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( [] );
 147                 $this->fileJournal = isset( $config['fileJournal'] )
 148                         ? $config['fileJournal']
 149                         : FileJournal::factory( [ '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          * FSFile/TempFSFile object support was added in 1.27.
 241          *
 242          * a) Create a new file in storage with the contents of a string
 243          * @code
 244          *     array(
 245          *         'op'                  => 'create',
 246          *         'dst'                 => <storage path>,
 247          *         'content'             => <string of new file contents>,
 248          *         'overwrite'           => <boolean>,
 249          *         'overwriteSame'       => <boolean>,
 250          *         'headers'             => <HTTP header name/value map> # since 1.21
 251          *     );
 252          * @endcode
 253          *
 254          * b) Copy a file system file into storage
 255          * @code
 256          *     array(
 257          *         'op'                  => 'store',
 258          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 259          *         'dst'                 => <storage path>,
 260          *         'overwrite'           => <boolean>,
 261          *         'overwriteSame'       => <boolean>,
 262          *         'headers'             => <HTTP header name/value map> # since 1.21
 263          *     )
 264          * @endcode
 265          *
 266          * c) Copy a file within storage
 267          * @code
 268          *     array(
 269          *         'op'                  => 'copy',
 270          *         'src'                 => <storage path>,
 271          *         'dst'                 => <storage path>,
 272          *         'overwrite'           => <boolean>,
 273          *         'overwriteSame'       => <boolean>,
 274          *         'ignoreMissingSource' => <boolean>, # since 1.21
 275          *         'headers'             => <HTTP header name/value map> # since 1.21
 276          *     )
 277          * @endcode
 278          *
 279          * d) Move a file within storage
 280          * @code
 281          *     array(
 282          *         'op'                  => 'move',
 283          *         'src'                 => <storage path>,
 284          *         'dst'                 => <storage path>,
 285          *         'overwrite'           => <boolean>,
 286          *         'overwriteSame'       => <boolean>,
 287          *         'ignoreMissingSource' => <boolean>, # since 1.21
 288          *         'headers'             => <HTTP header name/value map> # since 1.21
 289          *     )
 290          * @endcode
 291          *
 292          * e) Delete a file within storage
 293          * @code
 294          *     array(
 295          *         'op'                  => 'delete',
 296          *         'src'                 => <storage path>,
 297          *         'ignoreMissingSource' => <boolean>
 298          *     )
 299          * @endcode
 300          *
 301          * f) Update metadata for a file within storage
 302          * @code
 303          *     array(
 304          *         'op'                  => 'describe',
 305          *         'src'                 => <storage path>,
 306          *         'headers'             => <HTTP header name/value map>
 307          *     )
 308          * @endcode
 309          *
 310          * g) Do nothing (no-op)
 311          * @code
 312          *     array(
 313          *         'op'                  => 'null',
 314          *     )
 315          * @endcode
 316          *
 317          * Boolean flags for operations (operation-specific):
 318          *   - ignoreMissingSource : The operation will simply succeed and do
 319          *                           nothing if the source file does not exist.
 320          *   - overwrite           : Any destination file will be overwritten.
 321          *   - overwriteSame       : If a file already exists at the destination with the
 322          *                           same contents, then do nothing to the destination file
 323          *                           instead of giving an error. This does not compare headers.
 324          *                           This option is ignored if 'overwrite' is already provided.
 325          *   - headers             : If supplied, the result of merging these headers with any
 326          *                           existing source file headers (replacing conflicting ones)
 327          *                           will be set as the destination file headers. Headers are
 328          *                           deleted if their value is set to the empty string. When a
 329          *                           file has headers they are included in responses to GET and
 330          *                           HEAD requests to the backing store for that file.
 331          *                           Header values should be no larger than 255 bytes, except for
 332          *                           Content-Disposition. The system might ignore or truncate any
 333          *                           headers that are too long to store (exact limits will vary).
 334          *                           Backends that don't support metadata ignore this. (since 1.21)
 335          *
 336          * $opts is an associative of boolean flags, including:
 337          *   - force               : Operation precondition errors no longer trigger an abort.
 338          *                           Any remaining operations are still attempted. Unexpected
 339          *                           failures may still cause remaining operations to be aborted.
 340          *   - nonLocking          : No locks are acquired for the operations.
 341          *                           This can increase performance for non-critical writes.
 342          *                           This has no effect unless the 'force' flag is set.
 343          *   - nonJournaled        : Don't log this operation batch in the file journal.
 344          *                           This limits the ability of recovery scripts.
 345          *   - parallelize         : Try to do operations in parallel when possible.
 346          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 347          *   - preserveCache       : Don't clear the process cache before checking files.
 348          *                           This should only be used if all entries in the process
 349          *                           cache were added after the files were already locked. (since 1.20)
 350          *
 351          * @remarks Remarks on locking:
 352          * File system paths given to operations should refer to files that are
 353          * already locked or otherwise safe from modification from other processes.
 354          * Normally these files will be new temp files, which should be adequate.
 355          *
 356          * @par Return value:
 357          *
 358          * This returns a Status, which contains all warnings and fatals that occurred
 359          * during the operation. The 'failCount', 'successCount', and 'success' members
 360          * will reflect each operation attempted.
