includes/filebackend/FileBackend.php

   1 <?php
   2 /**
   3  * @defgroup FileBackend File backend
   4  *
   5  * File backend is used to interact with file storage systems,
   6  * such as the local file system, NFS, or cloud storage systems.
   7  */
   8
   9 /**
  10  * Base class for all file backends.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along
  23  * with this program; if not, write to the Free Software Foundation, Inc.,
  24  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  25  * http://www.gnu.org/copyleft/gpl.html
  26  *
  27  * @file
  28  * @ingroup FileBackend
  29  * @author Aaron Schulz
  30  */
  31
  32 /**
  33  * @brief Base class for all file backend classes (including multi-write backends).
  34  *
  35  * This class defines the methods as abstract that subclasses must implement.
  36  * Outside callers can assume that all backends will have these functions.
  37  *
  38  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
  39  * The "backend" portion is unique name for MediaWiki to refer to a backend, while
  40  * the "container" portion is a top-level directory of the backend. The "path" portion
  41  * is a relative path that uses UNIX file system (FS) notation, though any particular
  42  * backend may not actually be using a local filesystem. Therefore, the relative paths
  43  * are only virtual.
  44  *
  45  * Backend contents are stored under wiki-specific container names by default.
  46  * Global (qualified) backends are achieved by configuring the "wiki ID" to a constant.
  47  * For legacy reasons, the FSFileBackend class allows manually setting the paths of
  48  * containers to ones that do not respect the "wiki ID".
  49  *
  50  * In key/value stores, the container is the only hierarchy (the rest is emulated).
  51  * FS-based backends are somewhat more restrictive due to the existence of real
  52  * directory files; a regular file cannot have the same name as a directory. Other
  53  * backends with virtual directories may not have this limitation. Callers should
  54  * store files in such a way that no files and directories are under the same path.
  55  *
  56  * Methods of subclasses should avoid throwing exceptions at all costs.
  57  * As a corollary, external dependencies should be kept to a minimum.
  58  *
  59  * @ingroup FileBackend
  60  * @since 1.19
  61  */
  62 abstract class FileBackend {
  63         /** @var  string Unique backend name */
  64         protected $name;
  65
  66         /** @var string Unique wiki name */
  67         protected $wikiId;
  68
  69         /** @var string Read-only explanation message */
  70         protected $readOnly;
  71
  72         /** @var string When to do operations in parallel */
  73         protected $parallelize;
  74
  75         /** @var int How many operations can be done in parallel */
  76         protected $concurrency;
  77
  78         /** @var LockManager */
  79         protected $lockManager;
  80
  81         /** @var FileJournal */
  82         protected $fileJournal;
  83
  84         /**
  85          * Create a new backend instance from configuration.
  86          * This should only be called from within FileBackendGroup.
  87          *
  88          * @param array $config Parameters include:
  89          *   - name        : The unique name of this backend.
  90          *                   This should consist of alphanumberic, '-', and '_' characters.
  91          *                   This name should not be changed after use (e.g. with journaling).
  92          *                   Note that the name is *not* used in actual container names.
  93          *   - wikiId      : Prefix to container names that is unique to this backend.
  94          *                   It should only consist of alphanumberic, '-', and '_' characters.
  95          *                   This ID is what avoids collisions if multiple logical backends
  96          *                   use the same storage system, so this should be set carefully.
  97          *   - lockManager : LockManager object to use for any file locking.
  98          *                   If not provided, then no file locking will be enforced.
  99          *   - fileJournal : FileJournal object to use for logging changes to files.
 100          *                   If not provided, then change journaling will be disabled.
 101          *   - readOnly    : Write operations are disallowed if this is a non-empty string.
 102          *                   It should be an explanation for the backend being read-only.
 103          *   - parallelize : When to do file operations in parallel (when possible).
 104          *                   Allowed values are "implicit", "explicit" and "off".
 105          *   - concurrency : How many file operations can be done in parallel.
 106          * @throws MWException
 107          */
 108         public function __construct( array $config ) {
 109                 $this->name = $config['name'];
 110                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 111                         throw new MWException( "Backend name `{$this->name}` is invalid." );
 112                 }
 113                 $this->wikiId = $config['wikiId']; // e.g. "my_wiki-en_"
 114                 $this->lockManager = isset( $config['lockManager'] )
 115                         ? $config['lockManager']
 116                         : new NullLockManager( array() );
 117                 $this->fileJournal = isset( $config['fileJournal'] )
 118                         ? $config['fileJournal']
 119                         : FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
 120                 $this->readOnly = isset( $config['readOnly'] )
 121                         ? (string)$config['readOnly']
 122                         : '';
 123                 $this->parallelize = isset( $config['parallelize'] )
 124                         ? (string)$config['parallelize']
 125                         : 'off';
 126                 $this->concurrency = isset( $config['concurrency'] )
 127                         ? (int)$config['concurrency']
 128                         : 50;
 129         }
 130
 131         /**
 132          * Get the unique backend name.
 133          * We may have multiple different backends of the same type.
 134          * For example, we can have two Swift backends using different proxies.
 135          *
 136          * @return string
 137          */
 138         final public function getName() {
 139                 return $this->name;
 140         }
 141
 142         /**
 143          * Get the wiki identifier used for this backend (possibly empty).
 144          * Note that this might *not* be in the same format as wfWikiID().
 145          *
 146          * @return string
 147          * @since 1.20
 148          */
 149         final public function getWikiId() {
 150                 return $this->wikiId;
 151         }
 152
 153         /**
 154          * Check if this backend is read-only
 155          *
 156          * @return bool
 157          */
 158         final public function isReadOnly() {
 159                 return ( $this->readOnly != '' );
 160         }
 161
 162         /**
 163          * Get an explanatory message if this backend is read-only
 164          *
 165          * @return string|bool Returns false if the backend is not read-only
 166          */
 167         final public function getReadOnlyReason() {
 168                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 169         }
 170
 171         /**
 172          * This is the main entry point into the backend for write operations.
