Special:Upload should not crash on failing previews

[mediawiki.git] / includes / specials / SpecialUploadStash.php

<?php
/**
 * Implements Special:UploadStash.
 *
 * 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
 * @ingroup Upload
 */

/**
 * Web access for files temporarily stored by UploadStash.
 *
 * For example -- files that were uploaded with the UploadWizard extension are stored temporarily
 * before committing them to the db. But we want to see their thumbnails and get other information
 * about them.
 *
 * Since this is based on the user's session, in effect this creates a private temporary file area.
 * However, the URLs for the files cannot be shared.
 */
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' );
        }

        public function doesWrites() {
                return true;
        }

        /**
         * Execute page -- can output a file directly or show a listing of them.
         *
         * @param string $subPage Subpage, e.g. in
         *   https://example.com/wiki/Special:UploadStash/foo.jpg, the "foo.jpg" part
         * @return bool Success
         */
        public function execute( $subPage ) {
                $this->useTransactionalTimeLimit();

                $this->stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash( $this->getUser() );
                $this->checkPermissions();

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

                return $this->showUpload( $subPage );
        }

        /**
         * If file available in stash, cats it out to the client as a simple HTTP response.
         * n.b. Most sanity checking done in UploadStashLocalFile, so this is straightforward.
         *
         * @param string $key The key of a particular requested file
         * @throws HttpError
         * @return bool
         */
        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 );
        }

        /**
         * Parse the key passed to the SpecialPage. Returns an array containing
         * the associated file object, the type ('file' or 'thumb') and if
         * application the transform parameters
         *
         * @param string $key
         * @throws UploadStashBadPathException
         * @return array
         */
        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();
                        if ( $handler ) {
                                $params = $handler->parseParamString( $paramString );

                                return [ 'file' => $file, 'type' => $type, 'params' => $params ];
                        } else {
                                throw new UploadStashBadPathException( 'No handler found for ' .
                                        "mime {$file->getMimeType()} of file {$file->getPath()}" );
                        }
                }

                return [ 'file' => $file, 'type' => $type ];
        }

        /**
         * Get a thumbnail for file, either generated locally or remotely, and stream it out
         *
         * @param File $file
         * @param array $params
         *
         * @return bool Success
         */
        private function outputThumbFromStash( $file, $params ) {
                $flags = 0;
                // this config option, 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.
                if ( $this->getConfig()->get( 'UploadStashScalerBaseUrl' ) ) {
                        $this->outputRemoteScaledThumb( $file, $params, $flags );
                } else {
                        $this->outputLocallyScaledThumb( $file, $params, $flags );
                }
        }

        /**
         * Scale a file (probably with a locally installed imagemagick, or similar)
         * and output it to STDOUT.
         * @param File $file
         * @param array $params Scaling parameters ( e.g. [ width => '50' ] );
         * @param int $flags Scaling flags ( see File:: constants )
         * @throws MWException|UploadStashFileNotFoundException
         * @return bool Success
         */
        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. MIME type 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 );
        }

        /**
         * Scale a file with a remote "scaler", as exists on the Wikimedia Foundation
         * cluster, and output it to STDOUT.
         * Note: Unlike the usual thumbnail process, the web client never sees the
         * cluster URL; we do the whole HTTP transaction to the scaler ourselves
         * and cat the results out.
         * Note: We rely on NFS to have propagated the file contents to the scaler.
         * However, we do not rely on the thumbnail being created in NFS and then
         * propagated back to our filesystem. Instead we take the results of the
         * HTTP request instead.
         * Note: No caching is being done here, although we are instructing the
         * client to cache it forever.
         *
         * @param File $file
         * @param array $params Scaling parameters ( e.g. [ width => '50' ] );
         * @param int $flags Scaling flags ( see File:: constants )
         * @throws MWException
         * @return bool Success
         */
        private function outputRemoteScaledThumb( $file, $params, $flags ) {
                // This option probably looks something like
                // '//upload.wikimedia.org/wikipedia/test/thumb/temp'. Do not use
                // trailing slash.
                $scalerBaseUrl = $this->getConfig()->get( 'UploadStashScalerBaseUrl' );

                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 = [
                        'method' => 'GET',
                        'timeout' => 5 // T90599 attempt to time out cleanly
                ];
                $req = MWHttpRequest::factory( $scalerThumbUrl, $httpOptions, __METHOD__ );
                $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 );
        }

