Made SwiftFileBackend::loadObjectListing() populate stat entries in reverse order.

[lhc/web/wiklou.git] / includes / filebackend / SwiftFileBackend.php

<?php
/**
 * OpenStack Swift based file backend.
 *
 * 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 FileBackend
 * @author Russ Nelson
 * @author Aaron Schulz
 */

/**
 * @brief Class for an OpenStack Swift based file backend.
 *
 * This requires the SwiftCloudFiles MediaWiki extension, which includes
 * the php-cloudfiles library (https://github.com/rackspace/php-cloudfiles).
 * php-cloudfiles requires the curl, fileinfo, and mb_string PHP extensions.
 *
 * Status messages should avoid mentioning the Swift account name.
 * Likewise, error suppression should be used to avoid path disclosure.
 *
 * @ingroup FileBackend
 * @since 1.19
 */
class SwiftFileBackend extends FileBackendStore {
        /** @var CF_Authentication */
        protected $auth; // Swift authentication handler
        protected $authTTL; // integer seconds
        protected $swiftTempUrlKey; // string; shared secret value for making temp urls
        protected $swiftAnonUser; // string; username to handle unauthenticated requests
        protected $swiftUseCDN; // boolean; whether CloudFiles CDN is enabled
        protected $swiftCDNExpiry; // integer; how long to cache things in the CDN
        protected $swiftCDNPurgable; // boolean; whether object CDN purging is enabled

        // Rados Gateway specific options
        protected $rgwS3AccessKey; // string; S3 access key
        protected $rgwS3SecretKey; // string; S3 authentication key

        /** @var CF_Connection */
        protected $conn; // Swift connection handle
        protected $sessionStarted = 0; // integer UNIX timestamp

        /** @var CloudFilesException */
        protected $connException;
        protected $connErrorTime = 0; // UNIX timestamp

        /** @var BagOStuff */
        protected $srvCache;

        /** @var ProcessCacheLRU */
        protected $connContainerCache; // container object cache

        /**
         * @see FileBackendStore::__construct()
         * Additional $config params include:
         *   - swiftAuthUrl       : Swift authentication server URL
         *   - swiftUser          : Swift user used by MediaWiki (account:username)
         *   - swiftKey           : Swift authentication key for the above user
         *   - swiftAuthTTL       : Swift authentication TTL (seconds)
         *   - swiftTempUrlKey    : Swift "X-Account-Meta-Temp-URL-Key" value on the account.
         *                          Do not set this until it has been set in the backend.
         *   - swiftAnonUser      : Swift user used for end-user requests (account:username).
         *                          If set, then views of public containers are assumed to go
         *                          through this user. If not set, then public containers are
         *                          accessible to unauthenticated requests via ".r:*" in the ACL.
         *   - swiftUseCDN        : Whether a Cloud Files Content Delivery Network is set up
         *   - swiftCDNExpiry     : How long (in seconds) to store content in the CDN.
         *                          If files may likely change, this should probably not exceed
         *                          a few days. For example, deletions may take this long to apply.
         *                          If object purging is enabled, however, this is not an issue.
         *   - swiftCDNPurgable   : Whether object purge requests are allowed by the CDN.
         *   - shardViaHashLevels : Map of container names to sharding config with:
         *                             - base   : base of hash characters, 16 or 36
         *                             - levels : the number of hash levels (and digits)
         *                             - repeat : hash subdirectories are prefixed with all the
         *                                        parent hash directory names (e.g. "a/ab/abc")
         *   - cacheAuthInfo      : Whether to cache authentication tokens in APC, XCache, ect.
         *                          If those are not available, then the main cache will be used.
         *                          This is probably insecure in shared hosting environments.
         *   - rgwS3AccessKey     : Ragos Gateway S3 "access key" value on the account.
         *                          Do not set this until it has been set in the backend.
         *                          This is used for generating expiring pre-authenticated URLs.
         *                          Only use this when using rgw and to work around
         *                          http://tracker.newdream.net/issues/3454.
         *   - rgwS3SecretKey     : Ragos Gateway S3 "secret key" value on the account.
         *                          Do not set this until it has been set in the backend.
         *                          This is used for generating expiring pre-authenticated URLs.
         *                          Only use this when using rgw and to work around
         *                          http://tracker.newdream.net/issues/3454.
         */
        public function __construct( array $config ) {
                parent::__construct( $config );
                if ( !class_exists( 'CF_Constants' ) ) {
                        throw new MWException( 'SwiftCloudFiles extension not installed.' );
                }
                // Required settings
                $this->auth = new CF_Authentication(
                        $config['swiftUser'],
                        $config['swiftKey'],
                        null, // account; unused
                        $config['swiftAuthUrl']
                );
                // Optional settings
                $this->authTTL = isset( $config['swiftAuthTTL'] )
                        ? $config['swiftAuthTTL']
                        : 5 * 60; // some sane number
                $this->swiftAnonUser = isset( $config['swiftAnonUser'] )
                        ? $config['swiftAnonUser']
                        : '';
                $this->swiftTempUrlKey = isset( $config['swiftTempUrlKey'] )
                        ? $config['swiftTempUrlKey']
                        : '';
                $this->shardViaHashLevels = isset( $config['shardViaHashLevels'] )
                        ? $config['shardViaHashLevels']
                        : '';
                $this->swiftUseCDN = isset( $config['swiftUseCDN'] )
                        ? $config['swiftUseCDN']
                        : false;
                $this->swiftCDNExpiry = isset( $config['swiftCDNExpiry'] )
                        ? $config['swiftCDNExpiry']
                        : 12 * 3600; // 12 hours is safe (tokens last 24 hours per http://docs.openstack.org)
                $this->swiftCDNPurgable = isset( $config['swiftCDNPurgable'] )
                        ? $config['swiftCDNPurgable']
                        : true;
                $this->rgwS3AccessKey = isset( $config['rgwS3AccessKey'] )
                        ? $config['rgwS3AccessKey']
                        : '';
                $this->rgwS3SecretKey = isset( $config['rgwS3SecretKey'] )
                        ? $config['rgwS3SecretKey']
                        : '';
                // Cache container information to mask latency
                $this->memCache = wfGetMainCache();
                // Process cache for container info
                $this->connContainerCache = new ProcessCacheLRU( 300 );
                // Cache auth token information to avoid RTTs
                if ( !empty( $config['cacheAuthInfo'] ) ) {
                        if ( PHP_SAPI === 'cli' ) {
                                $this->srvCache = wfGetMainCache(); // preferrably memcached
                        } else {
                                try { // look for APC, XCache, WinCache, ect...
                                        $this->srvCache = ObjectCache::newAccelerator( array() );
                                } catch ( Exception $e ) {}
                        }
                }
                $this->srvCache = $this->srvCache ? $this->srvCache : new EmptyBagOStuff();
        }

        /**
         * @see FileBackendStore::resolveContainerPath()
         * @return null
         */
        protected function resolveContainerPath( $container, $relStoragePath ) {
                if ( !mb_check_encoding( $relStoragePath, 'UTF-8' ) ) { // mb_string required by CF
                        return null; // not UTF-8, makes it hard to use CF and the swift HTTP API
                } elseif ( strlen( urlencode( $relStoragePath ) ) > 1024 ) {
                        return null; // too long for Swift
                }
                return $relStoragePath;
        }

