ExtensionRegistry.php

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<?php

class ExtensionRegistry {

    const MEDIAWIKI_CORE = 'MediaWiki';

    const MANIFEST_VERSION = 1;

    const OLDEST_MANIFEST_VERSION = 1;

    const CACHE_VERSION = 3;

    const MERGE_STRATEGY = '_merge_strategy';

    protected $cache;

    private $loaded = [];

    protected $queued = [];

    protected $attributes = [];

    private static $instance;

    public static function getInstance() {
        if ( self::$instance === null ) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    public function __construct() {
        // We use a try/catch instead of the $fallback parameter because
        // we don't want to fail here if $wgObjectCaches is not configured
        // properly for APC setup
        try {
            $this->cache = ObjectCache::getLocalServerInstance();
        } catch ( MWException $e ) {
            $this->cache = new EmptyBagOStuff();
        }
    }

    public function queue( $path ) {
        global $wgExtensionInfoMTime;

        $mtime = $wgExtensionInfoMTime;
        if ( $mtime === false ) {
            if ( file_exists( $path ) ) {
                $mtime = filemtime( $path );
            } else {
                throw new Exception( "$path does not exist!" );
            }
            if ( !$mtime ) {
                $err = error_get_last();
                throw new Exception( "Couldn't stat $path: {$err['message']}" );
            }
        }
        $this->queued[$path] = $mtime;
    }

    public function loadFromQueue() {
        global $wgVersion;
        if ( !$this->queued ) {
            return;
        }

        // A few more things to vary the cache on
        $versions = [
            'registration' => self::CACHE_VERSION,
            'mediawiki' => $wgVersion
        ];

        // See if this queue is in APC
        $key = wfMemcKey(
            'registration',
            md5( json_encode( $this->queued + $versions ) )
        );
        $data = $this->cache->get( $key );
        if ( $data ) {
            $this->exportExtractedData( $data );
        } else {
            $data = $this->readFromQueue( $this->queued );
            $this->exportExtractedData( $data );
            // Do this late since we don't want to extract it since we already
            // did that, but it should be cached
            $data['globals']['wgAutoloadClasses'] += $data['autoload'];
            unset( $data['autoload'] );
            $this->cache->set( $key, $data, 60 * 60 * 24 );
        }
        $this->queued = [];
    }

    public function getQueue() {
        return $this->queued;
    }

    public function clearQueue() {
        $this->queued = [];
    }

    public function readFromQueue( array $queue ) {
        global $wgVersion;
        $autoloadClasses = [];
        $autoloaderPaths = [];
        $processor = new ExtensionProcessor();
        $incompatible = [];
        $coreVersionParser = new CoreVersionChecker( $wgVersion );
        foreach ( $queue as $path => $mtime ) {
            $json = file_get_contents( $path );
            if ( $json === false ) {
                throw new Exception( "Unable to read $path, does it exist?" );
            }
            $info = json_decode( $json, /* $assoc = */ true );
            if ( !is_array( $info ) ) {
                throw new Exception( "$path is not a valid JSON file." );
            }
            if ( !isset( $info['manifest_version'] ) ) {
                // For backwards-compatability, assume a version of 1
                $info['manifest_version'] = 1;
            }
            $version = $info['manifest_version'];
            if ( $version < self::OLDEST_MANIFEST_VERSION || $version > self::MANIFEST_VERSION ) {
                throw new Exception( "$path: unsupported manifest_version: {$version}" );
            }
            $autoload = $this->processAutoLoader( dirname( $path ), $info );
            // Set up the autoloader now so custom processors will work
            $GLOBALS['wgAutoloadClasses'] += $autoload;
            $autoloadClasses += $autoload;
            // Check any constraints against MediaWiki core
            $requires = $processor->getRequirements( $info );
            if ( isset( $requires[self::MEDIAWIKI_CORE] )
                && !$coreVersionParser->check( $requires[self::MEDIAWIKI_CORE] )
            ) {
                // Doesn't match, mark it as incompatible.
                $incompatible[] = "{$info['name']} is not compatible with the current "
                    . "MediaWiki core (version {$wgVersion}), it requires: " . $requires[self::MEDIAWIKI_CORE]
                    . '.';
                continue;
            }
            // Get extra paths for later inclusion
            $autoloaderPaths = array_merge( $autoloaderPaths,
                $processor->getExtraAutoloaderPaths( dirname( $path ), $info ) );
            // Compatible, read and extract info
            $processor->extractInfo( $path, $info, $version );
        }
        if ( $incompatible ) {
            if ( count( $incompatible ) === 1 ) {
                throw new Exception( $incompatible[0] );
            } else {
                throw new Exception( implode( "\n", $incompatible ) );
            }
        }
        $data = $processor->getExtractedInfo();
        // Need to set this so we can += to it later
        $data['globals']['wgAutoloadClasses'] = [];
        $data['autoload'] = $autoloadClasses;
        $data['autoloaderPaths'] = $autoloaderPaths;
        return $data;
    }

