includes/filebackend/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)
  41  * notation, though any particular backend may not actually be using a local
  42  * filesystem. 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 of subclasses 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         protected $parallelize; // string; when to do operations in parallel
  64         protected $concurrency; // integer; how many operations can be done in parallel
  65
  66         /** @var LockManager */
  67         protected $lockManager;
  68         /** @var FileJournal */
  69         protected $fileJournal;
  70
  71         /**
  72          * Create a new backend instance from configuration.
  73          * This should only be called from within FileBackendGroup.
  74          *
  75          * $config includes:
  76          *   - name        : The unique name of this backend.
  77          *                   This should consist of alphanumberic, '-', and '_' characters.
  78          *                   This name should not be changed after use.
  79          *   - wikiId      : Prefix to container names that is unique to this wiki.
  80          *                   If not provided, this defaults to the current wiki ID.
  81          *                   It should only consist of alphanumberic, '-', and '_' characters.
  82          *   - lockManager : Registered name of a file lock manager to use.
  83          *   - fileJournal : File journal configuration; see FileJournal::factory().
  84          *                   Journals simply log changes to files stored in the backend.
  85          *   - readOnly    : Write operations are disallowed if this is a non-empty string.
  86          *                   It should be an explanation for the backend being read-only.
  87          *   - parallelize : When to do file operations in parallel (when possible).
  88          *                   Allowed values are "implicit", "explicit" and "off".
  89          *   - concurrency : How many file operations can be done in parallel.
  90          *
  91          * @param $config Array
  92          * @throws MWException
  93          */
  94         public function __construct( array $config ) {
  95                 $this->name = $config['name'];
  96                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
  97                         throw new MWException( "Backend name `{$this->name}` is invalid." );
  98                 }
  99                 $this->wikiId = isset( $config['wikiId'] )
 100                         ? $config['wikiId']
 101                         : wfWikiID(); // e.g. "my_wiki-en_"
 102                 $this->lockManager = ( $config['lockManager'] instanceof LockManager )
 103                         ? $config['lockManager']
 104                         : LockManagerGroup::singleton( $this->wikiId )->get( $config['lockManager'] );
 105                 $this->fileJournal = isset( $config['fileJournal'] )
 106                         ? ( ( $config['fileJournal'] instanceof FileJournal )
 107                                 ? $config['fileJournal']
 108                                 : FileJournal::factory( $config['fileJournal'], $this->name ) )
 109                         : FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
 110                 $this->readOnly = isset( $config['readOnly'] )
 111                         ? (string)$config['readOnly']
 112                         : '';
 113                 $this->parallelize = isset( $config['parallelize'] )
 114                         ? (string)$config['parallelize']
 115                         : 'off';
 116                 $this->concurrency = isset( $config['concurrency'] )
 117                         ? (int)$config['concurrency']
 118                         : 50;
 119         }
 120
 121         /**
 122          * Get the unique backend name.
 123          * We may have multiple different backends of the same type.
 124          * For example, we can have two Swift backends using different proxies.
 125          *
 126          * @return string
 127          */
 128         final public function getName() {
 129                 return $this->name;
 130         }
 131
 132         /**
 133          * Get the wiki identifier used for this backend (possibly empty).
 134          * Note that this might *not* be in the same format as wfWikiID().
 135          *
 136          * @return string
 137          * @since 1.20
 138          */
 139         final public function getWikiId() {
 140                 return $this->wikiId;
 141         }
 142
 143         /**
 144          * Check if this backend is read-only
 145          *
 146          * @return bool
 147          */
 148         final public function isReadOnly() {
 149                 return ( $this->readOnly != '' );
 150         }
 151
 152         /**
 153          * Get an explanatory message if this backend is read-only
 154          *
 155          * @return string|bool Returns false if the backend is not read-only
 156          */
 157         final public function getReadOnlyReason() {
 158                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 159         }
 160
 161         /**
 162          * This is the main entry point into the backend for write operations.
 163          * Callers supply an ordered list of operations to perform as a transaction.
 164          * Files will be locked, the stat cache cleared, and then the operations attempted.
 165          * If any serious errors occur, all attempted operations will be rolled back.
 166          *
 167          * $ops is an array of arrays. The outer array holds a list of operations.
 168          * Each inner array is a set of key value pairs that specify an operation.
