qa-base.php

<?php
/*
	Question2Answer by Gideon Greenspan and contributors
	http://www.question2answer.org/

	File: qa-include/qa-base.php
	Description: Sets up Q2A environment, plus many globally useful functions


	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	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 General Public License for more details.

	More about this license: http://www.question2answer.org/license.php
*/


	define('QA_VERSION', '1.7.3'); // also used as suffix for .js and .css requests
	define('QA_BUILD_DATE', '2016-01-29');


	/**
	 * Autoloads some Q2A classes so it's possible to use them without adding a require_once first. From version 1.7 onwards.
	 * These loosely follow PHP-FIG's PSR-0 standard where faux namespaces are separated by underscores. This is being done
	 * slowly and carefully to maintain backwards compatibility, and does not apply to plugins, themes, nor most of the core
	 * for that matter.
	 *
	 * Classes are stored in the qa-include/Q2A folder, and then in subfolders depending on their categorization.
	 * Class names should be of the form Q2A_<Namespace>_<Class>, e.g. Q2A_Util_Debug. There may be multiple "namespaces".
	 * Classes are mapped to PHP files with the underscores converted to directory separators. The Q2A_Util_Debug class is in
	 * the file qa-include/Q2A/Util/Debug.php. A class named Q2A_Db_User_Messages would be in a file qa-include/Q2A/Db/User/Messages.php.
	 */
	function qa_autoload($class)
	{
		if (strpos($class, 'Q2A_') === 0)
			require QA_INCLUDE_DIR.strtr($class, '_', '/') . '.php';
	}
	spl_autoload_register('qa_autoload');


//	Execution section of this file - remainder contains function definitions

	qa_initialize_php();
	qa_initialize_constants_1();

	if (defined('QA_WORDPRESS_LOAD_FILE')) // if relevant, load WordPress integration in global scope
		require_once QA_WORDPRESS_LOAD_FILE;

	qa_initialize_constants_2();
	qa_initialize_modularity();
	qa_register_core_modules();
	qa_load_plugin_files();
	qa_load_override_files();

	require_once QA_INCLUDE_DIR.'qa-db.php';

	qa_db_allow_connect();


//	Version comparison functions

	function qa_version_to_float($version)
/*
	Converts the $version string (e.g. 1.6.2.2) to a floating point that can be used for greater/lesser comparisons
	(PHP's version_compare() function is not quite suitable for our needs)
*/
	{
		$value=0.0;

		if (preg_match('/[0-9\.]+/', $version, $matches)) {
			$parts=explode('.', $matches[0]);
			$units=1.0;

			foreach ($parts as $part) {
				$value+=min($part, 999)*$units;
				$units/=1000;
			}
		}

		return $value;
	}


	function qa_qa_version_below($version)
/*
	Returns true if the current Q2A version is lower than $version, if both are valid version strings for qa_version_to_float()
*/
	{
		$minqa=qa_version_to_float($version);
		$thisqa=qa_version_to_float(QA_VERSION);

		return $minqa && $thisqa && ($thisqa<$minqa);
	}


	function qa_php_version_below($version)
/*
	Returns true if the current PHP version is lower than $version, if both are valid version strings for qa_version_to_float()
*/
	{
		$minphp=qa_version_to_float($version);
		$thisphp=qa_version_to_float(phpversion());

		return $minphp && $thisphp && ($thisphp<$minphp);
	}


//	Initialization functions called above

	function qa_initialize_php()
/*
	Set up and verify the PHP environment for Q2A, including unregistering globals if necessary
*/
	{
		if (qa_php_version_below('5.1.6'))
			qa_fatal_error('Q2A requires PHP 5.1.6 or later');

		error_reporting(E_ALL); // be ultra-strict about error checking

		@ini_set('magic_quotes_runtime', 0);

		@setlocale(LC_CTYPE, 'C'); // prevent strtolower() et al affecting non-ASCII characters (appears important for IIS)

		if (function_exists('date_default_timezone_set') && function_exists('date_default_timezone_get'))
			@date_default_timezone_set(@date_default_timezone_get()); // prevent PHP notices where default timezone not set

		if (ini_get('register_globals')) {
			$checkarrays=array('_ENV', '_GET', '_POST', '_COOKIE', '_SERVER', '_FILES', '_REQUEST', '_SESSION'); // unregister globals if they're registered
			$keyprotect=array_flip(array_merge($checkarrays, array('GLOBALS')));

			foreach ($checkarrays as $checkarray)
				if ( isset(${$checkarray}) && is_array(${$checkarray}) )
					foreach (${$checkarray} as $checkkey => $checkvalue)
						if (isset($keyprotect[$checkkey]))
							qa_fatal_error('My superglobals are not for overriding');
						else
							unset($GLOBALS[$checkkey]);
		}
	}


	function qa_initialize_constants_1()
/*
	First stage of setting up Q2A constants, before (if necessary) loading WordPress integration
*/
	{
		global $qa_request_map;

		define('QA_CATEGORY_DEPTH', 4); // you can't change this number!

		if (!defined('QA_BASE_DIR'))
			define('QA_BASE_DIR', dirname(dirname(__FILE__)).'/'); // try out best if not set in index.php or qa-index.php - won't work with symbolic links

		define('QA_EXTERNAL_DIR', QA_BASE_DIR.'qa-external/');
		define('QA_INCLUDE_DIR', QA_BASE_DIR.'qa-include/');
		define('QA_LANG_DIR', QA_BASE_DIR.'qa-lang/');
		define('QA_THEME_DIR', QA_BASE_DIR.'qa-theme/');
		define('QA_PLUGIN_DIR', QA_BASE_DIR.'qa-plugin/');

		if (!file_exists(QA_BASE_DIR.'qa-config.php'))
			qa_fatal_error('The config file could not be found. Please read the instructions in qa-config-example.php.');

		require_once QA_BASE_DIR.'qa-config.php';

		$qa_request_map = isset($QA_CONST_PATH_MAP) && is_array($QA_CONST_PATH_MAP) ? $QA_CONST_PATH_MAP : array();

		if (defined('QA_WORDPRESS_INTEGRATE_PATH') && strlen(QA_WORDPRESS_INTEGRATE_PATH)) {
			define('QA_FINAL_WORDPRESS_INTEGRATE_PATH', QA_WORDPRESS_INTEGRATE_PATH.((substr(QA_WORDPRESS_INTEGRATE_PATH, -1)=='/') ? '' : '/'));
			define('QA_WORDPRESS_LOAD_FILE', QA_FINAL_WORDPRESS_INTEGRATE_PATH.'wp-load.php');

			if (!is_readable(QA_WORDPRESS_LOAD_FILE))
				qa_fatal_error('Could not find wp-load.php file for WordPress integration - please check QA_WORDPRESS_INTEGRATE_PATH in qa-config.php');
		}

