User::isSafeToLoad() should return false if MW_NO_SESSION

[mediawiki.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 (or Ceph RGW) based file backend.
 *
 * 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 MultiHttpClient */
        protected $http;

        /** @var int TTL in seconds */
        protected $authTTL;

        /** @var string Authentication base URL (without version) */
        protected $swiftAuthUrl;

        /** @var string Swift user (account:user) to authenticate as */
        protected $swiftUser;

        /** @var string Secret key for user */
        protected $swiftKey;

        /** @var string Shared secret value for making temp URLs */
        protected $swiftTempUrlKey;

        /** @var string S3 access key (RADOS Gateway) */
        protected $rgwS3AccessKey;

        /** @var string S3 authentication key (RADOS Gateway) */
        protected $rgwS3SecretKey;

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

        /** @var ProcessCacheLRU Container stat cache */
        protected $containerStatCache;

        /** @var array */
        protected $authCreds;

        /** @var int UNIX timestamp */
        protected $authSessionTimestamp = 0;

        /** @var int UNIX timestamp */
        protected $authErrorTimestamp = null;

        /** @var bool Whether the server is an Ceph RGW */
        protected $isRGW = false;

        /**
         * @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.
         *   - 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     : Rados 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     : Rados 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 );
                // Required settings
                $this->swiftAuthUrl = $config['swiftAuthUrl'];
                $this->swiftUser = $config['swiftUser'];
                $this->swiftKey = $config['swiftKey'];
                // Optional settings
                $this->authTTL = isset( $config['swiftAuthTTL'] )
                        ? $config['swiftAuthTTL']
                        : 15 * 60; // some sane number
                $this->swiftTempUrlKey = isset( $config['swiftTempUrlKey'] )
                        ? $config['swiftTempUrlKey']
                        : '';
                $this->shardViaHashLevels = isset( $config['shardViaHashLevels'] )
                        ? $config['shardViaHashLevels']
                        : '';
                $this->rgwS3AccessKey = isset( $config['rgwS3AccessKey'] )
                        ? $config['rgwS3AccessKey']
                        : '';
                $this->rgwS3SecretKey = isset( $config['rgwS3SecretKey'] )
                        ? $config['rgwS3SecretKey']
                        : '';
                // HTTP helper client
                $this->http = new MultiHttpClient( [] );
                // Cache container information to mask latency
                if ( isset( $config['wanCache'] ) && $config['wanCache'] instanceof WANObjectCache ) {
                        $this->memCache = $config['wanCache'];
                }
                // Process cache for container info
                $this->containerStatCache = new ProcessCacheLRU( 300 );
                // Cache auth token information to avoid RTTs
                if ( !empty( $config['cacheAuthInfo'] ) ) {
                        if ( PHP_SAPI === 'cli' ) {
                                // Preferrably memcached
                                $this->srvCache = ObjectCache::getLocalClusterInstance();
                        } else {
                                // Look for APC, XCache, WinCache, ect...
                                $this->srvCache = ObjectCache::getLocalServerInstance( CACHE_NONE );
                        }
                } else {
                        $this->srvCache = new EmptyBagOStuff();
                }
        }

        public function getFeatures() {
                return ( FileBackend::ATTR_UNICODE_PATHS |
                        FileBackend::ATTR_HEADERS | FileBackend::ATTR_METADATA );
        }

        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;
        }

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

                return is_array( $this->getContainerStat( $container ) );
        }

        /**
         * Sanitize and filter the custom headers from a $params array.
         * Only allows certain "standard" Content- and X-Content- headers.
         *
         * @param array $params
         * @return array Sanitized value of 'headers' field in $params
         */
        protected function sanitizeHdrs( array $params ) {
                return isset( $params['headers'] )
                        ? $this->getCustomHeaders( $params['headers'] )
                        : [];

        }

        /**
         * @param array $rawHeaders
         * @return array Custom non-metadata HTTP headers
         */
        protected function getCustomHeaders( array $rawHeaders ) {
                $headers = [];

                // Normalize casing, and strip out illegal headers
                foreach ( $rawHeaders as $name => $value ) {
                        $name = strtolower( $name );
                        if ( preg_match( '/^content-(type|length)$/', $name ) ) {
                                continue; // blacklisted
                        } elseif ( preg_match( '/^(x-)?content-/', $name ) ) {
                                $headers[$name] = $value; // allowed
                        } elseif ( preg_match( '/^content-(disposition)/', $name ) ) {
                                $headers[$name] = $value; // allowed
                        }
                }
                // By default, Swift has annoyingly low maximum header value limits
                if ( isset( $headers['content-disposition'] ) ) {
                        $disposition = '';
                        // @note: assume FileBackend::makeContentDisposition() already used
                        foreach ( explode( ';', $headers['content-disposition'] ) as $part ) {
                                $part = trim( $part );
                                $new = ( $disposition === '' ) ? $part : "{$disposition};{$part}";
                                if ( strlen( $new ) <= 255 ) {
                                        $disposition = $new;
                                } else {
                                        break; // too long; sigh
                                }
                        }
                        $headers['content-disposition'] = $disposition;
                }

                return $headers;
        }

        /**
         * @param array $rawHeaders
         * @return array Custom metadata headers
         */
        protected function getMetadataHeaders( array $rawHeaders ) {
                $headers = [];
                foreach ( $rawHeaders as $name => $value ) {
                        $name = strtolower( $name );
                        if ( strpos( $name, 'x-object-meta-' ) === 0 ) {
                                $headers[$name] = $value;
                        }
                }

                return $headers;
        }

        /**
         * @param array $rawHeaders
         * @return array Custom metadata headers with prefix removed
         */
        protected function getMetadata( array $rawHeaders ) {
                $metadata = [];
                foreach ( $this->getMetadataHeaders( $rawHeaders ) as $name => $value ) {
                        $metadata[substr( $name, strlen( 'x-object-meta-' ) )] = $value;
                }

                return $metadata;
        }

        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;
                }

                $sha1Hash = Wikimedia\base_convert( sha1( $params['content'] ), 16, 36, 31 );
                $contentType = isset( $params['headers']['content-type'] )
                        ? $params['headers']['content-type']
                        : $this->getContentType( $params['dst'], $params['content'], null );