        /**
         * @see FileBackendStore::isPathUsableInternal()
         * @return bool
         */
        public function isPathUsableInternal( $storagePath ) {
                list( $container, $rel ) = $this->resolveStoragePathReal( $storagePath );
                if ( $rel === null ) {
                        return false; // invalid
                }

                try {
                        $this->getContainer( $container );
                        return true; // container exists
                } catch ( NoSuchContainerException $e ) {
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, null, __METHOD__, array( 'path' => $storagePath ) );
                }

                return false;
        }

        /**
         * @param $headers array
         * @return array
         */
        protected function sanitizeHdrs( array $headers ) {
                // By default, Swift has annoyingly low maximum header value limits
                if ( isset( $headers['Content-Disposition'] ) ) {
                        $headers['Content-Disposition'] = $this->truncDisp( $headers['Content-Disposition'] );
                }
                return $headers;
        }

        /**
         * @param $disposition string Content-Disposition header value
         * @return string Truncated Content-Disposition header value to meet Swift limits
         */
        protected function truncDisp( $disposition ) {
                $res = '';
                foreach ( explode( ';', $disposition ) as $part ) {
                        $part = trim( $part );
                        $new = ( $res === '' ) ? $part : "{$res};{$part}";
                        if ( strlen( $new ) <= 255 ) {
                                $res = $new;
                        } else {
                                break; // too long; sigh
                        }
                }
                return $res;
        }

        /**
         * @see FileBackendStore::doCreateInternal()
         * @return Status
         */
        protected function doCreateInternal( array $params ) {
                $status = Status::newGood();

                list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
                if ( $dstRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
                        return $status;
                }

                // (a) Check the destination container and object
                try {
                        $dContObj = $this->getContainer( $dstCont );
                } catch ( NoSuchContainerException $e ) {
                        $status->fatal( 'backend-fail-create', $params['dst'] );
                        return $status;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Get a SHA-1 hash of the object
                $sha1Hash = wfBaseConvert( sha1( $params['content'] ), 16, 36, 31 );

                // (c) Actually create the object
                try {
                        // Create a fresh CF_Object with no fields preloaded.
                        // We don't want to preserve headers, metadata, and such.
                        $obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
                        $obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
                        // Manually set the ETag (https://github.com/rackspace/php-cloudfiles/issues/59).
                        // The MD5 here will be checked within Swift against its own MD5.
                        $obj->set_etag( md5( $params['content'] ) );
                        // Use the same content type as StreamFile for security
                        $obj->content_type = StreamFile::contentTypeFromPath( $params['dst'] );
                        if ( !strlen( $obj->content_type ) ) { // special case
                                $obj->content_type = 'unknown/unknown';
                        }
                        // Set any other custom headers if requested
                        if ( isset( $params['headers'] ) ) {
                                $obj->headers += $this->sanitizeHdrs( $params['headers'] );
                        }
                        if ( !empty( $params['async'] ) ) { // deferred
                                $op = $obj->write_async( $params['content'] );
                                $status->value = new SwiftFileOpHandle( $this, $params, 'Create', $op );
                                $status->value->affectedObjects[] = $obj;
                        } else { // actually write the object in Swift
                                $obj->write( $params['content'] );
                                $this->purgeCDNCache( array( $obj ) );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( BadContentTypeException $e ) {
                        $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see SwiftFileBackend::doExecuteOpHandlesInternal()
         */
        protected function _getResponseCreate( CF_Async_Op $cfOp, Status $status, array $params ) {
                try {
                        $cfOp->getLastResponse();
                } catch ( BadContentTypeException $e ) {
                        $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                }
        }

        /**
         * @see FileBackendStore::doStoreInternal()
         * @return Status
         */
        protected function doStoreInternal( array $params ) {
                $status = Status::newGood();

                list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
                if ( $dstRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
                        return $status;
                }

                // (a) Check the destination container and object
                try {
                        $dContObj = $this->getContainer( $dstCont );
                } catch ( NoSuchContainerException $e ) {
                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                        return $status;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Get a SHA-1 hash of the object
                wfSuppressWarnings();
                $sha1Hash = sha1_file( $params['src'] );
                wfRestoreWarnings();
                if ( $sha1Hash === false ) { // source doesn't exist?
                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                        return $status;
                }
                $sha1Hash = wfBaseConvert( $sha1Hash, 16, 36, 31 );

                // (c) Actually store the object
                try {
                        // Create a fresh CF_Object with no fields preloaded.
                        // We don't want to preserve headers, metadata, and such.
                        $obj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
                        $obj->setMetadataValues( array( 'Sha1base36' => $sha1Hash ) );
                        // The MD5 here will be checked within Swift against its own MD5.
                        $obj->set_etag( md5_file( $params['src'] ) );
                        // Use the same content type as StreamFile for security
                        $obj->content_type = StreamFile::contentTypeFromPath( $params['dst'] );
                        if ( !strlen( $obj->content_type ) ) { // special case
                                $obj->content_type = 'unknown/unknown';
                        }
                        // Set any other custom headers if requested
                        if ( isset( $params['headers'] ) ) {
                                $obj->headers += $this->sanitizeHdrs( $params['headers'] );
                        }
                        if ( !empty( $params['async'] ) ) { // deferred
                                wfSuppressWarnings();
                                $fp = fopen( $params['src'], 'rb' );
                                wfRestoreWarnings();
                                if ( !$fp ) {
                                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                                } else {
                                        $op = $obj->write_async( $fp, filesize( $params['src'] ), true );
                                        $status->value = new SwiftFileOpHandle( $this, $params, 'Store', $op );
                                        $status->value->resourcesToClose[] = $fp;
                                        $status->value->affectedObjects[] = $obj;
                                }
                        } else { // actually write the object in Swift
                                $obj->load_from_filename( $params['src'], true ); // calls $obj->write()
                                $this->purgeCDNCache( array( $obj ) );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( BadContentTypeException $e ) {
                        $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                } catch ( IOException $e ) {
                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see SwiftFileBackend::doExecuteOpHandlesInternal()
         */
        protected function _getResponseStore( CF_Async_Op $cfOp, Status $status, array $params ) {
                try {
                        $cfOp->getLastResponse();
                } catch ( BadContentTypeException $e ) {
                        $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                } catch ( IOException $e ) {
                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                }
        }

        /**
         * @see FileBackendStore::doCopyInternal()
         * @return Status
         */
        protected function doCopyInternal( array $params ) {
                $status = Status::newGood();

                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['src'] );
                        return $status;
                }

                list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
                if ( $dstRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
                        return $status;
                }