    protected function exportExtractedData( array $info ) {
        foreach ( $info['globals'] as $key => $val ) {
            // If a merge strategy is set, read it and remove it from the value
            // so it doesn't accidentally end up getting set.
            if ( is_array( $val ) && isset( $val[self::MERGE_STRATEGY] ) ) {
                $mergeStrategy = $val[self::MERGE_STRATEGY];
                unset( $val[self::MERGE_STRATEGY] );
            } else {
                $mergeStrategy = 'array_merge';
            }

            // Optimistic: If the global is not set, or is an empty array, replace it entirely.
            // Will be O(1) performance.
            if ( !isset( $GLOBALS[$key] ) || ( is_array( $GLOBALS[$key] ) && !$GLOBALS[$key] ) ) {
                $GLOBALS[$key] = $val;
                continue;
            }

            if ( !is_array( $GLOBALS[$key] ) || !is_array( $val ) ) {
                // config setting that has already been overridden, don't set it
                continue;
            }

            switch ( $mergeStrategy ) {
                case 'array_merge_recursive':
                    $GLOBALS[$key] = array_merge_recursive( $GLOBALS[$key], $val );
                    break;
                case 'array_plus_2d':
                    $GLOBALS[$key] = wfArrayPlus2d( $GLOBALS[$key], $val );
                    break;
                case 'array_plus':
                    $GLOBALS[$key] += $val;
                    break;
                case 'array_merge':
                    $GLOBALS[$key] = array_merge( $val, $GLOBALS[$key] );
                    break;
                default:
                    throw new UnexpectedValueException( "Unknown merge strategy '$mergeStrategy'" );
            }
        }

        foreach ( $info['defines'] as $name => $val ) {
            define( $name, $val );
        }
        foreach ( $info['autoloaderPaths'] as $path ) {
            require_once $path;
        }
        foreach ( $info['callbacks'] as $cb ) {
            call_user_func( $cb );
        }

        $this->loaded += $info['credits'];
        if ( $info['attributes'] ) {
            if ( !$this->attributes ) {
                $this->attributes = $info['attributes'];
            } else {
                $this->attributes = array_merge_recursive( $this->attributes, $info['attributes'] );
            }
        }
    }

    public function load( $path ) {
        $this->loadFromQueue(); // First clear the queue
        $this->queue( $path );
        $this->loadFromQueue();
    }

    public function isLoaded( $name ) {
        return isset( $this->loaded[$name] );
    }

    public function getAttribute( $name ) {
        if ( isset( $this->attributes[$name] ) ) {
            return $this->attributes[$name];
        } else {
            return [];
        }
    }

    public function getAllThings() {
        return $this->loaded;
    }

    protected function markLoaded( $name, array $credits ) {
        $this->loaded[$name] = $credits;
    }

    protected function processAutoLoader( $dir, array $info ) {
        if ( isset( $info['AutoloadClasses'] ) ) {
            // Make paths absolute, relative to the JSON file
            return array_map( function( $file ) use ( $dir ) {
                return "$dir/$file";
            }, $info['AutoloadClasses'] );
        } else {
            return [];
        }
    }
}