		// Polyfills

		// JSON compatibility layer for PHP 5.1
		if (!function_exists('json_encode') && !function_exists('json_decode')) {
			require_once QA_INCLUDE_DIR.'vendor/JSON.php';

			function json_encode($json)
			{
				$service = new Services_JSON();
				return $service->encode($json);
			}

			function json_decode($json, $assoc = false)
			{
				$service = new Services_JSON($assoc ? SERVICES_JSON_LOOSE_TYPE : 0);
				return $service->decode($json);
			}
		}

		// password_hash compatibility for 5.3-5.4
		define('QA_PASSWORD_HASH', !qa_php_version_below('5.3.7'));
		if (QA_PASSWORD_HASH) {
			require_once QA_INCLUDE_DIR.'vendor/password_compat.php';
		}
	}


	function qa_initialize_constants_2()
/*
	Second stage of setting up Q2A constants, after (if necessary) loading WordPress integration
*/
	{

	//	Default values if not set in qa-config.php

		@define('QA_COOKIE_DOMAIN', '');
		@define('QA_HTML_COMPRESSION', true);
		@define('QA_MAX_LIMIT_START', 19999);
		@define('QA_IGNORED_WORDS_FREQ', 10000);
		@define('QA_ALLOW_UNINDEXED_QUERIES', false);
		@define('QA_OPTIMIZE_LOCAL_DB', false);
		@define('QA_OPTIMIZE_DISTANT_DB', false);
		@define('QA_PERSISTENT_CONN_DB', false);
		@define('QA_DEBUG_PERFORMANCE', false);

	//	Start performance monitoring

		if (QA_DEBUG_PERFORMANCE) {
			global $qa_usage;
			$qa_usage = new Q2A_Util_Usage;
		}

	//	More for WordPress integration

		if (defined('QA_FINAL_WORDPRESS_INTEGRATE_PATH')) {
			define('QA_FINAL_MYSQL_HOSTNAME', DB_HOST);
			define('QA_FINAL_MYSQL_USERNAME', DB_USER);
			define('QA_FINAL_MYSQL_PASSWORD', DB_PASSWORD);
			define('QA_FINAL_MYSQL_DATABASE', DB_NAME);
			define('QA_FINAL_EXTERNAL_USERS', true);

			// Undo WordPress's addition of magic quotes to various things (leave $_COOKIE as is since WP code might need that)

			function qa_undo_wordpress_quoting($param, $isget)
			{
				if (is_array($param)) { //
					foreach ($param as $key => $value)
						$param[$key]=qa_undo_wordpress_quoting($value, $isget);

				} else {
					$param=stripslashes($param);
					if ($isget)
						$param=strtr($param, array('\\\'' => '\'', '\"' => '"')); // also compensate for WordPress's .htaccess file
				}

				return $param;
			}

			$_GET=qa_undo_wordpress_quoting($_GET, true);
			$_POST=qa_undo_wordpress_quoting($_POST, false);
			$_SERVER['PHP_SELF']=stripslashes($_SERVER['PHP_SELF']);

		} else {
			define('QA_FINAL_MYSQL_HOSTNAME', QA_MYSQL_HOSTNAME);
			define('QA_FINAL_MYSQL_USERNAME', QA_MYSQL_USERNAME);
			define('QA_FINAL_MYSQL_PASSWORD', QA_MYSQL_PASSWORD);
			define('QA_FINAL_MYSQL_DATABASE', QA_MYSQL_DATABASE);
			define('QA_FINAL_EXTERNAL_USERS', QA_EXTERNAL_USERS);
		}

		if (defined('QA_MYSQL_PORT')) {
			define('QA_FINAL_MYSQL_PORT', QA_MYSQL_PORT);
		}

	//	Possible URL schemes for Q2A and the string used for url scheme testing

		define('QA_URL_FORMAT_INDEX', 0);  // http://...../index.php/123/why-is-the-sky-blue
		define('QA_URL_FORMAT_NEAT', 1);   // http://...../123/why-is-the-sky-blue [requires .htaccess]
		define('QA_URL_FORMAT_PARAM', 3);  // http://...../?qa=123/why-is-the-sky-blue
		define('QA_URL_FORMAT_PARAMS', 4); // http://...../?qa=123&qa_1=why-is-the-sky-blue
		define('QA_URL_FORMAT_SAFEST', 5); // http://...../index.php?qa=123&qa_1=why-is-the-sky-blue

		define('QA_URL_TEST_STRING', '$&-_~#%\\@^*()][`\';=:|".{},!<>?# π§½Жש'); // tests escaping, spaces, quote slashing and unicode - but not + and /
	}


	function qa_initialize_modularity()
/*
	Gets everything ready to start using modules, layers and overrides
*/
	{
		global $qa_modules, $qa_layers, $qa_override_files, $qa_overrides, $qa_direct;

		$qa_modules=array();
		$qa_layers=array();
		$qa_override_files=array();
		$qa_overrides=array();
		$qa_direct=array();
	}


	function qa_register_core_modules()
/*
	Register all modules that come as part of the Q2A core (as opposed to plugins)
*/
	{
		qa_register_module('filter', 'plugins/qa-filter-basic.php', 'qa_filter_basic', '');
		qa_register_module('editor', 'plugins/qa-editor-basic.php', 'qa_editor_basic', '');
		qa_register_module('viewer', 'plugins/qa-viewer-basic.php', 'qa_viewer_basic', '');
		qa_register_module('event', 'plugins/qa-event-limits.php', 'qa_event_limits', 'Q2A Event Limits');
		qa_register_module('event', 'plugins/qa-event-notify.php', 'qa_event_notify', 'Q2A Event Notify');
		qa_register_module('event', 'plugins/qa-event-updates.php', 'qa_event_updates', 'Q2A Event Updates');
		qa_register_module('search', 'plugins/qa-search-basic.php', 'qa_search_basic', '');
		qa_register_module('widget', 'plugins/qa-widget-activity-count.php', 'qa_activity_count', 'Activity Count');
		qa_register_module('widget', 'plugins/qa-widget-ask-box.php', 'qa_ask_box', 'Ask Box');
		qa_register_module('widget', 'plugins/qa-widget-related-qs.php', 'qa_related_qs', 'Related Questions');
		qa_register_module('widget', 'plugins/qa-widget-category-list.php', 'qa_category_list', 'Categories');
	}