 173          * Callers supply an ordered list of operations to perform as a transaction.
 174          * Files will be locked, the stat cache cleared, and then the operations attempted.
 175          * If any serious errors occur, all attempted operations will be rolled back.
 176          *
 177          * $ops is an array of arrays. The outer array holds a list of operations.
 178          * Each inner array is a set of key value pairs that specify an operation.
 179          *
 180          * Supported operations and their parameters. The supported actions are:
 181          *  - create
 182          *  - store
 183          *  - copy
 184          *  - move
 185          *  - delete
 186          *  - describe (since 1.21)
 187          *  - null
 188          *
 189          * a) Create a new file in storage with the contents of a string
 190          * @code
 191          *     array(
 192          *         'op'                  => 'create',
 193          *         'dst'                 => <storage path>,
 194          *         'content'             => <string of new file contents>,
 195          *         'overwrite'           => <boolean>,
 196          *         'overwriteSame'       => <boolean>,
 197          *         'headers'             => <HTTP header name/value map> # since 1.21
 198          *     );
 199          * @endcode
 200          *
 201          * b) Copy a file system file into storage
 202          * @code
 203          *     array(
 204          *         'op'                  => 'store',
 205          *         'src'                 => <file system path>,
 206          *         'dst'                 => <storage path>,
 207          *         'overwrite'           => <boolean>,
 208          *         'overwriteSame'       => <boolean>,
 209          *         'headers'             => <HTTP header name/value map> # since 1.21
 210          *     )
 211          * @endcode
 212          *
 213          * c) Copy a file within storage
 214          * @code
 215          *     array(
 216          *         'op'                  => 'copy',
 217          *         'src'                 => <storage path>,
 218          *         'dst'                 => <storage path>,
 219          *         'overwrite'           => <boolean>,
 220          *         'overwriteSame'       => <boolean>,
 221          *         'ignoreMissingSource' => <boolean>, # since 1.21
 222          *         'headers'             => <HTTP header name/value map> # since 1.21
 223          *     )
 224          * @endcode
 225          *
 226          * d) Move a file within storage
 227          * @code
 228          *     array(
 229          *         'op'                  => 'move',
 230          *         'src'                 => <storage path>,
 231          *         'dst'                 => <storage path>,
 232          *         'overwrite'           => <boolean>,
 233          *         'overwriteSame'       => <boolean>,
 234          *         'ignoreMissingSource' => <boolean>, # since 1.21
 235          *         'headers'             => <HTTP header name/value map> # since 1.21
 236          *     )
 237          * @endcode
 238          *
 239          * e) Delete a file within storage
 240          * @code
 241          *     array(
 242          *         'op'                  => 'delete',
 243          *         'src'                 => <storage path>,
 244          *         'ignoreMissingSource' => <boolean>
 245          *     )
 246          * @endcode
 247          *
 248          * f) Update metadata for a file within storage
 249          * @code
 250          *     array(
 251          *         'op'                  => 'describe',
 252          *         'src'                 => <storage path>,
 253          *         'headers'             => <HTTP header name/value map>
 254          *     )
 255          * @endcode
 256          *
 257          * g) Do nothing (no-op)
 258          * @code
 259          *     array(
 260          *         'op'                  => 'null',
 261          *     )
 262          * @endcode
 263          *
 264          * Boolean flags for operations (operation-specific):
 265          *   - ignoreMissingSource : The operation will simply succeed and do
 266          *                           nothing if the source file does not exist.
 267          *   - overwrite           : Any destination file will be overwritten.
 268          *   - overwriteSame       : If a file already exists at the destination with the
 269          *                           same contents, then do nothing to the destination file
 270          *                           instead of giving an error. This does not compare headers.
 271          *                           This option is ignored if 'overwrite' is already provided.
 272          *   - headers             : If supplied, the result of merging these headers with any
 273          *                           existing source file headers (replacing conflicting ones)
 274          *                           will be set as the destination file headers. Headers are
 275          *                           deleted if their value is set to the empty string. When a
 276          *                           file has headers they are included in responses to GET and
 277          *                           HEAD requests to the backing store for that file.
 278          *                           Header values should be no larger than 255 bytes, except for
 279          *                           Content-Disposition. The system might ignore or truncate any
 280          *                           headers that are too long to store (exact limits will vary).
 281          *                           Backends that don't support metadata ignore this. (since 1.21)
 282          *
 283          * $opts is an associative of boolean flags, including:
 284          *   - force               : Operation precondition errors no longer trigger an abort.
 285          *                           Any remaining operations are still attempted. Unexpected
 286          *                           failures may still cause remaining operations to be aborted.
 287          *   - nonLocking          : No locks are acquired for the operations.
 288          *                           This can increase performance for non-critical writes.
 289          *                           This has no effect unless the 'force' flag is set.
 290          *   - nonJournaled        : Don't log this operation batch in the file journal.
 291          *                           This limits the ability of recovery scripts.
 292          *   - parallelize         : Try to do operations in parallel when possible.
 293          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 294          *   - preserveCache       : Don't clear the process cache before checking files.
 295          *                           This should only be used if all entries in the process
 296          *                           cache were added after the files were already locked. (since 1.20)
 297          *
 298          * @remarks Remarks on locking:
 299          * File system paths given to operations should refer to files that are
 300          * already locked or otherwise safe from modification from other processes.
 301          * Normally these files will be new temp files, which should be adequate.
 302          *
 303          * @par Return value:
 304          *
 305          * This returns a Status, which contains all warnings and fatals that occurred
 306          * during the operation. The 'failCount', 'successCount', and 'success' members
 307          * will reflect each operation attempted.
