PHPSessionHandler: Implement SessionHandlerInterface

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

<?php
/**
 * @defgroup FileRepo File Repository
 *
 * @brief This module handles how MediaWiki interacts with filesystems.
 *
 * @details
 */

/**
 * Base code for file repositories.
 *
 * 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 FileRepo
 */

/**
 * Base class for file repositories
 *
 * @ingroup FileRepo
 */
class FileRepo {
        const DELETE_SOURCE = 1;
        const OVERWRITE = 2;
        const OVERWRITE_SAME = 4;
        const SKIP_LOCKING = 8;

        const NAME_AND_TIME_ONLY = 1;

        /** @var bool Whether to fetch commons image description pages and display
         *    them on the local wiki */
        public $fetchDescription;

        /** @var int */
        public $descriptionCacheExpiry;

        /** @var bool */
        protected $hasSha1Storage = false;

        /** @var bool */
        protected $supportsSha1URLs = false;

        /** @var FileBackend */
        protected $backend;

        /** @var array Map of zones to config */
        protected $zones = array();

        /** @var string URL of thumb.php */
        protected $thumbScriptUrl;

        /** @var bool Whether to skip media file transformation on parse and rely
         *    on a 404 handler instead. */
        protected $transformVia404;

        /** @var string URL of image description pages, e.g.
         *    https://en.wikipedia.org/wiki/File:
         */
        protected $descBaseUrl;

        /** @var string URL of the MediaWiki installation, equivalent to
         *    $wgScriptPath, e.g. https://en.wikipedia.org/w
         */
        protected $scriptDirUrl;

        /** @var string Script extension of the MediaWiki installation, equivalent
         *    to the old $wgScriptExtension, e.g. .php5 defaults to .php */
        protected $scriptExtension;

        /** @var string Equivalent to $wgArticlePath, e.g. https://en.wikipedia.org/wiki/$1 */
        protected $articleUrl;

        /** @var bool Equivalent to $wgCapitalLinks (or $wgCapitalLinkOverrides[NS_FILE],
         *    determines whether filenames implicitly start with a capital letter.
         *    The current implementation may give incorrect description page links
         *    when the local $wgCapitalLinks and initialCapital are mismatched.
         */
        protected $initialCapital;

        /** @var string May be 'paranoid' to remove all parameters from error
         *    messages, 'none' to leave the paths in unchanged, or 'simple' to
         *    replace paths with placeholders. Default for LocalRepo is
         *    'simple'.
         */
        protected $pathDisclosureProtection = 'simple';

        /** @var bool Public zone URL. */
        protected $url;

        /** @var string The base thumbnail URL. Defaults to "<url>/thumb". */
        protected $thumbUrl;

        /** @var int The number of directory levels for hash-based division of files */
        protected $hashLevels;

        /** @var int The number of directory levels for hash-based division of deleted files */
        protected $deletedHashLevels;

        /** @var int File names over this size will use the short form of thumbnail
         *    names. Short thumbnail names only have the width, parameters, and the
         *    extension.
         */
        protected $abbrvThreshold;

        /** @var string The URL of the repo's favicon, if any */
        protected $favicon;

        /** @var bool Whether all zones should be private (e.g. private wiki repo) */
        protected $isPrivate;

        /** @var array callable Override these in the base class */
        protected $fileFactory = array( 'UnregisteredLocalFile', 'newFromTitle' );
        /** @var array callable|bool Override these in the base class */
        protected $oldFileFactory = false;
        /** @var array callable|bool Override these in the base class */
        protected $fileFactoryKey = false;
        /** @var array callable|bool Override these in the base class */
        protected $oldFileFactoryKey = false;

        /**
         * @param array|null $info
         * @throws MWException
         */
        public function __construct( array $info = null ) {
                // Verify required settings presence
                if (
                        $info === null
                        || !array_key_exists( 'name', $info )
                        || !array_key_exists( 'backend', $info )
                ) {
                        throw new MWException( __CLASS__ .
                                " requires an array of options having both 'name' and 'backend' keys.\n" );
                }

                // Required settings
                $this->name = $info['name'];
                if ( $info['backend'] instanceof FileBackend ) {
                        $this->backend = $info['backend']; // useful for testing
                } else {
                        $this->backend = FileBackendGroup::singleton()->get( $info['backend'] );
                }

                // Optional settings that can have no value
                $optionalSettings = array(
                        'descBaseUrl', 'scriptDirUrl', 'articleUrl', 'fetchDescription',
                        'thumbScriptUrl', 'pathDisclosureProtection', 'descriptionCacheExpiry',
                        'scriptExtension', 'favicon'
                );
                foreach ( $optionalSettings as $var ) {
                        if ( isset( $info[$var] ) ) {
                                $this->$var = $info[$var];
                        }
                }

                // Optional settings that have a default
                $this->initialCapital = isset( $info['initialCapital'] )
                        ? $info['initialCapital']
                        : MWNamespace::isCapitalized( NS_FILE );
                $this->url = isset( $info['url'] )
                        ? $info['url']
                        : false; // a subclass may set the URL (e.g. ForeignAPIRepo)
                if ( isset( $info['thumbUrl'] ) ) {
                        $this->thumbUrl = $info['thumbUrl'];
                } else {
                        $this->thumbUrl = $this->url ? "{$this->url}/thumb" : false;
                }
                $this->hashLevels = isset( $info['hashLevels'] )
                        ? $info['hashLevels']
                        : 2;
                $this->deletedHashLevels = isset( $info['deletedHashLevels'] )
                        ? $info['deletedHashLevels']
                        : $this->hashLevels;
                $this->transformVia404 = !empty( $info['transformVia404'] );
                $this->abbrvThreshold = isset( $info['abbrvThreshold'] )
                        ? $info['abbrvThreshold']
                        : 255;
                $this->isPrivate = !empty( $info['isPrivate'] );
                // Give defaults for the basic zones...
                $this->zones = isset( $info['zones'] ) ? $info['zones'] : array();
                foreach ( array( 'public', 'thumb', 'transcoded', 'temp', 'deleted' ) as $zone ) {
                        if ( !isset( $this->zones[$zone]['container'] ) ) {
                                $this->zones[$zone]['container'] = "{$this->name}-{$zone}";
                        }
                        if ( !isset( $this->zones[$zone]['directory'] ) ) {
                                $this->zones[$zone]['directory'] = '';
                        }
                        if ( !isset( $this->zones[$zone]['urlsByExt'] ) ) {
                                $this->zones[$zone]['urlsByExt'] = array();
                        }
                }

                $this->supportsSha1URLs = !empty( $info['supportsSha1URLs'] );
        }

        /**
         * Get the file backend instance. Use this function wisely.
         *
         * @return FileBackend
         */
        public function getBackend() {
                return $this->backend;
        }

        /**
         * Get an explanatory message if this repo is read-only.
         * This checks if an administrator disabled writes to the backend.
         *
         * @return string|bool Returns false if the repo is not read-only
         */
        public function getReadOnlyReason() {
                return $this->backend->getReadOnlyReason();
        }

