includes/filerepo/backend/FileBackendStore.php

   1 <?php
   2 /**
   3  * @file
   4  * @ingroup FileBackend
   5  * @author Aaron Schulz
   6  */
   7
   8 /**
   9  * @brief Base class for all backends using particular storage medium.
  10  *
  11  * This class defines the methods as abstract that subclasses must implement.
  12  * Outside callers should *not* use functions with "Internal" in the name.
  13  *
  14  * The FileBackend operations are implemented using basic functions
  15  * such as storeInternal(), copyInternal(), deleteInternal() and the like.
  16  * This class is also responsible for path resolution and sanitization.
  17  *
  18  * @ingroup FileBackend
  19  * @since 1.19
  20  */
  21 abstract class FileBackendStore extends FileBackend {
  22         /** @var Array Map of paths to small (RAM/disk) cache items */
  23         protected $cache = array(); // (storage path => key => value)
  24         protected $maxCacheSize = 100; // integer; max paths with entries
  25         /** @var Array Map of paths to large (RAM/disk) cache items */
  26         protected $expensiveCache = array(); // (storage path => key => value)
  27         protected $maxExpensiveCacheSize = 10; // integer; max paths with entries
  28
  29         /** @var Array Map of container names to sharding settings */
  30         protected $shardViaHashLevels = array(); // (container name => config array)
  31
  32         protected $maxFileSize = 4294967296; // integer bytes (4GiB)
  33
  34         /**
  35          * Get the maximum allowable file size given backend
  36          * medium restrictions and basic performance constraints.
  37          * Do not call this function from places outside FileBackend and FileOp.
  38          *
  39          * @return integer Bytes
  40          */
  41         final public function maxFileSizeInternal() {
  42                 return $this->maxFileSize;
  43         }
  44
  45         /**
  46          * Check if a file can be created at a given storage path.
  47          * FS backends should check if the parent directory exists and the file is writable.
  48          * Backends using key/value stores should check if the container exists.
  49          *
  50          * @param $storagePath string
  51          * @return bool
  52          */
  53         abstract public function isPathUsableInternal( $storagePath );
  54
  55         /**
  56          * Create a file in the backend with the given contents.
  57          * Do not call this function from places outside FileBackend and FileOp.
  58          *
  59          * $params include:
  60          *     content       : the raw file contents
  61          *     dst           : destination storage path
  62          *     overwrite     : overwrite any file that exists at the destination
  63          *
  64          * @param $params Array
  65          * @return Status
  66          */
  67         final public function createInternal( array $params ) {
  68                 wfProfileIn( __METHOD__ );
  69                 wfProfileIn( __METHOD__ . '-' . $this->name );
  70                 if ( strlen( $params['content'] ) > $this->maxFileSizeInternal() ) {
  71                         $status = Status::newFatal( 'backend-fail-maxsize',
  72                                 $params['dst'], $this->maxFileSizeInternal() );
  73                 } else {
  74                         $status = $this->doCreateInternal( $params );
  75                         $this->clearCache( array( $params['dst'] ) );
  76                 }
  77                 wfProfileOut( __METHOD__ . '-' . $this->name );
  78                 wfProfileOut( __METHOD__ );
  79                 return $status;
  80         }
  81
  82         /**
  83          * @see FileBackendStore::createInternal()
  84          */
  85         abstract protected function doCreateInternal( array $params );
  86
  87         /**
  88          * Store a file into the backend from a file on disk.
  89          * Do not call this function from places outside FileBackend and FileOp.
  90          *
  91          * $params include:
  92          *     src           : source path on disk
  93          *     dst           : destination storage path
  94          *     overwrite     : overwrite any file that exists at the destination
  95          *
  96          * @param $params Array
  97          * @return Status
  98          */
  99         final public function storeInternal( array $params ) {
 100                 wfProfileIn( __METHOD__ );
 101                 wfProfileIn( __METHOD__ . '-' . $this->name );
 102                 if ( filesize( $params['src'] ) > $this->maxFileSizeInternal() ) {
 103                         $status = Status::newFatal( 'backend-fail-store', $params['dst'] );
 104                 } else {
 105                         $status = $this->doStoreInternal( $params );
 106                         $this->clearCache( array( $params['dst'] ) );
 107                 }
 108                 wfProfileOut( __METHOD__ . '-' . $this->name );
 109                 wfProfileOut( __METHOD__ );
 110                 return $status;
 111         }
 112
 113         /**
 114          * @see FileBackendStore::storeInternal()
 115          */
 116         abstract protected function doStoreInternal( array $params );
 117
 118         /**
 119          * Copy a file from one storage path to another in the backend.
 120          * Do not call this function from places outside FileBackend and FileOp.
 121          *
 122          * $params include:
 123          *     src           : source storage path
 124          *     dst           : destination storage path
 125          *     overwrite     : overwrite any file that exists at the destination
 126          *
 127          * @param $params Array
 128          * @return Status
 129          */
 130         final public function copyInternal( array $params ) {
 131                 wfProfileIn( __METHOD__ );
 132                 wfProfileIn( __METHOD__ . '-' . $this->name );
 133                 $status = $this->doCopyInternal( $params );
 134                 $this->clearCache( array( $params['dst'] ) );
 135                 wfProfileOut( __METHOD__ . '-' . $this->name );
 136                 wfProfileOut( __METHOD__ );
 137                 return $status;
 138         }
 139
 140         /**
 141          * @see FileBackendStore::copyInternal()
 142          */
 143         abstract protected function doCopyInternal( array $params );
 144
 145         /**
 146          * Delete a file at the storage path.
 147          * Do not call this function from places outside FileBackend and FileOp.
 148          *
 149          * $params include:
 150          *     src                 : source storage path
 151          *     ignoreMissingSource : do nothing if the source file does not exist
 152          *
 153          * @param $params Array
 154          * @return Status
 155          */
 156         final public function deleteInternal( array $params ) {
 157                 wfProfileIn( __METHOD__ );
 158                 wfProfileIn( __METHOD__ . '-' . $this->name );
 159                 $status = $this->doDeleteInternal( $params );
 160                 $this->clearCache( array( $params['src'] ) );
 161                 wfProfileOut( __METHOD__ . '-' . $this->name );
 162                 wfProfileOut( __METHOD__ );
 163                 return $status;
 164         }
 165
 166         /**
 167          * @see FileBackendStore::deleteInternal()
 168          */
 169         abstract protected function doDeleteInternal( array $params );
 170
 171         /**
 172          * Move a file from one storage path to another in the backend.
