Remove silly 'm' prefix from StubObject/DeprecatedGlobal members

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

<?php
/**
 * @defgroup FileAbstraction File abstraction
 * @ingroup FileRepo
 *
 * Represents files in a repository.
 */

/**
 * Base code for 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
 * @ingroup FileAbstraction
 */

/**
 * 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.
 *
 * @ingroup FileAbstraction
 */
abstract class File {
        // Bitfield values akin to the Revision deletion constants
        const DELETED_FILE = 1;
        const DELETED_COMMENT = 2;
        const DELETED_USER = 4;
        const DELETED_RESTRICTED = 8;

        /** Force rendering in the current process */
        const RENDER_NOW = 1;
        /**
         * Force rendering even if thumbnail already exist and using RENDER_NOW
         * I.e. you have to pass both flags: File::RENDER_NOW | File::RENDER_FORCE
         */
        const RENDER_FORCE = 2;

        const DELETE_SOURCE = 1;

        // Audience options for File::getDescription()
        const FOR_PUBLIC = 1;
        const FOR_THIS_USER = 2;
        const RAW = 3;

        // Options for File::thumbName()
        const THUMB_FULL_NAME = 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 FileRepo|LocalRepo|ForeignAPIRepo|bool */
        public $repo;

        /** @var Title|string|bool */
        protected $title;

        /** @var string Text of last error */
        protected $lastError;

        /** @var string Main part of the title, with underscores (Title::getDBkey) */
        protected $redirected;

        /** @var Title */
        protected $redirectedTitle;

        /** @var FSFile|bool False if undefined */
        protected $fsFile;

        /** @var MediaHandler */
        protected $handler;

        /** @var string The URL corresponding to one of the four basic zones */
        protected $url;

        /** @var string File extension */
        protected $extension;

        /** @var string The name of a file from its title object */
        protected $name;

        /** @var string The storage path corresponding to one of the zones */
        protected $path;

        /** @var string Relative path including trailing slash */
        protected $hashPath;

        /** @var string number of pages of a multipage document, or false for
         *    documents which aren't multipage documents
         */
        protected $pageCount;

        /** @var string URL of transformscript (for example thumb.php) */
        protected $transformScript;

        /** @var Title */
        protected $redirectTitle;

        /** @var bool Wether the output of transform() for this file is likely to be valid. */
        protected $canRender;

        /** @var bool Wether this media file is in a format that is unlikely to
         *    contain viruses or malicious content
         */
        protected $isSafeFile;

        /** @var string Required Repository class type */
        protected $repoClass = 'FileRepo';

        /**
         * Call this constructor from child classes.
         *
         * Both $title and $repo are optional, though some functions
         * may return false or throw exceptions if they are not set.
         * Most subclasses will want to call assertRepoDefined() here.
         *
         * @param Title|string|bool $title
         * @param FileRepo|bool $repo
         */
        function __construct( $title, $repo ) {
                if ( $title !== false ) { // subclasses may not use MW titles
                        $title = self::normalizeTitle( $title, 'exception' );
                }
                $this->title = $title;
                $this->repo = $repo;
        }

        /**
         * Given a string or Title object return either a
         * valid Title object with namespace NS_FILE or null
         *
         * @param Title|string $title
         * @param string|bool $exception Use 'exception' to throw an error on bad titles
         * @throws MWException
         * @return Title|null
         */
        static function normalizeTitle( $title, $exception = false ) {
                $ret = $title;
                if ( $ret instanceof Title ) {
                        # Normalize NS_MEDIA -> NS_FILE
                        if ( $ret->getNamespace() == NS_MEDIA ) {
                                $ret = Title::makeTitleSafe( NS_FILE, $ret->getDBkey() );
                        # Sanity check the title namespace
                        } elseif ( $ret->getNamespace() !== NS_FILE ) {
                                $ret = null;
                        }
                } else {
                        # Convert strings to Title objects
                        $ret = Title::makeTitleSafe( NS_FILE, (string)$ret );
                }
                if ( !$ret && $exception !== false ) {
                        throw new MWException( "`$title` is not a valid file title." );
                }

                return $ret;
        }

        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 string $ext (without the .)
         * @return string
         */
        static function normalizeExtension( $ext ) {
                $lower = strtolower( $ext );
                $squish = array(
                        'htm' => 'html',
                        'jpeg' => 'jpg',
                        'mpeg' => 'mpg',
                        'tiff' => 'tif',
                        'ogv' => 'ogg' );
                if ( isset( $squish[$lower] ) ) {
                        return $squish[$lower];
                } elseif ( preg_match( '/^[0-9a-z]+$/', $lower ) ) {
                        return $lower;
                } else {
                        return '';
                }
        }

        /**
         * Checks if file extensions are compatible
         *
         * @param File $old Old file
         * @param string $new New name
         *
         * @return bool|null
         */
        static function checkExtensionCompatibility( File $old, $new ) {
                $oldMime = $old->getMimeType();
                $n = strrpos( $new, '.' );
                $newExt = self::normalizeExtension( $n ? substr( $new, $n + 1 ) : '' );
                $mimeMagic = MimeMagic::singleton();

                return $mimeMagic->isMatchingExtension( $newExt, $oldMime );
        }

        /**
         * 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 string $mime "text/html" etc
         * @return array ("text", "html") etc
         */
        public static function splitMime( $mime ) {
                if ( strpos( $mime, '/' ) !== false ) {
                        return explode( '/', $mime, 2 );
                } else {
                        return array( $mime, 'unknown' );
                }
        }

        /**
         * Callback for usort() to do file sorts by name
         *
         * @param File $a
         * @param File $b
         * @return int Result of name comparison
         */
        public static function compare( File $a, File $b ) {
                return strcmp( $a->getName(), $b->getName() );
        }

        /**
         * Return the name of this file
         *
         * @return string
         */
        public function getName() {
                if ( !isset( $this->name ) ) {
                        $this->assertRepoDefined();
                        $this->name = $this->repo->getNameFromTitle( $this->title );
                }

                return $this->name;
        }

        /**
         * Get the file extension, e.g. "svg"
         *
         * @return string
         */
        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
         *
         * @return Title
         */
        public function getTitle() {
                return $this->title;
        }

        /**
         * Return the title used to find this file
         *
         * @return Title
         */
        public function getOriginalTitle() {
                if ( $this->redirected ) {
                        return $this->getRedirectedTitle();
                }

                return $this->title;
        }

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

                return $this->url;
        }

        /**
         * Return a fully-qualified URL to the file.
         * Upload URL paths _may or may not_ be fully qualified, so
         * we check. Local paths are assumed to belong on $wgServer.
         *
         * @return string
         */
        public function getFullUrl() {
                return wfExpandUrl( $this->getUrl(), PROTO_RELATIVE );
        }

        /**
         * @return string
         */
        public function getCanonicalUrl() {
                return wfExpandUrl( $this->getUrl(), PROTO_CANONICAL );
        }

        /**
         * @return string
         */
        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 storage 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.
         *
         * Most callers don't check the return value, but ForeignAPIFile::getPath
         * returns false.
         *
         * @return string|bool ForeignAPIFile::getPath can return false
         */
        public function getPath() {
                if ( !isset( $this->path ) ) {
                        $this->assertRepoDefined();
                        $this->path = $this->repo->getZonePath( 'public' ) . '/' . $this->getRel();
                }

                return $this->path;
        }

        /**
         * Get an FS copy or original of this file and return the path.
         * Returns false on failure. Callers must not alter the file.
         * Temporary files are cleared automatically.
         *
         * @return string|bool False on failure
         */
        public function getLocalRefPath() {
                $this->assertRepoDefined();
                if ( !isset( $this->fsFile ) ) {
                        $this->fsFile = $this->repo->getLocalReference( $this->getPath() );
                        if ( !$this->fsFile ) {
                                $this->fsFile = false; // null => false; cache negative hits
                        }
                }

                return ( $this->fsFile )
                        ? $this->fsFile->getPath()
                        : false;
        }

        /**
         * Return the width of the image. Returns false if the width is unknown
         * or undefined.
         *
         * STUB
         * Overridden by LocalFile, UnregisteredLocalFile
         *
         * @param int $page
         * @return int|bool
         */
        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
         *
         * @param int $page
         * @return bool|int False on failure
         */
        public function getHeight( $page = 1 ) {
                return false;
        }

        /**
         * Returns ID or name of user who uploaded the file
         * STUB
         *
         * @param string $type 'text' or 'id'
         * @return string|int
         */
        public function getUser( $type = 'text' ) {
                return null;
        }

        /**
         * Get the duration of a media file in seconds
         *
         * @return int
         */
        public function getLength() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getLength( $this );
                } else {
                        return 0;
                }
        }

        /**
         * Return true if the file is vectorized
         *
         * @return bool
         */
        public function isVectorized() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->isVectorized( $this );
                } else {
                        return false;
                }
        }

        /**
         * Gives a (possibly empty) list of languages to render
         * the file in.
         *
         * If the file doesn't have translations, or if the file
         * format does not support that sort of thing, returns
         * an empty array.
         *
         * @return array
         * @since 1.23
         */
        public function getAvailableLanguages() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getAvailableLanguages( $this );
                } else {
                        return array();
                }
        }

        /**
         * In files that support multiple language, what is the default language
         * to use if none specified.
         *
         * @return string Lang code, or null if filetype doesn't support multiple languages.
         * @since 1.23
         */
        public function getDefaultRenderLanguage() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getDefaultRenderLanguage( $this );
                } else {
                        return null;
                }
        }

        /**
         * Will the thumbnail be animated if one would expect it to be.
         *
         * Currently used to add a warning to the image description page
         *
         * @return bool false if the main image is both animated
         *   and the thumbnail is not. In all other cases must return
         *   true. If image is not renderable whatsoever, should
         *   return true.
         */
        public function canAnimateThumbIfAppropriate() {
                $handler = $this->getHandler();
                if ( !$handler ) {
                        // We cannot handle image whatsoever, thus
                        // one would not expect it to be animated
                        // so true.
                        return true;
                } else {
                        if ( $this->allowInlineDisplay()
                                && $handler->isAnimatedImage( $this )
                                && !$handler->canAnimateThumbnail( $this )
                        ) {
                                // Image is animated, but thumbnail isn't.
                                // This is unexpected to the user.
                                return false;
                        } else {
                                // Image is not animated, so one would
                                // not expect thumb to be
                                return true;
                        }
                }
        }

