[FileBackend] Added copy() sanity checks to FSFileBackend.
[lhc/web/wiklou.git] / includes / filerepo / backend / SwiftFileBackend.php
index ca5e129..41d30dd 100644 (file)
@@ -7,24 +7,24 @@
  */
 
 /**
- * Class for an OpenStack Swift based file backend.
+ * @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
+ * 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 FileBackend {
+class SwiftFileBackend extends FileBackendStore {
        /** @var CF_Authentication */
        protected $auth; // Swift authentication handler
        protected $authTTL; // integer seconds
        protected $swiftAnonUser; // string; username to handle unauthenticated requests
-       protected $maxContCacheSize = 20; // integer; max containers with entries
+       protected $maxContCacheSize = 300; // integer; max containers with entries
 
        /** @var CF_Connection */
        protected $conn; // Swift connection handle
@@ -32,38 +32,45 @@ class SwiftFileBackend extends FileBackend {
        protected $connContainers = array(); // container object cache
 
        /**
-        * @see FileBackend::__construct()
+        * @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)
         *    swiftAnonUser      : Swift user used for end-user requests (account:username)
-        *    shardViaHashLevels : Map of container names to the number of hash levels
+        *    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")
         */
        public function __construct( array $config ) {
                parent::__construct( $config );
                // Required settings
                $this->auth = new CF_Authentication(
-                       $config['swiftUser'], 
-                       $config['swiftKey'], 
+                       $config['swiftUser'],
+                       $config['swiftKey'],
                        null, // account; unused
-                       $config['swiftAuthUrl'] 
+                       $config['swiftAuthUrl']
                );
                // Optional settings
                $this->authTTL = isset( $config['swiftAuthTTL'] )
                        ? $config['swiftAuthTTL']
-                       : 120; // some sane number
+                       : 5 * 60; // some sane number
                $this->swiftAnonUser = isset( $config['swiftAnonUser'] )
                        ? $config['swiftAnonUser']
                        : '';
                $this->shardViaHashLevels = isset( $config['shardViaHashLevels'] )
                        ? $config['shardViaHashLevels']
                        : '';
+               // Cache container info to mask latency
+               $this->memCache = wfGetMainCache();
        }
 