 173          * Do not call this function from places outside FileBackend and FileOp.
 174          *
 175          * $params include:
 176          *     src           : source storage path
 177          *     dst           : destination storage path
 178          *     overwrite     : overwrite any file that exists at the destination
 179          *
 180          * @param $params Array
 181          * @return Status
 182          */
 183         final public function moveInternal( array $params ) {
 184                 wfProfileIn( __METHOD__ );
 185                 wfProfileIn( __METHOD__ . '-' . $this->name );
 186                 $status = $this->doMoveInternal( $params );
 187                 $this->clearCache( array( $params['src'], $params['dst'] ) );
 188                 wfProfileOut( __METHOD__ . '-' . $this->name );
 189                 wfProfileOut( __METHOD__ );
 190                 return $status;
 191         }
 192
 193         /**
 194          * @see FileBackendStore::moveInternal()
 195          * @return Status
 196          */
 197         protected function doMoveInternal( array $params ) {
 198                 // Copy source to dest
 199                 $status = $this->copyInternal( $params );
 200                 if ( $status->isOK() ) {
 201                         // Delete source (only fails due to races or medium going down)
 202                         $status->merge( $this->deleteInternal( array( 'src' => $params['src'] ) ) );
 203                         $status->setResult( true, $status->value ); // ignore delete() errors
 204                 }
 205                 return $status;
 206         }
 207
 208         /**
 209          * @see FileBackend::concatenate()
 210          * @return Status
 211          */
 212         final public function concatenate( array $params ) {
 213                 wfProfileIn( __METHOD__ );
 214                 wfProfileIn( __METHOD__ . '-' . $this->name );
 215                 $status = Status::newGood();
 216
 217                 // Try to lock the source files for the scope of this function
 218                 $scopeLockS = $this->getScopedFileLocks( $params['srcs'], LockManager::LOCK_UW, $status );
 219                 if ( $status->isOK() ) {
 220                         // Actually do the concatenation
 221                         $status->merge( $this->doConcatenate( $params ) );
 222                 }
 223
 224                 wfProfileOut( __METHOD__ . '-' . $this->name );
 225                 wfProfileOut( __METHOD__ );
 226                 return $status;
 227         }
 228
 229         /**
 230          * @see FileBackendStore::concatenate()
 231          * @return Status
 232          */
 233         protected function doConcatenate( array $params ) {
 234                 $status = Status::newGood();
 235                 $tmpPath = $params['dst']; // convenience
 236
 237                 // Check that the specified temp file is valid...
 238                 wfSuppressWarnings();
 239                 $ok = ( is_file( $tmpPath ) && !filesize( $tmpPath ) );
 240                 wfRestoreWarnings();
 241                 if ( !$ok ) { // not present or not empty
 242                         $status->fatal( 'backend-fail-opentemp', $tmpPath );
 243                         return $status;
 244                 }
 245
 246                 // Build up the temp file using the source chunks (in order)...
 247                 $tmpHandle = fopen( $tmpPath, 'ab' );
 248                 if ( $tmpHandle === false ) {
 249                         $status->fatal( 'backend-fail-opentemp', $tmpPath );
 250                         return $status;
 251                 }
 252                 foreach ( $params['srcs'] as $virtualSource ) {
 253                         // Get a local FS version of the chunk
 254                         $tmpFile = $this->getLocalReference( array( 'src' => $virtualSource ) );
 255                         if ( !$tmpFile ) {
 256                                 $status->fatal( 'backend-fail-read', $virtualSource );
 257                                 return $status;
 258                         }
 259                         // Get a handle to the local FS version
 260                         $sourceHandle = fopen( $tmpFile->getPath(), 'r' );
 261                         if ( $sourceHandle === false ) {
 262                                 fclose( $tmpHandle );
 263                                 $status->fatal( 'backend-fail-read', $virtualSource );
 264                                 return $status;
 265                         }
 266                         // Append chunk to file (pass chunk size to avoid magic quotes)
 267                         if ( !stream_copy_to_stream( $sourceHandle, $tmpHandle ) ) {
 268                                 fclose( $sourceHandle );
 269                                 fclose( $tmpHandle );
 270                                 $status->fatal( 'backend-fail-writetemp', $tmpPath );
 271                                 return $status;
 272                         }
 273                         fclose( $sourceHandle );
 274                 }
 275                 if ( !fclose( $tmpHandle ) ) {
 276                         $status->fatal( 'backend-fail-closetemp', $tmpPath );
 277                         return $status;
 278                 }
 279
 280                 clearstatcache(); // temp file changed
 281
 282                 return $status;
 283         }
 284
 285         /**
 286          * @see FileBackend::doPrepare()
 287          * @return Status
 288          */
 289         final protected function doPrepare( array $params ) {
 290                 wfProfileIn( __METHOD__ );
 291                 wfProfileIn( __METHOD__ . '-' . $this->name );
 292
 293                 $status = Status::newGood();
 294                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 295                 if ( $dir === null ) {
 296                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
 297                         wfProfileOut( __METHOD__ . '-' . $this->name );
 298                         wfProfileOut( __METHOD__ );
 299                         return $status; // invalid storage path
 300                 }
 301
 302                 if ( $shard !== null ) { // confined to a single container/shard
 303                         $status->merge( $this->doPrepareInternal( $fullCont, $dir, $params ) );
 304                 } else { // directory is on several shards
 305                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 306                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 307                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 308                                 $status->merge( $this->doPrepareInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 309                         }
 310                 }
 311
 312                 wfProfileOut( __METHOD__ . '-' . $this->name );
 313                 wfProfileOut( __METHOD__ );
 314                 return $status;
 315         }
 316
 317         /**
 318          * @see FileBackendStore::doPrepare()
 319          * @return Status
 320          */
 321         protected function doPrepareInternal( $container, $dir, array $params ) {
 322                 return Status::newGood();
 323         }
 324
 325         /**
 326          * @see FileBackend::doSecure()
 327          * @return Status
 328          */
 329         final protected function doSecure( array $params ) {
 330                 wfProfileIn( __METHOD__ );
 331                 wfProfileIn( __METHOD__ . '-' . $this->name );
 332                 $status = Status::newGood();
 333
 334                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 335                 if ( $dir === null ) {
 336                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
 337                         wfProfileOut( __METHOD__ . '-' . $this->name );
 338                         wfProfileOut( __METHOD__ );
 339                         return $status; // invalid storage path
 340                 }
 341
 342                 if ( $shard !== null ) { // confined to a single container/shard
 343                         $status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) );
 344                 } else { // directory is on several shards
 345                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 346                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 347                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 348                                 $status->merge( $this->doSecureInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 349                         }
 350                 }
 351
 352                 wfProfileOut( __METHOD__ . '-' . $this->name );
 353                 wfProfileOut( __METHOD__ );
 354                 return $status;
 355         }
 356
 357         /**
 358          * @see FileBackendStore::doSecure()
 359          * @return Status
 360          */
 361         protected function doSecureInternal( $container, $dir, array $params ) {
 362                 return Status::newGood();
 363         }
 364
 365         /**
 366          * @see FileBackend::doClean()
 367          * @return Status
 368          */
 369         final protected function doClean( array $params ) {
 370                 wfProfileIn( __METHOD__ );
 371                 wfProfileIn( __METHOD__ . '-' . $this->name );
 372                 $status = Status::newGood();
 373
 374                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 375                 if ( $dir === null ) {
 376                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
 377                         wfProfileOut( __METHOD__ . '-' . $this->name );
 378                         wfProfileOut( __METHOD__ );
 379                         return $status; // invalid storage path
 380                 }
 381
 382                 // Attempt to lock this directory...
