wikimedia/mediawiki-core

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includes/upload/UploadStash.php

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<?php
/**
 * Temporary storage for uploaded files.
 *
 * 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
 */

use MediaWiki\Context\RequestContext;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\User\UserIdentity;

/**
 * UploadStash is intended to accomplish a few things:
 *   - Enable applications to temporarily stash files without publishing them to
 *     the wiki.
 *      - Several parts of MediaWiki do this in similar ways: UploadBase,
 *        UploadWizard, and FirefoggChunkedExtension.
 *        And there are several that reimplement stashing from scratch, in
 *        idiosyncratic ways. The idea is to unify them all here.
 *        Mostly all of them are the same except for storing some custom fields,
 *        which we subsume into the data array.
 *   - Enable applications to find said files later, as long as the db table or
 *     temp files haven't been purged.
 *   - Enable the uploading user (and *ONLY* the uploading user) to access said
 *     files, and thumbnails of said files, via a URL. We accomplish this using
 *     a database table, with ownership checking as you might expect. See
 *     SpecialUploadStash, which implements a web interface to some files stored
 *     this way.
 *
 * UploadStash right now is *mostly* intended to show you one user's slice of
 * the entire stash. The user parameter is only optional because there are few
 * cases where we clean out the stash from an automated script. In the future we
 * might refactor this.
 *
 * UploadStash represents the entire stash of temporary files.
 * UploadStashFile is a filestore for the actual physical disk files.
 * UploadFromStash extends UploadBase, and represents a single stashed file as
 * it is moved from the stash to the regular file repository
 *
 * @ingroup Upload
 */
class UploadStash {
    // Format of the key for files -- has to be suitable as a filename itself (e.g. ab12cd34ef.jpg)
    public const KEY_FORMAT_REGEX = '/^[\w\-\.]+\.\w*$/';
    private const MAX_US_PROPS_SIZE = 65535;

    /**
     * repository that this uses to store temp files
     * public because we sometimes need to get a LocalFile within the same repo.
     *
     * @var LocalRepo
     */
    public $repo;

    /** @var array array of initialized repo objects */
    protected $files = [];

    /** @var array cache of the file metadata that's stored in the database */
    protected $fileMetadata = [];

    /** @var array fileprops cache */
    protected $fileProps = [];

    /** @var UserIdentity */
    private $user;

    /**
     * Represents a temporary filestore, with metadata in the database.
     * Designed to be compatible with the session stashing code in UploadBase
     * (should replace it eventually).
     *
     * @param FileRepo $repo
     * @param UserIdentity|null $user
     */
    public function __construct( FileRepo $repo, UserIdentity $user = null ) {
        // this might change based on wiki's configuration.
        $this->repo = $repo;

        // if a user was passed, use it. otherwise, attempt to use the global request context.
        // this keeps FileRepo from breaking when it creates an UploadStash object
        $this->user = $user ?? RequestContext::getMain()->getUser();
    }

    /**
     * Get a file and its metadata from the stash.
     * The noAuth param is a bit janky but is required for automated scripts
     * which clean out the stash.
     *
     * @param string $key Key under which file information is stored
     * @param bool $noAuth (optional) Don't check authentication. Used by maintenance scripts.
     * @throws UploadStashFileNotFoundException
     * @throws UploadStashNotLoggedInException
     * @throws UploadStashWrongOwnerException
     * @throws UploadStashBadPathException
     * @return UploadStashFile
     */
    public function getFile( $key, $noAuth = false ) {
        if ( !preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
            throw new UploadStashBadPathException(
                wfMessage( 'uploadstash-bad-path-bad-format', $key )
            );
        }

        if ( !$noAuth && !$this->user->isRegistered() ) {
            throw new UploadStashNotLoggedInException(
                wfMessage( 'uploadstash-not-logged-in' )
            );
        }

        if ( !isset( $this->fileMetadata[$key] ) ) {
            if ( !$this->fetchFileMetadata( $key ) ) {
                // If nothing was received, it's likely due to replication lag.
                // Check the primary DB to see if the record is there.
                $this->fetchFileMetadata( $key, DB_PRIMARY );
            }

            if ( !isset( $this->fileMetadata[$key] ) ) {
                throw new UploadStashFileNotFoundException(
                    wfMessage( 'uploadstash-file-not-found', $key )
                );
            }

            // create $this->files[$key]
            $this->initFile( $key );

