Follow-up r67045. Delete it from the English message file too.

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

<?php

/**
 * Base installer class
 * Handles everything that is independent of user interface
 */
abstract class Installer {
        var $settings, $output;

        /**
         * MediaWiki configuration globals that will eventually be passed through 
         * to LocalSettings.php. The names only are given here, the defaults 
         * typically come from DefaultSettings.php.
         * @protected
         */
        var $defaultVarNames = array(
                'wgSitename',
                'wgPasswordSender',
                'wgLanguageCode', 
                'wgRightsIcon',
                'wgRightsText',
                'wgRightsUrl',
                'wgMainCacheType',
                'wgEnableEmail',
                'wgEnableUserEmail',
                'wgEnotifUserTalk',
                'wgEnotifWatchlist',
                'wgEmailAuthentication',
                'wgDBtype',
                'wgDiff3',
                'wgImageMagickConvertCommand',
                'IP',
                'wgScriptPath',
                'wgScriptExtension',
                'wgMetaNamespace',
//              'wgDeletedDirectory',
                'wgEnableUploads',
                'wgLogo',
                'wgShellLocale',
                'wgSecretKey',
        );

        /**
         * Variables that are stored alongside globals, and are used for any 
         * configuration of the installation process aside from the MediaWiki 
         * configuration. Map of names to defaults.
         * @protected
         */
        var $internalDefaults = array(
                '_UserLang' => 'en',
                '_Environment' => false,
                '_CompiledDBs' => array(),
                '_SafeMode' => false,
                '_RaiseMemory' => false,
                '_UpgradeDone' => false,
                '_Caches' => array(),
                '_InstallUser' => 'root',
                '_InstallPassword' => '',
                '_SameAccount' => true,
                '_CreateDBAccount' => false,
                '_NamespaceType' => 'site-name',
                '_AdminName' => null, // 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' => '',
        );

        /**
         * 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.
         * @private
         */
        var $dbTypes = array(
                'mysql',
                'postgres',
                'sqlite',
                'oracle'
        );

        /**
         * Minimum memory size in MB
         */
        private $minMemorySize = 50;

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

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

        var $installSteps = array(
                'database',
                'tables',
                'interwiki',
                'secretkey',
                'sysop',
                'localsettings',
        );

        /**
         * Known object cache types and the functions used to test for their existence
         * @protected
         */
        var $objectCaches = array( 
                'xcache' => 'xcache_get',
                'apc' => 'apc_fetch',
                'eaccel' => 'eaccelerator_get',
                'wincache' => 'wincache_ucache_get'
        );

        /**
         * User rights profiles
         */
        var $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,
                        ),
                ),
        );

        /**
         * License types
         */
        var $licenses = array(
                'none' => array(
                        'url' => '',
                        'icon' => '',
                        'text' => ''
                ),
                'cc-by-sa' => array(
                        'url' => 'http://creativecommons.org/licenses/by-sa/3.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-by-sa.png',
                ),
                'cc-by-nc-sa' => array(
                        'url' => 'http://creativecommons.org/licenses/by-nc-sa/3.0/',
                        'icon' => '{$wgStylePath}/common/images/cc-by-nc-sa.png',
                ),
                'pd' => array(
                        'url' => 'http://creativecommons.org/licenses/publicdomain/',
                        'icon' => '{$wgStylePath}/common/images/public-domain.png',
                ),
                'gfdl-old' => array(
                        'url' => 'http://www.gnu.org/licenses/old-licenses/fdl-1.2.html',
                        'icon' => '{$wgStylePath}/common/images/gnu-fdl.png',
                ),
                'gfdl-current' => array(
                        'url' => 'http://www.gnu.org/copyleft/fdl.html',
                        'icon' => '{$wgStylePath}/common/images/gnu-fdl.png',
                ),
                'cc-choose' => array(
                        // details will be filled in by the selector
                        'url' => '', 
                        'icon' => '',
                        'text' => '',
                ),
        );
        /**
         * Cached Title and ParserOptions used by parse()
         * @private
         */
        var $parserTitle, $parserOptions;

        /**
         * Constructor, always call this from child classes
         */
        function __construct() {
                $this->settings = $this->internalDefaults;
                foreach ( $this->defaultVarNames as $var ) {
                        $this->settings[$var] = $GLOBALS[$var];
                }
                foreach ( $this->dbTypes as $type ) {
                        $installer = $this->getDBInstaller( $type );
                        if ( !$installer->isCompiled() ) {
                                continue;
                        }
                        $defaults = $installer->getGlobalDefaults();
                        foreach ( $installer->getGlobalNames() as $var ) {
                                if ( isset( $defaults[$var] ) ) {
                                        $this->settings[$var] = $defaults[$var];
                                } else {
                                        $this->settings[$var] = $GLOBALS[$var];
                                }
                        }
                }