	/**
	 * Retrieve metadata information from the $contents of a qa-theme.php or qa-plugin.php file, specified by $type ('Plugin' or 'Theme').
	 * If $versiononly is true, only min version metadata is parsed.
	 * Name, Description, Min Q2A & Min PHP are not currently used by themes.
	 *
	 * @deprecated Deprecated from 1.7; Q2A_Util_Metadata class and metadata.json files should be used instead
	 */
	function qa_addon_metadata($contents, $type, $versiononly=false)
	{
		$fields = array(
			'min_q2a' => 'Minimum Question2Answer Version',
			'min_php' => 'Minimum PHP Version',
		);
		if (!$versiononly) {
			$fields = array_merge($fields, $fields = array(
				'name' => 'Name',
				'uri' => 'URI',
				'description' => 'Description',
				'version' => 'Version',
				'date' => 'Date',
				'author' => 'Author',
				'author_uri' => 'Author URI',
				'license' => 'License',
				'update_uri' => 'Update Check URI',
			));
		}

		$metadata = array();
		foreach ($fields as $key => $field) {
			// prepend 'Theme'/'Plugin' and search for key data
			$fieldregex = str_replace(' ', '[ \t]*', preg_quote("$type $field", '/'));
			if (preg_match('/'.$fieldregex.':[ \t]*([^\n\f]*)[\n\f]/i', $contents, $matches))
				$metadata[$key] = trim($matches[1]);
		}

		return $metadata;
	}


	function qa_load_plugin_files()
/*
	Load all the qa-plugin.php files from plugins that are compatible with this version of Q2A
*/
	{
		global $qa_plugin_directory, $qa_plugin_urltoroot;

		$pluginfiles = glob(QA_PLUGIN_DIR.'*/qa-plugin.php');

		$metadataUtil = new Q2A_Util_Metadata();
		foreach ($pluginfiles as $pluginfile) {
			$pluginDirectory = dirname($pluginfile);

			$metadata = $metadataUtil->fetchFromAddonPath($pluginDirectory);
			if (empty($metadata)) {
				// limit plugin parsing to first 8kB
				$contents = file_get_contents($pluginfile, false, null, -1, 8192);
				$metadata = qa_addon_metadata($contents, 'Plugin', true);
			}

			// skip plugin which requires a later version of Q2A
			if (isset($metadata['min_q2a']) && qa_qa_version_below($metadata['min_q2a']))
				continue;
			// skip plugin which requires a later version of PHP
			if (isset($metadata['min_php']) && qa_php_version_below($metadata['min_php']))
				continue;

			// these variables are utilized in the qa_register_plugin_* functions
			$qa_plugin_directory = $pluginDirectory . '/';
			$qa_plugin_urltoroot = substr($qa_plugin_directory, strlen(QA_BASE_DIR));

			require_once $pluginfile;
		}

		$qa_plugin_directory = null;
		$qa_plugin_urltoroot = null;
	}


	function qa_load_override_files()
/*
	Apply all the function overrides in override files that have been registered by plugins
*/
	{
		global $qa_override_files, $qa_overrides;

		$functionindex=array();

		foreach ($qa_override_files as $index => $override) {
			$filename=$override['directory'].$override['include'];
			$functionsphp=file_get_contents($filename);

			preg_match_all('/\Wfunction\s+(qa_[a-z_]+)\s*\(/im', $functionsphp, $rawmatches, PREG_PATTERN_ORDER|PREG_OFFSET_CAPTURE);

			$reversematches=array_reverse($rawmatches[1], true); // reverse so offsets remain correct as we step through
			$postreplace=array();
			$suffix='_in_'.preg_replace('/[^A-Za-z0-9_]+/', '_', basename($override['include']));
				// include file name in defined function names to make debugging easier if there is an error

			foreach ($reversematches as $rawmatch) {
				$function=strtolower($rawmatch[0]);
				$position=$rawmatch[1];

				if (isset($qa_overrides[$function]))
					$postreplace[$function.'_base']=$qa_overrides[$function];

				$newname=$function.'_override_'.(@++$functionindex[$function]).$suffix;
				$functionsphp=substr_replace($functionsphp, $newname, $position, strlen($function));
				$qa_overrides[$function]=$newname;
			}

			foreach ($postreplace as $oldname => $newname)
				if (preg_match_all('/\W('.preg_quote($oldname).')\s*\(/im', $functionsphp, $matches, PREG_PATTERN_ORDER|PREG_OFFSET_CAPTURE)) {
					$searchmatches=array_reverse($matches[1]);
					foreach ($searchmatches as $searchmatch)
						$functionsphp=substr_replace($functionsphp, $newname, $searchmatch[1], strlen($searchmatch[0]));
				}

		//	echo '<pre style="text-align:left;">'.htmlspecialchars($functionsphp).'</pre>'; // to debug munged code

			qa_eval_from_file($functionsphp, $filename);
		}
	}


//	Functions for registering different varieties of Q2A modularity

	function qa_register_module($type, $include, $class, $name, $directory=QA_INCLUDE_DIR, $urltoroot=null)
/*
	Register a module of $type named $name, whose class named $class is defined in file $include (or null if no include necessary)
	If this module comes from a plugin, pass in the local plugin $directory and the $urltoroot relative url for that directory
*/
	{
		global $qa_modules;

		$previous=@$qa_modules[$type][$name];

		if (isset($previous))
			qa_fatal_error('A '.$type.' module named '.$name.' already exists. Please check there are no duplicate plugins. '.
				"\n\nModule 1: ".$previous['directory'].$previous['include']."\nModule 2: ".$directory.$include);

		$qa_modules[$type][$name]=array(
			'directory' => $directory,
			'urltoroot' => $urltoroot,
			'include' => $include,
			'class' => $class,
		);
	}


	function qa_register_layer($include, $name, $directory=QA_INCLUDE_DIR, $urltoroot=null)
/*
	Register a layer named $name, defined in file $include. If this layer comes from a plugin (as all currently do),
	pass in the local plugin $directory and the $urltoroot relative url for that directory
*/
	{
		global $qa_layers;

		$previous=@$qa_layers[$name];

		if (isset($previous))
			qa_fatal_error('A layer named '.$name.' already exists. Please check there are no duplicate plugins. '.
				"\n\nLayer 1: ".$previous['directory'].$previous['include']."\nLayer 2: ".$directory.$include);

		$qa_layers[$name]=array(
			'directory' => $directory,
			'urltoroot' => $urltoroot,
			'include' => $include,
		);
	}


	function qa_register_overrides($include, $directory=QA_INCLUDE_DIR, $urltoroot=null)
/*
	Register a file $include containing override functions. If this file comes from a plugin (as all currently do),
	pass in the local plugin $directory and the $urltoroot relative url for that directory
*/
	{
		global $qa_override_files;