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

        /**
         * Like getMetadata but returns a handler independent array of common values.
         * @see MediaHandler::getCommonMetaArray()
         * @return array|bool Array or false if not supported
         * @since 1.23
         */
        public function getCommonMetaArray() {
                $handler = $this->getHandler();

                if ( !$handler ) {
                        return false;
                }

                return $handler->getCommonMetaArray( $this );
        }

        /**
         * get versioned metadata
         *
         * @param array|string $metadata Array or string of (serialized) metadata
         * @param int $version Version number.
         * @return array Array containing metadata, or what was passed to it on fail
         *   (unserializing if not array)
         */
        public function convertMetadataVersion( $metadata, $version ) {
                $handler = $this->getHandler();
                if ( !is_array( $metadata ) ) {
                        // Just to make the return type consistent
                        $metadata = unserialize( $metadata );
                }
                if ( $handler ) {
                        return $handler->convertMetadataVersion( $metadata, $version );
                } else {
                        return $metadata;
                }
        }

        /**
         * Return the bit depth of the file
         * Overridden by LocalFile
         * STUB
         * @return int
         */
        public function getBitDepth() {
                return 0;
        }

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

        /**
         * Returns the mime type of the file.
         * Overridden by LocalFile, UnregisteredLocalFile
         * STUB
         *
         * @return string
         */
        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
         * @return string
         */
        function getMediaType() {
                return MEDIATYPE_UNKNOWN;
        }

        /**
         * Checks if the output of transform() for this file is likely
         * to be valid. If this is false, various user elements will
         * display a placeholder instead.
         *
         * 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.
         *
         * @return bool
         */
        function canRender() {
                if ( !isset( $this->canRender ) ) {
                        $this->canRender = $this->getHandler() && $this->handler->canRender( $this );
                }

                return $this->canRender;
        }

        /**
         * Accessor for __get()
         * @return bool
         */
        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( $this );
        }

        /**
         * Alias for canRender()
         *
         * @return bool
         */
        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.
         *
         * @return bool
         */
        function isSafeFile() {
                if ( !isset( $this->isSafeFile ) ) {
                        $this->isSafeFile = $this->getIsSafeFileUncached();
                }

                return $this->isSafeFile;
        }

        /**
         * Accessor for __get()
         *
         * @return bool
         */
        protected function getIsSafeFile() {
                return $this->isSafeFile();
        }

        /**
         * Uncached accessor
         *
         * @return bool
         */
        protected function getIsSafeFileUncached() {
                global $wgTrustedMediaFormats;

                if ( $this->allowInlineDisplay() ) {
                        return true;
                }
                if ( $this->isTrustedFile() ) {
                        return true;
                }

                $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.
         *
         * @return bool
         */
        function isTrustedFile() {
                #this could be implemented to check a flag in the database,
                #look for signatures, etc
                return false;
        }

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

        /**
         * Returns true if file exists in the repository and can be included in a page.
         * It would be unsafe to include private images, making public thumbnails inadvertently
         *
         * @return bool Whether file exists in the repository and is includable.
         */
        public function isVisible() {
                return $this->exists();
        }

        /**
         * @return string
         */
        function getTransformScript() {
                if ( !isset( $this->transformScript ) ) {
                        $this->transformScript = false;
                        if ( $this->repo ) {
                                $script = $this->repo->getThumbScriptUrl();
                                if ( $script ) {
                                        $this->transformScript = wfAppendQuery( $script, array( 'f' => $this->getName() ) );
                                }
                        }
                }

                return $this->transformScript;
        }

        /**
         * Get a ThumbnailImage which is the same size as the source
         *
         * @param array $handlerParams
         *
         * @return string
         */
        function getUnscaledThumb( $handlerParams = array() ) {
                $hp =& $handlerParams;
                $page = isset( $hp['page'] ) ? $hp['page'] : false;
                $width = $this->getWidth( $page );
                if ( !$width ) {
                        return $this->iconThumb();
                }
                $hp['width'] = $width;
                // be sure to ignore any height specification as well (bug 62258)
                unset( $hp['height'] );

                return $this->transform( $hp );
        }

        /**
         * Return the file name of a thumbnail with the specified parameters.
         * Use File::THUMB_FULL_NAME to always get a name like "<params>-<source>".
         * Otherwise, the format may be "<params>-<source>" or "<params>-thumbnail.<ext>".
         *
         * @param array $params Handler-specific parameters
         * @param int $flags Bitfield that supports THUMB_* constants
         * @return string
         */
        public function thumbName( $params, $flags = 0 ) {
                $name = ( $this->repo && !( $flags & self::THUMB_FULL_NAME ) )
                        ? $this->repo->nameForThumb( $this->getName() )
                        : $this->getName();

