includes/libs/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  */
  30 use Psr\Log\LoggerAwareInterface;
  31 use Psr\Log\LoggerInterface;
  32 use Wikimedia\ScopedCallback;
  33
  34 /**
  35  * @brief Base class for all file backend classes (including multi-write backends).
  36  *
  37  * This class defines the methods as abstract that subclasses must implement.
  38  * Outside callers can assume that all backends will have these functions.
  39  *
  40  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
  41  * The "backend" portion is unique name for the application to refer to a backend, while
  42  * the "container" portion is a top-level directory of the backend. The "path" portion
  43  * is a relative path that uses UNIX file system (FS) notation, though any particular
  44  * backend may not actually be using a local filesystem. Therefore, the relative paths
  45  * are only virtual.
  46  *
  47  * Backend contents are stored under "domain"-specific container names by default.
  48  * A domain is simply a logical umbrella for entities, such as those belonging to a certain
  49  * application or portion of a website, for example. A domain can be local or global.
  50  * Global (qualified) backends are achieved by configuring the "domain ID" to a constant.
  51  * Global domains are simpler, but local domains can be used by choosing a domain ID based on
  52  * the current context, such as which language of a website is being used.
  53  *
  54  * For legacy reasons, the FSFileBackend class allows manually setting the paths of
  55  * containers to ones that do not respect the "domain ID".
  56  *
  57  * In key/value (object) stores, containers are the only hierarchy (the rest is emulated).
  58  * FS-based backends are somewhat more restrictive due to the existence of real
  59  * directory files; a regular file cannot have the same name as a directory. Other
  60  * backends with virtual directories may not have this limitation. Callers should
  61  * store files in such a way that no files and directories are under the same path.
  62  *
  63  * In general, this class allows for callers to access storage through the same
  64  * interface, without regard to the underlying storage system. However, calling code
  65  * must follow certain patterns and be aware of certain things to ensure compatibility:
  66  *   - a) Always call prepare() on the parent directory before trying to put a file there;
  67  *        key/value stores only need the container to exist first, but filesystems need
  68  *        all the parent directories to exist first (prepare() is aware of all this)
  69  *   - b) Always call clean() on a directory when it might become empty to avoid empty
  70  *        directory buildup on filesystems; key/value stores never have empty directories,
  71  *        so doing this helps preserve consistency in both cases
  72  *   - c) Likewise, do not rely on the existence of empty directories for anything;
  73  *        calling directoryExists() on a path that prepare() was previously called on
  74  *        will return false for key/value stores if there are no files under that path
  75  *   - d) Never alter the resulting FSFile returned from getLocalReference(), as it could
  76  *        either be a copy of the source file in /tmp or the original source file itself
  77  *   - e) Use a file layout that results in never attempting to store files over directories
  78  *        or directories over files; key/value stores allow this but filesystems do not
  79  *   - f) Use ASCII file names (e.g. base32, IDs, hashes) to avoid Unicode issues in Windows
  80  *   - g) Do not assume that move operations are atomic (difficult with key/value stores)
  81  *   - h) Do not assume that file stat or read operations always have immediate consistency;
  82  *        various methods have a "latest" flag that should always be used if up-to-date
  83  *        information is required (this trades performance for correctness as needed)
  84  *   - i) Do not assume that directory listings have immediate consistency
  85  *
  86  * Methods of subclasses should avoid throwing exceptions at all costs.
  87  * As a corollary, external dependencies should be kept to a minimum.
  88  *
  89  * @ingroup FileBackend
  90  * @since 1.19
  91  */
  92 abstract class FileBackend implements LoggerAwareInterface {
  93         /** @var string Unique backend name */
  94         protected $name;
  95
  96         /** @var string Unique domain name */
  97         protected $domainId;
  98
  99         /** @var string Read-only explanation message */
 100         protected $readOnly;
 101
 102         /** @var string When to do operations in parallel */
 103         protected $parallelize;
 104
 105         /** @var int How many operations can be done in parallel */
 106         protected $concurrency;
 107
 108         /** @var string Temporary file directory */
 109         protected $tmpDirectory;
 110
 111         /** @var LockManager */
 112         protected $lockManager;
 113         /** @var FileJournal */
 114         protected $fileJournal;
 115         /** @var LoggerInterface */
 116         protected $logger;
 117         /** @var object|string Class name or object With profileIn/profileOut methods */
 118         protected $profiler;
 119
 120         /** @var callable */
 121         protected $obResetFunc;
 122         /** @var callable */
 123         protected $streamMimeFunc;
 124         /** @var callable */
 125         protected $statusWrapper;
 126
 127         /** Bitfield flags for supported features */
 128         const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
 129         const ATTR_METADATA = 2; // files can be stored with metadata key/values
 130         const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
 131
 132         /**
 133          * Create a new backend instance from configuration.
 134          * This should only be called from within FileBackendGroup.
 135          *
 136          * @param array $config Parameters include:
 137          *   - name : The unique name of this backend.
 138          *      This should consist of alphanumberic, '-', and '_' characters.
 139          *      This name should not be changed after use (e.g. with journaling).
 140          *      Note that the name is *not* used in actual container names.
 141          *   - domainId : Prefix to container names that is unique to this backend.
 142          *      It should only consist of alphanumberic, '-', and '_' characters.
 143          *      This ID is what avoids collisions if multiple logical backends
 144          *      use the same storage system, so this should be set carefully.
 145          *   - lockManager : LockManager object to use for any file locking.
 146          *      If not provided, then no file locking will be enforced.
 147          *   - fileJournal : FileJournal object to use for logging changes to files.
 148          *      If not provided, then change journaling will be disabled.
 149          *   - readOnly : Write operations are disallowed if this is a non-empty string.
 150          *      It should be an explanation for the backend being read-only.
 151          *   - parallelize : When to do file operations in parallel (when possible).
 152          *      Allowed values are "implicit", "explicit" and "off".
 153          *   - concurrency : How many file operations can be done in parallel.
 154          *   - tmpDirectory : Directory to use for temporary files. If this is not set or null,
 155          *      then the backend will try to discover a usable temporary directory.
 156          *   - obResetFunc : alternative callback to clear the output buffer
 157          *   - streamMimeFunc : alternative method to determine the content type from the path
 158          *   - logger : Optional PSR logger object.
 159          *   - profiler : Optional class name or object With profileIn/profileOut methods.
