includes/filerepo/backend/FileBackend.php

   1 <?php
   2 /**
   3  * @file
   4  * @ingroup FileBackend
   5  * @author Aaron Schulz
   6  */
   7
   8 /**
   9  * Base class for all file backend classes (including multi-write backends).
  10  * This class defines the methods as abstract that subclasses must implement.
  11  * Outside callers can assume that all backends will have these functions.
  12  *
  13  * All "storage paths" are of the format "mwstore://backend/container/path".
  14  * The paths use UNIX file system (FS) notation, though any particular backend may
  15  * not actually be using a local filesystem. Therefore, the paths are only virtual.
  16  *
  17  * Backend contents are stored under wiki-specific container names by default.
  18  * For legacy reasons, this has no effect for the FS backend class, and per-wiki
  19  * segregation must be done by setting the container paths appropriately.
  20  *
  21  * FS-based backends are somewhat more restrictive due to the existence of real
  22  * directory files; a regular file cannot have the same name as a directory. Other
  23  * backends with virtual directories may not have this limitation. Callers should
  24  * store files in such a way that no files and directories are under the same path.
  25  *
  26  * Methods should avoid throwing exceptions at all costs.
  27  * As a corollary, external dependencies should be kept to a minimum.
  28  *
  29  * @ingroup FileBackend
  30  * @since 1.19
  31  */
  32 abstract class FileBackend {
  33         protected $name; // string; unique backend name
  34         protected $wikiId; // string; unique wiki name
  35         protected $readOnly; // string; read-only explanation message
  36         /** @var LockManager */
  37         protected $lockManager;
  38
  39         /**
  40          * Create a new backend instance from configuration.
  41          * This should only be called from within FileBackendGroup.
  42          *
  43          * $config includes:
  44          *     'name'        : The unique name of this backend.
  45          *     'wikiId'      : Prefix to container names that is unique to this wiki.
  46          *                     This should consist of alphanumberic, '-', and '_' chars.
  47          *     'lockManager' : Registered name of a file lock manager to use.
  48          *     'readOnly'    : Write operations are disallowed if this is a non-empty string.
  49          *                     It should be an explanation for the backend being read-only.
  50          *
  51          * @param $config Array
  52          */
  53         public function __construct( array $config ) {
  54                 $this->name = $config['name'];
  55                 $this->wikiId = isset( $config['wikiId'] )
  56                         ? $config['wikiId']
  57                         : wfWikiID(); // e.g. "my_wiki-en_"
  58                 $this->lockManager = LockManagerGroup::singleton()->get( $config['lockManager'] );
  59                 $this->readOnly = isset( $config['readOnly'] )
  60                         ? (string)$config['readOnly']
  61                         : '';
  62         }
  63
  64         /**
  65          * Get the unique backend name.
  66          * We may have multiple different backends of the same type.
  67          * For example, we can have two Swift backends using different proxies.
  68          *
  69          * @return string
  70          */
  71         final public function getName() {
  72                 return $this->name;
  73         }
  74
  75         /**
  76          * This is the main entry point into the backend for write operations.
  77          * Callers supply an ordered list of operations to perform as a transaction.
  78          * Files will be locked, the stat cache cleared, and then the operations attempted.
  79          * If any serious errors occur, all attempted operations will be rolled back.
  80          *
  81          * $ops is an array of arrays. The outer array holds a list of operations.
  82          * Each inner array is a set of key value pairs that specify an operation.
  83          *
  84          * Supported operations and their parameters:
  85          * a) Create a new file in storage with the contents of a string
  86          *     array(
  87          *         'op'                  => 'create',
  88          *         'dst'                 => <storage path>,
  89          *         'content'             => <string of new file contents>,
  90          *         'overwrite'           => <boolean>,
  91          *         'overwriteSame'       => <boolean>
  92          *     )
  93          * b) Copy a file system file into storage
  94          *     array(
  95          *         'op'                  => 'store',
  96          *         'src'                 => <file system path>,
  97          *         'dst'                 => <storage path>,
  98          *         'overwrite'           => <boolean>,
  99          *         'overwriteSame'       => <boolean>
 100          *     )
 101          * c) Copy a file within storage
 102          *     array(
 103          *         'op'                  => 'copy',
 104          *         'src'                 => <storage path>,
 105          *         'dst'                 => <storage path>,
 106          *         'overwrite'           => <boolean>,
 107          *         'overwriteSame'       => <boolean>
 108          *     )
 109          * d) Move a file within storage
 110          *     array(
 111          *         'op'                  => 'move',
 112          *         'src'                 => <storage path>,
 113          *         'dst'                 => <storage path>,
 114          *         'overwrite'           => <boolean>,
 115          *         'overwriteSame'       => <boolean>
 116          *     )
 117          * e) Delete a file within storage
 118          *     array(
 119          *         'op'                  => 'delete',
 120          *         'src'                 => <storage path>,
 121          *         'ignoreMissingSource' => <boolean>
 122          *     )
 123          * f) Do nothing (no-op)
 124          *     array(
 125          *         'op'                  => 'null',
 126          *     )
 127          *
 128          * Boolean flags for operations (operation-specific):
 129          * 'ignoreMissingSource' : The operation will simply succeed and do
 130          *                         nothing if the source file does not exist.
 131          * 'overwrite'           : Any destination file will be overwritten.
 132          * 'overwriteSame'       : An error will not be given if a file already
 133          *                         exists at the destination that has the same
 134          *                         contents as the new contents to be written there.
 135          *
 136          * $opts is an associative of boolean flags, including:
 137          * 'force'               : Errors that would normally cause a rollback do not.
 138          *                         The remaining operations are still attempted if any fail.
 139          * 'nonLocking'          : No locks are acquired for the operations.
 140          *                         This can increase performance for non-critical writes.
 141          *                         This has no effect unless the 'force' flag is set.
 142          * 'allowStale'          : Don't require the latest available data.
 143          *                         This can increase performance for non-critical writes.
 144          *                         This has no effect unless the 'force' flag is set.
 145          *
 146          * Remarks on locking:
 147          * File system paths given to operations should refer to files that are
 148          * already locked or otherwise safe from modification from other processes.
 149          * Normally these files will be new temp files, which should be adequate.
 150          *
 151          * Return value:
 152          * This returns a Status, which contains all warnings and fatals that occured
 153          * during the operation. The 'failCount', 'successCount', and 'success' members
 154          * will reflect each operation attempted. The status will be "OK" unless any
 155          * of the operations failed and the 'force' parameter was not set.
 156          *
 157          * @param $ops Array List of operations to execute in order
 158          * @param $opts Array Batch operation options
 159          * @return Status
 160          */
 161         final public function doOperations( array $ops, array $opts = array() ) {
 162                 if ( $this->readOnly != '' ) {
 163                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 164                 }
 165                 if ( empty( $opts['force'] ) ) { // sanity
 166                         unset( $opts['nonLocking'] );
 167                         unset( $opts['allowStale'] );
 168                 }
 169                 return $this->doOperationsInternal( $ops, $opts );
 170         }
 171
 172         /**
 173          * @see FileBackend::doOperations()
 174          */
 175         abstract protected function doOperationsInternal( array $ops, array $opts );
 176
 177         /**
 178          * Same as doOperations() except it takes a single operation.
 179          * If you are doing a batch of operations that should either
 180          * all succeed or all fail, then use that function instead.
 181          *
 182          * @see FileBackend::doOperations()
 183          *
 184          * @param $op Array Operation
 185          * @param $opts Array Operation options
 186          * @return Status
 187          */
 188         final public function doOperation( array $op, array $opts = array() ) {
 189                 return $this->doOperations( array( $op ), $opts );
 190         }
 191
 192         /**
 193          * Performs a single create operation.
