Get file path from an unique file identifier in windows

Question

I just read this post HERE and wondered if it is possible to get a current file path from that ID.

So if a file gets moved can I get the new file path by searching for that ID? Unfortunately I couldn't find anything about this topic.

Or is the ID only used to identify a file and can't be used to track the location ?

Thanks in advance.

// Added Code

public class WinAPI
{
    [DllImport("ntdll.dll", SetLastError = true)]
    public static extern IntPtr NtQueryInformationFile(IntPtr fileHandle, ref IO_STATUS_BLOCK IoStatusBlock, IntPtr pInfoBlock, uint length, FILE_INFORMATION_CLASS fileInformation);

    public struct IO_STATUS_BLOCK
    {
        uint status;
        ulong information;
    }
    public struct _FILE_INTERNAL_INFORMATION
    {
        public ulong IndexNumber;
    }

    // Abbreviated, there are more values than shown
    public enum FILE_INFORMATION_CLASS
    {
        FileDirectoryInformation = 1,     // 1
        FileFullDirectoryInformation,     // 2
        FileBothDirectoryInformation,     // 3
        FileBasicInformation,         // 4
        FileStandardInformation,      // 5
        FileInternalInformation      // 6
    }

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern bool GetFileInformationByHandle(IntPtr hFile, out BY_HANDLE_FILE_INFORMATION lpFileInformation);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern IntPtr OpenFileById(IntPtr hFile, FILE_ID_DESCRIPTOR lpFileID, uint dwDesiredAccess, uint dwShareMode, uint dwFlagas);

    [StructLayout(LayoutKind.Explicit)]
    public struct FILE_ID_DESCRIPTOR
    {
        [FieldOffset(0)] public uint dwSize;
        [FieldOffset(4)] public FILE_ID_TYPE type;
       // [FieldOffset(8)] public Guid guid;
        [FieldOffset(8)] public long FileReferenceNumber;
    }

    public enum FILE_ID_TYPE
    {
        FileIdType = 0,
        ObjectIdType = 1,
        ExtendedFileIdType = 2,
        MaximumFileIdType
    };

    public struct BY_HANDLE_FILE_INFORMATION
    {
        public uint FileAttributes;
        public FILETIME CreationTime;
        public FILETIME LastAccessTime;
        public FILETIME LastWriteTime;
        public uint VolumeSerialNumber;
        public uint FileSizeHigh;
        public uint FileSizeLow;
        public uint NumberOfLinks;
        public uint FileIndexHigh;
        public uint FileIndexLow;
    }
}

public class File_Handle
{

    public ulong Get_Index()
    {
        WinAPI.BY_HANDLE_FILE_INFORMATION objectFileInfo = new WinAPI.BY_HANDLE_FILE_INFORMATION();

        FileInfo fi = new FileInfo(@"D:\Test\Testfile.txt");
        FileStream fs = fi.Open(FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

        WinAPI.GetFileInformationByHandle(fs.Handle, out objectFileInfo);

        fs.Close();

        ulong fileIndex = ((ulong)objectFileInfo.FileIndexHigh << 32) + (ulong)objectFileInfo.FileIndexLow;

        return fileIndex;
    }

    public string Retrieve_File(ulong Index)
    {
        // WinAPI.BY_HANDLE_FILE_INFORMATION objectFileInfo = new WinAPI.BY_HANDLE_FILE_INFORMATION();
        // WinAPI.FILE_ID_DESCRIPTOR Descriptor = new WinAPI.FILE_ID_DESCRIPTOR { dwSize = sizeof(uint) + sizeof(WinAPI.FILE_ID_TYPE) + sizeof(long), type = WinAPI.FILE_ID_TYPE.FileIdType, FileReferenceNumber = (long)Index };
        WinAPI.FILE_ID_DESCRIPTOR Descriptor = new WinAPI.FILE_ID_DESCRIPTOR { dwSize = 100, type = WinAPI.FILE_ID_TYPE.FileIdType, FileReferenceNumber = (long)Index };

        FileInfo fi = new FileInfo(@"D:\Test\TestfileRef.txt");
        FileStream fs = fi.Open(FileMode.Open, FileAccess.Read, FileShare.ReadWrite);

        //FileStream wf = new FileStream(WinAPI.OpenFileById(fs.Handle, Descriptor, 0, 4, 0x08000000), FileAccess.ReadWrite);
        FileStream wf = new FileStream(WinAPI.OpenFileById(fs.Handle, Descriptor, 0, 0, 0x08000000), FileAccess.ReadWrite);

        WinAPI.BY_HANDLE_FILE_INFORMATION objectFileInfo = new WinAPI.BY_HANDLE_FILE_INFORMATION();
        WinAPI.GetFileInformationByHandle(wf.Handle, out objectFileInfo);
        fs.Close();

        wf.Close();

        return "Dummy";

    }
}

Answer 1

Because of hardlinks, a file can have more than one path. The File Id is only guaranteed to be stable as long as somebody has a open handle on the file but they are always stable on NTFS in practice. Defragmentation can change the Id on FAT32.

You could try GetFileInformationByHandleEx but results may vary based on the Windows version and file system.