Merge "Special:Upload should not crash on failing previews"

[mediawiki.git] / includes / import / WikiImporter.php

<?php
/**
 * MediaWiki page data importer.
 *
 * Copyright © 2003,2005 Brion Vibber <brion@pobox.com>
 * https://www.mediawiki.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup SpecialPage
 */
use MediaWiki\MediaWikiServices;

/**
 * XML file reader for the page data importer.
 *
 * implements Special:Import
 * @ingroup SpecialPage
 */
class WikiImporter {
        private $reader = null;
        private $foreignNamespaces = null;
        private $mLogItemCallback, $mUploadCallback, $mRevisionCallback, $mPageCallback;
        private $mSiteInfoCallback, $mPageOutCallback;
        private $mNoticeCallback, $mDebug;
        private $mImportUploads, $mImageBasePath;
        private $mNoUpdates = false;
        /** @var Config */
        private $config;
        /** @var ImportTitleFactory */
        private $importTitleFactory;
        /** @var array */
        private $countableCache = [];
        /** @var bool */
        private $disableStatisticsUpdate = false;

        /**
         * Creates an ImportXMLReader drawing from the source provided
         * @param ImportSource $source
         * @param Config $config
         * @throws Exception
         */
        function __construct( ImportSource $source, Config $config = null ) {
                if ( !class_exists( 'XMLReader' ) ) {
                        throw new Exception( 'Import requires PHP to have been compiled with libxml support' );
                }

                $this->reader = new XMLReader();
                if ( !$config ) {
                        wfDeprecated( __METHOD__ . ' without a Config instance', '1.25' );
                        $config = MediaWikiServices::getInstance()->getMainConfig();
                }
                $this->config = $config;

                if ( !in_array( 'uploadsource', stream_get_wrappers() ) ) {
                        stream_wrapper_register( 'uploadsource', 'UploadSourceAdapter' );
                }
                $id = UploadSourceAdapter::registerSource( $source );

                // Enable the entity loader, as it is needed for loading external URLs via
                // XMLReader::open (T86036)
                $oldDisable = libxml_disable_entity_loader( false );
                if ( defined( 'LIBXML_PARSEHUGE' ) ) {
                        $status = $this->reader->open( "uploadsource://$id", null, LIBXML_PARSEHUGE );
                } else {
                        $status = $this->reader->open( "uploadsource://$id" );
                }
                if ( !$status ) {
                        $error = libxml_get_last_error();
                        libxml_disable_entity_loader( $oldDisable );
                        throw new MWException( 'Encountered an internal error while initializing WikiImporter object: ' .
                                $error->message );
                }
                libxml_disable_entity_loader( $oldDisable );

                // Default callbacks
                $this->setPageCallback( [ $this, 'beforeImportPage' ] );
                $this->setRevisionCallback( [ $this, "importRevision" ] );
                $this->setUploadCallback( [ $this, 'importUpload' ] );
                $this->setLogItemCallback( [ $this, 'importLogItem' ] );
                $this->setPageOutCallback( [ $this, 'finishImportPage' ] );

                $this->importTitleFactory = new NaiveImportTitleFactory();
        }

        /**
         * @return null|XMLReader
         */
        public function getReader() {
                return $this->reader;
        }

        public function throwXmlError( $err ) {
                $this->debug( "FAILURE: $err" );
                wfDebug( "WikiImporter XML error: $err\n" );
        }

        public function debug( $data ) {
                if ( $this->mDebug ) {
                        wfDebug( "IMPORT: $data\n" );
                }
        }

        public function warn( $data ) {
                wfDebug( "IMPORT: $data\n" );
        }

        public function notice( $msg /*, $param, ...*/ ) {
                $params = func_get_args();
                array_shift( $params );

                if ( is_callable( $this->mNoticeCallback ) ) {
                        call_user_func( $this->mNoticeCallback, $msg, $params );
                } else { # No ImportReporter -> CLI
                        echo wfMessage( $msg, $params )->text() . "\n";
                }
        }

        /**
         * Set debug mode...
         * @param bool $debug
         */
        function setDebug( $debug ) {
                $this->mDebug = $debug;
        }

        /**
         * Set 'no updates' mode. In this mode, the link tables will not be updated by the importer
         * @param bool $noupdates
         */
        function setNoUpdates( $noupdates ) {
                $this->mNoUpdates = $noupdates;
        }

        /**
         * Set a callback that displays notice messages
         *
         * @param callable $callback
         * @return callable
         */
        public function setNoticeCallback( $callback ) {
                return wfSetVar( $this->mNoticeCallback, $callback );
        }

        /**
         * Sets the action to perform as each new page in the stream is reached.
         * @param callable $callback
         * @return callable
         */
        public function setPageCallback( $callback ) {
                $previous = $this->mPageCallback;
                $this->mPageCallback = $callback;
                return $previous;
        }

        /**
         * Sets the action to perform as each page in the stream is completed.
         * Callback accepts the page title (as a Title object), a second object
         * with the original title form (in case it's been overridden into a
         * local namespace), and a count of revisions.
         *
         * @param callable $callback
         * @return callable
         */
        public function setPageOutCallback( $callback ) {
                $previous = $this->mPageOutCallback;
                $this->mPageOutCallback = $callback;
                return $previous;
        }

        /**
         * Sets the action to perform as each page revision is reached.
         * @param callable $callback
         * @return callable
         */
        public function setRevisionCallback( $callback ) {
                $previous = $this->mRevisionCallback;
                $this->mRevisionCallback = $callback;
                return $previous;
        }

        /**
         * Sets the action to perform as each file upload version is reached.
         * @param callable $callback
         * @return callable
         */
        public function setUploadCallback( $callback ) {
                $previous = $this->mUploadCallback;
                $this->mUploadCallback = $callback;
                return $previous;
        }

        /**
         * Sets the action to perform as each log item reached.
         * @param callable $callback
         * @return callable
         */
        public function setLogItemCallback( $callback ) {
                $previous = $this->mLogItemCallback;
                $this->mLogItemCallback = $callback;
                return $previous;
        }

        /**
         * Sets the action to perform when site info is encountered
         * @param callable $callback
         * @return callable
         */
        public function setSiteInfoCallback( $callback ) {
                $previous = $this->mSiteInfoCallback;
                $this->mSiteInfoCallback = $callback;
                return $previous;
        }

        /**
         * Sets the factory object to use to convert ForeignTitle objects into local
         * Title objects
         * @param ImportTitleFactory $factory
         */
        public function setImportTitleFactory( $factory ) {
                $this->importTitleFactory = $factory;
        }

        /**
         * Set a target namespace to override the defaults
         * @param null|int $namespace
         * @return bool
         */
        public function setTargetNamespace( $namespace ) {
                if ( is_null( $namespace ) ) {
                        // Don't override namespaces
                        $this->setImportTitleFactory( new NaiveImportTitleFactory() );
                        return true;
                } elseif (
                        $namespace >= 0 &&
                        MWNamespace::exists( intval( $namespace ) )
                ) {
                        $namespace = intval( $namespace );
                        $this->setImportTitleFactory( new NamespaceImportTitleFactory( $namespace ) );
                        return true;
                } else {
                        return false;
                }
        }

        /**
         * Set a target root page under which all pages are imported
         * @param null|string $rootpage
         * @return Status
         */
        public function setTargetRootPage( $rootpage ) {
                $status = Status::newGood();
                if ( is_null( $rootpage ) ) {
                        // No rootpage
                        $this->setImportTitleFactory( new NaiveImportTitleFactory() );
                } elseif ( $rootpage !== '' ) {
                        $rootpage = rtrim( $rootpage, '/' ); // avoid double slashes
                        $title = Title::newFromText( $rootpage );

                        if ( !$title || $title->isExternal() ) {
                                $status->fatal( 'import-rootpage-invalid' );
                        } else {
                                if ( !MWNamespace::hasSubpages( $title->getNamespace() ) ) {
                                        global $wgContLang;

                                        $displayNSText = $title->getNamespace() == NS_MAIN
                                                ? wfMessage( 'blanknamespace' )->text()
                                                : $wgContLang->getNsText( $title->getNamespace() );
                                        $status->fatal( 'import-rootpage-nosubpage', $displayNSText );
                                } else {
                                        // set namespace to 'all', so the namespace check in processTitle() can pass
                                        $this->setTargetNamespace( null );
                                        $this->setImportTitleFactory( new SubpageImportTitleFactory( $title ) );
                                }
                        }
                }
                return $status;
        }

        /**
         * @param string $dir
         */
        public function setImageBasePath( $dir ) {
                $this->mImageBasePath = $dir;
        }

        /**
         * @param bool $import
         */
        public function setImportUploads( $import ) {
                $this->mImportUploads = $import;
        }

        /**
         * Statistics update can cause a lot of time
         * @since 1.29
         */
        public function disableStatisticsUpdate() {
                $this->disableStatisticsUpdate = true;
        }

        /**
         * Default per-page callback. Sets up some things related to site statistics
         * @param array $titleAndForeignTitle Two-element array, with Title object at
         * index 0 and ForeignTitle object at index 1
         * @return bool
         */
        public function beforeImportPage( $titleAndForeignTitle ) {
                $title = $titleAndForeignTitle[0];
                $page = WikiPage::factory( $title );
                $this->countableCache['title_' . $title->getPrefixedText()] = $page->isCountable();
                return true;
        }

        /**
         * Default per-revision callback, performs the import.
         * @param WikiRevision $revision
         * @return bool
         */
        public function importRevision( $revision ) {
                if ( !$revision->getContentHandler()->canBeUsedOn( $revision->getTitle() ) ) {
                        $this->notice( 'import-error-bad-location',
                                $revision->getTitle()->getPrefixedText(),
                                $revision->getID(),
                                $revision->getModel(),
                                $revision->getFormat() );

                        return false;
                }

                try {
                        return $revision->importOldRevision();
                } catch ( MWContentSerializationException $ex ) {
                        $this->notice( 'import-error-unserialize',
                                $revision->getTitle()->getPrefixedText(),
                                $revision->getID(),
                                $revision->getModel(),
                                $revision->getFormat() );
                }

                return false;
        }

        /**
         * Default per-revision callback, performs the import.
         * @param WikiRevision $revision
         * @return bool
         */
        public function importLogItem( $revision ) {
                return $revision->importLogItem();
        }

        /**
         * Dummy for now...
         * @param WikiRevision $revision
         * @return bool
         */
        public function importUpload( $revision ) {
                return $revision->importUpload();
        }

        /**
         * Mostly for hook use
         * @param Title $title
         * @param ForeignTitle $foreignTitle
         * @param int $revCount
         * @param int $sRevCount
         * @param array $pageInfo
         * @return bool
         */
        public function finishImportPage( $title, $foreignTitle, $revCount,
                        $sRevCount, $pageInfo ) {

                // Update article count statistics (T42009)
                // The normal counting logic in WikiPage->doEditUpdates() is designed for
                // one-revision-at-a-time editing, not bulk imports. In this situation it
                // suffers from issues of replica DB lag. We let WikiPage handle the total page
                // and revision count, and we implement our own custom logic for the
                // article (content page) count.
                if ( !$this->disableStatisticsUpdate ) {
                        $page = WikiPage::factory( $title );
                        $page->loadPageData( 'fromdbmaster' );
                        $content = $page->getContent();
                        if ( $content === null ) {
                                wfDebug( __METHOD__ . ': Skipping article count adjustment for ' . $title .
                                        ' because WikiPage::getContent() returned null' );
                        } else {
                                $editInfo = $page->prepareContentForEdit( $content );
                                $countKey = 'title_' . $title->getPrefixedText();
                                $countable = $page->isCountable( $editInfo );
                                if ( array_key_exists( $countKey, $this->countableCache ) &&
                                        $countable != $this->countableCache[$countKey] ) {
                                        DeferredUpdates::addUpdate( SiteStatsUpdate::factory( [
                                                'articles' => ( (int)$countable - (int)$this->countableCache[$countKey] )
                                        ] ) );
                                }
                        }
                }

                $args = func_get_args();
                return Hooks::run( 'AfterImportPage', $args );
        }

        /**
         * Alternate per-revision callback, for debugging.
         * @param WikiRevision $revision
         */
        public function debugRevisionHandler( &$revision ) {
                $this->debug( "Got revision:" );
                if ( is_object( $revision->title ) ) {
                        $this->debug( "-- Title: " . $revision->title->getPrefixedText() );
                } else {
                        $this->debug( "-- Title: <invalid>" );
                }
                $this->debug( "-- User: " . $revision->user_text );
                $this->debug( "-- Timestamp: " . $revision->timestamp );
                $this->debug( "-- Comment: " . $revision->comment );
                $this->debug( "-- Text: " . $revision->text );
        }

