aq_syslog.rb

require 'syslog'

module Aq
  # Clone the ::Syslog module so we can extend it.
  Syslog = ::Syslog.dup

  # Syslog for fields. No need to {::Syslog#open} it, we already did.
  module Syslog
    DEFAULT_OPTIONS = LOG_PID | ($stderr.isatty ? LOG_PERROR : 0)
    DEFAULT_FACILITY = LOG_DAEMON
    FORMAT_SPECIFIERS_MATCH = /[^%](%(?:\d+\$)?[+-]?(?:[ 0]|'.{1})?-?\d*(?:\.\d+)?[a-zA-Z])/

    # Open it with defaults now. Because we can.
    self.open(File.basename($0), DEFAULT_OPTIONS, DEFAULT_FACILITY)

    class << self
      # Alias log so we can override it.
      alias :orig_log :log

      # Override ::Syslog#log to escape format_string when no format_args are
      # passed.
      def log(priority, format_string, *format_args)
        escape_format_string!(format_string) if format_args.empty?
        orig_log(priority, format_string, *format_args)
      end

      # Escape printf style format specifiers. 
      def escape_format_string!(format_string)
        format_string.gsub!(FORMAT_SPECIFIERS_MATCH, '%\1')
      end

      # Override convenience methods here because they ::Syslog versions
      # won't call our #log method.
      def emerg(str, *args); log(::Syslog::LOG_EMERG, str, *args); end
      def alert(str, *args); log(::Syslog::LOG_ALERT, str, *args); end
      def crit(str, *args); log(::Syslog::LOG_CRIT, str, *args); end
      def err(str, *args); log(::Syslog::LOG_ERR, str, *args); end
      def warning(str, *args); log(::Syslog::LOG_WARNING, str, *args); end
      def notice(str, *args); log(::Syslog::LOG_NOTICE, str, *args); end
      def info(str, *args); log(::Syslog::LOG_INFO, str, *args); end
      def debug(str, *args); log(::Syslog::LOG_DEBUG, str, *args); end
    end
  end
end