		$qa_override_files[]=array(
			'directory' => $directory,
			'urltoroot' => $urltoroot,
			'include' => $include
		);
	}


	function qa_register_phrases($pattern, $name)
/*
	Register a set of language phrases, which should be accessed by the prefix $name/ in the qa_lang_*() functions.
	Pass in the $pattern representing the PHP files that define these phrases, where * in the pattern is replaced with
	the language code (e.g. 'fr') and/or 'default'. These files should be formatted like Q2A's qa-lang-*.php files.
*/
	{
		global $qa_lang_file_pattern;

		if (file_exists(QA_INCLUDE_DIR.'lang/qa-lang-'.$name.'.php'))
			qa_fatal_error('The name "'.$name.'" for phrases is reserved and cannot be used by plugins.'."\n\nPhrases: ".$pattern);

		if (isset($qa_lang_file_pattern[$name]))
			qa_fatal_error('A set of phrases named '.$name.' already exists. Please check there are no duplicate plugins. '.
				"\n\nPhrases 1: ".$qa_lang_file_pattern[$name]."\nPhrases 2: ".$pattern);

		$qa_lang_file_pattern[$name]=$pattern;
	}


//	Function for registering varieties of Q2A modularity, which are (only) called from qa-plugin.php files

	function qa_register_plugin_module($type, $include, $class, $name)
/*
	Register a plugin module of $type named $name, whose class named $class is defined in file $include (or null if no include necessary)
	This function relies on some global variable values and can only be called from a plugin's qa-plugin.php file
*/
	{
		global $qa_plugin_directory, $qa_plugin_urltoroot;

		if (empty($qa_plugin_directory) || empty($qa_plugin_urltoroot))
			qa_fatal_error('qa_register_plugin_module() can only be called from a plugin qa-plugin.php file');

		qa_register_module($type, $include, $class, $name, $qa_plugin_directory, $qa_plugin_urltoroot);
	}


	function qa_register_plugin_layer($include, $name)
/*
	Register a plugin layer named $name, defined in file $include. Can only be called from a plugin's qa-plugin.php file
*/
	{
		global $qa_plugin_directory, $qa_plugin_urltoroot;

		if (empty($qa_plugin_directory) || empty($qa_plugin_urltoroot))
			qa_fatal_error('qa_register_plugin_layer() can only be called from a plugin qa-plugin.php file');

		qa_register_layer($include, $name, $qa_plugin_directory, $qa_plugin_urltoroot);
	}


	function qa_register_plugin_overrides($include)
/*
	Register a plugin file $include containing override functions. Can only be called from a plugin's qa-plugin.php file
*/
	{
		global $qa_plugin_directory, $qa_plugin_urltoroot;

		if (empty($qa_plugin_directory) || empty($qa_plugin_urltoroot))
			qa_fatal_error('qa_register_plugin_overrides() can only be called from a plugin qa-plugin.php file');

		qa_register_overrides($include, $qa_plugin_directory, $qa_plugin_urltoroot);
	}


	function qa_register_plugin_phrases($pattern, $name)
/*
	Register a file name $pattern within a plugin directory containing language phrases accessed by the prefix $name
*/
	{
		global $qa_plugin_directory, $qa_plugin_urltoroot;

		if (empty($qa_plugin_directory) || empty($qa_plugin_urltoroot))
			qa_fatal_error('qa_register_plugin_phrases() can only be called from a plugin qa-plugin.php file');

		qa_register_phrases($qa_plugin_directory.$pattern, $name);
	}


//	Low-level functions used throughout Q2A

	/**
	 * Calls eval() on the PHP code in $eval which came from the file $filename. It supplements PHP's regular error reporting by
	 * displaying/logging (as appropriate) the original source filename, if an error occurred when evaluating the code.
	 */
	function qa_eval_from_file($eval, $filename)
	{
		// could also use ini_set('error_append_string') but apparently it doesn't work for errors logged on disk

		global $php_errormsg;

		$oldtrackerrors=@ini_set('track_errors', 1);
		$php_errormsg=null;

		eval('?'.'>'.$eval);

		if (strlen($php_errormsg)) {
			switch (strtolower(@ini_get('display_errors'))) {
				case 'on': case '1': case 'yes': case 'true': case 'stdout': case 'stderr':
					echo ' of '.qa_html($filename)."\n";
					break;
			}

			@error_log('PHP Question2Answer more info: '.$php_errormsg." in eval()'d code from ".qa_html($filename));
		}

		@ini_set('track_errors', $oldtrackerrors);
	}


	/**
	 * Call $function with the arguments in the $args array (doesn't work with call-by-reference functions)
	 */
	function qa_call($function, $args)
	{
		// call_user_func_array(...) is very slow, so we break out most common cases first
		switch (count($args)) {
			case 0:
				return $function();
			case 1:
				return $function($args[0]);
			case 2:
				return $function($args[0], $args[1]);
			case 3:
				return $function($args[0], $args[1], $args[2]);
			case 4:
				return $function($args[0], $args[1], $args[2], $args[3]);
			case 5:
				return $function($args[0], $args[1], $args[2], $args[3], $args[4]);
		}

		return call_user_func_array($function, $args);
	}


	/**
	 * Determines whether a function is to be overridden by a plugin. But if the function is being called with
	 * the _base suffix, any override will be bypassed due to $qa_direct.
	 *
	 * @param string $function The function to override
	 * @return string|null The name of the overriding function (of the form `qa_functionname_override_1_in_filename`)
	 */
	function qa_to_override($function)
	{
		global $qa_overrides, $qa_direct;

		// handle most common case first
		if (!isset($qa_overrides[$function])) {
			return null;
		}

		if (strpos($function, '_override_')!==false) {
			qa_fatal_error('Override functions should not be calling qa_to_override()!');
		}

		if (@$qa_direct[$function]) {
			unset($qa_direct[$function]); // bypass the override just this once
			return null;
		}

		return $qa_overrides[$function];
	}


	function qa_call_override($function, $args)
/*
	Call the function which immediately overrides $function with the arguments in the $args array
*/
	{
		global $qa_overrides;

		if (strpos($function, '_override_')!==false)
			qa_fatal_error('Override functions should not be calling qa_call_override()!');

		if (!function_exists($function.'_base')) // define the base function the first time that it's needed
			eval('function '.$function.'_base() { global $qa_direct; $qa_direct[\''.$function.'\']=true; $args=func_get_args(); return qa_call(\''.$function.'\', $args); }');

		return qa_call($qa_overrides[$function], $args);
	}


	function qa_exit($reason=null)
/*
	Exit PHP immediately after reporting a shutdown with $reason to any installed process modules
*/
	{
		qa_report_process_stage('shutdown', $reason);
		exit;
	}


	function qa_fatal_error($message)
/*
	Display $message in the browser, write it to server error log, and then stop abruptly
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		echo 'Question2Answer fatal error:<p><font color="red">'.qa_html($message, true).'</font></p>';
		@error_log('PHP Question2Answer fatal error: '.$message);
		echo '<p>Stack trace:<p>';

