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Apple Crippled Its DTrace Port
Linnen writes in to note that one of developers of Sun's open source system tracing tool, DTrace, has discovered that Apple crippled its port of the tool so that software like iTunes could not be traced. From Adam Leventhal's blog: "I let it run for a while, made iTunes do some work, and the result when I stopped the script? Nothing. The expensive DTrace invocation clearly caused iTunes to do a lot more work, but DTrace was giving me no output. Which started me thinking... did they? Surely not. They wouldn't disable DTrace for certain applications. But that's exactly what Apple's done with their DTrace implementation. The notion of true systemic tracing was a bit too egalitarian for their classist sensibilities..."
As quickly as the issue is reported, a hack comes out to resolve it. Gotta love how quickly the community can respond to these things.
Could this to help prevent circumvention of DRM?
Come on, this isn't a class struggle. It's Big Business trying to protect their intellectual property. DRM sucks, this is yet another way in which it degrades computer systems. But Apple's just being a company, and their hack to DTrace is actually good coding. Dislike their choice, sure. But there's no epic struggle for humanity here.
Apple is as much the DRM laden threat to open computing as Microsoft is. We may have circumvented this issue this time, but what about the time after that? and after that? Its a cat and mouse game Apple is going to play.
This will be a big help for me in my quest for a legion of Mac zombies
I don't care if it's 90,000 hectares. That lake was not my doing.
From the DTrace source (in an #IFDEF APPLE):
/*
* If the thread on which this probe has fired belongs to a process marked P_LNOATTACH
* then this enabling is not permitted to observe it. Move along, nothing to see here.
*/
Luckily no malicious programmer will mark their malware's process with this flag!
You of all people should know that you give up your freedom to use your software and hardware as you wish when you use proprietary software. Apple's continuous attempt to stop people from changing software on their home computers is a good example of how they feel about freedom. They only side with freedom when it is immediately beneficial.
Is "egalitarian" the Slashdot word of the day today?
Fuck me, it's like a Student Union bar in here. What next, comrades, do we storm the Winter Palace or just go and sell some copies of Socialist Worker?
If you haven't made a developer cry, you've wasted a day.
Quote:
"So Apple is explicitly preventing DTrace from examining or recording data for processes which don't permit tracing. This is antithetical to the notion of systemic tracing, antithetical to the goals of DTrace, and antithetical to the spirit of open source."
Diagnostic tool that won't look at all processes is no tool at all.
You can't talk about Wikipedia's flaws on Wikipedia
Are you kidding?
This is Slashdot where "paper or plastic" is an epic struggle directly and immediately affecting the fates of billions!
BILLIONS, I tell you! BILLIONS!
The article says, "To say that Apple has crippled DTrace on Mac OS X would be a bit alarmist..." So what is the Slashdot headline? "Apple Crippled Its DTrace Port"
Nice...
Basically profile and tick are useless since they will not fire if a thread with PT_DENY_ATTACH is on proc. Perfectly good DTrace scripts simply will not work correctly on OS X.
(Note: IANA DTrace user or developer.)
The real effects seem to be that while a process which sets this flag has control of the system, any DTrace events that fire off during this time will not be detected, as if they never occurred, regardless of whether what is being traced has anything to do with that process. It seems to break a few important(?) idioms used by DTrace users, so that the results returned are not what they should be.
The furor seems to be that this subtle breakage has gone undocumented; and although only iTunes currently uses it, that does not stop other software (including software that should not be there) from using it. That a DTrace developer discovered this, combined with that this is in all likelihood being done for no reason other than that of DRM, is what makes this notable. If I were working on DTrace, I'd probably be pissed too.
Isn't this a F/OSS program? Couldn't you just recompile an uncompromised version of the source?
Knowledge is power. Knowledge shared is power multiplied.
Together with careful use of the Evil Bit by malicious coders, we will have complete security in Apple system software.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
The /. summary and most of the /. posters seem to be missing the point of the article. (To be fair, the author wasn't too clear himself. He's done some clarification in the comments section of his article.)
Sure, it's annoying that DTrace can't "see" iTunes. But that's more of a DRM issue. Whether you agree with DRM and Apple's implementation of it or not, this DTrace feature is merely a logical extension of that issue.