 383                 $filesLockEx = array( $params['dir'] );
 384                 $scopedLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status );
 385                 if ( !$status->isOK() ) {
 386                         wfProfileOut( __METHOD__ . '-' . $this->name );
 387                         wfProfileOut( __METHOD__ );
 388                         return $status; // abort
 389                 }
 390
 391                 if ( $shard !== null ) { // confined to a single container/shard
 392                         $status->merge( $this->doCleanInternal( $fullCont, $dir, $params ) );
 393                 } else { // directory is on several shards
 394                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 395                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 396                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 397                                 $status->merge( $this->doCleanInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 398                         }
 399                 }
 400
 401                 wfProfileOut( __METHOD__ . '-' . $this->name );
 402                 wfProfileOut( __METHOD__ );
 403                 return $status;
 404         }
 405
 406         /**
 407          * @see FileBackendStore::doClean()
 408          * @return Status
 409          */
 410         protected function doCleanInternal( $container, $dir, array $params ) {
 411                 return Status::newGood();
 412         }
 413
 414         /**
 415          * @see FileBackend::fileExists()
 416          * @return bool|null
 417          */
 418         final public function fileExists( array $params ) {
 419                 wfProfileIn( __METHOD__ );
 420                 wfProfileIn( __METHOD__ . '-' . $this->name );
 421                 $stat = $this->getFileStat( $params );
 422                 wfProfileOut( __METHOD__ . '-' . $this->name );
 423                 wfProfileOut( __METHOD__ );
 424                 return ( $stat === null ) ? null : (bool)$stat; // null => failure
 425         }
 426
 427         /**
 428          * @see FileBackend::getFileTimestamp()
 429          * @return bool
 430          */
 431         final public function getFileTimestamp( array $params ) {
 432                 wfProfileIn( __METHOD__ );
 433                 wfProfileIn( __METHOD__ . '-' . $this->name );
 434                 $stat = $this->getFileStat( $params );
 435                 wfProfileOut( __METHOD__ . '-' . $this->name );
 436                 wfProfileOut( __METHOD__ );
 437                 return $stat ? $stat['mtime'] : false;
 438         }
 439
 440         /**
 441          * @see FileBackend::getFileSize()
 442          * @return bool
 443          */
 444         final public function getFileSize( array $params ) {
 445                 wfProfileIn( __METHOD__ );
 446                 wfProfileIn( __METHOD__ . '-' . $this->name );
 447                 $stat = $this->getFileStat( $params );
 448                 wfProfileOut( __METHOD__ . '-' . $this->name );
 449                 wfProfileOut( __METHOD__ );
 450                 return $stat ? $stat['size'] : false;
 451         }
 452
 453         /**
 454          * @see FileBackend::getFileStat()
 455          * @return bool
 456          */
 457         final public function getFileStat( array $params ) {
 458                 wfProfileIn( __METHOD__ );
 459                 wfProfileIn( __METHOD__ . '-' . $this->name );
 460                 $path = self::normalizeStoragePath( $params['src'] );
 461                 if ( $path === null ) {
 462                         wfProfileOut( __METHOD__ . '-' . $this->name );
 463                         wfProfileOut( __METHOD__ );
 464                         return false; // invalid storage path
 465                 }
 466                 $latest = !empty( $params['latest'] );
 467                 if ( isset( $this->cache[$path]['stat'] ) ) {
 468                         // If we want the latest data, check that this cached
 469                         // value was in fact fetched with the latest available data.