		$backtrace=array_reverse(array_slice(debug_backtrace(), 1));
		foreach ($backtrace as $trace)
			echo '<font color="#'.((strpos(@$trace['file'], '/qa-plugin/')!==false) ? 'f00' : '999').'">'.
				qa_html(@$trace['function'].'() in '.basename(@$trace['file']).':'.@$trace['line']).'</font><br>';

		qa_exit('error');
	}


//	Functions for listing, loading and getting info on modules

	function qa_list_modules_info()
/*
	Return an array with all registered modules' information
*/
	{
		global $qa_modules;
		return $qa_modules;
	}

	function qa_list_module_types()
/*
	Return an array of all the module types for which at least one module has been registered
*/
	{
		return array_keys(qa_list_modules_info());
	}

	function qa_list_modules($type)
/*
	Return a list of names of registered modules of $type
*/
	{
		$modules = qa_list_modules_info();
		return is_array(@$modules[$type]) ? array_keys($modules[$type]) : array();
	}

	function qa_get_module_info($type, $name)
/*
	Return an array containing information about the module of $type named $name
*/
	{
		$modules = qa_list_modules_info();
		return @$modules[$type][$name];
	}

	function qa_load_module($type, $name)
/*
	Return an instantiated class for module of $type named $name, whose functions can be called, or null if it doesn't exist
*/
	{
		global $qa_modules;

		$module = @$qa_modules[$type][$name];

		if (is_array($module)) {
			if (isset($module['object']))
				return $module['object'];

			if (strlen(@$module['include']))
				require_once $module['directory'].$module['include'];

			if (strlen(@$module['class'])) {
				$object = new $module['class'];

				if (method_exists($object, 'load_module'))
					$object->load_module($module['directory'], qa_path_to_root().$module['urltoroot'], $type, $name);

				$qa_modules[$type][$name]['object'] = $object;
				return $object;
			}
		}

		return null;
	}

	function qa_load_all_modules_with($method)
/*
	Return an array of instantiated clases for modules which have defined $method
	(all modules are loaded but not included in the returned array)
*/
	{
		$modules = array();

		$regmodules = qa_list_modules_info();

		foreach ($regmodules as $moduletype => $modulesinfo) {
			foreach ($modulesinfo as $modulename => $moduleinfo) {
				$module = qa_load_module($moduletype, $modulename);

				if (method_exists($module, $method))
					$modules[$modulename] = $module;
			}
		}

		return $modules;
	}

	function qa_load_modules_with($type, $method)
/*
	Return an array of instantiated clases for modules of $type which have defined $method
	(other modules of that type are also loaded but not included in the returned array)
*/
	{
		$modules = array();

		$trynames = qa_list_modules($type);

		foreach ($trynames as $tryname) {
			$module = qa_load_module($type, $tryname);

			if (method_exists($module, $method))
				$modules[$tryname] = $module;
		}

		return $modules;
	}


//	HTML and Javascript escaping and sanitization

	function qa_html($string, $multiline=false)
/*
	Return HTML representation of $string, work well with blocks of text if $multiline is true
*/
	{
		$html=htmlspecialchars((string)$string);

		if ($multiline) {
			$html=preg_replace('/\r\n?/', "\n", $html);
			$html=preg_replace('/(?<=\s) /', '&nbsp;', $html);
			$html=str_replace("\t", '&nbsp; &nbsp; ', $html);
			$html=nl2br($html);
		}

		return $html;
	}


	function qa_sanitize_html($html, $linksnewwindow=false, $storage=false)
/*
	Return $html after ensuring it is safe, i.e. removing Javascripts and the like - uses htmLawed library
	Links open in a new window if $linksnewwindow is true. Set $storage to true if sanitization is for
	storing in the database, rather than immediate display to user - some think this should be less strict.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		require_once 'vendor/htmLawed.php';

		global $qa_sanitize_html_newwindow;

		$qa_sanitize_html_newwindow=$linksnewwindow;

		$safe=htmLawed($html, array(
			'safe' => 1,
			'elements' => '*+embed+object-form',
			'schemes' => 'href: aim, feed, file, ftp, gopher, http, https, irc, mailto, news, nntp, sftp, ssh, telnet; *:file, http, https; style: !; classid:clsid',
			'keep_bad' => 0,
			'anti_link_spam' => array('/.*/', ''),
			'hook_tag' => 'qa_sanitize_html_hook_tag',
		));

		return $safe;
	}


	function qa_sanitize_html_hook_tag($element, $attributes=null)
/*
	htmLawed hook function used to process tags in qa_sanitize_html(...)
*/
	{
		global $qa_sanitize_html_newwindow;

		if (!isset($attributes)) // it's a closing tag
			return '</'.$element.'>';

		if ( ($element=='param') && (trim(strtolower(@$attributes['name']))=='allowscriptaccess') )
			$attributes['name']='allowscriptaccess_denied';

		if ($element=='embed')
			unset($attributes['allowscriptaccess']);

		if (($element=='a') && isset($attributes['href']) && $qa_sanitize_html_newwindow)
			$attributes['target']='_blank';

		$html='<'.$element;
		foreach ($attributes as $key => $value)
			$html.=' '.$key.'="'.$value.'"';

		return $html.'>';
	}


	function qa_xml($string)
/*
	Return XML representation of $string, which is similar to HTML but ASCII control characters are also disallowed
*/
	{
		return htmlspecialchars(preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F]/', '', (string)$string));
	}


	function qa_js($value, $forcequotes=false)
/*
	Return JavaScript representation of $value, putting in quotes if non-numeric or if $forcequotes is true. In the
	case of boolean values they are returned as the appropriate true or false string
*/
	{
		$boolean = is_bool($value);
		if ($boolean)
			$value = $value ? 'true' : 'false';
		if ((is_numeric($value) || $boolean) && !$forcequotes)
			return $value;
		else
			return "'".strtr($value, array(
				"'" => "\\'",
				'/' => '\\/',
				'\\' => '\\\\',
				"\n" => "\\n",
				"\r" => "\\n",
			))."'";
	}


//	Finding out more about the current request

	function qa_set_request($request, $relativeroot, $usedformat=null)
/*
	Inform Q2A that the current request is $request (slash-separated, independent of the url scheme chosen),
	that the relative path to the Q2A root apperas to be $relativeroot, and the url scheme appears to be $usedformat
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_request, $qa_root_url_relative, $qa_used_url_format;