 169          *
 170          * Supported operations and their parameters. The supported actions are:
 171          *  - create
 172          *  - store
 173          *  - copy
 174          *  - move
 175          *  - delete
 176          *  - describe (since 1.21)
 177          *  - null
 178          *
 179          * a) Create a new file in storage with the contents of a string
 180          * @code
 181          *     array(
 182          *         'op'                  => 'create',
 183          *         'dst'                 => <storage path>,
 184          *         'content'             => <string of new file contents>,
 185          *         'overwrite'           => <boolean>,
 186          *         'overwriteSame'       => <boolean>,
 187          *         'disposition'         => <Content-Disposition header value>,
 188          *         'headers'             => <HTTP header name/value map> # since 1.21
 189          *     );
 190          * @endcode
 191          *
 192          * b) Copy a file system file into storage
 193          * @code
 194          *     array(
 195          *         'op'                  => 'store',
 196          *         'src'                 => <file system path>,
 197          *         'dst'                 => <storage path>,
 198          *         'overwrite'           => <boolean>,
 199          *         'overwriteSame'       => <boolean>,
 200          *         'disposition'         => <Content-Disposition header value>,
 201          *         'headers'             => <HTTP header name/value map> # since 1.21
 202          *     )
 203          * @endcode
 204          *
 205          * c) Copy a file within storage
 206          * @code
 207          *     array(
 208          *         'op'                  => 'copy',
 209          *         'src'                 => <storage path>,
 210          *         'dst'                 => <storage path>,
 211          *         'overwrite'           => <boolean>,
 212          *         'overwriteSame'       => <boolean>,
 213          *         'ignoreMissingSource' => <boolean>, # since 1.21
 214          *         'disposition'         => <Content-Disposition header value>
 215          *     )
 216          * @endcode
 217          *
 218          * d) Move a file within storage
 219          * @code
 220          *     array(
 221          *         'op'                  => 'move',
 222          *         'src'                 => <storage path>,
 223          *         'dst'                 => <storage path>,
 224          *         'overwrite'           => <boolean>,
 225          *         'overwriteSame'       => <boolean>,
 226          *         'ignoreMissingSource' => <boolean>, # since 1.21
 227          *         'disposition'         => <Content-Disposition header value>
 228          *     )
 229          * @endcode
 230          *
 231          * e) Delete a file within storage
 232          * @code
 233          *     array(
 234          *         'op'                  => 'delete',
 235          *         'src'                 => <storage path>,
 236          *         'ignoreMissingSource' => <boolean>
 237          *     )
 238          * @endcode
 239          *
 240          * f) Update metadata for a file within storage
 241          * @code
 242          *     array(
 243          *         'op'                  => 'describe',
 244          *         'src'                 => <storage path>,
 245          *         'disposition'         => <Content-Disposition header value>,
 246          *         'headers'             => <HTTP header name/value map>
 247          *     )
 248          * @endcode
 249          *
 250          * g) Do nothing (no-op)
 251          * @code
 252          *     array(
 253          *         'op'                  => 'null',
 254          *     )
 255          * @endcode
 256          *
 257          * Boolean flags for operations (operation-specific):
 258          *   - ignoreMissingSource : The operation will simply succeed and do
 259          *                           nothing if the source file does not exist.
 260          *   - overwrite           : Any destination file will be overwritten.
 261          *   - overwriteSame       : An error will not be given if a file already
 262          *                           exists at the destination that has the same
 263          *                           contents as the new contents to be written there.
 264          *   - disposition         : If supplied, the backend will return a Content-Disposition
 265          *                           header when GETs/HEADs of the destination file are made.
 266          *                           Backends that don't support metadata ignore this.
 267          *                           See http://tools.ietf.org/html/rfc6266. (since 1.20)
 268          *   - headers             : If supplied, the backend will return these headers when
 269          *                           GETs/HEADs of the destination file are made. Header values
 270          *                           should be smaller than 256 bytes, often options or numbers.
 271          *                           Existing headers will remain, but these will replace any
 272          *                           conflicting previous headers, and headers will be removed
 273          *                           if they are set to an empty string.
 274          *                           Backends that don't support metadata ignore this. (since 1.21)
 275          *
 276          * $opts is an associative of boolean flags, including:
 277          *   - force               : Operation precondition errors no longer trigger an abort.
 278          *                           Any remaining operations are still attempted. Unexpected
 279          *                           failures may still cause remaning operations to be aborted.
 280          *   - nonLocking          : No locks are acquired for the operations.
 281          *                           This can increase performance for non-critical writes.
 282          *                           This has no effect unless the 'force' flag is set.
 283          *   - nonJournaled        : Don't log this operation batch in the file journal.
 284          *                           This limits the ability of recovery scripts.
 285          *   - parallelize         : Try to do operations in parallel when possible.
 286          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 287          *   - preserveCache       : Don't clear the process cache before checking files.
 288          *                           This should only be used if all entries in the process
 289          *                           cache were added after the files were already locked. (since 1.20)
 290          *
 291          * @remarks Remarks on locking:
 292          * File system paths given to operations should refer to files that are
 293          * already locked or otherwise safe from modification from other processes.
 294          * Normally these files will be new temp files, which should be adequate.
 295          *
 296          * @par Return value:
 297          *
 298          * This returns a Status, which contains all warnings and fatals that occurred
 299          * during the operation. The 'failCount', 'successCount', and 'success' members
 300          * will reflect each operation attempted.
 301          *
 302          * The status will be "OK" unless:
 303          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 304          *   - b) significant operation errors occurred and 'force' was not set
 305          *
 306          * @param $ops Array List of operations to execute in order
 307          * @param $opts Array Batch operation options
 308          * @return Status
 309          */
 310         final public function doOperations( array $ops, array $opts = array() ) {
 311                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 312                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 313                 }
 314                 if ( empty( $opts['force'] ) ) { // sanity
 315                         unset( $opts['nonLocking'] );
 316                 }
 317                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 318                 return $this->doOperationsInternal( $ops, $opts );
 319         }
 320
 321         /**
 322          * @see FileBackend::doOperations()
 323          */
 324         abstract protected function doOperationsInternal( array $ops, array $opts );
 325
 326         /**
 327          * Same as doOperations() except it takes a single operation.
 328          * If you are doing a batch of operations that should either
 329          * all succeed or all fail, then use that function instead.
 330          *
 331          * @see FileBackend::doOperations()
 332          *
 333          * @param $op Array Operation
 334          * @param $opts Array Operation options
 335          * @return Status
 336          */
 337         final public function doOperation( array $op, array $opts = array() ) {
 338                 return $this->doOperations( array( $op ), $opts );
 339         }
 340
 341         /**
 342          * Performs a single create operation.
 343          * This sets $params['op'] to 'create' and passes it to doOperation().
 344          *
 345          * @see FileBackend::doOperation()
 346          *
 347          * @param $params Array Operation parameters
 348          * @param $opts Array Operation options
 349          * @return Status
 350          */
 351         final public function create( array $params, array $opts = array() ) {
 352                 return $this->doOperation( array( 'op' => 'create' ) + $params, $opts );
 353         }
 354
 355         /**
 356          * Performs a single store operation.
