Installer.php

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<?php
abstract class Installer {

        // This is the absolute minimum PHP version we can support
        const MINIMUM_PHP_VERSION = '5.3.2';

        protected $settings;

        protected $dbInstallers = array();

        protected $minMemorySize = 50;

        protected $parserTitle;

        protected $parserOptions;

        protected static $dbTypes = array(
                'mysql',
                'postgres',
                'oracle',
                'sqlite',
                'ibm_db2',
        );

        protected $envChecks = array(
                'envCheckDB',
                'envCheckRegisterGlobals',
                'envCheckBrokenXML',
                'envCheckPHP531',
                'envCheckMagicQuotes',
                'envCheckMagicSybase',
                'envCheckMbstring',
                'envCheckZE1',
                'envCheckSafeMode',
                'envCheckXML',
                'envCheckPCRE',
                'envCheckMemory',
                'envCheckCache',
                'envCheckModSecurity',
                'envCheckDiff3',
                'envCheckGraphics',
                'envCheckServer',
                'envCheckPath',
                'envCheckExtension',
                'envCheckShellLocale',
                'envCheckUploadsDirectory',
                'envCheckLibicu',
                'envCheckSuhosinMaxValueLength',
                'envCheckCtype',
        );

        protected $defaultVarNames = array(
                'wgSitename',
                'wgPasswordSender',
                'wgLanguageCode',
                'wgRightsIcon',
                'wgRightsText',
                'wgRightsUrl',
                'wgMainCacheType',
                'wgEnableEmail',
                'wgEnableUserEmail',
                'wgEnotifUserTalk',
                'wgEnotifWatchlist',
                'wgEmailAuthentication',
                'wgDBtype',
                'wgDiff3',
                'wgImageMagickConvertCommand',
                'IP',
                'wgServer',
                'wgScriptPath',
                'wgScriptExtension',
                'wgMetaNamespace',
                'wgDeletedDirectory',
                'wgEnableUploads',
                'wgLogo',
                'wgShellLocale',
                'wgSecretKey',
                'wgUseInstantCommons',
                'wgUpgradeKey',
                'wgDefaultSkin',
                'wgResourceLoaderMaxQueryLength',
        );

        protected $internalDefaults = array(
                '_UserLang' => 'en',
                '_Environment' => false,
                '_CompiledDBs' => array(),
                '_SafeMode' => false,
                '_RaiseMemory' => false,
                '_UpgradeDone' => false,
                '_InstallDone' => false,
                '_Caches' => array(),
                '_InstallPassword' => '',
                '_SameAccount' => true,
                '_CreateDBAccount' => false,
                '_NamespaceType' => 'site-name',
                '_AdminName' => '', // will be set later, when the user selects language
                '_AdminPassword' => '',
                '_AdminPassword2' => '',
                '_AdminEmail' => '',
                '_Subscribe' => false,
                '_SkipOptional' => 'continue',
                '_RightsProfile' => 'wiki',
                '_LicenseCode' => 'none',
                '_CCDone' => false,
                '_Extensions' => array(),
                '_MemCachedServers' => '',
                '_UpgradeKeySupplied' => false,
                '_ExistingDBSettings' => false,
        );

        private $installSteps = array();

        protected $extraInstallSteps = array();

        protected $objectCaches = array(
                'xcache' => 'xcache_get',
                'apc' => 'apc_fetch',
                'wincache' => 'wincache_ucache_get'
        );

        public $rightsProfiles = array(
                'wiki' => array(),
                'no-anon' => array(
                        '*' => array( 'edit' => false )
                ),
                'fishbowl' => array(
                        '*' => array(
                                'createaccount' => false,
                                'edit' => false,
                        ),
                ),
                'private' => array(
                        '*' => array(
                                'createaccount' => false,
                                'edit' => false,
                                'read' => false,
                        ),
                ),
        );