        /**
         * Notify the callback function of site info
         * @param array $siteInfo
         * @return bool|mixed
         */
        private function siteInfoCallback( $siteInfo ) {
                if ( isset( $this->mSiteInfoCallback ) ) {
                        return call_user_func_array( $this->mSiteInfoCallback,
                                        [ $siteInfo, $this ] );
                } else {
                        return false;
                }
        }

        /**
         * Notify the callback function when a new "<page>" is reached.
         * @param Title $title
         */
        function pageCallback( $title ) {
                if ( isset( $this->mPageCallback ) ) {
                        call_user_func( $this->mPageCallback, $title );
                }
        }

        /**
         * Notify the callback function when a "</page>" is closed.
         * @param Title $title
         * @param ForeignTitle $foreignTitle
         * @param int $revCount
         * @param int $sucCount Number of revisions for which callback returned true
         * @param array $pageInfo Associative array of page information
         */
        private function pageOutCallback( $title, $foreignTitle, $revCount,
                        $sucCount, $pageInfo ) {
                if ( isset( $this->mPageOutCallback ) ) {
                        $args = func_get_args();
                        call_user_func_array( $this->mPageOutCallback, $args );
                }
        }

        /**
         * Notify the callback function of a revision
         * @param WikiRevision $revision
         * @return bool|mixed
         */
        private function revisionCallback( $revision ) {
                if ( isset( $this->mRevisionCallback ) ) {
                        return call_user_func_array( $this->mRevisionCallback,
                                        [ $revision, $this ] );
                } else {
                        return false;
                }
        }

        /**
         * Notify the callback function of a new log item
         * @param WikiRevision $revision
         * @return bool|mixed
         */
        private function logItemCallback( $revision ) {
                if ( isset( $this->mLogItemCallback ) ) {
                        return call_user_func_array( $this->mLogItemCallback,
                                        [ $revision, $this ] );
                } else {
                        return false;
                }
        }

        /**
         * Retrieves the contents of the named attribute of the current element.
         * @param string $attr The name of the attribute
         * @return string The value of the attribute or an empty string if it is not set in the current
         * element.
         */
        public function nodeAttribute( $attr ) {
                return $this->reader->getAttribute( $attr );
        }

        /**
         * Shouldn't something like this be built-in to XMLReader?
         * Fetches text contents of the current element, assuming
         * no sub-elements or such scary things.
         * @return string
         * @access private
         */
        public function nodeContents() {
                if ( $this->reader->isEmptyElement ) {
                        return "";
                }
                $buffer = "";
                while ( $this->reader->read() ) {
                        switch ( $this->reader->nodeType ) {
                        case XMLReader::TEXT:
                        case XMLReader::CDATA:
                        case XMLReader::SIGNIFICANT_WHITESPACE:
                                $buffer .= $this->reader->value;
                                break;
                        case XMLReader::END_ELEMENT:
                                return $buffer;
                        }
                }

                $this->reader->close();
                return '';
        }

        /**
         * Primary entry point
         * @throws MWException
         * @return bool
         */
        public function doImport() {
                // Calls to reader->read need to be wrapped in calls to
                // libxml_disable_entity_loader() to avoid local file
                // inclusion attacks (bug 46932).
                $oldDisable = libxml_disable_entity_loader( true );
                $this->reader->read();

                if ( $this->reader->localName != 'mediawiki' ) {
                        libxml_disable_entity_loader( $oldDisable );
                        throw new MWException( "Expected <mediawiki> tag, got " .
                                $this->reader->localName );
                }
                $this->debug( "<mediawiki> tag is correct." );

                $this->debug( "Starting primary dump processing loop." );

                $keepReading = $this->reader->read();
                $skip = false;
                $rethrow = null;
                try {
                        while ( $keepReading ) {
                                $tag = $this->reader->localName;
                                $type = $this->reader->nodeType;

