The Exact Cause of the Zune Meltdown

An anonymous reader writes "The Zune 30 failure became national news when it happened just three days ago. The source code for the bad driver leaked soon after, and now, someone has come up with a very detailed explanation for where the code was bad as well as a number of solutions to deal with it. From a coding/QA standpoint, one has to wonder how this bug was missed if the quality assurance team wasn't slacking off. Worse yet: this bug affects every Windows CE device carrying this driver."

Comments

Import calendar?

[TurtleBlue]

"From a coding/QA standpoint, one has to wonder how this bug was missed if the quality assurance team wasn't slacking off."

I can't remember the last time a QA department was asked to test date functions... but then again, I can't remember the last time anyone wrote their own Leap Year calendaring calculator from scratch.

I'm sure there are a hundred reasons to do it (licensing being one of them) but really, when was the last time you didn't just import calendaring from another library and call it a day?

Please clarify to me if this is something at the hardware driver level: I honestly don't know. If this were me, my own bosses wouldn't ask "Why didn't QA catch this", as much as "why are you wasting time writing your own calendar code? And then why didn't you flag it as functionality that needed to be tested?"

Re:Import calendar?

[TurtleBlue]

Thanks - that makes a tad more sense. I see everyone running around blaming Microsoft for the code since their name is on the product, even if it was a 3rd party vendor. They certainly are still liable for all the busted Zunes, but I couldn't imagine Microsoft didn't have *some* C leap-year code sitting around that actually worked, and could be compiled for any chip they wanted.

Microsoft still has to take the hit up front, but then they'll sue or "renegotiate contracts" with the vendor that supplied the bad driver code, based on what it costs them.

I'm still shocked that the manufacturer couldn't dig up *some* free/open calendaring code that's was around pre-2004. But hey, at least we know they were honest about not ripping off some other source code and calling it their own.

Re:Import calendar?

[jc42]

[Microsoft] designed it and sell it as a unit even if parts are from other places. They have a responsibility to test it.

No, they don't. They have several decades of success selling untested software. Their customers have given them a very strong message: "We don't care about quality or reliability. We only want to buy whatever Microsoft sells. Don't tell us about something from another vendor that's higher quality; we aren't interested."

They've become a huge success. They're obviously doing what their customers want. They'd be stupid to waste good money on silly things like testing that won't increase their sales.

Or, as others here keep pointing out, Microsoft's only "responsibility" is to its shareholders. Their ongoing success has hugely rewarded their shareholders. They are obviously Doing It Right. They have no other responsibilities.

If there are signs that this fuss has a lasting effect on their profitability, they'll do something about it. But it'll probably die off in a short time, and only a few geeks (non-customers) will remember it. How many people can name even one piece of software that died on Jan 1, 2000? Customers won't remember this one, either. Most of them will never even hear about it. So Microsoft's management isn't worried about it.

And anyway, the problem is "fixed" now (for another 3.99 years). So why even bother discussing it?

(What, me cynical? ;-)

Re:Warning, Y2.1K bug.

[narcberry]

I think you missed the point.

Re:Old

[larry bagina]

Comments in the last zune slashdot story (yesterday?) were just as detailed as this "story". Maybe slashdot editors should read their own site. Or maybe I should start submitting all +5 comments for their own story.

MOD PARENT UP Re:Why write any date/time code?

[exphose]

Exactly, just goes to show the dangers in not QA'ing the whole codebase including supplied drivers. You can't trust your own code so you QA it, why should you trust your partner's code.

Re:MOD PARENT UP Re:Why write any date/time code?

[JoeMerchant]

But really, no one can be expected to QA every single line of code that's shipped through their device

All depends on the level of concern - for a music player, what the hell, it's only the company's reputation that's riding on it... (now, if the company isn't already a laughingstock, maybe this might matter.) If this were code on a Mars Surveyor mission whose failure would set back an entire program by 2 years or more - I'd be checking every line of code, everywhere, three times.

Re:Regardless of whatever code in it is faulty

[KiltedKnight]

Ever written code for an OS or device driver? You use them there... frequently... as "get me the frack out of here because of a fatal error"...

Never mind that if done properly, there is nothing wrong with using a goto statement... just make sure that you only move in one direction... ideally "down" towards the end of the function, not somewhere else in the whole program.

Re:Why write any date/time code?

[cbhacking]

Ah, thank you. This explains better why the 2nd-gen and 3rd-gen Zunes didn't suffer this problem; they were completely designed and developed in-house.

Re:Warning, Y2.1K bug.

[PIBM]

Actually, it's far from being good. In 99% of the cases you will do 3 modulos operation, in 0.75% you will do 2 modulos and in 0.25% you will do 1 modulo, for an average modulo cost of 2.9875 per run.

With the initial solution, you have 1 modulo in 75% of the cases, 2 modulo in 24% of the cases, and 3 modulo in 1% of the cases, for a total average modulo cost of 1.26 per run.

