PVS-Studio warning V579 for CamStudio

LONG GetRegKey (HKEY key, LPCTSTR subkey, LPTSTR retdata)
{
  HKEY hkey;
  LONG retval = ::RegOpenKeyEx (key, subkey,
    0, KEY_QUERY_VALUE, &hkey);
  if (retval == ERROR_SUCCESS)
  {
    long datasize = MAX_PATH;
    TCHAR data[MAX_PATH];
    ::RegQueryValue (hkey, NULL, data, &datasize);
    // Cause C4996 warning, marked as deprecation candidate
    // _tcscpy (retdata, data);
    // Safe replacement
    strcpy_s(retdata, sizeof(retdata), data );
    ::RegCloseKey (hkey);
  }
  return retval;
}

It was right but unsafe. Then they made it safe but not right :)

This suspicious code was found in CamStudio project by PVS-Studio static code analyzer.
Warning message is:
V579 The strcpy_s function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the second argument. camsys.cpp 39

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/