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 (object) stores, containers are 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  * In general, this class allows for callers to access storage through the same
  57  * interface, without regard to the underlying storage system. However, calling code
  58  * must follow certain patterns and be aware of certain things to ensure compatibility:
  59  *   - a) Always call prepare() on the parent directory before trying to put a file there;
  60  *        key/value stores only need the container to exist first, but filesystems need
  61  *        all the parent directories to exist first (prepare() is aware of all this)
  62  *   - b) Always call clean() on a directory when it might become empty to avoid empty
  63  *        directory buildup on filesystems; key/value stores never have empty directories,
  64  *        so doing this helps preserve consistency in both cases
  65  *   - c) Likewise, do not rely on the existence of empty directories for anything;
  66  *        calling directoryExists() on a path that prepare() was previously called on
  67  *        will return false for key/value stores if there are no files under that path
  68  *   - d) Never alter the resulting FSFile returned from getLocalReference(), as it could
  69  *        either be a copy of the source file in /tmp or the original source file itself
  70  *   - e) Use a file layout that results in never attempting to store files over directories
  71  *        or directories over files; key/value stores allow this but filesystems do not
  72  *   - f) Use ASCII file names (e.g. base32, IDs, hashes) to avoid Unicode issues in Windows
  73  *   - g) Do not assume that move operations are atomic (difficult with key/value stores)
  74  *   - h) Do not assume that file stat or read operations always have immediate consistency;
  75  *        various methods have a "latest" flag that should always be used if up-to-date
  76  *        information is required (this trades performance for correctness as needed)
  77  *   - i) Do not assume that directory listings have immediate consistency
  78  *
  79  * Methods of subclasses should avoid throwing exceptions at all costs.
  80  * As a corollary, external dependencies should be kept to a minimum.
  81  *
  82  * @ingroup FileBackend
  83  * @since 1.19
  84  */
  85 abstract class FileBackend {
  86         /** @var string Unique backend name */
  87         protected $name;
  88
  89         /** @var string Unique wiki name */
  90         protected $wikiId;
  91
  92         /** @var string Read-only explanation message */
  93         protected $readOnly;
  94
  95         /** @var string When to do operations in parallel */
  96         protected $parallelize;
  97
  98         /** @var int How many operations can be done in parallel */
  99         protected $concurrency;
 100
 101         /** @var LockManager */
 102         protected $lockManager;
 103
 104         /** @var FileJournal */
 105         protected $fileJournal;
 106
 107         /** Bitfield flags for supported features */
 108         const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
 109         const ATTR_METADATA = 2; // files can be stored with metadata key/values
 110         const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
 111
 112         /**
 113          * Create a new backend instance from configuration.
 114          * This should only be called from within FileBackendGroup.
 115          *
 116          * @param array $config Parameters include:
 117          *   - name        : The unique name of this backend.
 118          *                   This should consist of alphanumberic, '-', and '_' characters.
 119          *                   This name should not be changed after use (e.g. with journaling).
 120          *                   Note that the name is *not* used in actual container names.
 121          *   - wikiId      : Prefix to container names that is unique to this backend.
 122          *                   It should only consist of alphanumberic, '-', and '_' characters.
 123          *                   This ID is what avoids collisions if multiple logical backends
 124          *                   use the same storage system, so this should be set carefully.
 125          *   - lockManager : LockManager object to use for any file locking.
 126          *                   If not provided, then no file locking will be enforced.
 127          *   - fileJournal : FileJournal object to use for logging changes to files.
 128          *                   If not provided, then change journaling will be disabled.
 129          *   - readOnly    : Write operations are disallowed if this is a non-empty string.
 130          *                   It should be an explanation for the backend being read-only.
 131          *   - parallelize : When to do file operations in parallel (when possible).
 132          *                   Allowed values are "implicit", "explicit" and "off".
 133          *   - concurrency : How many file operations can be done in parallel.
 134          * @throws FileBackendException
 135          */
 136         public function __construct( array $config ) {
 137                 $this->name = $config['name'];
 138                 $this->wikiId = $config['wikiId']; // e.g. "my_wiki-en_"
 139                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 140                         throw new FileBackendException( "Backend name '{$this->name}' is invalid." );
 141                 } elseif ( !is_string( $this->wikiId ) ) {
 142                         throw new FileBackendException( "Backend wiki ID not provided for '{$this->name}'." );
 143                 }
 144                 $this->lockManager = isset( $config['lockManager'] )
 145                         ? $config['lockManager']
 146                         : new NullLockManager( array() );
 147                 $this->fileJournal = isset( $config['fileJournal'] )
 148                         ? $config['fileJournal']
 149                         : FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
 150                 $this->readOnly = isset( $config['readOnly'] )
 151                         ? (string)$config['readOnly']
 152                         : '';
 153                 $this->parallelize = isset( $config['parallelize'] )
 154                         ? (string)$config['parallelize']
 155                         : 'off';
 156                 $this->concurrency = isset( $config['concurrency'] )
 157                         ? (int)$config['concurrency']
 158                         : 50;
 159         }
 160
 161         /**
 162          * Get the unique backend name.
 163          * We may have multiple different backends of the same type.
 164          * For example, we can have two Swift backends using different proxies.
 165          *
 166          * @return string
 167          */
 168         final public function getName() {
 169                 return $this->name;
 170         }
 171
 172         /**
 173          * Get the wiki identifier used for this backend (possibly empty).
 174          * Note that this might *not* be in the same format as wfWikiID().
 175          *
 176          * @return string
 177          * @since 1.20
 178          */
 179         final public function getWikiId() {
 180                 return $this->wikiId;
 181         }
 182
 183         /**
 184          * Check if this backend is read-only
 185          *
 186          * @return bool
 187          */
 188         final public function isReadOnly() {
 189                 return ( $this->readOnly != '' );
 190         }
 191
 192         /**
 193          * Get an explanatory message if this backend is read-only
 194          *
 195          * @return string|bool Returns false if the backend is not read-only
 196          */
 197         final public function getReadOnlyReason() {
 198                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 199         }
 200
 201         /**
 202          * Get the a bitfield of extra features supported by the backend medium
 203          *
 204          * @return int Bitfield of FileBackend::ATTR_* flags
 205          * @since 1.23
 206          */
 207         public function getFeatures() {
 208                 return self::ATTR_UNICODE_PATHS;
 209         }
 210
 211         /**
 212          * Check if the backend medium supports a field of extra features
 213          *
 214          * @param int $bitfield Bitfield of FileBackend::ATTR_* flags
 215          * @return bool
 216          * @since 1.23
 217          */
 218         final public function hasFeatures( $bitfield ) {
 219                 return ( $this->getFeatures() & $bitfield ) === $bitfield;
 220         }
 221
 222         /**
 223          * This is the main entry point into the backend for write operations.