 470                         if ( !$latest || $this->cache[$path]['stat']['latest'] ) {
 471                                 $this->pingCache( $path ); // LRU
 472                                 wfProfileOut( __METHOD__ . '-' . $this->name );
 473                                 wfProfileOut( __METHOD__ );
 474                                 return $this->cache[$path]['stat'];
 475                         }
 476                 }
 477                 wfProfileIn( __METHOD__ . '-miss' );
 478                 wfProfileIn( __METHOD__ . '-miss-' . $this->name );
 479                 $stat = $this->doGetFileStat( $params );
 480                 wfProfileOut( __METHOD__ . '-miss-' . $this->name );
 481                 wfProfileOut( __METHOD__ . '-miss' );
 482                 if ( is_array( $stat ) ) { // don't cache negatives
 483                         $this->trimCache(); // limit memory
 484                         $this->cache[$path]['stat'] = $stat;
 485                         $this->cache[$path]['stat']['latest'] = $latest;
 486                 }
 487                 wfProfileOut( __METHOD__ . '-' . $this->name );
 488                 wfProfileOut( __METHOD__ );
 489                 return $stat;
 490         }
 491
 492         /**
 493          * @see FileBackendStore::getFileStat()
 494          */
 495         abstract protected function doGetFileStat( array $params );
 496
 497         /**
 498          * @see FileBackend::getFileContents()
 499          * @return bool|string
 500          */
 501         public function getFileContents( array $params ) {
 502                 wfProfileIn( __METHOD__ );
 503                 wfProfileIn( __METHOD__ . '-' . $this->name );
 504                 $tmpFile = $this->getLocalReference( $params );
 505                 if ( !$tmpFile ) {
 506                         wfProfileOut( __METHOD__ . '-' . $this->name );
 507                         wfProfileOut( __METHOD__ );
 508                         return false;
 509                 }
 510                 wfSuppressWarnings();
 511                 $data = file_get_contents( $tmpFile->getPath() );
 512                 wfRestoreWarnings();
 513                 wfProfileOut( __METHOD__ . '-' . $this->name );
 514                 wfProfileOut( __METHOD__ );
 515                 return $data;
 516         }
 517
 518         /**
 519          * @see FileBackend::getFileSha1Base36()
 520          * @return bool|string
 521          */
 522         final public function getFileSha1Base36( array $params ) {
 523                 wfProfileIn( __METHOD__ );
 524                 wfProfileIn( __METHOD__ . '-' . $this->name );
 525                 $path = $params['src'];
 526                 if ( isset( $this->cache[$path]['sha1'] ) ) {
 527                         $this->pingCache( $path ); // LRU
 528                         wfProfileOut( __METHOD__ . '-' . $this->name );
 529                         wfProfileOut( __METHOD__ );
 530                         return $this->cache[$path]['sha1'];
 531                 }
 532                 wfProfileIn( __METHOD__ . '-miss' );
 533                 wfProfileIn( __METHOD__ . '-miss-' . $this->name );
 534                 $hash = $this->doGetFileSha1Base36( $params );
 535                 wfProfileOut( __METHOD__ . '-miss-' . $this->name );
 536                 wfProfileOut( __METHOD__ . '-miss' );
 537                 if ( $hash ) { // don't cache negatives
 538                         $this->trimCache(); // limit memory
 539                         $this->cache[$path]['sha1'] = $hash;
 540                 }
 541                 wfProfileOut( __METHOD__ . '-' . $this->name );
 542                 wfProfileOut( __METHOD__ );
 543                 return $hash;
 544         }
 545
 546         /**
 547          * @see FileBackendStore::getFileSha1Base36()
 548          * @return bool
 549          */
 550         protected function doGetFileSha1Base36( array $params ) {
 551                 $fsFile = $this->getLocalReference( $params );
 552                 if ( !$fsFile ) {
 553                         return false;
 554                 } else {
 555                         return $fsFile->getSha1Base36();
 556                 }
 557         }
 558
 559         /**
 560          * @see FileBackend::getFileProps()
 561          * @return Array
 562          */
 563         final public function getFileProps( array $params ) {
 564                 wfProfileIn( __METHOD__ );
 565                 wfProfileIn( __METHOD__ . '-' . $this->name );
 566                 $fsFile = $this->getLocalReference( $params );
 567                 $props = $fsFile ? $fsFile->getProps() : FSFile::placeholderProps();
 568                 wfProfileOut( __METHOD__ . '-' . $this->name );
 569                 wfProfileOut( __METHOD__ );
 570                 return $props;
 571         }
 572
 573         /**
 574          * @see FileBackend::getLocalReference()
 575          * @return TempFSFile|null
 576          */
 577         public function getLocalReference( array $params ) {
 578                 wfProfileIn( __METHOD__ );
 579                 wfProfileIn( __METHOD__ . '-' . $this->name );
 580                 $path = $params['src'];
 581                 if ( isset( $this->expensiveCache[$path]['localRef'] ) ) {
 582                         $this->pingExpensiveCache( $path );
 583                         wfProfileOut( __METHOD__ . '-' . $this->name );
 584                         wfProfileOut( __METHOD__ );
 585                         return $this->expensiveCache[$path]['localRef'];
 586                 }
 587                 $tmpFile = $this->getLocalCopy( $params );
 588                 if ( $tmpFile ) { // don't cache negatives
 589                         $this->trimExpensiveCache(); // limit memory
 590                         $this->expensiveCache[$path]['localRef'] = $tmpFile;
 591                 }
 592                 wfProfileOut( __METHOD__ . '-' . $this->name );
 593                 wfProfileOut( __METHOD__ );
 594                 return $tmpFile;
 595         }
 596
 597         /**
 598          * @see FileBackend::streamFile()
 599          * @return Status
 600          */
 601         final public function streamFile( array $params ) {
 602                 wfProfileIn( __METHOD__ );
 603                 wfProfileIn( __METHOD__ . '-' . $this->name );
 604                 $status = Status::newGood();
 605
 606                 $info = $this->getFileStat( $params );
 607                 if ( !$info ) { // let StreamFile handle the 404
 608                         $status->fatal( 'backend-fail-notexists', $params['src'] );
 609                 }
 610
 611                 // Set output buffer and HTTP headers for stream
 612                 $extraHeaders = isset( $params['headers'] ) ? $params['headers'] : array();
 613                 $res = StreamFile::prepareForStream( $params['src'], $info, $extraHeaders );
 614                 if ( $res == StreamFile::NOT_MODIFIED ) {
 615                         // do nothing; client cache is up to date
 616                 } elseif ( $res == StreamFile::READY_STREAM ) {
 617                         wfProfileIn( __METHOD__ . '-send' );
 618                         wfProfileIn( __METHOD__ . '-send-' . $this->name );
 619                         $status = $this->doStreamFile( $params );
 620                         wfProfileOut( __METHOD__ . '-send-' . $this->name );
 621                         wfProfileOut( __METHOD__ . '-send' );
 622                 } else {
 623                         $status->fatal( 'backend-fail-stream', $params['src'] );
 624                 }
 625
 626                 wfProfileOut( __METHOD__ . '-' . $this->name );
 627                 wfProfileOut( __METHOD__ );
 628                 return $status;
 629         }
 630
 631         /**
 632          * @see FileBackendStore::streamFile()
 633          * @return Status
 634          */
 635         protected function doStreamFile( array $params ) {
 636                 $status = Status::newGood();
 637
 638                 $fsFile = $this->getLocalReference( $params );
 639                 if ( !$fsFile ) {
 640                         $status->fatal( 'backend-fail-stream', $params['src'] );
 641                 } elseif ( !readfile( $fsFile->getPath() ) ) {
 642                         $status->fatal( 'backend-fail-stream', $params['src'] );
 643                 }
 644
 645                 return $status;
 646         }
 647
 648         /**
 649          * @see FileBackend::directoryExists()
 650          * @return bool|null
 651          */
 652         final public function directoryExists( array $params ) {
 653                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 654                 if ( $dir === null ) {
 655                         return false; // invalid storage path
 656                 }
 657                 if ( $shard !== null ) { // confined to a single container/shard
 658                         return $this->doDirectoryExists( $fullCont, $dir, $params );
 659                 } else { // directory is on several shards
 660                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 661                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 662                         $res = false; // response
 663                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 664                                 $exists = $this->doDirectoryExists( "{$fullCont}{$suffix}", $dir, $params );
 665                                 if ( $exists ) {
 666                                         $res = true;
 667                                         break; // found one!