                $reqs = [ [
                        'method' => 'PUT',
                        'url' => [ $dstCont, $dstRel ],
                        'headers' => [
                                'content-length' => strlen( $params['content'] ),
                                'etag' => md5( $params['content'] ),
                                'content-type' => $contentType,
                                'x-object-meta-sha1base36' => $sha1Hash
                        ] + $this->sanitizeHdrs( $params ),
                        'body' => $params['content']
                ] ];

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $rcode === 201 ) {
                                // good
                        } elseif ( $rcode === 412 ) {
                                $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually write the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                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;
                }

                MediaWiki\suppressWarnings();
                $sha1Hash = sha1_file( $params['src'] );
                MediaWiki\restoreWarnings();
                if ( $sha1Hash === false ) { // source doesn't exist?
                        $status->fatal( 'backend-fail-store', $params['src'], $params['dst'] );

                        return $status;
                }
                $sha1Hash = Wikimedia\base_convert( $sha1Hash, 16, 36, 31 );
                $contentType = isset( $params['headers']['content-type'] )
                        ? $params['headers']['content-type']
                        : $this->getContentType( $params['dst'], null, $params['src'] );

                $handle = fopen( $params['src'], 'rb' );
                if ( $handle === false ) { // source doesn't exist?
                        $status->fatal( 'backend-fail-store', $params['src'], $params['dst'] );

                        return $status;
                }

                $reqs = [ [
                        'method' => 'PUT',
                        'url' => [ $dstCont, $dstRel ],
                        'headers' => [
                                'content-length' => filesize( $params['src'] ),
                                'etag' => md5_file( $params['src'] ),
                                'content-type' => $contentType,
                                'x-object-meta-sha1base36' => $sha1Hash
                        ] + $this->sanitizeHdrs( $params ),
                        'body' => $handle // resource
                ] ];

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $rcode === 201 ) {
                                // good
                        } elseif ( $rcode === 412 ) {
                                $status->fatal( 'backend-fail-contenttype', $params['dst'] );
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually write the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                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;
                }

                $reqs = [ [
                        'method' => 'PUT',
                        'url' => [ $dstCont, $dstRel ],
                        'headers' => [
                                'x-copy-from' => '/' . rawurlencode( $srcCont ) .
                                        '/' . str_replace( "%2F", "/", rawurlencode( $srcRel ) )
                        ] + $this->sanitizeHdrs( $params ), // extra headers merged into object
                ] ];

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $rcode === 201 ) {
                                // good
                        } elseif ( $rcode === 404 ) {
                                $status->fatal( 'backend-fail-copy', $params['src'], $params['dst'] );
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually write the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                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;
                }

                $reqs = [
                        [
                                'method' => 'PUT',
                                'url' => [ $dstCont, $dstRel ],
                                'headers' => [
                                        'x-copy-from' => '/' . rawurlencode( $srcCont ) .
                                                '/' . str_replace( "%2F", "/", rawurlencode( $srcRel ) )
                                ] + $this->sanitizeHdrs( $params ) // extra headers merged into object
                        ]
                ];
                if ( "{$srcCont}/{$srcRel}" !== "{$dstCont}/{$dstRel}" ) {
                        $reqs[] = [
                                'method' => 'DELETE',
                                'url' => [ $srcCont, $srcRel ],
                                'headers' => []
                        ];
                }

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $request['method'] === 'PUT' && $rcode === 201 ) {
                                // good
                        } elseif ( $request['method'] === 'DELETE' && $rcode === 204 ) {
                                // good
                        } elseif ( $rcode === 404 ) {
                                $status->fatal( 'backend-fail-move', $params['src'], $params['dst'] );
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually move the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                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;
                }

                $reqs = [ [
                        'method' => 'DELETE',
                        'url' => [ $srcCont, $srcRel ],
                        'headers' => []
                ] ];

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $rcode === 204 ) {
                                // good
                        } elseif ( $rcode === 404 ) {
                                if ( empty( $params['ignoreMissingSource'] ) ) {
                                        $status->fatal( 'backend-fail-delete', $params['src'] );
                                }
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually delete the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                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;
                }

                // Fetch the old object headers/metadata...this should be in stat cache by now
                $stat = $this->getFileStat( [ 'src' => $params['src'], 'latest' => 1 ] );
                if ( $stat && !isset( $stat['xattr'] ) ) { // older cache entry
                        $stat = $this->doGetFileStat( [ 'src' => $params['src'], 'latest' => 1 ] );
                }
                if ( !$stat ) {
                        $status->fatal( 'backend-fail-describe', $params['src'] );

                        return $status;
                }

                // POST clears prior headers, so we need to merge the changes in to the old ones
                $metaHdrs = [];
                foreach ( $stat['xattr']['metadata'] as $name => $value ) {
                        $metaHdrs["x-object-meta-$name"] = $value;
                }
                $customHdrs = $this->sanitizeHdrs( $params ) + $stat['xattr']['headers'];

                $reqs = [ [
                        'method' => 'POST',
                        'url' => [ $srcCont, $srcRel ],
                        'headers' => $metaHdrs + $customHdrs
                ] ];

                $method = __METHOD__;
                $handler = function ( array $request, Status $status ) use ( $method, $params ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $request['response'];
                        if ( $rcode === 202 ) {
                                // good
                        } elseif ( $rcode === 404 ) {
                                $status->fatal( 'backend-fail-describe', $params['src'] );
                        } else {
                                $this->onError( $status, $method, $params, $rerr, $rcode, $rdesc );
                        }
                };

                $opHandle = new SwiftFileOpHandle( $this, $handler, $reqs );
                if ( !empty( $params['async'] ) ) { // deferred
                        $status->value = $opHandle;
                } else { // actually change the object in Swift
                        $status->merge( current( $this->doExecuteOpHandlesInternal( [ $opHandle ] ) ) );
                }

                return $status;
        }

        protected function doPrepareInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();

                // (a) Check if container already exists
                $stat = $this->getContainerStat( $fullCont );
                if ( is_array( $stat ) ) {
                        return $status; // already there
                } elseif ( $stat === null ) {
                        $status->fatal( 'backend-fail-internal', $this->name );
                        wfDebugLog( 'SwiftBackend', __METHOD__ . ': cannot get container stat' );

