System.IO.FileStream.GetLengthInternal C# (CSharp) Method

        private long GetLengthInternal()
        {
            Interop.Kernel32.FILE_STANDARD_INFO info = new Interop.Kernel32.FILE_STANDARD_INFO();

            if (!Interop.Kernel32.GetFileInformationByHandleEx(_fileHandle, Interop.Kernel32.FILE_INFO_BY_HANDLE_CLASS.FileStandardInfo, out info, (uint)Marshal.SizeOf<Interop.Kernel32.FILE_STANDARD_INFO>()))
                throw Win32Marshal.GetExceptionForLastWin32Error();
            long len = info.EndOfFile;
            // If we're writing near the end of the file, we must include our
            // internal buffer in our Length calculation.  Don't flush because
            // we use the length of the file in our async write method.
            if (_writePos > 0 && _filePosition + _writePos > len)
                len = _writePos + _filePosition;
            return len;
        }