                // (a) Check the source/destination containers and destination object
                try {
                        $sContObj = $this->getContainer( $srcCont );
                        $dContObj = $this->getContainer( $dstCont );
                } catch ( NoSuchContainerException $e ) {
                        if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
                                $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                        }
                        return $status;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Actually copy the file to the destination
                try {
                        $dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
                        $hdrs = array(); // source file headers to override with new values
                        // Set any other custom headers if requested
                        if ( isset( $params['headers'] ) ) {
                                $hdrs += $this->sanitizeHdrs( $params['headers'] );
                        }
                        if ( !empty( $params['async'] ) ) { // deferred
                                $op = $sContObj->copy_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
                                $status->value = new SwiftFileOpHandle( $this, $params, 'Copy', $op );
                                $status->value->affectedObjects[] = $dstObj;
                        } else { // actually write the object in Swift
                                $sContObj->copy_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
                                $this->purgeCDNCache( array( $dstObj ) );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( NoSuchObjectException $e ) { // source object does not exist
                        if ( empty( $params['ignoreMissingSource'] ) ) {
                                $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                        }
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see SwiftFileBackend::doExecuteOpHandlesInternal()
         */
        protected function _getResponseCopy( CF_Async_Op $cfOp, Status $status, array $params ) {
                try {
                        $cfOp->getLastResponse();
                } catch ( NoSuchObjectException $e ) { // source object does not exist
                        $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                }
        }

        /**
         * @see FileBackendStore::doMoveInternal()
         * @return Status
         */
        protected function doMoveInternal( array $params ) {
                $status = Status::newGood();

                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['src'] );
                        return $status;
                }

                list( $dstCont, $dstRel ) = $this->resolveStoragePathReal( $params['dst'] );
                if ( $dstRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['dst'] );
                        return $status;
                }

                // (a) Check the source/destination containers and destination object
                try {
                        $sContObj = $this->getContainer( $srcCont );
                        $dContObj = $this->getContainer( $dstCont );
                } catch ( NoSuchContainerException $e ) {
                        if ( empty( $params['ignoreMissingSource'] ) || isset( $sContObj ) ) {
                                $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
                        }
                        return $status;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Actually move the file to the destination
                try {
                        $srcObj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                        $dstObj = new CF_Object( $dContObj, $dstRel, false, false ); // skip HEAD
                        $hdrs = array(); // source file headers to override with new values
                        // Set any other custom headers if requested
                        if ( isset( $params['headers'] ) ) {
                                $hdrs += $this->sanitizeHdrs( $params['headers'] );
                        }
                        if ( !empty( $params['async'] ) ) { // deferred
                                $op = $sContObj->move_object_to_async( $srcRel, $dContObj, $dstRel, null, $hdrs );
                                $status->value = new SwiftFileOpHandle( $this, $params, 'Move', $op );
                                $status->value->affectedObjects[] = $srcObj;
                                $status->value->affectedObjects[] = $dstObj;
                        } else { // actually write the object in Swift
                                $sContObj->move_object_to( $srcRel, $dContObj, $dstRel, null, $hdrs );
                                $this->purgeCDNCache( array( $srcObj ) );
                                $this->purgeCDNCache( array( $dstObj ) );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( NoSuchObjectException $e ) { // source object does not exist
                        if ( empty( $params['ignoreMissingSource'] ) ) {
                                $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
                        }
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see SwiftFileBackend::doExecuteOpHandlesInternal()
         */
        protected function _getResponseMove( CF_Async_Op $cfOp, Status $status, array $params ) {
                try {
                        $cfOp->getLastResponse();
                } catch ( NoSuchObjectException $e ) { // source object does not exist
                        $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
                }
        }

        /**
         * @see FileBackendStore::doDeleteInternal()
         * @return Status
         */
        protected function doDeleteInternal( array $params ) {
                $status = Status::newGood();

                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['src'] );
                        return $status;
                }

                try {
                        $sContObj = $this->getContainer( $srcCont );
                        $srcObj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                        if ( !empty( $params['async'] ) ) { // deferred
                                $op = $sContObj->delete_object_async( $srcRel );
                                $status->value = new SwiftFileOpHandle( $this, $params, 'Delete', $op );
                                $status->value->affectedObjects[] = $srcObj;
                        } else { // actually write the object in Swift
                                $sContObj->delete_object( $srcRel );
                                $this->purgeCDNCache( array( $srcObj ) );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( NoSuchContainerException $e ) {
                        if ( empty( $params['ignoreMissingSource'] ) ) {
                                $status->fatal( 'backend-fail-delete', $params['src'] );
                        }
                } catch ( NoSuchObjectException $e ) {
                        if ( empty( $params['ignoreMissingSource'] ) ) {
                                $status->fatal( 'backend-fail-delete', $params['src'] );
                        }
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see SwiftFileBackend::doExecuteOpHandlesInternal()
         */
        protected function _getResponseDelete( CF_Async_Op $cfOp, Status $status, array $params ) {
                try {
                        $cfOp->getLastResponse();
                } catch ( NoSuchContainerException $e ) {
                        $status->fatal( 'backend-fail-delete', $params['src'] );
                } catch ( NoSuchObjectException $e ) {
                        if ( empty( $params['ignoreMissingSource'] ) ) {
                                $status->fatal( 'backend-fail-delete', $params['src'] );
                        }
                }
        }

        /**
         * @see FileBackendStore::doDescribeInternal()
         * @return Status
         */
        protected function doDescribeInternal( array $params ) {
                $status = Status::newGood();

                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['src'] );
                        return $status;
                }

                try {
                        $sContObj = $this->getContainer( $srcCont );
                        // Get the latest version of the current metadata
                        $srcObj = $sContObj->get_object( $srcRel,
                                $this->headersFromParams( array( 'latest' => true ) ) );
                        // Merge in the metadata updates...
                        if ( isset( $params['headers'] ) ) {
                                $srcObj->headers = $this->sanitizeHdrs( $params['headers'] ) + $srcObj->headers;
                        }
                        $srcObj->sync_metadata(); // save to Swift
                        $this->purgeCDNCache( array( $srcObj ) );
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( NoSuchContainerException $e ) {
                        $status->fatal( 'backend-fail-describe', $params['src'] );
                } catch ( NoSuchObjectException $e ) {
                        $status->fatal( 'backend-fail-describe', $params['src'] );
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doPrepareInternal()
         * @return Status
         */
        protected function doPrepareInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();

                // (a) Check if container already exists
                try {
                        $this->getContainer( $fullCont );
                        // NoSuchContainerException not thrown: container must exist
                        return $status; // already exists
                } catch ( NoSuchContainerException $e ) {
                        // NoSuchContainerException thrown: container does not exist
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Create container as needed
                try {
                        $contObj = $this->createContainer( $fullCont );
                        if ( !empty( $params['noAccess'] ) ) {
                                // Make container private to end-users...
                                $status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) );
                        } else {
                                // Make container public to end-users...
                                $status->merge( $this->doPublishInternal( $fullCont, $dir, $params ) );
                        }
                        if ( $this->swiftUseCDN ) { // Rackspace style CDN
                                $contObj->make_public( $this->swiftCDNExpiry );
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doSecureInternal()
         * @return Status
         */
        protected function doSecureInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();
                if ( empty( $params['noAccess'] ) ) {
                        return $status; // nothing to do
                }

                // Restrict container from end-users...
                try {
                        // doPrepareInternal() should have been called,
                        // so the Swift container should already exist...
                        $contObj = $this->getContainer( $fullCont ); // normally a cache hit
                        // NoSuchContainerException not thrown: container must exist

                        // Make container private to end-users...
                        $status->merge( $this->setContainerAccess(
                                $contObj,
                                array( $this->auth->username ), // read
                                array( $this->auth->username ) // write
                        ) );
                        if ( $this->swiftUseCDN && $contObj->is_public() ) { // Rackspace style CDN
                                $contObj->make_private();
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doPublishInternal()
         * @return Status
         */
        protected function doPublishInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();