 194          * This sets $params['op'] to 'create' and passes it to doOperation().
 195          *
 196          * @see FileBackend::doOperation()
 197          *
 198          * @param $params Array Operation parameters
 199          * @param $opts Array Operation options
 200          * @return Status
 201          */
 202         final public function create( array $params, array $opts = array() ) {
 203                 $params['op'] = 'create';
 204                 return $this->doOperation( $params, $opts );
 205         }
 206
 207         /**
 208          * Performs a single store operation.
 209          * This sets $params['op'] to 'store' and passes it to doOperation().
 210          *
 211          * @see FileBackend::doOperation()
 212          *
 213          * @param $params Array Operation parameters
 214          * @param $opts Array Operation options
 215          * @return Status
 216          */
 217         final public function store( array $params, array $opts = array() ) {
 218                 $params['op'] = 'store';
 219                 return $this->doOperation( $params, $opts );
 220         }
 221
 222         /**
 223          * Performs a single copy operation.
 224          * This sets $params['op'] to 'copy' and passes it to doOperation().
 225          *
 226          * @see FileBackend::doOperation()
 227          *
 228          * @param $params Array Operation parameters
 229          * @param $opts Array Operation options
 230          * @return Status
 231          */
 232         final public function copy( array $params, array $opts = array() ) {
 233                 $params['op'] = 'copy';
 234                 return $this->doOperation( $params, $opts );
 235         }
 236
 237         /**
 238          * Performs a single move operation.
 239          * This sets $params['op'] to 'move' and passes it to doOperation().
 240          *
 241          * @see FileBackend::doOperation()
 242          *
 243          * @param $params Array Operation parameters
 244          * @param $opts Array Operation options
 245          * @return Status
 246          */
 247         final public function move( array $params, array $opts = array() ) {
 248                 $params['op'] = 'move';
 249                 return $this->doOperation( $params, $opts );
 250         }
 251
 252         /**
 253          * Performs a single delete operation.
 254          * This sets $params['op'] to 'delete' and passes it to doOperation().
 255          *
 256          * @see FileBackend::doOperation()
 257          *
 258          * @param $params Array Operation parameters
 259          * @param $opts Array Operation options
 260          * @return Status
 261          */
 262         final public function delete( array $params, array $opts = array() ) {
 263                 $params['op'] = 'delete';
 264                 return $this->doOperation( $params, $opts );
 265         }
 266
 267         /**
 268          * Concatenate a list of storage files into a single file system file.
 269          * The target path should refer to a file that is already locked or
 270          * otherwise safe from modification from other processes. Normally,
 271          * the file will be a new temp file, which should be adequate.
 272          * $params include:
 273          *     srcs          : ordered source storage paths (e.g. chunk1, chunk2, ...)
 274          *     dst           : file system path to 0-byte temp file
 275          *
 276          * @param $params Array Operation parameters
 277          * @return Status
 278          */
 279         abstract public function concatenate( array $params );
 280
 281         /**
 282          * Prepare a storage directory for usage.
 283          * This will create any required containers and parent directories.
 284          * Backends using key/value stores only need to create the container.
 285          *
 286          * $params include:
 287          *     dir : storage directory
 288          *
 289          * @param $params Array
 290          * @return Status
 291          */
 292         final public function prepare( array $params ) {
 293                 if ( $this->readOnly != '' ) {
 294                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 295                 }
 296                 return $this->doPrepare( $params );
 297         }
 298
 299         /**
 300          * @see FileBackend::prepare()
 301          */
 302         abstract protected function doPrepare( array $params );
 303
 304         /**
 305          * Take measures to block web access to a storage directory and
 306          * the container it belongs to. FS backends might add .htaccess
 307          * files whereas key/value store backends might restrict container
 308          * access to the auth user that represents end-users in web request.
 309          * This is not guaranteed to actually do anything.
 310          *
 311          * $params include:
 312          *     dir       : storage directory
 313          *     noAccess  : try to deny file access
 314          *     noListing : try to deny file listing
 315          *
 316          * @param $params Array
 317          * @return Status
 318          */
 319         final public function secure( array $params ) {
 320                 if ( $this->readOnly != '' ) {
 321                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 322                 }
 323                 $status = $this->doPrepare( $params ); // dir must exist to restrict it
 324                 if ( $status->isOK() ) {
 325                         $status->merge( $this->doSecure( $params ) );
 326                 }
 327                 return $status;
 328         }
 329
 330         /**
 331          * @see FileBackend::secure()
 332          */
 333         abstract protected function doSecure( array $params );
 334
 335         /**
 336          * Delete a storage directory if it is empty.
 337          * Backends using key/value stores may do nothing unless the directory
 338          * is that of an empty container, in which case it should be deleted.
 339          *
 340          * $params include:
 341          *     dir : storage directory
 342          *
 343          * @param $params Array
 344          * @return Status
 345          */
 346         final public function clean( array $params ) {
 347                 if ( $this->readOnly != '' ) {
 348                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 349                 }
 350                 return $this->doClean( $params );
 351         }
 352
 353         /**
 354          * @see FileBackend::clean()
 355          */
 356         abstract protected function doClean( array $params );
 357
 358         /**
 359          * Check if a file exists at a storage path in the backend.
 360          * This returns false if only a directory exists at the path.
 361          *
 362          * $params include:
 363          *     src    : source storage path
 364          *     latest : use the latest available data
 365          *
 366          * @param $params Array
 367          * @return bool|null Returns null on failure
 368          */
 369         abstract public function fileExists( array $params );
 370
 371         /**
 372          * Get the last-modified timestamp of the file at a storage path.
 373          *
 374          * $params include:
 375          *     src    : source storage path
 376          *     latest : use the latest available data
 377          *
 378          * @param $params Array
 379          * @return string|false TS_MW timestamp or false on failure
 380          */
 381         abstract public function getFileTimestamp( array $params );
 382
 383         /**
 384          * Get the contents of a file at a storage path in the backend.
 385          * This should be avoided for potentially large files.
 386          *
 387          * $params include:
 388          *     src    : source storage path
 389          *     latest : use the latest available data
 390          *
 391          * @param $params Array
 392          * @return string|false Returns false on failure
 393          */
 394         abstract public function getFileContents( array $params );
 395
 396         /**
 397          * Get the size (bytes) of a file at a storage path in the backend.
 398          *
 399          * $params include:
 400          *     src    : source storage path
 401          *     latest : use the latest available data
 402          *
 403          * @param $params Array
 404          * @return integer|false Returns false on failure
 405          */
 406         abstract public function getFileSize( array $params );
 407
 408         /**
 409          * Get quick information about a file at a storage path in the backend.
 410          * If the file does not exist, then this returns false.
 411          * Otherwise, the result is an associative array that includes:
 412          *     mtime  : the last-modified timestamp (TS_MW)
 413          *     size   : the file size (bytes)
 414          * Additional values may be included for internal use only.
 415          *
 416          * $params include:
 417          *     src    : source storage path
 418          *     latest : use the latest available data
 419          *
 420          * @param $params Array
 421          * @return Array|false|null Returns null on failure
 422          */
 423         abstract public function getFileStat( array $params );
 424
 425         /**
 426          * Get a SHA-1 hash of the file at a storage path in the backend.
 427          *
 428          * $params include:
 429          *     src    : source storage path
 430          *     latest : use the latest available data
 431          *
 432          * @param $params Array
 433          * @return string|false Hash string or false on failure
 434          */
 435         abstract public function getFileSha1Base36( array $params );
 436
 437         /**
 438          * Get the properties of the file at a storage path in the backend.