 224          * Callers supply an ordered list of operations to perform as a transaction.
 225          * Files will be locked, the stat cache cleared, and then the operations attempted.
 226          * If any serious errors occur, all attempted operations will be rolled back.
 227          *
 228          * $ops is an array of arrays. The outer array holds a list of operations.
 229          * Each inner array is a set of key value pairs that specify an operation.
 230          *
 231          * Supported operations and their parameters. The supported actions are:
 232          *  - create
 233          *  - store
 234          *  - copy
 235          *  - move
 236          *  - delete
 237          *  - describe (since 1.21)
 238          *  - null
 239          *
 240          * a) Create a new file in storage with the contents of a string
 241          * @code
 242          *     array(
 243          *         'op'                  => 'create',
 244          *         'dst'                 => <storage path>,
 245          *         'content'             => <string of new file contents>,
 246          *         'overwrite'           => <boolean>,
 247          *         'overwriteSame'       => <boolean>,
 248          *         'headers'             => <HTTP header name/value map> # since 1.21
 249          *     );
 250          * @endcode
 251          *
 252          * b) Copy a file system file into storage
 253          * @code
 254          *     array(
 255          *         'op'                  => 'store',
 256          *         'src'                 => <file system path>,
 257          *         'dst'                 => <storage path>,
 258          *         'overwrite'           => <boolean>,
 259          *         'overwriteSame'       => <boolean>,
 260          *         'headers'             => <HTTP header name/value map> # since 1.21
 261          *     )
 262          * @endcode
 263          *
 264          * c) Copy a file within storage
 265          * @code
 266          *     array(
 267          *         'op'                  => 'copy',
 268          *         'src'                 => <storage path>,
 269          *         'dst'                 => <storage path>,
 270          *         'overwrite'           => <boolean>,
 271          *         'overwriteSame'       => <boolean>,
 272          *         'ignoreMissingSource' => <boolean>, # since 1.21
 273          *         'headers'             => <HTTP header name/value map> # since 1.21
 274          *     )
 275          * @endcode
 276          *
 277          * d) Move a file within storage
 278          * @code
 279          *     array(
 280          *         'op'                  => 'move',
 281          *         'src'                 => <storage path>,
 282          *         'dst'                 => <storage path>,
 283          *         'overwrite'           => <boolean>,
 284          *         'overwriteSame'       => <boolean>,
 285          *         'ignoreMissingSource' => <boolean>, # since 1.21
 286          *         'headers'             => <HTTP header name/value map> # since 1.21
 287          *     )
 288          * @endcode
 289          *
 290          * e) Delete a file within storage
 291          * @code
 292          *     array(
 293          *         'op'                  => 'delete',
 294          *         'src'                 => <storage path>,
 295          *         'ignoreMissingSource' => <boolean>
 296          *     )
 297          * @endcode
 298          *
 299          * f) Update metadata for a file within storage
 300          * @code
 301          *     array(
 302          *         'op'                  => 'describe',
 303          *         'src'                 => <storage path>,
 304          *         'headers'             => <HTTP header name/value map>
 305          *     )
 306          * @endcode
 307          *
 308          * g) Do nothing (no-op)
 309          * @code
 310          *     array(
 311          *         'op'                  => 'null',
 312          *     )
 313          * @endcode
 314          *
 315          * Boolean flags for operations (operation-specific):
 316          *   - ignoreMissingSource : The operation will simply succeed and do
 317          *                           nothing if the source file does not exist.
 318          *   - overwrite           : Any destination file will be overwritten.
 319          *   - overwriteSame       : If a file already exists at the destination with the
 320          *                           same contents, then do nothing to the destination file
 321          *                           instead of giving an error. This does not compare headers.
 322          *                           This option is ignored if 'overwrite' is already provided.
 323          *   - headers             : If supplied, the result of merging these headers with any
 324          *                           existing source file headers (replacing conflicting ones)
 325          *                           will be set as the destination file headers. Headers are
 326          *                           deleted if their value is set to the empty string. When a
 327          *                           file has headers they are included in responses to GET and
 328          *                           HEAD requests to the backing store for that file.
 329          *                           Header values should be no larger than 255 bytes, except for
 330          *                           Content-Disposition. The system might ignore or truncate any
 331          *                           headers that are too long to store (exact limits will vary).
 332          *                           Backends that don't support metadata ignore this. (since 1.21)
 333          *
 334          * $opts is an associative of boolean flags, including:
 335          *   - force               : Operation precondition errors no longer trigger an abort.
 336          *                           Any remaining operations are still attempted. Unexpected
 337          *                           failures may still cause remaining operations to be aborted.
 338          *   - nonLocking          : No locks are acquired for the operations.
 339          *                           This can increase performance for non-critical writes.
 340          *                           This has no effect unless the 'force' flag is set.
 341          *   - nonJournaled        : Don't log this operation batch in the file journal.
 342          *                           This limits the ability of recovery scripts.
 343          *   - parallelize         : Try to do operations in parallel when possible.
 344          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 345          *   - preserveCache       : Don't clear the process cache before checking files.
 346          *                           This should only be used if all entries in the process
 347          *                           cache were added after the files were already locked. (since 1.20)
 348          *
 349          * @remarks Remarks on locking:
 350          * File system paths given to operations should refer to files that are
 351          * already locked or otherwise safe from modification from other processes.
 352          * Normally these files will be new temp files, which should be adequate.
 353          *
 354          * @par Return value:
 355          *
 356          * This returns a Status, which contains all warnings and fatals that occurred
 357          * during the operation. The 'failCount', 'successCount', and 'success' members
 358          * will reflect each operation attempted.
