Add configuration for GNOME

.local/bin/gnome-shell-restart

@@ -0,0 +1,75 @@
+#!/bin/sh
+
+# Restart `gnome-shell` in place,
+# preserving the session and all windows
+#
+# Usually survives, but treat it like a logout:
+# save your work first, because a crash on the way down can end the session
+#
+# Debian normally forbids starting/stopping this unit by hand;
+# we allow it via a user-level drop-in (installed on first run)
+
+set -eu
+
+
+if [ "${XDG_SESSION_TYPE:-}" != "x11" ]; then
+    echo "gnome-shell-restart: only works on X11, not on ${XDG_SESSION_TYPE:-unknown}" >&2
+    exit 1
+fi
+
+
+_UNIT="org.gnome.Shell@x11.service"
+
+_DROPIN_DIR="${XDG_CONFIG_HOME:-$HOME/.config}/systemd/user/$_UNIT.d"
+_DROPIN_FILE="$_DROPIN_DIR/allow-restart.conf"
+
+
+if [ ! -f "$_DROPIN_FILE" ] || ! grep -q "SuccessExitStatus" "$_DROPIN_FILE"; then
+
+    mkdir -p "$_DROPIN_DIR"
+
+    cat > "$_DROPIN_FILE" << 'EOF'
+# Written by ~/.local/bin/gnome-shell-restart
+
+# Debian forbids starting and stopping this unit by hand
+# to protect Wayland sessions, where the shell cannot restart in place
+# => We are on X11
+[Unit]
+RefuseManualStart=no
+RefuseManualStop=no
+
+# The old shell sometimes crashes while shutting down.
+#
+# Without this line, `systemd` treats that crash as a real failure
+# and ends the whole session (i.e., logs us out)
+#
+# => We count a segfault as a normal exit
+#
+# If the shell truly keeps crashing, the start limit still ends the session
+[Service]
+SuccessExitStatus=1 SEGV
+EOF
+
+    systemctl --user daemon-reload
+fi
+
+
+# The unit allows at most 3 starts per 15 seconds
+# and one restart too many counts as a failure and logs us out
+# => Refuse to restart again too soon after the last one
+_STARTED="$(systemctl --user show -p ActiveEnterTimestamp --value "$_UNIT")"
+if [ -n "$_STARTED" ]; then
+    _AGE=$(( $(date +%s) - $(date -d "$_STARTED" +%s) ))
+    if [ "$_AGE" -lt 20 ]; then
+        echo "gnome-shell-restart: last shell start was only ${_AGE}s ago" >&2
+        echo "gnome-shell-restart: refusing to trip the start limit (wait $(( 20 - _AGE ))s)" >&2
+        exit 1
+    fi
+fi
+
+
+# Forget any earlier failure, so it does not block this restart
+systemctl --user reset-failed "$_UNIT" 2> /dev/null || true
+
+
+exec systemctl --user restart "$_UNIT"