I may be way off the mark (and no doubt others will point that out), but it seemed that the responses you got so far weren't really responding to your question.

I feel that way too: I don't feel like I'm communicating myself clearly. I got wicked explanations of GET vs. POST and great code snippets for doing the validation that I need. So, from a purely pragmatic point of view I'm all good.

The rub is, I still don't understand why this behaviour is observed. The docs say that upload will only return undef or a valid file-handle. I find that it returns a string rather than undef if I pass it a garbage filename. That wasn't expected behaviour. And, more confusing to me, the behaviour seems to change depending on whether I GET or POST it. Not understanding this bugs me! :)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.