 359          *
 360          * The status will be "OK" unless:
 361          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 362          *   - b) significant operation errors occurred and 'force' was not set
 363          *
 364          * @param array $ops List of operations to execute in order
 365          * @param array $opts Batch operation options
 366          * @return Status
 367          */
 368         final public function doOperations( array $ops, array $opts = array() ) {
 369                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 370                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 371                 }
 372                 if ( !count( $ops ) ) {
 373                         return Status::newGood(); // nothing to do
 374                 }
 375                 if ( empty( $opts['force'] ) ) { // sanity
 376                         unset( $opts['nonLocking'] );
 377                 }
 378                 foreach ( $ops as &$op ) {
 379                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 380                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 381                         }
 382                 }
 383                 /** @noinspection PhpUnusedLocalVariableInspection */
 384                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 385                 return $this->doOperationsInternal( $ops, $opts );
 386         }
 387
 388         /**
 389          * @see FileBackend::doOperations()
 390          * @param array $ops
 391          * @param array $opts
 392          */
 393         abstract protected function doOperationsInternal( array $ops, array $opts );
 394
 395         /**
 396          * Same as doOperations() except it takes a single operation.
 397          * If you are doing a batch of operations that should either
 398          * all succeed or all fail, then use that function instead.
 399          *
 400          * @see FileBackend::doOperations()
 401          *
 402          * @param array $op Operation
 403          * @param array $opts Operation options
 404          * @return Status
 405          */
 406         final public function doOperation( array $op, array $opts = array() ) {
 407                 return $this->doOperations( array( $op ), $opts );
 408         }
 409
 410         /**
 411          * Performs a single create operation.
 412          * This sets $params['op'] to 'create' and passes it to doOperation().
 413          *
 414          * @see FileBackend::doOperation()
 415          *
 416          * @param array $params Operation parameters
 417          * @param array $opts Operation options
 418          * @return Status
 419          */
 420         final public function create( array $params, array $opts = array() ) {
 421                 return $this->doOperation( array( 'op' => 'create' ) + $params, $opts );
 422         }
 423
 424         /**
 425          * Performs a single store operation.
 426          * This sets $params['op'] to 'store' and passes it to doOperation().
 427          *
 428          * @see FileBackend::doOperation()
 429          *
 430          * @param array $params Operation parameters
 431          * @param array $opts Operation options
 432          * @return Status
 433          */
 434         final public function store( array $params, array $opts = array() ) {
 435                 return $this->doOperation( array( 'op' => 'store' ) + $params, $opts );
 436         }
 437
 438         /**
 439          * Performs a single copy operation.
 440          * This sets $params['op'] to 'copy' and passes it to doOperation().
 441          *
 442          * @see FileBackend::doOperation()
 443          *
 444          * @param array $params Operation parameters
 445          * @param array $opts Operation options
 446          * @return Status
 447          */
 448         final public function copy( array $params, array $opts = array() ) {
 449                 return $this->doOperation( array( 'op' => 'copy' ) + $params, $opts );
 450         }
 451
 452         /**
 453          * Performs a single move operation.
 454          * This sets $params['op'] to 'move' and passes it to doOperation().
 455          *
 456          * @see FileBackend::doOperation()
 457          *
 458          * @param array $params Operation parameters
 459          * @param array $opts Operation options
 460          * @return Status
 461          */
 462         final public function move( array $params, array $opts = array() ) {
 463                 return $this->doOperation( array( 'op' => 'move' ) + $params, $opts );
 464         }
 465
 466         /**
 467          * Performs a single delete operation.
 468          * This sets $params['op'] to 'delete' and passes it to doOperation().
 469          *
 470          * @see FileBackend::doOperation()
 471          *
 472          * @param array $params Operation parameters
 473          * @param array $opts Operation options
 474          * @return Status
 475          */
 476         final public function delete( array $params, array $opts = array() ) {
 477                 return $this->doOperation( array( 'op' => 'delete' ) + $params, $opts );
 478         }
 479
 480         /**
 481          * Performs a single describe operation.
 482          * This sets $params['op'] to 'describe' and passes it to doOperation().
 483          *
 484          * @see FileBackend::doOperation()
 485          *
 486          * @param array $params Operation parameters
 487          * @param array $opts Operation options
 488          * @return Status
 489          * @since 1.21
 490          */
 491         final public function describe( array $params, array $opts = array() ) {
 492                 return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
 493         }
 494
 495         /**
 496          * Perform a set of independent file operations on some files.
 497          *
 498          * This does no locking, nor journaling, and possibly no stat calls.
 499          * Any destination files that already exist will be overwritten.
 500          * This should *only* be used on non-original files, like cache files.
 501          *
 502          * Supported operations and their parameters:
 503          *  - create
 504          *  - store
 505          *  - copy
 506          *  - move
 507          *  - delete
 508          *  - describe (since 1.21)
 509          *  - null
 510          *
 511          * a) Create a new file in storage with the contents of a string
 512          * @code
 513          *     array(
 514          *         'op'                  => 'create',
 515          *         'dst'                 => <storage path>,
 516          *         'content'             => <string of new file contents>,
 517          *         'headers'             => <HTTP header name/value map> # since 1.21
 518          *     )
 519          * @endcode
 520          *
 521          * b) Copy a file system file into storage
 522          * @code
 523          *     array(
 524          *         'op'                  => 'store',
 525          *         'src'                 => <file system path>,
 526          *         'dst'                 => <storage path>,
 527          *         'headers'             => <HTTP header name/value map> # since 1.21
 528          *     )
 529          * @endcode
 530          *
 531          * c) Copy a file within storage
 532          * @code
 533          *     array(
 534          *         'op'                  => 'copy',
 535          *         'src'                 => <storage path>,
 536          *         'dst'                 => <storage path>,
 537          *         'ignoreMissingSource' => <boolean>, # since 1.21
 538          *         'headers'             => <HTTP header name/value map> # since 1.21
 539          *     )
 540          * @endcode
 541          *
 542          * d) Move a file within storage
 543          * @code
 544          *     array(
 545          *         'op'                  => 'move',
 546          *         'src'                 => <storage path>,
 547          *         'dst'                 => <storage path>,
 548          *         'ignoreMissingSource' => <boolean>, # since 1.21
 549          *         'headers'             => <HTTP header name/value map> # since 1.21
 550          *     )
 551          * @endcode
 552          *
 553          * e) Delete a file within storage
 554          * @code
 555          *     array(
 556          *         'op'                  => 'delete',
 557          *         'src'                 => <storage path>,
 558          *         'ignoreMissingSource' => <boolean>
 559          *     )
 560          * @endcode
 561          *
 562          * f) Update metadata for a file within storage
 563          * @code
 564          *     array(
 565          *         'op'                  => 'describe',
 566          *         'src'                 => <storage path>,
 567          *         'headers'             => <HTTP header name/value map>
 568          *     )
 569          * @endcode
 570          *
 571          * g) Do nothing (no-op)
 572          * @code
 573          *     array(
 574          *         'op'                  => 'null',
 575          *     )
 576          * @endcode
 577          *
 578          * @par Boolean flags for operations (operation-specific):
 579          *   - ignoreMissingSource : The operation will simply succeed and do
 580          *                           nothing if the source file does not exist.
