From 5bfba451f9ea6321de03839b933b4a270cfdaaa3 Mon Sep 17 00:00:00 2001
From: Leonard Kugis <leonard@kug.is>
Date: Tue, 14 Oct 2025 21:19:13 +0200
Subject: service: Added lock to prevent multiple starts of the script on
 startup

---
 service.sh | 49 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 46 insertions(+), 3 deletions(-)

(limited to 'service.sh')

diff --git a/service.sh b/service.sh
index 43f8c75..8cb77c1 100644
--- a/service.sh
+++ b/service.sh
@@ -30,8 +30,50 @@ BOOTWAIT_COUNT_INTERVAL=15
 CONF_MAIN="${MODDIR}/config/main.conf"
 CONF_FSTAB="${MODDIR}/config/fstab.conf"
 
-# Check if configs are readable
+# --- single-run lock (prevents concurrent starts) ---------------------------
+LOCKDIR="${MODDIR}/.runlock"
+PIDFILE="${LOCKDIR}/pid"
+
+acquire_lock() {
+  # Versuche Lock-Verzeichnis atomar anzulegen
+  if mkdir "${LOCKDIR}" 2>/dev/null; then
+    # Lock bekommen
+    echo "$$" > "${PIDFILE}"
+    # Bei Exit Lock säubern
+    trap 'rc=$?; rm -f "${PIDFILE}"; rmdir "${LOCKDIR}" 2>/dev/null; exit $rc' INT TERM EXIT
+    return 0
+  fi
+
+  # Lock existiert -> prüfen, ob stale
+  if [ -f "${PIDFILE}" ]; then
+    oldpid="$(cat "${PIDFILE}" 2>/dev/null)"
+    if [ -n "${oldpid}" ] && [ -d "/proc/${oldpid}" ]; then
+      # Anderer Prozess läuft noch -> sauber beenden
+      echo "Another instance already running (pid ${oldpid}). Exiting." >>"${LOG_FILE}" 2>&1
+      return 1
+    fi
+  fi
+
+  # Stale Lock entfernen und erneut versuchen
+  echo "Stale lock detected, cleaning up..." >>"${LOG_FILE}" 2>&1
+  rm -f "${PIDFILE}" 2>/dev/null
+  rmdir "${LOCKDIR}" 2>/dev/null
 
+  if mkdir "${LOCKDIR}" 2>/dev/null; then
+    echo "$$" > "${PIDFILE}"
+    trap 'rc=$?; rm -f "${PIDFILE}"; rmdir "${LOCKDIR}" 2>/dev/null; exit $rc' INT TERM EXIT
+    return 0
+  else
+    echo "Failed to acquire lock after cleanup. Exiting." >>"${LOG_FILE}" 2>&1
+    return 1
+  fi
+}
+
+# Lock holen; wenn nicht möglich, still beenden
+acquire_lock || exit 0
+# ---------------------------------------------------------------------------
+
+# Check if configs are readable
 if [ ! -r "$CONF_MAIN" ]; then
   echo "File '$CONF_MAIN' not readable." >>"${LOG_FILE}" 2>&1
   exit 2
@@ -57,8 +99,8 @@ if [ ${bootwait_count} -ge ${BOOTWAIT_MAX_COUNT} ]; then
 fi
 
 # prevent log file from growing too large
-tail -n "${LOG_MAX_LINES}" "${LOG_FILE}" >"${LOG_FILE}.tmp"
-mv "${LOG_FILE}.tmp" "${LOG_FILE}"
+tail -n "${LOG_MAX_LINES}" "${LOG_FILE}" >"${LOG_FILE}.tmp" 2>/dev/null
+mv "${LOG_FILE}.tmp" "${LOG_FILE}" 2>/dev/null
 
 echo "=== $(date) ===" >>"${LOG_FILE}" 2>&1
 
@@ -69,3 +111,4 @@ else
 fi
 
 wait
+# Lock wird durch trap am Ende automatisch freigegeben
-- 
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