        public $licenses = array(
                'cc-by' => array(
                        'url' => 'http://creativecommons.org/licenses/by/3.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-by.png',
                ),
                'cc-by-sa' => array(
                        'url' => 'http://creativecommons.org/licenses/by-sa/3.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-by-sa.png',
                ),
                'cc-by-nc-sa' => array(
                        'url' => 'http://creativecommons.org/licenses/by-nc-sa/3.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-by-nc-sa.png',
                ),
                'cc-0' => array(
                        'url' => 'https://creativecommons.org/publicdomain/zero/1.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-0.png',
                ),
                'pd' => array(
                        'url' => '',
                        'icon' => '{$wgStylePath}/common/images/public-domain.png',
                ),
                'gfdl' => array(
                        'url' => 'http://www.gnu.org/copyleft/fdl.html',
                        'icon' => '{$wgStylePath}/common/images/gnu-fdl.png',
                ),
                'none' => array(
                        'url' => '',
                        'icon' => '',
                        'text' => ''
                ),
                'cc-choose' => array(
                        // Details will be filled in by the selector.
                        'url' => '',
                        'icon' => '',
                        'text' => '',
                ),
        );

        protected $mediaWikiAnnounceUrl = 'https://lists.wikimedia.org/mailman/subscribe/mediawiki-announce';

        protected $mediaWikiAnnounceLanguages = array(
                'ca', 'cs', 'da', 'de', 'en', 'es', 'et', 'eu', 'fi', 'fr', 'hr', 'hu',
                'it', 'ja', 'ko', 'lt', 'nl', 'no', 'pl', 'pt', 'pt-br', 'ro', 'ru',
                'sl', 'sr', 'sv', 'tr', 'uk'
        );

        public abstract function showMessage( $msg /*, ... */ );

        public abstract function showError( $msg /*, ... */ );

        public abstract function showStatusMessage( Status $status );

        public function __construct() {
                global $wgExtensionMessagesFiles, $wgUser;

                // Disable the i18n cache and LoadBalancer
                Language::getLocalisationCache()->disableBackend();
                LBFactory::disableBackend();

                // Load the installer's i18n file.
                $wgExtensionMessagesFiles['MediawikiInstaller'] =
                        __DIR__ . '/Installer.i18n.php';

                // Having a user with id = 0 safeguards us from DB access via User::loadOptions().
                $wgUser = User::newFromId( 0 );

                $this->settings = $this->internalDefaults;

                foreach ( $this->defaultVarNames as $var ) {
                        $this->settings[$var] = $GLOBALS[$var];
                }

                $compiledDBs = array();
                foreach ( self::getDBTypes() as $type ) {
                        $installer = $this->getDBInstaller( $type );

                        if ( !$installer->isCompiled() ) {
                                continue;
                        }
                        $compiledDBs[] = $type;

                        $defaults = $installer->getGlobalDefaults();

                        foreach ( $installer->getGlobalNames() as $var ) {
                                if ( isset( $defaults[$var] ) ) {
                                        $this->settings[$var] = $defaults[$var];
                                } else {
                                        $this->settings[$var] = $GLOBALS[$var];
                                }
                        }
                }
                $this->setVar( '_CompiledDBs', $compiledDBs );

                $this->parserTitle = Title::newFromText( 'Installer' );
                $this->parserOptions = new ParserOptions; // language will  be wrong :(
                $this->parserOptions->setEditSection( false );
        }

        public static function getDBTypes() {
                return self::$dbTypes;
        }

        public function doEnvironmentChecks() {
                $phpVersion = phpversion();
                if( version_compare( $phpVersion, self::MINIMUM_PHP_VERSION, '>=' ) ) {
                        $this->showMessage( 'config-env-php', $phpVersion );
                        $good = true;
                } else {
                        $this->showMessage( 'config-env-php-toolow', $phpVersion, self::MINIMUM_PHP_VERSION );
                        $good = false;
                }

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

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

                return $good ? Status::newGood() : Status::newFatal( 'config-env-bad' );
        }

        public function setVar( $name, $value ) {
                $this->settings[$name] = $value;
        }

        public function getVar( $name, $default = null ) {
                if ( !isset( $this->settings[$name] ) ) {
                        return $default;
                } else {
                        return $this->settings[$name];
                }
        }

        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];
        }

        public static function getExistingLocalSettings() {
                global $IP;

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

                if( !$_lsExists ) {
                        return false;
                }
                unset($_lsExists);

                require( "$IP/includes/DefaultSettings.php" );
                require( "$IP/LocalSettings.php" );
                if ( file_exists( "$IP/AdminSettings.php" ) ) {
                        require( "$IP/AdminSettings.php" );
                }
                return get_defined_vars();
        }

        public function getFakePassword( $realPassword ) {
                return str_repeat( '*', strlen( $realPassword ) );
        }

        public function setPassword( $name, $value ) {
                if ( !preg_match( '/^\*+$/', $value ) ) {
                        $this->setVar( $name, $value );
                }
        }