                // Unrestrict container from end-users...
                try {
                        // doPrepareInternal() should have been called,
                        // so the Swift container should already exist...
                        $contObj = $this->getContainer( $fullCont ); // normally a cache hit
                        // NoSuchContainerException not thrown: container must exist

                        // Make container public to end-users...
                        if ( $this->swiftAnonUser != '' ) {
                                $status->merge( $this->setContainerAccess(
                                        $contObj,
                                        array( $this->auth->username, $this->swiftAnonUser ), // read
                                        array( $this->auth->username, $this->swiftAnonUser ) // write
                                ) );
                        } else {
                                $status->merge( $this->setContainerAccess(
                                        $contObj,
                                        array( $this->auth->username, '.r:*' ), // read
                                        array( $this->auth->username ) // write
                                ) );
                        }
                        if ( $this->swiftUseCDN && !$contObj->is_public() ) { // Rackspace style CDN
                                $contObj->make_public();
                        }
                } catch ( CDNNotEnabledException $e ) {
                        // CDN not enabled; nothing to see here
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doCleanInternal()
         * @return Status
         */
        protected function doCleanInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();

                // Only containers themselves can be removed, all else is virtual
                if ( $dir != '' ) {
                        return $status; // nothing to do
                }

                // (a) Check the container
                try {
                        $contObj = $this->getContainer( $fullCont, true );
                } catch ( NoSuchContainerException $e ) {
                        return $status; // ok, nothing to do
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                // (b) Delete the container if empty
                if ( $contObj->object_count == 0 ) {
                        try {
                                $this->deleteContainer( $fullCont );
                        } catch ( NoSuchContainerException $e ) {
                                return $status; // race?
                        } catch ( NonEmptyContainerException $e ) {
                                return $status; // race? consistency delay?
                        } catch ( CloudFilesException $e ) { // some other exception?
                                $this->handleException( $e, $status, __METHOD__, $params );
                                return $status;
                        }
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doFileExists()
         * @return array|bool|null
         */
        protected function doGetFileStat( array $params ) {
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        return false; // invalid storage path
                }

                $stat = false;
                try {
                        $contObj = $this->getContainer( $srcCont );
                        $srcObj = $contObj->get_object( $srcRel, $this->headersFromParams( $params ) );
                        $this->addMissingMetadata( $srcObj, $params['src'] );
                        $stat = array(
                                // Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
                                'mtime' => wfTimestamp( TS_MW, $srcObj->last_modified ),
                                'size' => (int)$srcObj->content_length,
                                'sha1' => $srcObj->getMetadataValue( 'Sha1base36' )
                        );
                } catch ( NoSuchContainerException $e ) {
                } catch ( NoSuchObjectException $e ) {
                } catch ( CloudFilesException $e ) { // some other exception?
                        $stat = null;
                        $this->handleException( $e, null, __METHOD__, $params );
                }

                return $stat;
        }

        /**
         * Fill in any missing object metadata and save it to Swift
         *
         * @param $obj CF_Object
         * @param string $path Storage path to object
         * @return bool Success
         * @throws Exception cloudfiles exceptions
         */
        protected function addMissingMetadata( CF_Object $obj, $path ) {
                if ( $obj->getMetadataValue( 'Sha1base36' ) !== null ) {
                        return true; // nothing to do
                }
                wfProfileIn( __METHOD__ );
                trigger_error( "$path was not stored with SHA-1 metadata.", E_USER_WARNING );
                $status = Status::newGood();
                $scopeLockS = $this->getScopedFileLocks( array( $path ), LockManager::LOCK_UW, $status );
                if ( $status->isOK() ) {
                        $tmpFile = $this->getLocalCopy( array( 'src' => $path, 'latest' => 1 ) );
                        if ( $tmpFile ) {
                                $hash = $tmpFile->getSha1Base36();
                                if ( $hash !== false ) {
                                        $obj->setMetadataValues( array( 'Sha1base36' => $hash ) );
                                        $obj->sync_metadata(); // save to Swift
                                        wfProfileOut( __METHOD__ );
                                        return true; // success
                                }
                        }
                }
                trigger_error( "Unable to set SHA-1 metadata for $path", E_USER_WARNING );
                $obj->setMetadataValues( array( 'Sha1base36' => false ) );
                wfProfileOut( __METHOD__ );
                return false; // failed
        }

        /**
         * @see FileBackendStore::doGetFileContentsMulti()
         * @return Array
         */
        protected function doGetFileContentsMulti( array $params ) {
                $contents = array();

                $ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
                // Blindly create tmp files and stream to them, catching any exception if the file does
                // not exist. Doing stats here is useless and will loop infinitely in addMissingMetadata().
                foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
                        $cfOps = array(); // (path => CF_Async_Op)

                        foreach ( $pathBatch as $path ) { // each path in this concurrent batch
                                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                                if ( $srcRel === null ) {
                                        $contents[$path] = false;
                                        continue;
                                }
                                $data = false;
                                try {
                                        $sContObj = $this->getContainer( $srcCont );
                                        $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                                        // Create a new temporary memory file...
                                        $handle = fopen( 'php://temp', 'wb' );
                                        if ( $handle ) {
                                                $headers = $this->headersFromParams( $params );
                                                if ( count( $pathBatch ) > 1 ) {
                                                        $cfOps[$path] = $obj->stream_async( $handle, $headers );
                                                        $cfOps[$path]->_file_handle = $handle; // close this later
                                                } else {
                                                        $obj->stream( $handle, $headers );
                                                        rewind( $handle ); // start from the beginning
                                                        $data = stream_get_contents( $handle );
                                                        fclose( $handle );
                                                }
                                        } else {
                                                $data = false;
                                        }
                                } catch ( NoSuchContainerException $e ) {
                                        $data = false;
                                } catch ( NoSuchObjectException $e ) {
                                        $data = false;
                                } catch ( CloudFilesException $e ) { // some other exception?
                                        $data = false;
                                        $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                                }
                                $contents[$path] = $data;
                        }

                        $batch = new CF_Async_Op_Batch( $cfOps );
                        $cfOps = $batch->execute();
                        foreach ( $cfOps as $path => $cfOp ) {
                                try {
                                        $cfOp->getLastResponse();
                                        rewind( $cfOp->_file_handle ); // start from the beginning
                                        $contents[$path] = stream_get_contents( $cfOp->_file_handle );
                                } catch ( NoSuchContainerException $e ) {
                                        $contents[$path] = false;
                                } catch ( NoSuchObjectException $e ) {
                                        $contents[$path] = false;
                                } catch ( CloudFilesException $e ) { // some other exception?
                                        $contents[$path] = false;
                                        $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                                }
                                fclose( $cfOp->_file_handle ); // close open handle
                        }
                }

                return $contents;
        }

        /**
         * @see FileBackendStore::doDirectoryExists()
         * @return bool|null
         */
        protected function doDirectoryExists( $fullCont, $dir, array $params ) {
                try {
                        $container = $this->getContainer( $fullCont );
                        $prefix = ( $dir == '' ) ? null : "{$dir}/";
                        return ( count( $container->list_objects( 1, null, $prefix ) ) > 0 );
                } catch ( NoSuchContainerException $e ) {
                        return false;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, null, __METHOD__,
                                array( 'cont' => $fullCont, 'dir' => $dir ) );
                }

                return null; // error
        }

        /**
         * @see FileBackendStore::getDirectoryListInternal()
         * @return SwiftFileBackendDirList
         */
        public function getDirectoryListInternal( $fullCont, $dir, array $params ) {
                return new SwiftFileBackendDirList( $this, $fullCont, $dir, $params );
        }