 439          * Returns FSFile::placeholderProps() on failure.
 440          *
 441          * $params include:
 442          *     src    : source storage path
 443          *     latest : use the latest available data
 444          *
 445          * @param $params Array
 446          * @return Array
 447          */
 448         abstract public function getFileProps( array $params );
 449
 450         /**
 451          * Stream the file at a storage path in the backend.
 452          * If the file does not exists, a 404 error will be given.
 453          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
 454          * must be sent if streaming began, while none should be sent otherwise.
 455          * Implementations should flush the output buffer before sending data.
 456          *
 457          * $params include:
 458          *     src     : source storage path
 459          *     headers : additional HTTP headers to send on success
 460          *     latest  : use the latest available data
 461          *
 462          * @param $params Array
 463          * @return Status
 464          */
 465         abstract public function streamFile( array $params );
 466
 467         /**
 468          * Returns a file system file, identical to the file at a storage path.
 469          * The file returned is either:
 470          * a) A local copy of the file at a storage path in the backend.
 471          *    The temporary copy will have the same extension as the source.
 472          * b) An original of the file at a storage path in the backend.
 473          * Temporary files may be purged when the file object falls out of scope.
 474          *
 475          * Write operations should *never* be done on this file as some backends
 476          * may do internal tracking or may be instances of FileBackendMultiWrite.
 477          * In that later case, there are copies of the file that must stay in sync.
 478          * Additionally, further calls to this function may return the same file.
 479          *
 480          * $params include:
 481          *     src    : source storage path
 482          *     latest : use the latest available data
 483          *
 484          * @param $params Array
 485          * @return FSFile|null Returns null on failure
 486          */
 487         abstract public function getLocalReference( array $params );
 488
 489         /**
 490          * Get a local copy on disk of the file at a storage path in the backend.
 491          * The temporary copy will have the same file extension as the source.
 492          * Temporary files may be purged when the file object falls out of scope.
 493          *
 494          * $params include:
 495          *     src    : source storage path
 496          *     latest : use the latest available data
 497          *
 498          * @param $params Array
 499          * @return TempFSFile|null Returns null on failure
 500          */
 501         abstract public function getLocalCopy( array $params );
 502
 503         /**
 504          * Get an iterator to list out all stored files under a storage directory.
 505          * If the directory is of the form "mwstore://container", then all items in
 506          * the container should be listed. If of the form "mwstore://container/dir",
 507          * then all items under that container directory should be listed.
 508          * Results should be storage paths relative to the given directory.
 509          *
 510          * $params include:
 511          *     dir : storage path directory
 512          *
 513          * @return Traversable|Array|null Returns null on failure
 514          */
 515         abstract public function getFileList( array $params );
 516
 517         /**
 518          * Invalidate any in-process file existence and property cache.
 519          * If $paths is given, then only the cache for those files will be cleared.
 520          *
 521          * @param $paths Array Storage paths (optional)
 522          * @return void
 523          */
 524         public function clearCache( array $paths = null ) {}
 525
 526         /**
 527          * Lock the files at the given storage paths in the backend.
 528          * This will either lock all the files or none (on failure).
 529          *
 530          * Callers should consider using getScopedFileLocks() instead.
 531          *
 532          * @param $paths Array Storage paths
 533          * @param $type integer LockManager::LOCK_* constant
 534          * @return Status
 535          */
 536         final public function lockFiles( array $paths, $type ) {
 537                 return $this->lockManager->lock( $paths, $type );
 538         }
 539
 540         /**
 541          * Unlock the files at the given storage paths in the backend.
 542          *
 543          * @param $paths Array Storage paths
 544          * @param $type integer LockManager::LOCK_* constant
 545          * @return Status
 546          */
 547         final public function unlockFiles( array $paths, $type ) {
 548                 return $this->lockManager->unlock( $paths, $type );
 549         }
 550
 551         /**
 552          * Lock the files at the given storage paths in the backend.
 553          * This will either lock all the files or none (on failure).
 554          * On failure, the status object will be updated with errors.
 555          *
 556          * Once the return value goes out scope, the locks will be released and
 557          * the status updated. Unlock fatals will not change the status "OK" value.
 558          *
 559          * @param $paths Array Storage paths
 560          * @param $type integer LockManager::LOCK_* constant
 561          * @param $status Status Status to update on lock/unlock
 562          * @return ScopedLock|null Returns null on failure
 563          */
 564         final public function getScopedFileLocks( array $paths, $type, Status $status ) {
 565                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status );
 566         }
 567
 568         /**
 569          * Check if a given path is a "mwstore://" path.
 570          * This does not do any further validation or any existence checks.
 571          *
 572          * @param $path string
 573          * @return bool
 574          */
 575         final public static function isStoragePath( $path ) {
 576                 return ( strpos( $path, 'mwstore://' ) === 0 );
 577         }
 578
 579         /**
 580          * Split a storage path into a backend name, a container name,
 581          * and a relative file path. The relative path may be the empty string.
 582          * This does not do any path normalization or traversal checks.
 583          *
 584          * @param $storagePath string
 585          * @return Array (backend, container, rel object) or (null, null, null)
 586          */
 587         final public static function splitStoragePath( $storagePath ) {
 588                 if ( self::isStoragePath( $storagePath ) ) {
 589                         // Remove the "mwstore://" prefix and split the path
 590                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
 591                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
 592                                 if ( count( $parts ) == 3 ) {
 593                                         return $parts; // e.g. "backend/container/path"
 594                                 } else {
 595                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
 596                                 }
 597                         }
 598                 }
 599                 return array( null, null, null );
 600         }
 601
 602         /**
 603          * Normalize a storage path by cleaning up directory separators.
 604          * Returns null if the path is not of the format of a valid storage path.
 605          *
 606          * @param $storagePath string
 607          * @return string|null
 608          */
 609         final public static function normalizeStoragePath( $storagePath ) {
 610                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
 611                 if ( $relPath !== null ) { // must be for this backend
 612                         $relPath = self::normalizeContainerPath( $relPath );
 613                         if ( $relPath !== null ) {
 614                                 return ( $relPath != '' )
 615                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
 616                                         : "mwstore://{$backend}/{$container}";
 617                         }
 618                 }
 619                 return null;
 620         }
 621
 622         /**
 623          * Validate and normalize a relative storage path.
 624          * Null is returned if the path involves directory traversal.
 625          * Traversal is insecure for FS backends and broken for others.
 626          *
 627          * @param $path string Storage path relative to a container
 628          * @return string|null
 629          */
 630         final protected static function normalizeContainerPath( $path ) {
 631                 // Normalize directory separators
 632                 $path = strtr( $path, '\\', '/' );
 633                 // Collapse any consecutive directory separators
 634                 $path = preg_replace( '![/]{2,}!', '/', $path );
 635                 // Remove any leading directory separator
 636                 $path = ltrim( $path, '/' );
 637                 // Use the same traversal protection as Title::secureAndSplit()
 638                 if ( strpos( $path, '.' ) !== false ) {
 639                         if (
 640                                 $path === '.' ||
 641                                 $path === '..' ||
 642                                 strpos( $path, './' ) === 0 ||
 643                                 strpos( $path, '../' ) === 0 ||
 644                                 strpos( $path, '/./' ) !== false ||
 645                                 strpos( $path, '/../' ) !== false
 646                         ) {
 647                                 return null;
 648                         }
 649                 }
 650                 return $path;
 651         }
 652
 653         /**
 654          * Get the parent storage directory of a storage path.