                        return $status;
                }

                // (b) Create container as needed with proper ACLs
                if ( $stat === false ) {
                        $params['op'] = 'prepare';
                        $status->merge( $this->createContainer( $fullCont, $params ) );
                }

                return $status;
        }

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

                $stat = $this->getContainerStat( $fullCont );
                if ( is_array( $stat ) ) {
                        // Make container private to end-users...
                        $status->merge( $this->setContainerAccess(
                                $fullCont,
                                [ $this->swiftUser ], // read
                                [ $this->swiftUser ] // write
                        ) );
                } elseif ( $stat === false ) {
                        $status->fatal( 'backend-fail-usable', $params['dir'] );
                } else {
                        $status->fatal( 'backend-fail-internal', $this->name );
                        wfDebugLog( 'SwiftBackend', __METHOD__ . ': cannot get container stat' );
                }

                return $status;
        }

        protected function doPublishInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();

                $stat = $this->getContainerStat( $fullCont );
                if ( is_array( $stat ) ) {
                        // Make container public to end-users...
                        $status->merge( $this->setContainerAccess(
                                $fullCont,
                                [ $this->swiftUser, '.r:*' ], // read
                                [ $this->swiftUser ] // write
                        ) );
                } elseif ( $stat === false ) {
                        $status->fatal( 'backend-fail-usable', $params['dir'] );
                } else {
                        $status->fatal( 'backend-fail-internal', $this->name );
                        wfDebugLog( 'SwiftBackend', __METHOD__ . ': cannot get container stat' );
                }

                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
                $stat = $this->getContainerStat( $fullCont, true );
                if ( $stat === false ) {
                        return $status; // ok, nothing to do
                } elseif ( !is_array( $stat ) ) {
                        $status->fatal( 'backend-fail-internal', $this->name );
                        wfDebugLog( 'SwiftBackend', __METHOD__ . ': cannot get container stat' );

                        return $status;
                }

                // (b) Delete the container if empty
                if ( $stat['count'] == 0 ) {
                        $params['op'] = 'clean';
                        $status->merge( $this->deleteContainer( $fullCont, $params ) );
                }

                return $status;
        }

        protected function doGetFileStat( array $params ) {
                $params = [ 'srcs' => [ $params['src'] ], 'concurrency' => 1 ] + $params;
                unset( $params['src'] );
                $stats = $this->doGetFileStatMulti( $params );

                return reset( $stats );
        }

        /**
         * Convert dates like "Tue, 03 Jan 2012 22:01:04 GMT"/"2013-05-11T07:37:27.678360Z".
         * Dates might also come in like "2013-05-11T07:37:27.678360" from Swift listings,
         * missing the timezone suffix (though Ceph RGW does not appear to have this bug).
         *
         * @param string $ts
         * @param int $format Output format (TS_* constant)
         * @return string
         * @throws FileBackendError
         */
        protected function convertSwiftDate( $ts, $format = TS_MW ) {
                try {
                        $timestamp = new MWTimestamp( $ts );

                        return $timestamp->getTimestamp( $format );
                } catch ( Exception $e ) {
                        throw new FileBackendError( $e->getMessage() );
                }
        }

        /**
         * Fill in any missing object metadata and save it to Swift
         *
         * @param array $objHdrs Object response headers
         * @param string $path Storage path to object
         * @return array New headers
         */
        protected function addMissingMetadata( array $objHdrs, $path ) {
                if ( isset( $objHdrs['x-object-meta-sha1base36'] ) ) {
                        return $objHdrs; // nothing to do
                }

                /** @noinspection PhpUnusedLocalVariableInspection */
                $ps = Profiler::instance()->scopedProfileIn( __METHOD__ . "-{$this->name}" );
                wfDebugLog( 'SwiftBackend', __METHOD__ . ": $path was not stored with SHA-1 metadata." );

                $objHdrs['x-object-meta-sha1base36'] = false;

                $auth = $this->getAuthentication();
                if ( !$auth ) {
                        return $objHdrs; // failed
                }

                // Find prior custom HTTP headers
                $postHeaders = $this->getCustomHeaders( $objHdrs );
                // Find prior metadata headers
                $postHeaders += $this->getMetadataHeaders( $objHdrs );

                $status = Status::newGood();
                /** @noinspection PhpUnusedLocalVariableInspection */
                $scopeLockS = $this->getScopedFileLocks( [ $path ], LockManager::LOCK_UW, $status );
                if ( $status->isOK() ) {
                        $tmpFile = $this->getLocalCopy( [ 'src' => $path, 'latest' => 1 ] );
                        if ( $tmpFile ) {
                                $hash = $tmpFile->getSha1Base36();
                                if ( $hash !== false ) {
                                        $objHdrs['x-object-meta-sha1base36'] = $hash;
                                        // Merge new SHA1 header into the old ones
                                        $postHeaders['x-object-meta-sha1base36'] = $hash;
                                        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                                        list( $rcode ) = $this->http->run( [
                                                'method' => 'POST',
                                                'url' => $this->storageUrl( $auth, $srcCont, $srcRel ),
                                                'headers' => $this->authTokenHeaders( $auth ) + $postHeaders
                                        ] );
                                        if ( $rcode >= 200 && $rcode <= 299 ) {
                                                $this->deleteFileCache( $path );

                                                return $objHdrs; // success
                                        }
                                }
                        }
                }

                wfDebugLog( 'SwiftBackend', __METHOD__ . ": unable to set SHA-1 metadata for $path" );

                return $objHdrs; // failed
        }

        protected function doGetFileContentsMulti( array $params ) {
                $contents = [];

                $auth = $this->getAuthentication();

                $ep = array_diff_key( $params, [ '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().
                $reqs = []; // (path => op)

                foreach ( $params['srcs'] as $path ) { // each path in this concurrent batch
                        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                        if ( $srcRel === null || !$auth ) {
                                $contents[$path] = false;
                                continue;
                        }
                        // Create a new temporary memory file...
                        $handle = fopen( 'php://temp', 'wb' );
                        if ( $handle ) {
                                $reqs[$path] = [
                                        'method'  => 'GET',
                                        'url'     => $this->storageUrl( $auth, $srcCont, $srcRel ),
                                        'headers' => $this->authTokenHeaders( $auth )
                                                + $this->headersFromParams( $params ),
                                        'stream'  => $handle,
                                ];
                        }
                        $contents[$path] = false;
                }