 361          *
 362          * The status will be "OK" unless:
 363          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 364          *   - b) significant operation errors occurred and 'force' was not set
 365          *
 366          * @param array $ops List of operations to execute in order
 367          * @param array $opts Batch operation options
 368          * @return Status
 369          */
 370         final public function doOperations( array $ops, array $opts = [] ) {
 371                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 372                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 373                 }
 374                 if ( !count( $ops ) ) {
 375                         return Status::newGood(); // nothing to do
 376                 }
 377
 378                 $ops = $this->resolveFSFileObjects( $ops );
 379                 if ( empty( $opts['force'] ) ) { // sanity
 380                         unset( $opts['nonLocking'] );
 381                 }
 382
 383                 /** @noinspection PhpUnusedLocalVariableInspection */
 384                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 385
 386                 return $this->doOperationsInternal( $ops, $opts );
 387         }
 388
 389         /**
 390          * @see FileBackend::doOperations()
 391          * @param array $ops
 392          * @param array $opts
 393          */
 394         abstract protected function doOperationsInternal( array $ops, array $opts );
 395
 396         /**
 397          * Same as doOperations() except it takes a single operation.
 398          * If you are doing a batch of operations that should either
 399          * all succeed or all fail, then use that function instead.
 400          *
 401          * @see FileBackend::doOperations()
 402          *
 403          * @param array $op Operation
 404          * @param array $opts Operation options
 405          * @return Status
 406          */
 407         final public function doOperation( array $op, array $opts = [] ) {
 408                 return $this->doOperations( [ $op ], $opts );
 409         }
 410
 411         /**
 412          * Performs a single create operation.
 413          * This sets $params['op'] to 'create' and passes it to doOperation().
 414          *
 415          * @see FileBackend::doOperation()
 416          *
 417          * @param array $params Operation parameters
 418          * @param array $opts Operation options
 419          * @return Status
 420          */
 421         final public function create( array $params, array $opts = [] ) {
 422                 return $this->doOperation( [ 'op' => 'create' ] + $params, $opts );
 423         }
 424
 425         /**
 426          * Performs a single store operation.
 427          * This sets $params['op'] to 'store' and passes it to doOperation().
 428          *
 429          * @see FileBackend::doOperation()
 430          *
 431          * @param array $params Operation parameters
 432          * @param array $opts Operation options
 433          * @return Status
 434          */
 435         final public function store( array $params, array $opts = [] ) {
 436                 return $this->doOperation( [ 'op' => 'store' ] + $params, $opts );
 437         }
 438
 439         /**
 440          * Performs a single copy operation.
 441          * This sets $params['op'] to 'copy' and passes it to doOperation().
 442          *
 443          * @see FileBackend::doOperation()
 444          *
 445          * @param array $params Operation parameters
 446          * @param array $opts Operation options
 447          * @return Status
 448          */
 449         final public function copy( array $params, array $opts = [] ) {
 450                 return $this->doOperation( [ 'op' => 'copy' ] + $params, $opts );
 451         }
 452
 453         /**
 454          * Performs a single move operation.
 455          * This sets $params['op'] to 'move' and passes it to doOperation().
 456          *
 457          * @see FileBackend::doOperation()
 458          *
 459          * @param array $params Operation parameters
 460          * @param array $opts Operation options
 461          * @return Status
 462          */
 463         final public function move( array $params, array $opts = [] ) {
 464                 return $this->doOperation( [ 'op' => 'move' ] + $params, $opts );
 465         }
 466
 467         /**
 468          * Performs a single delete operation.
 469          * This sets $params['op'] to 'delete' and passes it to doOperation().
 470          *
 471          * @see FileBackend::doOperation()
 472          *
 473          * @param array $params Operation parameters
 474          * @param array $opts Operation options
 475          * @return Status
 476          */
 477         final public function delete( array $params, array $opts = [] ) {
 478                 return $this->doOperation( [ 'op' => 'delete' ] + $params, $opts );
 479         }
 480
 481         /**
 482          * Performs a single describe operation.
 483          * This sets $params['op'] to 'describe' and passes it to doOperation().
 484          *
 485          * @see FileBackend::doOperation()
 486          *
 487          * @param array $params Operation parameters
 488          * @param array $opts Operation options
 489          * @return Status
 490          * @since 1.21
 491          */
 492         final public function describe( array $params, array $opts = [] ) {
 493                 return $this->doOperation( [ 'op' => 'describe' ] + $params, $opts );
 494         }
 495
 496         /**
 497          * Perform a set of independent file operations on some files.
 498          *
 499          * This does no locking, nor journaling, and possibly no stat calls.
 500          * Any destination files that already exist will be overwritten.
 501          * This should *only* be used on non-original files, like cache files.
 502          *
 503          * Supported operations and their parameters:
 504          *  - create
 505          *  - store
 506          *  - copy
 507          *  - move
 508          *  - delete
 509          *  - describe (since 1.21)
 510          *  - null
 511          *
 512          * FSFile/TempFSFile object support was added in 1.27.