 655          * This returns a path like "mwstore://backend/container",
 656          * "mwstore://backend/container/...", or null if there is no parent.
 657          *
 658          * @param $storagePath string
 659          * @return string|null
 660          */
 661         final public static function parentStoragePath( $storagePath ) {
 662                 $storagePath = dirname( $storagePath );
 663                 list( $b, $cont, $rel ) = self::splitStoragePath( $storagePath );
 664                 return ( $rel === null ) ? null : $storagePath;
 665         }
 666
 667         /**
 668          * Get the final extension from a storage or FS path
 669          *
 670          * @param $path string
 671          * @return string
 672          */
 673         final public static function extensionFromPath( $path ) {
 674                 $i = strrpos( $path, '.' );
 675                 return strtolower( $i ? substr( $path, $i + 1 ) : '' );
 676         }
 677 }
 678
 679 /**
 680  * Base class for all single-write backends.
 681  * This class defines the methods as abstract that subclasses must implement.
 682  * Outside callers should *not* use functions with "Internal" in the name.
 683  *
 684  * The FileBackend operations are implemented using basic functions
 685  * such as storeInternal(), copyInternal(), deleteInternal() and the like.
 686  * This class is also responsible for path resolution and sanitization.
 687  *
 688  * @ingroup FileBackend
 689  * @since 1.19
 690  */
 691 abstract class FileBackendStore extends FileBackend {
 692         /** @var Array Map of paths to small (RAM/disk) cache items */
 693         protected $cache = array(); // (storage path => key => value)
 694         protected $maxCacheSize = 100; // integer; max paths with entries
 695         /** @var Array Map of paths to large (RAM/disk) cache items */
 696         protected $expCache = array(); // (storage path => key => value)
 697         protected $maxExpCacheSize = 10; // integer; max paths with entries
 698
 699         /** @var Array */
 700         protected $shardViaHashLevels = array(); // (container name => integer)
 701
 702         protected $maxFileSize = 1000000000; // integer bytes (1GB)
 703
 704         /**
 705          * Get the maximum allowable file size given backend
 706          * medium restrictions and basic performance constraints.
 707          * Do not call this function from places outside FileBackend and FileOp.
 708          *
 709          * @return integer Bytes
 710          */
 711         final public function maxFileSizeInternal() {
 712                 return $this->maxFileSize;
 713         }
 714
 715         /**
 716          * Check if a file can be created at a given storage path.
 717          * FS backends should check if the parent directory exists and the file is writable.
 718          * Backends using key/value stores should check if the container exists.
 719          *
 720          * @param $storagePath string
 721          * @return bool
 722          */
 723         abstract public function isPathUsableInternal( $storagePath );
 724
 725         /**
 726          * Create a file in the backend with the given contents.
 727          * Do not call this function from places outside FileBackend and FileOp.
 728          *
 729          * $params include:
 730          *     content       : the raw file contents
 731          *     dst           : destination storage path
 732          *     overwrite     : overwrite any file that exists at the destination
 733          *
 734          * @param $params Array
 735          * @return Status
 736          */
 737         final public function createInternal( array $params ) {
 738                 wfProfileIn( __METHOD__ );
 739                 if ( strlen( $params['content'] ) > $this->maxFileSizeInternal() ) {
 740                         $status = Status::newFatal( 'backend-fail-create', $params['dst'] );
 741                 } else {
 742                         $status = $this->doCreateInternal( $params );
 743                         $this->clearCache( array( $params['dst'] ) );
 744                 }
 745                 wfProfileOut( __METHOD__ );
 746                 return $status;
 747         }
 748
 749         /**
 750          * @see FileBackendStore::createInternal()
 751          */
 752         abstract protected function doCreateInternal( array $params );
 753
 754         /**
 755          * Store a file into the backend from a file on disk.
 756          * Do not call this function from places outside FileBackend and FileOp.
 757          *
 758          * $params include:
 759          *     src           : source path on disk
 760          *     dst           : destination storage path
 761          *     overwrite     : overwrite any file that exists at the destination
 762          *
 763          * @param $params Array
 764          * @return Status
 765          */
 766         final public function storeInternal( array $params ) {
 767                 wfProfileIn( __METHOD__ );
 768                 if ( filesize( $params['src'] ) > $this->maxFileSizeInternal() ) {
 769                         $status = Status::newFatal( 'backend-fail-store', $params['dst'] );
 770                 } else {
 771                         $status = $this->doStoreInternal( $params );
 772                         $this->clearCache( array( $params['dst'] ) );
 773                 }
 774                 wfProfileOut( __METHOD__ );
 775                 return $status;
 776         }
 777
 778         /**
 779          * @see FileBackendStore::storeInternal()
 780          */
 781         abstract protected function doStoreInternal( array $params );
 782
 783         /**
 784          * Copy a file from one storage path to another in the backend.
 785          * Do not call this function from places outside FileBackend and FileOp.
 786          *
 787          * $params include:
 788          *     src           : source storage path
 789          *     dst           : destination storage path
 790          *     overwrite     : overwrite any file that exists at the destination
 791          *
 792          * @param $params Array
 793          * @return Status
 794          */
 795         final public function copyInternal( array $params ) {
 796                 wfProfileIn( __METHOD__ );
 797                 $status = $this->doCopyInternal( $params );
 798                 $this->clearCache( array( $params['dst'] ) );
 799                 wfProfileOut( __METHOD__ );
 800                 return $status;
 801         }
 802
 803         /**
 804          * @see FileBackendStore::copyInternal()
 805          */
 806         abstract protected function doCopyInternal( array $params );
 807
 808         /**
 809          * Delete a file at the storage path.
 810          * Do not call this function from places outside FileBackend and FileOp.
 811          *
 812          * $params include:
 813          *     src                 : source storage path
 814          *     ignoreMissingSource : do nothing if the source file does not exist
 815          *
 816          * @param $params Array
 817          * @return Status
 818          */
 819         final public function deleteInternal( array $params ) {
 820                 wfProfileIn( __METHOD__ );
 821                 $status = $this->doDeleteInternal( $params );
 822                 $this->clearCache( array( $params['src'] ) );
 823                 wfProfileOut( __METHOD__ );
 824                 return $status;
 825         }
 826
 827         /**
 828          * @see FileBackendStore::deleteInternal()
 829          */
 830         abstract protected function doDeleteInternal( array $params );
 831
 832         /**
 833          * Move a file from one storage path to another in the backend.
 834          * Do not call this function from places outside FileBackend and FileOp.
 835          *
 836          * $params include:
 837          *     src           : source storage path
 838          *     dst           : destination storage path
 839          *     overwrite     : overwrite any file that exists at the destination
 840          *
 841          * @param $params Array
 842          * @return Status
 843          */
 844         final public function moveInternal( array $params ) {
 845                 wfProfileIn( __METHOD__ );
 846                 $status = $this->doMoveInternal( $params );
 847                 $this->clearCache( array( $params['src'], $params['dst'] ) );
 848                 wfProfileOut( __METHOD__ );
 849                 return $status;
 850         }
 851
 852         /**
 853          * @see FileBackendStore::moveInternal()
 854          */
 855         protected function doMoveInternal( array $params ) {
 856                 // Copy source to dest
 857                 $status = $this->copyInternal( $params );
 858                 if ( $status->isOK() ) {
 859                         // Delete source (only fails due to races or medium going down)
 860                         $status->merge( $this->deleteInternal( array( 'src' => $params['src'] ) ) );
 861                         $status->setResult( true, $status->value ); // ignore delete() errors
 862                 }
 863                 return $status;
 864         }
 865
 866         /**
 867          * @see FileBackend::concatenate()
 868          */
 869         final public function concatenate( array $params ) {
 870                 wfProfileIn( __METHOD__ );
 871                 $status = Status::newGood();
 872
 873                 // Try to lock the source files for the scope of this function
 874                 $scopeLockS = $this->getScopedFileLocks( $params['srcs'], LockManager::LOCK_UW, $status );
 875                 if ( $status->isOK() ) {
 876                         // Actually do the concatenation
 877                         $status->merge( $this->doConcatenate( $params ) );
 878                 }
 879
 880                 wfProfileOut( __METHOD__ );
 881                 return $status;
 882         }
 883
 884         /**
 885          * @see FileBackendStore::concatenate()
 886          */
 887         protected function doConcatenate( array $params ) {
 888                 $status = Status::newGood();
 889                 $tmpPath = $params['dst']; // convenience
 890
 891                 // Check that the specified temp file is valid...