 357          * This sets $params['op'] to 'store' and passes it to doOperation().
 358          *
 359          * @see FileBackend::doOperation()
 360          *
 361          * @param $params Array Operation parameters
 362          * @param $opts Array Operation options
 363          * @return Status
 364          */
 365         final public function store( array $params, array $opts = array() ) {
 366                 return $this->doOperation( array( 'op' => 'store' ) + $params, $opts );
 367         }
 368
 369         /**
 370          * Performs a single copy operation.
 371          * This sets $params['op'] to 'copy' and passes it to doOperation().
 372          *
 373          * @see FileBackend::doOperation()
 374          *
 375          * @param $params Array Operation parameters
 376          * @param $opts Array Operation options
 377          * @return Status
 378          */
 379         final public function copy( array $params, array $opts = array() ) {
 380                 return $this->doOperation( array( 'op' => 'copy' ) + $params, $opts );
 381         }
 382
 383         /**
 384          * Performs a single move operation.
 385          * This sets $params['op'] to 'move' and passes it to doOperation().
 386          *
 387          * @see FileBackend::doOperation()
 388          *
 389          * @param $params Array Operation parameters
 390          * @param $opts Array Operation options
 391          * @return Status
 392          */
 393         final public function move( array $params, array $opts = array() ) {
 394                 return $this->doOperation( array( 'op' => 'move' ) + $params, $opts );
 395         }
 396
 397         /**
 398          * Performs a single delete operation.
 399          * This sets $params['op'] to 'delete' and passes it to doOperation().
 400          *
 401          * @see FileBackend::doOperation()
 402          *
 403          * @param $params Array Operation parameters
 404          * @param $opts Array Operation options
 405          * @return Status
 406          */
 407         final public function delete( array $params, array $opts = array() ) {
 408                 return $this->doOperation( array( 'op' => 'delete' ) + $params, $opts );
 409         }
 410
 411         /**
 412          * Performs a single describe operation.
 413          * This sets $params['op'] to 'describe' and passes it to doOperation().
 414          *
 415          * @see FileBackend::doOperation()
 416          *
 417          * @param $params Array Operation parameters
 418          * @param $opts Array Operation options
 419          * @return Status
 420          * @since 1.21
 421          */
 422         final public function describe( array $params, array $opts = array() ) {
 423                 return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
 424         }
 425
 426         /**
 427          * Perform a set of independent file operations on some files.
 428          *
 429          * This does no locking, nor journaling, and possibly no stat calls.
 430          * Any destination files that already exist will be overwritten.
 431          * This should *only* be used on non-original files, like cache files.
 432          *
 433          * Supported operations and their parameters:
 434          *  - create
 435          *  - store
 436          *  - copy
 437          *  - move
 438          *  - delete
 439          *  - describe (since 1.21)
 440          *  - null
 441          *
 442          * a) Create a new file in storage with the contents of a string
 443          * @code
 444          *     array(
 445          *         'op'                  => 'create',
 446          *         'dst'                 => <storage path>,
 447          *         'content'             => <string of new file contents>,
 448          *         'disposition'         => <Content-Disposition header value>,
 449          *         'headers'             => <HTTP header name/value map> # since 1.21
 450          *     )
 451          * @endcode
 452          *
 453          * b) Copy a file system file into storage
 454          * @code
 455          *     array(
 456          *         'op'                  => 'store',
 457          *         'src'                 => <file system path>,
 458          *         'dst'                 => <storage path>,
 459          *         'disposition'         => <Content-Disposition header value>,
 460          *         'headers'             => <HTTP header name/value map> # since 1.21
 461          *     )
 462          * @endcode
 463          *
 464          * c) Copy a file within storage
 465          * @code
 466          *     array(
 467          *         'op'                  => 'copy',
 468          *         'src'                 => <storage path>,
 469          *         'dst'                 => <storage path>,
 470          *         'ignoreMissingSource' => <boolean>, # since 1.21
 471          *         'disposition'         => <Content-Disposition header value>
 472          *     )
 473          * @endcode
 474          *
 475          * d) Move a file within storage
 476          * @code
 477          *     array(
 478          *         'op'                  => 'move',
 479          *         'src'                 => <storage path>,
 480          *         'dst'                 => <storage path>,
 481          *         'ignoreMissingSource' => <boolean>, # since 1.21
 482          *         'disposition'         => <Content-Disposition header value>
 483          *     )
 484          * @endcode
 485          *
 486          * e) Delete a file within storage
 487          * @code
 488          *     array(
 489          *         'op'                  => 'delete',
 490          *         'src'                 => <storage path>,
 491          *         'ignoreMissingSource' => <boolean>
 492          *     )
 493          * @endcode
 494          *
 495          * f) Update metadata for a file within storage
 496          * @code
 497          *     array(
 498          *         'op'                  => 'describe',
 499          *         'src'                 => <storage path>,
 500          *         'disposition'         => <Content-Disposition header value>,
 501          *         'headers'             => <HTTP header name/value map>
 502          *     )
 503          * @endcode
 504          *
 505          * g) Do nothing (no-op)
 506          * @code
 507          *     array(
 508          *         'op'                  => 'null',
 509          *     )
 510          * @endcode
 511          *
 512          * @par Boolean flags for operations (operation-specific):
 513          *   - ignoreMissingSource : The operation will simply succeed and do
 514          *                           nothing if the source file does not exist.
 515          *   - disposition         : When supplied, the backend will add a Content-Disposition
 516          *                           header when GETs/HEADs of the destination file are made.