                $opts = [ 'maxConnsPerHost' => $params['concurrency'] ];
                $reqs = $this->http->runMulti( $reqs, $opts );
                foreach ( $reqs as $path => $op ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $op['response'];
                        if ( $rcode >= 200 && $rcode <= 299 ) {
                                rewind( $op['stream'] ); // start from the beginning
                                $contents[$path] = stream_get_contents( $op['stream'] );
                        } elseif ( $rcode === 404 ) {
                                $contents[$path] = false;
                        } else {
                                $this->onError( null, __METHOD__,
                                        [ 'src' => $path ] + $ep, $rerr, $rcode, $rdesc );
                        }
                        fclose( $op['stream'] ); // close open handle
                }

                return $contents;
        }

        protected function doDirectoryExists( $fullCont, $dir, array $params ) {
                $prefix = ( $dir == '' ) ? null : "{$dir}/";
                $status = $this->objectListing( $fullCont, 'names', 1, null, $prefix );
                if ( $status->isOk() ) {
                        return ( count( $status->value ) ) > 0;
                }

                return null; // error
        }

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

        /**
         * @see FileBackendStore::getFileListInternal()
         * @param string $fullCont
         * @param string $dir
         * @param array $params
         * @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 Resolved container relative path to list items after
         * @param int $limit Max number of items to list
         * @param array $params Parameters for getDirectoryList()
         * @return array List of container relative resolved paths of directories directly under $dir
         * @throws FileBackendError
         */
        public function getDirListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
                $dirs = [];
                if ( $after === INF ) {
                        return $dirs; // nothing more
                }

                $ps = Profiler::instance()->scopedProfileIn( __METHOD__ . "-{$this->name}" );

                $prefix = ( $dir == '' ) ? null : "{$dir}/";
                // Non-recursive: only list dirs right under $dir
                if ( !empty( $params['topOnly'] ) ) {
                        $status = $this->objectListing( $fullCont, 'names', $limit, $after, $prefix, '/' );
                        if ( !$status->isOk() ) {
                                throw new FileBackendError( "Iterator page I/O error: {$status->getMessage()}" );
                        }
                        $objects = $status->value;
                        foreach ( $objects as $object ) { // files and directories
                                if ( substr( $object, -1 ) === '/' ) {
                                        $dirs[] = $object; // directories end in '/'
                                }
                        }
                } else {
                        // Recursive: list all dirs under $dir and its subdirs
                        $getParentDir = function ( $path ) {
                                return ( strpos( $path, '/' ) !== false ) ? dirname( $path ) : false;
                        };

                        // Get directory from last item of prior page
                        $lastDir = $getParentDir( $after ); // must be first page
                        $status = $this->objectListing( $fullCont, 'names', $limit, $after, $prefix );

                        if ( !$status->isOk() ) {
                                throw new FileBackendError( "Iterator page I/O error: {$status->getMessage()}" );
                        }

                        $objects = $status->value;

                        foreach ( $objects as $object ) { // files
                                $objectDir = $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 = $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
                }

                return $dirs;
        }

        /**
         * 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 Resolved container relative path of file to list items after
         * @param int $limit Max number of items to list
         * @param array $params Parameters for getDirectoryList()
         * @return array List of resolved container relative paths of files under $dir
         * @throws FileBackendError
         */
        public function getFileListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
                $files = []; // list of (path, stat array or null) entries
                if ( $after === INF ) {
                        return $files; // nothing more
                }

                $ps = Profiler::instance()->scopedProfileIn( __METHOD__ . "-{$this->name}" );

                $prefix = ( $dir == '' ) ? null : "{$dir}/";
                // $objects will contain a list of unfiltered names or CF_Object items
                // Non-recursive: only list files right under $dir
                if ( !empty( $params['topOnly'] ) ) {
                        if ( !empty( $params['adviseStat'] ) ) {
                                $status = $this->objectListing( $fullCont, 'info', $limit, $after, $prefix, '/' );
                        } else {
                                $status = $this->objectListing( $fullCont, 'names', $limit, $after, $prefix, '/' );
                        }
                } else {
                        // Recursive: list all files under $dir and its subdirs
                        if ( !empty( $params['adviseStat'] ) ) {
                                $status = $this->objectListing( $fullCont, 'info', $limit, $after, $prefix );
                        } else {
                                $status = $this->objectListing( $fullCont, 'names', $limit, $after, $prefix );
                        }
                }

                // Reformat this list into a list of (name, stat array or null) entries
                if ( !$status->isOk() ) {
                        throw new FileBackendError( "Iterator page I/O error: {$status->getMessage()}" );
                }

                $objects = $status->value;
                $files = $this->buildFileObjectListing( $params, $dir, $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
                        $after = is_object( $after ) ? $after->name : $after;
                }

                return $files;
        }

        /**
         * Build a list of file objects, filtering out any directories
         * and extracting any stat info if provided in $objects (for CF_Objects)
         *
         * @param array $params Parameters for getDirectoryList()
         * @param string $dir Resolved container directory path
         * @param array $objects List of CF_Object items or object names
         * @return array List of (names,stat array or null) entries
         */
        private function buildFileObjectListing( array $params, $dir, array $objects ) {
                $names = [];
                foreach ( $objects as $object ) {
                        if ( is_object( $object ) ) {
                                if ( isset( $object->subdir ) || !isset( $object->name ) ) {
                                        continue; // virtual directory entry; ignore
                                }
                                $stat = [
                                        // Convert various random Swift dates to TS_MW
                                        'mtime'  => $this->convertSwiftDate( $object->last_modified, TS_MW ),
                                        'size'   => (int)$object->bytes,
                                        'sha1'   => null,
                                        // Note: manifiest ETags are not an MD5 of the file
                                        'md5'    => ctype_xdigit( $object->hash ) ? $object->hash : null,
                                        'latest' => false // eventually consistent
                                ];
                                $names[] = [ $object->name, $stat ];
                        } elseif ( substr( $object, -1 ) !== '/' ) {
                                // Omit directories, which end in '/' in listings
                                $names[] = [ $object, null ];
                        }
                }