 892                 wfSuppressWarnings();
 893                 $ok = ( is_file( $tmpPath ) && !filesize( $tmpPath ) );
 894                 wfRestoreWarnings();
 895                 if ( !$ok ) { // not present or not empty
 896                         $status->fatal( 'backend-fail-opentemp', $tmpPath );
 897                         return $status;
 898                 }
 899
 900                 // Build up the temp file using the source chunks (in order)...
 901                 $tmpHandle = fopen( $tmpPath, 'ab' );
 902                 if ( $tmpHandle === false ) {
 903                         $status->fatal( 'backend-fail-opentemp', $tmpPath );
 904                         return $status;
 905                 }
 906                 foreach ( $params['srcs'] as $virtualSource ) {
 907                         // Get a local FS version of the chunk
 908                         $tmpFile = $this->getLocalReference( array( 'src' => $virtualSource ) );
 909                         if ( !$tmpFile ) {
 910                                 $status->fatal( 'backend-fail-read', $virtualSource );
 911                                 return $status;
 912                         }
 913                         // Get a handle to the local FS version
 914                         $sourceHandle = fopen( $tmpFile->getPath(), 'r' );
 915                         if ( $sourceHandle === false ) {
 916                                 fclose( $tmpHandle );
 917                                 $status->fatal( 'backend-fail-read', $virtualSource );
 918                                 return $status;
 919                         }
 920                         // Append chunk to file (pass chunk size to avoid magic quotes)
 921                         if ( !stream_copy_to_stream( $sourceHandle, $tmpHandle ) ) {
 922                                 fclose( $sourceHandle );
 923                                 fclose( $tmpHandle );
 924                                 $status->fatal( 'backend-fail-writetemp', $tmpPath );
 925                                 return $status;
 926                         }
 927                         fclose( $sourceHandle );
 928                 }
 929                 if ( !fclose( $tmpHandle ) ) {
 930                         $status->fatal( 'backend-fail-closetemp', $tmpPath );
 931                         return $status;
 932                 }
 933
 934                 clearstatcache(); // temp file changed
 935
 936                 return $status;
 937         }
 938
 939         /**
 940          * @see FileBackend::doPrepare()
 941          */
 942         final protected function doPrepare( array $params ) {
 943                 wfProfileIn( __METHOD__ );
 944
 945                 $status = Status::newGood();
 946                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 947                 if ( $dir === null ) {
 948                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
 949                         wfProfileOut( __METHOD__ );
 950                         return $status; // invalid storage path
 951                 }
 952
 953                 if ( $shard !== null ) { // confined to a single container/shard
 954                         $status->merge( $this->doPrepareInternal( $fullCont, $dir, $params ) );
 955                 } else { // directory is on several shards
 956                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 957                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 958                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 959                                 $status->merge( $this->doPrepareInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 960                         }
 961                 }
 962
 963                 wfProfileOut( __METHOD__ );
 964                 return $status;
 965         }
 966
 967         /**
 968          * @see FileBackendStore::doPrepare()
 969          */
 970         protected function doPrepareInternal( $container, $dir, array $params ) {
 971                 return Status::newGood();
 972         }
 973
 974         /**
 975          * @see FileBackend::doSecure()
 976          */
 977         final protected function doSecure( array $params ) {
 978                 wfProfileIn( __METHOD__ );
 979                 $status = Status::newGood();
 980
 981                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
 982                 if ( $dir === null ) {
 983                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
 984                         wfProfileOut( __METHOD__ );
 985                         return $status; // invalid storage path
 986                 }
 987
 988                 if ( $shard !== null ) { // confined to a single container/shard
 989                         $status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) );
 990                 } else { // directory is on several shards
 991                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
 992                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
 993                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
 994                                 $status->merge( $this->doSecureInternal( "{$fullCont}{$suffix}", $dir, $params ) );
 995                         }
 996                 }
 997
 998                 wfProfileOut( __METHOD__ );
 999                 return $status;
1000         }
1001
1002         /**
1003          * @see FileBackendStore::doSecure()
1004          */
1005         protected function doSecureInternal( $container, $dir, array $params ) {
1006                 return Status::newGood();
1007         }
1008
1009         /**
1010          * @see FileBackend::doClean()
1011          */
1012         final protected function doClean( array $params ) {
1013                 wfProfileIn( __METHOD__ );
1014                 $status = Status::newGood();
1015
1016                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
1017                 if ( $dir === null ) {
1018                         $status->fatal( 'backend-fail-invalidpath', $params['dir'] );
1019                         wfProfileOut( __METHOD__ );
1020                         return $status; // invalid storage path
1021                 }
1022
1023                 // Attempt to lock this directory...
1024                 $filesLockEx = array( $params['dir'] );
1025                 $scopedLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status );
1026                 if ( !$status->isOK() ) {
1027                         wfProfileOut( __METHOD__ );
1028                         return $status; // abort
1029                 }
1030
1031                 if ( $shard !== null ) { // confined to a single container/shard
1032                         $status->merge( $this->doCleanInternal( $fullCont, $dir, $params ) );
1033                 } else { // directory is on several shards
1034                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
1035                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
1036                         foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) {
1037                                 $status->merge( $this->doCleanInternal( "{$fullCont}{$suffix}", $dir, $params ) );
1038                         }
1039                 }
1040
1041                 wfProfileOut( __METHOD__ );
1042                 return $status;
1043         }
1044
1045         /**
1046          * @see FileBackendStore::doClean()
1047          */
1048         protected function doCleanInternal( $container, $dir, array $params ) {
1049                 return Status::newGood();
1050         }
1051
1052         /**
1053          * @see FileBackend::fileExists()
1054          */
1055         final public function fileExists( array $params ) {
1056                 wfProfileIn( __METHOD__ );
1057                 $stat = $this->getFileStat( $params );
1058                 wfProfileOut( __METHOD__ );
1059                 return ( $stat === null ) ? null : (bool)$stat; // null => failure
1060         }
1061
1062         /**
1063          * @see FileBackend::getFileTimestamp()
1064          */
1065         final public function getFileTimestamp( array $params ) {
1066                 wfProfileIn( __METHOD__ );
1067                 $stat = $this->getFileStat( $params );
1068                 wfProfileOut( __METHOD__ );
1069                 return $stat ? $stat['mtime'] : false;
1070         }
1071
1072         /**
1073          * @see FileBackend::getFileSize()
1074          */
1075         final public function getFileSize( array $params ) {
1076                 wfProfileIn( __METHOD__ );
1077                 $stat = $this->getFileStat( $params );
1078                 wfProfileOut( __METHOD__ );
1079                 return $stat ? $stat['size'] : false;
1080         }
1081
1082         /**
1083          * @see FileBackend::getFileStat()
1084          */
1085         final public function getFileStat( array $params ) {
1086                 wfProfileIn( __METHOD__ );
1087                 $path = self::normalizeStoragePath( $params['src'] );
1088                 if ( $path === null ) {
1089                         return false; // invalid storage path
1090                 }
1091                 $latest = !empty( $params['latest'] );
1092                 if ( isset( $this->cache[$path]['stat'] ) ) {
1093                         // If we want the latest data, check that this cached
1094                         // value was in fact fetched with the latest available data.