        /**
         * Check if a single zone or list of zones is defined for usage
         *
         * @param array $doZones Only do a particular zones
         * @throws MWException
         * @return Status
         */
        protected function initZones( $doZones = array() ) {
                $status = $this->newGood();
                foreach ( (array)$doZones as $zone ) {
                        $root = $this->getZonePath( $zone );
                        if ( $root === null ) {
                                throw new MWException( "No '$zone' zone defined in the {$this->name} repo." );
                        }
                }

                return $status;
        }

        /**
         * Determine if a string is an mwrepo:// URL
         *
         * @param string $url
         * @return bool
         */
        public static function isVirtualUrl( $url ) {
                return substr( $url, 0, 9 ) == 'mwrepo://';
        }

        /**
         * Get a URL referring to this repository, with the private mwrepo protocol.
         * The suffix, if supplied, is considered to be unencoded, and will be
         * URL-encoded before being returned.
         *
         * @param string|bool $suffix
         * @return string
         */
        public function getVirtualUrl( $suffix = false ) {
                $path = 'mwrepo://' . $this->name;
                if ( $suffix !== false ) {
                        $path .= '/' . rawurlencode( $suffix );
                }

                return $path;
        }

        /**
         * Get the URL corresponding to one of the four basic zones
         *
         * @param string $zone One of: public, deleted, temp, thumb
         * @param string|null $ext Optional file extension
         * @return string|bool
         */
        public function getZoneUrl( $zone, $ext = null ) {
                if ( in_array( $zone, array( 'public', 'thumb', 'transcoded' ) ) ) {
                        // standard public zones
                        if ( $ext !== null && isset( $this->zones[$zone]['urlsByExt'][$ext] ) ) {
                                // custom URL for extension/zone
                                return $this->zones[$zone]['urlsByExt'][$ext];
                        } elseif ( isset( $this->zones[$zone]['url'] ) ) {
                                // custom URL for zone
                                return $this->zones[$zone]['url'];
                        }
                }
                switch ( $zone ) {
                        case 'public':
                                return $this->url;
                        case 'temp':
                        case 'deleted':
                                return false; // no public URL
                        case 'thumb':
                                return $this->thumbUrl;
                        case 'transcoded':
                                return "{$this->url}/transcoded";
                        default:
                                return false;
                }
        }

        /**
         * @return bool Whether non-ASCII path characters are allowed
         */
        public function backendSupportsUnicodePaths() {
                return ( $this->getBackend()->getFeatures() & FileBackend::ATTR_UNICODE_PATHS );
        }

        /**
         * Get the backend storage path corresponding to a virtual URL.
         * Use this function wisely.
         *
         * @param string $url
         * @throws MWException
         * @return string
         */
        public function resolveVirtualUrl( $url ) {
                if ( substr( $url, 0, 9 ) != 'mwrepo://' ) {
                        throw new MWException( __METHOD__ . ': unknown protocol' );
                }
                $bits = explode( '/', substr( $url, 9 ), 3 );
                if ( count( $bits ) != 3 ) {
                        throw new MWException( __METHOD__ . ": invalid mwrepo URL: $url" );
                }
                list( $repo, $zone, $rel ) = $bits;
                if ( $repo !== $this->name ) {
                        throw new MWException( __METHOD__ . ": fetching from a foreign repo is not supported" );
                }
                $base = $this->getZonePath( $zone );
                if ( !$base ) {
                        throw new MWException( __METHOD__ . ": invalid zone: $zone" );
                }

                return $base . '/' . rawurldecode( $rel );
        }

        /**
         * The the storage container and base path of a zone
         *
         * @param string $zone
         * @return array (container, base path) or (null, null)
         */
        protected function getZoneLocation( $zone ) {
                if ( !isset( $this->zones[$zone] ) ) {
                        return array( null, null ); // bogus
                }

                return array( $this->zones[$zone]['container'], $this->zones[$zone]['directory'] );
        }

        /**
         * Get the storage path corresponding to one of the zones
         *
         * @param string $zone
         * @return string|null Returns null if the zone is not defined
         */
        public function getZonePath( $zone ) {
                list( $container, $base ) = $this->getZoneLocation( $zone );
                if ( $container === null || $base === null ) {
                        return null;
                }
                $backendName = $this->backend->getName();
                if ( $base != '' ) { // may not be set
                        $base = "/{$base}";
                }

                return "mwstore://$backendName/{$container}{$base}";
        }

        /**
         * Create a new File object from the local repository
         *
         * @param Title|string $title Title object or string
         * @param bool|string $time Time at which the image was uploaded. If this
         *   is specified, the returned object will be an instance of the
         *   repository's old file class instead of a current file. Repositories
         *   not supporting version control should return false if this parameter
         *   is set.
         * @return File|null A File, or null if passed an invalid Title
         */
        public function newFile( $title, $time = false ) {
                $title = File::normalizeTitle( $title );
                if ( !$title ) {
                        return null;
                }
                if ( $time ) {
                        if ( $this->oldFileFactory ) {
                                return call_user_func( $this->oldFileFactory, $title, $this, $time );
                        } else {
                                return false;
                        }
                } else {
                        return call_user_func( $this->fileFactory, $title, $this );
                }
        }

        /**
         * Find an instance of the named file created at the specified time
         * Returns false if the file does not exist. Repositories not supporting
         * version control should return false if the time is specified.
         *
         * @param Title|string $title Title object or string
         * @param array $options Associative array of options:
         *   time:           requested time for a specific file version, or false for the
         *                   current version. An image object will be returned which was
         *                   created at the specified time (which may be archived or current).
         *   ignoreRedirect: If true, do not follow file redirects
         *   private:        If true, return restricted (deleted) files if the current
         *                   user is allowed to view them. Otherwise, such files will not
         *                   be found. If a User object, use that user instead of the current.
         *   latest:         If true, load from the latest available data into File objects
         * @return File|bool False on failure
         */
        public function findFile( $title, $options = array() ) {
                $title = File::normalizeTitle( $title );
                if ( !$title ) {
                        return false;
                }
                if ( isset( $options['bypassCache'] ) ) {
                        $options['latest'] = $options['bypassCache']; // b/c
                }
                $time = isset( $options['time'] ) ? $options['time'] : false;
                $flags = !empty( $options['latest'] ) ? File::READ_LATEST : 0;
                # First try the current version of the file to see if it precedes the timestamp
                $img = $this->newFile( $title );
                if ( !$img ) {
                        return false;
                }
                $img->load( $flags );
                if ( $img->exists() && ( !$time || $img->getTimestamp() == $time ) ) {
                        return $img;
                }
                # Now try an old version of the file
                if ( $time !== false ) {
                        $img = $this->newFile( $title, $time );
                        if ( $img ) {
                                $img->load( $flags );
                                if ( $img->exists() ) {
                                        if ( !$img->isDeleted( File::DELETED_FILE ) ) {
                                                return $img; // always OK
                                        } elseif ( !empty( $options['private'] ) &&
                                                $img->userCan( File::DELETED_FILE,
                                                        $options['private'] instanceof User ? $options['private'] : null
                                                )
                                        ) {
                                                return $img;
                                        }
                                }
                        }
                }

                # Now try redirects
                if ( !empty( $options['ignoreRedirect'] ) ) {
                        return false;
                }
                $redir = $this->checkRedirect( $title );
                if ( $redir && $title->getNamespace() == NS_FILE ) {
                        $img = $this->newFile( $redir );
                        if ( !$img ) {
                                return false;
                        }
                        $img->load( $flags );
                        if ( $img->exists() ) {
                                $img->redirectedFrom( $title->getDBkey() );

