Make envCheckGraphics use locateExecutable(). Move path stuff to a single method

[mediawiki.git] / includes / installer / Installer.php

<?php
/**
 * Base code for MediaWiki installer.
 *
 * @file
 * @ingroup Deployment
 */

/**
 * This documentation group collects source code files with deployment functionality.
 *
 * @defgroup Deployment Deployment
 */

/**
 * Base installer class.
 *
 * This class provides the base for installation and update functionality
 * for both MediaWiki core and extensions.
 *
 * @ingroup Deployment
 * @since 1.17
 */
abstract class Installer {

        /**
         * TODO: make protected?
         *
         * @var array
         */
        public $settings;

        /**
         * Cached DB installer instances, access using getDBInstaller().
         *
         * @var array
         */
        protected $dbInstallers = array();

        /**
         * Minimum memory size in MB.
         *
         * @var integer
         */
        protected $minMemorySize = 50;

        /**
         * Cached Title, used by parse().
         *
         * @var Title
         */
        protected $parserTitle;

        /**
         * Cached ParserOptions, used by parse().
         *
         * @var ParserOptions
         */
        protected $parserOptions;

        /**
         * Known database types. These correspond to the class names <type>Installer,
         * and are also MediaWiki database types valid for $wgDBtype.
         *
         * To add a new type, create a <type>Installer class and a Database<type>
         * class, and add a config-type-<type> message to MessagesEn.php.
         *
         * @var array
         */
        protected static $dbTypes = array(
                'mysql',
                'postgres',
                'sqlite',
        );

        /**
         * A list of environment check methods called by doEnvironmentChecks().
         * These may output warnings using showMessage(), and/or abort the
         * installation process by returning false.
         *
         * @var array
         */
        protected $envChecks = array(
                'envLatestVersion',
                'envCheckDB',
                'envCheckRegisterGlobals',
                'envCheckMagicQuotes',
                'envCheckMagicSybase',
                'envCheckMbstring',
                'envCheckZE1',
                'envCheckSafeMode',
                'envCheckXML',
                'envCheckPCRE',
                'envCheckMemory',
                'envCheckCache',
                'envCheckDiff3',
                'envCheckGraphics',
                'envCheckPath',
                'envCheckWriteableDir',
                'envCheckExtension',
                'envCheckShellLocale',
                'envCheckUploadsDirectory',
                'envCheckLibicu'
        );

        /**
         * UI interface for displaying a short message
         * The parameters are like parameters to wfMsg().
         * The messages will be in wikitext format, which will be converted to an
         * output format such as HTML or text before being sent to the user.
         */
        public abstract function showMessage( $msg /*, ... */ );

        /**
         * Constructor, always call this from child classes.
         */
        public function __construct() {
                // Disable the i18n cache and LoadBalancer
                Language::getLocalisationCache()->disableBackend();
                LBFactory::disableBackend();
        }

        /**
         * Get a list of known DB types.
         */
        public static function getDBTypes() {
                return self::$dbTypes;
        }

        /**
         * Do initial checks of the PHP environment. Set variables according to
         * the observed environment.
         *
         * It's possible that this may be called under the CLI SAPI, not the SAPI
         * that the wiki will primarily run under. In that case, the subclass should
         * initialise variables such as wgScriptPath, before calling this function.
         *
         * Under the web subclass, it can already be assumed that PHP 5+ is in use
         * and that sessions are working.
         *
         * @return boolean
         */
        public function doEnvironmentChecks() {
                $this->showMessage( 'config-env-php', phpversion() );

                $good = true;

                foreach ( $this->envChecks as $check ) {
                        $status = $this->$check();
                        if ( $status === false ) {
                                $good = false;
                        }
                }

                $this->setVar( '_Environment', $good );

                if ( $good ) {
                        $this->showMessage( 'config-env-good' );
                } else {
                        $this->showMessage( 'config-env-bad' );
                }

                return $good;
        }

        /**
         * Set a MW configuration variable, or internal installer configuration variable.
         *
         * @param $name String
         * @param $value Mixed
         */
        public function setVar( $name, $value ) {
                $this->settings[$name] = $value;
        }

