(This *thiz, Args... args) {
        return (reinterpret_cast<ThisType *>(thiz)->*f_)(std::forward<Args>(args)...);
    }

    inline operator bool() { return f_ != nullptr; }
};

// deduction guide
template <typename This, typename Return, typename... Args>
MemberFunction(Return (*f)(This *, Args...)) -> MemberFunction<Return(Args...), This>;

template <typename This, typename Return, typename... Args>
MemberFunction(Return (This::*f)(Args...)) -> MemberFunction<Return(Args...), This>;

template <typename, typename>
struct Hooker;

template <typename Ret, typename... Args, char... cs>
struct Hooker<Ret(Args...), tstring<cs...>> {
    inline static Ret (*backup)(Args...) = nullptr;

    inline static constexpr std::string_view sym = tstring<cs...>{};
};

template <typename, typename>
struct MemHooker;
template <typename Ret, typename This, typename... Args, char... cs>
struct MemHooker<Ret(This, Args...), tstring<cs...>> {
    inline static MemberFunction<Ret(Args...)> backup;
    inline static constexpr std::string_view sym = tstring<cs...>{};
};

template <typename T>
concept HookerType = requires(T a) {
    a.backup;
    a.replace;
};

template <HookerType T>
inline static bool HookSymNoHandle(const HookHandler &handler, void *original, T &arg) {
    if (original) {
        if constexpr (is_instance_v<decltype(arg.backup), MemberFunction>) {
            void *backup = handler.inline_hooker(original, reinterpret_cast<void *>(arg.replace));
            arg.backup = reinterpret_cast<typename decltype(arg.backup)::FunType>(backup);
        } else {
            arg.backup = reinterpret_cast<decltype(arg.backup)>(
                handler.inline_hooker(original, reinterpret_cast<void *>(arg.replace)));
        }
        return true;
    } else {
        return false;
    }
}

template <HookerType T>
inline static bool HookSym(const HookHandler &handler, T &arg) {
    auto original = handler.art_symbol_resolver(arg.sym);
    return HookSymNoHandle(handler, original, arg);
}

template <HookerType T, HookerType... Args>
inline static bool HookSyms(const HookHandler &handle, T &first, Args &...rest) {
    if (!(HookSym(handle, first) || ... || HookSym(handle, rest))) {
        __android_log_print(ANDROID_LOG_ERROR,
#ifdef LOG_TAG
                            LOG_TAG,
#else
                            "HookHelper",
#endif
                            "Hook Fails: %*s", static_cast<int>(first.sym.size()),
                            first.sym.data());
        return false;
    }
    return true;
}

}  // namespace lsplant