includes/filerepo/backend/FileBackend.php

   1 <?php
   2 /**
   3  * @defgroup FileBackend File backend
   4  * @ingroup  FileRepo
   5  *
   6  * File backend is used to interact with file storage systems,
   7  * such as the local file system, NFS, or cloud storage systems.
   8  */
   9
  10 /**
  11  * Base class for all file backends.
  12  *
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 2 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License along
  24  * with this program; if not, write to the Free Software Foundation, Inc.,
  25  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  26  * http://www.gnu.org/copyleft/gpl.html
  27  *
  28  * @file
  29  * @ingroup FileBackend
  30  * @author Aaron Schulz
  31  */
  32
  33 /**
  34  * @brief Base class for all file backend classes (including multi-write backends).
  35  *
  36  * This class defines the methods as abstract that subclasses must implement.
  37  * Outside callers can assume that all backends will have these functions.
  38  *
  39  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
  40  * The <path> portion is a relative path that uses UNIX file system (FS) notation,
  41  * though any particular backend may not actually be using a local filesystem.
  42  * Therefore, the relative paths are only virtual.
  43  *
  44  * Backend contents are stored under wiki-specific container names by default.
  45  * For legacy reasons, this has no effect for the FS backend class, and per-wiki
  46  * segregation must be done by setting the container paths appropriately.
  47  *
  48  * FS-based backends are somewhat more restrictive due to the existence of real
  49  * directory files; a regular file cannot have the same name as a directory. Other
  50  * backends with virtual directories may not have this limitation. Callers should
  51  * store files in such a way that no files and directories are under the same path.
  52  *
  53  * Methods should avoid throwing exceptions at all costs.
  54  * As a corollary, external dependencies should be kept to a minimum.
  55  *
  56  * @ingroup FileBackend
  57  * @since 1.19
  58  */
  59 abstract class FileBackend {
  60         protected $name; // string; unique backend name
  61         protected $wikiId; // string; unique wiki name
  62         protected $readOnly; // string; read-only explanation message
  63         /** @var LockManager */
  64         protected $lockManager;
  65         /** @var FileJournal */
  66         protected $fileJournal;
  67
  68         /**
  69          * Create a new backend instance from configuration.
  70          * This should only be called from within FileBackendGroup.
  71          *
  72          * $config includes:
  73          *     'name'        : The unique name of this backend.
  74          *                     This should consist of alphanumberic, '-', and '_' characters.
  75          *                     This name should not be changed after use.
  76          *     'wikiId'      : Prefix to container names that is unique to this wiki.
  77          *                     It should only consist of alphanumberic, '-', and '_' characters.
  78          *     'lockManager' : Registered name of a file lock manager to use.
  79          *     'fileJournal' : File journal configuration; see FileJournal::factory().
  80          *                     Journals simply log changes to files stored in the backend.
  81          *     'readOnly'    : Write operations are disallowed if this is a non-empty string.
  82          *                     It should be an explanation for the backend being read-only.
  83          *
  84          * @param $config Array
  85          */
  86         public function __construct( array $config ) {
  87                 $this->name = $config['name'];
  88                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
  89                         throw new MWException( "Backend name `{$this->name}` is invalid." );
  90                 }
  91                 $this->wikiId = isset( $config['wikiId'] )
  92                         ? $config['wikiId']
  93                         : wfWikiID(); // e.g. "my_wiki-en_"
  94                 $this->lockManager = ( $config['lockManager'] instanceof LockManager )
  95                         ? $config['lockManager']
  96                         : LockManagerGroup::singleton()->get( $config['lockManager'] );
  97                 $this->fileJournal = isset( $config['fileJournal'] )
  98                         ? FileJournal::factory( $config['fileJournal'], $this->name )
  99                         : FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
 100                 $this->readOnly = isset( $config['readOnly'] )
 101                         ? (string)$config['readOnly']
 102                         : '';
 103         }
 104
 105         /**
 106          * Get the unique backend name.
 107          * We may have multiple different backends of the same type.
 108          * For example, we can have two Swift backends using different proxies.
