The file upload widget on the HTML causes your browser to send a multipart request to the server. Mutlipart requests are non-trivial to read. If you're in a servlet environment, google on "OReilly multipart reader" and find their famous example. I just used this as a guideline to implement a multipart reader in a scratch-built web server. A fun exercise if you have the time.
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi