API Hooking

typedef HANDLE(WINAPI *CreateFileWCallback)(
  LPCWSTR lpFileName,
  DWORD dwDesiredAccess,
  DWORD dwShareMode,
  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  DWORD dwCreationDisposition,
  DWORD dwFlagsAndAttributes,
  HANDLE hTemplateFile
  );

CreateFileWCallback OriginalCreateFileW;

HANDLE WINAPI OnCreateFileW(
  LPCWSTR lpFileName,
  DWORD dwDesiredAccess,
  DWORD dwShareMode,
  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  DWORD dwCreationDisposition,
  DWORD dwFlagsAndAttributes,
  HANDLE hTemplateFile)
{
  return OriginalCreateFileW(
    lpFileName, 
    dwDesiredAccess,
    dwShareMode,
    lpSecurityAttributes,
    dwCreationDisposition,
    dwFlagsAndAttributes,
    hTemplateFile);
}

#pragma managed
using namespace System;

namespace AxoCoverRunnerNative {

	public ref class FileRemapper
	{
    static FileRemapper()
    {
      //Locate function address to redirect
      auto moduleHandle = GetModuleHandle(L"Kernel32.dll");
      auto procAddress = GetProcAddress(moduleHandle, "CreateFileW");
      std::cout << procAddress;
      //Prepare unconditional jump opcodes
      const int jmpLength = 6;
      BYTE jmpOpcodes[jmpLength] = { 0xE9, 0x90, 0x90, 0x90, 0x90, 0xC3 };
      auto jmpDistance = (DWORD)OnCreateFileW - (DWORD)procAddress - jmpLength + 1;
      
      //Unlock original method for reading and writing
      DWORD procProtectionMode, tempProtectionMode;
      VirtualProtect((LPVOID)procAddress, jmpLength, PAGE_EXECUTE_READWRITE, &procProtectionMode);

      //Back-up original opcodes
      const int backupLength = jmpLength;
      BYTE* backupOpcodes = new BYTE[backupLength + jmpLength];
      CopyMemory(backupOpcodes, procAddress, backupLength);
      CopyMemory(backupOpcodes + backupLength, jmpOpcodes, jmpLength);
      auto backDistance = (DWORD)procAddress - (DWORD)backupOpcodes - jmpLength + 1;
      CopyMemory(backupOpcodes + backupLength + 1, &backDistance, sizeof(backDistance));
      VirtualProtect((LPVOID)backupOpcodes, backupLength + jmpLength, PAGE_EXECUTE_READWRITE, &tempProtectionMode);
      OriginalCreateFileW = (CreateFileWCallback)backupOpcodes;
      
      //Override original opcodes with unconditional jump to callback
      CopyMemory(&jmpOpcodes[1], &jmpDistance, sizeof(jmpDistance));
      CopyMemory(procAddress, jmpOpcodes, jmpLength);
      
      //Restore memory protection
      VirtualProtect((LPVOID)procAddress, jmpLength, procProtectionMode, &tempProtectionMode);
    }

    
	};
}