        /**
         * Get an MW configuration variable, or internal installer configuration variable.
         * The defaults come from $GLOBALS (ultimately DefaultSettings.php).
         * Installer variables are typically prefixed by an underscore.
         *
         * @param $name String
         * @param $default Mixed
         *
         * @return mixed
         */
        public function getVar( $name, $default = null ) {
                if ( !isset( $this->settings[$name] ) ) {
                        return $default;
                } else {
                        return $this->settings[$name];
                }
        }

        /**
         * Get an instance of DatabaseInstaller for the specified DB type.
         *
         * @param $type Mixed: DB installer for which is needed, false to use default.
         *
         * @return DatabaseInstaller
         */
        public function getDBInstaller( $type = false ) {
                if ( !$type ) {
                        $type = $this->getVar( 'wgDBtype' );
                }

                $type = strtolower( $type );

                if ( !isset( $this->dbInstallers[$type] ) ) {
                        $class = ucfirst( $type ). 'Installer';
                        $this->dbInstallers[$type] = new $class( $this );
                }

                return $this->dbInstallers[$type];
        }

        /**
         * Determine if LocalSettings exists. If it does, return an appropriate
         * status for whether we should can upgrade or not.
         *
         * @return Status
         */
        public function getLocalSettingsStatus() {
                global $IP;

                $status = Status::newGood();

                wfSuppressWarnings();
                $ls = file_exists( "$IP/LocalSettings.php" );
                wfRestoreWarnings();

                if( $ls ) {
                        if( $this->getDBInstaller()->needsUpgrade() ) {
                                $status->warning( 'config-localsettings-upgrade' );
                        }
                        else {
                                $status->fatal( 'config-localsettings-noupgrade' );
                        }
                }

                return $status;
        }

        /**
         * Get a fake password for sending back to the user in HTML.
         * This is a security mechanism to avoid compromise of the password in the
         * event of session ID compromise.
         *
         * @param $realPassword String
         *
         * @return string
         */
        public function getFakePassword( $realPassword ) {
                return str_repeat( '*', strlen( $realPassword ) );
        }

        /**
         * Set a variable which stores a password, except if the new value is a
         * fake password in which case leave it as it is.
         *
         * @param $name String
         * @param $value Mixed
         */
        public function setPassword( $name, $value ) {
                if ( !preg_match( '/^\*+$/', $value ) ) {
                        $this->setVar( $name, $value );
                }
        }

        /**
         * On POSIX systems return the primary group of the webserver we're running under.
         * On other systems just returns null.
         *
         * This is used to advice the user that he should chgrp his config/data/images directory as the
         * webserver user before he can install.
         *
         * Public because SqliteInstaller needs it, and doesn't subclass Installer.
         *
         * @return mixed
         */
        public static function maybeGetWebserverPrimaryGroup() {
                if ( !function_exists( 'posix_getegid' ) || !function_exists( 'posix_getpwuid' ) ) {
                        # I don't know this, this isn't UNIX.
                        return null;
                }

                # posix_getegid() *not* getmygid() because we want the group of the webserver,
                # not whoever owns the current script.
                $gid = posix_getegid();
                $getpwuid = posix_getpwuid( $gid );
                $group = $getpwuid['name'];

                return $group;
        }

        /**
         * Convert wikitext $text to HTML.
         *
         * This is potentially error prone since many parser features require a complete
         * installed MW database. The solution is to just not use those features when you
         * write your messages. This appears to work well enough. Basic formatting and
         * external links work just fine.
         *
         * But in case a translator decides to throw in a #ifexist or internal link or
         * whatever, this function is guarded to catch attempted DB access and to present
         * some fallback text.
         *
         * @param $text String
         * @param $lineStart Boolean
         * @return String
         */
        public function parse( $text, $lineStart = false ) {
                global $wgParser;

                try {
                        $out = $wgParser->parse( $text, $this->parserTitle, $this->parserOptions, $lineStart );
                        $html = $out->getText();
                } catch ( DBAccessError $e ) {
                        $html = '<!--DB access attempted during parse-->  ' . htmlspecialchars( $text );

