sequoia-nixbld-user-migration: halt on error

[abathur]

Addressing user feedback about a case where actions the script takes may fail without a specific permission if run over SSH.

Apologies for the noise on these, but it won't shock me if there's a little more as we scramble to be ready for Monday... :)

cc @emilazy @Enzime

Context

• macOS 15 Sequoia clobbers _nixbld1-4 users #10892
• add UID migration script for macOS Sequoia 15 #11075

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[emilazy]

LGTM in principle; is the error sufficiently clear that users will be able to reasonably figure out the fix (not using SSH / enabling Full Disk Access / whatever)?

[abathur]

LGTM in principle; is the error sufficiently clear that users will be able to reasonably figure out the fix (not using SSH / enabling Full Disk Access / whatever)?

That wasn't super clear to me from Enzime's comment, but I suspect not.

There's likely one or more additional levels of messaging or detection (and I'm open to adding those here if they get sorted out before someone merges it), but I don't personally have direct access to one of these systems to poke at in order to validate the check and behavior.

In the installer wg call this morning we discussed adding a trap here to message about the possibility of the permission issue and recommend FDA, but my qualm about doing so eagerly/broadly (without having a heuristic to target this specific problem) is that we'll end up sending people with other problems down this rabbit-hole?

Edit: my tentative thinking there was that we'll have a better idea of the normal kinds of problems in a few days (but that's no reason to wait if we have someone able to ~drive on folding in a heuristic and specific message here).

[emilazy]

Seems reasonable. This is an improvement over the status quo in any case.

[Enzime]

With adding the trap, instead of making it specific to the Full Disk Access message, I was thinking saying an error occurred, and direct users to report issues in this repo potentially.

If you did want to add a heuristic, I would look into checking if you can access /Library/Preferences/com.apple.TimeMachine.plist because I get Operation not permitted even if I’m root

$ sudo cat /Library/Preferences/com.apple.TimeMachine.plist
cat: /Library/Preferences/com.apple.TimeMachine.plist: Operation not permitted
$ ls -lah /Library/Preferences/com.apple.TimeMachine.plist
-rw-r--r--  1 root  wheel    69B Jul 20 19:13 /Library/Preferences/com.apple.TimeMachine.plist

[Enzime]

LGTM

Possibly also worth adding set -u