More cleanup from r22859

[mediawiki.git] / includes / filerepo / File.php

<?php

/**
 * Base file class. Do not instantiate.
 *
 * Implements some public methods and some protected utility functions which 
 * are required by multiple child classes. Contains stub functionality for 
 * unimplemented public methods.
 *
 * Stub functions which should be overridden are marked with STUB. Some more 
 * concrete functions are also typically overridden by child classes.
 *
 * Note that only the repo object knows what its file class is called. You should
 * never name a file class explictly outside of the repo class. Instead use the 
 * repo's factory functions to generate file objects, for example:
 *
 * RepoGroup::singleton()->getLocalRepo()->newFile($title);
 *
 * The convenience functions wfLocalFile() and wfFindFile() should be sufficient
 * in most cases.
 *
 * @addtogroup FileRepo
 */
class File {
        const DELETED_FILE = 1;
        const DELETED_COMMENT = 2;
        const DELETED_USER = 4;
        const DELETED_RESTRICTED = 8;
        const RENDER_NOW = 1;

        const DELETE_SOURCE = 1;

        /** 
         * Some member variables can be lazy-initialised using __get(). The 
         * initialisation function for these variables is always a function named
         * like getVar(), where Var is the variable name with upper-case first 
         * letter.
         *
         * The following variables are initialised in this way in this base class:
         *    name, extension, handler, path, canRender, isSafeFile, 
         *    transformScript, hashPath, pageCount, url
         *
         * Code within this class should generally use the accessor function 
         * directly, since __get() isn't re-entrant and therefore causes bugs that
         * depend on initialisation order.
         */

        /**
         * The following member variables are not lazy-initialised
         */
        var $repo, $title, $lastError;

        /**
         * Call this constructor from child classes
         */
        function __construct( $title, $repo ) {
                $this->title = $title;
                $this->repo = $repo;
        }

        function __get( $name ) {
                $function = array( $this, 'get' . ucfirst( $name ) );
                if ( !is_callable( $function ) ) {
                        return null;
                } else {
                        $this->$name = call_user_func( $function );
                        return $this->$name;
                }
        }

        /**
         * Normalize a file extension to the common form, and ensure it's clean.
         * Extensions with non-alphanumeric characters will be discarded.
         *
         * @param $ext string (without the .)
         * @return string
         */
        static function normalizeExtension( $ext ) {
                $lower = strtolower( $ext );
                $squish = array(
                        'htm' => 'html',
                        'jpeg' => 'jpg',
                        'mpeg' => 'mpg',
                        'tiff' => 'tif' );
                if( isset( $squish[$lower] ) ) {
                        return $squish[$lower];
                } elseif( preg_match( '/^[0-9a-z]+$/', $lower ) ) {
                        return $lower;
                } else {
                        return '';
                }
        }

        /**
         * Upgrade the database row if there is one
         * Called by ImagePage
         * STUB
         */
        function upgradeRow() {}

        /**
         * Split an internet media type into its two components; if not
         * a two-part name, set the minor type to 'unknown'.
         *
         * @param $mime "text/html" etc
         * @return array ("text", "html") etc
         */
        static function splitMime( $mime ) {
                if( strpos( $mime, '/' ) !== false ) {
                        return explode( '/', $mime, 2 );
                } else {
                        return array( $mime, 'unknown' );
                }
        }
        
        /**
         * Return the name of this file
         * @public
         */
        function getName() {
                if ( !isset( $this->name ) ) {
                        $this->name = $this->repo->getNameFromTitle( $this->title );
                }
                return $this->name; 
        }

        /**
         * Get the file extension, e.g. "svg"
         */
        function getExtension() {
                if ( !isset( $this->extension ) ) {
                        $n = strrpos( $this->getName(), '.' );
                        $this->extension = self::normalizeExtension( 
                                $n ? substr( $this->getName(), $n + 1 ) : '' );
                }
                return $this->extension;
        }

        /**
         * Return the associated title object
         * @public
         */
        function getTitle() { return $this->title; }

        /**
         * Return the URL of the file
         * @public
         */
        function getUrl() { 
                if ( !isset( $this->url ) ) {
                        $this->url = $this->repo->getZoneUrl( 'public' ) . '/' . $this->getUrlRel();
                }
                return $this->url; 
        }

        function getViewURL() {
                if( $this->mustRender()) {
                        if( $this->canRender() ) {
                                return $this->createThumb( $this->getWidth() );
                        }
                        else {
                                wfDebug(__METHOD__.': supposed to render '.$this->getName().' ('.$this->getMimeType()."), but can't!\n");
                                return $this->getURL(); #hm... return NULL?
                        }
                } else {
                        return $this->getURL();
                }
        }

        /**
        * Return the full filesystem path to the file. Note that this does
        * not mean that a file actually exists under that location.
        *
        * This path depends on whether directory hashing is active or not,
        * i.e. whether the files are all found in the same directory,
        * or in hashed paths like /images/3/3c.
        *
        * May return false if the file is not locally accessible.
        *
        * @public
        */
        function getPath() {
                if ( !isset( $this->path ) ) {
                        $this->path = $this->repo->getZonePath('public') . '/' . $this->getRel();
                }
                return $this->path;
        }

        /**
        * Alias for getPath()
        * @public
        */
        function getFullPath() {
                return $this->getPath();
        }

        /**
         * Return the width of the image. Returns false if the width is unknown 
         * or undefined.
         *
         * STUB
         * Overridden by LocalFile, UnregisteredLocalFile
         * @public
         */
        function getWidth( $page = 1 ) { return false; }

        /**
         * Return the height of the image. Returns false if the height is unknown 
         * or undefined
         *
         * STUB
         * Overridden by LocalFile, UnregisteredLocalFile
         * @public
         */
        function getHeight( $page = 1 ) { return false; }

        /**
         * Get handler-specific metadata
         * Overridden by LocalFile, UnregisteredLocalFile
         * STUB
         */
        function getMetadata() { return false; }

        /**
         * Return the size of the image file, in bytes
         * Overridden by LocalFile, UnregisteredLocalFile
         * STUB
         * @public
         */
        function getSize() { return false; }

        /**
         * Returns the mime type of the file.
         * Overridden by LocalFile, UnregisteredLocalFile
         * STUB
         */
        function getMimeType() { return 'unknown/unknown'; }

        /**
         * Return the type of the media in the file.
         * Use the value returned by this function with the MEDIATYPE_xxx constants.
         * Overridden by LocalFile,
         * STUB
         */
        function getMediaType() { return MEDIATYPE_UNKNOWN; }

        /**
         * Checks if the file can be presented to the browser as a bitmap.
         *
         * Currently, this checks if the file is an image format
         * that can be converted to a format
         * supported by all browsers (namely GIF, PNG and JPEG),
         * or if it is an SVG image and SVG conversion is enabled.
         */
        function canRender() {
                if ( !isset( $this->canRender ) ) {
                        $this->canRender = $this->getHandler() && $this->handler->canRender();
                }
                return $this->canRender;
        }

        /**
         * Accessor for __get()
         */
        protected function getCanRender() {
                return $this->canRender();
        }

        /**
         * Return true if the file is of a type that can't be directly
         * rendered by typical browsers and needs to be re-rasterized.
         *
         * This returns true for everything but the bitmap types
         * supported by all browsers, i.e. JPEG; GIF and PNG. It will
         * also return true for any non-image formats.
         *
         * @return bool
         */
        function mustRender() {
                return $this->getHandler() && $this->handler->mustRender();
        }

        /**
         * Determines if this media file may be shown inline on a page.
         *
         * This is currently synonymous to canRender(), but this could be
         * extended to also allow inline display of other media,
         * like flash animations or videos. If you do so, please keep in mind that
         * that could be a security risk.
         */
        function allowInlineDisplay() {
                return $this->canRender();
        }