                return $names;
        }

        /**
         * Do not call this function outside of SwiftFileBackendFileList
         *
         * @param string $path Storage path
         * @param array $val Stat value
         */
        public function loadListingStatInternal( $path, array $val ) {
                $this->cheapCache->set( $path, 'stat', $val );
        }

        protected function doGetFileXAttributes( array $params ) {
                $stat = $this->getFileStat( $params );
                if ( $stat ) {
                        if ( !isset( $stat['xattr'] ) ) {
                                // Stat entries filled by file listings don't include metadata/headers
                                $this->clearCache( [ $params['src'] ] );
                                $stat = $this->getFileStat( $params );
                        }

                        return $stat['xattr'];
                } else {
                        return false;
                }
        }

        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( [ $params['src'] ] );
                                $stat = $this->getFileStat( $params );
                        }

                        return $stat['sha1'];
                } else {
                        return false;
                }
        }

        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'] );
                }

                $auth = $this->getAuthentication();
                if ( !$auth || !is_array( $this->getContainerStat( $srcCont ) ) ) {
                        $status->fatal( 'backend-fail-stream', $params['src'] );

                        return $status;
                }

                $handle = fopen( 'php://output', 'wb' );

                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                        'method' => 'GET',
                        'url' => $this->storageUrl( $auth, $srcCont, $srcRel ),
                        'headers' => $this->authTokenHeaders( $auth )
                                + $this->headersFromParams( $params ),
                        'stream' => $handle,
                ] );

                if ( $rcode >= 200 && $rcode <= 299 ) {
                        // good
                } elseif ( $rcode === 404 ) {
                        $status->fatal( 'backend-fail-stream', $params['src'] );
                } else {
                        $this->onError( $status, __METHOD__, $params, $rerr, $rcode, $rdesc );
                }

                return $status;
        }

        protected function doGetLocalCopyMulti( array $params ) {
                $tmpFiles = [];

                $auth = $this->getAuthentication();

                $ep = array_diff_key( $params, [ '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().
                $reqs = []; // (path => op)

                foreach ( $params['srcs'] as $path ) { // each path in this concurrent batch
                        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                        if ( $srcRel === null || !$auth ) {
                                $tmpFiles[$path] = null;
                                continue;
                        }
                        // 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 ) {
                                        $reqs[$path] = [
                                                'method'  => 'GET',
                                                'url'     => $this->storageUrl( $auth, $srcCont, $srcRel ),
                                                'headers' => $this->authTokenHeaders( $auth )
                                                        + $this->headersFromParams( $params ),
                                                'stream'  => $handle,
                                        ];
                                } else {
                                        $tmpFile = null;
                                }
                        }
                        $tmpFiles[$path] = $tmpFile;
                }

                $isLatest = ( $this->isRGW || !empty( $params['latest'] ) );
                $opts = [ 'maxConnsPerHost' => $params['concurrency'] ];
                $reqs = $this->http->runMulti( $reqs, $opts );
                foreach ( $reqs as $path => $op ) {
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $op['response'];
                        fclose( $op['stream'] ); // close open handle
                        if ( $rcode >= 200 && $rcode <= 299 ) {
                                $size = $tmpFiles[$path] ? $tmpFiles[$path]->getSize() : 0;
                                // Double check that the disk is not full/broken
                                if ( $size != $rhdrs['content-length'] ) {
                                        $tmpFiles[$path] = null;
                                        $rerr = "Got {$size}/{$rhdrs['content-length']} bytes";
                                        $this->onError( null, __METHOD__,
                                                [ 'src' => $path ] + $ep, $rerr, $rcode, $rdesc );
                                }
                                // Set the file stat process cache in passing
                                $stat = $this->getStatFromHeaders( $rhdrs );
                                $stat['latest'] = $isLatest;
                                $this->cheapCache->set( $path, 'stat', $stat );
                        } elseif ( $rcode === 404 ) {
                                $tmpFiles[$path] = false;
                        } else {
                                $tmpFiles[$path] = null;
                                $this->onError( null, __METHOD__,
                                        [ 'src' => $path ] + $ep, $rerr, $rcode, $rdesc );
                        }
                }

                return $tmpFiles;
        }

        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
                        }

                        $auth = $this->getAuthentication();
                        if ( !$auth ) {
                                return null;
                        }

                        $ttl = isset( $params['ttl'] ) ? $params['ttl'] : 86400;
                        $expires = time() + $ttl;

                        if ( $this->swiftTempUrlKey != '' ) {
                                $url = $this->storageUrl( $auth, $srcCont, $srcRel );
                                // Swift wants the signature based on the unencoded object name
                                $contPath = parse_url( $this->storageUrl( $auth, $srcCont ), PHP_URL_PATH );
                                $signature = hash_hmac( 'sha1',
                                        "GET\n{$expires}\n{$contPath}/{$srcRel}",
                                        $this->swiftTempUrlKey
                                );

                                return "{$url}?temp_url_sig={$signature}&temp_url_expires={$expires}";
                        } else { // give S3 API URL for rgw
                                // 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
                                                $this->storageUrl( $auth ) . $spath ),
                                        [
                                                'Signature' => $signature,
                                                'Expires' => $expires,
                                                'AWSAccessKeyId' => $this->rgwS3AccessKey ]
                                );
                        }
                }

                return null;
        }

        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 = [];
                if ( !empty( $params['latest'] ) ) {
                        $hdrs['x-newest'] = 'true';
                }

                return $hdrs;
        }

        /**
         * @param FileBackendStoreOpHandle[] $fileOpHandles
         *
         * @return Status[]
         */
        protected function doExecuteOpHandlesInternal( array $fileOpHandles ) {
                $statuses = [];

                $auth = $this->getAuthentication();
                if ( !$auth ) {
                        foreach ( $fileOpHandles as $index => $fileOpHandle ) {
                                $statuses[$index] = Status::newFatal( 'backend-fail-connect', $this->name );
                        }