1095                         if ( !$latest || $this->cache[$path]['stat']['latest'] ) {
1096                                 wfProfileOut( __METHOD__ );
1097                                 return $this->cache[$path]['stat'];
1098                         }
1099                 }
1100                 $stat = $this->doGetFileStat( $params );
1101                 if ( is_array( $stat ) ) { // don't cache negatives
1102                         $this->trimCache(); // limit memory
1103                         $this->cache[$path]['stat'] = $stat;
1104                         $this->cache[$path]['stat']['latest'] = $latest;
1105                 }
1106                 wfProfileOut( __METHOD__ );
1107                 return $stat;
1108         }
1109
1110         /**
1111          * @see FileBackendStore::getFileStat()
1112          */
1113         abstract protected function doGetFileStat( array $params );
1114
1115         /**
1116          * @see FileBackend::getFileContents()
1117          */
1118         public function getFileContents( array $params ) {
1119                 wfProfileIn( __METHOD__ );
1120                 $tmpFile = $this->getLocalReference( $params );
1121                 if ( !$tmpFile ) {
1122                         wfProfileOut( __METHOD__ );
1123                         return false;
1124                 }
1125                 wfSuppressWarnings();
1126                 $data = file_get_contents( $tmpFile->getPath() );
1127                 wfRestoreWarnings();
1128                 wfProfileOut( __METHOD__ );
1129                 return $data;
1130         }
1131
1132         /**
1133          * @see FileBackend::getFileSha1Base36()
1134          */
1135         final public function getFileSha1Base36( array $params ) {
1136                 wfProfileIn( __METHOD__ );
1137                 $path = $params['src'];
1138                 if ( isset( $this->cache[$path]['sha1'] ) ) {
1139                         wfProfileOut( __METHOD__ );
1140                         return $this->cache[$path]['sha1'];
1141                 }
1142                 $hash = $this->doGetFileSha1Base36( $params );
1143                 if ( $hash ) { // don't cache negatives
1144                         $this->trimCache(); // limit memory
1145                         $this->cache[$path]['sha1'] = $hash;
1146                 }
1147                 wfProfileOut( __METHOD__ );
1148                 return $hash;
1149         }
1150
1151         /**
1152          * @see FileBackendStore::getFileSha1Base36()
1153          */
1154         protected function doGetFileSha1Base36( array $params ) {
1155                 $fsFile = $this->getLocalReference( $params );
1156                 if ( !$fsFile ) {
1157                         return false;
1158                 } else {
1159                         return $fsFile->getSha1Base36();
1160                 }
1161         }
1162
1163         /**
1164          * @see FileBackend::getFileProps()
1165          */
1166         final public function getFileProps( array $params ) {
1167                 wfProfileIn( __METHOD__ );
1168                 $fsFile = $this->getLocalReference( $params );
1169                 $props = $fsFile ? $fsFile->getProps() : FSFile::placeholderProps();
1170                 wfProfileOut( __METHOD__ );
1171                 return $props;
1172         }
1173
1174         /**
1175          * @see FileBackend::getLocalReference()
1176          */
1177         public function getLocalReference( array $params ) {
1178                 wfProfileIn( __METHOD__ );
1179                 $path = $params['src'];
1180                 if ( isset( $this->expCache[$path]['localRef'] ) ) {
1181                         wfProfileOut( __METHOD__ );
1182                         return $this->expCache[$path]['localRef'];
1183                 }
1184                 $tmpFile = $this->getLocalCopy( $params );
1185                 if ( $tmpFile ) { // don't cache negatives
1186                         $this->trimExpCache(); // limit memory
1187                         $this->expCache[$path]['localRef'] = $tmpFile;
1188                 }
1189                 wfProfileOut( __METHOD__ );
1190                 return $tmpFile;
1191         }
1192
1193         /**
1194          * @see FileBackend::streamFile()
1195          */
1196         final public function streamFile( array $params ) {
1197                 wfProfileIn( __METHOD__ );
1198                 $status = Status::newGood();
1199
1200                 $info = $this->getFileStat( $params );
1201                 if ( !$info ) { // let StreamFile handle the 404
1202                         $status->fatal( 'backend-fail-notexists', $params['src'] );
1203                 }
1204
1205                 // Set output buffer and HTTP headers for stream
1206                 $extraHeaders = $params['headers'] ? $params['headers'] : array();
1207                 $res = StreamFile::prepareForStream( $params['src'], $info, $extraHeaders );
1208                 if ( $res == StreamFile::NOT_MODIFIED ) {
1209                         // do nothing; client cache is up to date
1210                 } elseif ( $res == StreamFile::READY_STREAM ) {
1211                         $status = $this->doStreamFile( $params );
1212                 } else {
1213                         $status->fatal( 'backend-fail-stream', $params['src'] );
1214                 }
1215
1216                 wfProfileOut( __METHOD__ );
1217                 return $status;
1218         }
1219
1220         /**
1221          * @see FileBackendStore::streamFile()
1222          */
1223         protected function doStreamFile( array $params ) {
1224                 $status = Status::newGood();
1225
1226                 $fsFile = $this->getLocalReference( $params );
1227                 if ( !$fsFile ) {
1228                         $status->fatal( 'backend-fail-stream', $params['src'] );
1229                 } elseif ( !readfile( $fsFile->getPath() ) ) {
1230                         $status->fatal( 'backend-fail-stream', $params['src'] );
1231                 }
1232
1233                 return $status;
1234         }
1235
1236         /**
1237          * @see FileBackend::getFileList()
1238          */
1239         final public function getFileList( array $params ) {
1240                 list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] );
1241                 if ( $dir === null ) { // invalid storage path
1242                         return null;
1243                 }
1244                 if ( $shard !== null ) {
1245                         // File listing is confined to a single container/shard
1246                         return $this->getFileListInternal( $fullCont, $dir, $params );
1247                 } else {
1248                         wfDebug( __METHOD__ . ": iterating over all container shards.\n" );
1249                         // File listing spans multiple containers/shards
1250                         list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] );
1251                         return new FileBackendStoreShardListIterator( $this,
1252                                 $fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params );
1253                 }
1254         }
1255
1256         /**
1257          * Do not call this function from places outside FileBackend
1258          *
1259          * @see FileBackendStore::getFileList()
1260          *
1261          * @param $container string Resolved container name
1262          * @param $dir string Resolved path relative to container
1263          * @param $params Array
1264          * @return Traversable|Array|null
1265          */
1266         abstract public function getFileListInternal( $container, $dir, array $params );
1267
1268         /**
1269          * Get the list of supported operations and their corresponding FileOp classes.
1270          *
1271          * @return Array
1272          */
1273         protected function supportedOperations() {
1274                 return array(
1275                         'store'       => 'StoreFileOp',
1276                         'copy'        => 'CopyFileOp',
1277                         'move'        => 'MoveFileOp',
1278                         'delete'      => 'DeleteFileOp',
1279                         'create'      => 'CreateFileOp',
1280                         'null'        => 'NullFileOp'
1281                 );
1282         }
1283
1284         /**
1285          * Return a list of FileOp objects from a list of operations.
