Detecting whether a file is locked by another process (or indeed the same process) [duplicate]

Answer 1

There is no need first to check if the file is locked and then access it, as between the check and the access some other process may still get a lock on the file. So, what you do is correct, if you succeed, do your work with the file.

Answer 2

To answer your question, it would be more efficient to write the following extension method for the FileInfo class:

      public static bool IsLocked(this FileInfo f)
    {
            try 
            {
                string fpath = f.FullName;
                FileStream fs = File.OpenWrite(fpath);
                fs.Close();        
                return false;
            }

            catch (Exception) { return true; }      
    }

Once you have created the method, you can do a quick check like this:

  FileInfo fi = new FileInfo(@"C:\4067918.TIF");
  if (!fi.IsLocked()) { //DO SOMETHING HERE; }

Answer 3

No that I am aware of, there is no call to check if the file is in use - you have to try to open it and handle the exception as you are doing. Another problem is that it is hard to distinguish between in use and no access allowed.

Answer 4

The truth is, even if you do figure out a way to check if the file is "locked" by the time you get to the next line where you open the file, something else in the OS may try to get a hold of that file, and your code to open it will fail anyway. You'll have to put a try/catch there anyway. Therefore, I say no. There isn't really a better solution.