        /**
         * Determines if this media file is in a format that is unlikely to
         * contain viruses or malicious content. It uses the global
         * $wgTrustedMediaFormats list to determine if the file is safe.
         *
         * This is used to show a warning on the description page of non-safe files.
         * It may also be used to disallow direct [[media:...]] links to such files.
         *
         * Note that this function will always return true if allowInlineDisplay()
         * or isTrustedFile() is true for this file.
         */
        function isSafeFile() {
                if ( !isset( $this->isSafeFile ) ) {
                        $this->isSafeFile = $this->_getIsSafeFile();
                }
                return $this->isSafeFile;
        }
        
        /** Accessor for __get() */
        protected function getIsSafeFile() {
                return $this->isSafeFile();
        }

        /** Uncached accessor */
        protected function _getIsSafeFile() {
                if ($this->allowInlineDisplay()) return true;
                if ($this->isTrustedFile()) return true;

                global $wgTrustedMediaFormats;

                $type= $this->getMediaType();
                $mime= $this->getMimeType();
                #wfDebug("LocalFile::isSafeFile: type= $type, mime= $mime\n");

                if (!$type || $type===MEDIATYPE_UNKNOWN) return false; #unknown type, not trusted
                if ( in_array( $type, $wgTrustedMediaFormats) ) return true;

                if ($mime==="unknown/unknown") return false; #unknown type, not trusted
                if ( in_array( $mime, $wgTrustedMediaFormats) ) return true;

                return false;
        }

        /** Returns true if the file is flagged as trusted. Files flagged that way
        * can be linked to directly, even if that is not allowed for this type of
        * file normally.
        *
        * This is a dummy function right now and always returns false. It could be
        * implemented to extract a flag from the database. The trusted flag could be
        * set on upload, if the user has sufficient privileges, to bypass script-
        * and html-filters. It may even be coupled with cryptographics signatures
        * or such.
        */
        function isTrustedFile() {
                #this could be implemented to check a flag in the databas,
                #look for signatures, etc
                return false;
        }

        /**
         * Returns true if file exists in the repository.
         *
         * Overridden by LocalFile to avoid unnecessary stat calls.
         * 
         * @return boolean Whether file exists in the repository.
         * @public
         */
        function exists() {
                return $this->getPath() && file_exists( $this->path );
        }

        function getTransformScript() {
                if ( !isset( $this->transformScript ) ) {
                        $this->transformScript = false;
                        if ( $this->repo ) {
                                $script = $this->repo->getThumbScriptUrl();
                                if ( $script ) {
                                        $this->transformScript = "$script?f=" . urlencode( $this->getName() );
                                }
                        }
                }
                return $this->transformScript;
        }

        /**
         * Get a ThumbnailImage which is the same size as the source
         */
        function getUnscaledThumb( $page = false ) {
                $width = $this->getWidth( $page );
                if ( !$width ) {
                        return $this->iconThumb();
                }
                if ( $page ) {
                        $params = array(
                                'page' => $page,
                                'width' => $this->getWidth( $page )
                        );
                } else {
                        $params = array( 'width' => $this->getWidth() );
                }
                return $this->transform( $params );
        }

        /**
         * Return the file name of a thumbnail with the specified parameters
         *
         * @param array $params Handler-specific parameters
         * @private
         */
        function thumbName( $params ) {
                if ( !$this->getHandler() ) {
                        return null;
                }
                $extension = $this->getExtension();
                list( $thumbExt, $thumbMime ) = $this->handler->getThumbType( $extension, $this->getMimeType() );
                $thumbName = $this->handler->makeParamString( $params ) . '-' . $this->getName();
                if ( $thumbExt != $extension ) {
                        $thumbName .= ".$thumbExt";
                }
                return $thumbName;
        }

        /**
         * Create a thumbnail of the image having the specified width/height.
         * The thumbnail will not be created if the width is larger than the
         * image's width. Let the browser do the scaling in this case.
         * The thumbnail is stored on disk and is only computed if the thumbnail
         * file does not exist OR if it is older than the image.
         * Returns the URL.
         *
         * Keeps aspect ratio of original image. If both width and height are
         * specified, the generated image will be no bigger than width x height,
         * and will also have correct aspect ratio.
         *
         * @param integer $width        maximum width of the generated thumbnail
         * @param integer $height       maximum height of the image (optional)
         * @public
         */
        function createThumb( $width, $height = -1 ) {
                $params = array( 'width' => $width );
                if ( $height != -1 ) {
                        $params['height'] = $height;
                }
                $thumb = $this->transform( $params );
                if( is_null( $thumb ) || $thumb->isError() ) return '';
                return $thumb->getUrl();
        }