        /**
-        * @see FileBackend::resolveContainerPath()
+        * @see FileBackendStore::resolveContainerPath()
+        * @return null
         */
        protected function resolveContainerPath( $container, $relStoragePath ) {
                if ( strlen( urlencode( $relStoragePath ) ) > 1024 ) {
@@ -73,7 +80,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::isPathUsableInternal()
+        * @see FileBackendStore::isPathUsableInternal()
+        * @return bool
         */
        public function isPathUsableInternal( $storagePath ) {
                list( $container, $rel ) = $this->resolveStoragePathReal( $storagePath );
@@ -94,7 +102,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doCopyInternal()
+        * @see FileBackendStore::doCreateInternal()
+        * @return Status
         */
        protected function doCreateInternal( array $params ) {
                $status = Status::newGood();
@@ -109,7 +118,7 @@ class SwiftFileBackend extends FileBackend {
                try {
                        $dContObj = $this->getContainer( $dstCont );
                        if ( empty( $params['overwrite'] ) &&
-                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) ) 
+                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
                        {
                                $status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
                                return $status;
@@ -156,7 +165,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doStoreInternal()
+        * @see FileBackendStore::doStoreInternal()
+        * @return Status
         */
        protected function doStoreInternal( array $params ) {
                $status = Status::newGood();
@@ -171,7 +181,7 @@ class SwiftFileBackend extends FileBackend {
                try {
                        $dContObj = $this->getContainer( $dstCont );
                        if ( empty( $params['overwrite'] ) &&
-                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) ) 
+                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
                        {
                                $status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
                                return $status;
@@ -224,7 +234,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doCopyInternal()
+        * @see FileBackendStore::doCopyInternal()
+        * @return Status
         */
        protected function doCopyInternal( array $params ) {
                $status = Status::newGood();
@@ -246,7 +257,7 @@ class SwiftFileBackend extends FileBackend {
                        $sContObj = $this->getContainer( $srcCont );
                        $dContObj = $this->getContainer( $dstCont );
                        if ( empty( $params['overwrite'] ) &&
-                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) ) 
+                               $this->fileExists( array( 'src' => $params['dst'], 'latest' => 1 ) ) )
                        {
                                $status->fatal( 'backend-fail-alreadyexists', $params['dst'] );
                                return $status;
@@ -279,7 +290,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doDeleteInternal()
+        * @see FileBackendStore::doDeleteInternal()
+        * @return Status
         */
        protected function doDeleteInternal( array $params ) {
                $status = Status::newGood();
@@ -310,7 +322,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doPrepareInternal()
+        * @see FileBackendStore::doPrepareInternal()
+        * @return Status
         */
        protected function doPrepareInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();
@@ -355,7 +368,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doSecureInternal()
+        * @see FileBackendStore::doSecureInternal()
+        * @return Status
         */
        protected function doSecureInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();
@@ -389,7 +403,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doCleanInternal()
+        * @see FileBackendStore::doCleanInternal()
+        * @return Status
         */
        protected function doCleanInternal( $fullCont, $dir, array $params ) {
                $status = Status::newGood();
@@ -433,7 +448,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doFileExists()
+        * @see FileBackendStore::doFileExists()
+        * @return array|bool|null
         */
        protected function doGetFileStat( array $params ) {
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
@@ -445,6 +461,7 @@ class SwiftFileBackend extends FileBackend {
                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 ),
@@ -464,7 +481,37 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackendBase::getFileContents()
+        * Fill in any missing object metadata and save it to Swift
+        *
+        * @param $obj CF_Object
+        * @param $path string Storage path to object
+        * @return bool Success
+        * @throws Exception cloudfiles exceptions
+        */
+       protected function addMissingMetadata( CF_Object $obj, $path ) {
+               if ( isset( $obj->metadata['Sha1base36'] ) ) {
+                       return true; // nothing to do
+               }
+               $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->metadata['Sha1base36'] = $hash;
+                                       $obj->sync_metadata(); // save to Swift
+                                       return true; // success
+                               }
+                       }
+               }
+               $obj->metadata['Sha1base36'] = false;
+               return false; // failed
+       }
+
+       /**
+        * @see FileBackend::getFileContents()
+        * @return bool|null|string
         */
        public function getFileContents( array $params ) {
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
@@ -491,30 +538,136 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::getFileListInternal()
+        * @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 ( InvalidResponseException $e ) {
+               } catch ( Exception $e ) { // some other exception?
+                       $this->logException( $e, __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 );
+               return new SwiftFileBackendFileList( $this, $fullCont, $dir, $params );
        }
 