 517          *                           Backends that don't support file metadata will ignore this.
 518          *                           See http://tools.ietf.org/html/rfc6266 (since 1.20).
 519          *   - headers             : If supplied with a header name/value map, the backend will
 520          *                           reply with these headers when GETs/HEADs of the destination
 521          *                           file are made. Header values should be smaller than 256 bytes.
 522          *                           Existing headers will remain, but these will replace any
 523          *                           conflicting previous headers, and headers will be removed
 524          *                           if they are set to an empty string.
 525          *                           Backends that don't support metadata ignore this. (since 1.21)
 526          *
 527          * $opts is an associative of boolean flags, including:
 528          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 529          *
 530          * @par Return value:
 531          * This returns a Status, which contains all warnings and fatals that occurred
 532          * during the operation. The 'failCount', 'successCount', and 'success' members
 533          * will reflect each operation attempted for the given files. The status will be
 534          * considered "OK" as long as no fatal errors occurred.
 535          *
 536          * @param $ops Array Set of operations to execute
 537          * @param $opts Array Batch operation options
 538          * @return Status
 539          * @since 1.20
 540          */
 541         final public function doQuickOperations( array $ops, array $opts = array() ) {
 542                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 543                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 544                 }
 545                 foreach ( $ops as &$op ) {
 546                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 547                 }
 548                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 549                 return $this->doQuickOperationsInternal( $ops );
 550         }
 551
 552         /**
 553          * @see FileBackend::doQuickOperations()
 554          * @since 1.20
 555          */
 556         abstract protected function doQuickOperationsInternal( array $ops );
 557
 558         /**
 559          * Same as doQuickOperations() except it takes a single operation.
 560          * If you are doing a batch of operations, then use that function instead.
 561          *
 562          * @see FileBackend::doQuickOperations()
 563          *
 564          * @param $op Array Operation
 565          * @return Status
 566          * @since 1.20
 567          */
 568         final public function doQuickOperation( array $op ) {
 569                 return $this->doQuickOperations( array( $op ) );
 570         }
 571
 572         /**
 573          * Performs a single quick create operation.
 574          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 575          *
 576          * @see FileBackend::doQuickOperation()
 577          *
 578          * @param $params Array Operation parameters
 579          * @return Status
 580          * @since 1.20
 581          */
 582         final public function quickCreate( array $params ) {
 583                 return $this->doQuickOperation( array( 'op' => 'create' ) + $params );
 584         }
 585
 586         /**
 587          * Performs a single quick store operation.
 588          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 589          *
 590          * @see FileBackend::doQuickOperation()
 591          *
 592          * @param $params Array Operation parameters
 593          * @return Status
 594          * @since 1.20
 595          */
 596         final public function quickStore( array $params ) {
 597                 return $this->doQuickOperation( array( 'op' => 'store' ) + $params );
 598         }
 599
 600         /**
 601          * Performs a single quick copy operation.
 602          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 603          *
 604          * @see FileBackend::doQuickOperation()
 605          *
 606          * @param $params Array Operation parameters
 607          * @return Status
 608          * @since 1.20
 609          */
 610         final public function quickCopy( array $params ) {
 611                 return $this->doQuickOperation( array( 'op' => 'copy' ) + $params );
 612         }
 613
 614         /**
 615          * Performs a single quick move operation.
 616          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 617          *
 618          * @see FileBackend::doQuickOperation()
 619          *
 620          * @param $params Array Operation parameters
 621          * @return Status
 622          * @since 1.20
 623          */
 624         final public function quickMove( array $params ) {
 625                 return $this->doQuickOperation( array( 'op' => 'move' ) + $params );
 626         }
 627
 628         /**
 629          * Performs a single quick delete operation.
 630          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 631          *
 632          * @see FileBackend::doQuickOperation()
 633          *
 634          * @param $params Array Operation parameters
 635          * @return Status
 636          * @since 1.20
 637          */
 638         final public function quickDelete( array $params ) {
 639                 return $this->doQuickOperation( array( 'op' => 'delete' ) + $params );
 640         }
 641
 642         /**
 643          * Performs a single quick describe operation.
 644          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 645          *
 646          * @see FileBackend::doQuickOperation()
 647          *
 648          * @param $params Array Operation parameters
 649          * @return Status
 650          * @since 1.21
 651          */
 652         final public function quickDescribe( array $params ) {
 653                 return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
 654         }
 655
 656         /**
 657          * Concatenate a list of storage files into a single file system file.
 658          * The target path should refer to a file that is already locked or
 659          * otherwise safe from modification from other processes. Normally,
 660          * the file will be a new temp file, which should be adequate.
 661          *
 662          * @param $params Array Operation parameters
 663          * $params include:
 664          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 665          *   - dst         : file system path to 0-byte temp file
 666          *   - parallelize : try to do operations in parallel when possible
 667          * @return Status
 668          */
 669         abstract public function concatenate( array $params );
 670
 671         /**
 672          * Prepare a storage directory for usage.
 673          * This will create any required containers and parent directories.
 674          * Backends using key/value stores only need to create the container.
 675          *
 676          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 677          * except they are only applied *if* the directory/container had to be created.
 678          * These flags should always be set for directories that have private files.
 679          *
 680          * @param $params Array
 681          * $params include:
 682          *   - dir            : storage directory
 683          *   - noAccess       : try to deny file access (since 1.20)
 684          *   - noListing      : try to deny file listing (since 1.20)
 685          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 686          * @return Status
 687          */
 688         final public function prepare( array $params ) {
 689                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 690                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 691                 }
 692                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 693                 return $this->doPrepare( $params );
 694         }
 695
 696         /**
 697          * @see FileBackend::prepare()
 698          */
 699         abstract protected function doPrepare( array $params );
 700
 701         /**
 702          * Take measures to block web access to a storage directory and
 703          * the container it belongs to. FS backends might add .htaccess
 704          * files whereas key/value store backends might revoke container
 705          * access to the storage user representing end-users in web requests.