        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;
        }

        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;
        }

        public function getParserOptions() {
                return $this->parserOptions;
        }

        public function disableLinkPopups() {
                $this->parserOptions->setExternalLinkTarget( false );
        }

        public function restoreLinkPopups() {
                global $wgExternalLinkTarget;
                $this->parserOptions->setExternalLinkTarget( $wgExternalLinkTarget );
        }

        public function populateSiteStats( DatabaseInstaller $installer ) {
                $status = $installer->getConnection();
                if ( !$status->isOK() ) {
                        return $status;
                }
                $status->value->insert( 'site_stats', array(
                        'ss_row_id' => 1,
                        'ss_total_views' => 0,
                        'ss_total_edits' => 0,
                        'ss_good_articles' => 0,
                        'ss_total_pages' => 0,
                        'ss_users' => 0,
                        'ss_images' => 0 ),
                        __METHOD__, 'IGNORE' );
                return Status::newGood();
        }

        public function exportVars() {
                foreach ( $this->settings as $name => $value ) {
                        if ( substr( $name, 0, 2 ) == 'wg' ) {
                                $GLOBALS[$name] = $value;
                        }
                }
        }

        protected function envCheckDB() {
                global $wgLang;

                $allNames = array();

                foreach ( self::getDBTypes() as $name ) {
                        $allNames[] = wfMessage( "config-type-$name" )->text();
                }

                // cache initially available databases to make sure that everything will be displayed correctly
                // after a refresh on env checks page
                $databases = $this->getVar( '_CompiledDBs-preFilter' );
                if ( !$databases ) {
                        $databases = $this->getVar( '_CompiledDBs' );
                        $this->setVar( '_CompiledDBs-preFilter', $databases );
                }

                $databases = array_flip ( $databases );
                foreach ( array_keys( $databases ) as $db ) {
                        $installer = $this->getDBInstaller( $db );
                        $status = $installer->checkPrerequisites();
                        if ( !$status->isGood() ) {
                                $this->showStatusMessage( $status );
                        }
                        if ( !$status->isOK() ) {
                                unset( $databases[$db] );
                        }
                }
                $databases = array_flip( $databases );
                if ( !$databases ) {
                        $this->showError( 'config-no-db', $wgLang->commaList( $allNames ) );
                        // @todo FIXME: This only works for the web installer!
                        return false;
                }
                $this->setVar( '_CompiledDBs', $databases );
                return true;
        }

        protected function envCheckRegisterGlobals() {
                if( wfIniGetBool( 'register_globals' ) ) {
                        $this->showMessage( 'config-register-globals' );
                }
        }

        protected function envCheckBrokenXML() {
                $test = new PhpXmlBugTester();
                if ( !$test->ok ) {
                        $this->showError( 'config-brokenlibxml' );
                        return false;
                }
                return true;
        }

        protected function envCheckPHP531() {
                $test = new PhpRefCallBugTester;
                $test->execute();
                if ( !$test->ok ) {
                        $this->showError( 'config-using531', phpversion() );
                        return false;
                }
                return true;
        }

        protected function envCheckMagicQuotes() {
                if( wfIniGetBool( "magic_quotes_runtime" ) ) {
                        $this->showError( 'config-magic-quotes-runtime' );
                        return false;
                }
                return true;
        }

        protected function envCheckMagicSybase() {
                if ( wfIniGetBool( 'magic_quotes_sybase' ) ) {
                        $this->showError( 'config-magic-quotes-sybase' );
                        return false;
                }
                return true;
        }

        protected function envCheckMbstring() {
                if ( wfIniGetBool( 'mbstring.func_overload' ) ) {
                        $this->showError( 'config-mbstring' );
                        return false;
                }
                return true;
        }

        protected function envCheckZE1() {
                if ( wfIniGetBool( 'zend.ze1_compatibility_mode' ) ) {
                        $this->showError( 'config-ze1' );
                        return false;
                }
                return true;
        }

        protected function envCheckSafeMode() {
                if ( wfIniGetBool( 'safe_mode' ) ) {
                        $this->setVar( '_SafeMode', true );
                        $this->showMessage( 'config-safe-mode' );
                }
                return true;
        }

        protected function envCheckXML() {
                if ( !function_exists( "utf8_encode" ) ) {
                        $this->showError( 'config-xml-bad' );
                        return false;
                }
                return true;
        }