        /**
         * Do not call this function outside of SwiftFileBackendFileList
-        * 
+        *
         * @param $fullCont string Resolved container name
         * @param $dir string Resolved storage directory with no trailing slash
-        * @param $after string Storage path of file to list items after
+        * @param $after string|null Storage path of file to list items after
         * @param $limit integer Max number of items to list
-        * @return Array
+        * @param $params Array Includes flag for 'topOnly'
+        * @return Array List of relative paths of dirs directly under $dir
+        */
+       public function getDirListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
+               $dirs = array();
+
+               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 dirs
+                                       if ( substr( $object, -1 ) === '/' ) {
+                                               $dirs[] = $object; // directories end in '/'
+                                       }
+                                       $after = $object; // update last item
+                               }
+                       // 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 ) { // file has a parent 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 ( $objectDir > $lastDir ) {
+                                                       $pDir = $objectDir;
+                                                       do { // add dir and all its parent dirs
+                                                               $dirs[] = "{$pDir}/";
+                                                               $pDir = $this->getParentDir( $pDir );
+                                                       } while ( $pDir !== false // sanity
+                                                               && $pDir > $lastDir // not done already
+                                                               && strlen( $pDir ) > strlen( $dir ) // within $dir
+                                                       );
+                                               }
+                                               $lastDir = $objectDir;
+                                       }
+                                       $after = $object; // update last item
+                               }
+                       }
+               } catch ( NoSuchContainerException $e ) {
+               } catch ( InvalidResponseException $e ) {
+               } catch ( Exception $e ) { // some other exception?
+                       $this->logException( $e, __METHOD__, array( 'cont' => $fullCont, 'dir' => $dir ) );
+               }
+
+               return $dirs;
+       }
+
+       protected function getParentDir( $path ) {
+               return ( strpos( $path, '/' ) !== false ) ? dirname( $path ) : false;
+       }
+
+       /**
+        * Do not call this function outside of SwiftFileBackendFileList
+        *
+        * @param $fullCont string Resolved container name
+        * @param $dir string Resolved storage directory with no trailing slash
+        * @param $after string|null Storage path of file to list items after
+        * @param $limit integer Max number of items to list
+        * @param $params Array Includes flag for 'topOnly'
+        * @return Array List of relative paths of files under $dir
         */
-       public function getFileListPageInternal( $fullCont, $dir, $after, $limit ) {
+       public function getFileListPageInternal( $fullCont, $dir, &$after, $limit, array $params ) {
                $files = array();
 
                try {
                        $container = $this->getContainer( $fullCont );
                        $prefix = ( $dir == '' ) ? null : "{$dir}/";
-                       $files = $container->list_objects( $limit, $after, $prefix );
+                       // Non-recursive: only list files right under $dir
+                       if ( !empty( $params['topOnly'] ) ) { // files and dirs
+                               $objects = $container->list_objects( $limit, $after, $prefix, null, '/' );
+                               foreach ( $objects as $object ) {
+                                       if ( substr( $object, -1 ) !== '/' ) {
+                                               $files[] = $object; // directories end in '/'
+                                       }
+                               }
+                       // Recursive: list all files under $dir and its subdirs
+                       } else { // files
+                               $files = $container->list_objects( $limit, $after, $prefix );
+                       }
+                       $after = end( $files ); // update last item
+                       reset( $files ); // reset pointer
                } catch ( NoSuchContainerException $e ) {
-               } catch ( NoSuchObjectException $e ) {
                } catch ( InvalidResponseException $e ) {
                } catch ( Exception $e ) { // some other exception?
                        $this->logException( $e, __METHOD__, array( 'cont' => $fullCont, 'dir' => $dir ) );
@@ -524,9 +677,10 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doGetFileSha1base36()
+        * @see FileBackendStore::doGetFileSha1base36()
+        * @return bool
         */
-       public function doGetFileSha1base36( array $params ) {
+       protected function doGetFileSha1base36( array $params ) {
                $stat = $this->getFileStat( $params );
                if ( $stat ) {
                        return $stat['sha1'];
@@ -536,7 +690,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doStreamFile()
+        * @see FileBackendStore::doStreamFile()
+        * @return Status
         */
        protected function doStreamFile( array $params ) {
                $status = Status::newGood();
@@ -561,8 +716,7 @@ class SwiftFileBackend extends FileBackend {
                }
 
                try {
-                       $output = fopen( 'php://output', 'w' );
-                       // FileBackend::streamFile() already checks existence
+                       $output = fopen( 'php://output', 'wb' );
                        $obj = new CF_Object( $cont, $srcRel, false, false ); // skip HEAD request
                        $obj->stream( $output, $this->headersFromParams( $params ) );
                } catch ( InvalidResponseException $e ) { // 404? connection problem?
@@ -576,7 +730,8 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::getLocalCopy()
+        * @see FileBackendStore::getLocalCopy()
+        * @return null|TempFSFile
         */
        public function getLocalCopy( array $params ) {
                list( $srcCont, $srcRel ) = $this->resolveStoragePathReal( $params['src'] );
@@ -617,13 +772,21 @@ class SwiftFileBackend extends FileBackend {
                return $tmpFile;
        }
 