                                return $img;
                        }
                }

                return false;
        }

        /**
         * Find many files at once.
         *
         * @param array $items An array of titles, or an array of findFile() options with
         *    the "title" option giving the title. Example:
         *
         *     $findItem = array( 'title' => $title, 'private' => true );
         *     $findBatch = array( $findItem );
         *     $repo->findFiles( $findBatch );
         *
         *    No title should appear in $items twice, as the result use titles as keys
         * @param int $flags Supports:
         *     - FileRepo::NAME_AND_TIME_ONLY : return a (search title => (title,timestamp)) map.
         *       The search title uses the input titles; the other is the final post-redirect title.
         *       All titles are returned as string DB keys and the inner array is associative.
         * @return array Map of (file name => File objects) for matches
         */
        public function findFiles( array $items, $flags = 0 ) {
                $result = array();
                foreach ( $items as $item ) {
                        if ( is_array( $item ) ) {
                                $title = $item['title'];
                                $options = $item;
                                unset( $options['title'] );
                        } else {
                                $title = $item;
                                $options = array();
                        }
                        $file = $this->findFile( $title, $options );
                        if ( $file ) {
                                $searchName = File::normalizeTitle( $title )->getDBkey(); // must be valid
                                if ( $flags & self::NAME_AND_TIME_ONLY ) {
                                        $result[$searchName] = array(
                                                'title' => $file->getTitle()->getDBkey(),
                                                'timestamp' => $file->getTimestamp()
                                        );
                                } else {
                                        $result[$searchName] = $file;
                                }
                        }
                }

                return $result;
        }

        /**
         * Find an instance of the file with this key, created at the specified time
         * Returns false if the file does not exist. Repositories not supporting
         * version control should return false if the time is specified.
         *
         * @param string $sha1 Base 36 SHA-1 hash
         * @param array $options Option array, same as findFile().
         * @return File|bool False on failure
         */
        public function findFileFromKey( $sha1, $options = array() ) {
                $time = isset( $options['time'] ) ? $options['time'] : false;
                # First try to find a matching current version of a file...
                if ( $this->fileFactoryKey ) {
                        $img = call_user_func( $this->fileFactoryKey, $sha1, $this, $time );
                } else {
                        return false; // find-by-sha1 not supported
                }
                if ( $img && $img->exists() ) {
                        return $img;
                }
                # Now try to find a matching old version of a file...
                if ( $time !== false && $this->oldFileFactoryKey ) { // find-by-sha1 supported?
                        $img = call_user_func( $this->oldFileFactoryKey, $sha1, $this, $time );
                        if ( $img && $img->exists() ) {
                                if ( !$img->isDeleted( File::DELETED_FILE ) ) {
                                        return $img; // always OK
                                } elseif ( !empty( $options['private'] ) &&
                                        $img->userCan( File::DELETED_FILE,
                                                $options['private'] instanceof User ? $options['private'] : null
                                        )
                                ) {
                                        return $img;
                                }
                        }
                }

                return false;
        }

        /**
         * Get an array or iterator of file objects for files that have a given
         * SHA-1 content hash.
         *
         * STUB
         * @param string $hash SHA-1 hash
         * @return File[]
         */
        public function findBySha1( $hash ) {
                return array();
        }

        /**
         * Get an array of arrays or iterators of file objects for files that
         * have the given SHA-1 content hashes.
         *
         * @param array $hashes An array of hashes
         * @return array An Array of arrays or iterators of file objects and the hash as key
         */
        public function findBySha1s( array $hashes ) {
                $result = array();
                foreach ( $hashes as $hash ) {
                        $files = $this->findBySha1( $hash );
                        if ( count( $files ) ) {
                                $result[$hash] = $files;
                        }
                }

                return $result;
        }

        /**
         * Return an array of files where the name starts with $prefix.
         *
         * STUB
         * @param string $prefix The prefix to search for
         * @param int $limit The maximum amount of files to return
         * @return array
         */
        public function findFilesByPrefix( $prefix, $limit ) {
                return array();
        }

        /**
         * Get the URL of thumb.php
         *
         * @return string
         */
        public function getThumbScriptUrl() {
                return $this->thumbScriptUrl;
        }

        /**
         * Returns true if the repository can transform files via a 404 handler
         *
         * @return bool
         */
        public function canTransformVia404() {
                return $this->transformVia404;
        }

        /**
         * Get the name of a file from its title object
         *
         * @param Title $title
         * @return string
         */
        public function getNameFromTitle( Title $title ) {
                global $wgContLang;
                if ( $this->initialCapital != MWNamespace::isCapitalized( NS_FILE ) ) {
                        $name = $title->getUserCaseDBKey();
                        if ( $this->initialCapital ) {
                                $name = $wgContLang->ucfirst( $name );
                        }
                } else {
                        $name = $title->getDBkey();
                }

                return $name;
        }

        /**
         * Get the public zone root storage directory of the repository
         *
         * @return string
         */
        public function getRootDirectory() {
                return $this->getZonePath( 'public' );
        }

        /**
         * Get a relative path including trailing slash, e.g. f/fa/
         * If the repo is not hashed, returns an empty string
         *
         * @param string $name Name of file
         * @return string
         */
        public function getHashPath( $name ) {
                return self::getHashPathForLevel( $name, $this->hashLevels );
        }

        /**
         * Get a relative path including trailing slash, e.g. f/fa/
         * If the repo is not hashed, returns an empty string
         *
         * @param string $suffix Basename of file from FileRepo::storeTemp()
         * @return string
         */
        public function getTempHashPath( $suffix ) {
                $parts = explode( '!', $suffix, 2 ); // format is <timestamp>!<name> or just <name>
                $name = isset( $parts[1] ) ? $parts[1] : $suffix; // hash path is not based on timestamp
                return self::getHashPathForLevel( $name, $this->hashLevels );
        }

        /**
         * @param string $name
         * @param int $levels
         * @return string
         */
        protected static function getHashPathForLevel( $name, $levels ) {
                if ( $levels == 0 ) {
                        return '';
                } else {
                        $hash = md5( $name );
                        $path = '';
                        for ( $i = 1; $i <= $levels; $i++ ) {
                                $path .= substr( $hash, 0, $i ) . '/';
                        }

                        return $path;
                }
        }

        /**
         * Get the number of hash directory levels
         *
         * @return int
         */
        public function getHashLevels() {
                return $this->hashLevels;
        }

        /**
         * Get the name of this repository, as specified by $info['name]' to the constructor
         *
         * @return string
         */
        public function getName() {
                return $this->name;
        }

        /**
         * Make an url to this repo
         *
         * @param string $query Query string to append
         * @param string $entry Entry point; defaults to index
         * @return string|bool False on failure
         */
        public function makeUrl( $query = '', $entry = 'index' ) {
                if ( isset( $this->scriptDirUrl ) ) {
                        $ext = isset( $this->scriptExtension ) ? $this->scriptExtension : '.php';