Not QA's fault

[Sleepy]

"evidence of QA.. slacking off"

These comments routinely come from two groups:

1) Software Developers
2) Joe the Plumber

Or put another way: elitism or ignorance.

If a software division is letting QA "test" all on their own, that's a recipe for disaster... and it's the head of engineering at fault.

See, software testing does not occur in a vacuum, no more than developers code without a list of requirements from Sales or Marketing.

Engineering takes takes the requirements, use that to produce an agreed upon set of specifications.

QA follows the same model... they take the software specs and derive a set of effective tests.... tests which are agreed upon by Engineering, and signed off on.

When I did QA, it was mostly for startups who lacked this kind of process. The result was QA was always 2 steps behind software that continually morphed: hardware changed, or the customer changed their mind. I'm not placing the blame on any 1 group here... I come from Support, then QA, and now develop. Startups can be rough.

But at the end of the day, not documenting and agreeing on what the product and tests should be will cost you big time.. maybe 7 out of 10 times.

Re:Warning, Y2.1K bug.

[Bozdune]

If my code's still running in 2100, our society has got way bigger problems than me not figuring leap years correctly.

Re:Let's make sure this gets installed everywhere

[neokushan]

When has Microsoft ever actually done that? Apple has released updates that DELIBERATELY bricked devices (jailbroken iphones for one), but that's ok, yet when a Microsoft device breaks due to a very obvious bug (obvious in that it's obvious it IS a bug, not obvious in that it really should have been noticed - bugs do happen in pretty much ALL software) that has a stupidly simple fix (Let it drain the battery then turn it on again), suddenly the Conspiracy theories are out in full force and they're once again branded as the most Evil Corporation on the planet? Please.

There's so much you can bash Microsoft for (legitimately), why do you feel the need to actually make shit up?

Besides, from all the reports I've read so far, Windows 7 is actually looking to be a worthy Upgrade (if you're a windows user, that is - for anyone else, your mileage may vary) and I don't just mean from Vista, I mean from XP as well.

But no, it's easier to just hate the large, monolithic, rich company than accept that sometimes shit just happens.

Re:Warning, Y2.1K bug.

[lyml]

That's just silly, readability trumps over using modulo a thousand times. Always, with no exceptions.

Re:Why is this a surprise?

[ozphx]

Lots of things use Windows CE, which is fine.

The problem is with the Freescale Semiconductor's* RTC driver. So if you aren't using that specific chip and driver then CE is unaffected.

* No, this doesn't excuse MS from proper QA.

Re:Let's make sure this gets installed everywhere

[gutter]

Ok, I'm getting sick of this claim. There is no proof that Apple has ever deliberately bricked devices. This is completely unfounded.

In fact, go back and look at the reports of iPhones breaking, and you'll see that most of them started working again with a later OS release. About the only thing that happens on upgrade with jailbroken phones these days is that they are locked again.

Re:Warning, Y2.1K bug.

[Anonymous Coward]

Yuk. Unreadable tripe. It's basically the same algorithm, implemented very poorly. Try:

def isLeapYear(year):
        return (year % 4 == 0 and (not year % 100 == 0)) or (year % 400 == 0)

Re:Warning, Y2.1K bug.

[jcr]

COBOL really shouldn't have been allowed to survive past 1990.

I disagree. I wouldn't want to write a 3D CAD program in it, but COBOL is still a fine choice when the task at hand is to account for a million monthly utility bills. The built-in BCD arithmetic is very well suited for implementing financial applications, and COBOL isn't susceptible to buffer-overflow bugs like the C-based languages are.

-jcr

Re:Let's make sure this gets installed everywhere

[db32]

First of all, this was a braindead stupid bug. Unbelievably poor implementation of what should have been a fairly simple thing leads to an infinite loop on special days. Just looking at the damned loop without actually tracing through every possibility reveals a infinite loop at first glance. This was mindbogglingly stupid.

Second...Apple didn't "deliberately brick" devices. Your bias here is unbelievable. What Apple did was fix a bug that was allowing people to jailbreak and that caused problems from jailbroken phones. They fixed a security flaw that caused something that took advantage of that security flaw to cease to function correctly. Now, personally I would like it if the iPhone didn't require jailbreaking to open it up, but fixing the flaw that allows people to break your security model is not "deliberatly bricking". WGA is deliberately bricking, where it arbitrarily decides that you are invalid and shuts you off. In both cases it is incorrect useage of the word "brick" since either device can be easily recovered. So...to recap. Apple fixed a security flaw that caused bad news for people jailbreaking. Microsoft told your computer to call home every day so they could arbitrarily decide if you were valid or not and then shut you off if you werent.

It is easier to hate the large monolitic rich company that uses illegal business practices, breaks the standards, and buys off the DoJ to avoid punishment (Go look at MS political contributions to either party before the trial...virtually nil...then the year they get busted...they contribute big bucks to both sides and walk away with a wrist slap). Trust me...big time criminals don't need cheerleaders like you to help them out. People like you are like the wife that geats her ass kicked and says "no, but he really loves me, he really is a good guy".