gpsd.service.d: create a socket for geoclue, add comments

etc/systemd/system/gpsd.service.d/aminda-additions.conf

@@ -1,10 +1,25 @@
+# As usual this is a systemd drop-in, so I can adjust what gpsd.service does
+# without having to fight with package management.
 [Service]
 Type=exec
+# In case the file exists, I can throw my own additional options there
 EnvironmentFile=-/etc/gpsd.aminda.conf
-ExecStart=
-# PRIVACY WARNING! --listenany happily allows anyone to ask where the host is
+# Kernel module possibly required for USB GPS devices especially with Chrony?
 ExecStartPre=-/usr/sbin/modprobe pps_ldisc
-ExecStart=/usr/sbin/gpsd /dev/gps0 --listenany --nowait --foreground $AMINDAGPSD
+# Handle failure situation of the socket not going away (ExecStartPost=)
+ExecStartPre=-/usr/bin/rm -vf /var/run/gpsd-nmea.sock
+# Empty ExecStart= before the actual ExecStart= removes the original
+# ExecStart= line
+ExecStart=
+ExecStart=/usr/sbin/gpsd /dev/gps0 --nowait --foreground $AMINDAGPSD
+# Creating a socket for geoclue to connect to
+# Credit:  @schnell at https://gitlab.freedesktop.org/geoclue/geoclue/-/issues/145#note_1772702
+ExecStartPost=/bin/sh -c "(sleep 5 && gpspipe --nmea | ( read; read; read; cat )  | ncat --verbose --keep-open --listen --unixsock /var/run/gpsd-nmea.sock&)"
+# In case of clean shutdown, remove the socket for restart
+ExecStopPost=-/usr/bin/rm -vf /var/run/gpsd-nmea.sock
+# Missing from the original unit, will reconnect all GPS says man gpsd
 ExecReload=/usr/bin/killall -HUP gpsd
+# Avoiding systemd considering the unit as failed.
 Restart=always
 RestartSec=5s
+# vim: filetype=systemd