 581          *   - headers             : If supplied with a header name/value map, the backend will
 582          *                           reply with these headers when GETs/HEADs of the destination
 583          *                           file are made. Header values should be smaller than 256 bytes.
 584          *                           Content-Disposition headers can be longer, though the system
 585          *                           might ignore or truncate ones that are too long to store.
 586          *                           Existing headers will remain, but these will replace any
 587          *                           conflicting previous headers, and headers will be removed
 588          *                           if they are set to an empty string.
 589          *                           Backends that don't support metadata ignore this. (since 1.21)
 590          *
 591          * $opts is an associative of boolean flags, including:
 592          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 593          *
 594          * @par Return value:
 595          * This returns a Status, which contains all warnings and fatals that occurred
 596          * during the operation. The 'failCount', 'successCount', and 'success' members
 597          * will reflect each operation attempted for the given files. The status will be
 598          * considered "OK" as long as no fatal errors occurred.
 599          *
 600          * @param array $ops Set of operations to execute
 601          * @param array $opts Batch operation options
 602          * @return Status
 603          * @since 1.20
 604          */
 605         final public function doQuickOperations( array $ops, array $opts = array() ) {
 606                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 607                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 608                 }
 609                 if ( !count( $ops ) ) {
 610                         return Status::newGood(); // nothing to do
 611                 }
 612                 foreach ( $ops as &$op ) {
 613                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 614                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 615                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 616                         }
 617                 }
 618                 /** @noinspection PhpUnusedLocalVariableInspection */
 619                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 620                 return $this->doQuickOperationsInternal( $ops );
 621         }
 622
 623         /**
 624          * @see FileBackend::doQuickOperations()
 625          * @param array $ops
 626          * @since 1.20
 627          */
 628         abstract protected function doQuickOperationsInternal( array $ops );
 629
 630         /**
 631          * Same as doQuickOperations() except it takes a single operation.
 632          * If you are doing a batch of operations, then use that function instead.
 633          *
 634          * @see FileBackend::doQuickOperations()
 635          *
 636          * @param array $op Operation
 637          * @return Status
 638          * @since 1.20
 639          */
 640         final public function doQuickOperation( array $op ) {
 641                 return $this->doQuickOperations( array( $op ) );
 642         }
 643
 644         /**
 645          * Performs a single quick create operation.
 646          * This sets $params['op'] to 'create' 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 quickCreate( array $params ) {
 655                 return $this->doQuickOperation( array( 'op' => 'create' ) + $params );
 656         }
 657
 658         /**
 659          * Performs a single quick store operation.
 660          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 661          *
 662          * @see FileBackend::doQuickOperation()
 663          *
 664          * @param array $params Operation parameters
 665          * @return Status
 666          * @since 1.20
 667          */
 668         final public function quickStore( array $params ) {
 669                 return $this->doQuickOperation( array( 'op' => 'store' ) + $params );
 670         }
 671
 672         /**
 673          * Performs a single quick copy operation.
 674          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 675          *
 676          * @see FileBackend::doQuickOperation()
 677          *
 678          * @param array $params Operation parameters
 679          * @return Status
 680          * @since 1.20
 681          */
 682         final public function quickCopy( array $params ) {
 683                 return $this->doQuickOperation( array( 'op' => 'copy' ) + $params );
 684         }
 685
 686         /**
 687          * Performs a single quick move operation.
 688          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 689          *
 690          * @see FileBackend::doQuickOperation()
 691          *
 692          * @param array $params Operation parameters
 693          * @return Status
 694          * @since 1.20
 695          */
 696         final public function quickMove( array $params ) {
 697                 return $this->doQuickOperation( array( 'op' => 'move' ) + $params );
 698         }
 699
 700         /**
 701          * Performs a single quick delete operation.
 702          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 703          *
 704          * @see FileBackend::doQuickOperation()
 705          *
 706          * @param array $params Operation parameters
 707          * @return Status
 708          * @since 1.20
 709          */
 710         final public function quickDelete( array $params ) {
 711                 return $this->doQuickOperation( array( 'op' => 'delete' ) + $params );
 712         }
 713
 714         /**
 715          * Performs a single quick describe operation.
 716          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 717          *
 718          * @see FileBackend::doQuickOperation()
 719          *
 720          * @param array $params Operation parameters
 721          * @return Status
 722          * @since 1.21
 723          */
 724         final public function quickDescribe( array $params ) {
 725                 return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
 726         }
 727
 728         /**
 729          * Concatenate a list of storage files into a single file system file.
 730          * The target path should refer to a file that is already locked or
 731          * otherwise safe from modification from other processes. Normally,
 732          * the file will be a new temp file, which should be adequate.
 733          *
 734          * @param array $params Operation parameters, include:
 735          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 736          *   - dst         : file system path to 0-byte temp file
 737          *   - parallelize : try to do operations in parallel when possible
 738          * @return Status
 739          */
 740         abstract public function concatenate( array $params );
 741
 742         /**
 743          * Prepare a storage directory for usage.
 744          * This will create any required containers and parent directories.
 745          * Backends using key/value stores only need to create the container.
 746          *
 747          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 748          * except they are only applied *if* the directory/container had to be created.
 749          * These flags should always be set for directories that have private files.
 750          * However, setting them is not guaranteed to actually do anything.
 751          * Additional server configuration may be needed to achieve the desired effect.
