Hi,
In the file upload event args , or other upload file object, you can use
args.FileName to get the origin filename.
and use the
args.GetTempFilePath() to get the full path of the temp file in file system.
use Path.GetFileName(args.GetTempFilePath()) to get the filename without directory.
I suggest you move/copy the temp file to your own folder, because the files in the temp folder would be deleted when the uploader maintain it.
Regards,
Terry