 668                                 } elseif ( $exists === null ) { // error?
 669                                         $res = null; // if we don't find anything, it is indeterminate
 670                                 }
 671                         }
 672                         return $res;
 673                 }
 674         }
 675
 676         /**
 677          * @see FileBackendStore::directoryExists()
 678          *
 679          * @param $container string Resolved container name
 680          * @param $dir string Resolved path relative to container
 681          * @param $params Array
 682          * @return bool|null
 683          */
 684         abstract protected function doDirectoryExists( $container, $dir, array $params );
 685
 686         /**
 687          * @see FileBackend::getDirectoryList()
 688          * @return Array|null|Traversable
 689          */
 690         final public function getDirectoryList( array $params ) {
 691                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 692                 if ( $dir === null ) { // invalid storage path
 693                         return null;
 694                 }
 695                 if ( $shard !== null ) {
 696                         // File listing is confined to a single container/shard
 697                         return $this->getDirectoryListInternal( $fullCont, $dir, $params );
 698                 } else {
 699                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 700                         // File listing spans multiple containers/shards
 701                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 702                         return new FileBackendStoreShardDirIterator( $this,
 703                                 $fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params );
 704                 }
 705         }
 706
 707         /**
 708          * Do not call this function from places outside FileBackend
 709          *
 710          * @see FileBackendStore::getDirectoryList()
 711          *
 712          * @param $container string Resolved container name
 713          * @param $dir string Resolved path relative to container
 714          * @param $params Array
 715          * @return Traversable|Array|null
 716          */
 717         abstract public function getDirectoryListInternal( $container, $dir, array $params );
 718
 719         /**
 720          * @see FileBackend::getFileList()
 721          * @return Array|null|Traversable
 722          */
 723         final public function getFileList( array $params ) {
 724                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 725                 if ( $dir === null ) { // invalid storage path
 726                         return null;
 727                 }
 728                 if ( $shard !== null ) {
 729                         // File listing is confined to a single container/shard
 730                         return $this->getFileListInternal( $fullCont, $dir, $params );
 731                 } else {
 732                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 733                         // File listing spans multiple containers/shards
 734                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 735                         return new FileBackendStoreShardFileIterator( $this,
 736                                 $fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params );
 737                 }
 738         }
 739
 740         /**
 741          * Do not call this function from places outside FileBackend
 742          *
 743          * @see FileBackendStore::getFileList()
 744          *
 745          * @param $container string Resolved container name
 746          * @param $dir string Resolved path relative to container
 747          * @param $params Array
 748          * @return Traversable|Array|null
 749          */
 750         abstract public function getFileListInternal( $container, $dir, array $params );
 751
 752         /**
 753          * Get the list of supported operations and their corresponding FileOp classes.
 754          *
 755          * @return Array
 756          */
 757         protected function supportedOperations() {
 758                 return array(
 759                         'store'       => 'StoreFileOp',
 760                         'copy'        => 'CopyFileOp',
 761                         'move'        => 'MoveFileOp',
 762                         'delete'      => 'DeleteFileOp',
 763                         'create'      => 'CreateFileOp',
 764                         'null'        => 'NullFileOp'
 765                 );
 766         }
 767
 768         /**
 769          * Return a list of FileOp objects from a list of operations.
 770          * Do not call this function from places outside FileBackend.
 771          *
 772          * The result must have the same number of items as the input.
 773          * An exception is thrown if an unsupported operation is requested.
 774          *
 775          * @param $ops Array Same format as doOperations()
 776          * @return Array List of FileOp objects
 777          * @throws MWException
 778          */
 779         final public function getOperationsInternal( array $ops ) {
 780                 $supportedOps = $this->supportedOperations();
 781
 782                 $performOps = array(); // array of FileOp objects
 783                 // Build up ordered array of FileOps...
 784                 foreach ( $ops as $operation ) {
 785                         $opName = $operation['op'];
 786                         if ( isset( $supportedOps[$opName] ) ) {
 787                                 $class = $supportedOps[$opName];
 788                                 // Get params for this operation
 789                                 $params = $operation;
 790                                 // Append the FileOp class
 791                                 $performOps[] = new $class( $this, $params );
 792                         } else {
 793                                 throw new MWException( "Operation '$opName' is not supported." );
 794                         }
 795                 }
 796
 797                 return $performOps;
 798         }
 799
 800         /**
 801          * Get a list of storage paths to lock for a list of operations
 802          * Returns an array with 'sh' (shared) and 'ex' (exclusive) keys,
 803          * each corresponding to a list of storage paths to be locked.
 804          *
 805          * @param $performOps Array List of FileOp objects
 806          * @return Array ('sh' => list of paths, 'ex' => list of paths)
 807          */
 808         final public function getPathsToLockForOpsInternal( array $performOps ) {
 809                 // Build up a list of files to lock...
