Mactoy v0.6.0: Time Machine drives are protected, and no more freezes

Both changes in this release started as pull requests from @gbentz2: #12 and #13. Thank you!

What's new

Time Machine drives are locked (#13)

To macOS, a USB Time Machine drive is just another external disk, so Mactoy used to list it as something it could erase. Picking the wrong row could wipe your backups.

Now Mactoy recognises Time Machine drives:

• They're still listed, marked Time Machine backup · locked, and Mactoy won't pick one when it chooses a drive for you.
• Install, Update and Flash are blocked on them, and the Install and Flash tabs explain why.
• If you really do want to reuse an old backup drive, Unlock This Drive… lets you, after a warning that its backups will be lost. The unlock covers that one drive until you lock it again, unplug it or quit Mactoy. The erase confirmation also reminds you that the backups will be erased.
• Mactoy checks again right before writing, so a backup drive can't slip through between refreshes.

Older Time Machine drives formatted as Mac OS Extended (HFS+) aren't detected.

No more beachballs (#12)

Mactoy refreshed its disk list on the main thread every two seconds. With a busy drive attached, such as a Time Machine destination, the app could freeze for 15 to 20 seconds at a time, and clicking Install could hang it. That work now happens in the background.

The erase confirmation opens straight away and fills in how much data is on the drive a moment later. That figure is now correct for APFS-formatted drives too; before, Mactoy couldn't measure them at all.

Smaller fixes

• If refreshing the disk list keeps failing, the sidebar says the list may be out of date, instead of silently showing an old one.
• Commands that print a lot of output no longer hang. On a Mac with a very large number of volumes, this could have left the disk list empty.

Install

:::sh
# Download Mactoy-0.6.0.dmg from the release assets.
open Mactoy-0.6.0.dmg
# Drag Mactoy.app into /Applications, replacing the old version.

Apple-notarized. The way the app talks to its background helper hasn't changed, so updating doesn't ask you to approve the helper again.

How this was tested

• 167 automated tests, 23 of them new. The Time Machine lock and the output fix were each checked by putting the old behaviour back and confirming a test fails.
• The used-space figure was checked against df on APFS and exFAT disk images.
• Independent code review of both pull requests and of the follow-up work.

Not tested on a real Time Machine drive. The detection follows what diskutil reports and its documentation, but I don't have a backup drive to try it on. If yours isn't marked, please open an issue with the output of diskutil apfs list.

SHA256 of Mactoy-0.6.0.dmg is published below the release assets.