 308          *
 309          * The status will be "OK" unless:
 310          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 311          *   - b) significant operation errors occurred and 'force' was not set
 312          *
 313          * @param array $ops List of operations to execute in order
 314          * @param array $opts Batch operation options
 315          * @return Status
 316          */
 317         final public function doOperations( array $ops, array $opts = array() ) {
 318                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 319                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 320                 }
 321                 if ( !count( $ops ) ) {
 322                         return Status::newGood(); // nothing to do
 323                 }
 324                 if ( empty( $opts['force'] ) ) { // sanity
 325                         unset( $opts['nonLocking'] );
 326                 }
 327                 foreach ( $ops as &$op ) {
 328                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 329                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 330                         }
 331                 }
 332                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 333                 return $this->doOperationsInternal( $ops, $opts );
 334         }
 335
 336         /**
 337          * @see FileBackend::doOperations()
 338          */
 339         abstract protected function doOperationsInternal( array $ops, array $opts );
 340
 341         /**
 342          * Same as doOperations() except it takes a single operation.
 343          * If you are doing a batch of operations that should either
 344          * all succeed or all fail, then use that function instead.
 345          *
 346          * @see FileBackend::doOperations()
 347          *
 348          * @param array $op Operation
 349          * @param array $opts Operation options
 350          * @return Status
 351          */
 352         final public function doOperation( array $op, array $opts = array() ) {
 353                 return $this->doOperations( array( $op ), $opts );
 354         }
 355
 356         /**
 357          * Performs a single create operation.
 358          * This sets $params['op'] to 'create' and passes it to doOperation().
 359          *
 360          * @see FileBackend::doOperation()
 361          *
 362          * @param array $params Operation parameters
 363          * @param array $opts Operation options
 364          * @return Status
 365          */
 366         final public function create( array $params, array $opts = array() ) {
 367                 return $this->doOperation( array( 'op' => 'create' ) + $params, $opts );
 368         }
 369
 370         /**
 371          * Performs a single store operation.
 372          * This sets $params['op'] to 'store' and passes it to doOperation().
 373          *
 374          * @see FileBackend::doOperation()
 375          *
 376          * @param array $params Operation parameters
 377          * @param array $opts Operation options
 378          * @return Status
 379          */
 380         final public function store( array $params, array $opts = array() ) {
 381                 return $this->doOperation( array( 'op' => 'store' ) + $params, $opts );
 382         }
 383
 384         /**
 385          * Performs a single copy operation.
 386          * This sets $params['op'] to 'copy' and passes it to doOperation().
 387          *
 388          * @see FileBackend::doOperation()
 389          *
 390          * @param array $params Operation parameters
 391          * @param array $opts Operation options
 392          * @return Status
 393          */
 394         final public function copy( array $params, array $opts = array() ) {
 395                 return $this->doOperation( array( 'op' => 'copy' ) + $params, $opts );
 396         }
 397
 398         /**
 399          * Performs a single move operation.
 400          * This sets $params['op'] to 'move' and passes it to doOperation().
 401          *
 402          * @see FileBackend::doOperation()
 403          *
 404          * @param array $params Operation parameters
 405          * @param array $opts Operation options
 406          * @return Status
 407          */
 408         final public function move( array $params, array $opts = array() ) {
 409                 return $this->doOperation( array( 'op' => 'move' ) + $params, $opts );
 410         }
 411
 412         /**
 413          * Performs a single delete operation.
 414          * This sets $params['op'] to 'delete' and passes it to doOperation().
 415          *
 416          * @see FileBackend::doOperation()
 417          *
 418          * @param array $params Operation parameters
 419          * @param array $opts Operation options
 420          * @return Status
 421          */
 422         final public function delete( array $params, array $opts = array() ) {
 423                 return $this->doOperation( array( 'op' => 'delete' ) + $params, $opts );
 424         }
 425
 426         /**
 427          * Performs a single describe operation.
 428          * This sets $params['op'] to 'describe' and passes it to doOperation().
 429          *
 430          * @see FileBackend::doOperation()
 431          *
 432          * @param array $params Operation parameters
 433          * @param array $opts Operation options
 434          * @return Status
 435          * @since 1.21
 436          */
 437         final public function describe( array $params, array $opts = array() ) {
 438                 return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
 439         }
 440
 441         /**
 442          * Perform a set of independent file operations on some files.
 443          *
 444          * This does no locking, nor journaling, and possibly no stat calls.
 445          * Any destination files that already exist will be overwritten.
 446          * This should *only* be used on non-original files, like cache files.
 447          *
 448          * Supported operations and their parameters:
 449          *  - create
 450          *  - store
 451          *  - copy
 452          *  - move
 453          *  - delete
 454          *  - describe (since 1.21)
 455          *  - null
 456          *
 457          * a) Create a new file in storage with the contents of a string
 458          * @code
 459          *     array(
 460          *         'op'                  => 'create',
 461          *         'dst'                 => <storage path>,
 462          *         'content'             => <string of new file contents>,
 463          *         'headers'             => <HTTP header name/value map> # since 1.21
 464          *     )
 465          * @endcode
 466          *
 467          * b) Copy a file system file into storage
 468          * @code
 469          *     array(
 470          *         'op'                  => 'store',
 471          *         'src'                 => <file system path>,
 472          *         'dst'                 => <storage path>,
 473          *         'headers'             => <HTTP header name/value map> # since 1.21
 474          *     )
 475          * @endcode
 476          *
 477          * c) Copy a file within storage
 478          * @code
 479          *     array(
 480          *         'op'                  => 'copy',
 481          *         'src'                 => <storage path>,
 482          *         'dst'                 => <storage path>,
 483          *         'ignoreMissingSource' => <boolean>, # since 1.21
 484          *         'headers'             => <HTTP header name/value map> # since 1.21
 485          *     )
 486          * @endcode
 487          *
 488          * d) Move a file within storage
 489          * @code
 490          *     array(
 491          *         'op'                  => 'move',
 492          *         'src'                 => <storage path>,
 493          *         'dst'                 => <storage path>,
 494          *         'ignoreMissingSource' => <boolean>, # since 1.21
 495          *         'headers'             => <HTTP header name/value map> # since 1.21
 496          *     )
 497          * @endcode
 498          *
 499          * e) Delete a file within storage
 500          * @code
 501          *     array(
 502          *         'op'                  => 'delete',
 503          *         'src'                 => <storage path>,
 504          *         'ignoreMissingSource' => <boolean>
 505          *     )
 506          * @endcode
 507          *
 508          * f) Update metadata for a file within storage
 509          * @code
 510          *     array(
 511          *         'op'                  => 'describe',
 512          *         'src'                 => <storage path>,
 513          *         'headers'             => <HTTP header name/value map>
 514          *     )
 515          * @endcode
 516          *
 517          * g) Do nothing (no-op)
 518          * @code
 519          *     array(
 520          *         'op'                  => 'null',
 521          *     )
 522          * @endcode
 523          *
 524          * @par Boolean flags for operations (operation-specific):
 525          *   - ignoreMissingSource : The operation will simply succeed and do
 526          *                           nothing if the source file does not exist.