+       /**
+        * @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(). 
+        * on a FileBackend params array, e.g. that of getLocalCopy().
         * $params is currently only checked for a 'latest' flag.
-        * 
+        *
         * @param $params Array
-        * @return Array 
+        * @return Array
         */
        protected function headersFromParams( array $params ) {
                $hdrs = array();
@@ -649,7 +812,7 @@ class SwiftFileBackend extends FileBackend {
                $url = $creds['storage_url'] . '/' . rawurlencode( $contObj->name );
 
                // Note: 10 second timeout consistent with php-cloudfiles
-               $req = new CurlHttpRequest( $url, array( 'method'  => 'POST', 'timeout' => 10 ) );
+               $req = new CurlHttpRequest( $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 ) );
@@ -660,7 +823,7 @@ class SwiftFileBackend extends FileBackend {
        /**
         * Get a connection to the Swift proxy
         *
-        * @return CF_Connection|false
+        * @return CF_Connection|bool False on failure
         * @throws InvalidResponseException
         */
        protected function getConnection() {
@@ -692,7 +855,7 @@ class SwiftFileBackend extends FileBackend {
        }
 
        /**
-        * @see FileBackend::doClearCache()
+        * @see FileBackendStore::doClearCache()
         */
        protected function doClearCache( array $paths = null ) {
                $this->connContainers = array(); // clear container object cache
@@ -703,23 +866,30 @@ class SwiftFileBackend extends FileBackend {
         * Use $reCache if the file count or byte count is needed.
         *
         * @param $container string Container name
-        * @param $reCache bool Refresh the process cache
+        * @param $bypassCache bool Bypass all caches and load from Swift
         * @return CF_Container
+        * @throws InvalidResponseException
         */
-       protected function getContainer( $container, $reCache = false ) {
+       protected function getContainer( $container, $bypassCache = false ) {
                $conn = $this->getConnection(); // Swift proxy connection
-               if ( $reCache ) {
-                       unset( $this->connContainers[$container] ); // purge cache
+               if ( $bypassCache ) { // purge cache
+                       unset( $this->connContainers[$container] );
+               } elseif ( !isset( $this->connContainers[$container] ) ) {
+                       $this->primeContainerCache( array( $container ) ); // check persistent cache
                }
                if ( !isset( $this->connContainers[$container] ) ) {
                        $contObj = $conn->get_container( $container );
                        // NoSuchContainerException not thrown: container must exist
                        if ( count( $this->connContainers ) >= $this->maxContCacheSize ) { // trim cache?
                                reset( $this->connContainers );
-                               $key = key( $this->connContainers );
-                               unset( $this->connContainers[$key] );
+                               unset( $this->connContainers[key( $this->connContainers )] );
                        }
                        $this->connContainers[$container] = $contObj; // cache it
+                       if ( !$bypassCache ) {
+                               $this->setContainerCache( $container, // update persistent cache
+                                       array( 'bytes' => $contObj->bytes_used, 'count' => $contObj->object_count )
+                               );
+                       }
                }
                return $this->connContainers[$container];
        }
@@ -729,6 +899,7 @@ class SwiftFileBackend extends FileBackend {
         *
         * @param $container string Container name
         * @return CF_Container
+        * @throws InvalidResponseException
         */
        protected function createContainer( $container ) {
                $conn = $this->getConnection(); // Swift proxy connection
@@ -742,6 +913,7 @@ class SwiftFileBackend extends FileBackend {
         *
         * @param $container string Container name
         * @return void
+        * @throws InvalidResponseException
         */
        protected function deleteContainer( $container ) {
                $conn = $this->getConnection(); // Swift proxy connection
@@ -749,9 +921,31 @@ class SwiftFileBackend extends FileBackend {
                unset( $this->connContainers[$container] ); // purge cache
        }
 