                                if ( !Hooks::run( 'ImportHandleToplevelXMLTag', [ $this ] ) ) {
                                        // Do nothing
                                } elseif ( $tag == 'mediawiki' && $type == XMLReader::END_ELEMENT ) {
                                        break;
                                } elseif ( $tag == 'siteinfo' ) {
                                        $this->handleSiteInfo();
                                } elseif ( $tag == 'page' ) {
                                        $this->handlePage();
                                } elseif ( $tag == 'logitem' ) {
                                        $this->handleLogItem();
                                } elseif ( $tag != '#text' ) {
                                        $this->warn( "Unhandled top-level XML tag $tag" );

                                        $skip = true;
                                }

                                if ( $skip ) {
                                        $keepReading = $this->reader->next();
                                        $skip = false;
                                        $this->debug( "Skip" );
                                } else {
                                        $keepReading = $this->reader->read();
                                }
                        }
                } catch ( Exception $ex ) {
                        $rethrow = $ex;
                }

                // finally
                libxml_disable_entity_loader( $oldDisable );
                $this->reader->close();

                if ( $rethrow ) {
                        throw $rethrow;
                }

                return true;
        }

        private function handleSiteInfo() {
                $this->debug( "Enter site info handler." );
                $siteInfo = [];

                // Fields that can just be stuffed in the siteInfo object
                $normalFields = [ 'sitename', 'base', 'generator', 'case' ];

                while ( $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'siteinfo' ) {
                                break;
                        }

                        $tag = $this->reader->localName;

                        if ( $tag == 'namespace' ) {
                                $this->foreignNamespaces[$this->nodeAttribute( 'key' )] =
                                        $this->nodeContents();
                        } elseif ( in_array( $tag, $normalFields ) ) {
                                $siteInfo[$tag] = $this->nodeContents();
                        }
                }

                $siteInfo['_namespaces'] = $this->foreignNamespaces;
                $this->siteInfoCallback( $siteInfo );
        }

        private function handleLogItem() {
                $this->debug( "Enter log item handler." );
                $logInfo = [];

                // Fields that can just be stuffed in the pageInfo object
                $normalFields = [ 'id', 'comment', 'type', 'action', 'timestamp',
                                        'logtitle', 'params' ];

                while ( $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'logitem' ) {
                                break;
                        }

                        $tag = $this->reader->localName;

                        if ( !Hooks::run( 'ImportHandleLogItemXMLTag', [
                                $this, $logInfo
                        ] ) ) {
                                // Do nothing
                        } elseif ( in_array( $tag, $normalFields ) ) {
                                $logInfo[$tag] = $this->nodeContents();
                        } elseif ( $tag == 'contributor' ) {
                                $logInfo['contributor'] = $this->handleContributor();
                        } elseif ( $tag != '#text' ) {
                                $this->warn( "Unhandled log-item XML tag $tag" );
                        }
                }

                $this->processLogItem( $logInfo );
        }

        /**
         * @param array $logInfo
         * @return bool|mixed
         */
        private function processLogItem( $logInfo ) {

                $revision = new WikiRevision( $this->config );

                if ( isset( $logInfo['id'] ) ) {
                        $revision->setID( $logInfo['id'] );
                }
                $revision->setType( $logInfo['type'] );
                $revision->setAction( $logInfo['action'] );
                if ( isset( $logInfo['timestamp'] ) ) {
                        $revision->setTimestamp( $logInfo['timestamp'] );
                }
                if ( isset( $logInfo['params'] ) ) {
                        $revision->setParams( $logInfo['params'] );
                }
                if ( isset( $logInfo['logtitle'] ) ) {
                        // @todo Using Title for non-local titles is a recipe for disaster.
                        // We should use ForeignTitle here instead.
                        $revision->setTitle( Title::newFromText( $logInfo['logtitle'] ) );
                }

                $revision->setNoUpdates( $this->mNoUpdates );

                if ( isset( $logInfo['comment'] ) ) {
                        $revision->setComment( $logInfo['comment'] );
                }

                if ( isset( $logInfo['contributor']['ip'] ) ) {
                        $revision->setUserIP( $logInfo['contributor']['ip'] );
                }

                if ( !isset( $logInfo['contributor']['username'] ) ) {
                        $revision->setUsername( 'Unknown user' );
                } else {
                        $revision->setUsername( $logInfo['contributor']['username'] );
                }

                return $this->logItemCallback( $revision );
        }

        private function handlePage() {
                // Handle page data.
                $this->debug( "Enter page handler." );
                $pageInfo = [ 'revisionCount' => 0, 'successfulRevisionCount' => 0 ];