        /**
         * @see FileBackendStore::getFileListInternal()
         * @return SwiftFileBackendFileList
         */
        public function getFileListInternal( $fullCont, $dir, array $params ) {
                return new SwiftFileBackendFileList( $this, $fullCont, $dir, $params );
        }

        /**
         * Do not call this function outside of SwiftFileBackendFileList
         *
         * @param string $fullCont Resolved container name
         * @param string $dir Resolved storage directory with no trailing slash
         * @param string|null $after Storage path of file to list items after
         * @param $limit integer Max number of items to list
         * @param array $params Parameters for getDirectoryList()
         * @return Array List of resolved paths of directories directly under $dir
         */
        public function getDirListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
                $dirs = array();
                if ( $after === INF ) {
                        return $dirs; // nothing more
                }

                wfProfileIn( __METHOD__ . '-' . $this->name );
                try {
                        $container = $this->getContainer( $fullCont );
                        $prefix = ( $dir == '' ) ? null : "{$dir}/";
                        // Non-recursive: only list dirs right under $dir
                        if ( !empty( $params['topOnly'] ) ) {
                                $objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
                                foreach ( $objects as $object ) { // files and directories
                                        if ( substr( $object, -1 ) === '/' ) {
                                                $dirs[] = $object; // directories end in '/'
                                        }
                                }
                        // Recursive: list all dirs under $dir and its subdirs
                        } else {
                                // Get directory from last item of prior page
                                $lastDir = $this->getParentDir( $after ); // must be first page
                                $objects = $container->list_objects( $limit, $after, $prefix );
                                foreach ( $objects as $object ) { // files
                                        $objectDir = $this->getParentDir( $object ); // directory of object
                                        if ( $objectDir !== false && $objectDir !== $dir ) {
                                                // Swift stores paths in UTF-8, using binary sorting.
                                                // See function "create_container_table" in common/db.py.
                                                // If a directory is not "greater" than the last one,
                                                // then it was already listed by the calling iterator.
                                                if ( strcmp( $objectDir, $lastDir ) > 0 ) {
                                                        $pDir = $objectDir;
                                                        do { // add dir and all its parent dirs
                                                                $dirs[] = "{$pDir}/";
                                                                $pDir = $this->getParentDir( $pDir );
                                                        } while ( $pDir !== false // sanity
                                                                && strcmp( $pDir, $lastDir ) > 0 // not done already
                                                                && strlen( $pDir ) > strlen( $dir ) // within $dir
                                                        );
                                                }
                                                $lastDir = $objectDir;
                                        }
                                }
                        }
                        // Page on the unfiltered directory listing (what is returned may be filtered)
                        if ( count( $objects ) < $limit ) {
                                $after = INF; // avoid a second RTT
                        } else {
                                $after = end( $objects ); // update last item
                        }
                } catch ( NoSuchContainerException $e ) {
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, null, __METHOD__,
                                array( 'cont' => $fullCont, 'dir' => $dir ) );
                }
                wfProfileOut( __METHOD__ . '-' . $this->name );

                return $dirs;
        }

        protected function getParentDir( $path ) {
                return ( strpos( $path, '/' ) !== false ) ? dirname( $path ) : false;
        }

        /**
         * Do not call this function outside of SwiftFileBackendFileList
         *
         * @param string $fullCont Resolved container name
         * @param string $dir Resolved storage directory with no trailing slash
         * @param string|null $after Storage path of file to list items after
         * @param $limit integer Max number of items to list
         * @param array $params Parameters for getDirectoryList()
         * @return Array List of resolved paths of files under $dir
         */
        public function getFileListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
                $files = array();
                if ( $after === INF ) {
                        return $files; // nothing more
                }

                wfProfileIn( __METHOD__ . '-' . $this->name );
                try {
                        $container = $this->getContainer( $fullCont );
                        $prefix = ( $dir == '' ) ? null : "{$dir}/";
                        // Non-recursive: only list files right under $dir
                        if ( !empty( $params['topOnly'] ) ) { // files and dirs
                                if ( !empty( $params['adviseStat'] ) ) {
                                        $limit = min( $limit, self::CACHE_CHEAP_SIZE );
                                        // Note: get_objects() does not include directories
                                        $objects = $this->loadObjectListing( $params, $dir,
                                                $container->get_objects( $limit, $after, $prefix, null, '/' ) );
                                        $files = $objects;
                                } else {
                                        $objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
                                        foreach ( $objects as $object ) { // files and directories
                                                if ( substr( $object, -1 ) !== '/' ) {
                                                        $files[] = $object; // directories end in '/'
                                                }
                                        }
                                }
                        // Recursive: list all files under $dir and its subdirs
                        } else { // files
                                if ( !empty( $params['adviseStat'] ) ) {
                                        $limit = min( $limit, self::CACHE_CHEAP_SIZE );
                                        $objects = $this->loadObjectListing( $params, $dir,
                                                $container->get_objects( $limit, $after, $prefix ) );
                                } else {
                                        $objects = $container->list_objects( $limit, $after, $prefix );
                                }
                                $files = $objects;
                        }
                        // Page on the unfiltered object listing (what is returned may be filtered)
                        if ( count( $objects ) < $limit ) {
                                $after = INF; // avoid a second RTT
                        } else {
                                $after = end( $objects ); // update last item
                        }
                } catch ( NoSuchContainerException $e ) {
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, null, __METHOD__,
                                array( 'cont' => $fullCont, 'dir' => $dir ) );
                }
                wfProfileOut( __METHOD__ . '-' . $this->name );

                return $files;
        }

        /**
         * Load a list of objects that belong under $dir into stat cache
         * and return a list of the names of the objects in the same order.
         *
         * @param array $params Parameters for getDirectoryList()
         * @param string $dir Resolved container directory path
         * @param array $cfObjects List of CF_Object items
         * @return array List of object names
         */
        private function loadObjectListing( array $params, $dir, array $cfObjects ) {
                $names = array();
                $storageDir = rtrim( $params['dir'], '/' );
                $suffixStart = ( $dir === '' ) ? 0 : strlen( $dir ) + 1; // size of "path/to/dir/"
                // Iterate over the list *backwards* as this primes the stat cache, which is LRU.
                // If this fills the cache and the caller stats an uncached file before stating
                // the ones on the listing, there would be zero cache hits if this went forwards.
                for ( end( $cfObjects ); key( $cfObjects ) !== null; prev( $cfObjects ) ) {
                        $object = current( $cfObjects );
                        $path = "{$storageDir}/" . substr( $object->name, $suffixStart );
                        $val = array(
                                // Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT" to TS_MW
                                'mtime'  => wfTimestamp( TS_MW, $object->last_modified ),
                                'size'   => (int)$object->content_length,
                                'latest' => false // eventually consistent
                        );
                        $this->cheapCache->set( $path, 'stat', $val );
                        $names[] = $object->name;
                }
                return array_reverse( $names ); // keep the paths in original order
        }

