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achivetta

62 karma · joined October 24, 2010

http://www.chivetta.org
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achivetta··on APFS filesystem format
64-bit nanosecond values are actually pretty common on Darwin already. See e.g. clock_gettime_nsec_np(3).
achivetta··on Why doesn’t the clock in the taskbar display seconds? (2003)
It might not be the memory concern it once was, but today it might very well be a power concern. Modern laptop display pipelines can save power if they don't have to redraw any of the screen: constantly updating status bar animations break that.[1]

1: https://developer.apple.com/videos/play/wwdc2013/712/ (I think the relatively short graphics section mentions this. Can't seem to find the talk that goes into it in more detail...)

achivetta··on Why does calloc exist?
There's code for it in Darwin's libmalloc, but it's not exposed as API.

reallocarray() has some difficulties as an interface, mostly inherited from realloc(). I'm a bigger fan of reallocarr(), but that's NetBSD only. We (the operating systems community) need to find a consensus here, but I'm not convinced that reallocarray() is that consensus yet.

achivetta··on Making algorithms lock-free with Read-Copy Update (RCU)
Until signal handlers get involved...
achivetta··on Apple tells U.S. judge 'impossible' to unlock new iPhones
You give the HSM the pin, it returns the key used to encrypt the data, applying the rules to that interaction with you. Emulating the HSM doesn't help since it is that phone's specific HSM with the key it knows that you need to access.
achivetta··on OS X El Capitan GM Candidate available
That won't be editable anymore. But you could disable SIP from recovery mode, make the change, then re-enable it.
achivetta··on Why DNS in OS X 10.10 is broken, and what you can do to fix it
Do you have a bug number, by chance? (If not, consider filing one at bugreporter.apple.com)
achivetta··on How Not to Write a Signal Handler
As far as "modern signal handling" goes: On OS X, you can also just create a dispatch source of type DISPATCH_SOURCE_TYPE_SIGNAL. If your code already uses dispatch, this is much easier than trying to wire up to kqueue directly.
achivetta··on Let's Talk About Beacons
Who is suggesting that users would carry beacons?
achivetta··on MiniLock – File encryption software that does more with less
I think the hesitations about passphrase being subject to brute force, rainbow table, etc. are warranted, but I have another concern:

If my passphrase gets compromised, I have to retire the keypair.

That's true of a key file with current asymmetric systems; but, presently if the passphrase of my GPG private key is compromised (e.g. by a hardware key logger), I only have to change the passphrase and ensure the old keyfiles are destroyed.

With MiniLock, if my passphrase is compromised the entire key material is compromised and I need to revoke the public key. But how do I revoke it? Do I tweet a message with the private key saying the public key is revoked? Will there be a centralized place to publish revocation messages? Efficient key revocation will be absolutely critical to this system and that's hard if the key distribution mechanism is tweets or some other ad hoc mechanism. This is one thing that PGP key servers really help with.

achivetta··on Solar plant has generated “supercritical” steam
Thinking aloud: could one build a combination fossil fuel and solar steam-powered turbine? When the sun is out, you use (supercritical) steam as they describe being able to generate. If the sun goes away, you feed the same turbine with steam generated with fossil fuels. You could use same turbine, condenser, etc but just switch the heat source (or use both) as the environmental conditions change.
achivetta··on How Apple Cheats
Amazingly, this sort of use-after-free causes compatibility problems for allocator writers even today. Imagine if you change the implementation of malloc() such that smaller allocations get their own mmap() region rather than being stuffed in with other allocations. Now any use-after-free bugs to allocations affected by the change will segfault instead of reading garbage, since the allocator would munmap the region upon free().
achivetta··on The most voted Ruby question on Stack Overflow
Is this perhaps because ruby calls it a case statement instead of a switch statement?
achivetta··on Student Solves Sol Lewitt Drawing Assignment in Pseudocode
Keep in mind: This class is part of a conservatory-style BFA program. These students are already, or will soon be, custom to public critiques. And learning how to accept public criticism, positive and negative, is explicitly a goal of many such programs.

My two cents: While I would have hated such a thing in an engineering class, I really appreciated public discussion and criticism of my work in the arts. I found that such transparency, even when painful, was hugely valuable to me as I grew as an artist.

achivetta··on NSA Officers Sometimes Spy on Love Interests
It looks like there's a few different exemptions: http://www.dol.gov/whd/regs/compliance/whdfs36.htm
achivetta··on Apple Unveils iTunes Radio
What? I'm pretty sure it's not available until the fall.
achivetta··on HTML5 vs Flash Video: Battery performance analysis
Does anyone know if either of these platforms support hardware accelerated H.264 decoding? And, do either HTML5 or Flash in these environments support using it?
achivetta··on What it’s like to die
Go watch this video: http://www.heart.org/HEARTORG/CPRAndECC/HandsOnlyCPR/Hands-O...

That's all you need to know as a lay-rescuer. And if you forget, the 911 operator will walk you through it.

( Or, if you'd rather: http://supersexycpr.com )

achivetta··on The early 2013 retina MBP 15” have faulty firmware/hardware
If you are going to post online about a problem with an Apple product, I personally believe that it's a good idea to also file a bug (http://bugreporter.apple.com) and include a bug number in your post. Doubly so if you submit it to HN.

It is possible that there are people who work at Apple that read HN and if you post a bug number one of those people might then be able to open the bug.

achivetta··on Do Not Type "File:///" in OS X
Bug number?
achivetta··on [dead]
This seems like an intentionally misleading title.

I think the many people who work in "no cameras" facilities might love the option of a camera phone with an employer's profile that makes the phone safe to bring into the facility. This isn't much different from how my employer enforces the use of a passcode when connecting an iPhone to VPN.

achivetta··on Mountain Lion seems to have addressed the memory management issues in OS X
If you mmap a file, and then access the mmap'ed region, pulling in the pages of the file from disk is considered paging the file in. Watch the output of fs_usage to see examples of this.
achivetta··on Violated: A traveler’s lost faith, a difficult lesson learned
A jar of coins and... pajamas.
achivetta··on Ask HN: Found security flaw in site, what should I do?
"Hi there, I was retyping a link to my invoice and screwed up a digit. It took to someone else's page, which seems odd. For example, my link was <link> and I accidentally typed <other link>. Not sure if this is a problem or anything, so I just wanted to bring it to your attention. I'm not sure if this is the right place to email, so please let me know that you get this."

When you make strong statements, other people often have a tendency to react strongly and defensively. I assume that the person at the other end is both competent and concerned - give them all benefits of the doubt.

If you find that isn't the case, then, and only then, you can email them and use the word "security" and talk about going public after n weeks, etc.

(I am not a lawyer.)

achivetta··on The weirdest (but working) iPhone 4 reception trick I have ever heard
I wonder, is the glass just holding the phone at the right angle for the polarity of the phone's antenna and the available signal to match up? If so, this trick wouldn't likely work places other than that restaurant.