symbol-processor/data/out.h

#pragma once

// Check Architecture
#ifndef __arm__
#error "Symbols Are ARM-Only"
#endif

// Headers
#include <variant>
#include <functional>
#include <cstddef>
#include <string>
#include <vector>
#include <map>
#include <type_traits>
#include <cstring>

// Virtual Function Information
template <typename T>
class __Function;
template <typename T>
class __VirtualFunctionInfo {
    __VirtualFunctionInfo(T *const addr_, void *const parent_):
        addr(addr_),
        parent(parent_) {}
    [[nodiscard]] bool can_overwrite() const {
        return ((void *) *addr) != parent;
    }
    T *const addr;
    void *const parent;
    friend class __Function<std::remove_pointer_t<T>>;
};

// Thunks
typedef void *(*thunk_enabler_t)(void *target, void *thunk);
extern thunk_enabler_t thunk_enabler;

// Function Information
template <typename Ret, typename... Args>
class __Function<Ret(Args...)> {
public:
    // Types
    using ptr_type = Ret (*)(Args...);
    using type = std::function<Ret(Args...)>;
    using overwrite_type = std::function<Ret(const type &, Args...)>;

    // Normal Function
    __Function(const char *const name_, const ptr_type func_, const ptr_type thunk_):
        func(func_),
        enabled(true),
        name(name_),
        backup(func_),
        thunk(thunk_) {}
    // Virtual Function
    __Function(const char *const name_, ptr_type *const func_, void *const parent, const ptr_type thunk_):
        func(__VirtualFunctionInfo(func_, parent)),
        enabled(std::get<__VirtualFunctionInfo<ptr_type>>(func).can_overwrite()),
        name(name_),
        backup(*get_vtable_addr()),
        thunk(thunk_) {}

    // Overwrite Function
    [[nodiscard]] bool overwrite(overwrite_type target) {
        // Check If Enabled
        if (!enabled) {
            return false;
        }
        // Enable Thunk
        enable_thunk();
        // Overwrite
        type original = get_thunk_target();
        thunk_target = [original, target](Args... args) {
            return target(original, std::forward<Args>(args)...);
        };
        return true;
    }

    // Getters
    [[nodiscard]] ptr_type get(bool result_will_be_stored) {
        if (!enabled) {
            return nullptr;
        } else {
            if (result_will_be_stored) {
                enable_thunk();
            }
            if (is_virtual()) {
                return *get_vtable_addr();
            } else {
                return std::get<ptr_type>(func);
            }
        }
    }
    [[nodiscard]] ptr_type *get_vtable_addr() const {
        return std::get<__VirtualFunctionInfo<ptr_type>>(func).addr;
    }
    [[nodiscard]] type get_thunk_target() const {
        if (thunk_target) {
            return thunk_target;
        } else {
            return backup;
        }
    }

private:
    // Current Function
    std::variant<ptr_type, __VirtualFunctionInfo<ptr_type>> func;
    [[nodiscard]] bool is_virtual() const {
        return func.index() == 1;
    }

public:
    // State
    const bool enabled;
    const char *const name;

    // Backup Of Original Function Pointer
    const ptr_type backup;

private:
    // Thunk
    const ptr_type thunk;
    type thunk_target;
    bool thunk_enabled = false;
    void enable_thunk() {
        if (!thunk_enabled && enabled) {
            ptr_type real_thunk = (ptr_type) thunk_enabler((void *) backup, (void *) thunk);
            if (!is_virtual()) {
                func = real_thunk;
            }
            thunk_enabled = true;
        }
    }
};

// Shortcuts
typedef unsigned char uchar;
typedef unsigned short ushort;
typedef unsigned int uint;

// Duplicate VTable
#define RTTI_SIZE 4
template <typename T>
T *dup_vtable(T *vtable) {
    // Check
    static_assert(std::is_constructible_v<T>, "Unable To Construct VTable");
    // Get Size
    const uchar *real_vtable = (uchar *) vtable;
    real_vtable -= RTTI_SIZE;
    const size_t real_vtable_size = sizeof(T) + RTTI_SIZE;
    // Allocate
    uchar *new_vtable = (uchar *) ::operator new(real_vtable_size);
    // Copy
    memcpy(new_vtable, real_vtable, real_vtable_size);
    // Return
    new_vtable += RTTI_SIZE;
    return (T *) new_vtable;
}
#undef RTTI_SIZE

// Internal Macros
#define __PREVENT_DESTRUCTION(self) \
    ~self() = delete
#define __PREVENT_CONSTRUCTION(self) \
    self() = delete; \
    __PREVENT_DESTRUCTION(self)
#define __PREVENT_COPY(self) \
    self(const self &) = delete; \
    self &operator=(const self &) = delete

// Easily Extend Structures
template<typename T, typename = void>
struct __HasAllocate : std::false_type {};
template<typename T>
struct __HasAllocate<T, std::enable_if_t<std::is_same_v<T *, decltype(T::allocate())>>> : std::true_type {};
template <typename Super, typename Self>
class __ExtendedStruct final {
    static_assert(__HasAllocate<Super>::value, "Super Type Does Not Have A Defined Size");
    __PREVENT_DESTRUCTION(__ExtendedStruct);
    __PREVENT_COPY(__ExtendedStruct);
    alignas(Super) uchar _super[sizeof(Super)];
public:
    __ExtendedStruct() {}
    Super *super() {
        return (Super *) &_super[0];
    }
    Self data;
};
#define EXTEND_STRUCT(name, base, ...) \
    typedef __VA_ARGS__ __##name##_data; \
    typedef __ExtendedStruct<base, __##name##_data> name

// Forward Declarations
{{ forwardDeclarations }}

// Extra Headers
{{ extraHeaders }}

// Warnings
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Winvalid-offsetof"
#pragma GCC diagnostic ignored "-Wshadow"

{{ main }}

// Cleanup Warnings
#pragma GCC diagnostic pop