        /**
         * @see FileBackendStore::doGetFileSha1base36()
         * @return bool
         */
        protected function doGetFileSha1base36( array $params ) {
                $stat = $this->getFileStat( $params );
                if ( $stat ) {
                        if ( !isset( $stat['sha1'] ) ) {
                                // Stat entries filled by file listings don't include SHA1
                                $this->clearCache( array( $params['src'] ) );
                                $stat = $this->getFileStat( $params );
                        }
                        return $stat['sha1'];
                } else {
                        return false;
                }
        }

        /**
         * @see FileBackendStore::doStreamFile()
         * @return Status
         */
        protected function doStreamFile( array $params ) {
                $status = Status::newGood();

                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                if ( $srcRel === null ) {
                        $status->fatal( 'backend-fail-invalidpath', $params['src'] );
                }

                try {
                        $cont = $this->getContainer( $srcCont );
                } catch ( NoSuchContainerException $e ) {
                        $status->fatal( 'backend-fail-stream', $params['src'] );
                        return $status;
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                        return $status;
                }

                try {
                        $output = fopen( 'php://output', 'wb' );
                        $obj = new CF_Object( $cont, $srcRel, false, false ); // skip HEAD
                        $obj->stream( $output, $this->headersFromParams( $params ) );
                } catch ( NoSuchObjectException $e ) {
                        $status->fatal( 'backend-fail-stream', $params['src'] );
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, $status, __METHOD__, $params );
                }

                return $status;
        }

        /**
         * @see FileBackendStore::doGetLocalCopyMulti()
         * @return null|TempFSFile
         */
        protected function doGetLocalCopyMulti( array $params ) {
                $tmpFiles = array();

                $ep = array_diff_key( $params, array( 'srcs' => 1 ) ); // for error logging
                // Blindly create tmp files and stream to them, catching any exception if the file does
                // not exist. Doing a stat here is useless causes infinite loops in addMissingMetadata().
                foreach ( array_chunk( $params['srcs'], $params['concurrency'] ) as $pathBatch ) {
                        $cfOps = array(); // (path => CF_Async_Op)

                        foreach ( $pathBatch as $path ) { // each path in this concurrent batch
                                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                                if ( $srcRel === null ) {
                                        $tmpFiles[$path] = null;
                                        continue;
                                }
                                $tmpFile = null;
                                try {
                                        $sContObj = $this->getContainer( $srcCont );
                                        $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                                        // Get source file extension
                                        $ext = FileBackend::extensionFromPath( $path );
                                        // Create a new temporary file...
                                        $tmpFile = TempFSFile::factory( 'localcopy_', $ext );
                                        if ( $tmpFile ) {
                                                $handle = fopen( $tmpFile->getPath(), 'wb' );
                                                if ( $handle ) {
                                                        $headers = $this->headersFromParams( $params );
                                                        if ( count( $pathBatch ) > 1 ) {
                                                                $cfOps[$path] = $obj->stream_async( $handle, $headers );
                                                                $cfOps[$path]->_file_handle = $handle; // close this later
                                                        } else {
                                                                $obj->stream( $handle, $headers );
                                                                fclose( $handle );
                                                        }
                                                } else {
                                                        $tmpFile = null;
                                                }
                                        }
                                } catch ( NoSuchContainerException $e ) {
                                        $tmpFile = null;
                                } catch ( NoSuchObjectException $e ) {
                                        $tmpFile = null;
                                } catch ( CloudFilesException $e ) { // some other exception?
                                        $tmpFile = null;
                                        $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                                }
                                $tmpFiles[$path] = $tmpFile;
                        }

                        $batch = new CF_Async_Op_Batch( $cfOps );
                        $cfOps = $batch->execute();
                        foreach ( $cfOps as $path => $cfOp ) {
                                try {
                                        $cfOp->getLastResponse();
                                } catch ( NoSuchContainerException $e ) {
                                        $tmpFiles[$path] = null;
                                } catch ( NoSuchObjectException $e ) {
                                        $tmpFiles[$path] = null;
                                } catch ( CloudFilesException $e ) { // some other exception?
                                        $tmpFiles[$path] = null;
                                        $this->handleException( $e, null, __METHOD__, array( 'src' => $path ) + $ep );
                                }
                                fclose( $cfOp->_file_handle ); // close open handle
                        }
                }

                return $tmpFiles;
        }

        /**
         * @see FileBackendStore::getFileHttpUrl()
         * @return string|null
         */
        public function getFileHttpUrl( array $params ) {
                if ( $this->swiftTempUrlKey != '' ||
                        ( $this->rgwS3AccessKey != '' && $this->rgwS3SecretKey != '' ) )
                {
                        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
                        if ( $srcRel === null ) {
                                return null; // invalid path
                        }
                        try {
                                $ttl = isset( $params['ttl'] ) ? $params['ttl'] : 86400;
                                $sContObj = $this->getContainer( $srcCont );
                                $obj = new CF_Object( $sContObj, $srcRel, false, false ); // skip HEAD
                                if ( $this->swiftTempUrlKey != '' ) {
                                        return $obj->get_temp_url( $this->swiftTempUrlKey, $ttl, "GET" );
                                } else { // give S3 API URL for rgw
                                        $expires = time() + $ttl;
                                        // Path for signature starts with the bucket
                                        $spath = '/' . rawurlencode( $srcCont ) . '/' .
                                                str_replace( '%2F', '/', rawurlencode( $srcRel ) );
                                        // Calculate the hash
                                        $signature = base64_encode( hash_hmac(
                                                'sha1',
                                                "GET\n\n\n{$expires}\n{$spath}",
                                                $this->rgwS3SecretKey,
                                                true // raw
                                        ) );
                                        // See http://s3.amazonaws.com/doc/s3-developer-guide/RESTAuthentication.html.
                                        // Note: adding a newline for empty CanonicalizedAmzHeaders does not work.
                                        return wfAppendQuery(
                                                str_replace( '/swift/v1', '', // S3 API is the rgw default
                                                        $sContObj->cfs_http->getStorageUrl() . $spath ),
                                                array(
                                                        'Signature' => $signature,
                                                        'Expires' => $expires,
                                                        'AWSAccessKeyId' => $this->rgwS3AccessKey )
                                        );
                                }
                        } catch ( NoSuchContainerException $e ) {
                        } catch ( CloudFilesException $e ) { // some other exception?
                                $this->handleException( $e, null, __METHOD__, $params );
                        }
                }
                return null;
        }

        /**
         * @see FileBackendStore::directoriesAreVirtual()
         * @return bool
         */
        protected function directoriesAreVirtual() {
                return true;
        }

        /**
         * Get headers to send to Swift when reading a file based
         * on a FileBackend params array, e.g. that of getLocalCopy().
         * $params is currently only checked for a 'latest' flag.
         *
         * @param array $params
         * @return Array
         */
        protected function headersFromParams( array $params ) {
                $hdrs = array();
                if ( !empty( $params['latest'] ) ) {
                        $hdrs[] = 'X-Newest: true';
                }
                return $hdrs;
        }