                        return wfAppendQuery( "{$this->scriptDirUrl}/{$entry}{$ext}", $query );
                }

                return false;
        }

        /**
         * Get the URL of an image description page. May return false if it is
         * unknown or not applicable. In general this should only be called by the
         * File class, since it may return invalid results for certain kinds of
         * repositories. Use File::getDescriptionUrl() in user code.
         *
         * In particular, it uses the article paths as specified to the repository
         * constructor, whereas local repositories use the local Title functions.
         *
         * @param string $name
         * @return string
         */
        public function getDescriptionUrl( $name ) {
                $encName = wfUrlencode( $name );
                if ( !is_null( $this->descBaseUrl ) ) {
                        # "http://example.com/wiki/File:"
                        return $this->descBaseUrl . $encName;
                }
                if ( !is_null( $this->articleUrl ) ) {
                        # "http://example.com/wiki/$1"
                        # We use "Image:" as the canonical namespace for
                        # compatibility across all MediaWiki versions.
                        return str_replace( '$1',
                                "Image:$encName", $this->articleUrl );
                }
                if ( !is_null( $this->scriptDirUrl ) ) {
                        # "http://example.com/w"
                        # We use "Image:" as the canonical namespace for
                        # compatibility across all MediaWiki versions,
                        # and just sort of hope index.php is right. ;)
                        return $this->makeUrl( "title=Image:$encName" );
                }

                return false;
        }

        /**
         * Get the URL of the content-only fragment of the description page. For
         * MediaWiki this means action=render. This should only be called by the
         * repository's file class, since it may return invalid results. User code
         * should use File::getDescriptionText().
         *
         * @param string $name Name of image to fetch
         * @param string $lang Language to fetch it in, if any.
         * @return string
         */
        public function getDescriptionRenderUrl( $name, $lang = null ) {
                $query = 'action=render';
                if ( !is_null( $lang ) ) {
                        $query .= '&uselang=' . $lang;
                }
                if ( isset( $this->scriptDirUrl ) ) {
                        return $this->makeUrl(
                                'title=' .
                                wfUrlencode( 'Image:' . $name ) .
                                "&$query" );
                } else {
                        $descUrl = $this->getDescriptionUrl( $name );
                        if ( $descUrl ) {
                                return wfAppendQuery( $descUrl, $query );
                        } else {
                                return false;
                        }
                }
        }

        /**
         * Get the URL of the stylesheet to apply to description pages
         *
         * @return string|bool False on failure
         */
        public function getDescriptionStylesheetUrl() {
                if ( isset( $this->scriptDirUrl ) ) {
                        return $this->makeUrl( 'title=MediaWiki:Filepage.css&' .
                                wfArrayToCgi( Skin::getDynamicStylesheetQuery() ) );
                }

                return false;
        }

        /**
         * Store a file to a given destination.
         *
         * @param string $srcPath Source file system path, storage path, or virtual URL
         * @param string $dstZone Destination zone
         * @param string $dstRel Destination relative path
         * @param int $flags Bitwise combination of the following flags:
         *   self::DELETE_SOURCE     Delete the source file after upload
         *   self::OVERWRITE         Overwrite an existing destination file instead of failing
         *   self::OVERWRITE_SAME    Overwrite the file if the destination exists and has the
         *                           same contents as the source
         *   self::SKIP_LOCKING      Skip any file locking when doing the store
         * @return FileRepoStatus
         */
        public function store( $srcPath, $dstZone, $dstRel, $flags = 0 ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->storeBatch( array( array( $srcPath, $dstZone, $dstRel ) ), $flags );
                if ( $status->successCount == 0 ) {
                        $status->ok = false;
                }

                return $status;
        }

        /**
         * Store a batch of files
         *
         * @param array $triplets (src, dest zone, dest rel) triplets as per store()
         * @param int $flags Bitwise combination of the following flags:
         *   self::DELETE_SOURCE     Delete the source file after upload
         *   self::OVERWRITE         Overwrite an existing destination file instead of failing
         *   self::OVERWRITE_SAME    Overwrite the file if the destination exists and has the
         *                           same contents as the source
         *   self::SKIP_LOCKING      Skip any file locking when doing the store
         * @throws MWException
         * @return FileRepoStatus
         */
        public function storeBatch( array $triplets, $flags = 0 ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->newGood();
                $backend = $this->backend; // convenience

                $operations = array();
                $sourceFSFilesToDelete = array(); // cleanup for disk source files
                // Validate each triplet and get the store operation...
                foreach ( $triplets as $triplet ) {
                        list( $srcPath, $dstZone, $dstRel ) = $triplet;
                        wfDebug( __METHOD__
                                . "( \$src='$srcPath', \$dstZone='$dstZone', \$dstRel='$dstRel' )\n"
                        );

                        // Resolve destination path
                        $root = $this->getZonePath( $dstZone );
                        if ( !$root ) {
                                throw new MWException( "Invalid zone: $dstZone" );
                        }
                        if ( !$this->validateFilename( $dstRel ) ) {
                                throw new MWException( 'Validation error in $dstRel' );
                        }
                        $dstPath = "$root/$dstRel";
                        $dstDir = dirname( $dstPath );
                        // Create destination directories for this triplet
                        if ( !$this->initDirectory( $dstDir )->isOK() ) {
                                return $this->newFatal( 'directorycreateerror', $dstDir );
                        }

                        // Resolve source to a storage path if virtual
                        $srcPath = $this->resolveToStoragePath( $srcPath );

                        // Get the appropriate file operation
                        if ( FileBackend::isStoragePath( $srcPath ) ) {
                                $opName = ( $flags & self::DELETE_SOURCE ) ? 'move' : 'copy';
                        } else {
                                $opName = 'store';
                                if ( $flags & self::DELETE_SOURCE ) {
                                        $sourceFSFilesToDelete[] = $srcPath;
                                }
                        }
                        $operations[] = array(
                                'op' => $opName,
                                'src' => $srcPath,
                                'dst' => $dstPath,
                                'overwrite' => $flags & self::OVERWRITE,
                                'overwriteSame' => $flags & self::OVERWRITE_SAME,
                        );
                }

                // Execute the store operation for each triplet
                $opts = array( 'force' => true );
                if ( $flags & self::SKIP_LOCKING ) {
                        $opts['nonLocking'] = true;
                }
                $status->merge( $backend->doOperations( $operations, $opts ) );
                // Cleanup for disk source files...
                foreach ( $sourceFSFilesToDelete as $file ) {
                        MediaWiki\suppressWarnings();
                        unlink( $file ); // FS cleanup
                        MediaWiki\restoreWarnings();
                }

                return $status;
        }

        /**
         * Deletes a batch of files.
         * Each file can be a (zone, rel) pair, virtual url, storage path.
         * It will try to delete each file, but ignores any errors that may occur.
         *
         * @param array $files List of files to delete
         * @param int $flags Bitwise combination of the following flags:
         *   self::SKIP_LOCKING      Skip any file locking when doing the deletions
         * @return FileRepoStatus
         */
        public function cleanupBatch( array $files, $flags = 0 ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->newGood();

                $operations = array();
                foreach ( $files as $path ) {
                        if ( is_array( $path ) ) {
                                // This is a pair, extract it
                                list( $zone, $rel ) = $path;
                                $path = $this->getZonePath( $zone ) . "/$rel";
                        } else {
                                // Resolve source to a storage path if virtual
                                $path = $this->resolveToStoragePath( $path );
                        }
                        $operations[] = array( 'op' => 'delete', 'src' => $path );
                }
                // Actually delete files from storage...
                $opts = array( 'force' => true );
                if ( $flags & self::SKIP_LOCKING ) {
                        $opts['nonLocking'] = true;
                }
                $status->merge( $this->backend->doOperations( $operations, $opts ) );

                return $status;
        }

        /**
         * Import a file from the local file system into the repo.
         * This does no locking nor journaling and overrides existing files.
         * This function can be used to write to otherwise read-only foreign repos.
         * This is intended for copying generated thumbnails into the repo.
         *
         * @param string $src Source file system path, storage path, or virtual URL
         * @param string $dst Virtual URL or storage path
         * @param array|string|null $options An array consisting of a key named headers
         *   listing extra headers. If a string, taken as content-disposition header.
         *   (Support for array of options new in 1.23)
         * @return FileRepoStatus
         */
        final public function quickImport( $src, $dst, $options = null ) {
                return $this->quickImportBatch( array( array( $src, $dst, $options ) ) );
        }