        /**
         * Output HTTP response for file
         * Side effect: writes HTTP response to STDOUT.
         *
         * @param File $file File object with a local path (e.g. UnregisteredLocalFile,
         *   LocalFile. Oddly these don't share an ancestor!)
         * @throws SpecialUploadStashTooLargeException
         * @return bool
         */
        private function outputLocalFile( File $file ) {
                if ( $file->getSize() > self::MAX_SERVE_BYTES ) {
                        throw new SpecialUploadStashTooLargeException();
                }

                return $file->getRepo()->streamFile( $file->getPath(),
                        [ 'Content-Transfer-Encoding: binary',
                                'Expires: Sun, 17-Jan-2038 19:14:07 GMT' ]
                );
        }

        /**
         * Output HTTP response of raw content
         * Side effect: writes HTTP response to STDOUT.
         * @param string $content Content
         * @param string $contentType MIME type
         * @throws SpecialUploadStashTooLargeException
         * @return bool
         */
        private function outputContents( $content, $contentType ) {
                $size = strlen( $content );
                if ( $size > self::MAX_SERVE_BYTES ) {
                        throw new SpecialUploadStashTooLargeException();
                }
                // Cancel output buffering and gzipping if set
                wfResetOutputBuffers();
                self::outputFileHeaders( $contentType, $size );
                print $content;

                return true;
        }

        /**
         * Output headers for streaming
         * @todo Unsure about encoding as binary; if we received from HTTP perhaps
         * we should use that encoding, concatenated with semicolon to `$contentType` as it
         * usually is.
         * Side effect: preps PHP to write headers to STDOUT.
         * @param string $contentType String suitable for content-type header
         * @param string $size Length in bytes
         */
        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 );
        }

        /**
         * Static callback for the HTMLForm in showUploads, to process
         * Note the stash has to be recreated since this is being called in a static context.
         * This works, because there really is only one stash per logged-in user, despite appearances.
         *
         * @param array $formData
         * @param HTMLForm $form
         * @return Status
         */
        public static function tryClearStashedUploads( $formData, $form ) {
                if ( isset( $formData['Clear'] ) ) {
                        $stash = RepoGroup::singleton()->getLocalRepo()->getUploadStash( $form->getUser() );
                        wfDebug( 'stash has: ' . print_r( $stash->listFiles(), true ) . "\n" );

                        if ( !$stash->clear() ) {
                                return Status::newFatal( 'uploadstash-errclear' );
                        }
                }

                return Status::newGood();
        }

        /**
         * Default action when we don't have a subpage -- just show links to the uploads we have,
         * Also show a button to clear stashed files
         * @return bool
         */
        private function showUploads() {
                // 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?

                $context = new DerivativeContext( $this->getContext() );
                $context->setTitle( $this->getPageTitle() ); // Remove subpage
                $form = HTMLForm::factory( 'ooui', [
                        'Clear' => [
                                'type' => 'hidden',
                                'default' => true,
                                'name' => 'clear',
                        ]
                ], $context, 'clearStashedUploads' );
                $form->setSubmitDestructive();
                $form->setSubmitCallback( [ __CLASS__, 'tryClearStashedUploads' ] );
                $form->setSubmitTextMsg( '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',
                        [ 'href' => $this->getPageTitle()->getLocalURL() ],
                        $this->msg( 'uploadstash-refresh' )->text() );
                $files = $this->stash->listFiles();
                if ( $files && count( $files ) ) {
                        sort( $files );
                        $fileListItemsHtml = '';
                        $linkRenderer = $this->getLinkRenderer();
                        foreach ( $files as $file ) {
                                $itemHtml = $linkRenderer->makeKnownLink(
                                        $this->getPageTitle( "file/$file" ),
                                        $file
                                );
                                try {
                                        $fileObj = $this->stash->getFile( $file );
                                        $thumb = $fileObj->generateThumbName( $file, [ 'width' => 220 ] );
                                        $itemHtml .=
                                                $this->msg( 'word-separator' )->escaped() .
                                                $this->msg( 'parentheses' )->rawParams(
                                                        $linkRenderer->makeKnownLink(
                                                                $this->getPageTitle( "thumb/$file/$thumb" ),
                                                                $this->msg( 'uploadstash-thumbnail' )->text()
                                                        )
                                                )->escaped();
                                } catch ( Exception $e ) {
                                }
                                $fileListItemsHtml .= Html::rawElement( 'li', [], $itemHtml );
                        }
                        $this->getOutput()->addHTML( Html::rawElement( 'ul', [], $fileListItemsHtml ) );
                        $form->displayForm( $formResult );
                        $this->getOutput()->addHTML( Html::rawElement( 'p', [], $refreshHtml ) );
                } else {
                        $this->getOutput()->addHTML( Html::rawElement( 'p', [],
                                Html::element( 'span', [], $this->msg( 'uploadstash-nofiles' )->text() )
                                . ' '
                                . $refreshHtml
                        ) );
                }

                return true;
        }
}

class SpecialUploadStashTooLargeException extends MWException {
}