UploadStash.php

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<?php
use MediaWiki\Context\RequestContext;
use MediaWiki\FileRepo\File\File;
use MediaWiki\FileRepo\FileRepo;
use MediaWiki\FileRepo\LocalRepo;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\User\UserIdentity;
 
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;
 
    public $repo;
 
    protected $files = [];
 
    protected $fileMetadata = [];
 
    protected $fileProps = [];
 
    private $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();
    }
 
    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];
    }
 
    public function getMetadata( $key ) {
        $this->getFile( $key );
 
        return $this->fileMetadata[$key];
    }
 
    public function getFileProps( $key ) {
        $this->getFile( $key );
 
        return $this->fileProps[$key];
    }
 
    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 );
    }
 
    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;
    }
 
    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 );
    }
 
    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();
 
        $this->files[$key]->remove();
 
        unset( $this->files[$key] );
        unset( $this->fileMetadata[$key] );
 
        return true;
    }
 
    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;
    }
 
    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;
    }
 
    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;
    }
 
    protected function initFile( $key ) {
        $file = new UploadStashFile(
            $this->repo,
            $this->fileMetadata[$key]['us_path'],
            $key,
            $this->fileMetadata[$key]['us_sha1'],
            $this->fileMetadata[$key]['us_mime'] ?? false
        );
        if ( $file->getSize() === 0 ) {
            throw new UploadStashZeroLengthFileException(
                wfMessage( 'uploadstash-zero-length' )
            );
        }
        $this->files[$key] = $file;
 
        return true;
    }
}