 527          *   - headers             : If supplied with a header name/value map, the backend will
 528          *                           reply with these headers when GETs/HEADs of the destination
 529          *                           file are made. Header values should be smaller than 256 bytes.
 530          *                           Content-Disposition headers can be longer, though the system
 531          *                           might ignore or truncate ones that are too long to store.
 532          *                           Existing headers will remain, but these will replace any
 533          *                           conflicting previous headers, and headers will be removed
 534          *                           if they are set to an empty string.
 535          *                           Backends that don't support metadata ignore this. (since 1.21)
 536          *
 537          * $opts is an associative of boolean flags, including:
 538          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 539          *
 540          * @par Return value:
 541          * This returns a Status, which contains all warnings and fatals that occurred
 542          * during the operation. The 'failCount', 'successCount', and 'success' members
 543          * will reflect each operation attempted for the given files. The status will be
 544          * considered "OK" as long as no fatal errors occurred.
 545          *
 546          * @param array $ops Set of operations to execute
 547          * @param array $opts Batch operation options
 548          * @return Status
 549          * @since 1.20
 550          */
 551         final public function doQuickOperations( array $ops, array $opts = array() ) {
 552                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 553                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 554                 }
 555                 if ( !count( $ops ) ) {
 556                         return Status::newGood(); // nothing to do
 557                 }
 558                 foreach ( $ops as &$op ) {
 559                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 560                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 561                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 562                         }
 563                 }
 564                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 565                 return $this->doQuickOperationsInternal( $ops );
 566         }
 567
 568         /**
 569          * @see FileBackend::doQuickOperations()
 570          * @since 1.20
 571          */
 572         abstract protected function doQuickOperationsInternal( array $ops );
 573
 574         /**
 575          * Same as doQuickOperations() except it takes a single operation.
 576          * If you are doing a batch of operations, then use that function instead.
 577          *
 578          * @see FileBackend::doQuickOperations()
 579          *
 580          * @param array $op Operation
 581          * @return Status
 582          * @since 1.20
 583          */
 584         final public function doQuickOperation( array $op ) {
 585                 return $this->doQuickOperations( array( $op ) );
 586         }
 587
 588         /**
 589          * Performs a single quick create operation.
 590          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 591          *
 592          * @see FileBackend::doQuickOperation()
 593          *
 594          * @param array $params Operation parameters
 595          * @return Status
 596          * @since 1.20
 597          */
 598         final public function quickCreate( array $params ) {
 599                 return $this->doQuickOperation( array( 'op' => 'create' ) + $params );
 600         }
 601
 602         /**
 603          * Performs a single quick store operation.
 604          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 605          *
 606          * @see FileBackend::doQuickOperation()
 607          *
 608          * @param array $params Operation parameters
 609          * @return Status
 610          * @since 1.20
 611          */
 612         final public function quickStore( array $params ) {
 613                 return $this->doQuickOperation( array( 'op' => 'store' ) + $params );
 614         }
 615
 616         /**
 617          * Performs a single quick copy operation.
 618          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 619          *
 620          * @see FileBackend::doQuickOperation()
 621          *
 622          * @param array $params Operation parameters
 623          * @return Status
 624          * @since 1.20
 625          */
 626         final public function quickCopy( array $params ) {
 627                 return $this->doQuickOperation( array( 'op' => 'copy' ) + $params );
 628         }
 629
 630         /**
 631          * Performs a single quick move operation.
 632          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 633          *
 634          * @see FileBackend::doQuickOperation()
 635          *
 636          * @param array $params Operation parameters
 637          * @return Status
 638          * @since 1.20
 639          */
 640         final public function quickMove( array $params ) {
 641                 return $this->doQuickOperation( array( 'op' => 'move' ) + $params );
 642         }
 643
 644         /**
 645          * Performs a single quick delete operation.
 646          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 647          *
 648          * @see FileBackend::doQuickOperation()
 649          *
 650          * @param array $params Operation parameters
 651          * @return Status
 652          * @since 1.20
 653          */
 654         final public function quickDelete( array $params ) {
 655                 return $this->doQuickOperation( array( 'op' => 'delete' ) + $params );
 656         }
 657
 658         /**
 659          * Performs a single quick describe operation.
 660          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 661          *
 662          * @see FileBackend::doQuickOperation()
 663          *
 664          * @param array $params Operation parameters
 665          * @return Status
 666          * @since 1.21
 667          */
 668         final public function quickDescribe( array $params ) {
 669                 return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
 670         }
 671
 672         /**
 673          * Concatenate a list of storage files into a single file system file.
 674          * The target path should refer to a file that is already locked or
 675          * otherwise safe from modification from other processes. Normally,
 676          * the file will be a new temp file, which should be adequate.
 677          *
 678          * @param array $params Operation parameters, include:
 679          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 680          *   - dst         : file system path to 0-byte temp file
 681          *   - parallelize : try to do operations in parallel when possible
 682          * @return Status
 683          */
 684         abstract public function concatenate( array $params );
 685
 686         /**
 687          * Prepare a storage directory for usage.