        protected function envCheckPCRE() {
                if ( !function_exists( 'preg_match' ) ) {
                        $this->showError( 'config-pcre' );
                        return false;
                }
                wfSuppressWarnings();
                $regexd = preg_replace( '/[\x{0430}-\x{04FF}]/iu', '', '-АБВГД-' );
                // Need to check for \p support too, as PCRE can be compiled
                // with utf8 support, but not unicode property support.
                // check that \p{Zs} (space separators) matches
                // U+3000 (Ideographic space)
                $regexprop = preg_replace( '/\p{Zs}/u', '', "-\xE3\x80\x80-" );
                wfRestoreWarnings();
                if ( $regexd != '--' || $regexprop != '--' ) {
                        $this->showError( 'config-pcre-no-utf8' );
                        return false;
                }
                return true;
        }

        protected function envCheckMemory() {
                $limit = ini_get( 'memory_limit' );

                if ( !$limit || $limit == -1 ) {
                        return true;
                }

                $n = wfShorthandToInteger( $limit );

                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 );
                        }
                }
                return true;
        }

        protected function envCheckCache() {
                $caches = array();
                foreach ( $this->objectCaches as $name => $function ) {
                        if ( function_exists( $function ) ) {
                                if ( $name == 'xcache' && !wfIniGetBool( 'xcache.var_size' ) ) {
                                        continue;
                                }
                                $caches[$name] = true;
                        }
                }

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

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

        protected function envCheckModSecurity() {
                if ( self::apacheModulePresent( 'mod_security' ) ) {
                        $this->showMessage( 'config-mod-security' );
                }
                return true;
        }

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

                $diff3 = self::locateExecutableInDefaultPaths( $names, $versionInfo );

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

        protected function envCheckGraphics() {
                $names = array( wfIsWindows() ? 'convert.exe' : 'convert' );
                $convert = self::locateExecutableInDefaultPaths( $names, array( '$1 -version', 'ImageMagick' ) );

                $this->setVar( 'wgImageMagickConvertCommand', '' );
                if ( $convert ) {
                        $this->setVar( 'wgImageMagickConvertCommand', $convert );
                        $this->showMessage( 'config-imagemagick', $convert );
                        return true;
                } elseif ( function_exists( 'imagejpeg' ) ) {
                        $this->showMessage( 'config-gd' );

                } else {
                        $this->showMessage( 'config-no-scaling' );
                }
                return true;
        }

        protected function envCheckServer() {
                $server = $this->envGetDefaultServer();
                $this->showMessage( 'config-using-server', $server );
                $this->setVar( 'wgServer', $server );
                return true;
        }

        protected abstract function envGetDefaultServer();

        protected function envCheckPath() {
                global $IP;
                $IP = dirname( dirname( __DIR__ ) );
                $this->setVar( 'IP', $IP );

                $this->showMessage( 'config-using-uri', $this->getVar( 'wgServer' ), $this->getVar( 'wgScriptPath' ) );
                return true;
        }

        protected function envCheckExtension() {
                // @todo FIXME: Detect this properly
                if ( defined( 'MW_INSTALL_PHP5_EXT' ) ) {
                        $ext = 'php5';
                } else {
                        $ext = 'php';
                }
                $this->setVar( 'wgScriptExtension', ".$ext" );
                return true;
        }

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

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

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

                if ( $ret ) {
                        return true;
                }

                $lines = wfArrayMap( 'trim', explode( "\n", $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' ) );
                        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 );
                                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] );
                        return true;
                }

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

                # Give up.
                return true;
        }

        protected function envCheckUploadsDirectory() {
                global $IP;

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

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

        protected function envCheckSuhosinMaxValueLength() {
                $maxValueLength = ini_get( 'suhosin.get.max_value_length' );
                if ( $maxValueLength > 0 ) {
                        if( $maxValueLength < 1024 ) {
                                # Only warn if the value is below the sane 1024
                                $this->showMessage( 'config-suhosin-max-value-length', $maxValueLength );
                        }
                } else {
                        $maxValueLength = -1;
                }
                $this->setVar( 'wgResourceLoaderMaxQueryLength', $maxValueLength );
                return true;
        }

