overlay/15fcos: upgrade bootloader for secureboot-enabled systems

kernel 6.9 won't boot on system installed prior to F39, as shim is too old.
Shim 15.8-3 reached stable on 2023-03-21, so any system using secureboot
installed before that won't be able to boot kernel 6.9

See coreos/fedora-coreos-tracker#1752
fedora-silverblue/issue-tracker#543

overlay.d/15fcos/usr/lib/systemd/system-preset/45-fcos.preset

@@ -9,3 +9,6 @@ enable coreos-check-wireless-firmwares.service
 # Strip extraneous field in aleph files to avoid bootupctl failing
 # https://github.com/coreos/fedora-coreos-tracker/issues/1724
 enable coreos-fix-aleph-file.service
+# Upgrade bootloader on Secure Boot-enabled nodes to avoid
+# https://github.com/coreos/fedora-coreos-tracker/issues/1752
+enable coreos-bootupctl-update-secureboot.service

overlay.d/15fcos/usr/lib/systemd/system/coreos-bootupctl-update-secureboot.service

@@ -0,0 +1,19 @@
+# Remove after the next barrier release
+
+[Unit]
+Description=Update Bootloader for Secure Boot-enabled Systems
+Documentation=https://github.com/coreos/fedora-coreos-tracker/issues/1752
+ConditionSecurity=uefi-secureboot
+
+# make sure to run after the aleph file is fixed
+# see https://github.com/coreos/fedora-coreos-tracker/issues/1724
+After=coreos-fix-aleph-file.service
+Requires=coreos-fix-aleph-file.service
+
+[Service]
+Type=oneshot
+ExecStart=/usr/libexec/coreos-update-bootloader
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target

overlay.d/15fcos/usr/libexec/coreos-update-bootloader

@@ -0,0 +1,27 @@
+#!/bin/bash
+set -euo pipefail
+
+# This script update the bootloader using bootupd
+# and also detect RAID-1 setups as those requires
+# extra steps
+
+if [ -e /dev/disk/by-label/EFI-SYSTEM ]; then
+    echo "Found ESP; calling 'bootupctl update'"
+    bootupctl update
+    exit
+fi
+
+# handle RAID case manually since bootupd doesn't support it
+# https://github.com/coreos/bootupd/issues/132
+i=1
+while true; do
+    if [ ! -e /dev/disk/by-label/esp-$i ]; then
+        break
+    fi
+    echo "Found ESP (replica $i); updating"
+    mount /dev/disk/by-label/esp-$i /boot/efi
+    cp -rp /usr/lib/bootupd/updates/EFI /boot/efi
+    umount /boot/efi
+    i=$((i+1))
+done
+sync