                return $this->generateThumbName( $name, $params );
        }

        /**
         * Generate a thumbnail file name from a name and specified parameters
         *
         * @param string $name
         * @param array $params Parameters which will be passed to MediaHandler::makeParamString
         * @return string
         */
        public function generateThumbName( $name, $params ) {
                if ( !$this->getHandler() ) {
                        return null;
                }
                $extension = $this->getExtension();
                list( $thumbExt, ) = $this->handler->getThumbType(
                        $extension, $this->getMimeType(), $params );
                $thumbName = $this->handler->makeParamString( $params ) . '-' . $name;
                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 int $width Maximum width of the generated thumbnail
         * @param int $height Maximum height of the image (optional)
         *
         * @return string
         */
        public function createThumb( $width, $height = -1 ) {
                $params = array( 'width' => $width );
                if ( $height != -1 ) {
                        $params['height'] = $height;
                }
                $thumb = $this->transform( $params );
                if ( !$thumb || $thumb->isError() ) {
                        return '';
                }

                return $thumb->getUrl();
        }

        /**
         * Return either a MediaTransformError or placeholder thumbnail (if $wgIgnoreImageErrors)
         *
         * @param string $thumbPath Thumbnail storage path
         * @param string $thumbUrl Thumbnail URL
         * @param array $params
         * @param int $flags
         * @return MediaTransformOutput
         */
        protected function transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags ) {
                global $wgIgnoreImageErrors;

                $handler = $this->getHandler();
                if ( $handler && $wgIgnoreImageErrors && !( $flags & self::RENDER_NOW ) ) {
                        return $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                } else {
                        return new MediaTransformError( 'thumbnail_error',
                                $params['width'], 0, wfMessage( 'thumbnail-dest-create' )->text() );
                }
        }

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

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

                        // Get the descriptionUrl to embed it as comment into the thumbnail. Bug 19791.
                        $descriptionUrl = $this->getDescriptionUrl();
                        if ( $descriptionUrl ) {
                                $params['descriptionUrl'] = wfExpandUrl( $descriptionUrl, PROTO_CANONICAL );
                        }

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

                        $normalisedParams = $params;
                        $handler->normaliseParams( $this, $normalisedParams );

                        $thumbName = $this->thumbName( $normalisedParams );
                        $thumbUrl = $this->getThumbUrl( $thumbName );
                        $thumbPath = $this->getThumbPath( $thumbName ); // final thumb path

                        if ( $this->repo ) {
                                // Defer rendering if a 404 handler is set up...
                                if ( $this->repo->canTransformVia404() && !( $flags & self::RENDER_NOW ) ) {
                                        wfDebug( __METHOD__ . " transformation deferred.\n" );
                                        // XXX: Pass in the storage path even though we are not rendering anything
                                        // and the path is supposed to be an FS path. This is due to getScalerType()
                                        // getting called on the path and clobbering $thumb->getUrl() if it's false.
                                        $thumb = $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                                        break;
                                }
                                // Check if an up-to-date thumbnail already exists...
                                wfDebug( __METHOD__ . ": Doing stat for $thumbPath\n" );
                                if ( !( $flags & self::RENDER_FORCE ) && $this->repo->fileExists( $thumbPath ) ) {
                                        $timestamp = $this->repo->getFileTimestamp( $thumbPath );
                                        if ( $timestamp !== false && $timestamp >= $wgThumbnailEpoch ) {
                                                // XXX: Pass in the storage path even though we are not rendering anything
                                                // and the path is supposed to be an FS path. This is due to getScalerType()
                                                // getting called on the path and clobbering $thumb->getUrl() if it's false.
                                                $thumb = $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
                                                $thumb->setStoragePath( $thumbPath );
                                                break;
                                        }
                                } elseif ( $flags & self::RENDER_FORCE ) {
                                        wfDebug( __METHOD__ . " forcing rendering per flag File::RENDER_FORCE\n" );
                                }
                        }

                        // If the backend is ready-only, don't keep generating thumbnails
                        // only to return transformation errors, just return the error now.
                        if ( $this->repo->getReadOnlyReason() !== false ) {
                                $thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags );
                                break;
                        }

                        // Create a temp FS file with the same extension and the thumbnail
                        $thumbExt = FileBackend::extensionFromPath( $thumbPath );
                        $tmpFile = TempFSFile::factory( 'transform_', $thumbExt );
                        if ( !$tmpFile ) {
                                $thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags );
                                break;
                        }
                        $tmpThumbPath = $tmpFile->getPath(); // path of 0-byte temp file

                        // Actually render the thumbnail...
                        wfProfileIn( __METHOD__ . '-doTransform' );
                        $thumb = $handler->doTransform( $this, $tmpThumbPath, $thumbUrl, $params );
                        wfProfileOut( __METHOD__ . '-doTransform' );
                        $tmpFile->bind( $thumb ); // keep alive with $thumb