        /**
         * As createThumb, but returns a ThumbnailImage object. This can
         * provide access to the actual file, the real size of the thumb,
         * and can produce a convenient <img> tag for you.
         *
         * For non-image formats, this may return a filetype-specific icon.
         *
         * @param integer $width        maximum width of the generated thumbnail
         * @param integer $height       maximum height of the image (optional)
         * @param boolean $render       True to render the thumbnail if it doesn't exist,
         *                              false to just return the URL
         *
         * @return ThumbnailImage or null on failure
         * @public
         *
         * @deprecated use transform()
         */
        function getThumbnail( $width, $height=-1, $render = true ) {
                $params = array( 'width' => $width );
                if ( $height != -1 ) {
                        $params['height'] = $height;
                }
                $flags = $render ? self::RENDER_NOW : 0;
                return $this->transform( $params, $flags );
        }

        /**
         * Transform a media file
         *
         * @param array $params An associative array of handler-specific parameters. Typical 
         *                      keys are width, height and page.
         * @param integer $flags A bitfield, may contain self::RENDER_NOW to force rendering
         * @return MediaTransformOutput
         */
        function transform( $params, $flags = 0 ) {
                global $wgUseSquid, $wgIgnoreImageErrors;

                wfProfileIn( __METHOD__ );
                do {
                        if ( !$this->getHandler() || !$this->handler->canRender() ) {
                                // not a bitmap or renderable image, don't try.
                                $thumb = $this->iconThumb();
                                break;
                        }

                        $script = $this->getTransformScript();
                        if ( $script && !($flags & self::RENDER_NOW) ) {
                                // Use a script to transform on client request
                                $thumb = $this->handler->getScriptedTransform( $this, $script, $params );
                                break;
                        }

                        $normalisedParams = $params;
                        $this->handler->normaliseParams( $this, $normalisedParams );
                        $thumbName = $this->thumbName( $normalisedParams );     
                        $thumbPath = $this->getThumbPath( $thumbName );
                        $thumbUrl = $this->getThumbUrl( $thumbName );

                        if ( $this->repo->canTransformVia404() && !($flags & self::RENDER_NOW ) ) {
                                $thumb = $this->handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                                break;
                        }

                        wfDebug( "Doing stat for $thumbPath\n" );
                        $this->migrateThumbFile( $thumbName );
                        if ( file_exists( $thumbPath ) ) {
                                $thumb = $this->handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                                break;
                        }
                        $thumb = $this->handler->doTransform( $this, $thumbPath, $thumbUrl, $params );

                        // Ignore errors if requested
                        if ( !$thumb ) {
                                $thumb = null;
                        } elseif ( $thumb->isError() ) {
                                $this->lastError = $thumb->toText();
                                if ( $wgIgnoreImageErrors && !($flags & self::RENDER_NOW) ) {
                                        $thumb = $this->handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                                }
                        }
                        
                        if ( $wgUseSquid ) {
                                wfPurgeSquidServers( array( $thumbUrl ) );
                        }
                } while (false);

                wfProfileOut( __METHOD__ );
                return $thumb;
        }

        /** 
         * Hook into transform() to allow migration of thumbnail files
         * STUB
         * Overridden by LocalFile
         */
        function migrateThumbFile() {}

        /**
         * Get a MediaHandler instance for this file
         */
        function getHandler() { 
                if ( !isset( $this->handler ) ) {
                        $this->handler = MediaHandler::getHandler( $this->getMimeType() );
                }
                return $this->handler;
        }

        /**
         * Get a ThumbnailImage representing a file type icon
         * @return ThumbnailImage
         */
        function iconThumb() {
                global $wgStylePath, $wgStyleDirectory;