 160          * @throws InvalidArgumentException
 161          */
 162         public function __construct( array $config ) {
 163                 $this->name = $config['name'];
 164                 $this->domainId = isset( $config['domainId'] )
 165                         ? $config['domainId'] // e.g. "my_wiki-en_"
 166                         : $config['wikiId']; // b/c alias
 167                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 168                         throw new InvalidArgumentException( "Backend name '{$this->name}' is invalid." );
 169                 } elseif ( !is_string( $this->domainId ) ) {
 170                         throw new InvalidArgumentException(
 171                                 "Backend domain ID not provided for '{$this->name}'." );
 172                 }
 173                 $this->lockManager = $config['lockManager'] ?? new NullLockManager( [] );
 174                 $this->fileJournal = $config['fileJournal']
 175                         ?? FileJournal::factory( [ 'class' => NullFileJournal::class ], $this->name );
 176                 $this->readOnly = isset( $config['readOnly'] )
 177                         ? (string)$config['readOnly']
 178                         : '';
 179                 $this->parallelize = isset( $config['parallelize'] )
 180                         ? (string)$config['parallelize']
 181                         : 'off';
 182                 $this->concurrency = isset( $config['concurrency'] )
 183                         ? (int)$config['concurrency']
 184                         : 50;
 185                 $this->obResetFunc = $config['obResetFunc'] ?? [ $this, 'resetOutputBuffer' ];
 186                 $this->streamMimeFunc = $config['streamMimeFunc'] ?? null;
 187                 $this->statusWrapper = $config['statusWrapper'] ?? null;
 188
 189                 $this->profiler = $config['profiler'] ?? null;
 190                 $this->logger = $config['logger'] ?? new \Psr\Log\NullLogger();
 191                 $this->statusWrapper = $config['statusWrapper'] ?? null;
 192                 $this->tmpDirectory = $config['tmpDirectory'] ?? null;
 193         }
 194
 195         public function setLogger( LoggerInterface $logger ) {
 196                 $this->logger = $logger;
 197         }
 198
 199         /**
 200          * Get the unique backend name.
 201          * We may have multiple different backends of the same type.
 202          * For example, we can have two Swift backends using different proxies.
 203          *
 204          * @return string
 205          */
 206         final public function getName() {
 207                 return $this->name;
 208         }
 209
 210         /**
 211          * Get the domain identifier used for this backend (possibly empty).
 212          *
 213          * @return string
 214          * @since 1.28
 215          */
 216         final public function getDomainId() {
 217                 return $this->domainId;
 218         }
 219
 220         /**
 221          * Alias to getDomainId()
 222          * @return string
 223          * @since 1.20
 224          */
 225         final public function getWikiId() {
 226                 return $this->getDomainId();
 227         }
 228
 229         /**
 230          * Check if this backend is read-only
 231          *
 232          * @return bool
 233          */
 234         final public function isReadOnly() {
 235                 return ( $this->readOnly != '' );
 236         }
 237
 238         /**
 239          * Get an explanatory message if this backend is read-only
 240          *
 241          * @return string|bool Returns false if the backend is not read-only
 242          */
 243         final public function getReadOnlyReason() {
 244                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 245         }
 246
 247         /**
 248          * Get the a bitfield of extra features supported by the backend medium
 249          *
 250          * @return int Bitfield of FileBackend::ATTR_* flags
 251          * @since 1.23
 252          */
 253         public function getFeatures() {
 254                 return self::ATTR_UNICODE_PATHS;
 255         }
 256
 257         /**
 258          * Check if the backend medium supports a field of extra features
 259          *
 260          * @param int $bitfield Bitfield of FileBackend::ATTR_* flags
 261          * @return bool
 262          * @since 1.23
 263          */
 264         final public function hasFeatures( $bitfield ) {
 265                 return ( $this->getFeatures() & $bitfield ) === $bitfield;
 266         }
 267
 268         /**
 269          * This is the main entry point into the backend for write operations.
 270          * Callers supply an ordered list of operations to perform as a transaction.
 271          * Files will be locked, the stat cache cleared, and then the operations attempted.
 272          * If any serious errors occur, all attempted operations will be rolled back.
 273          *
 274          * $ops is an array of arrays. The outer array holds a list of operations.
 275          * Each inner array is a set of key value pairs that specify an operation.
 276          *
 277          * Supported operations and their parameters. The supported actions are:
 278          *  - create
 279          *  - store
 280          *  - copy
 281          *  - move
 282          *  - delete
 283          *  - describe (since 1.21)
 284          *  - null
 285          *
 286          * FSFile/TempFSFile object support was added in 1.27.
 287          *
 288          * a) Create a new file in storage with the contents of a string
 289          * @code
 290          *     [
 291          *         'op'                  => 'create',
 292          *         'dst'                 => <storage path>,
 293          *         'content'             => <string of new file contents>,
 294          *         'overwrite'           => <boolean>,
 295          *         'overwriteSame'       => <boolean>,
 296          *         'headers'             => <HTTP header name/value map> # since 1.21
 297          *     ]
 298          * @endcode
 299          *
 300          * b) Copy a file system file into storage
 301          * @code
 302          *     [
 303          *         'op'                  => 'store',
 304          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 305          *         'dst'                 => <storage path>,
 306          *         'overwrite'           => <boolean>,
 307          *         'overwriteSame'       => <boolean>,
 308          *         'headers'             => <HTTP header name/value map> # since 1.21
 309          *     ]
 310          * @endcode
 311          *
 312          * c) Copy a file within storage
 313          * @code
 314          *     [
 315          *         'op'                  => 'copy',
 316          *         'src'                 => <storage path>,
 317          *         'dst'                 => <storage path>,
 318          *         'overwrite'           => <boolean>,
 319          *         'overwriteSame'       => <boolean>,
 320          *         'ignoreMissingSource' => <boolean>, # since 1.21
 321          *         'headers'             => <HTTP header name/value map> # since 1.21
 322          *     ]
 323          * @endcode
 324          *
 325          * d) Move a file within storage
 326          * @code
 327          *     [
 328          *         'op'                  => 'move',
 329          *         'src'                 => <storage path>,
 330          *         'dst'                 => <storage path>,
 331          *         'overwrite'           => <boolean>,
 332          *         'overwriteSame'       => <boolean>,
 333          *         'ignoreMissingSource' => <boolean>, # since 1.21
 334          *         'headers'             => <HTTP header name/value map> # since 1.21
 335          *     ]
 336          * @endcode
 337          *
 338          * e) Delete a file within storage
 339          * @code
 340          *     [
 341          *         'op'                  => 'delete',
 342          *         'src'                 => <storage path>,
 343          *         'ignoreMissingSource' => <boolean>
 344          *     ]
 345          * @endcode
 346          *
 347          * f) Update metadata for a file within storage
 348          * @code
 349          *     [
 350          *         'op'                  => 'describe',
 351          *         'src'                 => <storage path>,
 352          *         'headers'             => <HTTP header name/value map>
 353          *     ]
 354          * @endcode
 355          *
 356          * g) Do nothing (no-op)
 357          * @code
 358          *     [
 359          *         'op'                  => 'null',
 360          *     ]
 361          * @endcode
 362          *
 363          * Boolean flags for operations (operation-specific):
 364          *   - ignoreMissingSource : The operation will simply succeed and do
 365          *                           nothing if the source file does not exist.
 366          *   - overwrite           : Any destination file will be overwritten.
 367          *   - overwriteSame       : If a file already exists at the destination with the
 368          *                           same contents, then do nothing to the destination file
 369          *                           instead of giving an error. This does not compare headers.
 370          *                           This option is ignored if 'overwrite' is already provided.
 371          *   - headers             : If supplied, the result of merging these headers with any
 372          *                           existing source file headers (replacing conflicting ones)
 373          *                           will be set as the destination file headers. Headers are
 374          *                           deleted if their value is set to the empty string. When a
 375          *                           file has headers they are included in responses to GET and
 376          *                           HEAD requests to the backing store for that file.