                        if ( !$thumb ) { // bad params?
                                $thumb = false;
                        } elseif ( $thumb->isError() ) { // transform error
                                $this->lastError = $thumb->toText();
                                // Ignore errors if requested
                                if ( $wgIgnoreImageErrors && !( $flags & self::RENDER_NOW ) ) {
                                        $thumb = $handler->getTransform( $this, $tmpThumbPath, $thumbUrl, $params );
                                }
                        } elseif ( $this->repo && $thumb->hasFile() && !$thumb->fileIsSource() ) {
                                // Copy the thumbnail from the file system into storage...
                                $disposition = $this->getThumbDisposition( $thumbName );
                                $status = $this->repo->quickImport( $tmpThumbPath, $thumbPath, $disposition );
                                if ( $status->isOK() ) {
                                        $thumb->setStoragePath( $thumbPath );
                                } else {
                                        $thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags );
                                }
                                // Give extensions a chance to do something with this thumbnail...
                                wfRunHooks( 'FileTransformed', array( $this, $thumb, $tmpThumbPath, $thumbPath ) );
                        }

                        // Purge. Useful in the event of Core -> Squid connection failure or squid
                        // purge collisions from elsewhere during failure. Don't keep triggering for
                        // "thumbs" which have the main image URL though (bug 13776)
                        if ( $wgUseSquid ) {
                                if ( !$thumb || $thumb->isError() || $thumb->getUrl() != $this->getURL() ) {
                                        SquidUpdate::purge( array( $thumbUrl ) );
                                }
                        }
                } while ( false );

                wfProfileOut( __METHOD__ );

                return is_object( $thumb ) ? $thumb : false;
        }

        /**
         * @param string $thumbName Thumbnail name
         * @param string $dispositionType Type of disposition (either "attachment" or "inline")
         * @return string Content-Disposition header value
         */
        function getThumbDisposition( $thumbName, $dispositionType = 'inline' ) {
                $fileName = $this->name; // file name to suggest
                $thumbExt = FileBackend::extensionFromPath( $thumbName );
                if ( $thumbExt != '' && $thumbExt !== $this->getExtension() ) {
                        $fileName .= ".$thumbExt";
                }

                return FileBackend::makeContentDisposition( $dispositionType, $fileName );
        }

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

        /**
         * Get a MediaHandler instance for this file
         *
         * @return MediaHandler|bool Registered MediaHandler for file's MIME type
         *   or false if none found
         */
        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 ) ) { // always FS
                                $params = array( 'width' => 120, 'height' => 120 );

                                return new ThumbnailImage( $this, $wgStylePath . $path, false, $params );
                        }
                }

                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
         * @return array
         */
        function getThumbnails() {
                return array();
        }

        /**
         * Purge shared caches such as thumbnails and DB data caching
         * STUB
         * Overridden by LocalFile
         * @param array $options Options, which include:
         *   'forThumbRefresh' : The purging is only to refresh thumbnails
         */
        function purgeCache( $options = 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.
         */
        function purgeEverything() {
                // 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 a fragment of the history of file.
         *
         * STUB
         * @param int $limit Limit of rows to return
         * @param string $start Only revisions older than $start will be returned
         * @param string $end Only revisions newer than $end will be returned
         * @param bool $inc Include the endpoints of the time range
         *
         * @return array
         */
        function getHistory( $limit = null, $start = null, $end = null, $inc = true ) {
                return array();
        }

        /**
         * 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.
         *
         * STUB
         * Overridden in LocalFile
         * @return bool
         */
        public function nextHistoryLine() {
                return false;
        }

        /**
         * Reset the history pointer to the first element of the history.
         * Always call this function after using nextHistoryLine() to free db resources
         * STUB
         * Overridden in LocalFile.
         */
        public 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.
         *
         * @return string
         */
        function getHashPath() {
                if ( !isset( $this->hashPath ) ) {
                        $this->assertRepoDefined();
                        $this->hashPath = $this->repo->getHashPath( $this->getName() );
                }

                return $this->hashPath;
        }

        /**
         * Get the path of the file relative to the public zone root.
         * This function is overriden in OldLocalFile to be like getArchiveRel().
         *
         * @return string
         */
        function getRel() {
                return $this->getHashPath() . $this->getName();
        }

        /**
         * Get the path of an archived file relative to the public zone root
         *
         * @param bool|string $suffix If not false, the name of an archived thumbnail file
         *
         * @return string
         */
        function getArchiveRel( $suffix = false ) {
                $path = 'archive/' . $this->getHashPath();
                if ( $suffix === false ) {
                        $path = substr( $path, 0, -1 );
                } else {
                        $path .= $suffix;
                }

                return $path;
        }

        /**
         * Get the path, relative to the thumbnail zone root, of the
         * thumbnail directory or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getThumbRel( $suffix = false ) {
                $path = $this->getRel();
                if ( $suffix !== false ) {
                        $path .= '/' . $suffix;
                }

                return $path;
        }

        /**
         * Get urlencoded path of the file relative to the public zone root.
         * This function is overriden in OldLocalFile to be like getArchiveUrl().
         *
         * @return string
         */
        function getUrlRel() {
                return $this->getHashPath() . rawurlencode( $this->getName() );
        }

