How do I automatically delete tempfiles in c#?

Question

Hello all.
What are a good way to ensure that a tempfile is deleted if my application closes or crashes? Ideally I would like to obtain a tempfile, use it and then forget about it.

Right now I keep a list of my tempfiles and delete them with an eventhandler that triggers on Application.ApplicationExit.

Is there a better way?

Answer 1

Its nice to see that you want to be responsible, but if the files aren't huge (>50MB) you would be in line with everyone (MS included) in leaving them in the temp directory. Disk space is abundant.

As csl posted, the GetTempPath is the way to go. Users who are short on space will be able to run disk cleanup and your files (along with everyone else's) will be cleaned up.

Answer 2

Nothing is guaranteed if the process is killed prematurely, however, I use "using" to do this..

using System;
using System.IO;
sealed class TempFile : IDisposable
{
    string path;
    public TempFile() : this(System.IO.Path.GetTempFileName()) { }

    public TempFile(string path)
    {
        if (string.IsNullOrEmpty(path)) throw new ArgumentNullException("path");
        this.path = path;
    }
    public string Path
    {
        get
        {
            if (path == null) throw new ObjectDisposedException(GetType().Name);
            return path;
        }
    }
    ~TempFile() { Dispose(false); }
    public void Dispose() { Dispose(true); }
    private void Dispose(bool disposing)
    {
        if (disposing)
        {
            GC.SuppressFinalize(this);                
        }
        if (path != null)
        {
            try { File.Delete(path); }
            catch { } // best effort
            path = null;
        }
    }
}
static class Program
{
    static void Main()
    {
        string path;
        using (var tmp = new TempFile())
        {
            path = tmp.Path;
            Console.WriteLine(File.Exists(path));
        }
        Console.WriteLine(File.Exists(path));
    }
}

Now when the TempFile is disposed or garbage-collected the file is deleted (if possible). You could obviously use this as tightly-scoped as you like, or in a collection somewhere.

Answer 3

You could P/Invoke CreateFile and pass the FILE_FLAG_DELETE_ON_CLOSE flag. This tells Windows to delete the file once all handles are closed. See also: Win32 CreateFile docs.

Answer 4

You could launch a thread on startup that will delete files that exist when they "shouldn't" to recover from your crash.