 810                 $paths = array( 'sh' => array(), 'ex' => array() );
 811                 foreach ( $performOps as $fileOp ) {
 812                         $paths['sh'] = array_merge( $paths['sh'], $fileOp->storagePathsRead() );
 813                         $paths['ex'] = array_merge( $paths['ex'], $fileOp->storagePathsChanged() );
 814                 }
 815                 // Optimization: if doing an EX lock anyway, don't also set an SH one
 816                 $paths['sh'] = array_diff( $paths['sh'], $paths['ex'] );
 817                 // Get a shared lock on the parent directory of each path changed
 818                 $paths['sh'] = array_merge( $paths['sh'], array_map( 'dirname', $paths['ex'] ) );
 819
 820                 return $paths;
 821         }
 822
 823         /**
 824          * @see FileBackend::doOperationsInternal()
 825          * @return Status
 826          */
 827         protected function doOperationsInternal( array $ops, array $opts ) {
 828                 wfProfileIn( __METHOD__ );
 829                 wfProfileIn( __METHOD__ . '-' . $this->name );
 830                 $status = Status::newGood();
 831
 832                 // Build up a list of FileOps...
 833                 $performOps = $this->getOperationsInternal( $ops );
 834
 835                 // Acquire any locks as needed...
 836                 if ( empty( $opts['nonLocking'] ) ) {
 837                         // Build up a list of files to lock...
 838                         $paths = $this->getPathsToLockForOpsInternal( $performOps );
 839                         // Try to lock those files for the scope of this function...
 840                         $scopeLockS = $this->getScopedFileLocks( $paths['sh'], LockManager::LOCK_UW, $status );
 841                         $scopeLockE = $this->getScopedFileLocks( $paths['ex'], LockManager::LOCK_EX, $status );
 842                         if ( !$status->isOK() ) {
 843                                 wfProfileOut( __METHOD__ . '-' . $this->name );
 844                                 wfProfileOut( __METHOD__ );
 845                                 return $status; // abort
 846                         }
 847                 }
 848
 849                 // Clear any cache entries (after locks acquired)
 850                 $this->clearCache();
 851
 852                 // Actually attempt the operation batch...
 853                 $subStatus = FileOp::attemptBatch( $performOps, $opts, $this->fileJournal );
 854
 855                 // Merge errors into status fields
 856                 $status->merge( $subStatus );
 857                 $status->success = $subStatus->success; // not done in merge()
 858
 859                 wfProfileOut( __METHOD__ . '-' . $this->name );
 860                 wfProfileOut( __METHOD__ );
 861                 return $status;
 862         }
 863
 864         /**
 865          * @see FileBackend::clearCache()
 866          */
 867         final public function clearCache( array $paths = null ) {
 868                 if ( is_array( $paths ) ) {
 869                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
 870                         $paths = array_filter( $paths, 'strlen' ); // remove nulls
 871                 }
 872                 if ( $paths === null ) {
 873                         $this->cache = array();
 874                         $this->expensiveCache = array();
 875                 } else {
 876                         foreach ( $paths as $path ) {
 877                                 unset( $this->cache[$path] );
 878                                 unset( $this->expensiveCache[$path] );
 879                         }
 880                 }
 881                 $this->doClearCache( $paths );
 882         }
 883
 884         /**
 885          * Clears any additional stat caches for storage paths
 886          *
 887          * @see FileBackend::clearCache()
 888          *
 889          * @param $paths Array Storage paths (optional)
 890          * @return void
 891          */
 892         protected function doClearCache( array $paths = null ) {}
 893
 894         /**
 895          * Move a cache entry to the top (such as when accessed)
 896          *
 897          * @param $path string Storage path
 898          */
 899         protected function pingCache( $path ) {
 900                 if ( isset( $this->cache[$path] ) ) {
 901                         $tmp = $this->cache[$path];
 902                         unset( $this->cache[$path] );
 903                         $this->cache[$path] = $tmp;
 904                 }
 905         }
 906
 907         /**
 908          * Prune the inexpensive cache if it is too big to add an item
 909          *
 910          * @return void
 911          */
 912         protected function trimCache() {
 913                 if ( count( $this->cache ) >= $this->maxCacheSize ) {
 914                         reset( $this->cache );
 915                         unset( $this->cache[key( $this->cache )] );
 916                 }
 917         }
 918
 919         /**
 920          * Move a cache entry to the top (such as when accessed)
 921          *
 922          * @param $path string Storage path
 923          */
 924         protected function pingExpensiveCache( $path ) {
 925                 if ( isset( $this->expensiveCache[$path] ) ) {
 926                         $tmp = $this->expensiveCache[$path];
 927                         unset( $this->expensiveCache[$path] );
 928                         $this->expensiveCache[$path] = $tmp;
 929                 }
 930         }
 931
 932         /**
 933          * Prune the expensive cache if it is too big to add an item
 934          *
 935          * @return void
 936          */
 937         protected function trimExpensiveCache() {
 938                 if ( count( $this->expensiveCache ) >= $this->maxExpensiveCacheSize ) {
 939                         reset( $this->expensiveCache );
 940                         unset( $this->expensiveCache[key( $this->expensiveCache )] );
 941                 }
 942         }
 943
 944         /**
 945          * Check if a container name is valid.
 946          * This checks for for length and illegal characters.
 947          *
 948          * @param $container string
 949          * @return bool
 950          */
 951         final protected static function isValidContainerName( $container ) {
 952                 // This accounts for Swift and S3 restrictions while leaving room
 953                 // for things like '.xxx' (hex shard chars) or '.seg' (segments).
 954                 // This disallows directory separators or traversal characters.
 955                 // Note that matching strings URL encode to the same string;
 956                 // in Swift, the length restriction is *after* URL encoding.
 957                 return preg_match( '/^[a-z0-9][a-z0-9-_]{0,199}$/i', $container );
 958         }
 959
 960         /**
 961          * Splits a storage path into an internal container name,
 962          * an internal relative file name, and a container shard suffix.
 963          * Any shard suffix is already appended to the internal container name.
 964          * This also checks that the storage path is valid and within this backend.
 965          *
 966          * If the container is sharded but a suffix could not be determined,
 967          * this means that the path can only refer to a directory and can only
 968          * be scanned by looking in all the container shards.