                        if ( !empty( $this->debug ) ) {
                                $html .= "<!--\n" . $e->getTraceAsString() . "\n-->";
                        }
                }

                return $html;
        }

        /**
         * TODO: document
         *
         * @param $installer DatabaseInstaller
         *
         * @return Status
         */
        public function installDatabase( DatabaseInstaller &$installer ) {
                if( !$installer ) {
                        $type = $this->getVar( 'wgDBtype' );
                        $status = Status::newFatal( "config-no-db", $type );
                } else {
                        $status = $installer->setupDatabase();
                }

                return $status;
        }

        /**
         * TODO: document
         *
         * @param $installer DatabaseInstaller
         *
         * @return Status
         */
        public function installTables( DatabaseInstaller &$installer ) {
                $status = $installer->createTables();

                if( $status->isOK() ) {
                        LBFactory::enableBackend();
                }

                return $status;
        }

        /**
         * TODO: document
         *
         * @param $installer DatabaseInstaller
         *
         * @return Status
         */
        public function installInterwiki( DatabaseInstaller &$installer ) {
                return $installer->populateInterwikiTable();
        }

        /**
         * Exports all wg* variables stored by the installer into global scope.
         */
        public function exportVars() {
                foreach ( $this->settings as $name => $value ) {
                        if ( substr( $name, 0, 2 ) == 'wg' ) {
                                $GLOBALS[$name] = $value;
                        }
                }
        }

        /**
         * Get an array of likely places we can find executables. Check a bunch
         * of known Unix-like defaults, as well as the PATH environment variable
         * (which should maybe make it work for Windows?)
         *
         * @return Array
         */
        protected function getPossibleBinPaths() {
                return array_merge(
                        array( '/usr/bin', '/usr/local/bin', '/opt/csw/bin',
                                '/usr/gnu/bin', '/usr/sfw/bin', '/sw/bin', '/opt/local/bin' ),
                        explode( PATH_SEPARATOR, getenv( 'PATH' ) )
                );
        }

        /**
         * Check if we're installing the latest version.
         */
        public function envLatestVersion() {
                global $wgVersion;

                $repository = wfGetRepository();
                $currentVersion = $repository->getLatestCoreVersion();

                $this->setVar( '_ExternalHTTP', true );

                if ( $currentVersion === false ) {
                        # For when the request is successful but there's e.g. some silly man in
                        # the middle firewall blocking us, e.g. one of those annoying airport ones
                        $this->showMessage( 'config-env-latest-can-not-check', $repository->getLocation() );
                        return;
                }

                if( version_compare( $wgVersion, $currentVersion, '<' ) ) {
                        $this->showMessage( 'config-env-latest-old' );
                        // FIXME: this only works for the web installer!
                        $this->showHelpBox( 'config-env-latest-help', $wgVersion, $currentVersion );
                } elseif( version_compare( $wgVersion, $currentVersion, '>' ) ) {
                        $this->showMessage( 'config-env-latest-new' );
                }

                $this->showMessage( 'config-env-latest-ok' );
        }

        /**
         * Environment check for DB types.
         */
        public function envCheckDB() {
                global $wgLang;

                $compiledDBs = array();
                $goodNames = array();
                $allNames = array();

                foreach ( self::getDBTypes() as $name ) {
                        $db = $this->getDBInstaller( $name );
                        $readableName = wfMsg( 'config-type-' . $name );

                        if ( $db->isCompiled() ) {
                                $compiledDBs[] = $name;
                                $goodNames[] = $readableName;
                        }

                        $allNames[] = $readableName;
                }

                $this->setVar( '_CompiledDBs', $compiledDBs );

                if ( !$compiledDBs ) {
                        $this->showMessage( 'config-no-db' );
                        // FIXME: this only works for the web installer!
                        $this->showHelpBox( 'config-no-db-help', $wgLang->commaList( $allNames ) );
                        return false;
                }

                $this->showMessage( 'config-have-db', $wgLang->listToText( $goodNames ), count( $goodNames ) );

