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