common.h

#pragma once
#include <cstring>

typedef void* (*InstantiateInterfaceFn) ();

struct InterfaceReg
{
    InstantiateInterfaceFn m_CreateFn;
    const char *m_pName;
    InterfaceReg *m_pNext;
};

inline void**& getvtable(void* inst, size_t offset = 0)
{
    return *reinterpret_cast<void***>((size_t)inst + offset);
}

inline const void** getvtable(const void* inst, size_t offset = 0)
{
    return *reinterpret_cast<const void***>((size_t)inst + offset);
}

template<typename Fn>
inline Fn getvfunc(void* inst, size_t index, size_t offset = 0)
{
    return reinterpret_cast<Fn>(getvtable(inst, offset)[index]);
}

template <typename interface>
interface* GetInterface(const char* filename, const char* version, bool exact = false)
{
    void* library = dlopen(filename, RTLD_NOLOAD | RTLD_NOW);
    
    if (!library)
        return nullptr;
    
    void* interfaces_sym = dlsym(library, "s_pInterfaceRegs");
    
    if (!interfaces_sym)
    {
        dlclose(library);
        return nullptr;
    }
    
    dlclose(library);
    
    InterfaceReg* interfaces = *reinterpret_cast<InterfaceReg**>(interfaces_sym);
    
    InterfaceReg* cur_interface;
    
    for (cur_interface = interfaces; cur_interface; cur_interface = cur_interface->m_pNext)
    {
        if (exact)
        {
            if (strcmp(cur_interface->m_pName, version) == 0)
                return reinterpret_cast<interface*>(cur_interface->m_CreateFn());
        }
        else
        {
            if (strstr(cur_interface->m_pName, version) && strlen(cur_interface->m_pName) - 3 == strlen(version))
                return reinterpret_cast<interface*>(cur_interface->m_CreateFn());
        }
    }
    
    return nullptr;
}

inline uintptr_t GetAbsoluteAddress(uintptr_t instruction_ptr, int offset, int size)
{
    return instruction_ptr + *reinterpret_cast<uint32_t*>(instruction_ptr + offset) + size;
};

template <typename T>
T GetSymbolAddress(const char* filename, const char* symbol)
{
    void* handle = dlopen(filename, RTLD_NOW);
    T result = reinterpret_cast<T>(dlsym(handle, symbol));
    dlclose(handle);
    
    return result;
};