pinentry fails with "Inappropriate ioctl for device" in graphical session

[tstarling]

On a new installation of Kubuntu I installed yubikey-agent and pcscd, and then rebooted. When I tried to use ssh, I got "agent refused operation" and the syslog had

agent 13: pin prompt: unexpected response: ERR 83918950 Inappropriate ioctl for device <Pinentry>

So it seems very similar to #150. I may have misunderstood, but I don't think the root cause is the same. I'm running ssh from a graphical session, and the error message originates from pinentry-curses.c which should not be used in this situation. Reviewing pinentry_have_display suggests that either DISPLAY should be set or it should be forwarded on the command line.

The unit file in the Debian package has WantedBy=default.target which causes it to start before X, without DISPLAY. So a sufficient workaround for my purposes is

sudo mv /etc/systemd/user/default.target.wants/yubikey-agent.service /etc/systemd/user/graphical-session.target.wants/
systemctl --user daemon-reload
systemctl --user restart yubikey-agent

Then pinentry works, at least in graphical sessions. If you wanted it to work in a non-graphical session, pinentry would have to be started with the terminal as stdin and stdout.

Debian's unit file is based on the upstream unit file which also has WantedBy=default.target, so I think this is the right place to file the bug.

Note that manually starting the service from a graphical session also works. To reproduce the bug, you have to enable the unit and then reboot or log out.