>I am writing something very similar right now, I am ftping 75Mb files and when they are ready I need to parse them, so when I detect a new file with the FileSystemWatcher class I wait until the file is ready by trying to open it exclusively, this is my code:
>
>

>        protected void WaitUntilFileIsReady(System.String fileName)
>        {
>            if (_eventLogger != null)
>            {
>                _eventLogger.LogEvent(string.Format("Waiting for file availability ({0} current size: {1} bytes", fileName, GetFileSize(fileName).ToString(System.Globalization.CultureInfo.InvariantCulture)), EventTypes.Wait);
>                while (!IsFileReady(fileName))
>                    System.Threading.Thread.Sleep(50);
>                _eventLogger.LogEvent(string.Format("The file {0} is available! ({1}) bytes", fileName, GetFileSize(fileName).ToString(System.Globalization.CultureInfo.InvariantCulture)), EventTypes.Available);
>            }
>        }
>
>        protected static bool IsFileReady(System.String fileName)
>        {
>            // If the file can be opened for exclusive access it means that the file
>            // is no longer locked by another process.
>            try
>            {
>                using (System.IO.FileStream inputStream = System.IO.File.Open(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.None))
>                {
>                    return (inputStream.Length >= 0); 
>                }
>            }
>            catch (System.Exception)
>            {
>                return false;
>            }
>        }
>

>
>You can ignore the _eventLogger, as that is something I use to write into Windows Event Logger (and a SQL DB) to track activity.

Yes, this is something better. I can try to open it exclusively as you do and, if it succeeds, than I would proceed.

Thanks