 706          * This is not guaranteed to actually do anything.
 707          *
 708          * @param $params Array
 709          * $params include:
 710          *   - dir            : storage directory
 711          *   - noAccess       : try to deny file access
 712          *   - noListing      : try to deny file listing
 713          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 714          * @return Status
 715          */
 716         final public function secure( array $params ) {
 717                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 718                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 719                 }
 720                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 721                 return $this->doSecure( $params );
 722         }
 723
 724         /**
 725          * @see FileBackend::secure()
 726          */
 727         abstract protected function doSecure( array $params );
 728
 729         /**
 730          * Remove measures to block web access to a storage directory and
 731          * the container it belongs to. FS backends might remove .htaccess
 732          * files whereas key/value store backends might grant container
 733          * access to the storage user representing end-users in web requests.
 734          * This essentially can undo the result of secure() calls.
 735          *
 736          * @param $params Array
 737          * $params include:
 738          *   - dir            : storage directory
 739          *   - access         : try to allow file access
 740          *   - listing        : try to allow file listing
 741          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 742          * @return Status
 743          * @since 1.20
 744          */
 745         final public function publish( array $params ) {
 746                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 747                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 748                 }
 749                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 750                 return $this->doPublish( $params );
 751         }
 752
 753         /**
 754          * @see FileBackend::publish()
 755          */
 756         abstract protected function doPublish( array $params );
 757
 758         /**
 759          * Delete a storage directory if it is empty.
 760          * Backends using key/value stores may do nothing unless the directory
 761          * is that of an empty container, in which case it will be deleted.
 762          *
 763          * @param $params Array
 764          * $params include:
 765          *   - dir            : storage directory
 766          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 767          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 768          * @return Status
 769          */
 770         final public function clean( array $params ) {
 771                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 772                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 773                 }
 774                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 775                 return $this->doClean( $params );
 776         }
 777
 778         /**
 779          * @see FileBackend::clean()
 780          */
 781         abstract protected function doClean( array $params );
 782
 783         /**
 784          * Enter file operation scope.
 785          * This just makes PHP ignore user aborts/disconnects until the return
 786          * value leaves scope. This returns null and does nothing in CLI mode.
 787          *
 788          * @return ScopedCallback|null
 789          */
 790         final protected function getScopedPHPBehaviorForOps() {
 791                 if ( php_sapi_name() != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 792                         $old = ignore_user_abort( true ); // avoid half-finished operations
 793                         return new ScopedCallback( function() use ( $old ) { ignore_user_abort( $old ); } );
 794                 }
 795                 return null;
 796         }
 797
 798         /**
 799          * Check if a file exists at a storage path in the backend.
 800          * This returns false if only a directory exists at the path.
 801          *
 802          * @param $params Array
 803          * $params include:
 804          *   - src    : source storage path
 805          *   - latest : use the latest available data
 806          * @return bool|null Returns null on failure
 807          */
 808         abstract public function fileExists( array $params );
 809
 810         /**
 811          * Get the last-modified timestamp of the file at a storage path.
 812          *
 813          * @param $params Array
 814          * $params include:
 815          *   - src    : source storage path
 816          *   - latest : use the latest available data
 817          * @return string|bool TS_MW timestamp or false on failure
 818          */
 819         abstract public function getFileTimestamp( array $params );
 820
 821         /**
 822          * Get the contents of a file at a storage path in the backend.
 823          * This should be avoided for potentially large files.
 824          *
 825          * @param $params Array
 826          * $params include:
 827          *   - src    : source storage path
 828          *   - latest : use the latest available data
 829          * @return string|bool Returns false on failure
 830          */
 831         final public function getFileContents( array $params ) {
 832                 $contents = $this->getFileContentsMulti(
 833                         array( 'srcs' => array( $params['src'] ) ) + $params );
 834
 835                 return $contents[$params['src']];
 836         }
 837
 838         /**
 839          * Like getFileContents() except it takes an array of storage paths
 840          * and returns a map of storage paths to strings (or null on failure).
 841          * The map keys (paths) are in the same order as the provided list of paths.
 842          *
 843          * @see FileBackend::getFileContents()
 844          *
 845          * @param $params Array
 846          * $params include:
 847          *   - srcs        : list of source storage paths
 848          *   - latest      : use the latest available data
 849          *   - parallelize : try to do operations in parallel when possible
 850          * @return Array Map of (path name => string or false on failure)
 851          * @since 1.20
 852          */
 853         abstract public function getFileContentsMulti( array $params );
 854
 855         /**
 856          * Get the size (bytes) of a file at a storage path in the backend.
 857          *
 858          * @param $params Array
 859          * $params include:
 860          *   - src    : source storage path
 861          *   - latest : use the latest available data
 862          * @return integer|bool Returns false on failure
 863          */
 864         abstract public function getFileSize( array $params );
 865
 866         /**
 867          * Get quick information about a file at a storage path in the backend.
 868          * If the file does not exist, then this returns false.
 869          * Otherwise, the result is an associative array that includes:
 870          *   - mtime  : the last-modified timestamp (TS_MW)
 871          *   - size   : the file size (bytes)
 872          * Additional values may be included for internal use only.