        protected function unicodeChar( $c ) {
                $c = hexdec($c);
                if ($c <= 0x7F) {
                        return chr($c);
                } elseif ($c <= 0x7FF) {
                        return chr(0xC0 | $c >> 6) . chr(0x80 | $c & 0x3F);
                } elseif ($c <= 0xFFFF) {
                        return chr(0xE0 | $c >> 12) . chr(0x80 | $c >> 6 & 0x3F)
                                . chr(0x80 | $c & 0x3F);
                } elseif ($c <= 0x10FFFF) {
                        return chr(0xF0 | $c >> 18) . chr(0x80 | $c >> 12 & 0x3F)
                                . chr(0x80 | $c >> 6 & 0x3F)
                                . chr(0x80 | $c & 0x3F);
                } else {
                        return false;
                }
        }


        protected function envCheckLibicu() {
                $utf8 = function_exists( 'utf8_normalize' );
                $intl = function_exists( 'normalizer_normalize' );

                $not_normal_c = $this->unicodeChar("FA6C");
                $normal_c = $this->unicodeChar("242EE");

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

                if( $utf8 ) {
                        $useNormalizer = 'utf8';
                        $utf8 = utf8_normalize( $not_normal_c, UtfNormal::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'
                if( $useNormalizer === 'php' ) {
                        $this->showMessage( 'config-unicode-pure-php-warning' );
                } else {
                        $this->showMessage( 'config-unicode-using-' . $useNormalizer );
                        if( $needsUpdate ) {
                                $this->showMessage( 'config-unicode-update-warning' );
                        }
                }
        }

        protected function envCheckCtype() {
                if ( !function_exists( 'ctype_digit' ) ) {
                        $this->showError( 'config-ctype' );
                        return false;
                }
                return true;
        }

        protected static 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' ) )
                );
        }

        public static function locateExecutable( $path, $names, $versionInfo = false ) {
                if ( !is_array( $names ) ) {
                        $names = array( $names );
                }

                foreach ( $names as $name ) {
                        $command = $path . DIRECTORY_SEPARATOR . $name;

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

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

                                $file = str_replace( '$1', wfEscapeShellArg( $command ), $versionInfo[0] );
                                if ( strstr( wfShellExec( $file ), $versionInfo[1] ) !== false ) {
                                        return $command;
                                }
                        }
                }
                return false;
        }

        public static function locateExecutableInDefaultPaths( $names, $versionInfo = false ) {
                foreach( self::getPossibleBinPaths() as $path ) {
                        $exe = self::locateExecutable( $path, $names, $versionInfo );
                        if( $exe !== false ) {
                                return $exe;
                        }
                }
                return false;
        }

        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;
                                }

                                try {
                                        $text = Http::get( $url . $file, array( 'timeout' => 3 ) );
                                }
                                catch( MWException $e ) {
                                        // Http::get throws with allow_url_fopen = false and no curl extension.
                                        $text = null;
                                }
                                unlink( $dir . $file );

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

                wfRestoreWarnings();

                return false;
        }

        public static function apacheModulePresent( $moduleName ) {
                if ( function_exists( 'apache_get_modules' ) && in_array( $moduleName, apache_get_modules() ) ) {
                        return true;
                }
                // try it the hard way
                ob_start();
                phpinfo( INFO_MODULES );
                $info = ob_get_clean();
                return strpos( $info, $moduleName ) !== false;
        }

        public function setParserLanguage( $lang ) {
                $this->parserOptions->setTargetLanguage( $lang );
                $this->parserOptions->setUserLang( $lang );
        }

        protected function getDocUrl( $page ) {
                return "{$_SERVER['PHP_SELF']}?page=" . urlencode( $page );
        }

        public function findExtensions() {
                if( $this->getVar( 'IP' ) === null ) {
                        return false;
                }

                $exts = array();
                $extDir = $this->getVar( 'IP' ) . '/extensions';
                $dh = opendir( $extDir );

                while ( ( $file = readdir( $dh ) ) !== false ) {
                        if( !is_dir( "$extDir/$file" ) ) {
                                continue;
                        }
                        if( file_exists( "$extDir/$file/$file.php" ) ) {
                                $exts[] = $file;
                        }
                }
                natcasesort( $exts );

                return $exts;
        }

        protected function includeExtensions() {
                global $IP;
                $exts = $this->getVar( '_Extensions' );
                $IP = $this->getVar( 'IP' );

                global $wgAutoloadClasses;
                $wgAutoloadClasses = array();

                require( "$IP/includes/DefaultSettings.php" );

                foreach( $exts as $e ) {
                        require_once( "$IP/extensions/$e/$e.php" );
                }