                // Check for FTS3 full-text search module
                $sqlite = $this->getDBInstaller( 'sqlite' );
                if ( $sqlite->isCompiled() ) {
                        $db = new DatabaseSqliteStandalone( ':memory:' );
                        $this->showMessage( $db->getFulltextSearchModule() == 'FTS3'
                                ? 'config-have-fts3'
                                : 'config-no-fts3'
                        );
                }
        }

        /**
         * Environment check for register_globals.
         */
        public function envCheckRegisterGlobals() {
                if( wfIniGetBool( "magic_quotes_runtime" ) ) {
                        $this->showMessage( 'config-register-globals' );
                }
        }

        /**
         * Environment check for magic_quotes_runtime.
         */
        public function envCheckMagicQuotes() {
                if( wfIniGetBool( "magic_quotes_runtime" ) ) {
                        $this->showMessage( 'config-magic-quotes-runtime' );
                        return false;
                }
        }

        /**
         * Environment check for magic_quotes_sybase.
         */
        public function envCheckMagicSybase() {
                if ( wfIniGetBool( 'magic_quotes_sybase' ) ) {
                        $this->showMessage( 'config-magic-quotes-sybase' );
                        return false;
                }
        }

        /**
         * Environment check for mbstring.func_overload.
         */
        public function envCheckMbstring() {
                if ( wfIniGetBool( 'mbstring.func_overload' ) ) {
                        $this->showMessage( 'config-mbstring' );
                        return false;
                }
        }

        /**
         * Environment check for zend.ze1_compatibility_mode.
         */
        public function envCheckZE1() {
                if ( wfIniGetBool( 'zend.ze1_compatibility_mode' ) ) {
                        $this->showMessage( 'config-ze1' );
                        return false;
                }
        }

        /**
         * Environment check for safe_mode.
         */
        public function envCheckSafeMode() {
                if ( wfIniGetBool( 'safe_mode' ) ) {
                        $this->setVar( '_SafeMode', true );
                        $this->showMessage( 'config-safe-mode' );
                }
        }

        /**
         * Environment check for the XML module.
         */
        public function envCheckXML() {
                if ( !function_exists( "utf8_encode" ) ) {
                        $this->showMessage( 'config-xml-bad' );
                        return false;
                }
                $this->showMessage( 'config-xml-good' );
        }

        /**
         * Environment check for the PCRE module.
         */
        public function envCheckPCRE() {
                if ( !function_exists( 'preg_match' ) ) {
                        $this->showMessage( 'config-pcre' );
                        return false;
                }
        }

        /**
         * Environment check for available memory.
         */
        public function envCheckMemory() {
                $limit = ini_get( 'memory_limit' );

                if ( !$limit || $limit == -1 ) {
                        $this->showMessage( 'config-memory-none' );
                        return true;
                }

                $n = intval( $limit );

                if( preg_match( '/^([0-9]+)[Mm]$/', trim( $limit ), $m ) ) {
                        $n = intval( $m[1] * ( 1024 * 1024 ) );
                }

                if( $n < $this->minMemorySize * 1024 * 1024 ) {
                        $newLimit = "{$this->minMemorySize}M";

                        if( ini_set( "memory_limit", $newLimit ) === false ) {
                                $this->showMessage( 'config-memory-bad', $limit );
                        } else {
                                $this->showMessage( 'config-memory-raised', $limit, $newLimit );
                                $this->setVar( '_RaiseMemory', true );
                        }
                } else {
                        $this->showMessage( 'config-memory-ok', $limit );
                }
        }

        /**
         * Environment check for compiled object cache types.
         */
        public function envCheckCache() {
                $caches = array();

                foreach ( $this->objectCaches as $name => $function ) {
                        if ( function_exists( $function ) ) {
                                $caches[$name] = true;
                                $this->showMessage( 'config-' . $name );
                        }
                }

                if ( !$caches ) {
                        $this->showMessage( 'config-no-cache' );
                }