                // Fields that can just be stuffed in the pageInfo object
                $normalFields = [ 'title', 'ns', 'id', 'redirect', 'restrictions' ];

                $skip = false;
                $badTitle = false;

                while ( $skip ? $this->reader->next() : $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'page' ) {
                                break;
                        }

                        $skip = false;

                        $tag = $this->reader->localName;

                        if ( $badTitle ) {
                                // The title is invalid, bail out of this page
                                $skip = true;
                        } elseif ( !Hooks::run( 'ImportHandlePageXMLTag', [ $this,
                                                &$pageInfo ] ) ) {
                                // Do nothing
                        } elseif ( in_array( $tag, $normalFields ) ) {
                                // An XML snippet:
                                // <page>
                                //     <id>123</id>
                                //     <title>Page</title>
                                //     <redirect title="NewTitle"/>
                                //     ...
                                // Because the redirect tag is built differently, we need special handling for that case.
                                if ( $tag == 'redirect' ) {
                                        $pageInfo[$tag] = $this->nodeAttribute( 'title' );
                                } else {
                                        $pageInfo[$tag] = $this->nodeContents();
                                }
                        } elseif ( $tag == 'revision' || $tag == 'upload' ) {
                                if ( !isset( $title ) ) {
                                        $title = $this->processTitle( $pageInfo['title'],
                                                isset( $pageInfo['ns'] ) ? $pageInfo['ns'] : null );

                                        // $title is either an array of two titles or false.
                                        if ( is_array( $title ) ) {
                                                $this->pageCallback( $title );
                                                list( $pageInfo['_title'], $foreignTitle ) = $title;
                                        } else {
                                                $badTitle = true;
                                                $skip = true;
                                        }
                                }

                                if ( $title ) {
                                        if ( $tag == 'revision' ) {
                                                $this->handleRevision( $pageInfo );
                                        } else {
                                                $this->handleUpload( $pageInfo );
                                        }
                                }
                        } elseif ( $tag != '#text' ) {
                                $this->warn( "Unhandled page XML tag $tag" );
                                $skip = true;
                        }
                }

                // @note $pageInfo is only set if a valid $title is processed above with
                //       no error. If we have a valid $title, then pageCallback is called
                //       above, $pageInfo['title'] is set and we do pageOutCallback here.
                //       If $pageInfo['_title'] is not set, then $foreignTitle is also not
                //       set since they both come from $title above.
                if ( array_key_exists( '_title', $pageInfo ) ) {
                        $this->pageOutCallback( $pageInfo['_title'], $foreignTitle,
                                        $pageInfo['revisionCount'],
                                        $pageInfo['successfulRevisionCount'],
                                        $pageInfo );
                }
        }

        /**
         * @param array $pageInfo
         */
        private function handleRevision( &$pageInfo ) {
                $this->debug( "Enter revision handler" );
                $revisionInfo = [];

                $normalFields = [ 'id', 'timestamp', 'comment', 'minor', 'model', 'format', 'text' ];

                $skip = false;

                while ( $skip ? $this->reader->next() : $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'revision' ) {
                                break;
                        }

                        $tag = $this->reader->localName;

                        if ( !Hooks::run( 'ImportHandleRevisionXMLTag', [
                                $this, $pageInfo, $revisionInfo
                        ] ) ) {
                                // Do nothing
                        } elseif ( in_array( $tag, $normalFields ) ) {
                                $revisionInfo[$tag] = $this->nodeContents();
                        } elseif ( $tag == 'contributor' ) {
                                $revisionInfo['contributor'] = $this->handleContributor();
                        } elseif ( $tag != '#text' ) {
                                $this->warn( "Unhandled revision XML tag $tag" );
                                $skip = true;
                        }
                }

                $pageInfo['revisionCount']++;
                if ( $this->processRevision( $pageInfo, $revisionInfo ) ) {
                        $pageInfo['successfulRevisionCount']++;
                }
        }

        /**
         * @param array $pageInfo
         * @param array $revisionInfo
         * @return bool|mixed
         */
        private function processRevision( $pageInfo, $revisionInfo ) {
                global $wgMaxArticleSize;

