How to check a path is a file or directory after it's deleted by OS?

Question

I'm using System.IO.FileSystemWatcher to monitor a directory and does things when a file or directory is modified or deleted.

The issue I have is that once a folder is deleted, the Deleted event is raised, but the argument I get is not useful enough for me to know if a directory or file is deleted.

The argument I get is a path, for example C:\Temp\a which can be a directory or a file with no extension.

I tried the followings, but they all failed to give me the correct result.

var c = Path.DirectorySeparatorChar.ToString();
var isDir = Path.GetDirectoryName(path) == path.TrimEnd(c.ToCharArray());

and

var isDir =(File.GetAttributes(path) & FileAttributes.Directory) == FileAttributes.Directory;

The folder or file would have been deleted by the time you received an event. What you could do is keep a list of all files and folders internally and match the path received from your event against that list — Tien Dinh, Dec 26 '14 at 22:10
@Saruman, if it was a directory, the base directory would still exist too. — Ray Cheng, Dec 26 '14 at 22:44

score 3 · Accepted Answer · answered Dec 26 '14 at 22:11

3

I guess you can't reliably do that.

A path to a file and a directory can be ambiguous: a directory can have an 'extension' and a file can have no extension at all.

If a file or directory exists, the OS knows what it is. When it's gone, no one knows any more.

You have to remember whether it is a file or directory before deletion, not trying to determine it afterwards.

answered Dec 26 '14 at 22:11

Patrick Hofman

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You are correct, it can be known by just looking at a string, but I hope there's a OS level command I can use for that purpose since delete is almost never really deleting anything. Else, the data recovery companies will be out of business. I tried http://stackoverflow.com/a/1395251/310767 but it gives me the wrong result. – Ray Cheng Dec 26 '14 at 22:18
You have to search the ntfs disk format to find it. Seems to much work to for something like this if you can retrieve it upfront. – Patrick Hofman Dec 26 '14 at 22:23
1

For what the OS is concerned, the path is gone, so no info is available after the deletion. – John Dec 26 '14 at 22:25
@cod: I totally agree with you. In fact, for a soft deletion, the file is moved to some system directory. So the original path should be kept somewhere, not sure if it is accessible. – Patrick Hofman Dec 26 '14 at 22:30
1

@Ray: why not have two watchers? One for files, one for directories... – Patrick Hofman Dec 26 '14 at 22:31
@PatrickHofman, how to create two watchers? They have to be able to watch sub directories and files also. – Ray Cheng Dec 26 '14 at 22:45
See the duplicate question. Use `NotifyFilter = NotifyFilters.FileName` and `DirectoryName`. – Patrick Hofman Dec 27 '14 at 09:36

Selman Genç · Answer 2 · 2014-12-26T22:18:41.847

You can store the files and directories into separate collections before starting watching. Then whenever something is deleted just check which collection holds the deleted path.

For example:

var files = Directory.GetFiles("path", "*", SearchOption.AllDirectories);
var directories = Directory.GetDirectories("path","*", SearchOption.AllDirectories);

private static void OnDeleted(object source, FileSystemEventArgs e)
{
    if(files.Contains(e.FullPath))
    {
        // it's a file
    }
    else 
    {
       // it's a directory
    }
}

score 1 · Answer 3 · edited Dec 27 '14 at 09:39

In case, you have files which have extensions and Directories which have No Extension. I will suggest to use following simple solution

private static void OnDeleted(object source, FileSystemEventArgs e)
{
  bool iSDirectory = Path.GetExtension(e.FullPath).Equals("");
  if(iSDirectory)
   {
        Console.WriteLine("Directory:{0}",e.FullPath);
   }
   else
   {
         Console.WriteLine("File:{0}",e.FullPath);
   }
}

How to check a path is a file or directory after it's deleted by OS?

3 Answers3