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

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

        abstract function showStatusError( $status );

        /**
         * Get a list of known DB types
         */
        function getDBTypes() {
                return $this->dbTypes;
        }

        /**
         * Get an instance of InstallerDBType for the specified DB type
         * @param $type Mixed: DB installer for which is needed, false to use default
         */
        function getDBInstaller( $type = false ) {
                if ( !$type ) {
                        $type = $this->getVar( 'wgDBtype' );
                }
                if ( !isset( $this->dbInstallers[$type] ) ) {
                        $class = ucfirst( $type ). 'Installer';
                        $this->dbInstallers[$type] = new $class( $this );
                }
                return $this->dbInstallers[$type];
        }

        /**
         * 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.
         */
        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;
        }

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

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

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

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

        /**
         * Returns true if dl() can be used
         */
        function haveDl() {
                return function_exists( 'dl' )
                        && is_callable( 'dl' )
                        && wfIniGetBool( 'enable_dl' )
                        && !wfIniGetBool( 'safe_mode' );
        }
        
        /** Check if we're installing the latest version */
        function envLatestVersion() {
                global $wgVersion;
                $latestInfoUrl = 'http://www.mediawiki.org/w/api.php?action=mwreleases&format=json';
                $latestInfo = Http::get( $latestInfoUrl );
                if( !$latestInfo ) {
                        $this->showMessage( 'config-env-latest-can-not-check', $latestInfoUrl );
                        return;
                }
                $latestInfo = FormatJson::decode($latestInfo);
                if ($latestInfo === false || !isset( $latestInfo->mwreleases ) ) {
                        # 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-data-invalid', $latestInfoUrl );
                        return;
                }
                foreach( $latestInfo->mwreleases as $rel ) {
                        if( isset( $rel->current ) )
                                $currentVersion = $rel->version;
                }
                if( version_compare( $wgVersion, $currentVersion, '<' ) ) {
                        $this->showMessage( 'config-env-latest-old' );
                        $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 */
        function envCheckDB() {
                $compiledDBs = array();
                $haveDl = $this->haveDl();
                $goodNames = array();
                $allNames = array();
                foreach ( $this->dbTypes as $name ) {
                        $db = $this->getDBInstaller( $name );
                        $readableName = wfMsg( 'config-type-' . $name );
                        if ( $db->isCompiled() ) {
                                $compiledDBs[] = $name;
                                $goodNames[] = $readableName;
                        }
                        $allNames[] = $readableName;
                }
                $this->setVar( '_CompiledDBs', $compiledDBs );

                global $wgLang;
                if ( !$compiledDBs ) {
                        $this->showMessage( 'config-no-db' );
                        $this->showHelpBox( 'config-no-db-help', $wgLang->commaList( $allNames ) );
                        return false;
                }
                $this->showMessage( 'config-have-db', $wgLang->commaList( $goodNames ) );
        }

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

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

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

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

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

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

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

        /** Environment check for available memory */
        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( false === ini_set( "memory_limit", $newLimit ) ) {
                                $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 */
        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 */
        function envCheckDiff3() {
                $paths = array_merge(
                        array(
                                "/usr/bin",
                                "/usr/local/bin",
                                "/opt/csw/bin",
                                "/usr/gnu/bin",
                                "/usr/sfw/bin" ),
                        explode( PATH_SEPARATOR, getenv( "PATH" ) ) );
                $names = array( "gdiff3", "diff3", "diff3.exe" );

                $versionInfo = array( '$1 --version 2>&1', 'diff3 (GNU diffutils)' );
                $haveDiff3 = false;
                foreach ( $paths 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' );
                }
        }

        /**
         * 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
         *
         * @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.
         */
        function locateExecutable( $path, $names, $versionInfo = false ) {
                if (!is_array($names))
                        $names = array($names);

                foreach ($names as $name) {
                        $command = "$path/$name";
                        if ( @file_exists( $command ) ) {
                                if ( !$versionInfo )
                                        return $command;

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

        /** Environment check for ImageMagick and GD */
        function envCheckGraphics() {
                $imcheck = array( "/usr/bin", "/opt/csw/bin", "/usr/local/bin", "/sw/bin", "/opt/local/bin" );
                foreach( $imcheck as $dir ) {
                        $im = "$dir/convert";
                        if( @file_exists( $im ) ) {
                                $this->showMessage( 'config-imagemagick', $im );
                                $this->setVar( 'wgImageMagickConvertCommand', $im );
                                return true;
                        }
                }
                if ( function_exists( 'imagejpeg' ) ) {
                        $this->showMessage( 'config-gd' );
                        return true;
                }
                $this->showMessage( 'no-scaling' );
        }