                // Make sure revisions won't violate $wgMaxArticleSize, which could lead to
                // database errors and instability. Testing for revisions with only listed
                // content models, as other content models might use serialization formats
                // which aren't checked against $wgMaxArticleSize.
                if ( ( !isset( $revisionInfo['model'] ) ||
                        in_array( $revisionInfo['model'], [
                                'wikitext',
                                'css',
                                'json',
                                'javascript',
                                'text',
                                ''
                        ] ) ) &&
                        strlen( $revisionInfo['text'] ) > $wgMaxArticleSize * 1024
                ) {
                        throw new MWException( 'The text of ' .
                                ( isset( $revisionInfo['id'] ) ?
                                        "the revision with ID $revisionInfo[id]" :
                                        'a revision'
                                ) . " exceeds the maximum allowable size ($wgMaxArticleSize KB)" );
                }

                $revision = new WikiRevision( $this->config );

                if ( isset( $revisionInfo['id'] ) ) {
                        $revision->setID( $revisionInfo['id'] );
                }
                if ( isset( $revisionInfo['model'] ) ) {
                        $revision->setModel( $revisionInfo['model'] );
                }
                if ( isset( $revisionInfo['format'] ) ) {
                        $revision->setFormat( $revisionInfo['format'] );
                }
                $revision->setTitle( $pageInfo['_title'] );

                if ( isset( $revisionInfo['text'] ) ) {
                        $handler = $revision->getContentHandler();
                        $text = $handler->importTransform(
                                $revisionInfo['text'],
                                $revision->getFormat() );

                        $revision->setText( $text );
                }
                if ( isset( $revisionInfo['timestamp'] ) ) {
                        $revision->setTimestamp( $revisionInfo['timestamp'] );
                } else {
                        $revision->setTimestamp( wfTimestampNow() );
                }

                if ( isset( $revisionInfo['comment'] ) ) {
                        $revision->setComment( $revisionInfo['comment'] );
                }

                if ( isset( $revisionInfo['minor'] ) ) {
                        $revision->setMinor( true );
                }
                if ( isset( $revisionInfo['contributor']['ip'] ) ) {
                        $revision->setUserIP( $revisionInfo['contributor']['ip'] );
                } elseif ( isset( $revisionInfo['contributor']['username'] ) ) {
                        $revision->setUsername( $revisionInfo['contributor']['username'] );
                } else {
                        $revision->setUsername( 'Unknown user' );
                }
                $revision->setNoUpdates( $this->mNoUpdates );

                return $this->revisionCallback( $revision );
        }

        /**
         * @param array $pageInfo
         * @return mixed
         */
        private function handleUpload( &$pageInfo ) {
                $this->debug( "Enter upload handler" );
                $uploadInfo = [];

                $normalFields = [ 'timestamp', 'comment', 'filename', 'text',
                                        'src', 'size', 'sha1base36', 'archivename', 'rel' ];

                $skip = false;

                while ( $skip ? $this->reader->next() : $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'upload' ) {
                                break;
                        }

                        $tag = $this->reader->localName;

                        if ( !Hooks::run( 'ImportHandleUploadXMLTag', [
                                $this, $pageInfo
                        ] ) ) {
                                // Do nothing
                        } elseif ( in_array( $tag, $normalFields ) ) {
                                $uploadInfo[$tag] = $this->nodeContents();
                        } elseif ( $tag == 'contributor' ) {
                                $uploadInfo['contributor'] = $this->handleContributor();
                        } elseif ( $tag == 'contents' ) {
                                $contents = $this->nodeContents();
                                $encoding = $this->reader->getAttribute( 'encoding' );
                                if ( $encoding === 'base64' ) {
                                        $uploadInfo['fileSrc'] = $this->dumpTemp( base64_decode( $contents ) );
                                        $uploadInfo['isTempSrc'] = true;
                                }
                        } elseif ( $tag != '#text' ) {
                                $this->warn( "Unhandled upload XML tag $tag" );
                                $skip = true;
                        }
                }

                if ( $this->mImageBasePath && isset( $uploadInfo['rel'] ) ) {
                        $path = "{$this->mImageBasePath}/{$uploadInfo['rel']}";
                        if ( file_exists( $path ) ) {
                                $uploadInfo['fileSrc'] = $path;
                                $uploadInfo['isTempSrc'] = false;
                        }
                }

                if ( $this->mImportUploads ) {
                        return $this->processUpload( $pageInfo, $uploadInfo );
                }
        }