                $hooksWeWant = isset( $wgHooks['LoadExtensionSchemaUpdates'] ) ?
                        $wgHooks['LoadExtensionSchemaUpdates'] : array();

                // Unset everyone else's hooks. Lord knows what someone might be doing
                // in ParserFirstCallInit (see bug 27171)
                $GLOBALS['wgHooks'] = array( 'LoadExtensionSchemaUpdates' => $hooksWeWant );

                return Status::newGood();
        }

        protected function getInstallSteps( DatabaseInstaller $installer ) {
                $coreInstallSteps = array(
                        array( 'name' => 'database',   'callback' => array( $installer, 'setupDatabase' ) ),
                        array( 'name' => 'tables',     'callback' => array( $installer, 'createTables' ) ),
                        array( 'name' => 'interwiki',  'callback' => array( $installer, 'populateInterwikiTable' ) ),
                        array( 'name' => 'stats',      'callback' => array( $this, 'populateSiteStats' ) ),
                        array( 'name' => 'keys',       'callback' => array( $this, 'generateKeys' ) ),
                        array( 'name' => 'sysop',      'callback' => array( $this, 'createSysop' ) ),
                        array( 'name' => 'mainpage',   'callback' => array( $this, 'createMainpage' ) ),
                );

                // Build the array of install steps starting from the core install list,
                // then adding any callbacks that wanted to attach after a given step
                foreach( $coreInstallSteps as $step ) {
                        $this->installSteps[] = $step;
                        if( isset( $this->extraInstallSteps[ $step['name'] ] ) ) {
                                $this->installSteps = array_merge(
                                        $this->installSteps,
                                        $this->extraInstallSteps[ $step['name'] ]
                                );
                        }
                }

                // Prepend any steps that want to be at the beginning
                if( isset( $this->extraInstallSteps['BEGINNING'] ) ) {
                        $this->installSteps = array_merge(
                                $this->extraInstallSteps['BEGINNING'],
                                $this->installSteps
                        );
                }

                // Extensions should always go first, chance to tie into hooks and such
                if( count( $this->getVar( '_Extensions' ) ) ) {
                        array_unshift( $this->installSteps,
                                array( 'name' => 'extensions', 'callback' => array( $this, 'includeExtensions' ) )
                        );
                        $this->installSteps[] = array(
                                'name' => 'extension-tables',
                                'callback' => array( $installer, 'createExtensionTables' )
                        );
                }
                return $this->installSteps;
        }

        public function performInstallation( $startCB, $endCB ) {
                $installResults = array();
                $installer = $this->getDBInstaller();
                $installer->preInstall();
                $steps = $this->getInstallSteps( $installer );
                foreach( $steps as $stepObj ) {
                        $name = $stepObj['name'];
                        call_user_func_array( $startCB, array( $name ) );

                        // Perform the callback step
                        $status = call_user_func( $stepObj['callback'], $installer );

                        // Output and save the results
                        call_user_func( $endCB, $name, $status );
                        $installResults[$name] = $status;

                        // If we've hit some sort of fatal, we need to bail.
                        // Callback already had a chance to do output above.
                        if( !$status->isOk() ) {
                                break;
                        }
                }
                if( $status->isOk() ) {
                        $this->setVar( '_InstallDone', true );
                }
                return $installResults;
        }

        public function generateKeys() {
                $keys = array( 'wgSecretKey' => 64 );
                if ( strval( $this->getVar( 'wgUpgradeKey' ) ) === '' ) {
                        $keys['wgUpgradeKey'] = 16;
                }
                return $this->doGenerateKeys( $keys );
        }

        protected function doGenerateKeys( $keys ) {
                $status = Status::newGood();

                $strong = true;
                foreach ( $keys as $name => $length ) {
                        $secretKey = MWCryptRand::generateHex( $length, true );
                        if ( !MWCryptRand::wasStrong() ) {
                                $strong = false;
                        }