        /**
         * Purge a file from the repo. This does no locking nor journaling.
         * This function can be used to write to otherwise read-only foreign repos.
         * This is intended for purging thumbnails.
         *
         * @param string $path Virtual URL or storage path
         * @return FileRepoStatus
         */
        final public function quickPurge( $path ) {
                return $this->quickPurgeBatch( array( $path ) );
        }

        /**
         * Deletes a directory if empty.
         * This function can be used to write to otherwise read-only foreign repos.
         *
         * @param string $dir Virtual URL (or storage path) of directory to clean
         * @return Status
         */
        public function quickCleanDir( $dir ) {
                $status = $this->newGood();
                $status->merge( $this->backend->clean(
                        array( 'dir' => $this->resolveToStoragePath( $dir ) ) ) );

                return $status;
        }

        /**
         * Import a batch of files from the local file system into the repo.
         * This does no locking nor journaling and overrides existing files.
         * This function can be used to write to otherwise read-only foreign repos.
         * This is intended for copying generated thumbnails into the repo.
         *
         * All path parameters may be a file system path, storage path, or virtual URL.
         * When "headers" are given they are used as HTTP headers if supported.
         *
         * @param array $triples List of (source path, destination path, disposition)
         * @return FileRepoStatus
         */
        public function quickImportBatch( array $triples ) {
                $status = $this->newGood();
                $operations = array();
                foreach ( $triples as $triple ) {
                        list( $src, $dst ) = $triple;
                        $src = $this->resolveToStoragePath( $src );
                        $dst = $this->resolveToStoragePath( $dst );

                        if ( !isset( $triple[2] ) ) {
                                $headers = array();
                        } elseif ( is_string( $triple[2] ) ) {
                                // back-compat
                                $headers = array( 'Content-Disposition' => $triple[2] );
                        } elseif ( is_array( $triple[2] ) && isset( $triple[2]['headers'] ) ) {
                                $headers = $triple[2]['headers'];
                        } else {
                                $headers = array();
                        }

                        $operations[] = array(
                                'op' => FileBackend::isStoragePath( $src ) ? 'copy' : 'store',
                                'src' => $src,
                                'dst' => $dst,
                                'headers' => $headers
                        );
                        $status->merge( $this->initDirectory( dirname( $dst ) ) );
                }
                $status->merge( $this->backend->doQuickOperations( $operations ) );

                return $status;
        }

        /**
         * Purge a batch of files from the repo.
         * This function can be used to write to otherwise read-only foreign repos.
         * This does no locking nor journaling and is intended for purging thumbnails.
         *
         * @param array $paths List of virtual URLs or storage paths
         * @return FileRepoStatus
         */
        public function quickPurgeBatch( array $paths ) {
                $status = $this->newGood();
                $operations = array();
                foreach ( $paths as $path ) {
                        $operations[] = array(
                                'op' => 'delete',
                                'src' => $this->resolveToStoragePath( $path ),
                                'ignoreMissingSource' => true
                        );
                }
                $status->merge( $this->backend->doQuickOperations( $operations ) );

                return $status;
        }

        /**
         * Pick a random name in the temp zone and store a file to it.
         * Returns a FileRepoStatus object with the file Virtual URL in the value,
         * file can later be disposed using FileRepo::freeTemp().
         *
         * @param string $originalName The base name of the file as specified
         *   by the user. The file extension will be maintained.
         * @param string $srcPath The current location of the file.
         * @return FileRepoStatus Object with the URL in the value.
         */
        public function storeTemp( $originalName, $srcPath ) {
                $this->assertWritableRepo(); // fail out if read-only

                $date = MWTimestamp::getInstance()->format( 'YmdHis' );
                $hashPath = $this->getHashPath( $originalName );
                $dstUrlRel = $hashPath . $date . '!' . rawurlencode( $originalName );
                $virtualUrl = $this->getVirtualUrl( 'temp' ) . '/' . $dstUrlRel;

                $result = $this->quickImport( $srcPath, $virtualUrl );
                $result->value = $virtualUrl;

                return $result;
        }

        /**
         * Remove a temporary file or mark it for garbage collection
         *
         * @param string $virtualUrl The virtual URL returned by FileRepo::storeTemp()
         * @return bool True on success, false on failure
         */
        public function freeTemp( $virtualUrl ) {
                $this->assertWritableRepo(); // fail out if read-only

                $temp = $this->getVirtualUrl( 'temp' );
                if ( substr( $virtualUrl, 0, strlen( $temp ) ) != $temp ) {
                        wfDebug( __METHOD__ . ": Invalid temp virtual URL\n" );

                        return false;
                }

                return $this->quickPurge( $virtualUrl )->isOK();
        }

        /**
         * Concatenate a list of temporary files into a target file location.
         *
         * @param array $srcPaths Ordered list of source virtual URLs/storage paths
         * @param string $dstPath Target file system path
         * @param int $flags Bitwise combination of the following flags:
         *   self::DELETE_SOURCE     Delete the source files
         * @return FileRepoStatus
         */
        public function concatenate( array $srcPaths, $dstPath, $flags = 0 ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->newGood();

                $sources = array();
                foreach ( $srcPaths as $srcPath ) {
                        // Resolve source to a storage path if virtual
                        $source = $this->resolveToStoragePath( $srcPath );
                        $sources[] = $source; // chunk to merge
                }

                // Concatenate the chunks into one FS file
                $params = array( 'srcs' => $sources, 'dst' => $dstPath );
                $status->merge( $this->backend->concatenate( $params ) );
                if ( !$status->isOK() ) {
                        return $status;
                }

                // Delete the sources if required
                if ( $flags & self::DELETE_SOURCE ) {
                        $status->merge( $this->quickPurgeBatch( $srcPaths ) );
                }

                // Make sure status is OK, despite any quickPurgeBatch() fatals
                $status->setResult( true );

                return $status;
        }

        /**
         * Copy or move a file either from a storage path, virtual URL,
         * or file system path, into this repository at the specified destination location.
         *
         * Returns a FileRepoStatus object. On success, the value contains "new" or
         * "archived", to indicate whether the file was new with that name.
         *
         * Options to $options include:
         *   - headers : name/value map of HTTP headers to use in response to GET/HEAD requests
         *
         * @param string $srcPath The source file system path, storage path, or URL
         * @param string $dstRel The destination relative path
         * @param string $archiveRel The relative path where the existing file is to
         *   be archived, if there is one. Relative to the public zone root.
         * @param int $flags Bitfield, may be FileRepo::DELETE_SOURCE to indicate
         *   that the source file should be deleted if possible
         * @param array $options Optional additional parameters
         * @return FileRepoStatus
         */
        public function publish(
                $srcPath, $dstRel, $archiveRel, $flags = 0, array $options = array()
        ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->publishBatch(
                        array( array( $srcPath, $dstRel, $archiveRel, $options ) ), $flags );
                if ( $status->successCount == 0 ) {
                        $status->ok = false;
                }
                if ( isset( $status->value[0] ) ) {
                        $status->value = $status->value[0];
                } else {
                        $status->value = false;
                }

                return $status;
        }

        /**
         * Publish a batch of files
         *
         * @param array $ntuples (source, dest, archive) triplets or
         *   (source, dest, archive, options) 4-tuples as per publish().
         * @param int $flags Bitfield, may be FileRepo::DELETE_SOURCE to indicate
         *   that the source files should be deleted if possible
         * @throws MWException
         * @return FileRepoStatus
         */
        public function publishBatch( array $ntuples, $flags = 0 ) {
                $this->assertWritableRepo(); // fail out if read-only