                $this->setVar( '_Caches', $caches );
        }

        /**
         * Search for GNU diff3.
         */
        public function envCheckDiff3() {
                $names = array( "gdiff3", "diff3", "diff3.exe" );
                $versionInfo = array( '$1 --version 2>&1', 'diff3 (GNU diffutils)' );

                $haveDiff3 = false;

                foreach ( $this->getPossibleBinPaths() as $path ) {
                        $exe = $this->locateExecutable( $path, $names, $versionInfo );

                        if ($exe !== false) {
                                $this->setVar( 'wgDiff3', $exe );
                                $haveDiff3 = true;
                                break;
                        }
                }

                if ( $haveDiff3 ) {
                        $this->showMessage( 'config-diff3-good', $exe );
                } else {
                        $this->setVar( 'wgDiff3', false );
                        $this->showMessage( 'config-diff3-bad' );
                }
        }

        /**
         * Environment check for ImageMagick and GD.
         */
        public function envCheckGraphics() {
                $names = array( 'convert', 'convert.exe' );
                $haveConvert = false;

                foreach ( $this->getPossibleBinPaths() as $path ) {
                        $exe = $this->locateExecutable( $path, $names );

                        if ($exe !== false) {
                                $this->setVar( 'wgImageMagickConvertCommand', $exe );
                                $haveConvert = true;
                                break;
                        }
                }

                if ( $haveConvert ) {
                        $this->showMessage( 'config-imagemagick', $exe );
                        return true;
                } elseif ( function_exists( 'imagejpeg' ) ) {
                        $this->showMessage( 'config-gd' );
                        return true;
                } else {
                        $this->showMessage( 'no-scaling' );
                }
        }

        /**
         * Environment check for setting $IP and $wgScriptPath.
         */
        public function envCheckPath() {
                global $IP;
                $IP = dirname( dirname( dirname( __FILE__ ) ) );

                $this->setVar( 'IP', $IP );
                $this->showMessage( 'config-dir', $IP );

                // PHP_SELF isn't available sometimes, such as when PHP is CGI but
                // cgi.fix_pathinfo is disabled. In that case, fall back to SCRIPT_NAME
                // to get the path to the current script... hopefully it's reliable. SIGH
                if ( !empty( $_SERVER['PHP_SELF'] ) ) {
                        $path = $_SERVER['PHP_SELF'];
                } elseif ( !empty( $_SERVER['SCRIPT_NAME'] ) ) {
                        $path = $_SERVER['SCRIPT_NAME'];
                } elseif ( $this->getVar( 'wgScriptPath' ) ) {
                        // Some kind soul has set it for us already (e.g. debconf)
                        return true;
                } else {
                        $this->showMessage( 'config-no-uri' );
                        return false;
                }

                $uri = preg_replace( '{^(.*)/config.*$}', '$1', $path );
                $this->setVar( 'wgScriptPath', $uri );
                $this->showMessage( 'config-uri', $uri );
        }

        /**
         * Environment check for writable config/ directory.
         */
        public function envCheckWriteableDir() {
                $ipDir = $this->getVar( 'IP' );
                $configDir = $ipDir . '/config';

                if( !is_writeable( $configDir ) ) {
                        $webserverGroup = self::maybeGetWebserverPrimaryGroup();

                        if ( $webserverGroup !== null ) {
                                $this->showMessage( 'config-dir-not-writable-group', $ipDir, $webserverGroup );
                        } else {
                                $this->showMessage( 'config-dir-not-writable-nogroup', $ipDir, $webserverGroup );
                        }

                        return false;
                }
        }

        /**
         * Environment check for setting the preferred PHP file extension.
         */
        public function envCheckExtension() {
                // FIXME: detect this properly
                if ( defined( 'MW_INSTALL_PHP5_EXT' ) ) {
                        $ext = 'php5';
                } else {
                        $ext = 'php';
                }

                $this->setVar( 'wgScriptExtension', ".$ext" );
                $this->showMessage( 'config-file-extension', $ext );
        }

        /**
         * TODO: document
         */
        public function envCheckShellLocale() {
                # Give up now if we're in safe mode or open_basedir.
                # It's theoretically possible but tricky to work with.
                if ( wfIniGetBool( "safe_mode" ) || ini_get( 'open_basedir' ) || !function_exists( 'exec' ) ) {
                        return true;
                }