 377          *                           Header values should be no larger than 255 bytes, except for
 378          *                           Content-Disposition. The system might ignore or truncate any
 379          *                           headers that are too long to store (exact limits will vary).
 380          *                           Backends that don't support metadata ignore this. (since 1.21)
 381          *
 382          * $opts is an associative of boolean flags, including:
 383          *   - force               : Operation precondition errors no longer trigger an abort.
 384          *                           Any remaining operations are still attempted. Unexpected
 385          *                           failures may still cause remaining operations to be aborted.
 386          *   - nonLocking          : No locks are acquired for the operations.
 387          *                           This can increase performance for non-critical writes.
 388          *                           This has no effect unless the 'force' flag is set.
 389          *   - nonJournaled        : Don't log this operation batch in the file journal.
 390          *                           This limits the ability of recovery scripts.
 391          *   - parallelize         : Try to do operations in parallel when possible.
 392          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 393          *   - preserveCache       : Don't clear the process cache before checking files.
 394          *                           This should only be used if all entries in the process
 395          *                           cache were added after the files were already locked. (since 1.20)
 396          *
 397          * @note Remarks on locking:
 398          * File system paths given to operations should refer to files that are
 399          * already locked or otherwise safe from modification from other processes.
 400          * Normally these files will be new temp files, which should be adequate.
 401          *
 402          * @par Return value:
 403          *
 404          * This returns a Status, which contains all warnings and fatals that occurred
 405          * during the operation. The 'failCount', 'successCount', and 'success' members
 406          * will reflect each operation attempted.
 407          *
 408          * The StatusValue will be "OK" unless:
 409          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 410          *   - b) significant operation errors occurred and 'force' was not set
 411          *
 412          * @param array $ops List of operations to execute in order
 413          * @param array $opts Batch operation options
 414          * @return StatusValue
 415          */
 416         final public function doOperations( array $ops, array $opts = [] ) {
 417                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 418                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 419                 }
 420                 if ( $ops === [] ) {
 421                         return $this->newStatus(); // nothing to do
 422                 }
 423
 424                 $ops = $this->resolveFSFileObjects( $ops );
 425                 if ( empty( $opts['force'] ) ) { // sanity
 426                         unset( $opts['nonLocking'] );
 427                 }
 428
 429                 /** @noinspection PhpUnusedLocalVariableInspection */
 430                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 431
 432                 return $this->doOperationsInternal( $ops, $opts );
 433         }
 434
 435         /**
 436          * @see FileBackend::doOperations()
 437          * @param array $ops
 438          * @param array $opts
 439          * @return StatusValue
 440          */
 441         abstract protected function doOperationsInternal( array $ops, array $opts );
 442
 443         /**
 444          * Same as doOperations() except it takes a single operation.
 445          * If you are doing a batch of operations that should either
 446          * all succeed or all fail, then use that function instead.
 447          *
 448          * @see FileBackend::doOperations()
 449          *
 450          * @param array $op Operation
 451          * @param array $opts Operation options
 452          * @return StatusValue
 453          */
 454         final public function doOperation( array $op, array $opts = [] ) {
 455                 return $this->doOperations( [ $op ], $opts );
 456         }
 457
 458         /**
 459          * Performs a single create operation.
 460          * This sets $params['op'] to 'create' and passes it to doOperation().
 461          *
 462          * @see FileBackend::doOperation()
 463          *
 464          * @param array $params Operation parameters
 465          * @param array $opts Operation options
 466          * @return StatusValue
 467          */
 468         final public function create( array $params, array $opts = [] ) {
 469                 return $this->doOperation( [ 'op' => 'create' ] + $params, $opts );
 470         }
 471
 472         /**
 473          * Performs a single store operation.
 474          * This sets $params['op'] to 'store' and passes it to doOperation().
 475          *
 476          * @see FileBackend::doOperation()
 477          *
 478          * @param array $params Operation parameters
 479          * @param array $opts Operation options
 480          * @return StatusValue
 481          */
 482         final public function store( array $params, array $opts = [] ) {
 483                 return $this->doOperation( [ 'op' => 'store' ] + $params, $opts );
 484         }
 485
 486         /**
 487          * Performs a single copy operation.
 488          * This sets $params['op'] to 'copy' and passes it to doOperation().
 489          *
 490          * @see FileBackend::doOperation()
 491          *
 492          * @param array $params Operation parameters
 493          * @param array $opts Operation options
 494          * @return StatusValue
 495          */
 496         final public function copy( array $params, array $opts = [] ) {
 497                 return $this->doOperation( [ 'op' => 'copy' ] + $params, $opts );
 498         }
 499
 500         /**
 501          * Performs a single move operation.
 502          * This sets $params['op'] to 'move' and passes it to doOperation().
 503          *
 504          * @see FileBackend::doOperation()
 505          *
 506          * @param array $params Operation parameters
 507          * @param array $opts Operation options
 508          * @return StatusValue
 509          */
 510         final public function move( array $params, array $opts = [] ) {
 511                 return $this->doOperation( [ 'op' => 'move' ] + $params, $opts );
 512         }
 513
 514         /**
 515          * Performs a single delete operation.
 516          * This sets $params['op'] to 'delete' and passes it to doOperation().
 517          *
 518          * @see FileBackend::doOperation()
 519          *
 520          * @param array $params Operation parameters
 521          * @param array $opts Operation options
 522          * @return StatusValue
 523          */
 524         final public function delete( array $params, array $opts = [] ) {
 525                 return $this->doOperation( [ 'op' => 'delete' ] + $params, $opts );
 526         }
 527
 528         /**
 529          * Performs a single describe operation.
 530          * This sets $params['op'] to 'describe' and passes it to doOperation().
 531          *
 532          * @see FileBackend::doOperation()
 533          *
 534          * @param array $params Operation parameters
 535          * @param array $opts Operation options
 536          * @return StatusValue
 537          * @since 1.21
 538          */
 539         final public function describe( array $params, array $opts = [] ) {
 540                 return $this->doOperation( [ 'op' => 'describe' ] + $params, $opts );
 541         }
 542
 543         /**
 544          * Perform a set of independent file operations on some files.
 545          *
 546          * This does no locking, nor journaling, and possibly no stat calls.
 547          * Any destination files that already exist will be overwritten.
 548          * This should *only* be used on non-original files, like cache files.
 549          *
 550          * Supported operations and their parameters:
 551          *  - create
 552          *  - store
 553          *  - copy
 554          *  - move
 555          *  - delete
 556          *  - describe (since 1.21)
 557          *  - null
 558          *
 559          * FSFile/TempFSFile object support was added in 1.27.