                $backend = $this->backend; // convenience
                // Try creating directories
                $status = $this->initZones( 'public' );
                if ( !$status->isOK() ) {
                        return $status;
                }

                $status = $this->newGood( array() );

                $operations = array();
                $sourceFSFilesToDelete = array(); // cleanup for disk source files
                // Validate each triplet and get the store operation...
                foreach ( $ntuples as $ntuple ) {
                        list( $srcPath, $dstRel, $archiveRel ) = $ntuple;
                        $options = isset( $ntuple[3] ) ? $ntuple[3] : array();
                        // Resolve source to a storage path if virtual
                        $srcPath = $this->resolveToStoragePath( $srcPath );
                        if ( !$this->validateFilename( $dstRel ) ) {
                                throw new MWException( 'Validation error in $dstRel' );
                        }
                        if ( !$this->validateFilename( $archiveRel ) ) {
                                throw new MWException( 'Validation error in $archiveRel' );
                        }

                        $publicRoot = $this->getZonePath( 'public' );
                        $dstPath = "$publicRoot/$dstRel";
                        $archivePath = "$publicRoot/$archiveRel";

                        $dstDir = dirname( $dstPath );
                        $archiveDir = dirname( $archivePath );
                        // Abort immediately on directory creation errors since they're likely to be repetitive
                        if ( !$this->initDirectory( $dstDir )->isOK() ) {
                                return $this->newFatal( 'directorycreateerror', $dstDir );
                        }
                        if ( !$this->initDirectory( $archiveDir )->isOK() ) {
                                return $this->newFatal( 'directorycreateerror', $archiveDir );
                        }

                        // Set any desired headers to be use in GET/HEAD responses
                        $headers = isset( $options['headers'] ) ? $options['headers'] : array();

                        // Archive destination file if it exists.
                        // This will check if the archive file also exists and fail if does.
                        // This is a sanity check to avoid data loss. On Windows and Linux,
                        // copy() will overwrite, so the existence check is vulnerable to
                        // race conditions unless a functioning LockManager is used.
                        // LocalFile also uses SELECT FOR UPDATE for synchronization.
                        $operations[] = array(
                                'op' => 'copy',
                                'src' => $dstPath,
                                'dst' => $archivePath,
                                'ignoreMissingSource' => true
                        );

                        // Copy (or move) the source file to the destination
                        if ( FileBackend::isStoragePath( $srcPath ) ) {
                                if ( $flags & self::DELETE_SOURCE ) {
                                        $operations[] = array(
                                                'op' => 'move',
                                                'src' => $srcPath,
                                                'dst' => $dstPath,
                                                'overwrite' => true, // replace current
                                                'headers' => $headers
                                        );
                                } else {
                                        $operations[] = array(
                                                'op' => 'copy',
                                                'src' => $srcPath,
                                                'dst' => $dstPath,
                                                'overwrite' => true, // replace current
                                                'headers' => $headers
                                        );
                                }
                        } else { // FS source path
                                $operations[] = array(
                                        'op' => 'store',
                                        'src' => $srcPath,
                                        'dst' => $dstPath,
                                        'overwrite' => true, // replace current
                                        'headers' => $headers
                                );
                                if ( $flags & self::DELETE_SOURCE ) {
                                        $sourceFSFilesToDelete[] = $srcPath;
                                }
                        }
                }

                // Execute the operations for each triplet
                $status->merge( $backend->doOperations( $operations ) );
                // Find out which files were archived...
                foreach ( $ntuples as $i => $ntuple ) {
                        list( , , $archiveRel ) = $ntuple;
                        $archivePath = $this->getZonePath( 'public' ) . "/$archiveRel";
                        if ( $this->fileExists( $archivePath ) ) {
                                $status->value[$i] = 'archived';
                        } else {
                                $status->value[$i] = 'new';
                        }
                }
                // Cleanup for disk source files...
                foreach ( $sourceFSFilesToDelete as $file ) {
                        MediaWiki\suppressWarnings();
                        unlink( $file ); // FS cleanup
                        MediaWiki\restoreWarnings();
                }

                return $status;
        }

        /**
         * Creates a directory with the appropriate zone permissions.
         * Callers are responsible for doing read-only and "writable repo" checks.
         *
         * @param string $dir Virtual URL (or storage path) of directory to clean
         * @return Status
         */
        protected function initDirectory( $dir ) {
                $path = $this->resolveToStoragePath( $dir );
                list( , $container, ) = FileBackend::splitStoragePath( $path );

                $params = array( 'dir' => $path );
                if ( $this->isPrivate
                        || $container === $this->zones['deleted']['container']
                        || $container === $this->zones['temp']['container']
                ) {
                        # Take all available measures to prevent web accessibility of new deleted
                        # directories, in case the user has not configured offline storage
                        $params = array( 'noAccess' => true, 'noListing' => true ) + $params;
                }

                return $this->backend->prepare( $params );
        }

        /**
         * Deletes a directory if empty.
         *
         * @param string $dir Virtual URL (or storage path) of directory to clean
         * @return Status
         */
        public function cleanDir( $dir ) {
                $this->assertWritableRepo(); // fail out if read-only

                $status = $this->newGood();
                $status->merge( $this->backend->clean(
                        array( 'dir' => $this->resolveToStoragePath( $dir ) ) ) );

                return $status;
        }

        /**
         * Checks existence of a a file
         *
         * @param string $file Virtual URL (or storage path) of file to check
         * @return bool
         */
        public function fileExists( $file ) {
                $result = $this->fileExistsBatch( array( $file ) );

                return $result[0];
        }

        /**
         * Checks existence of an array of files.
         *
         * @param array $files Virtual URLs (or storage paths) of files to check
         * @return array Map of files and existence flags, or false
         */
        public function fileExistsBatch( array $files ) {
                $paths = array_map( array( $this, 'resolveToStoragePath' ), $files );
                $this->backend->preloadFileStat( array( 'srcs' => $paths ) );