 513          *
 514          * a) Create a new file in storage with the contents of a string
 515          * @code
 516          *     array(
 517          *         'op'                  => 'create',
 518          *         'dst'                 => <storage path>,
 519          *         'content'             => <string of new file contents>,
 520          *         'headers'             => <HTTP header name/value map> # since 1.21
 521          *     )
 522          * @endcode
 523          *
 524          * b) Copy a file system file into storage
 525          * @code
 526          *     array(
 527          *         'op'                  => 'store',
 528          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 529          *         'dst'                 => <storage path>,
 530          *         'headers'             => <HTTP header name/value map> # since 1.21
 531          *     )
 532          * @endcode
 533          *
 534          * c) Copy a file within storage
 535          * @code
 536          *     array(
 537          *         'op'                  => 'copy',
 538          *         'src'                 => <storage path>,
 539          *         'dst'                 => <storage path>,
 540          *         'ignoreMissingSource' => <boolean>, # since 1.21
 541          *         'headers'             => <HTTP header name/value map> # since 1.21
 542          *     )
 543          * @endcode
 544          *
 545          * d) Move a file within storage
 546          * @code
 547          *     array(
 548          *         'op'                  => 'move',
 549          *         'src'                 => <storage path>,
 550          *         'dst'                 => <storage path>,
 551          *         'ignoreMissingSource' => <boolean>, # since 1.21
 552          *         'headers'             => <HTTP header name/value map> # since 1.21
 553          *     )
 554          * @endcode
 555          *
 556          * e) Delete a file within storage
 557          * @code
 558          *     array(
 559          *         'op'                  => 'delete',
 560          *         'src'                 => <storage path>,
 561          *         'ignoreMissingSource' => <boolean>
 562          *     )
 563          * @endcode
 564          *
 565          * f) Update metadata for a file within storage
 566          * @code
 567          *     array(
 568          *         'op'                  => 'describe',
 569          *         'src'                 => <storage path>,
 570          *         'headers'             => <HTTP header name/value map>
 571          *     )
 572          * @endcode
 573          *
 574          * g) Do nothing (no-op)
 575          * @code
 576          *     array(
 577          *         'op'                  => 'null',
 578          *     )
 579          * @endcode
 580          *
 581          * @par Boolean flags for operations (operation-specific):
 582          *   - ignoreMissingSource : The operation will simply succeed and do
 583          *                           nothing if the source file does not exist.
 584          *   - headers             : If supplied with a header name/value map, the backend will
 585          *                           reply with these headers when GETs/HEADs of the destination
 586          *                           file are made. Header values should be smaller than 256 bytes.
 587          *                           Content-Disposition headers can be longer, though the system
 588          *                           might ignore or truncate ones that are too long to store.
 589          *                           Existing headers will remain, but these will replace any
 590          *                           conflicting previous headers, and headers will be removed
 591          *                           if they are set to an empty string.
 592          *                           Backends that don't support metadata ignore this. (since 1.21)
 593          *
 594          * $opts is an associative of boolean flags, including:
 595          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 596          *
 597          * @par Return value:
 598          * This returns a Status, which contains all warnings and fatals that occurred
 599          * during the operation. The 'failCount', 'successCount', and 'success' members
 600          * will reflect each operation attempted for the given files. The status will be
 601          * considered "OK" as long as no fatal errors occurred.
 602          *
 603          * @param array $ops Set of operations to execute
 604          * @param array $opts Batch operation options
 605          * @return Status
 606          * @since 1.20
 607          */
 608         final public function doQuickOperations( array $ops, array $opts = [] ) {
 609                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 610                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 611                 }
 612                 if ( !count( $ops ) ) {
 613                         return Status::newGood(); // nothing to do
 614                 }
 615
 616                 $ops = $this->resolveFSFileObjects( $ops );
 617                 foreach ( $ops as &$op ) {
 618                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 619                 }
 620
 621                 /** @noinspection PhpUnusedLocalVariableInspection */
 622                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 623
 624                 return $this->doQuickOperationsInternal( $ops );
 625         }
 626
 627         /**
 628          * @see FileBackend::doQuickOperations()
 629          * @param array $ops
 630          * @since 1.20
 631          */
 632         abstract protected function doQuickOperationsInternal( array $ops );
 633
 634         /**
 635          * Same as doQuickOperations() except it takes a single operation.
 636          * If you are doing a batch of operations, then use that function instead.
 637          *
 638          * @see FileBackend::doQuickOperations()
 639          *
 640          * @param array $op Operation
 641          * @return Status
 642          * @since 1.20
 643          */
 644         final public function doQuickOperation( array $op ) {
 645                 return $this->doQuickOperations( [ $op ] );
 646         }
 647
 648         /**
 649          * Performs a single quick create operation.
 650          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 651          *
 652          * @see FileBackend::doQuickOperation()
 653          *
 654          * @param array $params Operation parameters
 655          * @return Status
 656          * @since 1.20
 657          */
 658         final public function quickCreate( array $params ) {
 659                 return $this->doQuickOperation( [ 'op' => 'create' ] + $params );
 660         }
 661
 662         /**
 663          * Performs a single quick store operation.
 664          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 665          *
 666          * @see FileBackend::doQuickOperation()
 667          *
 668          * @param array $params Operation parameters
 669          * @return Status
 670          * @since 1.20
 671          */
 672         final public function quickStore( array $params ) {
 673                 return $this->doQuickOperation( [ 'op' => 'store' ] + $params );
 674         }
 675
 676         /**
 677          * Performs a single quick copy operation.
 678          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 679          *
 680          * @see FileBackend::doQuickOperation()
 681          *
 682          * @param array $params Operation parameters
 683          * @return Status
 684          * @since 1.20
 685          */
 686         final public function quickCopy( array $params ) {
 687                 return $this->doQuickOperation( [ 'op' => 'copy' ] + $params );
 688         }
 689
 690         /**
 691          * Performs a single quick move operation.
 692          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 693          *
 694          * @see FileBackend::doQuickOperation()
 695          *
 696          * @param array $params Operation parameters
 697          * @return Status
 698          * @since 1.20
 699          */
 700         final public function quickMove( array $params ) {
 701                 return $this->doQuickOperation( [ 'op' => 'move' ] + $params );
 702         }
 703
 704         /**
 705          * Performs a single quick delete operation.
 706          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 707          *
 708          * @see FileBackend::doQuickOperation()
 709          *
 710          * @param array $params Operation parameters
 711          * @return Status
 712          * @since 1.20
 713          */
 714         final public function quickDelete( array $params ) {
 715                 return $this->doQuickOperation( [ 'op' => 'delete' ] + $params );
 716         }
 717
 718         /**
 719          * Performs a single quick describe operation.