 560          *
 561          * a) Create a new file in storage with the contents of a string
 562          * @code
 563          *     [
 564          *         'op'                  => 'create',
 565          *         'dst'                 => <storage path>,
 566          *         'content'             => <string of new file contents>,
 567          *         'headers'             => <HTTP header name/value map> # since 1.21
 568          *     ]
 569          * @endcode
 570          *
 571          * b) Copy a file system file into storage
 572          * @code
 573          *     [
 574          *         'op'                  => 'store',
 575          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 576          *         'dst'                 => <storage path>,
 577          *         'headers'             => <HTTP header name/value map> # since 1.21
 578          *     ]
 579          * @endcode
 580          *
 581          * c) Copy a file within storage
 582          * @code
 583          *     [
 584          *         'op'                  => 'copy',
 585          *         'src'                 => <storage path>,
 586          *         'dst'                 => <storage path>,
 587          *         'ignoreMissingSource' => <boolean>, # since 1.21
 588          *         'headers'             => <HTTP header name/value map> # since 1.21
 589          *     ]
 590          * @endcode
 591          *
 592          * d) Move a file within storage
 593          * @code
 594          *     [
 595          *         'op'                  => 'move',
 596          *         'src'                 => <storage path>,
 597          *         'dst'                 => <storage path>,
 598          *         'ignoreMissingSource' => <boolean>, # since 1.21
 599          *         'headers'             => <HTTP header name/value map> # since 1.21
 600          *     ]
 601          * @endcode
 602          *
 603          * e) Delete a file within storage
 604          * @code
 605          *     [
 606          *         'op'                  => 'delete',
 607          *         'src'                 => <storage path>,
 608          *         'ignoreMissingSource' => <boolean>
 609          *     ]
 610          * @endcode
 611          *
 612          * f) Update metadata for a file within storage
 613          * @code
 614          *     [
 615          *         'op'                  => 'describe',
 616          *         'src'                 => <storage path>,
 617          *         'headers'             => <HTTP header name/value map>
 618          *     ]
 619          * @endcode
 620          *
 621          * g) Do nothing (no-op)
 622          * @code
 623          *     [
 624          *         'op'                  => 'null',
 625          *     ]
 626          * @endcode
 627          *
 628          * @par Boolean flags for operations (operation-specific):
 629          *   - ignoreMissingSource : The operation will simply succeed and do
 630          *                           nothing if the source file does not exist.
 631          *   - headers             : If supplied with a header name/value map, the backend will
 632          *                           reply with these headers when GETs/HEADs of the destination
 633          *                           file are made. Header values should be smaller than 256 bytes.
 634          *                           Content-Disposition headers can be longer, though the system
 635          *                           might ignore or truncate ones that are too long to store.
 636          *                           Existing headers will remain, but these will replace any
 637          *                           conflicting previous headers, and headers will be removed
 638          *                           if they are set to an empty string.
 639          *                           Backends that don't support metadata ignore this. (since 1.21)
 640          *
 641          * $opts is an associative of boolean flags, including:
 642          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 643          *
 644          * @par Return value:
 645          * This returns a Status, which contains all warnings and fatals that occurred
 646          * during the operation. The 'failCount', 'successCount', and 'success' members
 647          * will reflect each operation attempted for the given files. The StatusValue will be
 648          * considered "OK" as long as no fatal errors occurred.
 649          *
 650          * @param array $ops Set of operations to execute
 651          * @param array $opts Batch operation options
 652          * @return StatusValue
 653          * @since 1.20
 654          */
 655         final public function doQuickOperations( array $ops, array $opts = [] ) {
 656                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 657                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 658                 }
 659                 if ( $ops === [] ) {
 660                         return $this->newStatus(); // nothing to do
 661                 }
 662
 663                 $ops = $this->resolveFSFileObjects( $ops );
 664                 foreach ( $ops as &$op ) {
 665                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 666                 }
 667
 668                 /** @noinspection PhpUnusedLocalVariableInspection */
 669                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 670
 671                 return $this->doQuickOperationsInternal( $ops );
 672         }
 673
 674         /**
 675          * @see FileBackend::doQuickOperations()
 676          * @param array $ops
 677          * @return StatusValue
 678          * @since 1.20
 679          */
 680         abstract protected function doQuickOperationsInternal( array $ops );
 681
 682         /**
 683          * Same as doQuickOperations() except it takes a single operation.
 684          * If you are doing a batch of operations, then use that function instead.
 685          *
 686          * @see FileBackend::doQuickOperations()
 687          *
 688          * @param array $op Operation
 689          * @return StatusValue
 690          * @since 1.20
 691          */
 692         final public function doQuickOperation( array $op ) {
 693                 return $this->doQuickOperations( [ $op ] );
 694         }
 695
 696         /**
 697          * Performs a single quick create operation.
 698          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 699          *
 700          * @see FileBackend::doQuickOperation()
 701          *
 702          * @param array $params Operation parameters
 703          * @return StatusValue
 704          * @since 1.20
 705          */
 706         final public function quickCreate( array $params ) {
 707                 return $this->doQuickOperation( [ 'op' => 'create' ] + $params );
 708         }
 709
 710         /**
 711          * Performs a single quick store operation.
 712          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 713          *
 714          * @see FileBackend::doQuickOperation()
 715          *
 716          * @param array $params Operation parameters
 717          * @return StatusValue
 718          * @since 1.20
 719          */
 720         final public function quickStore( array $params ) {
 721                 return $this->doQuickOperation( [ 'op' => 'store' ] + $params );
 722         }
 723
 724         /**
 725          * Performs a single quick copy operation.
 726          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 727          *
 728          * @see FileBackend::doQuickOperation()
 729          *
 730          * @param array $params Operation parameters
 731          * @return StatusValue
 732          * @since 1.20
 733          */
 734         final public function quickCopy( array $params ) {
 735                 return $this->doQuickOperation( [ 'op' => 'copy' ] + $params );
 736         }
 737
 738         /**
 739          * Performs a single quick move operation.
 740          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 741          *
 742          * @see FileBackend::doQuickOperation()
 743          *
 744          * @param array $params Operation parameters
 745          * @return StatusValue
 746          * @since 1.20
 747          */
 748         final public function quickMove( array $params ) {
 749                 return $this->doQuickOperation( [ 'op' => 'move' ] + $params );
 750         }
 751
 752         /**
 753          * Performs a single quick delete operation.
 754          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 755          *
 756          * @see FileBackend::doQuickOperation()
 757          *
 758          * @param array $params Operation parameters
 759          * @return StatusValue
 760          * @since 1.20
 761          */
 762         final public function quickDelete( array $params ) {
 763                 return $this->doQuickOperation( [ 'op' => 'delete' ] + $params );
 764         }
 765
 766         /**
 767          * Performs a single quick describe operation.
 768          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 769          *
 770          * @see FileBackend::doQuickOperation()
 771          *
 772          * @param array $params Operation parameters
 773          * @return StatusValue
 774          * @since 1.21
 775          */
 776         final public function quickDescribe( array $params ) {
 777                 return $this->doQuickOperation( [ 'op' => 'describe' ] + $params );
 778         }
 779
 780         /**
 781          * Concatenate a list of storage files into a single file system file.
 782          * The target path should refer to a file that is already locked or
 783          * otherwise safe from modification from other processes. Normally,
 784          * the file will be a new temp file, which should be adequate.