                        $this->setVar( $name, $secretKey );
                }

                if ( !$strong ) {
                        $names = array_keys( $keys );
                        $names = preg_replace( '/^(.*)$/', '\$$1', $names );
                        global $wgLang;
                        $status->warning( 'config-insecure-keys', $wgLang->listToText( $names ), count( $names ) );
                }

                return $status;
        }

        protected function createSysop() {
                $name = $this->getVar( '_AdminName' );
                $user = User::newFromName( $name );

                if ( !$user ) {
                        // We should've validated this earlier anyway!
                        return Status::newFatal( 'config-admin-error-user', $name );
                }

                if ( $user->idForName() == 0 ) {
                        $user->addToDatabase();

                        try {
                                $user->setPassword( $this->getVar( '_AdminPassword' ) );
                        } catch( PasswordError $pwe ) {
                                return Status::newFatal( 'config-admin-error-password', $name, $pwe->getMessage() );
                        }

                        $user->addGroup( 'sysop' );
                        $user->addGroup( 'bureaucrat' );
                        if( $this->getVar( '_AdminEmail' ) ) {
                                $user->setEmail( $this->getVar( '_AdminEmail' ) );
                        }
                        $user->saveSettings();

                        // Update user count
                        $ssUpdate = new SiteStatsUpdate( 0, 0, 0, 0, 1 );
                        $ssUpdate->doUpdate();
                }
                $status = Status::newGood();

                if( $this->getVar( '_Subscribe' ) && $this->getVar( '_AdminEmail' ) ) {
                        $this->subscribeToMediaWikiAnnounce( $status );
                }

                return $status;
        }

        private function subscribeToMediaWikiAnnounce( Status $s ) {
                $params = array(
                        'email'    => $this->getVar( '_AdminEmail' ),
                        'language' => 'en',
                        'digest'   => 0
                );

                // Mailman doesn't support as many languages as we do, so check to make
                // sure their selected language is available
                $myLang = $this->getVar( '_UserLang' );
                if( in_array( $myLang, $this->mediaWikiAnnounceLanguages ) ) {
                        $myLang = $myLang == 'pt-br' ? 'pt_BR' : $myLang; // rewrite to Mailman's pt_BR
                        $params['language'] = $myLang;
                }

                if( MWHttpRequest::canMakeRequests() ) {
                        $res = MWHttpRequest::factory( $this->mediaWikiAnnounceUrl,
                                array( 'method' => 'POST', 'postData' => $params ) )->execute();
                        if( !$res->isOK() ) {
                                $s->warning( 'config-install-subscribe-fail', $res->getMessage() );
                        }
                } else {
                        $s->warning( 'config-install-subscribe-notpossible' );
                }
        }

        protected function createMainpage( DatabaseInstaller $installer ) {
                $status = Status::newGood();
                try {
                        $page = WikiPage::factory( Title::newMainPage() );
                        $page->doEdit( wfMessage( 'mainpagetext' )->inContentLanguage()->text() . "\n\n" .
                                        wfMessage( 'mainpagedocfooter' )->inContentLanguage()->text(),
                                        '',
                                        EDIT_NEW,
                                        false,
                                        User::newFromName( 'MediaWiki default' )
                        );
                } catch (MWException $e) {
                        //using raw, because $wgShowExceptionDetails can not be set yet
                        $status->fatal( 'config-install-mainpage-failed', $e->getMessage() );
                }

                return $status;
        }

        public static function overrideConfig() {
                define( 'MW_NO_SESSION', 1 );

                // Don't access the database
                $GLOBALS['wgUseDatabaseMessages'] = false;
                // Don't cache langconv tables
                $GLOBALS['wgLanguageConverterCacheType'] = CACHE_NONE;
                // Debug-friendly
                $GLOBALS['wgShowExceptionDetails'] = true;
                // Don't break forms
                $GLOBALS['wgExternalLinkTarget'] = '_blank';

                // Extended debugging
                $GLOBALS['wgShowSQLErrors'] = true;
                $GLOBALS['wgShowDBErrorBacktrace'] = true;

                // Allow multiple ob_flush() calls
                $GLOBALS['wgDisableOutputCompression'] = true;

                // Use a sensible cookie prefix (not my_wiki)
                $GLOBALS['wgCookiePrefix'] = 'mw_installer';

                // Some of the environment checks make shell requests, remove limits
                $GLOBALS['wgMaxShellMemory'] = 0;
        }

        public function addInstallStep( $callback, $findStep = 'BEGINNING' ) {
                $this->extraInstallSteps[$findStep][] = $callback;
        }

        protected function disableTimeLimit() {
                wfSuppressWarnings();
                set_time_limit( 0 );
                wfRestoreWarnings();
        }
}