 720          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 721          *
 722          * @see FileBackend::doQuickOperation()
 723          *
 724          * @param array $params Operation parameters
 725          * @return Status
 726          * @since 1.21
 727          */
 728         final public function quickDescribe( array $params ) {
 729                 return $this->doQuickOperation( [ 'op' => 'describe' ] + $params );
 730         }
 731
 732         /**
 733          * Concatenate a list of storage files into a single file system file.
 734          * The target path should refer to a file that is already locked or
 735          * otherwise safe from modification from other processes. Normally,
 736          * the file will be a new temp file, which should be adequate.
 737          *
 738          * @param array $params Operation parameters, include:
 739          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 740          *   - dst         : file system path to 0-byte temp file
 741          *   - parallelize : try to do operations in parallel when possible
 742          * @return Status
 743          */
 744         abstract public function concatenate( array $params );
 745
 746         /**
 747          * Prepare a storage directory for usage.
 748          * This will create any required containers and parent directories.
 749          * Backends using key/value stores only need to create the container.
 750          *
 751          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 752          * except they are only applied *if* the directory/container had to be created.
 753          * These flags should always be set for directories that have private files.
 754          * However, setting them is not guaranteed to actually do anything.
 755          * Additional server configuration may be needed to achieve the desired effect.
 756          *
 757          * @param array $params Parameters include:
 758          *   - dir            : storage directory
 759          *   - noAccess       : try to deny file access (since 1.20)
 760          *   - noListing      : try to deny file listing (since 1.20)
 761          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 762          * @return Status
 763          */
 764         final public function prepare( array $params ) {
 765                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 766                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 767                 }
 768                 /** @noinspection PhpUnusedLocalVariableInspection */
 769                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 770                 return $this->doPrepare( $params );
 771         }
 772
 773         /**
 774          * @see FileBackend::prepare()
 775          * @param array $params
 776          */
 777         abstract protected function doPrepare( array $params );
 778
 779         /**
 780          * Take measures to block web access to a storage directory and
 781          * the container it belongs to. FS backends might add .htaccess
 782          * files whereas key/value store backends might revoke container
 783          * access to the storage user representing end-users in web requests.
 784          *
 785          * This is not guaranteed to actually make files or listings publically hidden.
 786          * Additional server configuration may be needed to achieve the desired effect.
 787          *
 788          * @param array $params Parameters include:
 789          *   - dir            : storage directory
 790          *   - noAccess       : try to deny file access
 791          *   - noListing      : try to deny file listing
 792          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 793          * @return Status
 794          */
 795         final public function secure( array $params ) {
 796                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 797                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 798                 }
 799                 /** @noinspection PhpUnusedLocalVariableInspection */
 800                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 801                 return $this->doSecure( $params );
 802         }
 803
 804         /**
 805          * @see FileBackend::secure()
 806          * @param array $params
 807          */
 808         abstract protected function doSecure( array $params );
 809
 810         /**
 811          * Remove measures to block web access to a storage directory and
 812          * the container it belongs to. FS backends might remove .htaccess
 813          * files whereas key/value store backends might grant container
 814          * access to the storage user representing end-users in web requests.
 815          * This essentially can undo the result of secure() calls.
 816          *
 817          * This is not guaranteed to actually make files or listings publically viewable.
 818          * Additional server configuration may be needed to achieve the desired effect.
 819          *
 820          * @param array $params Parameters include:
 821          *   - dir            : storage directory
 822          *   - access         : try to allow file access
 823          *   - listing        : try to allow file listing
 824          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 825          * @return Status
 826          * @since 1.20
 827          */
 828         final public function publish( array $params ) {
 829                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 830                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 831                 }
 832                 /** @noinspection PhpUnusedLocalVariableInspection */
 833                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 834                 return $this->doPublish( $params );
 835         }
 836
 837         /**
 838          * @see FileBackend::publish()
 839          * @param array $params
 840          */
 841         abstract protected function doPublish( array $params );
 842
 843         /**
 844          * Delete a storage directory if it is empty.
 845          * Backends using key/value stores may do nothing unless the directory
 846          * is that of an empty container, in which case it will be deleted.
 847          *
 848          * @param array $params Parameters include:
 849          *   - dir            : storage directory
 850          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 851          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 852          * @return Status
 853          */
 854         final public function clean( array $params ) {
 855                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 856                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 857                 }
 858                 /** @noinspection PhpUnusedLocalVariableInspection */
 859                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 860                 return $this->doClean( $params );
 861         }
 862
 863         /**
 864          * @see FileBackend::clean()
 865          * @param array $params
 866          */
 867         abstract protected function doClean( array $params );
 868
 869         /**
 870          * Enter file operation scope.
 871          * This just makes PHP ignore user aborts/disconnects until the return
 872          * value leaves scope. This returns null and does nothing in CLI mode.
 873          *
 874          * @return ScopedCallback|null
 875          */
 876         final protected function getScopedPHPBehaviorForOps() {
 877                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 878                         $old = ignore_user_abort( true ); // avoid half-finished operations
 879                         return new ScopedCallback( function () use ( $old ) {
 880                                 ignore_user_abort( $old );
 881                         } );
 882                 }
 883
 884                 return null;
 885         }
 886
 887         /**
 888          * Check if a file exists at a storage path in the backend.
 889          * This returns false if only a directory exists at the path.
 890          *
 891          * @param array $params Parameters include:
 892          *   - src    : source storage path
 893          *   - latest : use the latest available data
 894          * @return bool|null Returns null on failure
 895          */
 896         abstract public function fileExists( array $params );
 897
 898         /**
 899          * Get the last-modified timestamp of the file at a storage path.