        /**
         * Get the path, relative to the thumbnail zone root, for an archived file's thumbs directory
         * or a specific thumb if the $suffix is given.
         *
         * @param string $archiveName The timestamped name of an archived image
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getArchiveThumbRel( $archiveName, $suffix = false ) {
                $path = 'archive/' . $this->getHashPath() . $archiveName . "/";
                if ( $suffix === false ) {
                        $path = substr( $path, 0, -1 );
                } else {
                        $path .= $suffix;
                }

                return $path;
        }

        /**
         * Get the path of the archived file.
         *
         * @param bool|string $suffix If not false, the name of an archived file.
         * @return string
         */
        function getArchivePath( $suffix = false ) {
                $this->assertRepoDefined();

                return $this->repo->getZonePath( 'public' ) . '/' . $this->getArchiveRel( $suffix );
        }

        /**
         * Get the path of an archived file's thumbs, or a particular thumb if $suffix is specified
         *
         * @param string $archiveName The timestamped name of an archived image
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getArchiveThumbPath( $archiveName, $suffix = false ) {
                $this->assertRepoDefined();

                return $this->repo->getZonePath( 'thumb' ) . '/' .
                $this->getArchiveThumbRel( $archiveName, $suffix );
        }

        /**
         * Get the path of the thumbnail directory, or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getThumbPath( $suffix = false ) {
                $this->assertRepoDefined();

                return $this->repo->getZonePath( 'thumb' ) . '/' . $this->getThumbRel( $suffix );
        }

        /**
         * Get the path of the transcoded directory, or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of a media file
         * @return string
         */
        function getTranscodedPath( $suffix = false ) {
                $this->assertRepoDefined();

                return $this->repo->getZonePath( 'transcoded' ) . '/' . $this->getThumbRel( $suffix );
        }

        /**
         * Get the URL of the archive directory, or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of an archived file
         * @return string
         */
        function getArchiveUrl( $suffix = false ) {
                $this->assertRepoDefined();
                $ext = $this->getExtension();
                $path = $this->repo->getZoneUrl( 'public', $ext ) . '/archive/' . $this->getHashPath();
                if ( $suffix === false ) {
                        $path = substr( $path, 0, -1 );
                } else {
                        $path .= rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the URL of the archived file's thumbs, or a particular thumb if $suffix is specified
         *
         * @param string $archiveName The timestamped name of an archived image
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getArchiveThumbUrl( $archiveName, $suffix = false ) {
                $this->assertRepoDefined();
                $ext = $this->getExtension();
                $path = $this->repo->getZoneUrl( 'thumb', $ext ) . '/archive/' .
                        $this->getHashPath() . rawurlencode( $archiveName ) . "/";
                if ( $suffix === false ) {
                        $path = substr( $path, 0, -1 );
                } else {
                        $path .= rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the URL of the zone directory, or a particular file if $suffix is specified
         *
         * @param string $zone Name of requested zone
         * @param bool|string $suffix If not false, the name of a file in zone
         * @return string path
         */
        function getZoneUrl( $zone, $suffix = false ) {
                $this->assertRepoDefined();
                $ext = $this->getExtension();
                $path = $this->repo->getZoneUrl( $zone, $ext ) . '/' . $this->getUrlRel();
                if ( $suffix !== false ) {
                        $path .= '/' . rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the URL of the thumbnail directory, or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string path
         */
        function getThumbUrl( $suffix = false ) {
                return $this->getZoneUrl( 'thumb', $suffix );
        }

        /**
         * Get the URL of the transcoded directory, or a particular file if $suffix is specified
         *
         * @param bool|string $suffix If not false, the name of a media file
         * @return string path
         */
        function getTranscodedUrl( $suffix = false ) {
                return $this->getZoneUrl( 'transcoded', $suffix );
        }

        /**
         * Get the public zone virtual URL for a current version source file
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getVirtualUrl( $suffix = false ) {
                $this->assertRepoDefined();
                $path = $this->repo->getVirtualUrl() . '/public/' . $this->getUrlRel();
                if ( $suffix !== false ) {
                        $path .= '/' . rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the public zone virtual URL for an archived version source file
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getArchiveVirtualUrl( $suffix = false ) {
                $this->assertRepoDefined();
                $path = $this->repo->getVirtualUrl() . '/public/archive/' . $this->getHashPath();
                if ( $suffix === false ) {
                        $path = substr( $path, 0, -1 );
                } else {
                        $path .= rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the virtual URL for a thumbnail file or directory
         *
         * @param bool|string $suffix If not false, the name of a thumbnail file
         * @return string
         */
        function getThumbVirtualUrl( $suffix = false ) {
                $this->assertRepoDefined();
                $path = $this->repo->getVirtualUrl() . '/thumb/' . $this->getUrlRel();
                if ( $suffix !== false ) {
                        $path .= '/' . rawurlencode( $suffix );
                }

                return $path;
        }

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

                return (bool)$this->repo->getHashLevels();
        }

        /**
         * @throws MWException
         */
        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
         * @param string $oldver
         * @param string $desc
         * @param string $license
         * @param string $copyStatus
         * @param string $source
         * @param bool $watch
         * @param string|bool $timestamp
         * @param null|User $user User object or null to use $wgUser
         * @return bool
         * @throws MWException
         */
        function recordUpload( $oldver, $desc, $license = '', $copyStatus = '', $source = '',
                $watch = false, $timestamp = false, User $user = null
        ) {
                $this->readOnlyError();
        }