                        return $statuses;
                }

                // Split the HTTP requests into stages that can be done concurrently
                $httpReqsByStage = []; // map of (stage => index => HTTP request)
                foreach ( $fileOpHandles as $index => $fileOpHandle ) {
                        $reqs = $fileOpHandle->httpOp;
                        // Convert the 'url' parameter to an actual URL using $auth
                        foreach ( $reqs as $stage => &$req ) {
                                list( $container, $relPath ) = $req['url'];
                                $req['url'] = $this->storageUrl( $auth, $container, $relPath );
                                $req['headers'] = isset( $req['headers'] ) ? $req['headers'] : [];
                                $req['headers'] = $this->authTokenHeaders( $auth ) + $req['headers'];
                                $httpReqsByStage[$stage][$index] = $req;
                        }
                        $statuses[$index] = Status::newGood();
                }

                // Run all requests for the first stage, then the next, and so on
                $reqCount = count( $httpReqsByStage );
                for ( $stage = 0; $stage < $reqCount; ++$stage ) {
                        $httpReqs = $this->http->runMulti( $httpReqsByStage[$stage] );
                        foreach ( $httpReqs as $index => $httpReq ) {
                                // Run the callback for each request of this operation
                                $callback = $fileOpHandles[$index]->callback;
                                call_user_func_array( $callback, [ $httpReq, $statuses[$index] ] );
                                // On failure, abort all remaining requests for this operation
                                // (e.g. abort the DELETE request if the COPY request fails for a move)
                                if ( !$statuses[$index]->isOK() ) {
                                        $stages = count( $fileOpHandles[$index]->httpOp );
                                        for ( $s = ( $stage + 1 ); $s < $stages; ++$s ) {
                                                unset( $httpReqsByStage[$s][$index] );
                                        }
                                }
                        }
                }

                return $statuses;
        }

        /**
         * Set read/write permissions for a Swift container.
         *
         * @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 string $container Resolved Swift container
         * @param array $readGrps 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.
         * @param array $writeGrps 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
         * @return Status
         */
        protected function setContainerAccess( $container, array $readGrps, array $writeGrps ) {
                $status = Status::newGood();
                $auth = $this->getAuthentication();

                if ( !$auth ) {
                        $status->fatal( 'backend-fail-connect', $this->name );

                        return $status;
                }

                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                        'method' => 'POST',
                        'url' => $this->storageUrl( $auth, $container ),
                        'headers' => $this->authTokenHeaders( $auth ) + [
                                'x-container-read' => implode( ',', $readGrps ),
                                'x-container-write' => implode( ',', $writeGrps )
                        ]
                ] );

                if ( $rcode != 204 && $rcode !== 202 ) {
                        $status->fatal( 'backend-fail-internal', $this->name );
                        wfDebugLog( 'SwiftBackend', __METHOD__ . ': unexpected rcode value (' . $rcode . ')' );
                }

                return $status;
        }

        /**
         * Get a Swift container stat array, 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 array|bool|null False on 404, null on failure
         */
        protected function getContainerStat( $container, $bypassCache = false ) {
                $ps = Profiler::instance()->scopedProfileIn( __METHOD__ . "-{$this->name}" );

                if ( $bypassCache ) { // purge cache
                        $this->containerStatCache->clear( $container );
                } elseif ( !$this->containerStatCache->has( $container, 'stat' ) ) {
                        $this->primeContainerCache( [ $container ] ); // check persistent cache
                }
                if ( !$this->containerStatCache->has( $container, 'stat' ) ) {
                        $auth = $this->getAuthentication();
                        if ( !$auth ) {
                                return null;
                        }

                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                                'method' => 'HEAD',
                                'url' => $this->storageUrl( $auth, $container ),
                                'headers' => $this->authTokenHeaders( $auth )
                        ] );

                        if ( $rcode === 204 ) {
                                $stat = [
                                        'count' => $rhdrs['x-container-object-count'],
                                        'bytes' => $rhdrs['x-container-bytes-used']
                                ];
                                if ( $bypassCache ) {
                                        return $stat;
                                } else {
                                        $this->containerStatCache->set( $container, 'stat', $stat ); // cache it
                                        $this->setContainerCache( $container, $stat ); // update persistent cache
                                }
                        } elseif ( $rcode === 404 ) {
                                return false;
                        } else {
                                $this->onError( null, __METHOD__,
                                        [ 'cont' => $container ], $rerr, $rcode, $rdesc );

                                return null;
                        }
                }

                return $this->containerStatCache->get( $container, 'stat' );
        }

        /**
         * Create a Swift container
         *
         * @param string $container Container name
         * @param array $params
         * @return Status
         */
        protected function createContainer( $container, array $params ) {
                $status = Status::newGood();

                $auth = $this->getAuthentication();
                if ( !$auth ) {
                        $status->fatal( 'backend-fail-connect', $this->name );

                        return $status;
                }

                // @see SwiftFileBackend::setContainerAccess()
                if ( empty( $params['noAccess'] ) ) {
                        $readGrps = [ '.r:*', $this->swiftUser ]; // public
                } else {
                        $readGrps = [ $this->swiftUser ]; // private
                }
                $writeGrps = [ $this->swiftUser ]; // sanity

                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                        'method' => 'PUT',
                        'url' => $this->storageUrl( $auth, $container ),
                        'headers' => $this->authTokenHeaders( $auth ) + [
                                'x-container-read' => implode( ',', $readGrps ),
                                'x-container-write' => implode( ',', $writeGrps )
                        ]
                ] );

                if ( $rcode === 201 ) { // new
                        // good
                } elseif ( $rcode === 202 ) { // already there
                        // this shouldn't really happen, but is OK
                } else {
                        $this->onError( $status, __METHOD__, $params, $rerr, $rcode, $rdesc );
                }

                return $status;
        }

        /**
         * Delete a Swift container
         *
         * @param string $container Container name
         * @param array $params
         * @return Status
         */
        protected function deleteContainer( $container, array $params ) {
                $status = Status::newGood();

                $auth = $this->getAuthentication();
                if ( !$auth ) {
                        $status->fatal( 'backend-fail-connect', $this->name );