 900          *
 901          * @param array $params Parameters include:
 902          *   - src    : source storage path
 903          *   - latest : use the latest available data
 904          * @return string|bool TS_MW timestamp or false on failure
 905          */
 906         abstract public function getFileTimestamp( array $params );
 907
 908         /**
 909          * Get the contents of a file at a storage path in the backend.
 910          * This should be avoided for potentially large files.
 911          *
 912          * @param array $params Parameters include:
 913          *   - src    : source storage path
 914          *   - latest : use the latest available data
 915          * @return string|bool Returns false on failure
 916          */
 917         final public function getFileContents( array $params ) {
 918                 $contents = $this->getFileContentsMulti(
 919                         [ 'srcs' => [ $params['src'] ] ] + $params );
 920
 921                 return $contents[$params['src']];
 922         }
 923
 924         /**
 925          * Like getFileContents() except it takes an array of storage paths
 926          * and returns a map of storage paths to strings (or null on failure).
 927          * The map keys (paths) are in the same order as the provided list of paths.
 928          *
 929          * @see FileBackend::getFileContents()
 930          *
 931          * @param array $params Parameters include:
 932          *   - srcs        : list of source storage paths
 933          *   - latest      : use the latest available data
 934          *   - parallelize : try to do operations in parallel when possible
 935          * @return array Map of (path name => string or false on failure)
 936          * @since 1.20
 937          */
 938         abstract public function getFileContentsMulti( array $params );
 939
 940         /**
 941          * Get metadata about a file at a storage path in the backend.
 942          * If the file does not exist, then this returns false.
 943          * Otherwise, the result is an associative array that includes:
 944          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 945          *   - metadata : map of file metadata (name => value)
 946          * Metadata keys and headers names will be returned in all lower-case.
 947          * Additional values may be included for internal use only.
 948          *
 949          * Use FileBackend::hasFeatures() to check how well this is supported.
 950          *
 951          * @param array $params
 952          * $params include:
 953          *   - src    : source storage path
 954          *   - latest : use the latest available data
 955          * @return array|bool Returns false on failure
 956          * @since 1.23
 957          */
 958         abstract public function getFileXAttributes( array $params );
 959
 960         /**
 961          * Get the size (bytes) of a file at a storage path in the backend.
 962          *
 963          * @param array $params Parameters include:
 964          *   - src    : source storage path
 965          *   - latest : use the latest available data
 966          * @return int|bool Returns false on failure
 967          */
 968         abstract public function getFileSize( array $params );
 969
 970         /**
 971          * Get quick information about a file at a storage path in the backend.
 972          * If the file does not exist, then this returns false.
 973          * Otherwise, the result is an associative array that includes:
 974          *   - mtime  : the last-modified timestamp (TS_MW)
 975          *   - size   : the file size (bytes)
 976          * Additional values may be included for internal use only.
 977          *
 978          * @param array $params Parameters include:
 979          *   - src    : source storage path
 980          *   - latest : use the latest available data
 981          * @return array|bool|null Returns null on failure
 982          */
 983         abstract public function getFileStat( array $params );
 984
 985         /**
 986          * Get a SHA-1 hash of the file at a storage path in the backend.
 987          *
 988          * @param array $params Parameters include:
 989          *   - src    : source storage path
 990          *   - latest : use the latest available data
 991          * @return string|bool Hash string or false on failure
 992          */
 993         abstract public function getFileSha1Base36( array $params );
 994
 995         /**
 996          * Get the properties of the file at a storage path in the backend.
 997          * This gives the result of FSFile::getProps() on a local copy of the file.
 998          *
 999          * @param array $params Parameters include:
1000          *   - src    : source storage path
1001          *   - latest : use the latest available data
1002          * @return array Returns FSFile::placeholderProps() on failure
1003          */
1004         abstract public function getFileProps( array $params );
1005
1006         /**
1007          * Stream the file at a storage path in the backend.
1008          *
1009          * If the file does not exists, an HTTP 404 error will be given.
1010          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
1011          * will be sent if streaming began, while none will be sent otherwise.
1012          * Implementations should flush the output buffer before sending data.
1013          *
1014          * @param array $params Parameters include:
1015          *   - src      : source storage path
1016          *   - headers  : list of additional HTTP headers to send if the file exists
1017          *   - options  : HTTP request header map with lower case keys (since 1.28). Supports:
1018          *                range             : format is "bytes=(\d*-\d*)"
1019          *                if-modified-since : format is an HTTP date
1020          *   - headless : only include the body (and headers from "headers") (since 1.28)
1021          *   - latest   : use the latest available data
1022          *   - allowOB  : preserve any output buffers (since 1.28)
1023          * @return Status
1024          */
1025         abstract public function streamFile( array $params );
1026
1027         /**
1028          * Returns a file system file, identical to the file at a storage path.
1029          * The file returned is either:
1030          *   - a) A local copy of the file at a storage path in the backend.
1031          *        The temporary copy will have the same extension as the source.
1032          *   - b) An original of the file at a storage path in the backend.
1033          * Temporary files may be purged when the file object falls out of scope.
1034          *
1035          * Write operations should *never* be done on this file as some backends
1036          * may do internal tracking or may be instances of FileBackendMultiWrite.
1037          * In that later case, there are copies of the file that must stay in sync.
1038          * Additionally, further calls to this function may return the same file.
1039          *
1040          * @param array $params Parameters include:
1041          *   - src    : source storage path
1042          *   - latest : use the latest available data
1043          * @return FSFile|null Returns null on failure
1044          */
1045         final public function getLocalReference( array $params ) {
1046                 $fsFiles = $this->getLocalReferenceMulti(
1047                         [ 'srcs' => [ $params['src'] ] ] + $params );
1048
1049                 return $fsFiles[$params['src']];
1050         }
1051
1052         /**
1053          * Like getLocalReference() except it takes an array of storage paths
1054          * and returns a map of storage paths to FSFile objects (or null on failure).