 752          *
 753          * @param array $params Parameters include:
 754          *   - dir            : storage directory
 755          *   - noAccess       : try to deny file access (since 1.20)
 756          *   - noListing      : try to deny file listing (since 1.20)
 757          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 758          * @return Status
 759          */
 760         final public function prepare( array $params ) {
 761                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 762                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 763                 }
 764                 /** @noinspection PhpUnusedLocalVariableInspection */
 765                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 766                 return $this->doPrepare( $params );
 767         }
 768
 769         /**
 770          * @see FileBackend::prepare()
 771          * @param array $params
 772          */
 773         abstract protected function doPrepare( array $params );
 774
 775         /**
 776          * Take measures to block web access to a storage directory and
 777          * the container it belongs to. FS backends might add .htaccess
 778          * files whereas key/value store backends might revoke container
 779          * access to the storage user representing end-users in web requests.
 780          *
 781          * This is not guaranteed to actually make files or listings publically hidden.
 782          * Additional server configuration may be needed to achieve the desired effect.
 783          *
 784          * @param array $params Parameters include:
 785          *   - dir            : storage directory
 786          *   - noAccess       : try to deny file access
 787          *   - noListing      : try to deny file listing
 788          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 789          * @return Status
 790          */
 791         final public function secure( array $params ) {
 792                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 793                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 794                 }
 795                 /** @noinspection PhpUnusedLocalVariableInspection */
 796                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 797                 return $this->doSecure( $params );
 798         }
 799
 800         /**
 801          * @see FileBackend::secure()
 802          * @param array $params
 803          */
 804         abstract protected function doSecure( array $params );
 805
 806         /**
 807          * Remove measures to block web access to a storage directory and
 808          * the container it belongs to. FS backends might remove .htaccess
 809          * files whereas key/value store backends might grant container
 810          * access to the storage user representing end-users in web requests.
 811          * This essentially can undo the result of secure() calls.
 812          *
 813          * This is not guaranteed to actually make files or listings publically viewable.
 814          * Additional server configuration may be needed to achieve the desired effect.
 815          *
 816          * @param array $params Parameters include:
 817          *   - dir            : storage directory
 818          *   - access         : try to allow file access
 819          *   - listing        : try to allow file listing
 820          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 821          * @return Status
 822          * @since 1.20
 823          */
 824         final public function publish( array $params ) {
 825                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 826                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 827                 }
 828                 /** @noinspection PhpUnusedLocalVariableInspection */
 829                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 830                 return $this->doPublish( $params );
 831         }
 832
 833         /**
 834          * @see FileBackend::publish()
 835          * @param array $params
 836          */
 837         abstract protected function doPublish( array $params );
 838
 839         /**
 840          * Delete a storage directory if it is empty.
 841          * Backends using key/value stores may do nothing unless the directory
 842          * is that of an empty container, in which case it will be deleted.
 843          *
 844          * @param array $params Parameters include:
 845          *   - dir            : storage directory
 846          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 847          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 848          * @return Status
 849          */
 850         final public function clean( array $params ) {
 851                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 852                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 853                 }
 854                 /** @noinspection PhpUnusedLocalVariableInspection */
 855                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 856                 return $this->doClean( $params );
 857         }
 858
 859         /**
 860          * @see FileBackend::clean()
 861          * @param array $params
 862          */
 863         abstract protected function doClean( array $params );
 864
 865         /**
 866          * Enter file operation scope.
 867          * This just makes PHP ignore user aborts/disconnects until the return
 868          * value leaves scope. This returns null and does nothing in CLI mode.
 869          *
 870          * @return ScopedCallback|null
 871          */
 872         final protected function getScopedPHPBehaviorForOps() {
 873                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 874                         $old = ignore_user_abort( true ); // avoid half-finished operations
 875                         return new ScopedCallback( function () use ( $old ) {
 876                                 ignore_user_abort( $old );
 877                         } );
 878                 }
 879
 880                 return null;
 881         }
 882
 883         /**
 884          * Check if a file exists at a storage path in the backend.
 885          * This returns false if only a directory exists at the path.
 886          *
 887          * @param array $params Parameters include:
 888          *   - src    : source storage path
 889          *   - latest : use the latest available data
 890          * @return bool|null Returns null on failure
 891          */
 892         abstract public function fileExists( array $params );
 893
 894         /**
 895          * Get the last-modified timestamp of the file at a storage path.
 896          *
 897          * @param array $params Parameters include:
 898          *   - src    : source storage path
 899          *   - latest : use the latest available data
 900          * @return string|bool TS_MW timestamp or false on failure
 901          */
 902         abstract public function getFileTimestamp( array $params );
 903
 904         /**
 905          * Get the contents of a file at a storage path in the backend.
 906          * This should be avoided for potentially large files.
 907          *
 908          * @param array $params Parameters include:
 909          *   - src    : source storage path
 910          *   - latest : use the latest available data
 911          * @return string|bool Returns false on failure
 912          */
 913         final public function getFileContents( array $params ) {
 914                 $contents = $this->getFileContentsMulti(
 915                         array( 'srcs' => array( $params['src'] ) ) + $params );
 916
 917                 return $contents[$params['src']];
 918         }
 919
 920         /**
 921          * Like getFileContents() except it takes an array of storage paths
 922          * and returns a map of storage paths to strings (or null on failure).
 923          * The map keys (paths) are in the same order as the provided list of paths.
 924          *
 925          * @see FileBackend::getFileContents()
 926          *
 927          * @param array $params Parameters include:
 928          *   - srcs        : list of source storage paths
 929          *   - latest      : use the latest available data
 930          *   - parallelize : try to do operations in parallel when possible
 931          * @return array Map of (path name => string or false on failure)
 932          * @since 1.20
 933          */
 934         abstract public function getFileContentsMulti( array $params );
 935
 936         /**
 937          * Get metadata about a file at a storage path in the backend.
 938          * If the file does not exist, then this returns false.
 939          * Otherwise, the result is an associative array that includes:
 940          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 941          *   - metadata : map of file metadata (name => value)
 942          * Metadata keys and headers names will be returned in all lower-case.
 943          * Additional values may be included for internal use only.
 944          *
 945          * Use FileBackend::hasFeatures() to check how well this is supported.
 946          *
 947          * @param array $params
 948          * $params include:
 949          *   - src    : source storage path
 950          *   - latest : use the latest available data
 951          * @return array|bool Returns false on failure
 952          * @since 1.23
 953          */
 954         abstract public function getFileXAttributes( array $params );
 955
 956         /**
 957          * Get the size (bytes) of a file at a storage path in the backend.