                $try = array( 'fileicon-' . $this->getExtension() . '.png', 'fileicon.png' );
                foreach( $try as $icon ) {
                        $path = '/common/images/icons/' . $icon;
                        $filepath = $wgStyleDirectory . $path;
                        if( file_exists( $filepath ) ) {
                                return new ThumbnailImage( $wgStylePath . $path, 120, 120 );
                        }
                }
                return null;
        }

        /**
         * Get last thumbnailing error.
         * Largely obsolete.
         */
        function getLastError() {
                return $this->lastError;
        }

        /**
         * Get all thumbnail names previously generated for this file
         * STUB
         * Overridden by LocalFile
         */
        function getThumbnails() { return array(); }

        /**
         * Purge shared caches such as thumbnails and DB data caching
         * STUB
         * Overridden by LocalFile
         */
        function purgeCache( $archiveFiles = array() ) {}

        /**
         * Purge the file description page, but don't go after
         * pages using the file. Use when modifying file history
         * but not the current data.
         */
        function purgeDescription() {
                $title = $this->getTitle();
                if ( $title ) {
                        $title->invalidateCache();
                        $title->purgeSquid();
                }
        }
        
        /**
         * Purge metadata and all affected pages when the file is created,
         * deleted, or majorly updated. A set of additional URLs may be
         * passed to purge, such as specific file files which have changed.
         * @param $urlArray array
         */
        function purgeEverything( $urlArr=array() ) {
                // Delete thumbnails and refresh file metadata cache
                $this->purgeCache();
                $this->purgeDescription();

                // Purge cache of all pages using this file
                $title = $this->getTitle();
                if ( $title ) {
                        $update = new HTMLCacheUpdate( $title, 'imagelinks' );
                        $update->doUpdate();
                }
        }

        /**
         * Return the history of this file, line by line. Starts with current version, 
         * then old versions. Should return an object similar to an image/oldimage 
         * database row.
         *
         * @public
         * STUB
         * Overridden in LocalFile
         */
        function nextHistoryLine() {
                return false;
        }

        /**
         * Reset the history pointer to the first element of the history
         * @public
         * STUB
         * Overridden in LocalFile.
         */
        function resetHistory() {}

        /**
         * Get the filename hash component of the directory including trailing slash,
         * e.g. f/fa/
         * If the repository is not hashed, returns an empty string.
         */
        function getHashPath() {
                if ( !isset( $this->hashPath ) ) {
                        $this->hashPath = $this->repo->getHashPath( $this->getName() );
                }
                return $this->hashPath;
        }

        /**
         * Get the path of the file relative to the public zone root
         */
        function getRel() {
                return $this->getHashPath() . $this->getName();
        }

        /**
         * Get urlencoded relative path of the file
         */
        function getUrlRel() {
                return $this->getHashPath() . urlencode( $this->getName() );
        }

        /** Get the path of the archive directory, or a particular file if $suffix is specified */
        function getArchivePath( $suffix = false ) {
                $path = $this->repo->getZonePath('public') . '/archive/' . $this->getHashPath();
                if ( $suffix !== false ) {
                        $path .= '/' . $suffix;
                }
                return $path;
        }

        /** Get the path of the thumbnail directory, or a particular file if $suffix is specified */
        function getThumbPath( $suffix = false ) {
                $path = $this->repo->getZonePath('public') . '/thumb/' . $this->getRel();
                if ( $suffix !== false ) {
                        $path .= '/' . $suffix;
                }
                return $path;
        }

        /** Get the URL of the archive directory, or a particular file if $suffix is specified */
        function getArchiveUrl( $suffix = false ) {
                $path = $this->repo->getZoneUrl('public') . '/archive/' . $this->getHashPath();
                if ( $suffix !== false ) {
                        $path .= '/' . urlencode( $suffix );
                }
                return $path;
        }