            // fetch fileprops
            if (
                isset( $this->fileMetadata[$key]['us_props'] ) && strlen( $this->fileMetadata[$key]['us_props'] )
            ) {
                $this->fileProps[$key] = unserialize( $this->fileMetadata[$key]['us_props'] );
            } else { // b/c for rows with no us_props
                wfDebug( __METHOD__ . " fetched props for $key from file" );
                $path = $this->fileMetadata[$key]['us_path'];
                $this->fileProps[$key] = $this->repo->getFileProps( $path );
            }
        }

        if ( !$this->files[$key]->exists() ) {
            wfDebug( __METHOD__ . " tried to get file at $key, but it doesn't exist" );
            // @todo Is this not an UploadStashFileNotFoundException case?
            throw new UploadStashBadPathException(
                wfMessage( 'uploadstash-bad-path' )
            );
        }

        if ( !$noAuth && $this->fileMetadata[$key]['us_user'] != $this->user->getId() ) {
            throw new UploadStashWrongOwnerException(
                wfMessage( 'uploadstash-wrong-owner', $key )
            );
        }

        return $this->files[$key];
    }

    /**
     * Getter for file metadata.
     *
     * @param string $key Key under which file information is stored
     * @return array
     */
    public function getMetadata( $key ) {
        $this->getFile( $key );

        return $this->fileMetadata[$key];
    }

    /**
     * Getter for fileProps
     *
     * @param string $key Key under which file information is stored
     * @return array
     */
    public function getFileProps( $key ) {
        $this->getFile( $key );

        return $this->fileProps[$key];
    }

    /**
     * Stash a file in a temp directory and record that we did this in the
     * database, along with other metadata.
     *
     * @param string $path Path to file you want stashed
     * @param string|null $sourceType The type of upload that generated this file
     *   (currently, I believe, 'file' or null)
     * @param array|null $fileProps File props or null to regenerate
     * @throws UploadStashBadPathException
     * @throws UploadStashFileException
     * @throws UploadStashNotLoggedInException
     * @return UploadStashFile|null File, or null on failure
     */
    public function stashFile( $path, $sourceType = null, $fileProps = null ) {
        if ( !is_file( $path ) ) {
            wfDebug( __METHOD__ . " tried to stash file at '$path', but it doesn't exist" );
            throw new UploadStashBadPathException(
                wfMessage( 'uploadstash-bad-path' )
            );
        }

        // File props is expensive to generate for large files, so reuse if possible.
        if ( !$fileProps ) {
            $mwProps = new MWFileProps( MediaWikiServices::getInstance()->getMimeAnalyzer() );
            $fileProps = $mwProps->getPropsFromPath( $path, true );
        }
        wfDebug( __METHOD__ . " stashing file at '$path'" );

        // we will be initializing from some tmpnam files that don't have extensions.
        // most of MediaWiki assumes all uploaded files have good extensions. So, we fix this.
        $extension = self::getExtensionForPath( $path );
        if ( !preg_match( "/\\.\\Q$extension\\E$/", $path ) ) {
            $pathWithGoodExtension = "$path.$extension";
        } else {
            $pathWithGoodExtension = $path;
        }

        // If no key was supplied, make one.  a mysql insertid would be totally
        // reasonable here, except that for historical reasons, the key is this
        // random thing instead.  At least it's not guessable.
        // Some things that when combined will make a suitably unique key.
        // see: http://www.jwz.org/doc/mid.html
        [ $usec, $sec ] = explode( ' ', microtime() );
        $usec = substr( $usec, 2 );
        $key = Wikimedia\base_convert( $sec . $usec, 10, 36 ) . '.' .
            Wikimedia\base_convert( (string)mt_rand(), 10, 36 ) . '.' .
            $this->user->getId() . '.' .
            $extension;

        $this->fileProps[$key] = $fileProps;

        if ( !preg_match( self::KEY_FORMAT_REGEX, $key ) ) {
            throw new UploadStashBadPathException(
                wfMessage( 'uploadstash-bad-path-bad-format', $key )
            );
        }

        wfDebug( __METHOD__ . " key for '$path': $key" );

        // if not already in a temporary area, put it there
        $storeStatus = $this->repo->storeTemp( basename( $pathWithGoodExtension ), $path );

        if ( !$storeStatus->isOK() ) {
            // It is a convention in MediaWiki to only return one error per API
            // exception, even if multiple errors are available.[citation needed]
            // Pick the "first" thing that was wrong, preferring errors to warnings.
            // This is a bit lame, as we may have more info in the
            // $storeStatus and we're throwing it away, but to fix it means
            // redesigning API errors significantly.
            // $storeStatus->value just contains the virtual URL (if anything)
            // which is probably useless to the caller.
            foreach ( $storeStatus->getMessages( 'error' ) as $msg ) {
                throw new UploadStashFileException( $msg );
            }
            foreach ( $storeStatus->getMessages( 'warning' ) as $msg ) {
                throw new UploadStashFileException( $msg );
            }
            // XXX: This isn't a real message, hopefully this case is unreachable
            throw new UploadStashFileException( [ 'unknown', 'no error recorded' ] );
        }
        $stashPath = $storeStatus->value;