        /**
         * Move or copy a file to its public location. If a file exists at the
         * destination, move it to an archive. Returns a FileRepoStatus object with
         * the archive name in the "value" member on success.
         *
         * The archive name should be passed through to recordUpload for database
         * registration.
         *
         * Options to $options include:
         *   - headers : name/value map of HTTP headers to use in response to GET/HEAD requests
         *
         * @param string $srcPath Local filesystem path to the source image
         * @param int $flags A bitwise combination of:
         *   File::DELETE_SOURCE    Delete the source file, i.e. move rather than copy
         * @param array $options Optional additional parameters
         * @return FileRepoStatus object. On success, the value member contains the
         *   archive name, or an empty string if it was a new file.
         *
         * STUB
         * Overridden by LocalFile
         */
        function publish( $srcPath, $flags = 0, array $options = array() ) {
                $this->readOnlyError();
        }

        /**
         * @return bool
         */
        function formatMetadata() {
                if ( !$this->getHandler() ) {
                        return false;
                }

                return $this->getHandler()->formatMetadata( $this, $this->getMetadata() );
        }

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

        /**
         * Returns the name of the repository.
         *
         * @return string
         */
        function getRepoName() {
                return $this->repo ? $this->repo->getName() : 'unknown';
        }

        /**
         * Returns the repository
         *
         * @return FileRepo|LocalRepo|bool
         */
        function getRepo() {
                return $this->repo;
        }

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

        /**
         * Is this file a "deleted" file in a private archive?
         * STUB
         *
         * @param int $field One of DELETED_* bitfield constants
         * @return bool
         */
        function isDeleted( $field ) {
                return false;
        }

        /**
         * Return the deletion bitfield
         * STUB
         * @return int
         */
        function getVisibility() {
                return 0;
        }

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

                return $title && $title->isDeletedQuick();
        }

        /**
         * Move file to the new title
         *
         * Move current, old version and all thumbnails
         * to the new filename. Old file is deleted.
         *
         * Cache purging is done; checks for validity
         * and logging are caller's responsibility
         *
         * @param Title $target New file name
         * @return FileRepoStatus
         */
        function move( $target ) {
                $this->readOnlyError();
        }

        /**
         * 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 string $reason
         * @param bool $suppress Hide content from sysops?
         * @param User|null $user
         * @return bool Boolean on success, false on some kind of failure
         * STUB
         * Overridden by LocalFile
         */
        function delete( $reason, $suppress = false, $user = null ) {
                $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 array $versions Set of record ids of deleted items to restore,
         *   or empty to restore all revisions.
         * @param bool $unsuppress Remove restrictions on content upon restoration?
         * @return int|bool 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 file is a type which supports multiple pages,
         * e.g. DJVU or PDF. Note that this may be true even if the file in
         * question only has a single page.
         *
         * @return bool
         */
        function isMultipage() {
                return $this->getHandler() && $this->handler->isMultiPage( $this );
        }

        /**
         * Returns the number of pages of a multipage document, or false for
         * documents which aren't multipage documents
         *
         * @return bool|int
         */
        function pageCount() {
                if ( !isset( $this->pageCount ) ) {
                        if ( $this->getHandler() && $this->handler->isMultiPage( $this ) ) {
                                $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
         *
         * @param int $srcWidth
         * @param int $srcHeight
         * @param int $dstWidth
         *
         * @return int
         */
        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.
         *
         * @return string
         */
        function getDescriptionUrl() {
                if ( $this->repo ) {
                        return $this->repo->getDescriptionUrl( $this->getName() );
                } else {
                        return false;
                }
        }

        /**
         * Get the HTML text of the description page, if available
         *
         * @param bool|Language $lang Optional language to fetch description in
         * @return string
         */
        function getDescriptionText( $lang = false ) {
                global $wgMemc, $wgLang;
                if ( !$this->repo || !$this->repo->fetchDescription ) {
                        return false;
                }
                if ( !$lang ) {
                        $lang = $wgLang;
                }
                $renderUrl = $this->repo->getDescriptionRenderUrl( $this->getName(), $lang->getCode() );
                if ( $renderUrl ) {
                        if ( $this->repo->descriptionCacheExpiry > 0 ) {
                                wfDebug( "Attempting to get the description from cache..." );
                                $key = $this->repo->getLocalCacheKey(
                                        'RemoteFileDescription',
                                        'url',
                                        $lang->getCode(),
                                        $this->getName()
                                );
                                $obj = $wgMemc->get( $key );
                                if ( $obj ) {
                                        wfDebug( "success!\n" );