 109          *
 110          * @return string
 111          */
 112         final public function getName() {
 113                 return $this->name;
 114         }
 115
 116         /**
 117          * Check if this backend is read-only
 118          *
 119          * @return bool
 120          */
 121         final public function isReadOnly() {
 122                 return ( $this->readOnly != '' );
 123         }
 124
 125         /**
 126          * Get an explanatory message if this backend is read-only
 127          *
 128          * @return string|bool Returns false if the backend is not read-only
 129          */
 130         final public function getReadOnlyReason() {
 131                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 132         }
 133
 134         /**
 135          * This is the main entry point into the backend for write operations.
 136          * Callers supply an ordered list of operations to perform as a transaction.
 137          * Files will be locked, the stat cache cleared, and then the operations attempted.
 138          * If any serious errors occur, all attempted operations will be rolled back.
 139          *
 140          * $ops is an array of arrays. The outer array holds a list of operations.
 141          * Each inner array is a set of key value pairs that specify an operation.
 142          *
 143          * Supported operations and their parameters:
 144          * a) Create a new file in storage with the contents of a string
 145          *     array(
 146          *         'op'                  => 'create',
 147          *         'dst'                 => <storage path>,
 148          *         'content'             => <string of new file contents>,
 149          *         'overwrite'           => <boolean>,
 150          *         'overwriteSame'       => <boolean>
 151          *     )
 152          * b) Copy a file system file into storage
 153          *     array(
 154          *         'op'                  => 'store',
 155          *         'src'                 => <file system path>,
 156          *         'dst'                 => <storage path>,
 157          *         'overwrite'           => <boolean>,
 158          *         'overwriteSame'       => <boolean>
 159          *     )
 160          * c) Copy a file within storage
 161          *     array(
 162          *         'op'                  => 'copy',
 163          *         'src'                 => <storage path>,
 164          *         'dst'                 => <storage path>,
 165          *         'overwrite'           => <boolean>,
 166          *         'overwriteSame'       => <boolean>
 167          *     )
 168          * d) Move a file within storage
 169          *     array(
 170          *         'op'                  => 'move',
 171          *         'src'                 => <storage path>,
 172          *         'dst'                 => <storage path>,
 173          *         'overwrite'           => <boolean>,
 174          *         'overwriteSame'       => <boolean>
 175          *     )
 176          * e) Delete a file within storage
 177          *     array(
 178          *         'op'                  => 'delete',
 179          *         'src'                 => <storage path>,
 180          *         'ignoreMissingSource' => <boolean>
 181          *     )
 182          * f) Do nothing (no-op)
 183          *     array(
 184          *         'op'                  => 'null',
 185          *     )
 186          *
 187          * Boolean flags for operations (operation-specific):
 188          * 'ignoreMissingSource' : The operation will simply succeed and do
 189          *                         nothing if the source file does not exist.
 190          * 'overwrite'           : Any destination file will be overwritten.
 191          * 'overwriteSame'       : An error will not be given if a file already
 192          *                         exists at the destination that has the same
 193          *                         contents as the new contents to be written there.
 194          *
 195          * $opts is an associative of boolean flags, including:
 196          * 'force'               : Operation precondition errors no longer trigger an abort.
 197          *                         Any remaining operations are still attempted. Unexpected
 198          *                         failures may still cause remaning operations to be aborted.
 199          * 'nonLocking'          : No locks are acquired for the operations.
 200          *                         This can increase performance for non-critical writes.
 201          *                         This has no effect unless the 'force' flag is set.
 202          * 'allowStale'          : Don't require the latest available data.
 203          *                         This can increase performance for non-critical writes.
 204          *                         This has no effect unless the 'force' flag is set.
 205          * 'nonJournaled'        : Don't log this operation batch in the file journal.
 206          *                         This limits the ability of recovery scripts.
 207          *
 208          * Remarks on locking:
 209          * File system paths given to operations should refer to files that are
 210          * already locked or otherwise safe from modification from other processes.
 211          * Normally these files will be new temp files, which should be adequate.
 212          *
 213          * Return value:
 214          * This returns a Status, which contains all warnings and fatals that occured
 215          * during the operation. The 'failCount', 'successCount', and 'success' members
 216          * will reflect each operation attempted. The status will be "OK" unless:
 217          *     a) unexpected operation errors occurred (network partitions, disk full...)
