iTunes Update and Hidden /Users Folder: How Could Apple Blunder Like That?

05/19/2014

Last week, I reported that an Apple update had hidden the /Users folder. That’s the one at the root level of your hard disk which contains folders for each of the users on your Mac – home folders – but also a Shared folder, which some people use to transfer documents between user accounts.

For a while, us tech journalists were scratching our heads, wondering why it was hidden for some users and not everyone. But Dave Hamilton, at The Mac Observer, found out that it was caused by the iTunes 11.2 update, and not the OS X 10.9.3 update, as we had all suspected.

Apple then issued a rushed update to iTunes, fixing an issue which they described as follows:

Upon each reboot, the permissions for the /Users and /Users/Shared directories would be set to world-writable, allowing modification of these directories. This issue was addressed with improved permission handling.

Bugs happen. Strange bugs happen. This one was very strange. It only occurred if you have Find My Mac turned on, and if you had updated to iTunes 11.2. It’s great that Apple was able to fix it so quickly, but it worries me that it happened at all.

iTunes updates may contain system files; iTunes uses WebKit, Apple’s HTML rendering framework, to display pages in the iTunes Store, and it’s likely that an update to WebKit was in the iTunes update. But it’s also likely that the same new WebKit files were in the OS X 10.9.3 update, since WebKit is used by Safari, Mail and other apps. So the bug wasn’t caused by WebKit.

QuickTime frameworks are also in iTunes updates, and probably also in OS X updates released at the same time, so that probably was not the cause. But there was something specific in that iTunes update that affected a lot more than just iTunes.

Apple has large resources to test its updates. The quality assurance team for this iTunes update missed what was a very serious issue, yet I doubt they were looking at the /Users folder when checking the update. So it’s a bit of a conundrum: what could have gone wrong with this update to cause a problem that had nothing to do with iTunes?

Perhaps it was as simple as a permissions list that was malformed, that actually had nothing to do with the iTunes update. It may be that after any update like this, permissions are checked.

Bugs happen. I wish I had an answer as to exactly what in this update caused the problem. It worried a lot of people, and kept a lot of us tech journalists speculating. We could have done more productive work.