+       /**
+        * @see FileBackendStore::doPrimeContainerCache()
+        * @return void
+        */
+       protected function doPrimeContainerCache( array $containerInfo ) {
+               try {
+                       $conn = $this->getConnection(); // Swift proxy connection
+                       foreach ( $containerInfo as $container => $info ) {
+                               $this->connContainers[$container] = new CF_Container(
+                                       $conn->cfs_auth,
+                                       $conn->cfs_http,
+                                       $container,
+                                       $info['count'],
+                                       $info['bytes']
+                               );
+                       }
+               } catch ( InvalidResponseException $e ) {
+               } catch ( Exception $e ) { // some other exception?
+                       $this->logException( $e, __METHOD__, array() );
+               }
+       }
+
        /**
         * Log an unexpected exception for this backend
-        * 
+        *
         * @param $e Exception
         * @param $func string
         * @param $params Array
@@ -759,28 +953,34 @@ class SwiftFileBackend extends FileBackend {
         */
        protected function logException( Exception $e, $func, array $params ) {
                wfDebugLog( 'SwiftBackend',
-                       get_class( $e ) . " in '{$this->name}': '{$func}' with " . serialize( $params ) 
+                       get_class( $e ) . " in '{$func}' (given '" . FormatJson::encode( $params ) . "')" .
+                       ( $e instanceof InvalidResponseException
+                               ? ": {$e->getMessage()}"
+                               : ""
+                       )
                );
        }
 }
 
 /**
- * SwiftFileBackend helper class to page through object listings.
+ * 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
  */
-class SwiftFileBackendFileList implements Iterator {
+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; //
-       protected $dir; // string storage directory
+       protected $backend;
+       protected $container; // string; container name
+       protected $dir; // string; storage directory
        protected $suffixStart; // integer
 
        const PAGE_SIZE = 5000; // file listing buffer size
@@ -789,8 +989,9 @@ class SwiftFileBackendFileList implements Iterator {
         * @param $backend SwiftFileBackend
         * @param $fullCont string Resolved container name
         * @param $dir string Resolved directory relative to container
+        * @param $params Array
         */
-       public function __construct( SwiftFileBackend $backend, $fullCont, $dir ) {
+       public function __construct( SwiftFileBackend $backend, $fullCont, $dir, array $params ) {
                $this->backend = $backend;
                $this->container = $fullCont;
                $this->dir = $dir;
@@ -802,16 +1003,21 @@ class SwiftFileBackendFileList implements Iterator {
                } else { // dir within container
                        $this->suffixStart = strlen( $this->dir ) + 1; // size of "path/to/dir/"
                }
+               $this->params = $params;
        }
 
-       public function current() {
-               return substr( current( $this->bufferIter ), $this->suffixStart );
-       }
-
+       /**
+        * @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( $this->bufferIter );
@@ -819,22 +1025,87 @@ class SwiftFileBackendFileList implements Iterator {
                // Check if there are no files left in this page and
                // advance to the next page if this page was not empty.
                if ( !$this->valid() && count( $this->bufferIter ) ) {
-                       $this->bufferAfter = end( $this->bufferIter );
-                       $this->bufferIter = $this->backend->getFileListPageInternal(
-                               $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE
-                       );
+                       $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->backend->getFileListPageInternal(
-                       $this->container, $this->dir, $this->bufferAfter, self::PAGE_SIZE
-               );
+               $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() {
-               return ( current( $this->bufferIter ) !== false ); // no paths can have this value
+               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 $container string Resolved container name
+        * @param $dir string Resolved path relative to container
+        * @param $after string|null
+        * @param $limit integer
+        * @param $params Array
+        * @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 );
        }
 }