                $result = array();
                foreach ( $files as $key => $file ) {
                        $path = $this->resolveToStoragePath( $file );
                        $result[$key] = $this->backend->fileExists( array( 'src' => $path ) );
                }

                return $result;
        }

        /**
         * Move a file to the deletion archive.
         * If no valid deletion archive exists, this may either delete the file
         * or throw an exception, depending on the preference of the repository
         *
         * @param mixed $srcRel Relative path for the file to be deleted
         * @param mixed $archiveRel Relative path for the archive location.
         *   Relative to a private archive directory.
         * @return FileRepoStatus
         */
        public function delete( $srcRel, $archiveRel ) {
                $this->assertWritableRepo(); // fail out if read-only

                return $this->deleteBatch( array( array( $srcRel, $archiveRel ) ) );
        }

        /**
         * Move a group of files to the deletion archive.
         *
         * If no valid deletion archive is configured, this may either delete the
         * file or throw an exception, depending on the preference of the repository.
         *
         * The overwrite policy is determined by the repository -- currently LocalRepo
         * assumes a naming scheme in the deleted zone based on content hash, as
         * opposed to the public zone which is assumed to be unique.
         *
         * @param array $sourceDestPairs Array of source/destination pairs. Each element
         *   is a two-element array containing the source file path relative to the
         *   public root in the first element, and the archive file path relative
         *   to the deleted zone root in the second element.
         * @throws MWException
         * @return FileRepoStatus
         */
        public function deleteBatch( array $sourceDestPairs ) {
                $this->assertWritableRepo(); // fail out if read-only

                // Try creating directories
                $status = $this->initZones( array( 'public', 'deleted' ) );
                if ( !$status->isOK() ) {
                        return $status;
                }

                $status = $this->newGood();

                $backend = $this->backend; // convenience
                $operations = array();
                // Validate filenames and create archive directories
                foreach ( $sourceDestPairs as $pair ) {
                        list( $srcRel, $archiveRel ) = $pair;
                        if ( !$this->validateFilename( $srcRel ) ) {
                                throw new MWException( __METHOD__ . ':Validation error in $srcRel' );
                        } elseif ( !$this->validateFilename( $archiveRel ) ) {
                                throw new MWException( __METHOD__ . ':Validation error in $archiveRel' );
                        }

                        $publicRoot = $this->getZonePath( 'public' );
                        $srcPath = "{$publicRoot}/$srcRel";

                        $deletedRoot = $this->getZonePath( 'deleted' );
                        $archivePath = "{$deletedRoot}/{$archiveRel}";
                        $archiveDir = dirname( $archivePath ); // does not touch FS

                        // Create destination directories
                        if ( !$this->initDirectory( $archiveDir )->isOK() ) {
                                return $this->newFatal( 'directorycreateerror', $archiveDir );
                        }

                        $operations[] = array(
                                'op' => 'move',
                                'src' => $srcPath,
                                'dst' => $archivePath,
                                // We may have 2+ identical files being deleted,
                                // all of which will map to the same destination file
                                'overwriteSame' => true // also see bug 31792
                        );
                }

                // Move the files by execute the operations for each pair.
                // We're now committed to returning an OK result, which will
                // lead to the files being moved in the DB also.
                $opts = array( 'force' => true );
                $status->merge( $backend->doOperations( $operations, $opts ) );

                return $status;
        }

        /**
         * Delete files in the deleted directory if they are not referenced in the filearchive table
         *
         * STUB
         * @param array $storageKeys
         */
        public function cleanupDeletedBatch( array $storageKeys ) {
                $this->assertWritableRepo();
        }

        /**
         * Get a relative path for a deletion archive key,
         * e.g. s/z/a/ for sza251lrxrc1jad41h5mgilp8nysje52.jpg
         *
         * @param string $key
         * @throws MWException
         * @return string
         */
        public function getDeletedHashPath( $key ) {
                if ( strlen( $key ) < 31 ) {
                        throw new MWException( "Invalid storage key '$key'." );
                }
                $path = '';
                for ( $i = 0; $i < $this->deletedHashLevels; $i++ ) {
                        $path .= $key[$i] . '/';
                }

                return $path;
        }

        /**
         * If a path is a virtual URL, resolve it to a storage path.
         * Otherwise, just return the path as it is.
         *
         * @param string $path
         * @return string
         * @throws MWException
         */
        protected function resolveToStoragePath( $path ) {
                if ( $this->isVirtualUrl( $path ) ) {
                        return $this->resolveVirtualUrl( $path );
                }

                return $path;
        }

        /**
         * Get a local FS copy of a file with a given virtual URL/storage path.
         * Temporary files may be purged when the file object falls out of scope.
         *
         * @param string $virtualUrl
         * @return TempFSFile|null Returns null on failure
         */
        public function getLocalCopy( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getLocalCopy( array( 'src' => $path ) );
        }

        /**
         * Get a local FS file with a given virtual URL/storage path.
         * The file is either an original or a copy. It should not be changed.
         * Temporary files may be purged when the file object falls out of scope.
         *
         * @param string $virtualUrl
         * @return FSFile|null Returns null on failure.
         */
        public function getLocalReference( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getLocalReference( array( 'src' => $path ) );
        }

        /**
         * Get properties of a file with a given virtual URL/storage path.
         * Properties should ultimately be obtained via FSFile::getProps().
         *
         * @param string $virtualUrl
         * @return array
         */
        public function getFileProps( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getFileProps( array( 'src' => $path ) );
        }

        /**
         * Get the timestamp of a file with a given virtual URL/storage path
         *
         * @param string $virtualUrl
         * @return string|bool False on failure
         */
        public function getFileTimestamp( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getFileTimestamp( array( 'src' => $path ) );
        }

        /**
         * Get the size of a file with a given virtual URL/storage path
         *
         * @param string $virtualUrl
         * @return int|bool False on failure
         */
        public function getFileSize( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getFileSize( array( 'src' => $path ) );
        }

        /**
         * Get the sha1 (base 36) of a file with a given virtual URL/storage path
         *
         * @param string $virtualUrl
         * @return string|bool
         */
        public function getFileSha1( $virtualUrl ) {
                $path = $this->resolveToStoragePath( $virtualUrl );

                return $this->backend->getFileSha1Base36( array( 'src' => $path ) );
        }

        /**
         * Attempt to stream a file with the given virtual URL/storage path
         *
         * @param string $virtualUrl
         * @param array $headers Additional HTTP headers to send on success
         * @return Status
         * @since 1.27
         */
        public function streamFileWithStatus( $virtualUrl, $headers = array() ) {
                $path = $this->resolveToStoragePath( $virtualUrl );
                $params = array( 'src' => $path, 'headers' => $headers );

                return $this->backend->streamFile( $params );
        }

        /**
         * Attempt to stream a file with the given virtual URL/storage path
         *
         * @deprecated since 1.26, use streamFileWithStatus
         * @param string $virtualUrl
         * @param array $headers Additional HTTP headers to send on success
         * @return bool Success
         */
        public function streamFile( $virtualUrl, $headers = array() ) {
                return $this->streamFileWithStatus( $virtualUrl, $headers )->isOK();
        }

        /**
         * Call a callback function for every public regular file in the repository.
         * This only acts on the current version of files, not any old versions.
         * May use either the database or the filesystem.
         *
         * @param callable $callback
         * @return void
         */
        public function enumFiles( $callback ) {
                $this->enumFilesInStorage( $callback );
        }

