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patterncppMinor

MemoryWriter Helper class

Submitted by: @import:stackexchange-codereview··
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helperclassmemorywriter

Problem

I have created this memory writer helper to ease the write into memory process and I want your suggestions regarding it. I am very new to C++ but have 6 years knowledge of .NET languages like VB and C#.

#include 

class MemoryWriter {
private:
    USHORT _currentIndex;
    LPVOID _targetAddress;
    template
    static void editMemory(DWORD address, T data)
    {
        DWORD oldProtection;
        VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, &oldProtection);
        *((T*)address) = data;
        VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, NULL);
    }
public:
    MemoryWriter(DWORD address) {
        _currentIndex = 0;
        _targetAddress = (LPVOID)address;
    }
    template
    void write(T data)
    {
        editMemory(((DWORD)_targetAddress + _currentIndex), data);
        _currentIndex += sizeof(T);
    }
    template
    void write(LPVOID address, T data)
    {
        editMemory((DWORD)address, data);
        _currentIndex = (DWORD)address;
    }
    void reset(LPVOID newAddress = NULL)
    {
        _currentIndex = 0;

        if (newAddress)
            _targetAddress = newAddress;
    }
};

Solution

A general physical layout guideline: Put all public members, functions as well as variables, first, followed by protected members, and private members at the end. You want users to see public members first, followed by protected members. Hopefully, they don't have to see private members at all.

I added white spaces around functions to make them more readable.

class MemoryWriter {

   public:

      MemoryWriter(DWORD address) {
         _currentIndex = 0;
         _targetAddress = (LPVOID)address;
      }

      template
         void write(T data)
         {
            editMemory(((DWORD)_targetAddress + _currentIndex), data);
            _currentIndex += sizeof(T);
         }

      template
         void write(LPVOID address, T data)
         {
            editMemory((DWORD)address, data);
            _currentIndex = (DWORD)address;
         }

      void reset(LPVOID newAddress = NULL)
      {
         _currentIndex = 0;

         if (newAddress)
            _targetAddress = newAddress;
      }

   protected:

   private:

      USHORT _currentIndex;
      LPVOID _targetAddress;

      template
         static void editMemory(DWORD address, T data)
         {
            DWORD oldProtection;
            VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, &oldProtection);
            *((T*)address) = data;
            VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, NULL);
         }
};

Code Snippets

class MemoryWriter {

   public:

      MemoryWriter(DWORD address) {
         _currentIndex = 0;
         _targetAddress = (LPVOID)address;
      }

      template<typename T>
         void write(T data)
         {
            editMemory<T>(((DWORD)_targetAddress + _currentIndex), data);
            _currentIndex += sizeof(T);
         }

      template<typename T>
         void write(LPVOID address, T data)
         {
            editMemory<T>((DWORD)address, data);
            _currentIndex = (DWORD)address;
         }

      void reset(LPVOID newAddress = NULL)
      {
         _currentIndex = 0;

         if (newAddress)
            _targetAddress = newAddress;
      }

   protected:

   private:

      USHORT _currentIndex;
      LPVOID _targetAddress;

      template<typename T>
         static void editMemory(DWORD address, T data)
         {
            DWORD oldProtection;
            VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, &oldProtection);
            *((T*)address) = data;
            VirtualProtect((LPVOID)address, sizeof(T), PAGE_EXECUTE_READWRITE, NULL);
         }
};

Context

StackExchange Code Review Q#79840, answer score: 2

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