		$qa_request=$request;
		$qa_root_url_relative=$relativeroot;
		$qa_used_url_format=$usedformat;
	}


	function qa_request()
/*
	Returns the current Q2A request (slash-separated, independent of the url scheme chosen)
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_request;
		return $qa_request;
	}


	function qa_request_part($part)
/*
	Returns the indexed $part (as separated by slashes) of the current Q2A request, or null if it doesn't exist
*/
	{
		$parts=explode('/', qa_request());
		return @$parts[$part];
	}


	function qa_request_parts($start=0)
/*
	Returns an array of parts (as separated by slashes) of the current Q2A request, starting at part $start
*/
	{
		return array_slice(explode('/', qa_request()), $start);
	}


	function qa_gpc_to_string($string)
/*
	Return string for incoming GET/POST/COOKIE value, stripping slashes if appropriate
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return get_magic_quotes_gpc() ? stripslashes($string) : $string;
	}


	function qa_string_to_gpc($string)
/*
	Return string with slashes added, if appropriate for later removal by qa_gpc_to_string()
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return get_magic_quotes_gpc() ? addslashes($string) : $string;
	}


	function qa_get($field)
/*
	Return string for incoming GET field, or null if it's not defined
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return isset($_GET[$field]) ? qa_gpc_to_string($_GET[$field]) : null;
	}


	function qa_post_text($field)
/*
	Return string for incoming POST field, or null if it's not defined.
	While we're at it, trim() surrounding white space and converted to Unix line endings.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return isset($_POST[$field]) ? preg_replace('/\r\n?/', "\n", trim(qa_gpc_to_string($_POST[$field]))) : null;
	}

	function qa_post_array($field)
/*
	Return an array for incoming POST field, or null if it's not an array or not defined.
	While we're at it, trim() surrounding white space for each value and convert them to Unix line endings.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		if (!isset($_POST[$field]) || !is_array($_POST[$field])) {
			return null;
		}

		$result = array();
		foreach ($_POST[$field] as $key => $value)
			$result[$key] = preg_replace('/\r\n?/', "\n", trim(qa_gpc_to_string($value)));

		return $result;
	}


	function qa_clicked($name)
/*
	Return true if form button $name was clicked (as type=submit/image) to create this page request, or if a
	simulated click was sent for the button (via 'qa_click' POST field)
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return isset($_POST[$name]) || isset($_POST[$name.'_x']) || (qa_post_text('qa_click')==$name);
	}


	/**
	 * Determine the remote IP address of the user accessing the site.
	 * @return mixed  String representing IP if it's available, or null otherwise.
	 */
	function qa_remote_ip_address()
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return isset($_SERVER['REMOTE_ADDR']) ? $_SERVER['REMOTE_ADDR'] : null;
	}


	function qa_post_limit_exceeded()
/*
	Checks whether an HTTP request has exceeded the post_max_size PHP variable. This happens whenever an HTTP request
	is too big to be properly processed by PHP, usually because there is an attachment in the HTTP request. A warning
	is added to the server's log displaying the size of the file that triggered this situation. It is important to note
	that whenever this happens the $_POST and $_FILES superglobals are empty.
*/
	{
		if (in_array($_SERVER['REQUEST_METHOD'], array('POST', 'PUT')) && empty($_POST) && empty($_FILES)) {
			$postmaxsize = ini_get('post_max_size');  // Gets the current post_max_size configuration
			$unit = substr($postmaxsize, -1);
			if (!is_numeric($unit)) {
				$postmaxsize = substr($postmaxsize, 0, -1);
			}
			// Gets an integer value that can be compared against the size of the HTTP request
			$postmaxsize = convert_to_bytes($unit, $postmaxsize);
			return $_SERVER['CONTENT_LENGTH'] > $postmaxsize;
		}
	}


	/**
	* Turns a numeric value and a unit (g/m/k) into bytes
	* @param string $unit One of 'g', 'm', 'k'. It is case insensitive
	* @param int $value The value to turn into bytes
	* @return int The amount of bytes the unit and the value represent. If the unit is not one of 'g', 'm' or 'k' then
	* the original value is returned
	*/
	function convert_to_bytes($unit, $value)
	{
		switch (strtolower($unit)) {
			case 'g':
				return $value * 1073741824;
			case 'm':
				return $value * 1048576;
			case 'k':
				return $value * 1024;
			default:
				return $value;
		}
	}


	/**
	 * Whether we are responding to an HTTP GET request
	 * @return bool True if the request is GET
	 */
	function qa_is_http_get()
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return $_SERVER['REQUEST_METHOD'] === 'GET';
	}

	/**
	 * Return true if we are responding to an HTTP POST request
	 */
	function qa_is_http_post()
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return $_SERVER['REQUEST_METHOD'] === 'POST' || !empty($_POST);
	}


	function qa_is_https_probably()
/*
	Return true if we appear to be responding to a secure HTTP request (but hard to be sure)
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return (@$_SERVER['HTTPS'] && ($_SERVER['HTTPS']!='off')) || (@$_SERVER['SERVER_PORT']==443);
	}


	function qa_is_human_probably()
/*
	Return true if it appears the page request is coming from a human using a web browser, rather than a search engine
	or other bot. Based on a whitelist of terms in user agents, this can easily be tricked by a scraper or bad bot.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		require_once QA_INCLUDE_DIR.'util/string.php';

		$useragent=@$_SERVER['HTTP_USER_AGENT'];

		return (strlen($useragent)==0) || qa_string_matches_one($useragent, array(
			'MSIE', 'Firefox', 'Chrome', 'Safari', 'Opera', 'Gecko', 'MIDP', 'PLAYSTATION', 'Teleca',
			'BlackBerry', 'UP.Browser', 'Polaris', 'MAUI_WAP_Browser', 'iPad', 'iPhone', 'iPod'
		));
	}


	function qa_is_mobile_probably()
/*
	Return true if it appears that the page request is coming from a mobile client rather than a desktop/laptop web browser
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		require_once QA_INCLUDE_DIR.'util/string.php';

		// inspired by: http://dangerousprototypes.com/docs/PhpBB3_MOD:_Replacement_mobile_browser_detection_for_mobile_themes

		$loweragent=strtolower(@$_SERVER['HTTP_USER_AGENT']);

		if (strpos($loweragent, 'ipad')!==false) // consider iPad as desktop
			return false;

		$mobileheaders=array('HTTP_X_OPERAMINI_PHONE', 'HTTP_X_WAP_PROFILE', 'HTTP_PROFILE');

		foreach ($mobileheaders as $header)
			if (isset($_SERVER[$header]))
				return true;

		if (qa_string_matches_one($loweragent, array(
			'android', 'phone', 'mobile', 'windows ce', 'palm', ' mobi', 'wireless', 'blackberry', 'opera mini', 'symbian',
			'nokia', 'samsung', 'ericsson,', 'vodafone/', 'kindle', 'ipod', 'wap1.', 'wap2.', 'sony', 'sanyo', 'sharp',
			'panasonic', 'philips', 'pocketpc', 'avantgo', 'blazer', 'ipaq', 'up.browser', 'up.link', 'mmp', 'smartphone', 'midp'
		)))
			return true;

		return qa_string_matches_one(strtolower(@$_SERVER['HTTP_ACCEPT']), array(
			'application/vnd.wap.xhtml+xml', 'text/vnd.wap.wml'
		));
	}