        /** Get the URL of the thumbnail directory, or a particular file if $suffix is specified */
        function getThumbUrl( $suffix = false ) {
                $path = $this->repo->getZoneUrl('public') . '/thumb/' . $this->getUrlRel();
                if ( $suffix !== false ) {
                        $path .= '/' . urlencode( $suffix );
                }
                return $path;
        }

        /** Get the virtual URL for an archive file or directory */
        function getArchiveVirtualUrl( $suffix = false ) {
                $path = $this->repo->getVirtualUrl() . '/public/archive/' . $this->getHashPath();
                if ( $suffix !== false ) {
                        $path .= '/' . urlencode( $suffix );
                }
                return $path;
        }

        /** Get the virtual URL for a thumbnail file or directory */
        function getThumbVirtualUrl( $suffix = false ) {
                $path = $this->repo->getVirtualUrl() . '/public/thumb/' . $this->getHashPath();
                if ( $suffix !== false ) {
                        $path .= '/' . urlencode( $suffix );
                }
                return $path;
        }

        /**
         * @return bool
         */
        function isHashed() {
                return $this->repo->isHashed();
        }

        function readOnlyError() {
                throw new MWException( get_class($this) . ': write operations are not supported' );
        }

        /**
         * Record a file upload in the upload log and the image table
         * STUB
         * Overridden by LocalFile
         */
        function recordUpload( $oldver, $desc, $license = '', $copyStatus = '', $source = '', $watch = false ) { 
                $this->readOnlyError(); 
        }

        /**
         * Move or copy a file to its public location. If a file exists at the  
         * destination, move it to an archive. Returns the archive name on success 
         * or an empty string if it was a new file, and a wikitext-formatted 
         * WikiError object on failure. 
         *
         * The archive name should be passed through to recordUpload for database
         * registration.
         *
         * @param string $sourcePath Local filesystem path to the source image
         * @param integer $flags A bitwise combination of:
         *     File::DELETE_SOURCE    Delete the source file, i.e. move 
         *         rather than copy
         * @return The archive name on success or an empty string if it was a new 
         *     file, and a wikitext-formatted WikiError object on failure. 
         *
         * STUB
         * Overridden by LocalFile
         */
        function publish( $srcPath, $flags = 0 ) {
                $this->readOnlyError();
        }

        /**
         * Get an array of Title objects which are articles which use this file
         * Also adds their IDs to the link cache
         *
         * This is mostly copied from Title::getLinksTo()
         *
         * @deprecated Use HTMLCacheUpdate, this function uses too much memory
         */
        function getLinksTo( $options = '' ) {
                wfProfileIn( __METHOD__ );

                // Note: use local DB not repo DB, we want to know local links
                if ( $options ) {
                        $db = wfGetDB( DB_MASTER );
                } else {
                        $db = wfGetDB( DB_SLAVE );
                }
                $linkCache =& LinkCache::singleton();

                list( $page, $imagelinks ) = $db->tableNamesN( 'page', 'imagelinks' );
                $encName = $db->addQuotes( $this->getName() );
                $sql = "SELECT page_namespace,page_title,page_id FROM $page,$imagelinks WHERE page_id=il_from AND il_to=$encName $options";
                $res = $db->query( $sql, __METHOD__ );

                $retVal = array();
                if ( $db->numRows( $res ) ) {
                        while ( $row = $db->fetchObject( $res ) ) {
                                if ( $titleObj = Title::makeTitle( $row->page_namespace, $row->page_title ) ) {
                                        $linkCache->addGoodLinkObj( $row->page_id, $titleObj );
                                        $retVal[] = $titleObj;
                                }
                        }
                }
                $db->freeResult( $res );
                wfProfileOut( __METHOD__ );
                return $retVal;
        }

        function getExifData() {
                if ( !$this->getHandler() || $this->handler->getMetadataType( $this ) != 'exif' ) {
                        return array();
                }
                $metadata = $this->getMetadata();
                if ( !$metadata ) {
                        return array();
                }
                $exif = unserialize( $metadata );
                if ( !$exif ) {
                        return array();
                }
                unset( $exif['MEDIAWIKI_EXIF_VERSION'] );
                $format = new FormatExif( $exif );

                return $format->getFormattedData();
        }

        /**
         * Returns true if the file comes from the local file repository.
         *
         * @return bool
         */
        function isLocal() { 
                return $this->repo && $this->repo->getName() == 'local'; 
        }