                        return $status;
                }

                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                        'method' => 'DELETE',
                        'url' => $this->storageUrl( $auth, $container ),
                        'headers' => $this->authTokenHeaders( $auth )
                ] );

                if ( $rcode >= 200 && $rcode <= 299 ) { // deleted
                        $this->containerStatCache->clear( $container ); // purge
                } elseif ( $rcode === 404 ) { // not there
                        // this shouldn't really happen, but is OK
                } elseif ( $rcode === 409 ) { // not empty
                        $this->onError( $status, __METHOD__, $params, $rerr, $rcode, $rdesc ); // race?
                } else {
                        $this->onError( $status, __METHOD__, $params, $rerr, $rcode, $rdesc );
                }

                return $status;
        }

        /**
         * Get a list of objects under a container.
         * Either just the names or a list of stdClass objects with details can be returned.
         *
         * @param string $fullCont
         * @param string $type ('info' for a list of object detail maps, 'names' for names only)
         * @param int $limit
         * @param string|null $after
         * @param string|null $prefix
         * @param string|null $delim
         * @return Status With the list as value
         */
        private function objectListing(
                $fullCont, $type, $limit, $after = null, $prefix = null, $delim = null
        ) {
                $status = Status::newGood();

                $auth = $this->getAuthentication();
                if ( !$auth ) {
                        $status->fatal( 'backend-fail-connect', $this->name );

                        return $status;
                }

                $query = [ 'limit' => $limit ];
                if ( $type === 'info' ) {
                        $query['format'] = 'json';
                }
                if ( $after !== null ) {
                        $query['marker'] = $after;
                }
                if ( $prefix !== null ) {
                        $query['prefix'] = $prefix;
                }
                if ( $delim !== null ) {
                        $query['delimiter'] = $delim;
                }

                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                        'method' => 'GET',
                        'url' => $this->storageUrl( $auth, $fullCont ),
                        'query' => $query,
                        'headers' => $this->authTokenHeaders( $auth )
                ] );

                $params = [ 'cont' => $fullCont, 'prefix' => $prefix, 'delim' => $delim ];
                if ( $rcode === 200 ) { // good
                        if ( $type === 'info' ) {
                                $status->value = FormatJson::decode( trim( $rbody ) );
                        } else {
                                $status->value = explode( "\n", trim( $rbody ) );
                        }
                } elseif ( $rcode === 204 ) {
                        $status->value = []; // empty container
                } elseif ( $rcode === 404 ) {
                        $status->value = []; // no container
                } else {
                        $this->onError( $status, __METHOD__, $params, $rerr, $rcode, $rdesc );
                }

                return $status;
        }

        protected function doPrimeContainerCache( array $containerInfo ) {
                foreach ( $containerInfo as $container => $info ) {
                        $this->containerStatCache->set( $container, 'stat', $info );
                }
        }

        protected function doGetFileStatMulti( array $params ) {
                $stats = [];

                $auth = $this->getAuthentication();

                $reqs = [];
                foreach ( $params['srcs'] as $path ) {
                        list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $path );
                        if ( $srcRel === null ) {
                                $stats[$path] = false;
                                continue; // invalid storage path
                        } elseif ( !$auth ) {
                                $stats[$path] = null;
                                continue;
                        }

                        // (a) Check the container
                        $cstat = $this->getContainerStat( $srcCont );
                        if ( $cstat === false ) {
                                $stats[$path] = false;
                                continue; // ok, nothing to do
                        } elseif ( !is_array( $cstat ) ) {
                                $stats[$path] = null;
                                continue;
                        }

                        $reqs[$path] = [
                                'method'  => 'HEAD',
                                'url'     => $this->storageUrl( $auth, $srcCont, $srcRel ),
                                'headers' => $this->authTokenHeaders( $auth ) + $this->headersFromParams( $params )
                        ];
                }

                $opts = [ 'maxConnsPerHost' => $params['concurrency'] ];
                $reqs = $this->http->runMulti( $reqs, $opts );

                foreach ( $params['srcs'] as $path ) {
                        if ( array_key_exists( $path, $stats ) ) {
                                continue; // some sort of failure above
                        }
                        // (b) Check the file
                        list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $reqs[$path]['response'];
                        if ( $rcode === 200 || $rcode === 204 ) {
                                // Update the object if it is missing some headers
                                $rhdrs = $this->addMissingMetadata( $rhdrs, $path );
                                // Load the stat array from the headers
                                $stat = $this->getStatFromHeaders( $rhdrs );
                                if ( $this->isRGW ) {
                                        $stat['latest'] = true; // strong consistency
                                }
                        } elseif ( $rcode === 404 ) {
                                $stat = false;
                        } else {
                                $stat = null;
                                $this->onError( null, __METHOD__, $params, $rerr, $rcode, $rdesc );
                        }
                        $stats[$path] = $stat;
                }

                return $stats;
        }

        /**
         * @param array $rhdrs
         * @return array
         */
        protected function getStatFromHeaders( array $rhdrs ) {
                // Fetch all of the custom metadata headers
                $metadata = $this->getMetadata( $rhdrs );
                // Fetch all of the custom raw HTTP headers
                $headers = $this->sanitizeHdrs( [ 'headers' => $rhdrs ] );

                return [
                        // Convert various random Swift dates to TS_MW
                        'mtime' => $this->convertSwiftDate( $rhdrs['last-modified'], TS_MW ),
                        // Empty objects actually return no content-length header in Ceph
                        'size'  => isset( $rhdrs['content-length'] ) ? (int)$rhdrs['content-length'] : 0,
                        'sha1'  => isset( $metadata['sha1base36'] ) ? $metadata['sha1base36'] : null,
                        // Note: manifiest ETags are not an MD5 of the file
                        'md5'   => ctype_xdigit( $rhdrs['etag'] ) ? $rhdrs['etag'] : null,
                        'xattr' => [ 'metadata' => $metadata, 'headers' => $headers ]
                ];
        }