 969          *
 970          * @param $storagePath string
 971          * @return Array (container, path, container suffix) or (null, null, null) if invalid
 972          */
 973         final protected function resolveStoragePath( $storagePath ) {
 974                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
 975                 if ( $backend === $this->name ) { // must be for this backend
 976                         $relPath = self::normalizeContainerPath( $relPath );
 977                         if ( $relPath !== null ) {
 978                                 // Get shard for the normalized path if this container is sharded
 979                                 $cShard = $this->getContainerShard( $container, $relPath );
 980                                 // Validate and sanitize the relative path (backend-specific)
 981                                 $relPath = $this->resolveContainerPath( $container, $relPath );
 982                                 if ( $relPath !== null ) {
 983                                         // Prepend any wiki ID prefix to the container name
 984                                         $container = $this->fullContainerName( $container );
 985                                         if ( self::isValidContainerName( $container ) ) {
 986                                                 // Validate and sanitize the container name (backend-specific)
 987                                                 $container = $this->resolveContainerName( "{$container}{$cShard}" );
 988                                                 if ( $container !== null ) {
 989                                                         return array( $container, $relPath, $cShard );
 990                                                 }
 991                                         }
 992                                 }
 993                         }
 994                 }
 995                 return array( null, null, null );
 996         }
 997
 998         /**
 999          * Like resolveStoragePath() except null values are returned if
1000          * the container is sharded and the shard could not be determined.
1001          *
1002          * @see FileBackendStore::resolveStoragePath()
1003          *
1004          * @param $storagePath string
1005          * @return Array (container, path) or (null, null) if invalid
1006          */
1007         final protected function resolveStoragePathReal( $storagePath ) {
1008                 list( $container, $relPath, $cShard ) = $this->resolveStoragePath( $storagePath );
1009                 if ( $cShard !== null ) {
1010                         return array( $container, $relPath );
1011                 }
1012                 return array( null, null );
1013         }
1014
1015         /**
1016          * Get the container name shard suffix for a given path.
1017          * Any empty suffix means the container is not sharded.
1018          *
1019          * @param $container string Container name
1020          * @param $relStoragePath string Storage path relative to the container
1021          * @return string|null Returns null if shard could not be determined
1022          */
1023         final protected function getContainerShard( $container, $relPath ) {
1024                 list( $levels, $base, $repeat ) = $this->getContainerHashLevels( $container );
1025                 if ( $levels == 1 || $levels == 2 ) {
1026                         // Hash characters are either base 16 or 36
1027                         $char = ( $base == 36 ) ? '[0-9a-z]' : '[0-9a-f]';
1028                         // Get a regex that represents the shard portion of paths.
1029                         // The concatenation of the captures gives us the shard.
1030                         if ( $levels === 1 ) { // 16 or 36 shards per container
1031                                 $hashDirRegex = '(' . $char . ')';
1032                         } else { // 256 or 1296 shards per container
1033                                 if ( $repeat ) { // verbose hash dir format (e.g. "a/ab/abc")
1034                                         $hashDirRegex = $char . '/(' . $char . '{2})';
1035                                 } else { // short hash dir format (e.g. "a/b/c")
1036                                         $hashDirRegex = '(' . $char . ')/(' . $char . ')';
1037                                 }
1038                         }
1039                         // Allow certain directories to be above the hash dirs so as
1040                         // to work with FileRepo (e.g. "archive/a/ab" or "temp/a/ab").
1041                         // They must be 2+ chars to avoid any hash directory ambiguity.
1042                         $m = array();
1043                         if ( preg_match( "!^(?:[^/]{2,}/)*$hashDirRegex(?:/|$)!", $relPath, $m ) ) {
1044                                 return '.' . implode( '', array_slice( $m, 1 ) );
1045                         }
1046                         return null; // failed to match
1047                 }
1048                 return ''; // no sharding
1049         }
1050
1051         /**
1052          * Check if a storage path maps to a single shard.
1053          * Container dirs like "a", where the container shards on "x/xy",
1054          * can reside on several shards. Such paths are tricky to handle.
1055          *
1056          * @param $storagePath string Storage path
1057          * @return bool
1058          */
1059         final public function isSingleShardPathInternal( $storagePath ) {
1060                 list( $c, $r, $shard ) = $this->resolveStoragePath( $storagePath );
1061                 return ( $shard !== null );
1062         }
1063
1064         /**
1065          * Get the sharding config for a container.
1066          * If greater than 0, then all file storage paths within
1067          * the container are required to be hashed accordingly.
1068          *
1069          * @param $container string
1070          * @return Array (integer levels, integer base, repeat flag) or (0, 0, false)
1071          */
1072         final protected function getContainerHashLevels( $container ) {
1073                 if ( isset( $this->shardViaHashLevels[$container] ) ) {
1074                         $config = $this->shardViaHashLevels[$container];
1075                         $hashLevels = (int)$config['levels'];
1076                         if ( $hashLevels == 1 || $hashLevels == 2 ) {
1077                                 $hashBase = (int)$config['base'];
1078                                 if ( $hashBase == 16 || $hashBase == 36 ) {
1079                                         return array( $hashLevels, $hashBase, $config['repeat'] );
1080                                 }
1081                         }
1082                 }
1083                 return array( 0, 0, false ); // no sharding
1084         }
1085
1086         /**
1087          * Get a list of full container shard suffixes for a container
1088          *
1089          * @param $container string
1090          * @return Array
1091          */
1092         final protected function getContainerSuffixes( $container ) {
1093                 $shards = array();
1094                 list( $digits, $base ) = $this->getContainerHashLevels( $container );
1095                 if ( $digits > 0 ) {
1096                         $numShards = pow( $base, $digits );
1097                         for ( $index = 0; $index < $numShards; $index++ ) {
1098                                 $shards[] = '.' . wfBaseConvert( $index, 10, $base, $digits );
1099                         }
1100                 }
1101                 return $shards;
1102         }
1103
1104         /**
1105          * Get the full container name, including the wiki ID prefix
1106          *
1107          * @param $container string
1108          * @return string
1109          */
1110         final protected function fullContainerName( $container ) {
1111                 if ( $this->wikiId != '' ) {
1112                         return "{$this->wikiId}-$container";
1113                 } else {
1114                         return $container;
1115                 }
1116         }
1117
1118         /**
1119          * Resolve a container name, checking if it's allowed by the backend.
1120          * This is intended for internal use, such as encoding illegal chars.
1121          * Subclasses can override this to be more restrictive.
1122          *
1123          * @param $container string
1124          * @return string|null
1125          */
1126         protected function resolveContainerName( $container ) {
1127                 return $container;
1128         }
1129
1130         /**
1131          * Resolve a relative storage path, checking if it's allowed by the backend.