 218          *     b) significant operation errors occured and 'force' was not set
 219          *
 220          * @param $ops Array List of operations to execute in order
 221          * @param $opts Array Batch operation options
 222          * @return Status
 223          */
 224         final public function doOperations( array $ops, array $opts = array() ) {
 225                 if ( $this->isReadOnly() ) {
 226                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 227                 }
 228                 if ( empty( $opts['force'] ) ) { // sanity
 229                         unset( $opts['nonLocking'] );
 230                         unset( $opts['allowStale'] );
 231                 }
 232                 return $this->doOperationsInternal( $ops, $opts );
 233         }
 234
 235         /**
 236          * @see FileBackend::doOperations()
 237          */
 238         abstract protected function doOperationsInternal( array $ops, array $opts );
 239
 240         /**
 241          * Same as doOperations() except it takes a single operation.
 242          * If you are doing a batch of operations that should either
 243          * all succeed or all fail, then use that function instead.
 244          *
 245          * @see FileBackend::doOperations()
 246          *
 247          * @param $op Array Operation
 248          * @param $opts Array Operation options
 249          * @return Status
 250          */
 251         final public function doOperation( array $op, array $opts = array() ) {
 252                 return $this->doOperations( array( $op ), $opts );
 253         }
 254
 255         /**
 256          * Performs a single create operation.
 257          * This sets $params['op'] to 'create' and passes it to doOperation().
 258          *
 259          * @see FileBackend::doOperation()
 260          *
 261          * @param $params Array Operation parameters
 262          * @param $opts Array Operation options
 263          * @return Status
 264          */
 265         final public function create( array $params, array $opts = array() ) {
 266                 $params['op'] = 'create';
 267                 return $this->doOperation( $params, $opts );
 268         }
 269
 270         /**
 271          * Performs a single store operation.
 272          * This sets $params['op'] to 'store' and passes it to doOperation().
 273          *
 274          * @see FileBackend::doOperation()
 275          *
 276          * @param $params Array Operation parameters
 277          * @param $opts Array Operation options
 278          * @return Status
 279          */
 280         final public function store( array $params, array $opts = array() ) {
 281                 $params['op'] = 'store';
 282                 return $this->doOperation( $params, $opts );
 283         }
 284
 285         /**
 286          * Performs a single copy operation.
 287          * This sets $params['op'] to 'copy' and passes it to doOperation().
 288          *
 289          * @see FileBackend::doOperation()
 290          *
 291          * @param $params Array Operation parameters
 292          * @param $opts Array Operation options
 293          * @return Status
 294          */
 295         final public function copy( array $params, array $opts = array() ) {
 296                 $params['op'] = 'copy';
 297                 return $this->doOperation( $params, $opts );
 298         }
 299
 300         /**
 301          * Performs a single move operation.
 302          * This sets $params['op'] to 'move' and passes it to doOperation().
 303          *
 304          * @see FileBackend::doOperation()
 305          *
 306          * @param $params Array Operation parameters
 307          * @param $opts Array Operation options
 308          * @return Status
 309          */
 310         final public function move( array $params, array $opts = array() ) {
 311                 $params['op'] = 'move';
 312                 return $this->doOperation( $params, $opts );
 313         }
 314
 315         /**
 316          * Performs a single delete operation.
 317          * This sets $params['op'] to 'delete' and passes it to doOperation().
 318          *
 319          * @see FileBackend::doOperation()
 320          *
 321          * @param $params Array Operation parameters
 322          * @param $opts Array Operation options
 323          * @return Status
 324          */
 325         final public function delete( array $params, array $opts = array() ) {
 326                 $params['op'] = 'delete';
 327                 return $this->doOperation( $params, $opts );
 328         }
 329
 330         /**
 331          * Concatenate a list of storage files into a single file system file.
 332          * The target path should refer to a file that is already locked or
 333          * otherwise safe from modification from other processes. Normally,
 334          * the file will be a new temp file, which should be adequate.
 335          * $params include:
 336          *     srcs : ordered source storage paths (e.g. chunk1, chunk2, ...)