 785          *
 786          * @param array $params Operation parameters, include:
 787          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 788          *   - dst         : file system path to 0-byte temp file
 789          *   - parallelize : try to do operations in parallel when possible
 790          * @return StatusValue
 791          */
 792         abstract public function concatenate( array $params );
 793
 794         /**
 795          * Prepare a storage directory for usage.
 796          * This will create any required containers and parent directories.
 797          * Backends using key/value stores only need to create the container.
 798          *
 799          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 800          * except they are only applied *if* the directory/container had to be created.
 801          * These flags should always be set for directories that have private files.
 802          * However, setting them is not guaranteed to actually do anything.
 803          * Additional server configuration may be needed to achieve the desired effect.
 804          *
 805          * @param array $params Parameters include:
 806          *   - dir            : storage directory
 807          *   - noAccess       : try to deny file access (since 1.20)
 808          *   - noListing      : try to deny file listing (since 1.20)
 809          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 810          * @return StatusValue
 811          */
 812         final public function prepare( array $params ) {
 813                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 814                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 815                 }
 816                 /** @noinspection PhpUnusedLocalVariableInspection */
 817                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 818                 return $this->doPrepare( $params );
 819         }
 820
 821         /**
 822          * @see FileBackend::prepare()
 823          * @param array $params
 824          * @return StatusValue
 825          */
 826         abstract protected function doPrepare( array $params );
 827
 828         /**
 829          * Take measures to block web access to a storage directory and
 830          * the container it belongs to. FS backends might add .htaccess
 831          * files whereas key/value store backends might revoke container
 832          * access to the storage user representing end-users in web requests.
 833          *
 834          * This is not guaranteed to actually make files or listings publicly hidden.
 835          * Additional server configuration may be needed to achieve the desired effect.
 836          *
 837          * @param array $params Parameters include:
 838          *   - dir            : storage directory
 839          *   - noAccess       : try to deny file access
 840          *   - noListing      : try to deny file listing
 841          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 842          * @return StatusValue
 843          */
 844         final public function secure( array $params ) {
 845                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 846                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 847                 }
 848                 /** @noinspection PhpUnusedLocalVariableInspection */
 849                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 850                 return $this->doSecure( $params );
 851         }
 852
 853         /**
 854          * @see FileBackend::secure()
 855          * @param array $params
 856          * @return StatusValue
 857          */
 858         abstract protected function doSecure( array $params );
 859
 860         /**
 861          * Remove measures to block web access to a storage directory and
 862          * the container it belongs to. FS backends might remove .htaccess
 863          * files whereas key/value store backends might grant container
 864          * access to the storage user representing end-users in web requests.
 865          * This essentially can undo the result of secure() calls.
 866          *
 867          * This is not guaranteed to actually make files or listings publicly viewable.
 868          * Additional server configuration may be needed to achieve the desired effect.
 869          *
 870          * @param array $params Parameters include:
 871          *   - dir            : storage directory
 872          *   - access         : try to allow file access
 873          *   - listing        : try to allow file listing
 874          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 875          * @return StatusValue
 876          * @since 1.20
 877          */
 878         final public function publish( array $params ) {
 879                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 880                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 881                 }
 882                 /** @noinspection PhpUnusedLocalVariableInspection */
 883                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 884                 return $this->doPublish( $params );
 885         }
 886
 887         /**
 888          * @see FileBackend::publish()
 889          * @param array $params
 890          * @return StatusValue
 891          */
 892         abstract protected function doPublish( array $params );
 893
 894         /**
 895          * Delete a storage directory if it is empty.
 896          * Backends using key/value stores may do nothing unless the directory
 897          * is that of an empty container, in which case it will be deleted.
 898          *
 899          * @param array $params Parameters include:
 900          *   - dir            : storage directory
 901          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 902          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 903          * @return StatusValue
 904          */
 905         final public function clean( array $params ) {
 906                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 907                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 908                 }
 909                 /** @noinspection PhpUnusedLocalVariableInspection */
 910                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 911                 return $this->doClean( $params );
 912         }
 913
 914         /**
 915          * @see FileBackend::clean()
 916          * @param array $params
 917          * @return StatusValue
 918          */
 919         abstract protected function doClean( array $params );
 920
 921         /**
 922          * Check if a file exists at a storage path in the backend.
 923          * This returns false if only a directory exists at the path.
 924          *
 925          * @param array $params Parameters include:
 926          *   - src    : source storage path
 927          *   - latest : use the latest available data
 928          * @return bool|null Returns null on failure
 929          */
 930         abstract public function fileExists( array $params );
 931
 932         /**
 933          * Get the last-modified timestamp of the file at a storage path.
 934          *
 935          * @param array $params Parameters include:
 936          *   - src    : source storage path
 937          *   - latest : use the latest available data
 938          * @return string|bool TS_MW timestamp or false on failure
 939          */
 940         abstract public function getFileTimestamp( array $params );
 941
 942         /**
 943          * Get the contents of a file at a storage path in the backend.
 944          * This should be avoided for potentially large files.
 945          *
 946          * @param array $params Parameters include:
 947          *   - src    : source storage path
 948          *   - latest : use the latest available data
 949          * @return string|bool Returns false on failure
 950          */
 951         final public function getFileContents( array $params ) {
 952                 $contents = $this->getFileContentsMulti(
 953                         [ 'srcs' => [ $params['src'] ] ] + $params );
 954
 955                 return $contents[$params['src']];
 956         }
 957
 958         /**
 959          * Like getFileContents() except it takes an array of storage paths
 960          * and returns a map of storage paths to strings (or null on failure).
 961          * The map keys (paths) are in the same order as the provided list of paths.
 962          *
 963          * @see FileBackend::getFileContents()
 964          *
 965          * @param array $params Parameters include:
 966          *   - srcs        : list of source storage paths
 967          *   - latest      : use the latest available data
 968          *   - parallelize : try to do operations in parallel when possible
 969          * @return array Map of (path name => string or false on failure)
 970          * @since 1.20
 971          */
 972         abstract public function getFileContentsMulti( array $params );
 973
 974         /**
 975          * Get metadata about a file at a storage path in the backend.
 976          * If the file does not exist, then this returns false.
 977          * Otherwise, the result is an associative array that includes:
 978          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 979          *   - metadata : map of file metadata (name => value)
 980          * Metadata keys and headers names will be returned in all lower-case.
 981          * Additional values may be included for internal use only.
 982          *
 983          * Use FileBackend::hasFeatures() to check how well this is supported.
 984          *
 985          * @param array $params
 986          * $params include:
 987          *   - src    : source storage path
 988          *   - latest : use the latest available data
 989          * @return array|bool Returns false on failure
 990          * @since 1.23
 991          */
 992         abstract public function getFileXAttributes( array $params );
 993
 994         /**
 995          * Get the size (bytes) of a file at a storage path in the backend.
 996          *
 997          * @param array $params Parameters include:
 998          *   - src    : source storage path
 999          *   - latest : use the latest available data
1000          * @return int|bool Returns false on failure
1001          */
1002         abstract public function getFileSize( array $params );
1003
1004         /**
1005          * Get quick information about a file at a storage path in the backend.
1006          * If the file does not exist, then this returns false.