 688          * This will create any required containers and parent directories.
 689          * Backends using key/value stores only need to create the container.
 690          *
 691          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 692          * except they are only applied *if* the directory/container had to be created.
 693          * These flags should always be set for directories that have private files.
 694          * However, setting them is not guaranteed to actually do anything.
 695          * Additional server configuration may be needed to achieve the desired effect.
 696          *
 697          * @param array $params Parameters include:
 698          *   - dir            : storage directory
 699          *   - noAccess       : try to deny file access (since 1.20)
 700          *   - noListing      : try to deny file listing (since 1.20)
 701          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 702          * @return Status
 703          */
 704         final public function prepare( array $params ) {
 705                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 706                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 707                 }
 708                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 709                 return $this->doPrepare( $params );
 710         }
 711
 712         /**
 713          * @see FileBackend::prepare()
 714          */
 715         abstract protected function doPrepare( array $params );
 716
 717         /**
 718          * Take measures to block web access to a storage directory and
 719          * the container it belongs to. FS backends might add .htaccess
 720          * files whereas key/value store backends might revoke container
 721          * access to the storage user representing end-users in web requests.
 722          *
 723          * This is not guaranteed to actually make files or listings publically hidden.
 724          * Additional server configuration may be needed to achieve the desired effect.
 725          *
 726          * @param array $params Parameters include:
 727          *   - dir            : storage directory
 728          *   - noAccess       : try to deny file access
 729          *   - noListing      : try to deny file listing
 730          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 731          * @return Status
 732          */
 733         final public function secure( array $params ) {
 734                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 735                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 736                 }
 737                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 738                 return $this->doSecure( $params );
 739         }
 740
 741         /**
 742          * @see FileBackend::secure()
 743          */
 744         abstract protected function doSecure( array $params );
 745
 746         /**
 747          * Remove measures to block web access to a storage directory and
 748          * the container it belongs to. FS backends might remove .htaccess
 749          * files whereas key/value store backends might grant container
 750          * access to the storage user representing end-users in web requests.
 751          * This essentially can undo the result of secure() calls.
 752          *
 753          * This is not guaranteed to actually make files or listings publically viewable.
 754          * Additional server configuration may be needed to achieve the desired effect.
 755          *
 756          * @param array $params Parameters include:
 757          *   - dir            : storage directory
 758          *   - access         : try to allow file access
 759          *   - listing        : try to allow file listing
 760          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 761          * @return Status
 762          * @since 1.20
 763          */
 764         final public function publish( array $params ) {
 765                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 766                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 767                 }
 768                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 769                 return $this->doPublish( $params );
 770         }
 771
 772         /**
 773          * @see FileBackend::publish()
 774          */
 775         abstract protected function doPublish( array $params );
 776
 777         /**
 778          * Delete a storage directory if it is empty.
 779          * Backends using key/value stores may do nothing unless the directory
 780          * is that of an empty container, in which case it will be deleted.
 781          *
 782          * @param array $params Parameters include:
 783          *   - dir            : storage directory
 784          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 785          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 786          * @return Status
 787          */
 788         final public function clean( array $params ) {
 789                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 790                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 791                 }
 792                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 793                 return $this->doClean( $params );
 794         }
 795
 796         /**
 797          * @see FileBackend::clean()
 798          */
 799         abstract protected function doClean( array $params );
 800
 801         /**
 802          * Enter file operation scope.
 803          * This just makes PHP ignore user aborts/disconnects until the return
 804          * value leaves scope. This returns null and does nothing in CLI mode.
 805          *
 806          * @return ScopedCallback|null
 807          */
 808         final protected function getScopedPHPBehaviorForOps() {
 809                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 810                         $old = ignore_user_abort( true ); // avoid half-finished operations
 811                         return new ScopedCallback( function () use ( $old ) {
 812                                 ignore_user_abort( $old );
 813                         } );
 814                 }
 815
 816                 return null;
 817         }
 818
 819         /**
 820          * Check if a file exists at a storage path in the backend.
 821          * This returns false if only a directory exists at the path.
 822          *
 823          * @param array $params Parameters include:
 824          *   - src    : source storage path
 825          *   - latest : use the latest available data
 826          * @return bool|null Returns null on failure
 827          */
 828         abstract public function fileExists( array $params );
 829
 830         /**
 831          * Get the last-modified timestamp of the file at a storage path.
 832          *
 833          * @param array $params Parameters include:
 834          *   - src    : source storage path
 835          *   - latest : use the latest available data
 836          * @return string|bool TS_MW timestamp or false on failure
 837          */
 838         abstract public function getFileTimestamp( array $params );
 839
 840         /**
 841          * Get the contents of a file at a storage path in the backend.
 842          * This should be avoided for potentially large files.
 843          *
 844          * @param array $params Parameters include:
 845          *   - src    : source storage path
 846          *   - latest : use the latest available data
 847          * @return string|bool Returns false on failure
 848          */
 849         final public function getFileContents( array $params ) {
 850                 $contents = $this->getFileContentsMulti(
 851                         array( 'srcs' => array( $params['src'] ) ) + $params );
 852
 853                 return $contents[$params['src']];
 854         }
 855
 856         /**
 857          * Like getFileContents() except it takes an array of storage paths
 858          * and returns a map of storage paths to strings (or null on failure).
 859          * The map keys (paths) are in the same order as the provided list of paths.
 860          *
 861          * @see FileBackend::getFileContents()
 862          *
 863          * @param array $params Parameters include:
 864          *   - srcs        : list of source storage paths
 865          *   - latest      : use the latest available data
 866          *   - parallelize : try to do operations in parallel when possible
 867          * @return array Map of (path name => string or false on failure)
 868          * @since 1.20
 869          */
 870         abstract public function getFileContentsMulti( array $params );
 871
 872         /**
 873          * Get the size (bytes) of a file at a storage path in the backend.
