How to test if a file is fully copied in .NET

Question

I am monitoring a folder for new files and need to process them. The problem is that occasionally file opening fails, because system has not finished copying it.

Wha

Answer 1

I think the only sure way to do this is by trying to open the file exclusively and catching a specific exception. I usually hate using exceptions for normal application logic, but I'm afraid for this scenario there's no other way (at least I haven't found one yet):

public bool FileIsDone(string path)
{
  try
  {
    using (File.Open(path, FileMode.Open, FileAccess.Read, FileShare.None))
    {
    }
  }
  catch(UnauthorizedAccessException)
  {
    return false;
  }

  return true;
}