        /** Environment check for setting $IP and $wgScriptPath */
        function envCheckPath() {
                $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 */
        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 */
        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 );
        }

        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;
        }
        
        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 );
                }
        }

        /**
         * Checks if scripts located in the given directory can be executed via the given URL
         */
        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;
        }

        /**
         * 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
         */
        function parse( $text, $lineStart = false ) {
                global $wgParser;
                try {
                        $out = $wgParser->parse( $text, $this->parserTitle, $this->parserOptions, $lineStart );
                        $html = $out->getText();
                } catch ( InstallerDBAccessError $e ) {
                        $html = '<!--DB access attempted during parse-->  ' . htmlspecialchars( $text );
                        if ( !empty( $this->debug ) ) {
                                $html .= "<!--\n" . $e->getTraceAsString() . "\n-->";
                        }
                }
                return $html;
        }

        /**
         * Extension tag hook for a documentation link
         */
        function docLink( $linkText, $attribs, $parser ) {
                $url = $this->getDocUrl( $attribs['href'] );
                return '<a href="' . htmlspecialchars( $url ) . '">' . 
                        htmlspecialchars( $linkText ) . 
                        '</a>';
        }

        /**
         * Overridden by WebInstaller to provide lastPage parameters
         */
        protected function getDocUrl( $page ) {
                return "{$_SERVER['PHP_SELF']}?page=" . urlencode( $attribs['href'] );
        }

        public function findExtensions() {
                if( $this->getVar( 'IP' ) === null ) {
                        return false;
                }
                $exts = array();
                $dir = $this->getVar( 'IP' ) . '/extensions';
                $dh = opendir( $dir );
                while ( ( $file = readdir( $dh ) ) !== false ) {
                        if( file_exists( "$dir/$file/$file.php" ) ) {
                                $exts[] = $file;
                        }
                }
                $this->setVar( '_Extensions', $exts );
                return $exts;
        }

        public function getInstallSteps() {
                if( $this->getVar( '_UpgradeDone' ) ) {
                        $this->installSteps = array( 'localsettings' );
                }
                if( count( $this->getVar( '_Extensions' ) ) ) {
                        array_unshift( $this->installSteps, 'extensions' );
                }
                return $this->installSteps;
        }

        public function installExtensions() {
                global $wgHooks, $wgAutoloadClasses;
                $exts = $this->getVar( '_Extensions' );
                $path = $this->getVar( 'IP' ) . '/extensions';
                foreach( $exts as $e ) {
                        require( "$path/$e/$e.php" );
                }
                return Status::newGood();
        }

        public function installDatabase() {
                $installer = $this->getDBInstaller( $this->getVar( 'wgDBtype' ) );
                $status = $installer->setupDatabase();
                return $status;
        }

        public function installTables() {
                $installer = $this->getDBInstaller();
                $status = $installer->createTables();
                if( $status->isGood() ) {
                        LBFactory::enableBackend();
                }
                return $status;
        }

        public function installInterwiki() {
                $installer = $this->getDBInstaller();
                return $installer->populateInterwikiTable();
        }

        public function installSecretKey() {
                $file = wfIsWindows() ? null : @fopen( "/dev/urandom", "r" );
                if ( $file ) {
                        $secretKey = bin2hex( fread( $file, 32 ) );
                        fclose( $file );
                } else {
                        $secretKey = "";
                        for ( $i=0; $i<8; $i++ ) {
                                $secretKey .= dechex(mt_rand(0, 0x7fffffff));
                        }
                        $this->output->addWarningMsg( 'config-insecure-secretkey' );
                }
                $this->setVar( 'wgSecretKey', $secretKey );
                return Status::newGood();
        }

        public function installSysop() {
                $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->saveSettings();
                        $user->addGroup( 'sysop' );
                        $user->addGroup( 'bureaucrat' );
                }
                return Status::newGood();
        }

        public function installLocalsettings() {
                $localSettings = new LocalSettingsGenerator( $this );
                $ok = $localSettings->writeLocalSettings();

                # TODO: Make writeLocalSettings() itself not warn, but instead return
                # a Status object to us to pass along.
                if ( $ok ) {
                        return Status::newGood();
                } else {
                        return Status::newFatal();
                }
        }

        /*
         * 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 String
         */
        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;
        }
}