 874          *
 875          * @param array $params Parameters include:
 876          *   - src    : source storage path
 877          *   - latest : use the latest available data
 878          * @return int|bool Returns false on failure
 879          */
 880         abstract public function getFileSize( array $params );
 881
 882         /**
 883          * Get quick information about a file at a storage path in the backend.
 884          * If the file does not exist, then this returns false.
 885          * Otherwise, the result is an associative array that includes:
 886          *   - mtime  : the last-modified timestamp (TS_MW)
 887          *   - size   : the file size (bytes)
 888          * Additional values may be included for internal use only.
 889          *
 890          * @param array $params Parameters include:
 891          *   - src    : source storage path
 892          *   - latest : use the latest available data
 893          * @return array|bool|null Returns null on failure
 894          */
 895         abstract public function getFileStat( array $params );
 896
 897         /**
 898          * Get a SHA-1 hash of the file at a storage path in the backend.
 899          *
 900          * @param array $params Parameters include:
 901          *   - src    : source storage path
 902          *   - latest : use the latest available data
 903          * @return string|bool Hash string or false on failure
 904          */
 905         abstract public function getFileSha1Base36( array $params );
 906
 907         /**
 908          * Get the properties of the file at a storage path in the backend.
 909          * This gives the result of FSFile::getProps() on a local copy of the file.
 910          *
 911          * @param array $params Parameters include:
 912          *   - src    : source storage path
 913          *   - latest : use the latest available data
 914          * @return array Returns FSFile::placeholderProps() on failure
 915          */
 916         abstract public function getFileProps( array $params );
 917
 918         /**
 919          * Stream the file at a storage path in the backend.
 920          * If the file does not exists, an HTTP 404 error will be given.
 921          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
 922          * will be sent if streaming began, while none will be sent otherwise.
 923          * Implementations should flush the output buffer before sending data.
 924          *
 925          * @param array $params Parameters include:
 926          *   - src     : source storage path
 927          *   - headers : list of additional HTTP headers to send on success
 928          *   - latest  : use the latest available data
 929          * @return Status
 930          */
 931         abstract public function streamFile( array $params );
 932
 933         /**
 934          * Returns a file system file, identical to the file at a storage path.
 935          * The file returned is either:
 936          *   - a) A local copy of the file at a storage path in the backend.
 937          *        The temporary copy will have the same extension as the source.
 938          *   - b) An original of the file at a storage path in the backend.
 939          * Temporary files may be purged when the file object falls out of scope.
 940          *
 941          * Write operations should *never* be done on this file as some backends
 942          * may do internal tracking or may be instances of FileBackendMultiWrite.
 943          * In that later case, there are copies of the file that must stay in sync.
 944          * Additionally, further calls to this function may return the same file.
 945          *
 946          * @param array $params Parameters include:
 947          *   - src    : source storage path
 948          *   - latest : use the latest available data
 949          * @return FSFile|null Returns null on failure
 950          */
 951         final public function getLocalReference( array $params ) {
 952                 $fsFiles = $this->getLocalReferenceMulti(
 953                         array( 'srcs' => array( $params['src'] ) ) + $params );
 954
 955                 return $fsFiles[$params['src']];
 956         }
 957
 958         /**
 959          * Like getLocalReference() except it takes an array of storage paths
 960          * and returns a map of storage paths to FSFile objects (or null on failure).
 961          * The map keys (paths) are in the same order as the provided list of paths.
 962          *
 963          * @see FileBackend::getLocalReference()
 964          *
 965          * @param array $params Parameters include:
 966          *   - srcs        : list of source storage paths
 967          *   - latest      : use the latest available data
 968          *   - parallelize : try to do operations in parallel when possible
 969          * @return array Map of (path name => FSFile or null on failure)
 970          * @since 1.20
 971          */
 972         abstract public function getLocalReferenceMulti( array $params );
 973
 974         /**
 975          * Get a local copy on disk of the file at a storage path in the backend.
 976          * The temporary copy will have the same file extension as the source.
 977          * Temporary files may be purged when the file object falls out of scope.
 978          *
 979          * @param array $params Parameters include:
 980          *   - src    : source storage path
 981          *   - latest : use the latest available data
 982          * @return TempFSFile|null Returns null on failure
 983          */
 984         final public function getLocalCopy( array $params ) {
 985                 $tmpFiles = $this->getLocalCopyMulti(
 986                         array( 'srcs' => array( $params['src'] ) ) + $params );
 987
 988                 return $tmpFiles[$params['src']];
 989         }
 990
 991         /**
 992          * Like getLocalCopy() except it takes an array of storage paths and
 993          * returns a map of storage paths to TempFSFile objects (or null on failure).
 994          * The map keys (paths) are in the same order as the provided list of paths.
 995          *
 996          * @see FileBackend::getLocalCopy()
 997          *
 998          * @param array $params Parameters include:
 999          *   - srcs        : list of source storage paths
1000          *   - latest      : use the latest available data
1001          *   - parallelize : try to do operations in parallel when possible
1002          * @return array Map of (path name => TempFSFile or null on failure)
1003          * @since 1.20
1004          */
1005         abstract public function getLocalCopyMulti( array $params );
1006
1007         /**
1008          * Return an HTTP URL to a given file that requires no authentication to use.
1009          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1010          * This will return null if the backend cannot make an HTTP URL for the file.
1011          *
1012          * This is useful for key/value stores when using scripts that seek around
1013          * large files and those scripts (and the backend) support HTTP Range headers.
1014          * Otherwise, one would need to use getLocalReference(), which involves loading
1015          * the entire file on to local disk.
1016          *
1017          * @param array $params Parameters include:
1018          *   - src : source storage path
1019          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1020          * @return string|null
1021          * @since 1.21
1022          */
1023         abstract public function getFileHttpUrl( array $params );
1024
1025         /**
1026          * Check if a directory exists at a given storage path.
1027          * Backends using key/value stores will check if the path is a
1028          * virtual directory, meaning there are files under the given directory.
1029          *
1030          * Storage backends with eventual consistency might return stale data.