        /**
         * @see FileBackendStore::doExecuteOpHandlesInternal()
         * @return Array List of corresponding Status objects
         */
        protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
                $statuses = array();

                $cfOps = array(); // list of CF_Async_Op objects
                foreach ( $fileOpHandles as $index => $fileOpHandle ) {
                        $cfOps[$index] = $fileOpHandle->cfOp;
                }
                $batch = new CF_Async_Op_Batch( $cfOps );

                $cfOps = $batch->execute();
                foreach ( $cfOps as $index => $cfOp ) {
                        $status = Status::newGood();
                        $function = '_getResponse' . $fileOpHandles[$index]->call;
                        try { // catch exceptions; update status
                                $this->$function( $cfOp, $status, $fileOpHandles[$index]->params );
                                $this->purgeCDNCache( $fileOpHandles[$index]->affectedObjects );
                        } catch ( CloudFilesException $e ) { // some other exception?
                                $this->handleException( $e, $status,
                                        __CLASS__ . ":$function", $fileOpHandles[$index]->params );
                        }
                        $statuses[$index] = $status;
                }

                return $statuses;
        }

        /**
         * Set read/write permissions for a Swift container.
         *
         * $readGrps is a list of the possible criteria for a request to have
         * access to read a container. Each item is one of the following formats:
         *   - account:user        : Grants access if the request is by the given user
         *   - ".r:<regex>"        : Grants access if the request is from a referrer host that
         *                           matches the expression and the request is not for a listing.
         *                           Setting this to '*' effectively makes a container public.
         *   -".rlistings:<regex>" : Grants access if the request is from a referrer host that
         *                           matches the expression and the request is for a listing.
         *
         * $writeGrps is a list of the possible criteria for a request to have
         * access to write to a container. Each item is of the following format:
         *   - account:user       : Grants access if the request is by the given user
         *
         * @see http://swift.openstack.org/misc.html#acls
         *
         * In general, we don't allow listings to end-users. It's not useful, isn't well-defined
         * (lists are truncated to 10000 item with no way to page), and is just a performance risk.
         *
         * @param $contObj CF_Container Swift container
         * @param array $readGrps List of read access routes
         * @param array $writeGrps List of write access routes
         * @return Status
         */
        protected function setContainerAccess(
                CF_Container $contObj, array $readGrps, array $writeGrps
        ) {
                $creds = $contObj->cfs_auth->export_credentials();

                $url = $creds['storage_url'] . '/' . rawurlencode( $contObj->name );

                // Note: 10 second timeout consistent with php-cloudfiles
                $req = MWHttpRequest::factory( $url, array( 'method' => 'POST', 'timeout' => 10 ) );
                $req->setHeader( 'X-Auth-Token', $creds['auth_token'] );
                $req->setHeader( 'X-Container-Read', implode( ',', $readGrps ) );
                $req->setHeader( 'X-Container-Write', implode( ',', $writeGrps ) );

                return $req->execute(); // should return 204
        }

        /**
         * Purge the CDN cache of affected objects if CDN caching is enabled.
         * This is for Rackspace/Akamai CDNs.
         *
         * @param array $objects List of CF_Object items
         * @return void
         */
        public function purgeCDNCache( array $objects ) {
                if ( $this->swiftUseCDN && $this->swiftCDNPurgable ) {
                        foreach ( $objects as $object ) {
                                try {
                                        $object->purge_from_cdn();
                                } catch ( CDNNotEnabledException $e ) {
                                        // CDN not enabled; nothing to see here
                                } catch ( CloudFilesException $e ) {
                                        $this->handleException( $e, null, __METHOD__,
                                                array( 'cont' => $object->container->name, 'obj' => $object->name ) );
                                }
                        }
                }
        }

        /**
         * Get an authenticated connection handle to the Swift proxy
         *
         * @throws CloudFilesException
         * @throws CloudFilesException|Exception
         * @return CF_Connection|bool False on failure
         */
        protected function getConnection() {
                if ( $this->connException instanceof CloudFilesException ) {
                        if ( ( time() - $this->connErrorTime ) < 60 ) {
                                throw $this->connException; // failed last attempt; don't bother
                        } else { // actually retry this time
                                $this->connException = null;
                                $this->connErrorTime = 0;
                        }
                }
                // Session keys expire after a while, so we renew them periodically
                $reAuth = ( ( time() - $this->sessionStarted ) > $this->authTTL );
                // Authenticate with proxy and get a session key...
                if ( !$this->conn || $reAuth ) {
                        $this->sessionStarted = 0;
                        $this->connContainerCache->clear();
                        $cacheKey = $this->getCredsCacheKey( $this->auth->username );
                        $creds = $this->srvCache->get( $cacheKey ); // credentials
                        if ( is_array( $creds ) ) { // cache hit
                                $this->auth->load_cached_credentials(
                                        $creds['auth_token'], $creds['storage_url'], $creds['cdnm_url'] );
                                $this->sessionStarted = time() - ceil( $this->authTTL / 2 ); // skew for worst case
                        } else { // cache miss
                                try {
                                        $this->auth->authenticate();
                                        $creds = $this->auth->export_credentials();
                                        $this->srvCache->add( $cacheKey, $creds, ceil( $this->authTTL / 2 ) ); // cache
                                        $this->sessionStarted = time();
                                } catch ( CloudFilesException $e ) {
                                        $this->connException = $e; // don't keep re-trying
                                        $this->connErrorTime = time();
                                        throw $e; // throw it back
                                }
                        }
                        if ( $this->conn ) { // re-authorizing?
                                $this->conn->close(); // close active cURL handles in CF_Http object
                        }
                        $this->conn = new CF_Connection( $this->auth );
                }
                return $this->conn;
        }

        /**
         * Close the connection to the Swift proxy
         *
         * @return void
         */
        protected function closeConnection() {
                if ( $this->conn ) {
                        $this->conn->close(); // close active cURL handles in CF_Http object
                        $this->conn = null;
                        $this->sessionStarted = 0;
                        $this->connContainerCache->clear();
                }
        }

        /**
         * Get the cache key for a container
         *
         * @param $username string
         * @return string
         */
        private function getCredsCacheKey( $username ) {
                return wfMemcKey( 'backend', $this->getName(), 'usercreds', $username );
        }

        /**
         * Get a Swift container object, possibly from process cache.
         * Use $reCache if the file count or byte count is needed.
         *
         * @param string $container Container name
         * @param bool $bypassCache Bypass all caches and load from Swift
         * @return CF_Container
         * @throws CloudFilesException
         */
        protected function getContainer( $container, $bypassCache = false ) {
                $conn = $this->getConnection(); // Swift proxy connection
                if ( $bypassCache ) { // purge cache
                        $this->connContainerCache->clear( $container );
                } elseif ( !$this->connContainerCache->has( $container, 'obj' ) ) {
                        $this->primeContainerCache( array( $container ) ); // check persistent cache
                }
                if ( !$this->connContainerCache->has( $container, 'obj' ) ) {
                        $contObj = $conn->get_container( $container );
                        // NoSuchContainerException not thrown: container must exist
                        $this->connContainerCache->set( $container, 'obj', $contObj ); // cache it
                        if ( !$bypassCache ) {
                                $this->setContainerCache( $container, // update persistent cache
                                        array( 'bytes' => $contObj->bytes_used, 'count' => $contObj->object_count )
                                );
                        }
                }
                return $this->connContainerCache->get( $container, 'obj' );
        }