1007          * Otherwise, the result is an associative array that includes:
1008          *   - mtime  : the last-modified timestamp (TS_MW)
1009          *   - size   : the file size (bytes)
1010          * Additional values may be included for internal use only.
1011          *
1012          * @param array $params Parameters include:
1013          *   - src    : source storage path
1014          *   - latest : use the latest available data
1015          * @return array|bool|null Returns null on failure
1016          */
1017         abstract public function getFileStat( array $params );
1018
1019         /**
1020          * Get a SHA-1 hash of the file at a storage path in the backend.
1021          *
1022          * @param array $params Parameters include:
1023          *   - src    : source storage path
1024          *   - latest : use the latest available data
1025          * @return string|bool Hash string or false on failure
1026          */
1027         abstract public function getFileSha1Base36( array $params );
1028
1029         /**
1030          * Get the properties of the file at a storage path in the backend.
1031          * This gives the result of FSFile::getProps() on a local copy of the file.
1032          *
1033          * @param array $params Parameters include:
1034          *   - src    : source storage path
1035          *   - latest : use the latest available data
1036          * @return array Returns FSFile::placeholderProps() on failure
1037          */
1038         abstract public function getFileProps( array $params );
1039
1040         /**
1041          * Stream the file at a storage path in the backend.
1042          *
1043          * If the file does not exists, an HTTP 404 error will be given.
1044          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
1045          * will be sent if streaming began, while none will be sent otherwise.
1046          * Implementations should flush the output buffer before sending data.
1047          *
1048          * @param array $params Parameters include:
1049          *   - src      : source storage path
1050          *   - headers  : list of additional HTTP headers to send if the file exists
1051          *   - options  : HTTP request header map with lower case keys (since 1.28). Supports:
1052          *                range             : format is "bytes=(\d*-\d*)"
1053          *                if-modified-since : format is an HTTP date
1054          *   - headless : only include the body (and headers from "headers") (since 1.28)
1055          *   - latest   : use the latest available data
1056          *   - allowOB  : preserve any output buffers (since 1.28)
1057          * @return StatusValue
1058          */
1059         abstract public function streamFile( array $params );
1060
1061         /**
1062          * Returns a file system file, identical to the file at a storage path.
1063          * The file returned is either:
1064          *   - a) A local copy of the file at a storage path in the backend.
1065          *        The temporary copy will have the same extension as the source.
1066          *   - b) An original of the file at a storage path in the backend.
1067          * Temporary files may be purged when the file object falls out of scope.
1068          *
1069          * Write operations should *never* be done on this file as some backends
1070          * may do internal tracking or may be instances of FileBackendMultiWrite.
1071          * In that latter case, there are copies of the file that must stay in sync.
1072          * Additionally, further calls to this function may return the same file.
1073          *
1074          * @param array $params Parameters include:
1075          *   - src    : source storage path
1076          *   - latest : use the latest available data
1077          * @return FSFile|null Returns null on failure
1078          */
1079         final public function getLocalReference( array $params ) {
1080                 $fsFiles = $this->getLocalReferenceMulti(
1081                         [ 'srcs' => [ $params['src'] ] ] + $params );
1082
1083                 return $fsFiles[$params['src']];
1084         }
1085
1086         /**
1087          * Like getLocalReference() except it takes an array of storage paths
1088          * and returns a map of storage paths to FSFile objects (or null on failure).
1089          * The map keys (paths) are in the same order as the provided list of paths.
1090          *
1091          * @see FileBackend::getLocalReference()
1092          *
1093          * @param array $params Parameters include:
1094          *   - srcs        : list of source storage paths
1095          *   - latest      : use the latest available data
1096          *   - parallelize : try to do operations in parallel when possible
1097          * @return array Map of (path name => FSFile or null on failure)
1098          * @since 1.20
1099          */
1100         abstract public function getLocalReferenceMulti( array $params );
1101
1102         /**
1103          * Get a local copy on disk of the file at a storage path in the backend.
1104          * The temporary copy will have the same file extension as the source.
1105          * Temporary files may be purged when the file object falls out of scope.
1106          *
1107          * @param array $params Parameters include:
1108          *   - src    : source storage path
1109          *   - latest : use the latest available data
1110          * @return TempFSFile|null Returns null on failure
1111          */
1112         final public function getLocalCopy( array $params ) {
1113                 $tmpFiles = $this->getLocalCopyMulti(
1114                         [ 'srcs' => [ $params['src'] ] ] + $params );
1115
1116                 return $tmpFiles[$params['src']];
1117         }
1118
1119         /**
1120          * Like getLocalCopy() except it takes an array of storage paths and
1121          * returns a map of storage paths to TempFSFile objects (or null on failure).
1122          * The map keys (paths) are in the same order as the provided list of paths.
1123          *
1124          * @see FileBackend::getLocalCopy()
1125          *
1126          * @param array $params Parameters include:
1127          *   - srcs        : list of source storage paths
1128          *   - latest      : use the latest available data
1129          *   - parallelize : try to do operations in parallel when possible
1130          * @return array Map of (path name => TempFSFile or null on failure)
1131          * @since 1.20
1132          */
1133         abstract public function getLocalCopyMulti( array $params );
1134
1135         /**
1136          * Return an HTTP URL to a given file that requires no authentication to use.
1137          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1138          * This will return null if the backend cannot make an HTTP URL for the file.
1139          *
1140          * This is useful for key/value stores when using scripts that seek around
1141          * large files and those scripts (and the backend) support HTTP Range headers.
1142          * Otherwise, one would need to use getLocalReference(), which involves loading
1143          * the entire file on to local disk.
1144          *
1145          * @param array $params Parameters include:
1146          *   - src : source storage path
1147          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1148          * @return string|null
1149          * @since 1.21
1150          */
1151         abstract public function getFileHttpUrl( array $params );
1152
1153         /**
1154          * Check if a directory exists at a given storage path.
1155          * Backends using key/value stores will check if the path is a
1156          * virtual directory, meaning there are files under the given directory.
1157          *
1158          * Storage backends with eventual consistency might return stale data.
1159          *
1160          * @param array $params Parameters include:
1161          *   - dir : storage directory
1162          * @return bool|null Returns null on failure
1163          * @since 1.20
1164          */
1165         abstract public function directoryExists( array $params );
1166
1167         /**
1168          * Get an iterator to list *all* directories under a storage directory.
1169          * If the directory is of the form "mwstore://backend/container",
1170          * then all directories in the container will be listed.
1171          * If the directory is of form "mwstore://backend/container/dir",
1172          * then all directories directly under that directory will be listed.
1173          * Results will be storage directories relative to the given directory.
1174          *
1175          * Storage backends with eventual consistency might return stale data.
1176          *
1177          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1178          *
1179          * @param array $params Parameters include:
1180          *   - dir     : storage directory
1181          *   - topOnly : only return direct child dirs of the directory
1182          * @return Traversable|array|null Returns null on failure
1183          * @since 1.20
1184          */
1185         abstract public function getDirectoryList( array $params );
1186
1187         /**
1188          * Same as FileBackend::getDirectoryList() except only lists
1189          * directories that are immediately under the given directory.