1031          *
1032          * @param array $params Parameters include:
1033          *   - dir : storage directory
1034          * @return bool|null Returns null on failure
1035          * @since 1.20
1036          */
1037         abstract public function directoryExists( array $params );
1038
1039         /**
1040          * Get an iterator to list *all* directories under a storage directory.
1041          * If the directory is of the form "mwstore://backend/container",
1042          * then all directories in the container will be listed.
1043          * If the directory is of form "mwstore://backend/container/dir",
1044          * then all directories directly under that directory will be listed.
1045          * Results will be storage directories relative to the given directory.
1046          *
1047          * Storage backends with eventual consistency might return stale data.
1048          *
1049          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1050          *
1051          * @param array $params Parameters include:
1052          *   - dir     : storage directory
1053          *   - topOnly : only return direct child dirs of the directory
1054          * @return Traversable|Array|null Returns null on failure
1055          * @since 1.20
1056          */
1057         abstract public function getDirectoryList( array $params );
1058
1059         /**
1060          * Same as FileBackend::getDirectoryList() except only lists
1061          * directories that are immediately under the given directory.
1062          *
1063          * Storage backends with eventual consistency might return stale data.
1064          *
1065          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1066          *
1067          * @param array $params Parameters include:
1068          *   - dir : storage directory
1069          * @return Traversable|Array|null Returns null on failure
1070          * @since 1.20
1071          */
1072         final public function getTopDirectoryList( array $params ) {
1073                 return $this->getDirectoryList( array( 'topOnly' => true ) + $params );
1074         }
1075
1076         /**
1077          * Get an iterator to list *all* stored files under a storage directory.
1078          * If the directory is of the form "mwstore://backend/container",
1079          * then all files in the container will be listed.
1080          * If the directory is of form "mwstore://backend/container/dir",
1081          * then all files under that directory will be listed.
1082          * Results will be storage paths relative to the given directory.
1083          *
1084          * Storage backends with eventual consistency might return stale data.
1085          *
1086          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1087          *
1088          * @param array $params Parameters include:
1089          *   - dir        : storage directory
1090          *   - topOnly    : only return direct child files of the directory (since 1.20)
1091          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1092          * @return Traversable|Array|null Returns null on failure
1093          */
1094         abstract public function getFileList( array $params );
1095
1096         /**
1097          * Same as FileBackend::getFileList() except only lists
1098          * files that are immediately under the given directory.
1099          *
1100          * Storage backends with eventual consistency might return stale data.
1101          *
1102          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1103          *
1104          * @param array $params Parameters include:
1105          *   - dir        : storage directory
1106          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1107          * @return Traversable|Array|null Returns null on failure
1108          * @since 1.20
1109          */
1110         final public function getTopFileList( array $params ) {
1111                 return $this->getFileList( array( 'topOnly' => true ) + $params );
1112         }
1113
1114         /**
1115          * Preload persistent file stat and property cache into in-process cache.
1116          * This should be used when stat calls will be made on a known list of a many files.
1117          *
1118          * @param array $paths Storage paths
1119          */
1120         public function preloadCache( array $paths ) {
1121         }
1122
1123         /**
1124          * Invalidate any in-process file stat and property cache.
1125          * If $paths is given, then only the cache for those files will be cleared.
1126          *
1127          * @param array $paths Storage paths (optional)
1128          */
1129         public function clearCache( array $paths = null ) {
1130         }
1131
1132         /**
1133          * Lock the files at the given storage paths in the backend.
1134          * This will either lock all the files or none (on failure).
1135          *
1136          * Callers should consider using getScopedFileLocks() instead.
1137          *
1138          * @param array $paths Storage paths
1139          * @param int $type LockManager::LOCK_* constant
1140          * @return Status
1141          */
1142         final public function lockFiles( array $paths, $type ) {
1143                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1144
1145                 return $this->lockManager->lock( $paths, $type );
1146         }
1147
1148         /**
1149          * Unlock the files at the given storage paths in the backend.
1150          *
1151          * @param array $paths Storage paths
1152          * @param int $type LockManager::LOCK_* constant
1153          * @return Status
1154          */
1155         final public function unlockFiles( array $paths, $type ) {
1156                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1157
1158                 return $this->lockManager->unlock( $paths, $type );
1159         }
1160
1161         /**
1162          * Lock the files at the given storage paths in the backend.
1163          * This will either lock all the files or none (on failure).
1164          * On failure, the status object will be updated with errors.
1165          *
1166          * Once the return value goes out scope, the locks will be released and
1167          * the status updated. Unlock fatals will not change the status "OK" value.
1168          *
1169          * @see ScopedLock::factory()
1170          *
1171          * @param array $paths List of storage paths or map of lock types to path lists
1172          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1173          * @param Status $status Status to update on lock/unlock
1174          * @return ScopedLock|null Returns null on failure
1175          */
1176         final public function getScopedFileLocks( array $paths, $type, Status $status ) {
1177                 if ( $type === 'mixed' ) {
1178                         foreach ( $paths as &$typePaths ) {
1179                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1180                         }
1181                 } else {
1182                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1183                 }
1184
1185                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status );
1186         }
1187
1188         /**
1189          * Get an array of scoped locks needed for a batch of file operations.
1190          *
1191          * Normally, FileBackend::doOperations() handles locking, unless
1192          * the 'nonLocking' param is passed in. This function is useful if you
1193          * want the files to be locked for a broader scope than just when the
1194          * files are changing. For example, if you need to update DB metadata,
1195          * you may want to keep the files locked until finished.
1196          *
1197          * @see FileBackend::doOperations()
1198          *
1199          * @param array $ops List of file operations to FileBackend::doOperations()
1200          * @param Status $status Status to update on lock/unlock
1201          * @return array List of ScopedFileLocks or null values
1202          * @since 1.20
1203          */
1204         abstract public function getScopedLocksForOps( array $ops, Status $status );
1205
1206         /**
1207          * Get the root storage path of this backend.