        /**
         * @param string $contents
         * @return string
         */
        private function dumpTemp( $contents ) {
                $filename = tempnam( wfTempDir(), 'importupload' );
                file_put_contents( $filename, $contents );
                return $filename;
        }

        /**
         * @param array $pageInfo
         * @param array $uploadInfo
         * @return mixed
         */
        private function processUpload( $pageInfo, $uploadInfo ) {
                $revision = new WikiRevision( $this->config );
                $text = isset( $uploadInfo['text'] ) ? $uploadInfo['text'] : '';

                $revision->setTitle( $pageInfo['_title'] );
                $revision->setID( $pageInfo['id'] );
                $revision->setTimestamp( $uploadInfo['timestamp'] );
                $revision->setText( $text );
                $revision->setFilename( $uploadInfo['filename'] );
                if ( isset( $uploadInfo['archivename'] ) ) {
                        $revision->setArchiveName( $uploadInfo['archivename'] );
                }
                $revision->setSrc( $uploadInfo['src'] );
                if ( isset( $uploadInfo['fileSrc'] ) ) {
                        $revision->setFileSrc( $uploadInfo['fileSrc'],
                                !empty( $uploadInfo['isTempSrc'] ) );
                }
                if ( isset( $uploadInfo['sha1base36'] ) ) {
                        $revision->setSha1Base36( $uploadInfo['sha1base36'] );
                }
                $revision->setSize( intval( $uploadInfo['size'] ) );
                $revision->setComment( $uploadInfo['comment'] );

                if ( isset( $uploadInfo['contributor']['ip'] ) ) {
                        $revision->setUserIP( $uploadInfo['contributor']['ip'] );
                }
                if ( isset( $uploadInfo['contributor']['username'] ) ) {
                        $revision->setUsername( $uploadInfo['contributor']['username'] );
                }
                $revision->setNoUpdates( $this->mNoUpdates );

                return call_user_func( $this->mUploadCallback, $revision );
        }

        /**
         * @return array
         */
        private function handleContributor() {
                $fields = [ 'id', 'ip', 'username' ];
                $info = [];

                if ( $this->reader->isEmptyElement ) {
                        return $info;
                }
                while ( $this->reader->read() ) {
                        if ( $this->reader->nodeType == XMLReader::END_ELEMENT &&
                                        $this->reader->localName == 'contributor' ) {
                                break;
                        }

                        $tag = $this->reader->localName;

                        if ( in_array( $tag, $fields ) ) {
                                $info[$tag] = $this->nodeContents();
                        }
                }

                return $info;
        }

        /**
         * @param string $text
         * @param string|null $ns
         * @return array|bool
         */
        private function processTitle( $text, $ns = null ) {
                if ( is_null( $this->foreignNamespaces ) ) {
                        $foreignTitleFactory = new NaiveForeignTitleFactory();
                } else {
                        $foreignTitleFactory = new NamespaceAwareForeignTitleFactory(
                                $this->foreignNamespaces );
                }

                $foreignTitle = $foreignTitleFactory->createForeignTitle( $text,
                        intval( $ns ) );

                $title = $this->importTitleFactory->createTitleFromForeignTitle(
                        $foreignTitle );

                $commandLineMode = $this->config->get( 'CommandLineMode' );
                if ( is_null( $title ) ) {
                        # Invalid page title? Ignore the page
                        $this->notice( 'import-error-invalid', $foreignTitle->getFullText() );
                        return false;
                } elseif ( $title->isExternal() ) {
                        $this->notice( 'import-error-interwiki', $title->getPrefixedText() );
                        return false;
                } elseif ( !$title->canExist() ) {
                        $this->notice( 'import-error-special', $title->getPrefixedText() );
                        return false;
                } elseif ( !$title->userCan( 'edit' ) && !$commandLineMode ) {
                        # Do not import if the importing wiki user cannot edit this page
                        $this->notice( 'import-error-edit', $title->getPrefixedText() );
                        return false;
                } elseif ( !$title->exists() && !$title->userCan( 'create' ) && !$commandLineMode ) {
                        # Do not import if the importing wiki user cannot create this page
                        $this->notice( 'import-error-create', $title->getPrefixedText() );
                        return false;
                }

                return [ $title, $foreignTitle ];
        }
}