List Hard Links of a file (in C#)

Question

I want to write a program that shows the files of another drive with hard links.

I want to keep both hardlinks consistent in filename and other things, so I have to get a function/method where I can list all current hard links of a file.

For example:

I have a file C:\file.txt and a second hard link to D:\file.txt.

Then I rename D:\file.txt to D:\file_new.txt.

I now want to be able to also rename the hardlink on the C drive as well.

So I need a function which returns for D:\file_new.txt that there are the following hardlinks:

C:\file.txt
D:\file_new.txt

then I can rename the hard link on C:\ also to get D:\file_new.txt

So I need to get all hard links of a physical file. Or: All hard links of a file addressed with a hard link.

Hope somebody can help!

Edit:

Oliver noticed that hard links can't be used on different disks. thanks... So I extend the question to: What do I need? Junction Points? Symbolic Links? It should also work with files not only with folders!

Answer 1

the following code should work well (originally postet by Peter provost on PowerShell Code Repository):

using System;
using System.Collections.Generic;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using Microsoft.Win32.SafeHandles;
using FILETIME = System.Runtime.InteropServices.ComTypes.FILETIME;

namespace HardLinkEnumerator
{
   public static class Kernel32Api
   {
       [StructLayout(LayoutKind.Sequential)]
       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;
       }

       [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
       static extern SafeFileHandle CreateFile(
           string lpFileName,
           [MarshalAs(UnmanagedType.U4)] FileAccess dwDesiredAccess,
           [MarshalAs(UnmanagedType.U4)] FileShare dwShareMode,
           IntPtr lpSecurityAttributes,
           [MarshalAs(UnmanagedType.U4)] FileMode dwCreationDisposition,
           [MarshalAs(UnmanagedType.U4)] FileAttributes dwFlagsAndAttributes,
           IntPtr hTemplateFile);

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

       [DllImport("kernel32.dll", SetLastError = true)]
       [return: MarshalAs(UnmanagedType.Bool)]
       static extern bool CloseHandle(SafeHandle hObject);

       [DllImport("kernel32.dll", SetLastError=true, CharSet=CharSet.Unicode)]
       static extern IntPtr FindFirstFileNameW(
           string lpFileName,
           uint dwFlags,
           ref uint stringLength,
           StringBuilder fileName);

       [DllImport("kernel32.dll", SetLastError = true, CharSet=CharSet.Unicode)]
       static extern bool FindNextFileNameW(
           IntPtr hFindStream,
           ref uint stringLength,
           StringBuilder fileName);

       [DllImport("kernel32.dll", SetLastError = true)]
       static extern bool FindClose(IntPtr fFindHandle);

       [DllImport("kernel32.dll")]
       static extern bool GetVolumePathName(string lpszFileName,
           [Out] StringBuilder lpszVolumePathName, uint cchBufferLength);

       [DllImport("shlwapi.dll", CharSet = CharSet.Auto)]
       static extern bool PathAppend([In, Out] StringBuilder pszPath, string pszMore);

       public static int GetFileLinkCount(string filepath)
       {
           int result = 0;
           SafeFileHandle handle = CreateFile(filepath, FileAccess.Read, FileShare.Read, IntPtr.Zero, FileMode.Open, FileAttributes.Archive, IntPtr.Zero);
           BY_HANDLE_FILE_INFORMATION fileInfo = new BY_HANDLE_FILE_INFORMATION();
           if (GetFileInformationByHandle(handle, out fileInfo))
               result = (int)fileInfo.NumberOfLinks;
           CloseHandle(handle);
           return result;
       }

       public static string[] GetFileSiblingHardLinks(string filepath)
       {
           List<string> result = new List<string>();
           uint stringLength = 256;
           StringBuilder sb = new StringBuilder(256);
           GetVolumePathName(filepath, sb, stringLength);
           string volume = sb.ToString();
           sb.Length = 0; stringLength = 256;
           IntPtr findHandle = FindFirstFileNameW(filepath, 0, ref stringLength, sb);
           if (findHandle.ToInt32() != -1)
           {
               do
               {
                   StringBuilder pathSb = new StringBuilder(volume, 256);
                   PathAppend(pathSb, sb.ToString());
                   result.Add(pathSb.ToString());
                   sb.Length = 0; stringLength = 256;
               } while (FindNextFileNameW(findHandle, ref stringLength, sb));
               FindClose(findHandle);
               return result.ToArray();
           }
           return null;
       }

   }
}