<?php

/**

 * @package binarychoice.system.unix

 * @since 1.0.3

 */



// Log message levels

define('DLOG_TO_CONSOLE', 1);

define('DLOG_NOTICE', 2);

define('DLOG_WARNING', 4);

define('DLOG_ERROR', 8);

define('DLOG_CRITICAL', 16);



/**

 * Daemon base class

 *

 * Requirements:

 * Unix like operating system

 * PHP 4 >= 4.3.0 or PHP 5

 * PHP compiled with:

 * --enable-sigchild

 * --enable-pcntl

 *

 * @package binarychoice.system.unix

 * @author Michal 'Seth' Golebiowski <seth at binarychoice dot pl>

 * @copyright Copyright 2005 Seth

 * @since 1.0.3

 */

class Daemon

{

   /**#@+

    * @access public

    */

   /**

    * User ID

    * 

    * @var int

    * @since 1.0

    */

   var $userID = 99;



   /**

    * Group ID

    * 

    * @var integer

    * @since 1.0

    */

   var $groupID = 99;

   

   /**

    * Terminate daemon when set identity failure ?

    * 

    * @var bool

    * @since 1.0.3

    */

   var $requireSetIdentity = false;



   /**

    * Path to PID file

    * 

    * @var string

    * @since 1.0.1

    */

   var $pidFileLocation = '/tmp/daemon.pid';



   /**

    * Home path

    * 

    * @var string

    * @since 1.0

    */

   var $homePath = '/';

   /**#@-*/





   /**#@+

    * @access protected

    */

   /**

    * Current process ID

    * 

    * @var int

    * @since 1.0

    */

   var $_pid = 0;



   /**

    * Is this process a children

    * 

    * @var boolean

    * @since 1.0

    */

   var $_isChildren = false;



   /**

    * Is daemon running

    * 

    * @var boolean

    * @since 1.0

    */

   var $_isRunning = false;

   /**#@-*/





   /**

    * Constructor

    *

    * @access public

    * @since 1.0

    * @return void

    */

   function __construct()

   {

      error_reporting(0);

      set_time_limit(0);

      ob_implicit_flush();



   }



   /**

    * Starts daemon

    *

    * @access public

    * @since 1.0

    * @return bool

    */

   function start()

   {

      $this->_logMessage('Starting daemon');



      if (!$this->_daemonize())

      {

         $this->_logMessage('Could not start daemon', DLOG_ERROR);



         return false;

      }





      $this->_logMessage('Running...');



      $this->_isRunning = true;





      while ($this->_isRunning)

      {

         $this->_doTask();

      }



      return true;

   }



   /**

    * Stops daemon

    *

    * @access public

    * @since 1.0

    * @return void

    */

   function stop()

   {

      $this->_logMessage('Stoping daemon');



      $this->_isRunning = false;

   }



   /**

    * Do task

    *

    * @access protected

    * @since 1.0

    * @return void

    */

   function _doTask()

   {

          // override this method

   }



   /**

    * Logs message

    *

    * @access protected

    * @since 1.0

    * @return void

    */

   function _logMessage($msg, $level = DLOG_NOTICE)

   {

         // override this method

   }



   /**

    * Daemonize

    *

    * Several rules or characteristics that most daemons possess:

    * 1) Check is daemon already running

    * 2) Fork child process

    * 3) Sets identity

    * 4) Make current process a session laeder

    * 5) Write process ID to file

    * 6) Change home path

    * 7) umask(0)

    * 

    * @access private

    * @since 1.0

    * @return void

    */

   function _daemonize()

   {

      ob_end_flush();



      if ($this->_isDaemonRunning())

      {

         // Deamon is already running. Exiting

         return false;

      }



      if (!$this->_fork())

      {

         // Coudn't fork. Exiting.

         return false;

      }



      if (!$this->_setIdentity() && $this->requireSetIdentity)

      {

         // Required identity set failed. Exiting

         return false;

      }



      if (!posix_setsid())

      {

         $this->_logMessage('Could not make the current process a session leader', DLOG_ERROR);



         return false;

      }



      if (!$fp = @fopen($this->pidFileLocation, 'w'))

      {

         $this->_logMessage('Could not write to PID file', DLOG_ERROR);



         return false;

      }

      else

      {

         fputs($fp, $this->_pid);

         fclose($fp);

      }



      @chdir($this->homePath);

      umask(0);



      declare(ticks = 1);



      pcntl_signal(SIGCHLD, array(&$this, 'sigHandler'));

      pcntl_signal(SIGTERM, array(&$this, 'sigHandler'));



      return true;

   }



   /**

    * Cheks is daemon already running

    *

    * @access private

    * @since 1.0.3

    * @return bool

    */

   function _isDaemonRunning()

   {

      $oldPid = @file_get_contents($this->pidFileLocation);



      if ($oldPid !== false && posix_kill(trim($oldPid),0))

      {

         $this->_logMessage('Daemon already running with PID: '.$oldPid, (DLOG_TO_CONSOLE | DLOG_ERROR));



         return true;

      }

      else

      {

         return false;

      }

   }



   /**

    * Forks process

    *

    * @access private

    * @since 1.0

    * @return bool

    */

   function _fork()

   {

      $this->_logMessage('Forking...');

      

      if (!function_exists('pcntl_fork')) {

      	$this->_logMessage('Forking 2...');

      }

      $pid = pcntl_fork();

      

      if ($pid == -1) // error

      {

         $this->_logMessage('Could not fork', DLOG_ERROR);



         return false;

      }

      else if ($pid) // parent

      {

         $this->_logMessage('Killing parent');



         exit();

      }

      else // children

      {

         $this->_isChildren = true;

         $this->_pid = posix_getpid();



         return true;

      }

   }



   /**

    * Sets identity of a daemon and returns result

    *

    * @access private

    * @since 1.0

    * @return bool

    */

   function _setIdentity()

   {

      if (!posix_setgid($this->groupID) || !posix_setuid($this->userID))

      {

         $this->_logMessage('Could not set identity', DLOG_WARNING);



         return false;

      }

      else

      {

         return true;

      }

   }



   /**

    * Signals handler

    *

    * @access public

    * @since 1.0

    * @return void

    */

   function sigHandler($sigNo)

   {

      switch ($sigNo)

      {

         case SIGTERM:   // Shutdown

            $this->_logMessage('Shutdown signal');

            exit();

            break;



         case SIGCHLD:   // Halt

            $this->_logMessage('Halt signal');

            while (pcntl_waitpid(-1, $status, WNOHANG) > 0);

            break;

      }

   }



   /**

    * Releases daemon pid file

    * This method is called on exit (destructor like)

    *

    * @access public

    * @since 1.0

    * @return void

    */

   function __destruct()

   {

      if ($this->_isChildren && file_exists($this->pidFileLocation))

      {

         $this->_logMessage('Releasing daemon');



         unlink($this->pidFileLocation);

      }

   }

}

?>