 337          *     dst  : file system path to 0-byte temp file
 338          *
 339          * @param $params Array Operation parameters
 340          * @return Status
 341          */
 342         abstract public function concatenate( array $params );
 343
 344         /**
 345          * Prepare a storage directory for usage.
 346          * This will create any required containers and parent directories.
 347          * Backends using key/value stores only need to create the container.
 348          *
 349          * $params include:
 350          *     dir : storage directory
 351          *
 352          * @param $params Array
 353          * @return Status
 354          */
 355         final public function prepare( array $params ) {
 356                 if ( $this->isReadOnly() ) {
 357                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 358                 }
 359                 return $this->doPrepare( $params );
 360         }
 361
 362         /**
 363          * @see FileBackend::prepare()
 364          */
 365         abstract protected function doPrepare( array $params );
 366
 367         /**
 368          * Take measures to block web access to a storage directory and
 369          * the container it belongs to. FS backends might add .htaccess
 370          * files whereas key/value store backends might restrict container
 371          * access to the auth user that represents end-users in web request.
 372          * This is not guaranteed to actually do anything.
 373          *
 374          * $params include:
 375          *     dir       : storage directory
 376          *     noAccess  : try to deny file access
 377          *     noListing : try to deny file listing
 378          *
 379          * @param $params Array
 380          * @return Status
 381          */
 382         final public function secure( array $params ) {
 383                 if ( $this->isReadOnly() ) {
 384                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 385                 }
 386                 $status = $this->doPrepare( $params ); // dir must exist to restrict it
 387                 if ( $status->isOK() ) {
 388                         $status->merge( $this->doSecure( $params ) );
 389                 }
 390                 return $status;
 391         }
 392
 393         /**
 394          * @see FileBackend::secure()
 395          */
 396         abstract protected function doSecure( array $params );
 397
 398         /**
 399          * Delete a storage directory if it is empty.
 400          * Backends using key/value stores may do nothing unless the directory
 401          * is that of an empty container, in which case it should be deleted.
 402          *
 403          * $params include:
 404          *     dir       : storage directory
 405          *     recursive : recursively delete empty subdirectories first (@since 1.20)
 406          *
 407          * @param $params Array
 408          * @return Status
 409          */
 410         final public function clean( array $params ) {
 411                 if ( $this->isReadOnly() ) {
 412                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 413                 }
 414                 return $this->doClean( $params );
 415         }
 416
 417         /**
 418          * @see FileBackend::clean()
 419          */
 420         abstract protected function doClean( array $params );
 421
 422         /**
 423          * Check if a file exists at a storage path in the backend.
 424          * This returns false if only a directory exists at the path.
 425          *
 426          * $params include:
 427          *     src    : source storage path
 428          *     latest : use the latest available data
 429          *
 430          * @param $params Array
 431          * @return bool|null Returns null on failure
 432          */
 433         abstract public function fileExists( array $params );
 434
 435         /**
 436          * Get the last-modified timestamp of the file at a storage path.
 437          *
 438          * $params include:
 439          *     src    : source storage path
 440          *     latest : use the latest available data
 441          *
 442          * @param $params Array
 443          * @return string|bool TS_MW timestamp or false on failure
 444          */
 445         abstract public function getFileTimestamp( array $params );
 446
 447         /**
 448          * Get the contents of a file at a storage path in the backend.
 449          * This should be avoided for potentially large files.
 450          *
 451          * $params include:
 452          *     src    : source storage path
 453          *     latest : use the latest available data
 454          *
 455          * @param $params Array
 456          * @return string|bool Returns false on failure
 457          */
 458         abstract public function getFileContents( array $params );
 459
 460         /**
 461          * Get the size (bytes) of a file at a storage path in the backend.
 462          *
 463          * $params include:
 464          *     src    : source storage path
 465          *     latest : use the latest available data
 466          *
 467          * @param $params Array
 468          * @return integer|bool Returns false on failure
 469          */
 470         abstract public function getFileSize( array $params );
 471
 472         /**
 473          * Get quick information about a file at a storage path in the backend.
 474          * If the file does not exist, then this returns false.
