/***************************************************Project Mutator****************************************************/
//-*-c++-*-
/*first line intentionally left blank.*/
/*loads the objects into executable memory and registers them with lua.*/
/*Copyright (C) 2017 Farzad Sadeghi

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.*/
/**********************************************************************************************************************/
#include <iostream>
#include <tuple>
#include <vector>
#include <cstdint>
#include <cstdarg>
#include <cstring>
#include <sys/mman.h>
#include "lua-5.3.4/src/lua.hpp"
/**********************************************************************************************************************/
#ifndef EXECUTIONER_H
#define EXECUTIONER_H
/**********************************************************************************************************************/
namespace {
  using XObject = void(*)(void);
  constexpr int MEMORY_SIZE = 32768;
  std::vector<uint8_t> memory(MEMORY_SIZE, 0);

  void* alloc_writeable_memory(size_t _size) {
    void* ptr = mmap(0, _size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
    if (ptr == (void*)-1) {
      perror("could not allocate virtual memory.");
      return nullptr;
    }
    return ptr;
  }

  int make_mem_executable(void* _mem, size_t _size) {
    if (mprotect(_mem, _size, PROT_READ | PROT_EXEC) == -1) {
      perror("could not make virtual memory executable.");
      return -1;
    }
    return 0;
  }
}

int getMemorySize(void) {return MEMORY_SIZE;}

class Executioner {
  public:
    Executioner() {}
    ~Executioner() {
      for (auto &iter : obj_mem_ptrs) {
        if (iter.first != nullptr) {
          if (munmap(iter.first, iter.second) < 0) {
            perror("could not unmap vmemory.");
          }
        }
      }
    }

    void getObjs(std::vector<std::vector<uint8_t>>& _objs) {objs = _objs;}

    void getNames(std::vector<std::string>& _names) {names = _names;}

    std::pair<void*, size_t> loadObjsInXMem(std::vector<uint8_t>& _obj_code) {
      size_t code_size = _obj_code.size();
      void* program_memory = alloc_writeable_memory(code_size);
      if (program_memory == nullptr) {
        std::cout << "could not allocate virtual memory\n";
        return std::make_pair(nullptr, 0);
      }
      memcpy(program_memory, _obj_code.data(), code_size);
      if (make_mem_executable(program_memory, code_size) < 0) {
        std::cout << "could not make vmemory executable.\n";
        return std::make_pair(nullptr, 0);
      }
      return std::make_pair(program_memory, code_size);
    }

    void loadAll(void) {
      for (auto &iter : objs) {
        this->loadObjsInXMem(iter);
      }
    }

    void emitByte(uint8_t _byte, std::vector<uint8_t>& _code) {
      _code.push_back(_byte);
    }

    void emitBytes(std::vector<uint8_t>& _bytes, std::vector<uint8_t>& _code) {
      for (auto &iter : _bytes) {this->emitByte(iter, _code);}
    }

    void registerWithLua(lua_State* _lua_State) {}

  private:
    std::vector<std::pair<void*, size_t>> obj_mem_ptrs;
    std::vector<std::vector<uint8_t>> objs;
    std::vector<std::string> names;
};
/**********************************************************************************************************************/
#endif
/**********************************************************************************************************************/
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