//	Language phrase support

	/**
	 * Return the translated string for $identifier, unless we're using external translation logic.
	 * This will retrieve the 'site_language' option so make sure you've already loaded/set that if
	 * loading an option now will cause a problem (see issue in qa_default_option()). The part of
	 * $identifier before the slash (/) replaces the * in the qa-lang-*.php file references, and the
	 * part after the / is the key of the array element to be taken from that file's returned result.
	 */
	function qa_lang($identifier)
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_lang_file_pattern, $qa_phrases_full;

		list($group, $label) = explode('/', $identifier, 2);

		if (isset($qa_phrases_full[$group][$label]))
			return $qa_phrases_full[$group][$label];

		if (!isset($qa_phrases_full[$group])) {
			// load the default language files
			if (isset($qa_lang_file_pattern[$group]))
				$include = str_replace('*', 'default', $qa_lang_file_pattern[$group]);
			else
				$include = QA_INCLUDE_DIR.'lang/qa-lang-'.$group.'.php';

			$qa_phrases_full[$group] = is_file($include) ? (array)(include_once $include) : array();

			// look for a localized file in qa-lang/<lang>/
			$languagecode = qa_opt('site_language');
			if (strlen($languagecode)) {
				if (isset($qa_lang_file_pattern[$group]))
					$include = str_replace('*', $languagecode, $qa_lang_file_pattern[$group]);
				else
					$include = QA_LANG_DIR.$languagecode.'/qa-lang-'.$group.'.php';

				$phrases = is_file($include) ? (array)(include $include) : array();
				$qa_phrases_full[$group] = array_merge($qa_phrases_full[$group], $phrases);
			}

			// add any custom phrases from qa-lang/custom/
			$include = QA_LANG_DIR.'custom/qa-lang-'.$group.'.php';
			$phrases = is_file($include) ? (array)(include $include) : array();
			$qa_phrases_full[$group] = array_merge($qa_phrases_full[$group], $phrases);

			if (isset($qa_phrases_full[$group][$label]))
				return $qa_phrases_full[$group][$label];
		}

		return '['.$identifier.']'; // as a last resort, return the identifier to help in development
	}


	function qa_lang_sub($identifier, $textparam, $symbol='^')
/*
	Return the translated string for $identifier, with $symbol substituted for $textparam
*/
	{
		return str_replace($symbol, $textparam, qa_lang($identifier));
	}


	function qa_lang_html($identifier)
/*
	Return the translated string for $identifier, converted to HTML
*/
	{
		return qa_html(qa_lang($identifier));
	}


	function qa_lang_html_sub($identifier, $htmlparam, $symbol='^')
/*
	Return the translated string for $identifier converted to HTML, with $symbol *then* substituted for $htmlparam
*/
	{
		return str_replace($symbol, $htmlparam, qa_lang_html($identifier));
	}


	function qa_lang_html_sub_split($identifier, $htmlparam, $symbol='^')
/*
	Return an array containing the translated string for $identifier converted to HTML, then split into three,
	with $symbol substituted for $htmlparam in the 'data' element, and obvious 'prefix' and 'suffix' elements
*/
	{
		$html=qa_lang_html($identifier);

		$symbolpos=strpos($html, $symbol);
		if (!is_numeric($symbolpos))
			qa_fatal_error('Missing '.$symbol.' in language string '.$identifier);

		return array(
			'prefix' => substr($html, 0, $symbolpos),
			'data' => $htmlparam,
			'suffix' => substr($html, $symbolpos+1),
		);
	}


//	Request and path generation

	function qa_path_to_root()
/*
	Return the relative path to the Q2A root (if it was previously set by qa_set_request())
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_root_url_relative;
		return $qa_root_url_relative;
	}


	function qa_get_request_map()
/*
	Return an array of mappings of Q2A requests, as defined in the qa-config.php file
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_request_map;
		return $qa_request_map;
	}


	function qa_path($request, $params=null, $rooturl=null, $neaturls=null, $anchor=null)
/*
	Return the relative URI path for $request, with optional parameters $params and $anchor.
	Slashes in $request will not be urlencoded, but any other characters will.
	If $neaturls is set, use that, otherwise retrieve the option. If $rooturl is set, take
	that as the root of the Q2A site, otherwise use path to root which was set elsewhere.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		if (!isset($neaturls)) {
			require_once QA_INCLUDE_DIR.'app/options.php';
			$neaturls=qa_opt('neat_urls');
		}

		if (!isset($rooturl))
			$rooturl=qa_path_to_root();

		$url=$rooturl.( (empty($rooturl) || (substr($rooturl, -1)=='/') ) ? '' : '/');
		$paramsextra='';

		$requestparts=explode('/', $request);
		$pathmap=qa_get_request_map();

		if (isset($pathmap[$requestparts[0]])) {
			$newpart=$pathmap[$requestparts[0]];

			if (strlen($newpart))
				$requestparts[0]=$newpart;
			elseif (count($requestparts)==1)
				array_shift($requestparts);
		}

		foreach ($requestparts as $index => $requestpart)
			$requestparts[$index]=urlencode($requestpart);
		$requestpath=implode('/', $requestparts);

		switch ($neaturls) {
			case QA_URL_FORMAT_INDEX:
				if (!empty($request))
					$url.='index.php/'.$requestpath;
				break;

			case QA_URL_FORMAT_NEAT:
				$url.=$requestpath;
				break;

			case QA_URL_FORMAT_PARAM:
				if (!empty($request))
					$paramsextra='?qa='.$requestpath;
				break;

			default:
				$url.='index.php';

			case QA_URL_FORMAT_PARAMS:
				if (!empty($request))
					foreach ($requestparts as $partindex => $requestpart)
						$paramsextra.=(strlen($paramsextra) ? '&' : '?').'qa'.($partindex ? ('_'.$partindex) : '').'='.$requestpart;
				break;
		}

		if (isset($params))
			foreach ($params as $key => $value)
				$paramsextra.=(strlen($paramsextra) ? '&' : '?').urlencode($key).'='.urlencode((string)$value);

		return $url.$paramsextra.( empty($anchor) ? '' : '#'.urlencode($anchor) );
	}


	function qa_path_html($request, $params=null, $rooturl=null, $neaturls=null, $anchor=null)
/*
	Return HTML representation of relative URI path for $request - see qa_path() for other parameters
*/
	{
		return qa_html(qa_path($request, $params, $rooturl, $neaturls, $anchor));
	}


	function qa_path_absolute($request, $params=null, $anchor=null)
/*
	Return the absolute URI for $request - see qa_path() for other parameters
*/
	{
		return qa_path($request, $params, qa_opt('site_url'), null, $anchor);
	}


	function qa_q_request($questionid, $title)
/*
	Return the Q2A request for question $questionid, and make it search-engine friendly based on $title, which is
	shortened if necessary by removing shorter words which are generally less meaningful.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		require_once QA_INCLUDE_DIR.'app/options.php';
		require_once QA_INCLUDE_DIR.'util/string.php';

