wacom: Use the GDK Wayland device node path on Wayland

[ArekMiszcz]

Problem

In a Cinnamon Wayland session with a tablet connected (Wacom Intuos S 2 here), csd-wacom segfaults right after every login, and cinnamon-session gives up respawning it:

csd-wacom: segfault at 200000001 ... error 6 in libX11.so.6
#0 libX11.so.6
#1 XInternAtom
#2 xdevice_get_device_node        (plugins/common/csd-input-helper.c)
#3 get_device_path / is_opaque_tablet (plugins/wacom/csd-wacom-manager.c)
#4 migrate_tablet_settings ← device_added_cb ← add_devices

Cause

The wacom plugin does not force the X11 GDK backend, so on Wayland its GdkDevices are Wayland devices. get_device_path() still goes through gdk_x11_device_get_id() and xdevice_get_device_node(), which use the Wayland GdkDisplay as an X11 Display.

Fix

• For a Wayland device, return gdk_wayland_device_get_node_path().
• In is_opaque_tablet(), do not pass a NULL path to libwacom, and free the path afterwards (it was leaked).

The X11 code path is unchanged.

Testing

• Applies to master; the change compiles there.
• Backported to 6.4.3 on Debian 13 in a Cinnamon Wayland session with the tablet connected: csd-wacom starts, stays up and owns org.cinnamon.SettingsDaemon.Wacom. Before, it crashed within a second of starting.
• Not re-tested in an X11 session, since that path did not change.

🤖 Generated with Claude Code