        /**
         * Call a callback function for every public file in the repository.
         * May use either the database or the filesystem.
         *
         * @param callable $callback
         * @return void
         */
        protected function enumFilesInStorage( $callback ) {
                $publicRoot = $this->getZonePath( 'public' );
                $numDirs = 1 << ( $this->hashLevels * 4 );
                // Use a priori assumptions about directory structure
                // to reduce the tree height of the scanning process.
                for ( $flatIndex = 0; $flatIndex < $numDirs; $flatIndex++ ) {
                        $hexString = sprintf( "%0{$this->hashLevels}x", $flatIndex );
                        $path = $publicRoot;
                        for ( $hexPos = 0; $hexPos < $this->hashLevels; $hexPos++ ) {
                                $path .= '/' . substr( $hexString, 0, $hexPos + 1 );
                        }
                        $iterator = $this->backend->getFileList( array( 'dir' => $path ) );
                        foreach ( $iterator as $name ) {
                                // Each item returned is a public file
                                call_user_func( $callback, "{$path}/{$name}" );
                        }
                }
        }

        /**
         * Determine if a relative path is valid, i.e. not blank or involving directory traveral
         *
         * @param string $filename
         * @return bool
         */
        public function validateFilename( $filename ) {
                if ( strval( $filename ) == '' ) {
                        return false;
                }

                return FileBackend::isPathTraversalFree( $filename );
        }

        /**
         * Get a callback function to use for cleaning error message parameters
         *
         * @return array
         */
        function getErrorCleanupFunction() {
                switch ( $this->pathDisclosureProtection ) {
                        case 'none':
                        case 'simple': // b/c
                                $callback = array( $this, 'passThrough' );
                                break;
                        default: // 'paranoid'
                                $callback = array( $this, 'paranoidClean' );
                }
                return $callback;
        }

        /**
         * Path disclosure protection function
         *
         * @param string $param
         * @return string
         */
        function paranoidClean( $param ) {
                return '[hidden]';
        }

        /**
         * Path disclosure protection function
         *
         * @param string $param
         * @return string
         */
        function passThrough( $param ) {
                return $param;
        }

        /**
         * Create a new fatal error
         *
         * @param string $message
         * @return Status
         */
        public function newFatal( $message /*, parameters...*/ ) {
                $status = call_user_func_array( array( 'Status', 'newFatal' ), func_get_args() );
                $status->cleanCallback = $this->getErrorCleanupFunction();

                return $status;
        }

        /**
         * Create a new good result
         *
         * @param null|string $value
         * @return Status
         */
        public function newGood( $value = null ) {
                $status = Status::newGood( $value );
                $status->cleanCallback = $this->getErrorCleanupFunction();

                return $status;
        }

        /**
         * Checks if there is a redirect named as $title. If there is, return the
         * title object. If not, return false.
         * STUB
         *
         * @param Title $title Title of image
         * @return bool
         */
        public function checkRedirect( Title $title ) {
                return false;
        }

        /**
         * Invalidates image redirect cache related to that image
         * Doesn't do anything for repositories that don't support image redirects.
         *
         * STUB
         * @param Title $title Title of image
         */
        public function invalidateImageRedirect( Title $title ) {
        }

        /**
         * Get the human-readable name of the repo
         *
         * @return string
         */
        public function getDisplayName() {
                global $wgSitename;

                if ( $this->isLocal() ) {
                        return $wgSitename;
                }

                // 'shared-repo-name-wikimediacommons' is used when $wgUseInstantCommons = true
                return wfMessageFallback( 'shared-repo-name-' . $this->name, 'shared-repo' )->text();
        }

        /**
         * Get the portion of the file that contains the origin file name.
         * If that name is too long, then the name "thumbnail.<ext>" will be given.
         *
         * @param string $name
         * @return string
         */
        public function nameForThumb( $name ) {
                if ( strlen( $name ) > $this->abbrvThreshold ) {
                        $ext = FileBackend::extensionFromPath( $name );
                        $name = ( $ext == '' ) ? 'thumbnail' : "thumbnail.$ext";
                }

                return $name;
        }

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

        /**
         * Get a key on the primary cache for this repository.
         * Returns false if the repository's cache is not accessible at this site.
         * The parameters are the parts of the key, as for wfMemcKey().
         *
         * STUB
         * @return bool
         */
        public function getSharedCacheKey( /*...*/ ) {
                return false;
        }

        /**
         * Get a key for this repo in the local cache domain. These cache keys are
         * not shared with remote instances of the repo.
         * The parameters are the parts of the key, as for wfMemcKey().
         *
         * @return string
         */
        public function getLocalCacheKey( /*...*/ ) {
                $args = func_get_args();
                array_unshift( $args, 'filerepo', $this->getName() );

                return call_user_func_array( 'wfMemcKey', $args );
        }

        /**
         * Get a temporary private FileRepo associated with this repo.
         *
         * Files will be created in the temp zone of this repo.
         * It will have the same backend as this repo.
         *
         * @return TempFileRepo
         */
        public function getTempRepo() {
                return new TempFileRepo( array(
                        'name' => "{$this->name}-temp",
                        'backend' => $this->backend,
                        'zones' => array(
                                'public' => array(
                                        // Same place storeTemp() uses in the base repo, though
                                        // the path hashing is mismatched, which is annoying.
                                        'container' => $this->zones['temp']['container'],
                                        'directory' => $this->zones['temp']['directory']
                                ),
                                'thumb' => array(
                                        'container' => $this->zones['temp']['container'],
                                        'directory' => $this->zones['temp']['directory'] == ''
                                                ? 'thumb'
                                                : $this->zones['temp']['directory'] . '/thumb'
                                ),
                                'transcoded' => array(
                                        'container' => $this->zones['temp']['container'],
                                        'directory' => $this->zones['temp']['directory'] == ''
                                                ? 'transcoded'
                                                : $this->zones['temp']['directory'] . '/transcoded'
                                )
                        ),
                        'hashLevels' => $this->hashLevels, // performance
                        'isPrivate' => true // all in temp zone
                ) );
        }

        /**
         * Get an UploadStash associated with this repo.
         *
         * @param User $user
         * @return UploadStash
         */
        public function getUploadStash( User $user = null ) {
                return new UploadStash( $this, $user );
        }

        /**
         * Throw an exception if this repo is read-only by design.
         * This does not and should not check getReadOnlyReason().
         *
         * @return void
         * @throws MWException
         */
        protected function assertWritableRepo() {
        }

        /**
         * Return information about the repository.
         *
         * @return array
         * @since 1.22
         */
        public function getInfo() {
                $ret = array(
                        'name' => $this->getName(),
                        'displayname' => $this->getDisplayName(),
                        'rootUrl' => $this->getZoneUrl( 'public' ),
                        'local' => $this->isLocal(),
                );

                $optionalSettings = array(
                        'url', 'thumbUrl', 'initialCapital', 'descBaseUrl', 'scriptDirUrl', 'articleUrl',
                        'fetchDescription', 'descriptionCacheExpiry', 'scriptExtension', 'favicon'
                );
                foreach ( $optionalSettings as $k ) {
                        if ( isset( $this->$k ) ) {
                                $ret[$k] = $this->$k;
                        }
                }

                return $ret;
        }

        /**
         * Returns whether or not storage is SHA-1 based
         * @return boolean
         */
        public function hasSha1Storage() {
                return $this->hasSha1Storage;
        }

        /**
         * Returns whether or not repo supports having originals SHA-1s in the thumb URLs
         * @return boolean
         */
        public function supportsSha1URLs() {
                return $this->supportsSha1URLs;
        }
}

/**
 * FileRepo for temporary files created via FileRepo::getTempRepo()
 */
class TempFileRepo extends FileRepo {
        public function getTempRepo() {
                throw new MWException( "Cannot get a temp repo from a temp repo." );
        }
}