1055          * The map keys (paths) are in the same order as the provided list of paths.
1056          *
1057          * @see FileBackend::getLocalReference()
1058          *
1059          * @param array $params Parameters include:
1060          *   - srcs        : list of source storage paths
1061          *   - latest      : use the latest available data
1062          *   - parallelize : try to do operations in parallel when possible
1063          * @return array Map of (path name => FSFile or null on failure)
1064          * @since 1.20
1065          */
1066         abstract public function getLocalReferenceMulti( array $params );
1067
1068         /**
1069          * Get a local copy on disk of the file at a storage path in the backend.
1070          * The temporary copy will have the same file extension as the source.
1071          * Temporary files may be purged when the file object falls out of scope.
1072          *
1073          * @param array $params Parameters include:
1074          *   - src    : source storage path
1075          *   - latest : use the latest available data
1076          * @return TempFSFile|null Returns null on failure
1077          */
1078         final public function getLocalCopy( array $params ) {
1079                 $tmpFiles = $this->getLocalCopyMulti(
1080                         [ 'srcs' => [ $params['src'] ] ] + $params );
1081
1082                 return $tmpFiles[$params['src']];
1083         }
1084
1085         /**
1086          * Like getLocalCopy() except it takes an array of storage paths and
1087          * returns a map of storage paths to TempFSFile objects (or null on failure).
1088          * The map keys (paths) are in the same order as the provided list of paths.
1089          *
1090          * @see FileBackend::getLocalCopy()
1091          *
1092          * @param array $params Parameters include:
1093          *   - srcs        : list of source storage paths
1094          *   - latest      : use the latest available data
1095          *   - parallelize : try to do operations in parallel when possible
1096          * @return array Map of (path name => TempFSFile or null on failure)
1097          * @since 1.20
1098          */
1099         abstract public function getLocalCopyMulti( array $params );
1100
1101         /**
1102          * Return an HTTP URL to a given file that requires no authentication to use.
1103          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1104          * This will return null if the backend cannot make an HTTP URL for the file.
1105          *
1106          * This is useful for key/value stores when using scripts that seek around
1107          * large files and those scripts (and the backend) support HTTP Range headers.
1108          * Otherwise, one would need to use getLocalReference(), which involves loading
1109          * the entire file on to local disk.
1110          *
1111          * @param array $params Parameters include:
1112          *   - src : source storage path
1113          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1114          * @return string|null
1115          * @since 1.21
1116          */
1117         abstract public function getFileHttpUrl( array $params );
1118
1119         /**
1120          * Check if a directory exists at a given storage path.
1121          * Backends using key/value stores will check if the path is a
1122          * virtual directory, meaning there are files under the given directory.
1123          *
1124          * Storage backends with eventual consistency might return stale data.
1125          *
1126          * @param array $params Parameters include:
1127          *   - dir : storage directory
1128          * @return bool|null Returns null on failure
1129          * @since 1.20
1130          */
1131         abstract public function directoryExists( array $params );
1132
1133         /**
1134          * Get an iterator to list *all* directories under a storage directory.
1135          * If the directory is of the form "mwstore://backend/container",
1136          * then all directories in the container will be listed.
1137          * If the directory is of form "mwstore://backend/container/dir",
1138          * then all directories directly under that directory will be listed.
1139          * Results will be storage directories relative to the given directory.
1140          *
1141          * Storage backends with eventual consistency might return stale data.
1142          *
1143          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1144          *
1145          * @param array $params Parameters include:
1146          *   - dir     : storage directory
1147          *   - topOnly : only return direct child dirs of the directory
1148          * @return Traversable|array|null Returns null on failure
1149          * @since 1.20
1150          */
1151         abstract public function getDirectoryList( array $params );
1152
1153         /**
1154          * Same as FileBackend::getDirectoryList() except only lists
1155          * directories that are immediately under the given directory.
1156          *
1157          * Storage backends with eventual consistency might return stale data.
1158          *
1159          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1160          *
1161          * @param array $params Parameters include:
1162          *   - dir : storage directory
1163          * @return Traversable|array|null Returns null on failure
1164          * @since 1.20
1165          */
1166         final public function getTopDirectoryList( array $params ) {
1167                 return $this->getDirectoryList( [ 'topOnly' => true ] + $params );
1168         }
1169
1170         /**
1171          * Get an iterator to list *all* stored files under a storage directory.
1172          * If the directory is of the form "mwstore://backend/container",
1173          * then all files in the container will be listed.
1174          * If the directory is of form "mwstore://backend/container/dir",
1175          * then all files under that directory will be listed.
1176          * Results will be storage paths relative to the given directory.
1177          *
1178          * Storage backends with eventual consistency might return stale data.
1179          *
1180          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1181          *
1182          * @param array $params Parameters include:
1183          *   - dir        : storage directory
1184          *   - topOnly    : only return direct child files of the directory (since 1.20)
1185          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1186          * @return Traversable|array|null Returns null on failure
1187          */
1188         abstract public function getFileList( array $params );
1189
1190         /**
1191          * Same as FileBackend::getFileList() except only lists
1192          * files that are immediately under the given directory.
1193          *
1194          * Storage backends with eventual consistency might return stale data.
1195          *
1196          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1197          *
1198          * @param array $params Parameters include:
1199          *   - dir        : storage directory
1200          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1201          * @return Traversable|array|null Returns null on failure
1202          * @since 1.20
1203          */
1204         final public function getTopFileList( array $params ) {
1205                 return $this->getFileList( [ 'topOnly' => true ] + $params );
1206         }
1207
1208         /**
1209          * Preload persistent file stat cache and property cache into in-process cache.