 475          * Otherwise, the result is an associative array that includes:
 476          *     mtime  : the last-modified timestamp (TS_MW)
 477          *     size   : the file size (bytes)
 478          * Additional values may be included for internal use only.
 479          *
 480          * $params include:
 481          *     src    : source storage path
 482          *     latest : use the latest available data
 483          *
 484          * @param $params Array
 485          * @return Array|bool|null Returns null on failure
 486          */
 487         abstract public function getFileStat( array $params );
 488
 489         /**
 490          * Get a SHA-1 hash of the file at a storage path in the backend.
 491          *
 492          * $params include:
 493          *     src    : source storage path
 494          *     latest : use the latest available data
 495          *
 496          * @param $params Array
 497          * @return string|bool Hash string or false on failure
 498          */
 499         abstract public function getFileSha1Base36( array $params );
 500
 501         /**
 502          * Get the properties of the file at a storage path in the backend.
 503          * Returns FSFile::placeholderProps() on failure.
 504          *
 505          * $params include:
 506          *     src    : source storage path
 507          *     latest : use the latest available data
 508          *
 509          * @param $params Array
 510          * @return Array
 511          */
 512         abstract public function getFileProps( array $params );
 513
 514         /**
 515          * Stream the file at a storage path in the backend.
 516          * If the file does not exists, a 404 error will be given.
 517          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
 518          * must be sent if streaming began, while none should be sent otherwise.
 519          * Implementations should flush the output buffer before sending data.
 520          *
 521          * $params include:
 522          *     src     : source storage path
 523          *     headers : additional HTTP headers to send on success
 524          *     latest  : use the latest available data
 525          *
 526          * @param $params Array
 527          * @return Status
 528          */
 529         abstract public function streamFile( array $params );
 530
 531         /**
 532          * Returns a file system file, identical to the file at a storage path.
 533          * The file returned is either:
 534          * a) A local copy of the file at a storage path in the backend.
 535          *    The temporary copy will have the same extension as the source.
 536          * b) An original of the file at a storage path in the backend.
 537          * Temporary files may be purged when the file object falls out of scope.
 538          *
 539          * Write operations should *never* be done on this file as some backends
 540          * may do internal tracking or may be instances of FileBackendMultiWrite.
 541          * In that later case, there are copies of the file that must stay in sync.
 542          * Additionally, further calls to this function may return the same file.
 543          *
 544          * $params include:
 545          *     src    : source storage path
 546          *     latest : use the latest available data
 547          *
 548          * @param $params Array
 549          * @return FSFile|null Returns null on failure
 550          */
 551         abstract public function getLocalReference( array $params );
 552
 553         /**
 554          * Get a local copy on disk of the file at a storage path in the backend.
 555          * The temporary copy will have the same file extension as the source.
 556          * Temporary files may be purged when the file object falls out of scope.
 557          *
 558          * $params include:
 559          *     src    : source storage path
 560          *     latest : use the latest available data
 561          *
 562          * @param $params Array
 563          * @return TempFSFile|null Returns null on failure
 564          */
 565         abstract public function getLocalCopy( array $params );
 566
 567         /**
 568          * Check if a directory exists at a given storage path.
 569          * Backends using key/value stores will check if the path is a
 570          * virtual directory, meaning there are files under the given directory.
 571          *
 572          * Storage backends with eventual consistency might return stale data.
 573          *
 574          * $params include:
 575          *     dir : storage directory
 576          *
 577          * @return bool|null Returns null on failure
 578          * @since 1.20
 579          */
 580         abstract public function directoryExists( array $params );
 581
 582         /**
 583          * Get an iterator to list *all* directories under a storage directory.
 584          * If the directory is of the form "mwstore://backend/container",
 585          * then all directories in the container should be listed.
 586          * If the directory is of form "mwstore://backend/container/dir",
 587          * then all directories directly under that directory should be listed.
 588          * Results should be storage directories relative to the given directory.
 589          *
 590          * Storage backends with eventual consistency might return stale data.
