A claim is held by a bus connection. If that connection goes away -- the client
crashed, was killed, or never called Release -- the claim has to go with it, or
the device is AlreadyInUse for everyone until the daemon restarts. fprintd
watches the claimant's name for exactly this reason.
Found the hard way: a Claim issued from one busctl invocation, which exits the
moment it returns, left the device permanently claimed by a connection that no
longer existed. The daemon now subscribes to NameOwnerChanged for the
claimant's unique name and, when it loses its owner, cancels any running
operation and clears the claim. Release goes through the same path so the
subscription is torn down either way.
Verified with the stock client killed mid-verify under timeout: the claim
dropped, the verify cancelled, and fprintd-list worked immediately after.
Jorijn van der Graaf
32fe0ac665