SpecialUploadStash.php

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<?php
class SpecialUploadStash extends UnlistedSpecialPage {
        // UploadStash
        private $stash;

        // Since we are directly writing the file to STDOUT,
        // we should not be reading in really big files and serving them out.
        //
        // We also don't want people using this as a file drop, even if they
        // share credentials.
        //
        // This service is really for thumbnails and other such previews while
        // uploading.
        const MAX_SERVE_BYTES = 1048576; // 1MB

        public function __construct() {
                parent::__construct( 'UploadStash', 'upload' );
                try {
                        $this->stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash();
                } catch ( UploadStashNotAvailableException $e ) {
                }
        }

        public function execute( $subPage ) {
                $this->checkPermissions();

                if ( $subPage === null || $subPage === '' ) {
                        return $this->showUploads();
                }
                return $this->showUpload( $subPage );
        }

        public function showUpload( $key ) {
                // prevent callers from doing standard HTML output -- we'll take it from here
                $this->getOutput()->disable();

                try {
                        $params = $this->parseKey( $key );
                        if ( $params['type'] === 'thumb' ) {
                                return $this->outputThumbFromStash( $params['file'], $params['params'] );
                        } else {
                                return $this->outputLocalFile( $params['file'] );
                        }
                } catch( UploadStashFileNotFoundException $e ) {
                        $code = 404;
                        $message = $e->getMessage();
                } catch( UploadStashZeroLengthFileException $e ) {
                        $code = 500;
                        $message = $e->getMessage();
                } catch( UploadStashBadPathException $e ) {
                        $code = 500;
                        $message = $e->getMessage();
                } catch( SpecialUploadStashTooLargeException $e ) {
                        $code = 500;
                        $message = 'Cannot serve a file larger than ' . self::MAX_SERVE_BYTES . ' bytes. ' . $e->getMessage();
                } catch( Exception $e ) {
                        $code = 500;
                        $message = $e->getMessage();
                }

                throw new HttpError( $code, $message );
        }

        private function parseKey( $key ) {
                $type = strtok( $key, '/' );

                if ( $type !== 'file' && $type !== 'thumb' ) {
                        throw new UploadStashBadPathException( "Unknown type '$type'" );
                }
                $fileName = strtok( '/' );
                $thumbPart = strtok( '/' );
                $file = $this->stash->getFile( $fileName );
                if ( $type === 'thumb' ) {
                        $srcNamePos = strrpos( $thumbPart, $fileName );
                        if ( $srcNamePos === false || $srcNamePos < 1 ) {
                                throw new UploadStashBadPathException( 'Unrecognized thumb name' );
                        }
                        $paramString = substr( $thumbPart, 0, $srcNamePos - 1 );

                        $handler = $file->getHandler();
                        $params = $handler->parseParamString( $paramString );
                        return array( 'file' => $file, 'type' => $type, 'params' => $params );
                }

                return array( 'file' => $file, 'type' => $type );
        }

        private function outputThumbFromStash( $file, $params ) {

                // this global, if it exists, points to a "scaler", as you might find in the Wikimedia Foundation cluster. See outputRemoteScaledThumb()
                // this is part of our horrible NFS-based system, we create a file on a mount point here, but fetch the scaled file from somewhere else that
                // happens to share it over NFS
                global $wgUploadStashScalerBaseUrl;

                $flags = 0;
                if ( $wgUploadStashScalerBaseUrl ) {
                        $this->outputRemoteScaledThumb( $file, $params, $flags );
                } else {
                        $this->outputLocallyScaledThumb( $file, $params, $flags );
                }
        }

        private function outputLocallyScaledThumb( $file, $params, $flags ) {

                // n.b. this is stupid, we insist on re-transforming the file every time we are invoked. We rely
                // on HTTP caching to ensure this doesn't happen.

                $flags |= File::RENDER_NOW;

                $thumbnailImage = $file->transform( $params, $flags );
                if ( !$thumbnailImage ) {
                        throw new MWException( 'Could not obtain thumbnail' );
                }

                // we should have just generated it locally
                if ( !$thumbnailImage->getStoragePath() ) {
                        throw new UploadStashFileNotFoundException( "no local path for scaled item" );
                }

                // now we should construct a File, so we can get mime and other such info in a standard way
                // n.b. mimetype may be different from original (ogx original -> jpeg thumb)
                $thumbFile = new UnregisteredLocalFile( false, 
                        $this->stash->repo, $thumbnailImage->getStoragePath(), false );
                if ( !$thumbFile ) {
                        throw new UploadStashFileNotFoundException( "couldn't create local file object for thumbnail" );
                }

                return $this->outputLocalFile( $thumbFile );

        }

        private function outputRemoteScaledThumb( $file, $params, $flags ) {

                // this global probably looks something like 'http://upload.wikimedia.org/wikipedia/test/thumb/temp'
                // do not use trailing slash
                global $wgUploadStashScalerBaseUrl;
                $scalerBaseUrl = $wgUploadStashScalerBaseUrl;

                if( preg_match( '/^\/\//', $scalerBaseUrl ) ) {
                        // this is apparently a protocol-relative URL, which makes no sense in this context,
                        // since this is used for communication that's internal to the application.
                        // default to http.
                        $scalerBaseUrl = wfExpandUrl( $scalerBaseUrl, PROTO_CANONICAL );
                }

