sanitize locked_at_timestamp to ensure a number

Author: FreekBes

systemd/system/codam-web-greeter-idler.sh

@@ -29,8 +29,14 @@ while IFS= read -r line; do
 	if [ -f "/tmp/codam_web_greeter_lock_timestamp_$USERNAME" ]; then
 		# Get the locked_at_timestamp from the file
 		LOCKED_AT_TIMESTAMP=$(/usr/bin/awk '{print $1}' "/tmp/codam_web_greeter_lock_timestamp_$USERNAME")
-		# Calculate the time since the session was locked
-		TIME_SINCE_LOCK=$((($(date +%s) - LOCKED_AT_TIMESTAMP) * 1000))
+		# Sanitize the timestamp to ensure it's a number
+		if [[ "$LOCKED_AT_TIMESTAMP" =~ ^[0-9]+$ ]]; then
+			# Calculate the time since the session was locked
+			TIME_SINCE_LOCK=$((($(date +%s) - LOCKED_AT_TIMESTAMP) * 1000))
+		else
+			echo "Warning: Invalid timestamp in /tmp/codam_web_greeter_lock_timestamp_$USERNAME: $LOCKED_AT_TIMESTAMP" >&2
+			TIME_SINCE_LOCK=0
+		fi
 	fi
 
 	# Check if session has been idle for long enough