gnu-social/lib/daemon.php

<?php
/*
 * Laconica - a distributed open-source microblogging tool
 * Copyright (C) 2008, Controlez-Vous, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

if (!defined('LACONICA')) { exit(1); }

class Daemon {

	function name() {
		return NULL;
	}
	
	function background() {
		$pid = pcntl_fork();
		if ($pid < 0) { # error
			return false;
		} else if ($pid > 0) { # parent
			common_log(LOG_INFO, "Successfully forked.");
			exit(0);
		} else { # child
			return true;
		}
	}

	function alreadyRunning() {

		$pidfilename = $this->pidFilename();

		if (!$pidfilename) {
			return false;
		}
		
		if (!file_exists($pidfilename)) {
			return false;
		}
		$contents = file_get_contents($pidfilename);
		if (posix_kill(trim($contents),0)) {
			return true;
		} else {
			return false;
		}
	}
	
	function writePidFile() {
		$pidfilename = $this->pidFilename();
		
		if (!$pidfilename) {
			return false;
		}
		
		file_put_contents($pidfilename, posix_getpid() . "\n");
	}

	function clearPidFile() {
		$pidfilename = $this->pidFilename();
		unlink($pidfilename);
	}
	
	function pidFilename() {
		$piddir = common_config('daemon', 'piddir');
		if (!$piddir) {
			return NULL;
		}
		$name = $this->name();
		if (!$name) {
			return NULL;
		}
		return $piddir . '/' . $name . '.pid';
	}

	function changeUser() {

		$username = common_config('daemon', 'user');
		
		if ($username) {
			$user_info = posix_getpwnam($username);
			if (!$user_info) {
				common_log(LOG_WARNING, 'Ignoring unknown user for daemon: ' . $username);
			} else {
				common_log(LOG_INFO, "Setting user to " . $username);
				posix_setuid($user_info['uid']);
			}
		}

		$groupname = common_config('daemon', 'group');
		
		if ($groupname) {
			$group_info = posix_getgrnam($groupname);
			if (!$group_info) {
				common_log(LOG_WARNING, 'Ignoring unknown group for daemon: ' . $groupname);
			} else {
				common_log(LOG_INFO, "Setting group to " . $groupname);
				posix_setgid($group_info['gid']);
			}
		}
	}
	
	function runOnce() {
		if ($this->alreadyRunning()) {
			common_log(LOG_INFO, $this->name() . ' already running. Exiting.');
			exit(0);
		}
		if ($this->background()) {
			$this->writePidFile();
			$this->changeUser();
			$this->run();
			$this->clearPidFile();
		}
	}
	
	function run() {
		return true;
	}
}