Added F/W Update Lock File

Added a mutually exclusive, non-blocking FLOCK mechanism in MerlinAU so that whenever AMTM initiates script updates or MerlinAU starts an F/W Update, each one can check the FLOCK mutex to make sure only one of them can perform its intended operation without "stepping on each other's toes" and avoid any possible corruption of a script update.

Author: Martinski4GitHub

MerlinAU.sh

@@ -4,13 +4,13 @@
 #
 # Original Creation Date: 2023-Oct-01 by @ExtremeFiretop.
 # Official Co-Author: @Martinski W. - Date: 2023-Nov-01
-# Last Modified: 2026-Mar-17
+# Last Modified: 2026-Mar-18
 ###################################################################
 set -u
 
 ## Set version for each Production Release ##
 readonly SCRIPT_VERSION=1.6.0
-readonly SCRIPT_VERSTAG="26031700"
+readonly SCRIPT_VERSTAG="26031800"
 readonly SCRIPT_NAME="MerlinAU"
 ## Set to "master" for Production Releases ##
 SCRIPT_BRANCH="dev"
@@ -476,8 +476,7 @@ _AcquireLock_()
    retCode=1
    lockTypeFound=""
    waitTimeoutSecs=0
-   savedVerbose="$isVerbose"
-   isVerbose=true
+   savedVerbose="$isVerbose" ; isVerbose=true
 
    while true
    do
@@ -531,6 +530,66 @@ _AcquireLock_()
    return "$retCode"
 }
 
+##-------------------------------------##
+## Added by Martinski W. [2026-Mar-18] ##
+##-------------------------------------##
+fwupMutexFLock_FD=576
+fwupMutexFLock_FN="/tmp/var/${ScriptFNameTag}_FW_Update.FLock"
+
+_ReleaseMutexFLock_()
+{
+    printf '' > "$fwupMutexFLock_FN"
+    flock -u "$fwupMutexFLock_FD" 2>/dev/null
+}
+
+##-------------------------------------##
+## Added by Martinski W. [2026-Mar-18] ##
+##-------------------------------------##
+#--------------------------------------------------------------#
+# This is a mutually exclusive, non-blocking FLOCK mechanism
+# to be used when MerlinAU is perforning a F/W Update so that
+# AMTM can check and prevent running automatic script updates
+# while the F/W Update is in progress.
+#--------------------------------------------------------------#
+_AcquireMutexFLock_()
+{
+    local retCode  savedVerbose
+    local procInfo  procName=""  procIDno=""  procIDof=""
+
+    savedVerbose="$isVerbose" ; isVerbose=true
+
+    if [ -s "$fwupMutexFLock_FN" ]
+    then
+        procInfo="$(head -n1 "$fwupMutexFLock_FN")"
+        procName="$(echo "$procInfo" | cut -d'|' -f1)"
+        procIDno="$(echo "$procInfo" | cut -d'|' -f2)"
+        if [ -n "$procName" ] && [ -n "$procIDno" ]
+        then procIDof="$(pidof "$procName")"
+        fi
+        if [ -z "$procIDof" ] || ! echo "$procIDof" | grep -qow "$procIDno"
+        then
+            Say "Stale F/W Update Lock Found. Resetting lock file..."
+            _ReleaseMutexFLock_
+        fi
+    fi
+
+    [ ! -s "$fwupMutexFLock_FN" ] && \
+    eval exec "$fwupMutexFLock_FD>$fwupMutexFLock_FN"
+
+    if flock -x -n "$fwupMutexFLock_FD" 2>/dev/null
+    then
+        printf "$(basename "$0")|$$\n" > "$fwupMutexFLock_FN"
+        retCode=0
+    else
+        procInfo="$(head -n1 "$fwupMutexFLock_FN")"
+        Say "${REDct}**ERROR**${NOct}: Another process [$procInfo] has the F/W Update Lock file."
+        retCode=1
+    fi
+
+    isVerbose="$savedVerbose"
+    return "$retCode"
+}
+
 ##-------------------------------------##
 ## Added by Martinski W. [2025-Sep-01] ##
 ##-------------------------------------##
@@ -9126,10 +9185,12 @@ _RunOfflineUpdateNow_()
                 FW_DL_FPATH="${FW_ZIP_DIR}/${FW_FileName}.${extension}"
                 _GnutonBuildSelection_
             fi
-            if _AcquireLock_ cliFileLock
+            if _AcquireLock_ cliFileLock && \
+               _AcquireMutexFLock_
             then
                 _RunFirmwareUpdateNow_
                 _ReleaseLock_ cliFileLock
+                _ReleaseMutexFLock_
             fi
             _ClearOfflineUpdateState_
         else
@@ -9953,10 +10014,12 @@ _PostRebootRunNow_()
 
    Say "END of $logMsg [$curWaitDelaySecs sec.]"
    sleep 30  ## Let's wait a bit & proceed ##
-   if _AcquireLock_ cliFileLock
+   if _AcquireLock_ cliFileLock && \
+      _AcquireMutexFLock_
    then
        _RunFirmwareUpdateNow_
        _ReleaseLock_ cliFileLock
+       _ReleaseMutexFLock_
    fi
 }
 
@@ -11615,10 +11678,12 @@ _MainMenu_()
                  HIDE_ROUTER_SECTION=true
              fi
              ;;
-          1) if _AcquireLock_ cliFileLock
+          1) if _AcquireLock_ cliFileLock && \
+                _AcquireMutexFLock_
              then
                  _RunFirmwareUpdateNow_
                  _ReleaseLock_ cliFileLock
+                 _ReleaseMutexFLock_
                  FlashStarted=false
              fi
              ;;
@@ -11822,10 +11887,12 @@ then
 
    case "$1" in
        run_now)
-           if _AcquireLock_ cliFileLock
+           if _AcquireLock_ cliFileLock && \
+              _AcquireMutexFLock_
            then
                _RunFirmwareUpdateNow_
                _ReleaseLock_ cliFileLock
+               _ReleaseMutexFLock_
            fi
            ;;
        processNodes) _ProcessMeshNodes_ false
@@ -11914,7 +11981,8 @@ then
                        ;;
                    "${SCRIPT_NAME}checkfwupdate" | \
                    "${SCRIPT_NAME}checkfwupdate_bypassDays")
-                       if _AcquireLock_ cliFileLock
+                       if _AcquireLock_ cliFileLock && \
+                          _AcquireMutexFLock_
                        then
                            if [ "$3" = "${SCRIPT_NAME}checkfwupdate_bypassDays" ]
                            then bypassPostponedDays=true
@@ -11923,6 +11991,7 @@ then
                            webguiMode=true
                            _RunFirmwareUpdateNow_
                            _ReleaseLock_ cliFileLock
+                           _ReleaseMutexFLock_
                        fi
                        ;;
                    "${SCRIPT_NAME}scrptupdate" | \

README.md

@@ -1,7 +1,7 @@
 # MerlinAU - AsusWRT-Merlin Firmware Auto Updater
 
 ## v1.6.0
-## 2026-Mar-17
+## 2026-Mar-18
 
 ## WebUI:
 ![image](https://github.com/user-attachments/assets/9c1dff99-9c13-491b-a7fa-aff924d5f02e)