From 51624008a20340274eb772d28beb390bb51b6417 Mon Sep 17 00:00:00 2001
From: Elias Bakken <elias@iagent.no>
Date: Mon, 10 Aug 2026 21:36:43 +0200
Subject: [PATCH] Always unmount the config partition in
 get-recore-serial-number

set -euo pipefail means a missing serial_number file (a board that
hasn't been provisioned yet - exactly the case this script exists to
detect) makes cat fail and the script exit before reaching
unmount-config, leaving the mount - and its transient systemd unit -
dangling. That stale mount can then make a later mount-config call
fail with "Unit mnt-config.mount was already loaded".

Use a trap so the unmount always runs once the mount has succeeded,
regardless of how the read afterward turns out.

Live-tested on real hardware: deleted serial_number, confirmed the
script now fails cleanly (exit 1, no stale mount) instead of leaving
/mnt/config mounted, then restored the serial number via
create-recore-config and confirmed the whole flow still works.
---
 bin/prod/get-recore-serial-number |  7 ++++++-
 test/bats/getters.bats            | 12 ++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/bin/prod/get-recore-serial-number b/bin/prod/get-recore-serial-number
index 407dc90..be14bc9 100755
--- a/bin/prod/get-recore-serial-number
+++ b/bin/prod/get-recore-serial-number
@@ -5,5 +5,10 @@ set -euo pipefail
 CONFIG_DIR="${REFLASH_CONFIG_DIR:-/mnt/config}"
 
 mount-config
+# A board with no serial number provisioned yet - the exact case this
+# script exists to detect - means serial_number doesn't exist, so cat
+# fails and set -e exits before reaching unmount-config, leaving the
+# mount (and its transient systemd unit) dangling. Make the unmount
+# unconditional instead.
+trap unmount-config EXIT
 cat "$CONFIG_DIR/serial_number"
-unmount-config
diff --git a/test/bats/getters.bats b/test/bats/getters.bats
index 77c3766..ad3766d 100644
--- a/test/bats/getters.bats
+++ b/test/bats/getters.bats
@@ -27,3 +27,15 @@ teardown() { teardown_sandbox; }
   [ "$status" -eq 0 ]
   [ "$output" = "RC-0001-XYZ" ]
 }
+
+@test "get-recore-serial-number: still unmounts when serial_number is missing (#83 fallout)" {
+  export REFLASH_CONFIG_DIR="$SANDBOX/config"
+  mkdir -p "$REFLASH_CONFIG_DIR"
+  # No serial_number file - this is exactly the state a not-yet-provisioned
+  # board is in, i.e. the case this script exists to detect.
+  stub_silent mount-config
+  stub_silent unmount-config
+  run "$PROD_BIN/get-recore-serial-number"
+  [ "$status" -ne 0 ]
+  assert_called_with "unmount-config"
+}