Question

Question:

Is it posible to detect when a file, for wich a have an open FileStream, was renamed.

Case:

I am trying to monitor the logs for our application, I read from the logfiles since I do not want to interfere with the logging itself.

This works great until the file gets rolled. My application keeps reading from a renamed file without even noticing.

I tried using a FileSystemWatcher to detect the roll, but sometimes a get a lot of events, sometimes I don’t, so that’s not really a good solution (also the logfiles could reside on a network share wich could be an extra hold-back for using a FSW).

If I could find out which file(name) I have an open handle to, I could compare that to the _fileName but I don’t know how or if this can be done.

Are there any other options I could explore?

Code:

this is a simplified version of my filemonitoring class:

public class MonitorFile
{
    private String _fileName = String.Empty;
    private bool _stopMonitoring = false;

    public MonitorFile(string fileName)
    {
        _fileName = fileName;
    }

    // Simplified method
    public void StartMonitoring()
    {
        using (var reader = new StreamReader(
                    new FileStream(
                        _monitorFileName,
                        FileMode.Open,
                        FileAccess.Read,
                        FileShare.Delete | FileShare.ReadWrite)))
        {
            while (!_stopMonitoring)
            {
                Thread.Sleep(500);

                while ((line = reader.ReadLine()) != null)
                {
                    //...Do stuff with the lines
                }
            }
        }
    }
}

Answer 1

There is an MSDN example showing how you can obtain a file name from a file handle (which you have access to via the Handle property of the FileStream) using Win32 APIs, but I doubt this approach will work for files on a remote network share.

You may well be out of luck in the general case.