1286          * Do not call this function from places outside FileBackend.
1287          *
1288          * The result must have the same number of items as the input.
1289          * An exception is thrown if an unsupported operation is requested.
1290          *
1291          * @param $ops Array Same format as doOperations()
1292          * @return Array List of FileOp objects
1293          * @throws MWException
1294          */
1295         final public function getOperations( array $ops ) {
1296                 $supportedOps = $this->supportedOperations();
1297
1298                 $performOps = array(); // array of FileOp objects
1299                 // Build up ordered array of FileOps...
1300                 foreach ( $ops as $operation ) {
1301                         $opName = $operation['op'];
1302                         if ( isset( $supportedOps[$opName] ) ) {
1303                                 $class = $supportedOps[$opName];
1304                                 // Get params for this operation
1305                                 $params = $operation;
1306                                 // Append the FileOp class
1307                                 $performOps[] = new $class( $this, $params );
1308                         } else {
1309                                 throw new MWException( "Operation `$opName` is not supported." );
1310                         }
1311                 }
1312
1313                 return $performOps;
1314         }
1315
1316         /**
1317          * @see FileBackend::doOperationsInternal()
1318          */
1319         protected function doOperationsInternal( array $ops, array $opts ) {
1320                 wfProfileIn( __METHOD__ );
1321                 $status = Status::newGood();
1322
1323                 // Build up a list of FileOps...
1324                 $performOps = $this->getOperations( $ops );
1325
1326                 // Acquire any locks as needed...
1327                 if ( empty( $opts['nonLocking'] ) ) {
1328                         // Build up a list of files to lock...
1329                         $filesLockEx = $filesLockSh = array();
1330                         foreach ( $performOps as $fileOp ) {
1331                                 $filesLockSh = array_merge( $filesLockSh, $fileOp->storagePathsRead() );
1332                                 $filesLockEx = array_merge( $filesLockEx, $fileOp->storagePathsChanged() );
1333                         }
1334                         // Optimization: if doing an EX lock anyway, don't also set an SH one
1335                         $filesLockSh = array_diff( $filesLockSh, $filesLockEx );
1336                         // Get a shared lock on the parent directory of each path changed
1337                         $filesLockSh = array_merge( $filesLockSh, array_map( 'dirname', $filesLockEx ) );
1338                         // Try to lock those files for the scope of this function...
1339                         $scopeLockS = $this->getScopedFileLocks( $filesLockSh, LockManager::LOCK_UW, $status );
1340                         $scopeLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status );
1341                         if ( !$status->isOK() ) {
1342                                 wfProfileOut( __METHOD__ );
1343                                 return $status; // abort
1344                         }
1345                 }
1346
1347                 // Clear any cache entries (after locks acquired)
1348                 $this->clearCache();
1349
1350                 // Actually attempt the operation batch...
1351                 $subStatus = FileOp::attemptBatch( $performOps, $opts );
1352
1353                 // Merge errors into status fields
1354                 $status->merge( $subStatus );
1355                 $status->success = $subStatus->success; // not done in merge()
1356
1357                 wfProfileOut( __METHOD__ );
1358                 return $status;
1359         }
1360
1361         /**
1362          * @see FileBackend::clearCache()
1363          */
1364         final public function clearCache( array $paths = null ) {
1365                 if ( is_array( $paths ) ) {
1366                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1367                         $paths = array_filter( $paths, 'strlen' ); // remove nulls
1368                 }
1369                 if ( $paths === null ) {
1370                         $this->cache = array();
1371                         $this->expCache = array();
1372                 } else {
1373                         foreach ( $paths as $path ) {
1374                                 unset( $this->cache[$path] );
1375                                 unset( $this->expCache[$path] );
1376                         }
1377                 }
1378                 $this->doClearCache( $paths );
1379         }
1380
1381         /**
1382          * Clears any additional stat caches for storage paths
1383          *
1384          * @see FileBackend::clearCache()
1385          *
1386          * @param $paths Array Storage paths (optional)
1387          * @return void
1388          */
1389         protected function doClearCache( array $paths = null ) {}
1390
1391         /**
1392          * Prune the inexpensive cache if it is too big to add an item
1393          *
1394          * @return void
1395          */
1396         protected function trimCache() {
1397                 if ( count( $this->cache ) >= $this->maxCacheSize ) {
1398                         reset( $this->cache );
1399                         unset( $this->cache[key( $this->cache )] );
1400                 }
1401         }
1402
1403         /**
1404          * Prune the expensive cache if it is too big to add an item
1405          *
1406          * @return void
1407          */
1408         protected function trimExpCache() {
1409                 if ( count( $this->expCache ) >= $this->maxExpCacheSize ) {
1410                         reset( $this->expCache );
1411                         unset( $this->expCache[key( $this->expCache )] );
1412                 }
1413         }
1414
1415         /**
1416          * Check if a container name is valid.
1417          * This checks for for length and illegal characters.
1418          *
1419          * @param $container string
1420          * @return bool
1421          */
1422         final protected static function isValidContainerName( $container ) {
1423                 // This accounts for Swift and S3 restrictions while leaving room
1424                 // for things like '.xxx' (hex shard chars) or '.seg' (segments).
1425                 // This disallows directory separators or traversal characters.
1426                 // Note that matching strings URL encode to the same string;
1427                 // in Swift, the length restriction is *after* URL encoding.
1428                 return preg_match( '/^[a-z0-9][a-z0-9-_]{0,199}$/i', $container );
1429         }
1430
1431         /**
1432          * Splits a storage path into an internal container name,
1433          * an internal relative file name, and a container shard suffix.
1434          * Any shard suffix is already appended to the internal container name.
1435          * This also checks that the storage path is valid and within this backend.
1436          *
1437          * If the container is sharded but a suffix could not be determined,
1438          * this means that the path can only refer to a directory and can only
1439          * be scanned by looking in all the container shards.
1440          *
1441          * @param $storagePath string
1442          * @return Array (container, path, container suffix) or (null, null, null) if invalid
1443          */
1444         final protected function resolveStoragePath( $storagePath ) {
1445                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1446                 if ( $backend === $this->name ) { // must be for this backend
1447                         $relPath = self::normalizeContainerPath( $relPath );
1448                         if ( $relPath !== null ) {
1449                                 // Get shard for the normalized path if this container is sharded
1450                                 $cShard = $this->getContainerShard( $container, $relPath );
1451                                 // Validate and sanitize the relative path (backend-specific)
1452                                 $relPath = $this->resolveContainerPath( $container, $relPath );
1453                                 if ( $relPath !== null ) {
1454                                         // Prepend any wiki ID prefix to the container name
1455                                         $container = $this->fullContainerName( $container );
1456                                         if ( self::isValidContainerName( $container ) ) {
1457                                                 // Validate and sanitize the container name (backend-specific)
1458                                                 $container = $this->resolveContainerName( "{$container}{$cShard}" );
1459                                                 if ( $container !== null ) {
1460                                                         return array( $container, $relPath, $cShard );
1461                                                 }
1462                                         }
1463                                 }
1464                         }
1465                 }
1466                 return array( null, null, null );
1467         }
1468
1469         /**
1470          * Like resolveStoragePath() except null values are returned if
1471          * the container is sharded and the shard could not be determined.