 591          *
 592          * $params include:
 593          *     dir     : storage directory
 594          *     topOnly : only return direct child dirs of the directory
 595          *
 596          * @return Traversable|Array|null Returns null on failure
 597          * @since 1.20
 598          */
 599         abstract public function getDirectoryList( array $params );
 600
 601         /**
 602          * Same as FileBackend::getDirectoryList() except only lists
 603          * directories that are immediately under the given directory.
 604          *
 605          * Storage backends with eventual consistency might return stale data.
 606          *
 607          * $params include:
 608          *     dir : storage directory
 609          *
 610          * @return Traversable|Array|null Returns null on failure
 611          * @since 1.20
 612          */
 613         final public function getTopDirectoryList( array $params ) {
 614                 return $this->getDirectoryList( array( 'topOnly' => true ) + $params );
 615         }
 616
 617         /**
 618          * Get an iterator to list *all* stored files under a storage directory.
 619          * If the directory is of the form "mwstore://backend/container",
 620          * then all files in the container should be listed.
 621          * If the directory is of form "mwstore://backend/container/dir",
 622          * then all files under that directory should be listed.
 623          * Results should be storage paths relative to the given directory.
 624          *
 625          * Storage backends with eventual consistency might return stale data.
 626          *
 627          * $params include:
 628          *     dir     : storage directory
 629          *     topOnly : only return direct child files of the directory (@since 1.20)
 630          *
 631          * @return Traversable|Array|null Returns null on failure
 632          */
 633         abstract public function getFileList( array $params );
 634
 635         /**
 636          * Same as FileBackend::getFileList() except only lists
 637          * files that are immediately under the given directory.
 638          *
 639          * Storage backends with eventual consistency might return stale data.
 640          *
 641          * $params include:
 642          *     dir : storage directory
 643          *
 644          * @return Traversable|Array|null Returns null on failure
 645          * @since 1.20
 646          */
 647         final public function getTopFileList( array $params ) {
 648                 return $this->getFileList( array( 'topOnly' => true ) + $params );
 649         }
 650
 651         /**
 652          * Invalidate any in-process file existence and property cache.
 653          * If $paths is given, then only the cache for those files will be cleared.
 654          *
 655          * @param $paths Array Storage paths (optional)
 656          * @return void
 657          */
 658         public function clearCache( array $paths = null ) {}
 659
 660         /**
 661          * Lock the files at the given storage paths in the backend.
 662          * This will either lock all the files or none (on failure).
 663          *
 664          * Callers should consider using getScopedFileLocks() instead.
 665          *
 666          * @param $paths Array Storage paths
 667          * @param $type integer LockManager::LOCK_* constant
 668          * @return Status
 669          */
 670         final public function lockFiles( array $paths, $type ) {
 671                 return $this->lockManager->lock( $paths, $type );
 672         }
 673
 674         /**
 675          * Unlock the files at the given storage paths in the backend.
 676          *
 677          * @param $paths Array Storage paths
 678          * @param $type integer LockManager::LOCK_* constant
 679          * @return Status
 680          */
 681         final public function unlockFiles( array $paths, $type ) {
 682                 return $this->lockManager->unlock( $paths, $type );
 683         }
 684
 685         /**
 686          * Lock the files at the given storage paths in the backend.
 687          * This will either lock all the files or none (on failure).
 688          * On failure, the status object will be updated with errors.
 689          *
 690          * Once the return value goes out scope, the locks will be released and
 691          * the status updated. Unlock fatals will not change the status "OK" value.
 692          *
 693          * @param $paths Array Storage paths
 694          * @param $type integer LockManager::LOCK_* constant
 695          * @param $status Status Status to update on lock/unlock
 696          * @return ScopedLock|null Returns null on failure
 697          */
 698         final public function getScopedFileLocks( array $paths, $type, Status $status ) {
 699                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status );
 700         }
 701
 702         /**
 703          * Get the root storage path of this backend.
 704          * All container paths are "subdirectories" of this path.
 705          *
 706          * @return string Storage path
 707          * @since 1.20
 708          */
 709         final public function getRootStoragePath() {
 710                 return "mwstore://{$this->name}";
 711         }
 712
 713         /**
 714          * Check if a given path is a "mwstore://" path.
 715          * This does not do any further validation or any existence checks.