        /**
         * Create a Swift container
         *
         * @param string $container Container name
         * @return CF_Container
         * @throws CloudFilesException
         */
        protected function createContainer( $container ) {
                $conn = $this->getConnection(); // Swift proxy connection
                $contObj = $conn->create_container( $container );
                $this->connContainerCache->set( $container, 'obj', $contObj ); // cache
                return $contObj;
        }

        /**
         * Delete a Swift container
         *
         * @param string $container Container name
         * @return void
         * @throws CloudFilesException
         */
        protected function deleteContainer( $container ) {
                $conn = $this->getConnection(); // Swift proxy connection
                $this->connContainerCache->clear( $container ); // purge
                $conn->delete_container( $container );
        }

        /**
         * @see FileBackendStore::doPrimeContainerCache()
         * @return void
         */
        protected function doPrimeContainerCache( array $containerInfo ) {
                try {
                        $conn = $this->getConnection(); // Swift proxy connection
                        foreach ( $containerInfo as $container => $info ) {
                                $contObj = new CF_Container( $conn->cfs_auth, $conn->cfs_http,
                                        $container, $info['count'], $info['bytes'] );
                                $this->connContainerCache->set( $container, 'obj', $contObj );
                        }
                } catch ( CloudFilesException $e ) { // some other exception?
                        $this->handleException( $e, null, __METHOD__, array() );
                }
        }

        /**
         * Log an unexpected exception for this backend.
         * This also sets the Status object to have a fatal error.
         *
         * @param $e Exception
         * @param $status Status|null
         * @param $func string
         * @param array $params
         * @return void
         */
        protected function handleException( Exception $e, $status, $func, array $params ) {
                if ( $status instanceof Status ) {
                        if ( $e instanceof AuthenticationException ) {
                                $status->fatal( 'backend-fail-connect', $this->name );
                        } else {
                                $status->fatal( 'backend-fail-internal', $this->name );
                        }
                }
                if ( $e->getMessage() ) {
                        trigger_error( "$func: " . $e->getMessage(), E_USER_WARNING );
                }
                if ( $e instanceof InvalidResponseException ) { // possibly a stale token
                        $this->srvCache->delete( $this->getCredsCacheKey( $this->auth->username ) );
                        $this->closeConnection(); // force a re-connect and re-auth next time
                }
                wfDebugLog( 'SwiftBackend',
                        get_class( $e ) . " in '{$func}' (given '" . FormatJson::encode( $params ) . "')" .
                        ( $e->getMessage() ? ": {$e->getMessage()}" : "" )
                );
        }
}

/**
 * @see FileBackendStoreOpHandle
 */
class SwiftFileOpHandle extends FileBackendStoreOpHandle {
        /** @var CF_Async_Op */
        public $cfOp;
        /** @var Array */
        public $affectedObjects = array();

        public function __construct( $backend, array $params, $call, CF_Async_Op $cfOp ) {
                $this->backend = $backend;
                $this->params = $params;
                $this->call = $call;
                $this->cfOp = $cfOp;
        }
}

/**
 * SwiftFileBackend helper class to page through listings.
 * Swift also has a listing limit of 10,000 objects for sanity.
 * Do not use this class from places outside SwiftFileBackend.
 *
 * @ingroup FileBackend
 */
abstract class SwiftFileBackendList implements Iterator {
        /** @var Array */
        protected $bufferIter = array();
        protected $bufferAfter = null; // string; list items *after* this path
        protected $pos = 0; // integer
        /** @var Array */
        protected $params = array();

        /** @var SwiftFileBackend */
        protected $backend;
        protected $container; // string; container name
        protected $dir; // string; storage directory
        protected $suffixStart; // integer

        const PAGE_SIZE = 9000; // file listing buffer size

        /**
         * @param $backend SwiftFileBackend
         * @param string $fullCont Resolved container name
         * @param string $dir Resolved directory relative to container
         * @param array $params
         */
        public function __construct( SwiftFileBackend $backend, $fullCont, $dir, array $params ) {
                $this->backend = $backend;
                $this->container = $fullCont;
                $this->dir = $dir;
                if ( substr( $this->dir, -1 ) === '/' ) {
                        $this->dir = substr( $this->dir, 0, -1 ); // remove trailing slash
                }
                if ( $this->dir == '' ) { // whole container
                        $this->suffixStart = 0;
                } else { // dir within container
                        $this->suffixStart = strlen( $this->dir ) + 1; // size of "path/to/dir/"
                }
                $this->params = $params;
        }

        /**
         * @see Iterator::key()
         * @return integer
         */
        public function key() {
                return $this->pos;
        }

        /**
         * @see Iterator::next()
         * @return void
         */
        public function next() {
                // Advance to the next file in the page
                next( $this->bufferIter );
                ++$this->pos;
                // Check if there are no files left in this page and
                // advance to the next page if this page was not empty.
                if ( !$this->valid() && count( $this->bufferIter ) ) {
                        $this->bufferIter = $this->pageFromList(
                                $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
                        ); // updates $this->bufferAfter
                }
        }

        /**
         * @see Iterator::rewind()
         * @return void
         */
        public function rewind() {
                $this->pos = 0;
                $this->bufferAfter = null;
                $this->bufferIter = $this->pageFromList(
                        $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE, $this->params
                ); // updates $this->bufferAfter
        }

        /**
         * @see Iterator::valid()
         * @return bool
         */
        public function valid() {
                if ( $this->bufferIter === null ) {
                        return false; // some failure?
                } else {
                        return ( current( $this->bufferIter ) !== false ); // no paths can have this value
                }
        }

        /**
         * Get the given list portion (page)
         *
         * @param string $container Resolved container name
         * @param string $dir Resolved path relative to container
         * @param $after string|null
         * @param $limit integer
         * @param array $params
         * @return Traversable|Array|null Returns null on failure
         */
        abstract protected function pageFromList( $container, $dir, &$after, $limit, array $params );
}

/**
 * Iterator for listing directories
 */
class SwiftFileBackendDirList extends SwiftFileBackendList {
        /**
         * @see Iterator::current()
         * @return string|bool String (relative path) or false
         */
        public function current() {
                return substr( current( $this->bufferIter ), $this->suffixStart, -1 );
        }

        /**
         * @see SwiftFileBackendList::pageFromList()
         * @return Array|null
         */
        protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
                return $this->backend->getDirListPageInternal( $container, $dir, $after, $limit, $params );
        }
}

/**
 * Iterator for listing regular files
 */
class SwiftFileBackendFileList extends SwiftFileBackendList {
        /**
         * @see Iterator::current()
         * @return string|bool String (relative path) or false
         */
        public function current() {
                return substr( current( $this->bufferIter ), $this->suffixStart );
        }

        /**
         * @see SwiftFileBackendList::pageFromList()
         * @return Array|null
         */
        protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
                return $this->backend->getFileListPageInternal( $container, $dir, $after, $limit, $params );
        }
}