 958          *
 959          * @param array $params Parameters include:
 960          *   - src    : source storage path
 961          *   - latest : use the latest available data
 962          * @return int|bool Returns false on failure
 963          */
 964         abstract public function getFileSize( array $params );
 965
 966         /**
 967          * Get quick information about a file at a storage path in the backend.
 968          * If the file does not exist, then this returns false.
 969          * Otherwise, the result is an associative array that includes:
 970          *   - mtime  : the last-modified timestamp (TS_MW)
 971          *   - size   : the file size (bytes)
 972          * Additional values may be included for internal use only.
 973          *
 974          * @param array $params Parameters include:
 975          *   - src    : source storage path
 976          *   - latest : use the latest available data
 977          * @return array|bool|null Returns null on failure
 978          */
 979         abstract public function getFileStat( array $params );
 980
 981         /**
 982          * Get a SHA-1 hash of the file at a storage path in the backend.
 983          *
 984          * @param array $params Parameters include:
 985          *   - src    : source storage path
 986          *   - latest : use the latest available data
 987          * @return string|bool Hash string or false on failure
 988          */
 989         abstract public function getFileSha1Base36( array $params );
 990
 991         /**
 992          * Get the properties of the file at a storage path in the backend.
 993          * This gives the result of FSFile::getProps() on a local copy of the file.
 994          *
 995          * @param array $params Parameters include:
 996          *   - src    : source storage path
 997          *   - latest : use the latest available data
 998          * @return array Returns FSFile::placeholderProps() on failure
 999          */
1000         abstract public function getFileProps( array $params );
1001
1002         /**
1003          * Stream the file at a storage path in the backend.
1004          * If the file does not exists, an HTTP 404 error will be given.
1005          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
1006          * will be sent if streaming began, while none will be sent otherwise.
1007          * Implementations should flush the output buffer before sending data.
1008          *
1009          * @param array $params Parameters include:
1010          *   - src     : source storage path
1011          *   - headers : list of additional HTTP headers to send on success
1012          *   - latest  : use the latest available data
1013          * @return Status
1014          */
1015         abstract public function streamFile( array $params );
1016
1017         /**
1018          * Returns a file system file, identical to the file at a storage path.
1019          * The file returned is either:
1020          *   - a) A local copy of the file at a storage path in the backend.
1021          *        The temporary copy will have the same extension as the source.
1022          *   - b) An original of the file at a storage path in the backend.
1023          * Temporary files may be purged when the file object falls out of scope.
1024          *
1025          * Write operations should *never* be done on this file as some backends
1026          * may do internal tracking or may be instances of FileBackendMultiWrite.
1027          * In that later case, there are copies of the file that must stay in sync.
1028          * Additionally, further calls to this function may return the same file.
1029          *
1030          * @param array $params Parameters include:
1031          *   - src    : source storage path
1032          *   - latest : use the latest available data
1033          * @return FSFile|null Returns null on failure
1034          */
1035         final public function getLocalReference( array $params ) {
1036                 $fsFiles = $this->getLocalReferenceMulti(
1037                         array( 'srcs' => array( $params['src'] ) ) + $params );
1038
1039                 return $fsFiles[$params['src']];
1040         }
1041
1042         /**
1043          * Like getLocalReference() except it takes an array of storage paths
1044          * and returns a map of storage paths to FSFile objects (or null on failure).
1045          * The map keys (paths) are in the same order as the provided list of paths.
1046          *
1047          * @see FileBackend::getLocalReference()
1048          *
1049          * @param array $params Parameters include:
1050          *   - srcs        : list of source storage paths
1051          *   - latest      : use the latest available data
1052          *   - parallelize : try to do operations in parallel when possible
1053          * @return array Map of (path name => FSFile or null on failure)
1054          * @since 1.20
1055          */
1056         abstract public function getLocalReferenceMulti( array $params );
1057
1058         /**
1059          * Get a local copy on disk of the file at a storage path in the backend.
1060          * The temporary copy will have the same file extension as the source.
1061          * Temporary files may be purged when the file object falls out of scope.
1062          *
1063          * @param array $params Parameters include:
1064          *   - src    : source storage path
1065          *   - latest : use the latest available data
1066          * @return TempFSFile|null Returns null on failure
1067          */
1068         final public function getLocalCopy( array $params ) {
1069                 $tmpFiles = $this->getLocalCopyMulti(
1070                         array( 'srcs' => array( $params['src'] ) ) + $params );
1071
1072                 return $tmpFiles[$params['src']];
1073         }
1074
1075         /**
1076          * Like getLocalCopy() except it takes an array of storage paths and
1077          * returns a map of storage paths to TempFSFile objects (or null on failure).
1078          * The map keys (paths) are in the same order as the provided list of paths.
1079          *
1080          * @see FileBackend::getLocalCopy()
1081          *
1082          * @param array $params Parameters include:
1083          *   - srcs        : list of source storage paths
1084          *   - latest      : use the latest available data
1085          *   - parallelize : try to do operations in parallel when possible
1086          * @return array Map of (path name => TempFSFile or null on failure)
1087          * @since 1.20
1088          */
1089         abstract public function getLocalCopyMulti( array $params );
1090
1091         /**
1092          * Return an HTTP URL to a given file that requires no authentication to use.
1093          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1094          * This will return null if the backend cannot make an HTTP URL for the file.
1095          *
1096          * This is useful for key/value stores when using scripts that seek around
1097          * large files and those scripts (and the backend) support HTTP Range headers.
1098          * Otherwise, one would need to use getLocalReference(), which involves loading
1099          * the entire file on to local disk.
1100          *
1101          * @param array $params Parameters include:
1102          *   - src : source storage path
1103          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1104          * @return string|null
1105          * @since 1.21
1106          */
1107         abstract public function getFileHttpUrl( array $params );
1108
1109         /**
1110          * Check if a directory exists at a given storage path.
1111          * Backends using key/value stores will check if the path is a
1112          * virtual directory, meaning there are files under the given directory.
1113          *
1114          * Storage backends with eventual consistency might return stale data.
1115          *
1116          * @param array $params Parameters include:
1117          *   - dir : storage directory
1118          * @return bool|null Returns null on failure
1119          * @since 1.20
1120          */
1121         abstract public function directoryExists( array $params );
1122
1123         /**
1124          * Get an iterator to list *all* directories under a storage directory.
1125          * If the directory is of the form "mwstore://backend/container",
1126          * then all directories in the container will be listed.