        // fetch the current user ID
        if ( !$this->user->isRegistered() ) {
            throw new UploadStashNotLoggedInException(
                wfMessage( 'uploadstash-not-logged-in' )
            );
        }

        // insert the file metadata into the db.
        wfDebug( __METHOD__ . " inserting $stashPath under $key" );
        $dbw = $this->repo->getPrimaryDB();

        $serializedFileProps = serialize( $fileProps );
        if ( strlen( $serializedFileProps ) > self::MAX_US_PROPS_SIZE ) {
            // Database is going to truncate this and make the field invalid.
            // Prioritize important metadata over file handler metadata.
            // File handler should be prepared to regenerate invalid metadata if needed.
            $fileProps['metadata'] = [];
            $serializedFileProps = serialize( $fileProps );
        }

        $insertRow = [
            'us_user' => $this->user->getId(),
            'us_key' => $key,
            'us_orig_path' => $path,
            'us_path' => $stashPath, // virtual URL
            'us_props' => $dbw->encodeBlob( $serializedFileProps ),
            'us_size' => $fileProps['size'],
            'us_sha1' => $fileProps['sha1'],
            'us_mime' => $fileProps['mime'],
            'us_media_type' => $fileProps['media_type'],
            'us_image_width' => $fileProps['width'],
            'us_image_height' => $fileProps['height'],
            'us_image_bits' => $fileProps['bits'],
            'us_source_type' => $sourceType,
            'us_timestamp' => $dbw->timestamp(),
            'us_status' => 'finished'
        ];

        $dbw->newInsertQueryBuilder()
            ->insertInto( 'uploadstash' )
            ->row( $insertRow )
            ->caller( __METHOD__ )->execute();

        // store the insertid in the class variable so immediate retrieval
        // (possibly laggy) isn't necessary.
        $insertRow['us_id'] = $dbw->insertId();

        $this->fileMetadata[$key] = $insertRow;

        # create the UploadStashFile object for this file.
        $this->initFile( $key );

        return $this->getFile( $key );
    }

    /**
     * Remove all files from the stash.
     * Does not clean up files in the repo, just the record of them.
     *
     * @throws UploadStashNotLoggedInException
     * @return bool Success
     */
    public function clear() {
        if ( !$this->user->isRegistered() ) {
            throw new UploadStashNotLoggedInException(
                wfMessage( 'uploadstash-not-logged-in' )
            );
        }

        wfDebug( __METHOD__ . ' clearing all rows for user ' . $this->user->getId() );
        $dbw = $this->repo->getPrimaryDB();
        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'uploadstash' )
            ->where( [ 'us_user' => $this->user->getId() ] )
            ->caller( __METHOD__ )->execute();

        # destroy objects.
        $this->files = [];
        $this->fileMetadata = [];

        return true;
    }

    /**
     * Remove a particular file from the stash.  Also removes it from the repo.
     *
     * @param string $key
     * @throws UploadStashNoSuchKeyException|UploadStashNotLoggedInException
     * @throws UploadStashWrongOwnerException
     * @return bool Success
     */
    public function removeFile( $key ) {
        if ( !$this->user->isRegistered() ) {
            throw new UploadStashNotLoggedInException(
                wfMessage( 'uploadstash-not-logged-in' )
            );
        }

        $dbw = $this->repo->getPrimaryDB();

        // this is a cheap query. it runs on the primary DB so that this function
        // still works when there's lag. It won't be called all that often.
        $row = $dbw->newSelectQueryBuilder()
            ->select( 'us_user' )
            ->from( 'uploadstash' )
            ->where( [ 'us_key' => $key ] )
            ->caller( __METHOD__ )->fetchRow();

        if ( !$row ) {
            throw new UploadStashNoSuchKeyException(
                wfMessage( 'uploadstash-no-such-key', $key )
            );
        }

        if ( $row->us_user != $this->user->getId() ) {
            throw new UploadStashWrongOwnerException(
                wfMessage( 'uploadstash-wrong-owner', $key )
            );
        }

        return $this->removeFileNoAuth( $key );
    }

    /**
     * Remove a file (see removeFile), but doesn't check ownership first.
     *
     * @param string $key
     * @return bool Success
     */
    public function removeFileNoAuth( $key ) {
        wfDebug( __METHOD__ . " clearing row $key" );

        // Ensure we have the UploadStashFile loaded for this key
        $this->getFile( $key, true );

        $dbw = $this->repo->getPrimaryDB();