1210          * This should be used when stat calls will be made on a known list of a many files.
1211          *
1212          * @see FileBackend::getFileStat()
1213          *
1214          * @param array $paths Storage paths
1215          */
1216         abstract public function preloadCache( array $paths );
1217
1218         /**
1219          * Invalidate any in-process file stat and property cache.
1220          * If $paths is given, then only the cache for those files will be cleared.
1221          *
1222          * @see FileBackend::getFileStat()
1223          *
1224          * @param array $paths Storage paths (optional)
1225          */
1226         abstract public function clearCache( array $paths = null );
1227
1228         /**
1229          * Preload file stat information (concurrently if possible) into in-process cache.
1230          *
1231          * This should be used when stat calls will be made on a known list of a many files.
1232          * This does not make use of the persistent file stat cache.
1233          *
1234          * @see FileBackend::getFileStat()
1235          *
1236          * @param array $params Parameters include:
1237          *   - srcs        : list of source storage paths
1238          *   - latest      : use the latest available data
1239          * @return bool All requests proceeded without I/O errors (since 1.24)
1240          * @since 1.23
1241          */
1242         abstract public function preloadFileStat( array $params );
1243
1244         /**
1245          * Lock the files at the given storage paths in the backend.
1246          * This will either lock all the files or none (on failure).
1247          *
1248          * Callers should consider using getScopedFileLocks() instead.
1249          *
1250          * @param array $paths Storage paths
1251          * @param int $type LockManager::LOCK_* constant
1252          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1253          * @return Status
1254          */
1255         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1256                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1257
1258                 return $this->lockManager->lock( $paths, $type, $timeout );
1259         }
1260
1261         /**
1262          * Unlock the files at the given storage paths in the backend.
1263          *
1264          * @param array $paths Storage paths
1265          * @param int $type LockManager::LOCK_* constant
1266          * @return Status
1267          */
1268         final public function unlockFiles( array $paths, $type ) {
1269                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1270
1271                 return $this->lockManager->unlock( $paths, $type );
1272         }
1273
1274         /**
1275          * Lock the files at the given storage paths in the backend.
1276          * This will either lock all the files or none (on failure).
1277          * On failure, the status object will be updated with errors.
1278          *
1279          * Once the return value goes out scope, the locks will be released and
1280          * the status updated. Unlock fatals will not change the status "OK" value.
1281          *
1282          * @see ScopedLock::factory()
1283          *
1284          * @param array $paths List of storage paths or map of lock types to path lists
1285          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1286          * @param Status $status Status to update on lock/unlock
1287          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1288          * @return ScopedLock|null Returns null on failure
1289          */
1290         final public function getScopedFileLocks( array $paths, $type, Status $status, $timeout = 0 ) {
1291                 if ( $type === 'mixed' ) {
1292                         foreach ( $paths as &$typePaths ) {
1293                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1294                         }
1295                 } else {
1296                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1297                 }
1298
1299                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1300         }
1301
1302         /**
1303          * Get an array of scoped locks needed for a batch of file operations.
1304          *
1305          * Normally, FileBackend::doOperations() handles locking, unless
1306          * the 'nonLocking' param is passed in. This function is useful if you
1307          * want the files to be locked for a broader scope than just when the
1308          * files are changing. For example, if you need to update DB metadata,
1309          * you may want to keep the files locked until finished.
1310          *
1311          * @see FileBackend::doOperations()
1312          *
1313          * @param array $ops List of file operations to FileBackend::doOperations()
1314          * @param Status $status Status to update on lock/unlock
1315          * @return ScopedLock|null
1316          * @since 1.20
1317          */
1318         abstract public function getScopedLocksForOps( array $ops, Status $status );
1319
1320         /**
1321          * Get the root storage path of this backend.
1322          * All container paths are "subdirectories" of this path.
1323          *
1324          * @return string Storage path
1325          * @since 1.20
1326          */
1327         final public function getRootStoragePath() {
1328                 return "mwstore://{$this->name}";
1329         }
1330
1331         /**
1332          * Get the storage path for the given container for this backend
1333          *
1334          * @param string $container Container name
1335          * @return string Storage path
1336          * @since 1.21
1337          */
1338         final public function getContainerStoragePath( $container ) {
1339                 return $this->getRootStoragePath() . "/{$container}";
1340         }
1341
1342         /**
1343          * Get the file journal object for this backend
1344          *
1345          * @return FileJournal
1346          */
1347         final public function getJournal() {
1348                 return $this->fileJournal;
1349         }
1350
1351         /**
1352          * Convert FSFile 'src' paths to string paths (with an 'srcRef' field set to the FSFile)
1353          *
1354          * The 'srcRef' field keeps any TempFSFile objects in scope for the backend to have it
1355          * around as long it needs (which may vary greatly depending on configuration)
1356          *
1357          * @param array $ops File operation batch for FileBaclend::doOperations()
1358          * @return array File operation batch
1359          */
1360         protected function resolveFSFileObjects( array $ops ) {
1361                 foreach ( $ops as &$op ) {
1362                         $src = isset( $op['src'] ) ? $op['src'] : null;
1363                         if ( $src instanceof FSFile ) {
1364                                 $op['srcRef'] = $src;
1365                                 $op['src'] = $src->getPath();
1366                         }
1367                 }
1368                 unset( $op );
1369
1370                 return $ops;
1371         }
1372
1373         /**
1374          * Check if a given path is a "mwstore://" path.
1375          * This does not do any further validation or any existence checks.