                $os = php_uname( 's' );
                $supported = array( 'Linux', 'SunOS', 'HP-UX' ); # Tested these

                if ( !in_array( $os, $supported ) ) {
                        return true;
                }

                # Get a list of available locales.
                $lines = $ret = false;
                exec( '/usr/bin/locale -a', $lines, $ret );

                if ( $ret ) {
                        return true;
                }

                $lines = wfArrayMap( 'trim', $lines );
                $candidatesByLocale = array();
                $candidatesByLang = array();

                foreach ( $lines as $line ) {
                        if ( $line === '' ) {
                                continue;
                        }

                        if ( !preg_match( '/^([a-zA-Z]+)(_[a-zA-Z]+|)\.(utf8|UTF-8)(@[a-zA-Z_]*|)$/i', $line, $m ) ) {
                                continue;
                        }

                        list( $all, $lang, $territory, $charset, $modifier ) = $m;

                        $candidatesByLocale[$m[0]] = $m;
                        $candidatesByLang[$lang][] = $m;
                }

                # Try the current value of LANG.
                if ( isset( $candidatesByLocale[ getenv( 'LANG' ) ] ) ) {
                        $this->setVar( 'wgShellLocale', getenv( 'LANG' ) );
                        $this->showMessage( 'config-shell-locale', getenv( 'LANG' ) );
                        return true;
                }

                # Try the most common ones.
                $commonLocales = array( 'en_US.UTF-8', 'en_US.utf8', 'de_DE.UTF-8', 'de_DE.utf8' );
                foreach ( $commonLocales as $commonLocale ) {
                        if ( isset( $candidatesByLocale[$commonLocale] ) ) {
                                $this->setVar( 'wgShellLocale', $commonLocale );
                                $this->showMessage( 'config-shell-locale', $commonLocale );
                                return true;
                        }
                }

                # Is there an available locale in the Wiki's language?
                $wikiLang = $this->getVar( 'wgLanguageCode' );

                if ( isset( $candidatesByLang[$wikiLang] ) ) {
                        $m = reset( $candidatesByLang[$wikiLang] );
                        $this->setVar( 'wgShellLocale', $m[0] );
                        $this->showMessage( 'config-shell-locale', $m[0] );
                        return true;
                }

                # Are there any at all?
                if ( count( $candidatesByLocale ) ) {
                        $m = reset( $candidatesByLocale );
                        $this->setVar( 'wgShellLocale', $m[0] );
                        $this->showMessage( 'config-shell-locale', $m[0] );
                        return true;
                }

                # Give up.
                return true;
        }

        /**
         * TODO: document
         */
        public function envCheckUploadsDirectory() {
                global $IP, $wgServer;

                $dir = $IP . '/images/';
                $url = $wgServer . $this->getVar( 'wgScriptPath' ) . '/images/';
                $safe = !$this->dirIsExecutable( $dir, $url );

                if ( $safe ) {
                        $this->showMessage( 'config-uploads-safe' );
                } else {
                        $this->showMessage( 'config-uploads-not-safe', $dir );
                }
        }

        /**
         * Convert a hex string representing a Unicode code point to that code point.
         * @param $c String
         * @return string
         */
        protected function unicodeChar( $c ) {
                $c = hexdec($c);
                if ($c <= 0x7F) {
                        return chr($c);
                } else if ($c <= 0x7FF) {
                        return chr(0xC0 | $c >> 6) . chr(0x80 | $c & 0x3F);
                } else if ($c <= 0xFFFF) {
                        return chr(0xE0 | $c >> 12) . chr(0x80 | $c >> 6 & 0x3F)
                                . chr(0x80 | $c & 0x3F);
                } else if ($c <= 0x10FFFF) {
                        return chr(0xF0 | $c >> 18) . chr(0x80 | $c >> 12 & 0x3F)
                                . chr(0x80 | $c >> 6 & 0x3F)
                                . chr(0x80 | $c & 0x3F);
                } else {
                        return false;
                }
        }