The real problem though is that this feature actually does break iTunes. If DTrace probes while the iTunes application happens to be the application currently running on the CPU, the DTrace probe won't run. (It's technically a thread of iTunes' at that moment.) So not only will DTrace not show iTunes, it won't show ANY information until it happens to fire off when iTunes isn't the app running on the CPU.
It is fair to say that Apple has made a change to DTrace that has introduced a bug that they need to fix. It is possible for them to fix that bug while continuing to block using DTrace on iTunes.
It's nice that Dtrace works again. But I'm betting a lot more people use After Effects or Premiere. The QT 7.4 update which enables movie rentals from iTunes breaks any render that takes longer than 10 minutes. Thank god DRM is here to protect me from the work I need to do. Wasn't apple supposed to me the machine for media professionals?
http://blogs.adobe.com/keyframes/2008/01/dont_update_to_quicktime_74.html
I just don't see what the big deal with all of this is. Smart people don't touch ITunes, because it's just going to help feed the beast. People seem to have forgotten how Jobs ran Apple the last time he was in charge. He's merely a lot more charismatic than Gates. But they are both equally self-serving.
Thankfully there are options which involve neither company.
You obviously didn't look very hard.
And software development. Or where did you think the developers of those video editors work and test their code?
No disagreement there, but it doesn't hurt to remind people that OS X is not that. People often leave Linux for OS X, claiming that it's basically an easier-to-use Linux than Linux, you still have all your stuff, etc. And you can always ssh to a Linux server to do real work.
Why is this OK?
Don't thank God, thank a doctor!
Darwin is Apple's stuff. They made it. It is based on BSD, but the BSD license doesn't require them to release the source (does it? IANAL). It is also based on NeXTSTEP, which was acquired by Apple in the 90s.
Apple's record with open source is inconsistent. Sometimes they develop internally and release source (Darwin, Bonjour), sometimes they collaborate with open source projects and share (WebKit with KDE), sometimes they buy out someone's software (Cover Flow), sometimes they steal ideas and never credit original authors (Dashboard).
Apple has its own open source license, the Apple Public Source License, approved by OSI and the FSF. However, they also release under the Apache license as well.
I would say in general, Apple is very open source-friendly, and a lot of open source developers I know have flocked to the Mac. It's just sometimes they have some evil empire corporation actions that make us Apple users shake our heads.
Scorta futuere amo!
Yes, it's annoying - every time we examine the system we are now looking at everything except for iTunes (and possibly Spy-WaR3 ;-). But this issue is about more than just that.
I've introduced DTrace to many companies. While most people love it, some developers of closed source software are concerned about people DTracing their code. DTrace allows customers to gather proof of bugs that are embarrassing, hard to fix, or that the developers have deny existed. I've been asked many times if DTrace can be disabled for an application, usually to avoid negative publicity from the bugs that DTrace will expose. The answer has always been no. It's been great to see developers accept this reality and escelate bug fixing.
This is expected - DTrace visibility should improve overall code quality in IT. Hopefully it will also encourage employers to hire better programmers - since if customers don't use DTrace to point out embarassing bugs, then competitors may. It also erodes reasons to stay closed source - customers can use DTrace to see the code anyway.
Giving developers another option, to disable DTrace visibility, is allowing a backwards step from the future.
It is DRM'd to only run on Apple hardware. There is nothing technical that prevents it from running on any modern PC since that is indeed what Macs are now. However that won't work, hence there are groups out there that have to hack it to disable that and allow it to run on any hardware.
You can argue till your blue in the face that they need to do this, doesn't change what they are doing. If it wasn't DRM'd, it'd run fine on any hardware that met its technical requirements.
It's a real shame that you can't trace iTunes. I was all set to reverse engineer it and use the code to make my own total fucking abortion of a media player. Now I'll have to settle for grafting a horrible GUI onto Mplayer, removing most of the supported formats and making it sleep without releasing the CPU 90% of the time. If I can work out some way to reliably fuck up the contents of the user's iPod, then I doubt anyone will notice the difference.
It will be tricky to make the Windows port twice as horrible though. Maybe I can get it to punch the user in the face every ten minutes?
Then, they came for gettytab, but I did not speak out, because I was happy with Apple's default terminal configuration.
Then, they came for snort, but I was not worried about intrusion detection so I did not speak up.
Next, they came for mkdep, but I did not speak out, because the maid does all my compiling.
Sadly, when it came time for them to use killall, there was nobody left to speak up for me!