 873          *
 874          * @param $params Array
 875          * $params include:
 876          *   - src    : source storage path
 877          *   - latest : use the latest available data
 878          * @return Array|bool|null Returns null on failure
 879          */
 880         abstract public function getFileStat( array $params );
 881
 882         /**
 883          * Get a SHA-1 hash of the file at a storage path in the backend.
 884          *
 885          * @param $params Array
 886          * $params include:
 887          *   - src    : source storage path
 888          *   - latest : use the latest available data
 889          * @return string|bool Hash string or false on failure
 890          */
 891         abstract public function getFileSha1Base36( array $params );
 892
 893         /**
 894          * Get the properties of the file at a storage path in the backend.
 895          * This gives the result of FSFile::getProps() on a local copy of the file.
 896          *
 897          * @param $params Array
 898          * $params include:
 899          *   - src    : source storage path
 900          *   - latest : use the latest available data
 901          * @return Array Returns FSFile::placeholderProps() on failure
 902          */
 903         abstract public function getFileProps( array $params );
 904
 905         /**
 906          * Stream the file at a storage path in the backend.
 907          * If the file does not exists, an HTTP 404 error will be given.
 908          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
 909          * will be sent if streaming began, while none will be sent otherwise.
 910          * Implementations should flush the output buffer before sending data.
 911          *
 912          * @param $params Array
 913          * $params include:
 914          *   - src     : source storage path
 915          *   - headers : list of additional HTTP headers to send on success
 916          *   - latest  : use the latest available data
 917          * @return Status
 918          */
 919         abstract public function streamFile( array $params );
 920
 921         /**
 922          * Returns a file system file, identical to the file at a storage path.
 923          * The file returned is either:
 924          *   - a) A local copy of the file at a storage path in the backend.
 925          *        The temporary copy will have the same extension as the source.
 926          *   - b) An original of the file at a storage path in the backend.
 927          * Temporary files may be purged when the file object falls out of scope.
 928          *
 929          * Write operations should *never* be done on this file as some backends
 930          * may do internal tracking or may be instances of FileBackendMultiWrite.
 931          * In that later case, there are copies of the file that must stay in sync.
 932          * Additionally, further calls to this function may return the same file.
 933          *
 934          * @param $params Array
 935          * $params include:
 936          *   - src    : source storage path
 937          *   - latest : use the latest available data
 938          * @return FSFile|null Returns null on failure
 939          */
 940         final public function getLocalReference( array $params ) {
 941                 $fsFiles = $this->getLocalReferenceMulti(
 942                         array( 'srcs' => array( $params['src'] ) ) + $params );
 943
 944                 return $fsFiles[$params['src']];
 945         }
 946
 947         /**
 948          * Like getLocalReference() except it takes an array of storage paths
 949          * and returns a map of storage paths to FSFile objects (or null on failure).
 950          * The map keys (paths) are in the same order as the provided list of paths.
 951          *
 952          * @see FileBackend::getLocalReference()
 953          *
 954          * @param $params Array
 955          * $params include:
 956          *   - srcs        : list of source storage paths
 957          *   - latest      : use the latest available data
 958          *   - parallelize : try to do operations in parallel when possible
 959          * @return Array Map of (path name => FSFile or null on failure)
 960          * @since 1.20
 961          */
 962         abstract public function getLocalReferenceMulti( array $params );
 963
 964         /**
 965          * Get a local copy on disk of the file at a storage path in the backend.
 966          * The temporary copy will have the same file extension as the source.
 967          * Temporary files may be purged when the file object falls out of scope.
 968          *
 969          * @param $params Array
 970          * $params include:
 971          *   - src    : source storage path
 972          *   - latest : use the latest available data
 973          * @return TempFSFile|null Returns null on failure
 974          */
 975         final public function getLocalCopy( array $params ) {
 976                 $tmpFiles = $this->getLocalCopyMulti(
 977                         array( 'srcs' => array( $params['src'] ) ) + $params );
 978
 979                 return $tmpFiles[$params['src']];
 980         }
 981
 982         /**
 983          * Like getLocalCopy() except it takes an array of storage paths and
 984          * returns a map of storage paths to TempFSFile objects (or null on failure).
 985          * The map keys (paths) are in the same order as the provided list of paths.
 986          *
 987          * @see FileBackend::getLocalCopy()
 988          *
 989          * @param $params Array
 990          * $params include:
 991          *   - srcs        : list of source storage paths
 992          *   - latest      : use the latest available data
 993          *   - parallelize : try to do operations in parallel when possible
 994          * @return Array Map of (path name => TempFSFile or null on failure)
 995          * @since 1.20
 996          */
 997         abstract public function getLocalCopyMulti( array $params );
 998
 999         /**
1000          * Return an HTTP URL to a given file that requires no authentication to use.
1001          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1002          * This will return null if the backend cannot make an HTTP URL for the file.
1003          *
1004          * This is useful for key/value stores when using scripts that seek around
1005          * large files and those scripts (and the backend) support HTTP Range headers.
1006          * Otherwise, one would need to use getLocalReference(), which involves loading
1007          * the entire file on to local disk.
1008          *
1009          * @param $params Array
1010          * $params include:
1011          *   - src : source storage path
1012          * @return string|null
1013          * @since 1.21
1014          */
1015         abstract public function getFileHttpUrl( array $params );
1016
1017         /**
1018          * Check if a directory exists at a given storage path.
1019          * Backends using key/value stores will check if the path is a
1020          * virtual directory, meaning there are files under the given directory.
1021          *
1022          * Storage backends with eventual consistency might return stale data.
1023          *
1024          * @param $params array
1025          * $params include:
1026          *   - dir : storage directory
1027          * @return bool|null Returns null on failure
1028          * @since 1.20
1029          */
1030         abstract public function directoryExists( array $params );
1031
1032         /**
1033          * Get an iterator to list *all* directories under a storage directory.