1208          * All container paths are "subdirectories" of this path.
1209          *
1210          * @return string Storage path
1211          * @since 1.20
1212          */
1213         final public function getRootStoragePath() {
1214                 return "mwstore://{$this->name}";
1215         }
1216
1217         /**
1218          * Get the storage path for the given container for this backend
1219          *
1220          * @param string $container Container name
1221          * @return string Storage path
1222          * @since 1.21
1223          */
1224         final public function getContainerStoragePath( $container ) {
1225                 return $this->getRootStoragePath() . "/{$container}";
1226         }
1227
1228         /**
1229          * Get the file journal object for this backend
1230          *
1231          * @return FileJournal
1232          */
1233         final public function getJournal() {
1234                 return $this->fileJournal;
1235         }
1236
1237         /**
1238          * Check if a given path is a "mwstore://" path.
1239          * This does not do any further validation or any existence checks.
1240          *
1241          * @param string $path
1242          * @return bool
1243          */
1244         final public static function isStoragePath( $path ) {
1245                 return ( strpos( $path, 'mwstore://' ) === 0 );
1246         }
1247
1248         /**
1249          * Split a storage path into a backend name, a container name,
1250          * and a relative file path. The relative path may be the empty string.
1251          * This does not do any path normalization or traversal checks.
1252          *
1253          * @param string $storagePath
1254          * @return array (backend, container, rel object) or (null, null, null)
1255          */
1256         final public static function splitStoragePath( $storagePath ) {
1257                 if ( self::isStoragePath( $storagePath ) ) {
1258                         // Remove the "mwstore://" prefix and split the path
1259                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1260                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1261                                 if ( count( $parts ) == 3 ) {
1262                                         return $parts; // e.g. "backend/container/path"
1263                                 } else {
1264                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
1265                                 }
1266                         }
1267                 }
1268
1269                 return array( null, null, null );
1270         }
1271
1272         /**
1273          * Normalize a storage path by cleaning up directory separators.
1274          * Returns null if the path is not of the format of a valid storage path.
1275          *
1276          * @param string $storagePath
1277          * @return string|null
1278          */
1279         final public static function normalizeStoragePath( $storagePath ) {
1280                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1281                 if ( $relPath !== null ) { // must be for this backend
1282                         $relPath = self::normalizeContainerPath( $relPath );
1283                         if ( $relPath !== null ) {
1284                                 return ( $relPath != '' )
1285                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1286                                         : "mwstore://{$backend}/{$container}";
1287                         }
1288                 }
1289
1290                 return null;
1291         }
1292
1293         /**
1294          * Get the parent storage directory of a storage path.
1295          * This returns a path like "mwstore://backend/container",
1296          * "mwstore://backend/container/...", or null if there is no parent.
1297          *
1298          * @param string $storagePath
1299          * @return string|null
1300          */
1301         final public static function parentStoragePath( $storagePath ) {
1302                 $storagePath = dirname( $storagePath );
1303                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1304
1305                 return ( $rel === null ) ? null : $storagePath;
1306         }
1307
1308         /**
1309          * Get the final extension from a storage or FS path
1310          *
1311          * @param string $path
1312          * @return string
1313          */
1314         final public static function extensionFromPath( $path ) {
1315                 $i = strrpos( $path, '.' );
1316
1317                 return strtolower( $i ? substr( $path, $i + 1 ) : '' );
1318         }
1319
1320         /**
1321          * Check if a relative path has no directory traversals
1322          *
1323          * @param string $path
1324          * @return bool
1325          * @since 1.20
1326          */
1327         final public static function isPathTraversalFree( $path ) {
1328                 return ( self::normalizeContainerPath( $path ) !== null );
1329         }
1330
1331         /**
1332          * Build a Content-Disposition header value per RFC 6266.
1333          *
1334          * @param string $type One of (attachment, inline)
1335          * @param string $filename Suggested file name (should not contain slashes)
1336          * @throws MWException
1337          * @return string
1338          * @since 1.20
1339          */
1340         final public static function makeContentDisposition( $type, $filename = '' ) {
1341                 $parts = array();
1342
1343                 $type = strtolower( $type );
1344                 if ( !in_array( $type, array( 'inline', 'attachment' ) ) ) {
1345                         throw new MWException( "Invalid Content-Disposition type '$type'." );
1346                 }
1347                 $parts[] = $type;
1348
1349                 if ( strlen( $filename ) ) {
1350                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1351                 }
1352
1353                 return implode( ';', $parts );
1354         }
1355
1356         /**
1357          * Validate and normalize a relative storage path.
1358          * Null is returned if the path involves directory traversal.
1359          * Traversal is insecure for FS backends and broken for others.
1360          *
1361          * This uses the same traversal protection as Title::secureAndSplit().
1362          *
1363          * @param string $path Storage path relative to a container
1364          * @return string|null
1365          */
1366         final protected static function normalizeContainerPath( $path ) {
1367                 // Normalize directory separators
1368                 $path = strtr( $path, '\\', '/' );
1369                 // Collapse any consecutive directory separators
1370                 $path = preg_replace( '![/]{2,}!', '/', $path );
1371                 // Remove any leading directory separator
1372                 $path = ltrim( $path, '/' );
1373                 // Use the same traversal protection as Title::secureAndSplit()
1374                 if ( strpos( $path, '.' ) !== false ) {
1375                         if (
1376                                 $path === '.' ||
1377                                 $path === '..' ||
1378                                 strpos( $path, './' ) === 0 ||
1379                                 strpos( $path, '../' ) === 0 ||
1380                                 strpos( $path, '/./' ) !== false ||
1381                                 strpos( $path, '/../' ) !== false
1382                         ) {
1383                                 return null;
1384                         }
1385                 }
1386
1387                 return $path;
1388         }
1389 }
1390
1391 /**
1392  * @ingroup FileBackend
1393  * @since 1.22
1394  */
1395 class FileBackendError extends MWException {
1396 }