Mac haters really are drama queens, aren't they? Here, read this.
Leopard's DTrace isn't broken. Apple put in an API for a program to request that debugging & dtrace be disabled for it. Clearly it's there to keep FairPlay from being broken (too easily). Something that commercial developers could understandably want for their software, to prevent keygen hacks, etc.
The link I provide shows a simple way to get around it. Hell, debugging iTunes is directly encouraged in an Apple Technote (linked in the article).
As listed in the article I linked to, you can get around it by trapping the API call in gdb and disabling it.
Care about electronic freedom? Consider donating to the EFF!
---- They're probably not going to get into a DOJ tiff over it, though . . .
*sigh*
There are plenty of alternative sources for digital music, almost all of which will play on an iPod and be indexed by iTunes. The ones that don't are formats the market isn't beating down Apple's door to support (Ogg), or which require licensing fees (WMA). All the MP3s you've bought from Amazon play on an iPod. All the tracks you import from a CD will play on an iPod. The iTunes store is a convenience for iPod owners, not a necessity.
Besides, the standard operational definition of a monopoly is that a company can raise prices without losing sales, because consumers don't have credible alternatives. So far, Apple's behavior with regard to pricing is to fight against price increases.
There are credible alternatives to the iPod for people who want a digital music player. There are credible alternatives to the iTunes store for people who want to buy digital music. There are credible ways to get music without a digital music player. Apple has the leading products in the digital music player market, and is one of the leading outlets for digital music, but there is a big-ass difference between being a market leader and being a monopolist engaging in anticompetitive behavior, and the DOJ's attitude toward market leaders in competitive markets is "don't bother me, I have real work to do."
We never ever criticize our heroes ever.
The difference you seem to be missing here is that Steve Jobs only occasionally does a boneheaded thing like this against his fan base. Bill Gates only occasionally doesn't.
Weaselmancer
rediculous.
I call BULLSHIT.
If they're selectively telling this app NOT to log "certain types of traffic", and give no notification of such, or allow the functionality to be restored, then it's CRIPPLED.
I'm so sick of apologists telling me that stuff that's broken is broken for a good reason and that I should be glad someone deigned to allow me to hack it back to some semblance of functionality without getting sued into oblivion!
Chas - The one, the only.
THANK GOD!!!
We are more forgiving of people who aren't more chronically evil, life just is that way, get over it.
Nobody and nothing is perfect, this does NOT mean that everything imperfect, is equivalent.
Do you divorce your wife for making occasional mistakes? No, only if she is habitually and frequently bad. Are you more forgiving of a son who just occasionally screws up lightly, as opposed to one who does drugs and steals from you and ends up in jail regularly? Of course. Is every political leader who has lied at least once, just as bad as Hitler? Is somebody who beats his wife every day equally bad to somebody who once slapped his wife over 50 years of marriage?
Please, stop with this pretending that all things are equivalent. There is NO double-standard here.
The best thing to do now is to make DTrace as useless as possible until Apple removes this limitation.
Every developer reading this who cares about DTrace and wants to be able to use it for system-wide metrics should set the P_LNOATTACH flag in the next point release for their app. Apple won't like it, but if enough developers do it as a form of protest, it would effectively make DTrace/Instruments ineffective, eliminating a bullet-point feature from Leopard.
Maybe everyone knows what dtrace is. I didn't. Then I watched this: link and now I do.
http://ed.markovich.googlepages.com
Back in 2000, if you installed MacsBug on a Mac you couldn't play DVDs. When you opened the DVD Player you got an error message telling you a debugger was installed. In these pre-memory protection days, MacsBug was the only debugger low-level enough to catch a whole mess of problems. Unfortunately, MacsBug was loaded when the system booted, so the only way to play a DVD was to remove MacsBug and restart your machine.
Long time Mac developer ally Bare Bones Software (they have a great text editor) created a patch that "fixed" this limitation. AFAIK, Apple never said anything about their patch and just quietly let it exist. http://www.macobserver.com/news/00/april/000418/dvdplayerhelper.shtml
This whole message mess came about because Macrovision didn't want people disabling their protection on video-output (there were Macs you could literally plug into VCRs then), and I suspect it was also to guard the CSS "encryption."
When Blu-ray movies finally show up in Macs, this kind of thing is probably going to get a lot worse than patches to D-Trace.