 716          *
 717          * @param $path string
 718          * @return bool
 719          */
 720         final public static function isStoragePath( $path ) {
 721                 return ( strpos( $path, 'mwstore://' ) === 0 );
 722         }
 723
 724         /**
 725          * Split a storage path into a backend name, a container name,
 726          * and a relative file path. The relative path may be the empty string.
 727          * This does not do any path normalization or traversal checks.
 728          *
 729          * @param $storagePath string
 730          * @return Array (backend, container, rel object) or (null, null, null)
 731          */
 732         final public static function splitStoragePath( $storagePath ) {
 733                 if ( self::isStoragePath( $storagePath ) ) {
 734                         // Remove the "mwstore://" prefix and split the path
 735                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
 736                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
 737                                 if ( count( $parts ) == 3 ) {
 738                                         return $parts; // e.g. "backend/container/path"
 739                                 } else {
 740                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
 741                                 }
 742                         }
 743                 }
 744                 return array( null, null, null );
 745         }
 746
 747         /**
 748          * Normalize a storage path by cleaning up directory separators.
 749          * Returns null if the path is not of the format of a valid storage path.
 750          *
 751          * @param $storagePath string
 752          * @return string|null
 753          */
 754         final public static function normalizeStoragePath( $storagePath ) {
 755                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
 756                 if ( $relPath !== null ) { // must be for this backend
 757                         $relPath = self::normalizeContainerPath( $relPath );
 758                         if ( $relPath !== null ) {
 759                                 return ( $relPath != '' )
 760                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
 761                                         : "mwstore://{$backend}/{$container}";
 762                         }
 763                 }
 764                 return null;
 765         }
 766
 767         /**
 768          * Get the parent storage directory of a storage path.
 769          * This returns a path like "mwstore://backend/container",
 770          * "mwstore://backend/container/...", or null if there is no parent.
 771          *
 772          * @param $storagePath string
 773          * @return string|null
 774          */
 775         final public static function parentStoragePath( $storagePath ) {
 776                 $storagePath = dirname( $storagePath );
 777                 list( $b, $cont, $rel ) = self::splitStoragePath( $storagePath );
 778                 return ( $rel === null ) ? null : $storagePath;
 779         }
 780
 781         /**
 782          * Get the final extension from a storage or FS path
 783          *
 784          * @param $path string
 785          * @return string
 786          */
 787         final public static function extensionFromPath( $path ) {
 788                 $i = strrpos( $path, '.' );
 789                 return strtolower( $i ? substr( $path, $i + 1 ) : '' );
 790         }
 791
 792         /**
 793          * Check if a relative path has no directory traversals
 794          *
 795          * @param $path string
 796          * @return bool
 797          * @since 1.20
 798          */
 799         final public static function isPathTraversalFree( $path ) {
 800                 return ( self::normalizeContainerPath( $path ) !== null );
 801         }
 802
 803         /**
 804          * Validate and normalize a relative storage path.
 805          * Null is returned if the path involves directory traversal.
 806          * Traversal is insecure for FS backends and broken for others.
 807          *
 808          * This uses the same traversal protection as Title::secureAndSplit().
 809          *
 810          * @param $path string Storage path relative to a container
 811          * @return string|null
 812          */
 813         final protected static function normalizeContainerPath( $path ) {
 814                 // Normalize directory separators
 815                 $path = strtr( $path, '\\', '/' );
 816                 // Collapse any consecutive directory separators
 817                 $path = preg_replace( '![/]{2,}!', '/', $path );
 818                 // Remove any leading directory separator
 819                 $path = ltrim( $path, '/' );
 820                 // Use the same traversal protection as Title::secureAndSplit()
 821                 if ( strpos( $path, '.' ) !== false ) {
 822                         if (
 823                                 $path === '.' ||
 824                                 $path === '..' ||
 825                                 strpos( $path, './' ) === 0 ||
 826                                 strpos( $path, '../' ) === 0 ||
 827                                 strpos( $path, '/./' ) !== false ||
 828                                 strpos( $path, '/../' ) !== false
 829                         ) {
 830                                 return null;
 831                         }
 832                 }
 833                 return $path;
 834         }
 835 }