                                        return $obj;
                                }
                                wfDebug( "miss\n" );
                        }
                        wfDebug( "Fetching shared description from $renderUrl\n" );
                        $res = Http::get( $renderUrl );
                        if ( $res && $this->repo->descriptionCacheExpiry > 0 ) {
                                $wgMemc->set( $key, $res, $this->repo->descriptionCacheExpiry );
                        }

                        return $res;
                } else {
                        return false;
                }
        }

        /**
         * Get description of file revision
         * STUB
         *
         * @param int $audience One of:
         *   File::FOR_PUBLIC       to be displayed to all users
         *   File::FOR_THIS_USER    to be displayed to the given user
         *   File::RAW              get the description regardless of permissions
         * @param User $user User object to check for, only if FOR_THIS_USER is
         *   passed to the $audience parameter
         * @return string
         */
        function getDescription( $audience = self::FOR_PUBLIC, User $user = null ) {
                return null;
        }

        /**
         * Get the 14-character timestamp of the file upload
         *
         * @return string|bool TS_MW timestamp or false on failure
         */
        function getTimestamp() {
                $this->assertRepoDefined();

                return $this->repo->getFileTimestamp( $this->getPath() );
        }

        /**
         * Get the SHA-1 base 36 hash of the file
         *
         * @return string
         */
        function getSha1() {
                $this->assertRepoDefined();

                return $this->repo->getFileSha1( $this->getPath() );
        }

        /**
         * Get the deletion archive key, "<sha1>.<ext>"
         *
         * @return string
         */
        function getStorageKey() {
                $hash = $this->getSha1();
                if ( !$hash ) {
                        return false;
                }
                $ext = $this->getExtension();
                $dotExt = $ext === '' ? '' : ".$ext";

                return $hash . $dotExt;
        }

        /**
         * 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
         * @param User $user User object to check, or null to use $wgUser
         * @return bool
         */
        function userCan( $field, User $user = null ) {
                return true;
        }

        /**
         * Get an associative array containing information about a file in the local filesystem.
         *
         * @param string $path Absolute local filesystem path
         * @param string|bool $ext The file extension, or true to extract it from
         *   the filename. Set it to false to ignore the extension.
         *
         * @return array
         * @deprecated since 1.19
         */
        static function getPropsFromPath( $path, $ext = true ) {
                wfDebug( __METHOD__ . ": Getting file info for $path\n" );
                wfDeprecated( __METHOD__, '1.19' );

                $fsFile = new FSFile( $path );

                return $fsFile->getProps();
        }

        /**
         * Get a SHA-1 hash of a file in the local filesystem, in base-36 lower case
         * encoding, zero padded to 31 digits.
         *
         * 160 log 2 / log 36 = 30.95, so the 160-bit hash fills 31 digits in base 36
         * fairly neatly.
         *
         * @param string $path
         * @return bool|string False on failure
         * @deprecated since 1.19
         */
        static function sha1Base36( $path ) {
                wfDeprecated( __METHOD__, '1.19' );

                $fsFile = new FSFile( $path );

                return $fsFile->getSha1Base36();
        }

        /**
         * @return array HTTP header name/value map to use for HEAD/GET request responses
         */
        function getStreamHeaders() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getStreamHeaders( $this->getMetadata() );
                } else {
                        return array();
                }
        }

        /**
         * @return string
         */
        function getLongDesc() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getLongDesc( $this );
                } else {
                        return MediaHandler::getGeneralLongDesc( $this );
                }
        }

        /**
         * @return string
         */
        function getShortDesc() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getShortDesc( $this );
                } else {
                        return MediaHandler::getGeneralShortDesc( $this );
                }
        }

        /**
         * @return string
         */
        function getDimensionsString() {
                $handler = $this->getHandler();
                if ( $handler ) {
                        return $handler->getDimensionsString( $this );
                } else {
                        return '';
                }
        }

        /**
         * @return string
         */
        function getRedirected() {
                return $this->redirected;
        }

        /**
         * @return Title|null
         */
        function getRedirectedTitle() {
                if ( $this->redirected ) {
                        if ( !$this->redirectTitle ) {
                                $this->redirectTitle = Title::makeTitle( NS_FILE, $this->redirected );
                        }

                        return $this->redirectTitle;
                }

                return null;
        }

        /**
         * @param string $from
         * @return void
         */
        function redirectedFrom( $from ) {
                $this->redirected = $from;
        }

        /**
         * @return bool
         */
        function isMissing() {
                return false;
        }

        /**
         * Check if this file object is small and can be cached
         * @return bool
         */
        public function isCacheable() {
                return true;
        }

        /**
         * Assert that $this->repo is set to a valid FileRepo instance
         * @throws MWException
         */
        protected function assertRepoDefined() {
                if ( !( $this->repo instanceof $this->repoClass ) ) {
                        throw new MWException( "A {$this->repoClass} object is not set for this File.\n" );
                }
        }

        /**
         * Assert that $this->title is set to a Title
         * @throws MWException
         */
        protected function assertTitleDefined() {
                if ( !( $this->title instanceof Title ) ) {
                        throw new MWException( "A Title object is not set for this File.\n" );
                }
        }
}