1132          * This is intended for internal use, such as encoding illegal chars or perhaps
1133          * getting absolute paths (e.g. FS based backends). Note that the relative path
1134          * may be the empty string (e.g. the path is simply to the container).
1135          *
1136          * @param $container string Container name
1137          * @param $relStoragePath string Storage path relative to the container
1138          * @return string|null Path or null if not valid
1139          */
1140         protected function resolveContainerPath( $container, $relStoragePath ) {
1141                 return $relStoragePath;
1142         }
1143 }
1144
1145 /**
1146  * FileBackendStore helper function to handle listings that span container shards.
1147  * Do not use this class from places outside of FileBackendStore.
1148  *
1149  * @ingroup FileBackend
1150  */
1151 abstract class FileBackendStoreShardListIterator implements Iterator {
1152         /** @var FileBackendStore */
1153         protected $backend;
1154         /** @var Array */
1155         protected $params;
1156         /** @var Array */
1157         protected $shardSuffixes;
1158         protected $container; // string; full container name
1159         protected $directory; // string; resolved relative path
1160
1161         /** @var Traversable */
1162         protected $iter;
1163         protected $curShard = 0; // integer
1164         protected $pos = 0; // integer
1165
1166         /** @var Array */
1167         protected $multiShardPaths = array(); // (rel path => 1)
1168
1169         /**
1170          * @param $backend FileBackendStore
1171          * @param $container string Full storage container name
1172          * @param $dir string Storage directory relative to container
1173          * @param $suffixes Array List of container shard suffixes
1174          * @param $params Array
1175          */
1176         public function __construct(
1177                 FileBackendStore $backend, $container, $dir, array $suffixes, array $params
1178         ) {
1179                 $this->backend = $backend;
1180                 $this->container = $container;
1181                 $this->directory = $dir;
1182                 $this->shardSuffixes = $suffixes;
1183                 $this->params = $params;
1184         }
1185
1186         /**
1187          * @see Iterator::current()
1188          * @return string|bool String or false
1189          */
1190         public function current() {
1191                 if ( is_array( $this->iter ) ) {
1192                         return current( $this->iter );
1193                 } else {
1194                         return $this->iter->current();
1195                 }
1196         }
1197
1198         /**
1199          * @see Iterator::key()
1200          * @return integer
1201          */
1202         public function key() {
1203                 return $this->pos;
1204         }
1205
1206         /**
1207          * @see Iterator::next()
1208          * @return void
1209          */
1210         public function next() {
1211                 ++$this->pos;
1212                 if ( is_array( $this->iter ) ) {
1213                         next( $this->iter );
1214                 } else {
1215                         $this->iter->next();
1216                 }
1217                 // Filter out items that we already listed
1218                 $this->filterViaNext();
1219                 // Find the next non-empty shard if no elements are left
1220                 $this->nextShardIteratorIfNotValid();
1221         }
1222
1223         /**
1224          * @see Iterator::rewind()
1225          * @return void
1226          */
1227         public function rewind() {
1228                 $this->pos = 0;
1229                 $this->curShard = 0;
1230                 $this->setIteratorFromCurrentShard();
1231                 // Filter out items that we already listed
1232                 $this->filterViaNext();
1233                 // Find the next non-empty shard if this one has no elements
1234                 $this->nextShardIteratorIfNotValid();
1235         }
1236
1237         /**
1238          * @see Iterator::valid()
1239          * @return bool
1240          */
1241         public function valid() {
1242                 if ( $this->iter == null ) {
1243                         return false; // some failure?
1244                 } elseif ( is_array( $this->iter ) ) {
1245                         return ( current( $this->iter ) !== false ); // no paths can have this value
1246                 } else {
1247                         return $this->iter->valid();
1248                 }
1249         }
1250
1251         /**
1252          * Filter out duplicate items by advancing to the next ones
1253          */
1254         protected function filterViaNext() {
1255                 while ( $this->iter->valid() ) {
1256                         $rel = $this->iter->current(); // path relative to given directory
1257                         $path = $this->params['dir'] . "/{$rel}"; // full storage path
1258                         if ( !$this->backend->isSingleShardPathInternal( $path ) ) {
1259                                 // Don't keep listing paths that are on multiple shards
1260                                 if ( isset( $this->multiShardPaths[$rel] ) ) {
1261                                         $this->iter->next(); // we already listed this path
1262                                 } else {
1263                                         $this->multiShardPaths[$rel] = 1;
1264                                         break;
1265                                 }
1266                         }
1267                 }
1268         }
1269
1270         /**
1271          * If the list iterator for this container shard is out of items,
1272          * then move on to the next container that has items.
1273          * If there are none, then it advances to the last container.
1274          */
1275         protected function nextShardIteratorIfNotValid() {
1276                 while ( !$this->valid() ) {
1277                         if ( ++$this->curShard >= count( $this->shardSuffixes ) ) {
1278                                 break; // no more container shards
1279                         }
1280                         $this->setIteratorFromCurrentShard();
1281                 }
1282         }
1283
1284         /**
1285          * Set the list iterator to that of the current container shard
1286          */
1287         protected function setIteratorFromCurrentShard() {
1288                 $suffix = $this->shardSuffixes[$this->curShard];
1289                 $this->iter = $this->listFromShard(
1290                         "{$this->container}{$suffix}", $this->directory, $this->params );
1291         }
1292
1293         /**
1294          * Get the list for a given container shard
1295          *
1296          * @param $container string Resolved container name
1297          * @param $dir string Resolved path relative to container
1298          * @param $params Array
1299          * @return Traversable|Array|null
1300          */
1301         abstract protected function listFromShard( $container, $dir, array $params );
1302 }
1303
1304 /**
1305  * Iterator for listing directories
1306  */
1307 class FileBackendStoreShardDirIterator extends FileBackendStoreShardListIterator {
1308         protected function listFromShard( $container, $dir, array $params ) {
1309                 return $this->backend->getDirectoryListInternal( $container, $dir, $params );
1310         }
1311 }
1312
1313 /**
1314  * Iterator for listing regular files
1315  */
1316 class FileBackendStoreShardFileIterator extends FileBackendStoreShardListIterator {
1317         protected function listFromShard( $container, $dir, array $params ) {
1318                 return $this->backend->getFileListInternal( $container, $dir, $params );
1319         }
1320 }