		$title=qa_block_words_replace($title, qa_get_block_words_preg());

		$words=qa_string_to_words($title, true, false, false);

		$wordlength=array();
		foreach ($words as $index => $word)
			$wordlength[$index]=qa_strlen($word);

		$remaining=qa_opt('q_urls_title_length');

		if (array_sum($wordlength)>$remaining) {
			arsort($wordlength, SORT_NUMERIC); // sort with longest words first

			foreach ($wordlength as $index => $length) {
				if ($remaining>0)
					$remaining-=$length;
				else
					unset($words[$index]);
			}
		}

		$title=implode('-', $words);
		if (qa_opt('q_urls_remove_accents'))
			$title=qa_string_remove_accents($title);

		return (int)$questionid.'/'.$title;
	}


	function qa_anchor($basetype, $postid)
/*
	Return the HTML anchor that should be used for post $postid with $basetype (Q/A/C)
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return strtolower($basetype).$postid; // used to be $postid only but this violated HTML spec
	}


	function qa_q_path($questionid, $title, $absolute=false, $showtype=null, $showid=null)
/*
	Return the URL for question $questionid with $title, possibly using $absolute URLs.
	To link to a specific answer or comment in a question, set $showtype and $showid accordingly.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		if ( (($showtype=='Q') || ($showtype=='A') || ($showtype=='C')) && isset($showid))  {
			$params=array('show' => $showid); // due to pagination
			$anchor=qa_anchor($showtype, $showid);

		} else {
			$params=null;
			$anchor=null;
		}

		return qa_path(qa_q_request($questionid, $title), $params, $absolute ? qa_opt('site_url') : null, null, $anchor);
	}


	function qa_q_path_html($questionid, $title, $absolute=false, $showtype=null, $showid=null)
/*
	Return the HTML representation of the URL for $questionid - other parameters as for qa_q_path()
*/
	{
		return qa_html(qa_q_path($questionid, $title, $absolute, $showtype, $showid));
	}


	function qa_feed_request($feed)
/*
	Return the request for the specified $feed
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		return 'feed/'.$feed.'.rss';
	}


	function qa_self_html()
/*
	Return an HTML-ready relative URL for the current page, preserving GET parameters - this is useful for action="..." in HTML forms
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_used_url_format;

		return qa_path_html(qa_request(), $_GET, null, $qa_used_url_format);
	}


	function qa_path_form_html($request, $params=null, $rooturl=null, $neaturls=null, $anchor=null)
/*
	Return HTML for hidden fields to insert into a <form method="get"...> on the page.
	This is needed because any parameters on the URL will be lost when the form is submitted.
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		$path=qa_path($request, $params, $rooturl, $neaturls, $anchor);
		$formhtml='';

		$questionpos=strpos($path, '?');
		if (is_numeric($questionpos)) {
			$params=explode('&', substr($path, $questionpos+1));

			foreach ($params as $param)
				if (preg_match('/^([^\=]*)(\=(.*))?$/', $param, $matches))
					$formhtml.='<input type="hidden" name="'.qa_html(urldecode($matches[1])).'" value="'.qa_html(urldecode(@$matches[3])).'"/>';
		}

		return $formhtml;
	}


	function qa_redirect($request, $params=null, $rooturl=null, $neaturls=null, $anchor=null)
/*
	Redirect the user's web browser to $request and then we're done - see qa_path() for other parameters
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		qa_redirect_raw(qa_path($request, $params, $rooturl, $neaturls, $anchor));
	}


	function qa_redirect_raw($url)
/*
	Redirect the user's web browser to page $path which is already a URL
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		header('Location: '.$url);
		qa_exit('redirect');
	}


//	General utilities

	function qa_retrieve_url($url)
/*
	Return the contents of remote $url, using file_get_contents() if possible, otherwise curl functions
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		$contents=@file_get_contents($url);

		if ((!strlen($contents)) && function_exists('curl_exec')) { // try curl as a backup (if allow_url_fopen not set)
			$curl=curl_init($url);
			curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
			curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
			$contents=@curl_exec($curl);
			curl_close($curl);
		}

		return $contents;
	}


	function qa_opt($name, $value=null)
/*
	Shortcut to get or set an option value without specifying database
*/
	{
		global $qa_options_cache;

		if ((!isset($value)) && isset($qa_options_cache[$name]))
			return $qa_options_cache[$name]; // quick shortcut to reduce calls to qa_get_options()

		require_once QA_INCLUDE_DIR.'app/options.php';

		if (isset($value))
			qa_set_option($name, $value);

		$options=qa_get_options(array($name));

		return $options[$name];
	}

	/**
	 * Simple method to output a preformatted variable
	 */
	function qa_debug($var)
	{
		echo "\n" . '<pre style="padding: 10px; background-color: #eee; color: #444; font-size: 11px; text-align: left">';
		echo $var === null ? 'NULL' : print_r($var, true);
		echo '</pre>' . "\n";
	}


//	Event and process stage reporting

	function qa_suspend_event_reports($suspend=true)
/*
	Suspend the reporting of events to event modules via qa_report_event(...) if $suspend is
	true, otherwise reinstate it. A counter is kept to allow multiple calls.
*/
	{
		global $qa_event_reports_suspended;

		$qa_event_reports_suspended+=($suspend ? 1 : -1);
	}


	function qa_report_event($event, $userid, $handle, $cookieid, $params=array())
/*
	Send a notification of event $event by $userid, $handle and $cookieid to all event modules, with extra $params
*/
	{
		if (qa_to_override(__FUNCTION__)) { $args=func_get_args(); return qa_call_override(__FUNCTION__, $args); }

		global $qa_event_reports_suspended;

		if ($qa_event_reports_suspended>0)
			return;

		$eventmodules=qa_load_modules_with('event', 'process_event');
		foreach ($eventmodules as $eventmodule)
			$eventmodule->process_event($event, $userid, $handle, $cookieid, $params);
	}


	function qa_report_process_stage($method) // can have extra params
	{
		global $qa_process_reports_suspended;

		if (@$qa_process_reports_suspended)
			return;

		$qa_process_reports_suspended=true; // prevent loop, e.g. because of an error

		$args=func_get_args();
		$args=array_slice($args, 1);

		$processmodules=qa_load_modules_with('process', $method);
		foreach ($processmodules as $processmodule)
			call_user_func_array(array($processmodule, $method), $args);

		$qa_process_reports_suspended=null;
	}


/*
	Omit PHP closing tag to help avoid accidental output
*/