1034          * If the directory is of the form "mwstore://backend/container",
1035          * then all directories in the container will be listed.
1036          * If the directory is of form "mwstore://backend/container/dir",
1037          * then all directories directly under that directory will be listed.
1038          * Results will be storage directories relative to the given directory.
1039          *
1040          * Storage backends with eventual consistency might return stale data.
1041          *
1042          * @param $params array
1043          * $params include:
1044          *   - dir     : storage directory
1045          *   - topOnly : only return direct child dirs of the directory
1046          * @return Traversable|Array|null Returns null on failure
1047          * @since 1.20
1048          */
1049         abstract public function getDirectoryList( array $params );
1050
1051         /**
1052          * Same as FileBackend::getDirectoryList() except only lists
1053          * directories that are immediately under the given directory.
1054          *
1055          * Storage backends with eventual consistency might return stale data.
1056          *
1057          * @param $params array
1058          * $params include:
1059          *   - dir : storage directory
1060          * @return Traversable|Array|null Returns null on failure
1061          * @since 1.20
1062          */
1063         final public function getTopDirectoryList( array $params ) {
1064                 return $this->getDirectoryList( array( 'topOnly' => true ) + $params );
1065         }
1066
1067         /**
1068          * Get an iterator to list *all* stored files under a storage directory.
1069          * If the directory is of the form "mwstore://backend/container",
1070          * then all files in the container will be listed.
1071          * If the directory is of form "mwstore://backend/container/dir",
1072          * then all files under that directory will be listed.
1073          * Results will be storage paths relative to the given directory.
1074          *
1075          * Storage backends with eventual consistency might return stale data.
1076          *
1077          * @param $params array
1078          * $params include:
1079          *   - dir     : storage directory
1080          *   - topOnly : only return direct child files of the directory (since 1.20)
1081          * @return Traversable|Array|null Returns null on failure
1082          */
1083         abstract public function getFileList( array $params );
1084
1085         /**
1086          * Same as FileBackend::getFileList() except only lists
1087          * files that are immediately under the given directory.
1088          *
1089          * Storage backends with eventual consistency might return stale data.
1090          *
1091          * @param $params array
1092          * $params include:
1093          *   - dir : storage directory
1094          * @return Traversable|Array|null Returns null on failure
1095          * @since 1.20
1096          */
1097         final public function getTopFileList( array $params ) {
1098                 return $this->getFileList( array( 'topOnly' => true ) + $params );
1099         }
1100
1101         /**
1102          * Preload persistent file stat and property cache into in-process cache.
1103          * This should be used when stat calls will be made on a known list of a many files.
1104          *
1105          * @param $paths Array Storage paths
1106          * @return void
1107          */
1108         public function preloadCache( array $paths ) {}
1109
1110         /**
1111          * Invalidate any in-process file stat and property cache.
1112          * If $paths is given, then only the cache for those files will be cleared.
1113          *
1114          * @param $paths Array Storage paths (optional)
1115          * @return void
1116          */
1117         public function clearCache( array $paths = null ) {}
1118
1119         /**
1120          * Lock the files at the given storage paths in the backend.
1121          * This will either lock all the files or none (on failure).
1122          *
1123          * Callers should consider using getScopedFileLocks() instead.
1124          *
1125          * @param $paths Array Storage paths
1126          * @param $type integer LockManager::LOCK_* constant
1127          * @return Status
1128          */
1129         final public function lockFiles( array $paths, $type ) {
1130                 return $this->lockManager->lock( $paths, $type );
1131         }
1132
1133         /**
1134          * Unlock the files at the given storage paths in the backend.
1135          *
1136          * @param $paths Array Storage paths
1137          * @param $type integer LockManager::LOCK_* constant
1138          * @return Status
1139          */
1140         final public function unlockFiles( array $paths, $type ) {
1141                 return $this->lockManager->unlock( $paths, $type );
1142         }
1143
1144         /**
1145          * Lock the files at the given storage paths in the backend.
1146          * This will either lock all the files or none (on failure).
1147          * On failure, the status object will be updated with errors.
1148          *
1149          * Once the return value goes out scope, the locks will be released and
1150          * the status updated. Unlock fatals will not change the status "OK" value.
1151          *
1152          * @param $paths Array Storage paths
1153          * @param $type integer LockManager::LOCK_* constant
1154          * @param $status Status Status to update on lock/unlock
1155          * @return ScopedLock|null Returns null on failure
1156          */
1157         final public function getScopedFileLocks( array $paths, $type, Status $status ) {
1158                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status );
1159         }
1160
1161         /**
1162          * Get an array of scoped locks needed for a batch of file operations.
1163          *
1164          * Normally, FileBackend::doOperations() handles locking, unless
1165          * the 'nonLocking' param is passed in. This function is useful if you
1166          * want the files to be locked for a broader scope than just when the
1167          * files are changing. For example, if you need to update DB metadata,
1168          * you may want to keep the files locked until finished.
1169          *
1170          * @see FileBackend::doOperations()
1171          *
1172          * @param $ops Array List of file operations to FileBackend::doOperations()
1173          * @param $status Status Status to update on lock/unlock
1174          * @return Array List of ScopedFileLocks or null values
1175          * @since 1.20
1176          */
1177         abstract public function getScopedLocksForOps( array $ops, Status $status );
1178
1179         /**
1180          * Get the root storage path of this backend.
1181          * All container paths are "subdirectories" of this path.