1472          *
1473          * @see FileBackendStore::resolveStoragePath()
1474          *
1475          * @param $storagePath string
1476          * @return Array (container, path) or (null, null) if invalid
1477          */
1478         final protected function resolveStoragePathReal( $storagePath ) {
1479                 list( $container, $relPath, $cShard ) = $this->resolveStoragePath( $storagePath );
1480                 if ( $cShard !== null ) {
1481                         return array( $container, $relPath );
1482                 }
1483                 return array( null, null );
1484         }
1485
1486         /**
1487          * Get the container name shard suffix for a given path.
1488          * Any empty suffix means the container is not sharded.
1489          *
1490          * @param $container string Container name
1491          * @param $relStoragePath string Storage path relative to the container
1492          * @return string|null Returns null if shard could not be determined
1493          */
1494         final protected function getContainerShard( $container, $relPath ) {
1495                 $hashLevels = $this->getContainerHashLevels( $container );
1496                 if ( $hashLevels === 1 ) { // 16 shards per container
1497                         $hashDirRegex = '(?P<shard>[0-9a-f])';
1498                 } elseif ( $hashLevels === 2 ) { // 256 shards per container
1499                         $hashDirRegex = '[0-9a-f]/(?P<shard>[0-9a-f]{2})';
1500                 } else {
1501                         return ''; // no sharding
1502                 }
1503                 // Allow certain directories to be above the hash dirs so as
1504                 // to work with FileRepo (e.g. "archive/a/ab" or "temp/a/ab").
1505                 // They must be 2+ chars to avoid any hash directory ambiguity.
1506                 $m = array();
1507                 if ( preg_match( "!^(?:[^/]{2,}/)*$hashDirRegex(?:/|$)!", $relPath, $m ) ) {
1508                         return '.' . $m['shard'];
1509                 }
1510                 return null; // failed to match
1511         }
1512
1513         /**
1514          * Get the number of hash levels for a container.
1515          * If greater than 0, then all file storage paths within
1516          * the container are required to be hashed accordingly.
1517          *
1518          * @param $container string
1519          * @return integer
1520          */
1521         final protected function getContainerHashLevels( $container ) {
1522                 if ( isset( $this->shardViaHashLevels[$container] ) ) {
1523                         $hashLevels = (int)$this->shardViaHashLevels[$container];
1524                         if ( $hashLevels >= 0 && $hashLevels <= 2 ) {
1525                                 return $hashLevels;
1526                         }
1527                 }
1528                 return 0; // no sharding
1529         }
1530
1531         /**
1532          * Get a list of full container shard suffixes for a container
1533          *
1534          * @param $container string
1535          * @return Array
1536          */
1537         final protected function getContainerSuffixes( $container ) {
1538                 $shards = array();
1539                 $digits = $this->getContainerHashLevels( $container );
1540                 if ( $digits > 0 ) {
1541                         $numShards = 1 << ( $digits * 4 );
1542                         for ( $index = 0; $index < $numShards; $index++ ) {
1543                                 $shards[] = '.' . str_pad( dechex( $index ), $digits, '0', STR_PAD_LEFT );
1544                         }
1545                 }
1546                 return $shards;
1547         }
1548
1549         /**
1550          * Get the full container name, including the wiki ID prefix
1551          *
1552          * @param $container string
1553          * @return string
1554          */
1555         final protected function fullContainerName( $container ) {
1556                 if ( $this->wikiId != '' ) {
1557                         return "{$this->wikiId}-$container";
1558                 } else {
1559                         return $container;
1560                 }
1561         }
1562
1563         /**
1564          * Resolve a container name, checking if it's allowed by the backend.
1565          * This is intended for internal use, such as encoding illegal chars.
1566          * Subclasses can override this to be more restrictive.
1567          *
1568          * @param $container string
1569          * @return string|null
1570          */
1571         protected function resolveContainerName( $container ) {
1572                 return $container;
1573         }
1574
1575         /**
1576          * Resolve a relative storage path, checking if it's allowed by the backend.
1577          * This is intended for internal use, such as encoding illegal chars or perhaps
1578          * getting absolute paths (e.g. FS based backends). Note that the relative path
1579          * may be the empty string (e.g. the path is simply to the container).
1580          *
1581          * @param $container string Container name
1582          * @param $relStoragePath string Storage path relative to the container
1583          * @return string|null Path or null if not valid
1584          */
1585         protected function resolveContainerPath( $container, $relStoragePath ) {
1586                 return $relStoragePath;
1587         }
1588 }
1589
1590 /**
1591  * FileBackendStore helper function to handle file listings that span container shards.
1592  * Do not use this class from places outside of FileBackendStore.
1593  *
1594  * @ingroup FileBackendStore
1595  */
1596 class FileBackendStoreShardListIterator implements Iterator {
1597         /* @var FileBackendStore */
1598         protected $backend;
1599         /* @var Array */
1600         protected $params;
1601         /* @var Array */
1602         protected $shardSuffixes;
1603         protected $container; // string
1604         protected $directory; // string
1605
1606         /* @var Traversable */
1607         protected $iter;
1608         protected $curShard = 0; // integer
1609         protected $pos = 0; // integer
1610
1611         /**
1612          * @param $backend FileBackendStore
1613          * @param $container string Full storage container name
1614          * @param $dir string Storage directory relative to container
1615          * @param $suffixes Array List of container shard suffixes
1616          * @param $params Array
1617          */
1618         public function __construct(
1619                 FileBackendStore $backend, $container, $dir, array $suffixes, array $params
1620         ) {
1621                 $this->backend = $backend;
1622                 $this->container = $container;
1623                 $this->directory = $dir;
1624                 $this->shardSuffixes = $suffixes;
1625                 $this->params = $params;
1626         }
1627
1628         public function current() {
1629                 if ( is_array( $this->iter ) ) {
1630                         return current( $this->iter );
1631                 } else {
1632                         return $this->iter->current();
1633                 }
1634         }
1635
1636         public function key() {
1637                 return $this->pos;
1638         }
1639
1640         public function next() {
1641                 ++$this->pos;
1642                 if ( is_array( $this->iter ) ) {
1643                         next( $this->iter );
1644                 } else {
1645                         $this->iter->next();
1646                 }
1647                 // Find the next non-empty shard if no elements are left
1648                 $this->nextShardIteratorIfNotValid();
1649         }
1650
1651         /**
1652          * If the iterator for this container shard is out of items,
1653          * then move on to the next container that has items.
1654          * If there are none, then it advances to the last container.
1655          */
1656         protected function nextShardIteratorIfNotValid() {
1657                 while ( !$this->valid() ) {
1658                         if ( ++$this->curShard >= count( $this->shardSuffixes ) ) {
1659                                 break; // no more container shards
1660                         }
1661                         $this->setIteratorFromCurrentShard();
1662                 }
1663         }
1664
1665         protected function setIteratorFromCurrentShard() {
1666                 $suffix = $this->shardSuffixes[$this->curShard];
1667                 $this->iter = $this->backend->getFileListInternal(
1668                         "{$this->container}{$suffix}", $this->directory, $this->params );
1669         }
1670
1671         public function rewind() {
1672                 $this->pos = 0;
1673                 $this->curShard = 0;
1674                 $this->setIteratorFromCurrentShard();
1675                 // Find the next non-empty shard if this one has no elements
1676                 $this->nextShardIteratorIfNotValid();
1677         }
1678
1679         public function valid() {
1680                 if ( $this->iter == null ) {
1681                         return false; // some failure?
1682                 } elseif ( is_array( $this->iter ) ) {
1683                         return ( current( $this->iter ) !== false ); // no paths can have this value
1684                 } else {
1685                         return $this->iter->valid();
1686                 }
1687         }
1688 }