        /**
         * @return array|null Credential map
         */
        protected function getAuthentication() {
                if ( $this->authErrorTimestamp !== null ) {
                        if ( ( time() - $this->authErrorTimestamp ) < 60 ) {
                                return null; // failed last attempt; don't bother
                        } else { // actually retry this time
                                $this->authErrorTimestamp = null;
                        }
                }
                // Session keys expire after a while, so we renew them periodically
                $reAuth = ( ( time() - $this->authSessionTimestamp ) > $this->authTTL );
                // Authenticate with proxy and get a session key...
                if ( !$this->authCreds || $reAuth ) {
                        $this->authSessionTimestamp = 0;
                        $cacheKey = $this->getCredsCacheKey( $this->swiftUser );
                        $creds = $this->srvCache->get( $cacheKey ); // credentials
                        // Try to use the credential cache
                        if ( isset( $creds['auth_token'] ) && isset( $creds['storage_url'] ) ) {
                                $this->authCreds = $creds;
                                // Skew the timestamp for worst case to avoid using stale credentials
                                $this->authSessionTimestamp = time() - ceil( $this->authTTL / 2 );
                        } else { // cache miss
                                list( $rcode, $rdesc, $rhdrs, $rbody, $rerr ) = $this->http->run( [
                                        'method' => 'GET',
                                        'url' => "{$this->swiftAuthUrl}/v1.0",
                                        'headers' => [
                                                'x-auth-user' => $this->swiftUser,
                                                'x-auth-key' => $this->swiftKey
                                        ]
                                ] );

                                if ( $rcode >= 200 && $rcode <= 299 ) { // OK
                                        $this->authCreds = [
                                                'auth_token' => $rhdrs['x-auth-token'],
                                                'storage_url' => $rhdrs['x-storage-url']
                                        ];
                                        $this->srvCache->set( $cacheKey, $this->authCreds, ceil( $this->authTTL / 2 ) );
                                        $this->authSessionTimestamp = time();
                                } elseif ( $rcode === 401 ) {
                                        $this->onError( null, __METHOD__, [], "Authentication failed.", $rcode );
                                        $this->authErrorTimestamp = time();

                                        return null;
                                } else {
                                        $this->onError( null, __METHOD__, [], "HTTP return code: $rcode", $rcode );
                                        $this->authErrorTimestamp = time();

                                        return null;
                                }
                        }
                        // Ceph RGW does not use <account> in URLs (OpenStack Swift uses "/v1/<account>")
                        if ( substr( $this->authCreds['storage_url'], -3 ) === '/v1' ) {
                                $this->isRGW = true; // take advantage of strong consistency in Ceph
                        }
                }

                return $this->authCreds;
        }

        /**
         * @param array $creds From getAuthentication()
         * @param string $container
         * @param string $object
         * @return array
         */
        protected function storageUrl( array $creds, $container = null, $object = null ) {
                $parts = [ $creds['storage_url'] ];
                if ( strlen( $container ) ) {
                        $parts[] = rawurlencode( $container );
                }
                if ( strlen( $object ) ) {
                        $parts[] = str_replace( "%2F", "/", rawurlencode( $object ) );
                }

                return implode( '/', $parts );
        }

        /**
         * @param array $creds From getAuthentication()
         * @return array
         */
        protected function authTokenHeaders( array $creds ) {
                return [ 'x-auth-token' => $creds['auth_token'] ];
        }

        /**
         * Get the cache key for a container
         *
         * @param string $username
         * @return string
         */
        private function getCredsCacheKey( $username ) {
                return 'swiftcredentials:' . md5( $username . ':' . $this->swiftAuthUrl );
        }

        /**
         * Log an unexpected exception for this backend.
         * This also sets the Status object to have a fatal error.
         *
         * @param Status|null $status
         * @param string $func
         * @param array $params
         * @param string $err Error string
         * @param int $code HTTP status
         * @param string $desc HTTP status description
         */
        public function onError( $status, $func, array $params, $err = '', $code = 0, $desc = '' ) {
                if ( $status instanceof Status ) {
                        $status->fatal( 'backend-fail-internal', $this->name );
                }
                if ( $code == 401 ) { // possibly a stale token
                        $this->srvCache->delete( $this->getCredsCacheKey( $this->swiftUser ) );
                }
                wfDebugLog( 'SwiftBackend',
                        "HTTP $code ($desc) in '{$func}' (given '" . FormatJson::encode( $params ) . "')" .
                        ( $err ? ": $err" : "" )
                );
        }
}

/**
 * @see FileBackendStoreOpHandle
 */
class SwiftFileOpHandle extends FileBackendStoreOpHandle {
        /** @var array List of Requests for MultiHttpClient */
        public $httpOp;
        /** @var Closure */
        public $callback;

        /**
         * @param SwiftFileBackend $backend
         * @param Closure $callback Function that takes (HTTP request array, status)
         * @param array $httpOp MultiHttpClient op
         */
        public function __construct( SwiftFileBackend $backend, Closure $callback, array $httpOp ) {
                $this->backend = $backend;
                $this->callback = $callback;
                $this->httpOp = $httpOp;
        }
}

/**
 * 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 List of path or (path,stat array) entries */
        protected $bufferIter = [];

        /** @var string List items *after* this path */
        protected $bufferAfter = null;

        /** @var int */
        protected $pos = 0;

        /** @var array */
        protected $params = [];

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

        /** @var string Container name */
        protected $container;

        /** @var string Storage directory */
        protected $dir;

        /** @var int */
        protected $suffixStart;

        const PAGE_SIZE = 9000; // file listing buffer size

        /**
         * @param SwiftFileBackend $backend
         * @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 int
         */
        public function key() {
                return $this->pos;
        }

        /**
         * @see Iterator::next()
         */
        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()
         */
        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 string $after
         * @param int $limit
         * @param array $params
         * @return Traversable|array
         */
        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 );
        }

        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() {
                list( $path, $stat ) = current( $this->bufferIter );
                $relPath = substr( $path, $this->suffixStart );
                if ( is_array( $stat ) ) {
                        $storageDir = rtrim( $this->params['dir'], '/' );
                        $this->backend->loadListingStatInternal( "$storageDir/$relPath", $stat );
                }

                return $relPath;
        }

        protected function pageFromList( $container, $dir, &$after, $limit, array $params ) {
                return $this->backend->getFileListPageInternal( $container, $dir, $after, $limit, $params );
        }
}