                // We need to use generateThumbName() instead of thumbName(), because
                // the suffix needs to match the file name for the remote thumbnailer
                // to work
                $scalerThumbName = $file->generateThumbName( $file->getName(), $params );
                $scalerThumbUrl = $scalerBaseUrl . '/' . $file->getUrlRel() .
                        '/' . rawurlencode( $scalerThumbName );

                // make a curl call to the scaler to create a thumbnail
                $httpOptions = array(
                        'method' => 'GET',
                        'timeout' => 'default'
                );
                $req = MWHttpRequest::factory( $scalerThumbUrl, $httpOptions );
                $status = $req->execute();
                if ( ! $status->isOK() ) {
                        $errors = $status->getErrorsArray();
                        $errorStr = "Fetching thumbnail failed: " . print_r( $errors, 1 );
                        $errorStr .= "\nurl = $scalerThumbUrl\n";
                        throw new MWException( $errorStr );
                }
                $contentType = $req->getResponseHeader( "content-type" );
                if ( ! $contentType ) {
                        throw new MWException( "Missing content-type header" );
                }
                return $this->outputContents( $req->getContent(), $contentType );
        }

        private function outputLocalFile( File $file ) {
                if ( $file->getSize() > self::MAX_SERVE_BYTES ) {
                        throw new SpecialUploadStashTooLargeException();
                }
                return $file->getRepo()->streamFile( $file->getPath(),
                        array( 'Content-Transfer-Encoding: binary',
                                'Expires: Sun, 17-Jan-2038 19:14:07 GMT' )
                );
        }

        private function outputContents( $content, $contentType ) {
                $size = strlen( $content );
                if ( $size > self::MAX_SERVE_BYTES ) {
                        throw new SpecialUploadStashTooLargeException();
                }
                self::outputFileHeaders( $contentType, $size );
                print $content;
                return true;
        }

        private static function outputFileHeaders( $contentType, $size ) {
                header( "Content-Type: $contentType", true );
                header( 'Content-Transfer-Encoding: binary', true );
                header( 'Expires: Sun, 17-Jan-2038 19:14:07 GMT', true );
                // Bug 53032 - It shouldn't be a problem here, but let's be safe and not cache
                header( 'Cache-Control: private' );
                header( "Content-Length: $size", true );
        }

        public static function tryClearStashedUploads( $formData ) {
                if ( isset( $formData['Clear'] ) ) {
                        $stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash();
                        wfDebug( "stash has: " . print_r( $stash->listFiles(), true ) );
                        if ( ! $stash->clear() ) {
                                return Status::newFatal( 'uploadstash-errclear' );
                        }
                }
                return Status::newGood();
        }

        private function showUploads( $status = null ) {
                if ( $status === null ) {
                        $status = Status::newGood();
                }

                // sets the title, etc.
                $this->setHeaders();
                $this->outputHeader();

                // create the form, which will also be used to execute a callback to process incoming form data
                // this design is extremely dubious, but supposedly HTMLForm is our standard now?

                $form = new HTMLForm( array(
                        'Clear' => array(
                                'type' => 'hidden',
                                'default' => true,
                                'name' => 'clear',
                        )
                ), $this->getContext(), 'clearStashedUploads' );
                $form->setSubmitCallback( array( __CLASS__ , 'tryClearStashedUploads' ) );
                $form->setTitle( $this->getTitle() );
                $form->setSubmitText( wfMsg( 'uploadstash-clear' ) );

                $form->prepareForm();
                $formResult = $form->tryAuthorizedSubmit();

                // show the files + form, if there are any, or just say there are none
                $refreshHtml = Html::element( 'a',
                        array( 'href' => $this->getTitle()->getLocalURL() ),
                        wfMsg( 'uploadstash-refresh' ) );
                $files = $this->stash->listFiles();
                if ( $files && count( $files ) ) {
                        sort( $files );
                        $fileListItemsHtml = '';
                        foreach ( $files as $file ) {
                                // TODO: Use Linker::link or even construct the list in plain wikitext
                                $fileListItemsHtml .= Html::rawElement( 'li', array(),
                                        Html::element( 'a', array( 'href' =>
                                                $this->getTitle( "file/$file" )->getLocalURL() ), $file )
                                );
                        }
                        $this->getOutput()->addHtml( Html::rawElement( 'ul', array(), $fileListItemsHtml ) );
                        $form->displayForm( $formResult );
                        $this->getOutput()->addHtml( Html::rawElement( 'p', array(), $refreshHtml ) );
                } else {
                        $this->getOutput()->addHtml( Html::rawElement( 'p', array(),
                                Html::element( 'span', array(), wfMsg( 'uploadstash-nofiles' ) )
                                . ' '
                                . $refreshHtml
                        ) );
                }

                return true;
        }
}

class SpecialUploadStashTooLargeException extends MWException {};