1190          *
1191          * Storage backends with eventual consistency might return stale data.
1192          *
1193          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1194          *
1195          * @param array $params Parameters include:
1196          *   - dir : storage directory
1197          * @return Traversable|array|null Returns null on failure
1198          * @since 1.20
1199          */
1200         final public function getTopDirectoryList( array $params ) {
1201                 return $this->getDirectoryList( [ 'topOnly' => true ] + $params );
1202         }
1203
1204         /**
1205          * Get an iterator to list *all* stored files under a storage directory.
1206          * If the directory is of the form "mwstore://backend/container",
1207          * then all files in the container will be listed.
1208          * If the directory is of form "mwstore://backend/container/dir",
1209          * then all files under that directory will be listed.
1210          * Results will be storage paths relative to the given directory.
1211          *
1212          * Storage backends with eventual consistency might return stale data.
1213          *
1214          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1215          *
1216          * @param array $params Parameters include:
1217          *   - dir        : storage directory
1218          *   - topOnly    : only return direct child files of the directory (since 1.20)
1219          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1220          * @return Traversable|array|null Returns null on failure
1221          */
1222         abstract public function getFileList( array $params );
1223
1224         /**
1225          * Same as FileBackend::getFileList() except only lists
1226          * files that are immediately under the given directory.
1227          *
1228          * Storage backends with eventual consistency might return stale data.
1229          *
1230          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1231          *
1232          * @param array $params Parameters include:
1233          *   - dir        : storage directory
1234          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1235          * @return Traversable|array|null Returns null on failure
1236          * @since 1.20
1237          */
1238         final public function getTopFileList( array $params ) {
1239                 return $this->getFileList( [ 'topOnly' => true ] + $params );
1240         }
1241
1242         /**
1243          * Preload persistent file stat cache and property cache into in-process cache.
1244          * This should be used when stat calls will be made on a known list of a many files.
1245          *
1246          * @see FileBackend::getFileStat()
1247          *
1248          * @param array $paths Storage paths
1249          */
1250         abstract public function preloadCache( array $paths );
1251
1252         /**
1253          * Invalidate any in-process file stat and property cache.
1254          * If $paths is given, then only the cache for those files will be cleared.
1255          *
1256          * @see FileBackend::getFileStat()
1257          *
1258          * @param array|null $paths Storage paths (optional)
1259          */
1260         abstract public function clearCache( array $paths = null );
1261
1262         /**
1263          * Preload file stat information (concurrently if possible) into in-process cache.
1264          *
1265          * This should be used when stat calls will be made on a known list of a many files.
1266          * This does not make use of the persistent file stat cache.
1267          *
1268          * @see FileBackend::getFileStat()
1269          *
1270          * @param array $params Parameters include:
1271          *   - srcs        : list of source storage paths
1272          *   - latest      : use the latest available data
1273          * @return bool All requests proceeded without I/O errors (since 1.24)
1274          * @since 1.23
1275          */
1276         abstract public function preloadFileStat( array $params );
1277
1278         /**
1279          * Lock the files at the given storage paths in the backend.
1280          * This will either lock all the files or none (on failure).
1281          *
1282          * Callers should consider using getScopedFileLocks() instead.
1283          *
1284          * @param array $paths Storage paths
1285          * @param int $type LockManager::LOCK_* constant
1286          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1287          * @return StatusValue
1288          */
1289         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1290                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1291
1292                 return $this->wrapStatus( $this->lockManager->lock( $paths, $type, $timeout ) );
1293         }
1294
1295         /**
1296          * Unlock the files at the given storage paths in the backend.
1297          *
1298          * @param array $paths Storage paths
1299          * @param int $type LockManager::LOCK_* constant
1300          * @return StatusValue
1301          */
1302         final public function unlockFiles( array $paths, $type ) {
1303                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1304
1305                 return $this->wrapStatus( $this->lockManager->unlock( $paths, $type ) );
1306         }
1307
1308         /**
1309          * Lock the files at the given storage paths in the backend.
1310          * This will either lock all the files or none (on failure).
1311          * On failure, the StatusValue object will be updated with errors.
1312          *
1313          * Once the return value goes out scope, the locks will be released and
1314          * the StatusValue updated. Unlock fatals will not change the StatusValue "OK" value.
1315          *
1316          * @see ScopedLock::factory()
1317          *
1318          * @param array $paths List of storage paths or map of lock types to path lists
1319          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1320          * @param StatusValue $status StatusValue to update on lock/unlock
1321          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1322          * @return ScopedLock|null Returns null on failure
1323          */
1324         final public function getScopedFileLocks(
1325                 array $paths, $type, StatusValue $status, $timeout = 0
1326         ) {
1327                 if ( $type === 'mixed' ) {
1328                         foreach ( $paths as &$typePaths ) {
1329                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1330                         }
1331                 } else {
1332                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1333                 }
1334
1335                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1336         }
1337
1338         /**
1339          * Get an array of scoped locks needed for a batch of file operations.
1340          *
1341          * Normally, FileBackend::doOperations() handles locking, unless
1342          * the 'nonLocking' param is passed in. This function is useful if you
1343          * want the files to be locked for a broader scope than just when the
1344          * files are changing. For example, if you need to update DB metadata,
1345          * you may want to keep the files locked until finished.
1346          *
1347          * @see FileBackend::doOperations()
1348          *
1349          * @param array $ops List of file operations to FileBackend::doOperations()
1350          * @param StatusValue $status StatusValue to update on lock/unlock
1351          * @return ScopedLock|null
1352          * @since 1.20
1353          */
1354         abstract public function getScopedLocksForOps( array $ops, StatusValue $status );
1355
1356         /**
1357          * Get the root storage path of this backend.
1358          * All container paths are "subdirectories" of this path.
1359          *
1360          * @return string Storage path
1361          * @since 1.20
1362          */
1363         final public function getRootStoragePath() {
1364                 return "mwstore://{$this->name}";
1365         }
1366
1367         /**
1368          * Get the storage path for the given container for this backend
1369          *
1370          * @param string $container Container name
1371          * @return string Storage path
1372          * @since 1.21
1373          */
1374         final public function getContainerStoragePath( $container ) {
1375                 return $this->getRootStoragePath() . "/{$container}";
1376         }
1377
1378         /**
1379          * Get the file journal object for this backend
1380          *
1381          * @return FileJournal
1382          */
1383         final public function getJournal() {
1384                 return $this->fileJournal;
1385         }
1386
1387         /**
1388          * Convert FSFile 'src' paths to string paths (with an 'srcRef' field set to the FSFile)
1389          *
1390          * The 'srcRef' field keeps any TempFSFile objects in scope for the backend to have it
1391          * around as long it needs (which may vary greatly depending on configuration)
1392          *
1393          * @param array $ops File operation batch for FileBaclend::doOperations()
1394          * @return array File operation batch
1395          */
1396         protected function resolveFSFileObjects( array $ops ) {
1397                 foreach ( $ops as &$op ) {
1398                         $src = $op['src'] ?? null;
1399                         if ( $src instanceof FSFile ) {
1400                                 $op['srcRef'] = $src;
1401                                 $op['src'] = $src->getPath();
1402                         }
1403                 }
1404                 unset( $op );
1405
1406                 return $ops;
1407         }
1408
1409         /**
1410          * Check if a given path is a "mwstore://" path.