1182          *
1183          * @return string Storage path
1184          * @since 1.20
1185          */
1186         final public function getRootStoragePath() {
1187                 return "mwstore://{$this->name}";
1188         }
1189
1190         /**
1191          * Get the storage path for the given container for this backend
1192          *
1193          * @param $container string Container name
1194          * @return string Storage path
1195          * @since 1.21
1196          */
1197         final public function getContainerStoragePath( $container ) {
1198                 return $this->getRootStoragePath() . "/{$container}";
1199         }
1200
1201         /**
1202          * Get the file journal object for this backend
1203          *
1204          * @return FileJournal
1205          */
1206         final public function getJournal() {
1207                 return $this->fileJournal;
1208         }
1209
1210         /**
1211          * Check if a given path is a "mwstore://" path.
1212          * This does not do any further validation or any existence checks.
1213          *
1214          * @param $path string
1215          * @return bool
1216          */
1217         final public static function isStoragePath( $path ) {
1218                 return ( strpos( $path, 'mwstore://' ) === 0 );
1219         }
1220
1221         /**
1222          * Split a storage path into a backend name, a container name,
1223          * and a relative file path. The relative path may be the empty string.
1224          * This does not do any path normalization or traversal checks.
1225          *
1226          * @param $storagePath string
1227          * @return Array (backend, container, rel object) or (null, null, null)
1228          */
1229         final public static function splitStoragePath( $storagePath ) {
1230                 if ( self::isStoragePath( $storagePath ) ) {
1231                         // Remove the "mwstore://" prefix and split the path
1232                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1233                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1234                                 if ( count( $parts ) == 3 ) {
1235                                         return $parts; // e.g. "backend/container/path"
1236                                 } else {
1237                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
1238                                 }
1239                         }
1240                 }
1241                 return array( null, null, null );
1242         }
1243
1244         /**
1245          * Normalize a storage path by cleaning up directory separators.
1246          * Returns null if the path is not of the format of a valid storage path.
1247          *
1248          * @param $storagePath string
1249          * @return string|null
1250          */
1251         final public static function normalizeStoragePath( $storagePath ) {
1252                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1253                 if ( $relPath !== null ) { // must be for this backend
1254                         $relPath = self::normalizeContainerPath( $relPath );
1255                         if ( $relPath !== null ) {
1256                                 return ( $relPath != '' )
1257                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1258                                         : "mwstore://{$backend}/{$container}";
1259                         }
1260                 }
1261                 return null;
1262         }
1263
1264         /**
1265          * Get the parent storage directory of a storage path.
1266          * This returns a path like "mwstore://backend/container",
1267          * "mwstore://backend/container/...", or null if there is no parent.
1268          *
1269          * @param $storagePath string
1270          * @return string|null
1271          */
1272         final public static function parentStoragePath( $storagePath ) {
1273                 $storagePath = dirname( $storagePath );
1274                 list( $b, $cont, $rel ) = self::splitStoragePath( $storagePath );
1275                 return ( $rel === null ) ? null : $storagePath;
1276         }
1277
1278         /**
1279          * Get the final extension from a storage or FS path
1280          *
1281          * @param $path string
1282          * @return string
1283          */
1284         final public static function extensionFromPath( $path ) {
1285                 $i = strrpos( $path, '.' );
1286                 return strtolower( $i ? substr( $path, $i + 1 ) : '' );
1287         }
1288
1289         /**
1290          * Check if a relative path has no directory traversals
1291          *
1292          * @param $path string
1293          * @return bool
1294          * @since 1.20
1295          */
1296         final public static function isPathTraversalFree( $path ) {
1297                 return ( self::normalizeContainerPath( $path ) !== null );
1298         }
1299
1300         /**
1301          * Build a Content-Disposition header value per RFC 6266.
1302          *
1303          * @param $type string One of (attachment, inline)
1304          * @param $filename string Suggested file name (should not contain slashes)
1305          * @throws MWException
1306          * @return string
1307          * @since 1.20
1308          */
1309         final public static function makeContentDisposition( $type, $filename = '' ) {
1310                 $parts = array();
1311
1312                 $type = strtolower( $type );
1313                 if ( !in_array( $type, array( 'inline', 'attachment' ) ) ) {
1314                         throw new MWException( "Invalid Content-Disposition type '$type'." );
1315                 }
1316                 $parts[] = $type;
1317
1318                 if ( strlen( $filename ) ) {
1319                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1320                 }
1321
1322                 return implode( ';', $parts );
1323         }
1324
1325         /**
1326          * Validate and normalize a relative storage path.
1327          * Null is returned if the path involves directory traversal.
1328          * Traversal is insecure for FS backends and broken for others.
1329          *
1330          * This uses the same traversal protection as Title::secureAndSplit().
1331          *
1332          * @param $path string Storage path relative to a container
1333          * @return string|null
1334          */
1335         final protected static function normalizeContainerPath( $path ) {
1336                 // Normalize directory separators
1337                 $path = strtr( $path, '\\', '/' );
1338                 // Collapse any consecutive directory separators
1339                 $path = preg_replace( '![/]{2,}!', '/', $path );
1340                 // Remove any leading directory separator
1341                 $path = ltrim( $path, '/' );
1342                 // Use the same traversal protection as Title::secureAndSplit()
1343                 if ( strpos( $path, '.' ) !== false ) {
1344                         if (
1345                                 $path === '.' ||
1346                                 $path === '..' ||
1347                                 strpos( $path, './' ) === 0 ||
1348                                 strpos( $path, '../' ) === 0 ||
1349                                 strpos( $path, '/./' ) !== false ||
1350                                 strpos( $path, '/../' ) !== false
1351                         ) {
1352                                 return null;
1353                         }
1354                 }
1355                 return $path;
1356         }
1357 }