System.IO.Win32File.Open C# (CSharp) Méthode

        public static FileStream Open(string filepath, FileMode mode)
        {
            //opened in the specified mode and path, with read/write access and not shared
            FileStream fs = null;
            uint umode = GetMode(mode);
            uint uaccess = GENERIC_READ | GENERIC_WRITE;
            uint ushare = 0;	//not shared
            if (mode == FileMode.Append)
                uaccess = FILE_APPEND_DATA;
            SafeFileHandle sh = CreateFileW(LongFileName(filepath), uaccess, ushare, IntPtr.Zero, umode, FILE_ATTRIBUTE_NORMAL, IntPtr.Zero);
            int iError = Marshal.GetLastWin32Error();
            if (/*(iError > 0 && !(mode == FileMode.Append && iError == ERROR_ALREADY_EXISTS)) || */sh.IsInvalid)
            {
                throw new Exception("Error opening file Win32 Error:" + iError);
            }
            else
            {
                fs = new FileStream(sh, FileAccess.ReadWrite);
            }

            // if opened in append mode
            if (mode == FileMode.Append)
            {
                if (!sh.IsInvalid)
                {
                    SetFilePointer(sh, 0, IntPtr.Zero, FILE_END);
                }
            }

            return fs;
        }