1411          * This does not do any further validation or any existence checks.
1412          *
1413          * @param string $path
1414          * @return bool
1415          */
1416         final public static function isStoragePath( $path ) {
1417                 return ( strpos( $path, 'mwstore://' ) === 0 );
1418         }
1419
1420         /**
1421          * Split a storage path into a backend name, a container name,
1422          * and a relative file path. The relative path may be the empty string.
1423          * This does not do any path normalization or traversal checks.
1424          *
1425          * @param string $storagePath
1426          * @return array (backend, container, rel object) or (null, null, null)
1427          */
1428         final public static function splitStoragePath( $storagePath ) {
1429                 if ( self::isStoragePath( $storagePath ) ) {
1430                         // Remove the "mwstore://" prefix and split the path
1431                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1432                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1433                                 if ( count( $parts ) == 3 ) {
1434                                         return $parts; // e.g. "backend/container/path"
1435                                 } else {
1436                                         return [ $parts[0], $parts[1], '' ]; // e.g. "backend/container"
1437                                 }
1438                         }
1439                 }
1440
1441                 return [ null, null, null ];
1442         }
1443
1444         /**
1445          * Normalize a storage path by cleaning up directory separators.
1446          * Returns null if the path is not of the format of a valid storage path.
1447          *
1448          * @param string $storagePath
1449          * @return string|null
1450          */
1451         final public static function normalizeStoragePath( $storagePath ) {
1452                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1453                 if ( $relPath !== null ) { // must be for this backend
1454                         $relPath = self::normalizeContainerPath( $relPath );
1455                         if ( $relPath !== null ) {
1456                                 return ( $relPath != '' )
1457                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1458                                         : "mwstore://{$backend}/{$container}";
1459                         }
1460                 }
1461
1462                 return null;
1463         }
1464
1465         /**
1466          * Get the parent storage directory of a storage path.
1467          * This returns a path like "mwstore://backend/container",
1468          * "mwstore://backend/container/...", or null if there is no parent.
1469          *
1470          * @param string $storagePath
1471          * @return string|null
1472          */
1473         final public static function parentStoragePath( $storagePath ) {
1474                 $storagePath = dirname( $storagePath );
1475                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1476
1477                 return ( $rel === null ) ? null : $storagePath;
1478         }
1479
1480         /**
1481          * Get the final extension from a storage or FS path
1482          *
1483          * @param string $path
1484          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1485          * @return string
1486          */
1487         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1488                 $i = strrpos( $path, '.' );
1489                 $ext = $i ? substr( $path, $i + 1 ) : '';
1490
1491                 if ( $case === 'lowercase' ) {
1492                         $ext = strtolower( $ext );
1493                 } elseif ( $case === 'uppercase' ) {
1494                         $ext = strtoupper( $ext );
1495                 }
1496
1497                 return $ext;
1498         }
1499
1500         /**
1501          * Check if a relative path has no directory traversals
1502          *
1503          * @param string $path
1504          * @return bool
1505          * @since 1.20
1506          */
1507         final public static function isPathTraversalFree( $path ) {
1508                 return ( self::normalizeContainerPath( $path ) !== null );
1509         }
1510
1511         /**
1512          * Build a Content-Disposition header value per RFC 6266.
1513          *
1514          * @param string $type One of (attachment, inline)
1515          * @param string $filename Suggested file name (should not contain slashes)
1516          * @throws FileBackendError
1517          * @return string
1518          * @since 1.20
1519          */
1520         final public static function makeContentDisposition( $type, $filename = '' ) {
1521                 $parts = [];
1522
1523                 $type = strtolower( $type );
1524                 if ( !in_array( $type, [ 'inline', 'attachment' ] ) ) {
1525                         throw new InvalidArgumentException( "Invalid Content-Disposition type '$type'." );
1526                 }
1527                 $parts[] = $type;
1528
1529                 if ( strlen( $filename ) ) {
1530                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1531                 }
1532
1533                 return implode( ';', $parts );
1534         }
1535
1536         /**
1537          * Validate and normalize a relative storage path.
1538          * Null is returned if the path involves directory traversal.
1539          * Traversal is insecure for FS backends and broken for others.
1540          *
1541          * This uses the same traversal protection as Title::secureAndSplit().
1542          *
1543          * @param string $path Storage path relative to a container
1544          * @return string|null
1545          */
1546         final protected static function normalizeContainerPath( $path ) {
1547                 // Normalize directory separators
1548                 $path = strtr( $path, '\\', '/' );
1549                 // Collapse any consecutive directory separators
1550                 $path = preg_replace( '![/]{2,}!', '/', $path );
1551                 // Remove any leading directory separator
1552                 $path = ltrim( $path, '/' );
1553                 // Use the same traversal protection as Title::secureAndSplit()
1554                 if ( strpos( $path, '.' ) !== false ) {
1555                         if (
1556                                 $path === '.' ||
1557                                 $path === '..' ||
1558                                 strpos( $path, './' ) === 0 ||
1559                                 strpos( $path, '../' ) === 0 ||
1560                                 strpos( $path, '/./' ) !== false ||
1561                                 strpos( $path, '/../' ) !== false
1562                         ) {
1563                                 return null;
1564                         }
1565                 }
1566
1567                 return $path;
1568         }
1569
1570         /**
1571          * Yields the result of the status wrapper callback on either:
1572          *   - StatusValue::newGood() if this method is called without parameters
1573          *   - StatusValue::newFatal() with all parameters to this method if passed in
1574          *
1575          * @param string $args,...
1576          * @return StatusValue
1577          */
1578         final protected function newStatus() {
1579                 $args = func_get_args();
1580                 if ( count( $args ) ) {
1581                         $sv = StatusValue::newFatal( ...$args );
1582                 } else {
1583                         $sv = StatusValue::newGood();
1584                 }
1585
1586                 return $this->wrapStatus( $sv );
1587         }
1588
1589         /**
1590          * @param StatusValue $sv
1591          * @return StatusValue Modified status or StatusValue subclass
1592          */
1593         final protected function wrapStatus( StatusValue $sv ) {
1594                 return $this->statusWrapper ? call_user_func( $this->statusWrapper, $sv ) : $sv;
1595         }
1596
1597         /**
1598          * @param string $section
1599          * @return ScopedCallback|null
1600          */
1601         protected function scopedProfileSection( $section ) {
1602                 if ( $this->profiler ) {
1603                         call_user_func( [ $this->profiler, 'profileIn' ], $section );
1604                         return new ScopedCallback( [ $this->profiler, 'profileOut' ], [ $section ] );
1605                 }
1606
1607                 return null;
1608         }
1609
1610         protected function resetOutputBuffer() {
1611                 while ( ob_get_status() ) {
1612                         if ( !ob_end_clean() ) {
1613                                 // Could not remove output buffer handler; abort now
1614                                 // to avoid getting in some kind of infinite loop.
1615                                 break;
1616                         }
1617                 }
1618         }
1619 }