        /**
         * Check the libicu version
         */
        public function envCheckLibicu() {
                $utf8 = function_exists( 'utf8_normalize' );
                $intl = function_exists( 'normalizer_normalize' );

                /**
                 * This needs to be updated something that the latest libicu
                 * will properly normalize.  This normalization was found at
                 * http://www.unicode.org/versions/Unicode5.2.0/#Character_Additions
                 * Note that we use the hex representation to create the code
                 * points in order to avoid any Unicode-destroying during transit.
                 */
                $not_normal_c = $this->unicodeChar("FA6C");
                $normal_c = $this->unicodeChar("242EE");

                $useNormalizer = 'php';
                $needsUpdate = false;

                /**
                 * We're going to prefer the pecl extension here unless
                 * utf8_normalize is more up to date.
                 */
                if( $utf8 ) {
                        $useNormalizer = 'utf8';
                        $utf8 = utf8_normalize( $not_normal_c, UNORM_NFC );
                        if ( $utf8 !== $normal_c ) $needsUpdate = true;
                }
                if( $intl ) {
                        $useNormalizer = 'intl';
                        $intl = normalizer_normalize( $not_normal_c, Normalizer::FORM_C );
                        if ( $intl !== $normal_c ) $needsUpdate = true;
                }

                // Uses messages 'config-unicode-using-php', 'config-unicode-using-utf8', 'config-unicode-using-intl'
                $this->showMessage( 'config-unicode-using-' . $useNormalizer );
                if( $useNormalizer === 'php' ) {
                        $this->showMessage( 'config-unicode-pure-php-warning' );
                } elseif( $needsUpdate ) {
                        $this->showMessage( 'config-unicode-update-warning' );
                }
        }


        /**
         * Search a path for any of the given executable names. Returns the
         * executable name if found. Also checks the version string returned
         * by each executable.
         *
         * Used only by environment checks.
         *
         * @param $path String: path to search
         * @param $names Array of executable names
         * @param $versionInfo Boolean false or array with two members:
         *               0 => Command to run for version check, with $1 for the path
         *               1 => String to compare the output with
         *
         * If $versionInfo is not false, only executables with a version
         * matching $versionInfo[1] will be returned.
         */
        protected function locateExecutable( $path, $names, $versionInfo = false ) {
                if ( !is_array( $names ) ) {
                        $names = array( $names );
                }

                foreach ( $names as $name ) {
                        $command = "$path/$name";

                        wfSuppressWarnings();
                        $file_exists = file_exists( $command );
                        wfRestoreWarnings();

                        if ( $file_exists ) {
                                if ( !$versionInfo ) {
                                        return $command;
                                }

                                $file = str_replace( '$1', $command, $versionInfo[0] );

                                # Should maybe be wfShellExec( $file), but runs into a ulimit, see
                                # http://www.mediawiki.org/w/index.php?title=New-installer_issues&diff=prev&oldid=335456
                                if ( strstr( `$file`, $versionInfo[1]) !== false ) {
                                        return $command;
                                }
                        }
                }

                return false;
        }

        /**
         * Checks if scripts located in the given directory can be executed via the given URL.
         *
         * Used only by environment checks.
         */
        public function dirIsExecutable( $dir, $url ) {
                $scriptTypes = array(
                        'php' => array(
                                "<?php echo 'ex' . 'ec';",
                                "#!/var/env php5\n<?php echo 'ex' . 'ec';",
                        ),
                );

                // it would be good to check other popular languages here, but it'll be slow.

                wfSuppressWarnings();

                foreach ( $scriptTypes as $ext => $contents ) {
                        foreach ( $contents as $source ) {
                                $file = 'exectest.' . $ext;

                                if ( !file_put_contents( $dir . $file, $source ) ) {
                                        break;
                                }

                                $text = Http::get( $url . $file );
                                unlink( $dir . $file );

                                if ( $text == 'exec' ) {
                                        wfRestoreWarnings();
                                        return $ext;
                                }
                        }
                }

                wfRestoreWarnings();

                return false;
        }

}