        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'uploadstash' )
            ->where( [ 'us_key' => $key ] )
            ->caller( __METHOD__ )->execute();

        /** @todo Look into UnregisteredLocalFile and find out why the rv here is
         *  sometimes wrong (false when file was removed). For now, ignore.
         */
        $this->files[$key]->remove();

        unset( $this->files[$key] );
        unset( $this->fileMetadata[$key] );

        return true;
    }

    /**
     * List all files in the stash.
     *
     * @throws UploadStashNotLoggedInException
     * @return array|false
     */
    public function listFiles() {
        if ( !$this->user->isRegistered() ) {
            throw new UploadStashNotLoggedInException(
                wfMessage( 'uploadstash-not-logged-in' )
            );
        }

        $res = $this->repo->getReplicaDB()->newSelectQueryBuilder()
            ->select( 'us_key' )
            ->from( 'uploadstash' )
            ->where( [ 'us_user' => $this->user->getId() ] )
            ->caller( __METHOD__ )->fetchResultSet();

        if ( $res->numRows() == 0 ) {
            // nothing to do.
            return false;
        }

        // finish the read before starting writes.
        $keys = [];
        foreach ( $res as $row ) {
            $keys[] = $row->us_key;
        }

        return $keys;
    }

    /**
     * Find or guess extension -- ensuring that our extension matches our MIME type.
     * Since these files are constructed from php tempnames they may not start off
     * with an extension.
     * XXX this is somewhat redundant with the checks that ApiUpload.php does with incoming
     * uploads versus the desired filename. Maybe we can get that passed to us...
     * @param string $path
     * @return string
     */
    public static function getExtensionForPath( $path ) {
        $prohibitedFileExtensions = MediaWikiServices::getInstance()
            ->getMainConfig()->get( MainConfigNames::ProhibitedFileExtensions );
        // Does this have an extension?
        $n = strrpos( $path, '.' );

        if ( $n !== false ) {
            $extension = $n ? substr( $path, $n + 1 ) : '';
        } else {
            // If not, assume that it should be related to the MIME type of the original file.
            $magic = MediaWikiServices::getInstance()->getMimeAnalyzer();
            $mimeType = $magic->guessMimeType( $path );
            $extension = $magic->getExtensionFromMimeTypeOrNull( $mimeType ) ?? '';
        }

        $extension = File::normalizeExtension( $extension );
        if ( in_array( $extension, $prohibitedFileExtensions ) ) {
            // The file should already be checked for being evil.
            // However, if somehow we got here, we definitely
            // don't want to give it an extension of .php and
            // put it in a web accessible directory.
            return '';
        }

        return $extension;
    }

    /**
     * Helper function: do the actual database query to fetch file metadata.
     *
     * @param string $key
     * @param int $readFromDB Constant (default: DB_REPLICA)
     * @return bool
     */
    protected function fetchFileMetadata( $key, $readFromDB = DB_REPLICA ) {
        // populate $fileMetadata[$key]
        if ( $readFromDB === DB_PRIMARY ) {
            // sometimes reading from the primary DB is necessary, if there's replication lag.
            $dbr = $this->repo->getPrimaryDB();
        } else {
            $dbr = $this->repo->getReplicaDB();
        }

        $row = $dbr->newSelectQueryBuilder()
            ->select( [
                'us_user', 'us_key', 'us_orig_path', 'us_path', 'us_props',
                'us_size', 'us_sha1', 'us_mime', 'us_media_type',
                'us_image_width', 'us_image_height', 'us_image_bits',
                'us_source_type', 'us_timestamp', 'us_status',
            ] )
            ->from( 'uploadstash' )
            ->where( [ 'us_key' => $key ] )
            ->caller( __METHOD__ )->fetchRow();

        if ( !is_object( $row ) ) {
            // key wasn't present in the database. this will happen sometimes.
            return false;
        }

        $this->fileMetadata[$key] = (array)$row;
        $this->fileMetadata[$key]['us_props'] = $dbr->decodeBlob( $row->us_props );

        return true;
    }

    /**
     * Helper function: Initialize the UploadStashFile for a given file.
     *
     * @param string $key Key under which to store the object
     * @throws UploadStashZeroLengthFileException
     * @return bool
     */
    protected function initFile( $key ) {
        $file = new UploadStashFile(
            $this->repo,
            $this->fileMetadata[$key]['us_path'],
            $key,
            $this->fileMetadata[$key]['us_sha1']
        );
        if ( $file->getSize() === 0 ) {
            throw new UploadStashZeroLengthFileException(
                wfMessage( 'uploadstash-zero-length' )
            );
        }
        $this->files[$key] = $file;

        return true;
    }
}