1127          * If the directory is of form "mwstore://backend/container/dir",
1128          * then all directories directly under that directory will be listed.
1129          * Results will be storage directories relative to the given directory.
1130          *
1131          * Storage backends with eventual consistency might return stale data.
1132          *
1133          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1134          *
1135          * @param array $params Parameters include:
1136          *   - dir     : storage directory
1137          *   - topOnly : only return direct child dirs of the directory
1138          * @return Traversable|array|null Returns null on failure
1139          * @since 1.20
1140          */
1141         abstract public function getDirectoryList( array $params );
1142
1143         /**
1144          * Same as FileBackend::getDirectoryList() except only lists
1145          * directories that are immediately under the given directory.
1146          *
1147          * Storage backends with eventual consistency might return stale data.
1148          *
1149          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1150          *
1151          * @param array $params Parameters include:
1152          *   - dir : storage directory
1153          * @return Traversable|array|null Returns null on failure
1154          * @since 1.20
1155          */
1156         final public function getTopDirectoryList( array $params ) {
1157                 return $this->getDirectoryList( array( 'topOnly' => true ) + $params );
1158         }
1159
1160         /**
1161          * Get an iterator to list *all* stored files under a storage directory.
1162          * If the directory is of the form "mwstore://backend/container",
1163          * then all files in the container will be listed.
1164          * If the directory is of form "mwstore://backend/container/dir",
1165          * then all files under that directory will be listed.
1166          * Results will be storage paths relative to the given directory.
1167          *
1168          * Storage backends with eventual consistency might return stale data.
1169          *
1170          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1171          *
1172          * @param array $params Parameters include:
1173          *   - dir        : storage directory
1174          *   - topOnly    : only return direct child files of the directory (since 1.20)
1175          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1176          * @return Traversable|array|null Returns null on failure
1177          */
1178         abstract public function getFileList( array $params );
1179
1180         /**
1181          * Same as FileBackend::getFileList() except only lists
1182          * files that are immediately under the given directory.
1183          *
1184          * Storage backends with eventual consistency might return stale data.
1185          *
1186          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1187          *
1188          * @param array $params Parameters include:
1189          *   - dir        : storage directory
1190          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1191          * @return Traversable|array|null Returns null on failure
1192          * @since 1.20
1193          */
1194         final public function getTopFileList( array $params ) {
1195                 return $this->getFileList( array( 'topOnly' => true ) + $params );
1196         }
1197
1198         /**
1199          * Preload persistent file stat cache and property cache into in-process cache.
1200          * This should be used when stat calls will be made on a known list of a many files.
1201          *
1202          * @see FileBackend::getFileStat()
1203          *
1204          * @param array $paths Storage paths
1205          */
1206         abstract public function preloadCache( array $paths );
1207
1208         /**
1209          * Invalidate any in-process file stat and property cache.
1210          * If $paths is given, then only the cache for those files will be cleared.
1211          *
1212          * @see FileBackend::getFileStat()
1213          *
1214          * @param array $paths Storage paths (optional)
1215          */
1216         abstract public function clearCache( array $paths = null );
1217
1218         /**
1219          * Preload file stat information (concurrently if possible) into in-process cache.
1220          *
1221          * This should be used when stat calls will be made on a known list of a many files.
1222          * This does not make use of the persistent file stat cache.
1223          *
1224          * @see FileBackend::getFileStat()
1225          *
1226          * @param array $params Parameters include:
1227          *   - srcs        : list of source storage paths
1228          *   - latest      : use the latest available data
1229          * @return bool All requests proceeded without I/O errors (since 1.24)
1230          * @since 1.23
1231          */
1232         abstract public function preloadFileStat( array $params );
1233
1234         /**
1235          * Lock the files at the given storage paths in the backend.
1236          * This will either lock all the files or none (on failure).
1237          *
1238          * Callers should consider using getScopedFileLocks() instead.
1239          *
1240          * @param array $paths Storage paths
1241          * @param int $type LockManager::LOCK_* constant
1242          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1243          * @return Status
1244          */
1245         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1246                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1247
1248                 return $this->lockManager->lock( $paths, $type, $timeout );
1249         }
1250
1251         /**
1252          * Unlock the files at the given storage paths in the backend.
1253          *
1254          * @param array $paths Storage paths
1255          * @param int $type LockManager::LOCK_* constant
1256          * @return Status
1257          */
1258         final public function unlockFiles( array $paths, $type ) {
1259                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1260
1261                 return $this->lockManager->unlock( $paths, $type );
1262         }
1263
1264         /**
1265          * Lock the files at the given storage paths in the backend.
1266          * This will either lock all the files or none (on failure).
1267          * On failure, the status object will be updated with errors.
1268          *
1269          * Once the return value goes out scope, the locks will be released and
1270          * the status updated. Unlock fatals will not change the status "OK" value.
1271          *
1272          * @see ScopedLock::factory()
1273          *
1274          * @param array $paths List of storage paths or map of lock types to path lists
1275          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1276          * @param Status $status Status to update on lock/unlock
1277          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1278          * @return ScopedLock|null Returns null on failure
1279          */
1280         final public function getScopedFileLocks( array $paths, $type, Status $status, $timeout = 0 ) {
1281                 if ( $type === 'mixed' ) {
1282                         foreach ( $paths as &$typePaths ) {
1283                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1284                         }
1285                 } else {
1286                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1287                 }
1288
1289                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1290         }
1291
1292         /**
1293          * Get an array of scoped locks needed for a batch of file operations.
1294          *
1295          * Normally, FileBackend::doOperations() handles locking, unless
1296          * the 'nonLocking' param is passed in. This function is useful if you
1297          * want the files to be locked for a broader scope than just when the
1298          * files are changing. For example, if you need to update DB metadata,
1299          * you may want to keep the files locked until finished.
1300          *
1301          * @see FileBackend::doOperations()
1302          *
1303          * @param array $ops List of file operations to FileBackend::doOperations()
1304          * @param Status $status Status to update on lock/unlock
1305          * @return array List of ScopedFileLocks or null values
1306          * @since 1.20
1307          */
1308         abstract public function getScopedLocksForOps( array $ops, Status $status );
1309
1310         /**
1311          * Get the root storage path of this backend.
1312          * All container paths are "subdirectories" of this path.