        /**
         * Returns true if the image is an old version
         * STUB
         */
        function isOld() {
                return false;
        }

        /**
         * Is this file a "deleted" file in a private archive?
         * STUB
         */
        function isDeleted( $field ) {
                return false;
        }

        /**
         * Was this file ever deleted from the wiki?
         *
         * @return bool
         */
        function wasDeleted() {
                $title = $this->getTitle();
                return $title && $title->isDeleted() > 0;
        }

        /**
         * Delete all versions of the file.
         *
         * Moves the files into an archive directory (or deletes them)
         * and removes the database rows.
         *
         * Cache purging is done; logging is caller's responsibility.
         *
         * @param $reason
         * @return true on success, false on some kind of failure
         * STUB
         * Overridden by LocalFile
         */
        function delete( $reason, $suppress=false ) {
                $this->readOnlyError();
        }

        /**
         * Restore all or specified deleted revisions to the given file.
         * Permissions and logging are left to the caller.
         *
         * May throw database exceptions on error.
         *
         * @param $versions set of record ids of deleted items to restore,
         *                    or empty to restore all revisions.
         * @return the number of file revisions restored if successful,
         *         or false on failure
         * STUB
         * Overridden by LocalFile
         */
        function restore( $versions=array(), $Unsuppress=false ) {
                $this->readOnlyError();
        }

        /**
         * Returns 'true' if this image is a multipage document, e.g. a DJVU
         * document.
         *
         * @return Bool
         */
        function isMultipage() {
                return $this->getHandler() && $this->handler->isMultiPage();
        }

        /**
         * Returns the number of pages of a multipage document, or NULL for
         * documents which aren't multipage documents
         */
        function pageCount() {
                if ( !isset( $this->pageCount ) ) {
                        if ( $this->getHandler() && $this->handler->isMultiPage() ) {
                                $this->pageCount = $this->handler->pageCount( $this );
                        } else {
                                $this->pageCount = false;
                        }
                }
                return $this->pageCount;
        }

        /**
         * Calculate the height of a thumbnail using the source and destination width
         */
        static function scaleHeight( $srcWidth, $srcHeight, $dstWidth ) {
                // Exact integer multiply followed by division
                if ( $srcWidth == 0 ) {
                        return 0;
                } else {
                        return round( $srcHeight * $dstWidth / $srcWidth );
                }
        }
        
        /**
         * Get an image size array like that returned by getimagesize(), or false if it 
         * can't be determined.
         *
         * @param string $fileName The filename
         * @return array
         */
        function getImageSize( $fileName ) {
                if ( !$this->getHandler() ) {
                        return false;
                }
                return $this->handler->getImageSize( $this, $fileName );
        }

        /**
         * Get the URL of the image description page. May return false if it is
         * unknown or not applicable.
         */
        function getDescriptionUrl() {
                return $this->repo->getDescriptionUrl( $this->getName() );
        }

        /**
         * Get the HTML text of the description page, if available
         */
        function getDescriptionText() {
                if ( !$this->repo->fetchDescription ) {
                        return false;
                }
                $renderUrl = $this->repo->getDescriptionRenderUrl( $this->getName() );
                if ( $renderUrl ) {
                        wfDebug( "Fetching shared description from $renderUrl\n" );
                        return Http::get( $renderUrl );
                } else {
                        return false;
                }
        }

        /**
         * Get the 14-character timestamp of the file upload, or false if 
         */
        function getTimestmap() {
                $path = $this->getPath();
                if ( !file_exists( $path ) ) {
                        return false;
                }
                return wfTimestamp( filemtime( $path ) );
        }
        
        /**
         * Determine if the current user is allowed to view a particular
         * field of this file, if it's marked as deleted.
         * STUB
         * @param int $field                                    
         * @return bool
         */
        function userCan( $field ) {
                return true;
        }
}

?>