1376          *
1377          * @param string $path
1378          * @return bool
1379          */
1380         final public static function isStoragePath( $path ) {
1381                 return ( strpos( $path, 'mwstore://' ) === 0 );
1382         }
1383
1384         /**
1385          * Split a storage path into a backend name, a container name,
1386          * and a relative file path. The relative path may be the empty string.
1387          * This does not do any path normalization or traversal checks.
1388          *
1389          * @param string $storagePath
1390          * @return array (backend, container, rel object) or (null, null, null)
1391          */
1392         final public static function splitStoragePath( $storagePath ) {
1393                 if ( self::isStoragePath( $storagePath ) ) {
1394                         // Remove the "mwstore://" prefix and split the path
1395                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1396                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1397                                 if ( count( $parts ) == 3 ) {
1398                                         return $parts; // e.g. "backend/container/path"
1399                                 } else {
1400                                         return [ $parts[0], $parts[1], '' ]; // e.g. "backend/container"
1401                                 }
1402                         }
1403                 }
1404
1405                 return [ null, null, null ];
1406         }
1407
1408         /**
1409          * Normalize a storage path by cleaning up directory separators.
1410          * Returns null if the path is not of the format of a valid storage path.
1411          *
1412          * @param string $storagePath
1413          * @return string|null
1414          */
1415         final public static function normalizeStoragePath( $storagePath ) {
1416                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1417                 if ( $relPath !== null ) { // must be for this backend
1418                         $relPath = self::normalizeContainerPath( $relPath );
1419                         if ( $relPath !== null ) {
1420                                 return ( $relPath != '' )
1421                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1422                                         : "mwstore://{$backend}/{$container}";
1423                         }
1424                 }
1425
1426                 return null;
1427         }
1428
1429         /**
1430          * Get the parent storage directory of a storage path.
1431          * This returns a path like "mwstore://backend/container",
1432          * "mwstore://backend/container/...", or null if there is no parent.
1433          *
1434          * @param string $storagePath
1435          * @return string|null
1436          */
1437         final public static function parentStoragePath( $storagePath ) {
1438                 $storagePath = dirname( $storagePath );
1439                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1440
1441                 return ( $rel === null ) ? null : $storagePath;
1442         }
1443
1444         /**
1445          * Get the final extension from a storage or FS path
1446          *
1447          * @param string $path
1448          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1449          * @return string
1450          */
1451         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1452                 $i = strrpos( $path, '.' );
1453                 $ext = $i ? substr( $path, $i + 1 ) : '';
1454
1455                 if ( $case === 'lowercase' ) {
1456                         $ext = strtolower( $ext );
1457                 } elseif ( $case === 'uppercase' ) {
1458                         $ext = strtoupper( $ext );
1459                 }
1460
1461                 return $ext;
1462         }
1463
1464         /**
1465          * Check if a relative path has no directory traversals
1466          *
1467          * @param string $path
1468          * @return bool
1469          * @since 1.20
1470          */
1471         final public static function isPathTraversalFree( $path ) {
1472                 return ( self::normalizeContainerPath( $path ) !== null );
1473         }
1474
1475         /**
1476          * Build a Content-Disposition header value per RFC 6266.
1477          *
1478          * @param string $type One of (attachment, inline)
1479          * @param string $filename Suggested file name (should not contain slashes)
1480          * @throws FileBackendError
1481          * @return string
1482          * @since 1.20
1483          */
1484         final public static function makeContentDisposition( $type, $filename = '' ) {
1485                 $parts = [];
1486
1487                 $type = strtolower( $type );
1488                 if ( !in_array( $type, [ 'inline', 'attachment' ] ) ) {
1489                         throw new FileBackendError( "Invalid Content-Disposition type '$type'." );
1490                 }
1491                 $parts[] = $type;
1492
1493                 if ( strlen( $filename ) ) {
1494                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1495                 }
1496
1497                 return implode( ';', $parts );
1498         }
1499
1500         /**
1501          * Validate and normalize a relative storage path.
1502          * Null is returned if the path involves directory traversal.
1503          * Traversal is insecure for FS backends and broken for others.
1504          *
1505          * This uses the same traversal protection as Title::secureAndSplit().
1506          *
1507          * @param string $path Storage path relative to a container
1508          * @return string|null
1509          */
1510         final protected static function normalizeContainerPath( $path ) {
1511                 // Normalize directory separators
1512                 $path = strtr( $path, '\\', '/' );
1513                 // Collapse any consecutive directory separators
1514                 $path = preg_replace( '![/]{2,}!', '/', $path );
1515                 // Remove any leading directory separator
1516                 $path = ltrim( $path, '/' );
1517                 // Use the same traversal protection as Title::secureAndSplit()
1518                 if ( strpos( $path, '.' ) !== false ) {
1519                         if (
1520                                 $path === '.' ||
1521                                 $path === '..' ||
1522                                 strpos( $path, './' ) === 0 ||
1523                                 strpos( $path, '../' ) === 0 ||
1524                                 strpos( $path, '/./' ) !== false ||
1525                                 strpos( $path, '/../' ) !== false
1526                         ) {
1527                                 return null;
1528                         }
1529                 }
1530
1531                 return $path;
1532         }
1533 }
1534
1535 /**
1536  * Generic file backend exception for checked and unexpected (e.g. config) exceptions
1537  *
1538  * @ingroup FileBackend
1539  * @since 1.23
1540  */
1541 class FileBackendException extends Exception {
1542 }
1543
1544 /**
1545  * File backend exception for checked exceptions (e.g. I/O errors)
1546  *
1547  * @ingroup FileBackend
1548  * @since 1.22
1549  */
1550 class FileBackendError extends FileBackendException {
1551 }