1313          *
1314          * @return string Storage path
1315          * @since 1.20
1316          */
1317         final public function getRootStoragePath() {
1318                 return "mwstore://{$this->name}";
1319         }
1320
1321         /**
1322          * Get the storage path for the given container for this backend
1323          *
1324          * @param string $container Container name
1325          * @return string Storage path
1326          * @since 1.21
1327          */
1328         final public function getContainerStoragePath( $container ) {
1329                 return $this->getRootStoragePath() . "/{$container}";
1330         }
1331
1332         /**
1333          * Get the file journal object for this backend
1334          *
1335          * @return FileJournal
1336          */
1337         final public function getJournal() {
1338                 return $this->fileJournal;
1339         }
1340
1341         /**
1342          * Check if a given path is a "mwstore://" path.
1343          * This does not do any further validation or any existence checks.
1344          *
1345          * @param string $path
1346          * @return bool
1347          */
1348         final public static function isStoragePath( $path ) {
1349                 return ( strpos( $path, 'mwstore://' ) === 0 );
1350         }
1351
1352         /**
1353          * Split a storage path into a backend name, a container name,
1354          * and a relative file path. The relative path may be the empty string.
1355          * This does not do any path normalization or traversal checks.
1356          *
1357          * @param string $storagePath
1358          * @return array (backend, container, rel object) or (null, null, null)
1359          */
1360         final public static function splitStoragePath( $storagePath ) {
1361                 if ( self::isStoragePath( $storagePath ) ) {
1362                         // Remove the "mwstore://" prefix and split the path
1363                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1364                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1365                                 if ( count( $parts ) == 3 ) {
1366                                         return $parts; // e.g. "backend/container/path"
1367                                 } else {
1368                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
1369                                 }
1370                         }
1371                 }
1372
1373                 return array( null, null, null );
1374         }
1375
1376         /**
1377          * Normalize a storage path by cleaning up directory separators.
1378          * Returns null if the path is not of the format of a valid storage path.
1379          *
1380          * @param string $storagePath
1381          * @return string|null
1382          */
1383         final public static function normalizeStoragePath( $storagePath ) {
1384                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1385                 if ( $relPath !== null ) { // must be for this backend
1386                         $relPath = self::normalizeContainerPath( $relPath );
1387                         if ( $relPath !== null ) {
1388                                 return ( $relPath != '' )
1389                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1390                                         : "mwstore://{$backend}/{$container}";
1391                         }
1392                 }
1393
1394                 return null;
1395         }
1396
1397         /**
1398          * Get the parent storage directory of a storage path.
1399          * This returns a path like "mwstore://backend/container",
1400          * "mwstore://backend/container/...", or null if there is no parent.
1401          *
1402          * @param string $storagePath
1403          * @return string|null
1404          */
1405         final public static function parentStoragePath( $storagePath ) {
1406                 $storagePath = dirname( $storagePath );
1407                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1408
1409                 return ( $rel === null ) ? null : $storagePath;
1410         }
1411
1412         /**
1413          * Get the final extension from a storage or FS path
1414          *
1415          * @param string $path
1416          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1417          * @return string
1418          */
1419         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1420                 $i = strrpos( $path, '.' );
1421                 $ext = $i ? substr( $path, $i + 1 ) : '';
1422
1423                 if ( $case === 'lowercase' ) {
1424                         $ext = strtolower( $ext );
1425                 } elseif ( $case === 'uppercase' ) {
1426                         $ext = strtoupper( $ext );
1427                 }
1428
1429                 return $ext;
1430         }
1431
1432         /**
1433          * Check if a relative path has no directory traversals
1434          *
1435          * @param string $path
1436          * @return bool
1437          * @since 1.20
1438          */
1439         final public static function isPathTraversalFree( $path ) {
1440                 return ( self::normalizeContainerPath( $path ) !== null );
1441         }
1442
1443         /**
1444          * Build a Content-Disposition header value per RFC 6266.
1445          *
1446          * @param string $type One of (attachment, inline)
1447          * @param string $filename Suggested file name (should not contain slashes)
1448          * @throws FileBackendError
1449          * @return string
1450          * @since 1.20
1451          */
1452         final public static function makeContentDisposition( $type, $filename = '' ) {
1453                 $parts = array();
1454
1455                 $type = strtolower( $type );
1456                 if ( !in_array( $type, array( 'inline', 'attachment' ) ) ) {
1457                         throw new FileBackendError( "Invalid Content-Disposition type '$type'." );
1458                 }
1459                 $parts[] = $type;
1460
1461                 if ( strlen( $filename ) ) {
1462                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1463                 }
1464
1465                 return implode( ';', $parts );
1466         }
1467
1468         /**
1469          * Validate and normalize a relative storage path.
1470          * Null is returned if the path involves directory traversal.
1471          * Traversal is insecure for FS backends and broken for others.
1472          *
1473          * This uses the same traversal protection as Title::secureAndSplit().
1474          *
1475          * @param string $path Storage path relative to a container
1476          * @return string|null
1477          */
1478         final protected static function normalizeContainerPath( $path ) {
1479                 // Normalize directory separators
1480                 $path = strtr( $path, '\\', '/' );
1481                 // Collapse any consecutive directory separators
1482                 $path = preg_replace( '![/]{2,}!', '/', $path );
1483                 // Remove any leading directory separator
1484                 $path = ltrim( $path, '/' );
1485                 // Use the same traversal protection as Title::secureAndSplit()
1486                 if ( strpos( $path, '.' ) !== false ) {
1487                         if (
1488                                 $path === '.' ||
1489                                 $path === '..' ||
1490                                 strpos( $path, './' ) === 0 ||
1491                                 strpos( $path, '../' ) === 0 ||
1492                                 strpos( $path, '/./' ) !== false ||
1493                                 strpos( $path, '/../' ) !== false
1494                         ) {
1495                                 return null;
1496                         }
1497                 }
1498
1499                 return $path;
1500         }
1501 }
1502
1503 /**
1504  * Generic file backend exception for checked and unexpected (e.g. config) exceptions
1505  *
1506  * @ingroup FileBackend
1507  * @since 1.23
1508  */
1509 class FileBackendException extends Exception {
1510 }
1511
1512 /**
1513  * File backend exception for checked exceptions (e.g. I/O errors)
1514  *
1515  * @ingroup FileBackend
1516  * @since 1.22
1517  */
1518 class FileBackendError extends FileBackendException {
1519 }