C# Definition:

[StructLayout( LayoutKind.Sequential, CharSet = CharSet.Unicode )]

struct FILE_LINK_INFORMATION

{

  [MarshalAs( UnmanagedType.U1 )]
  public bool ReplaceIfExists;
  public IntPtr RootDirectory;
  public uint FileNameLength;
  [MarshalAs( UnmanagedType.ByValTStr, SizeConst = MAX_PATH )]
  public string FileName;

}

Notes:

MAX_PATH = 260 on NTFS