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 MediaWiki\FileBackend\FSFile\TempFSFileFactory;
  31 use Psr\Log\LoggerAwareInterface;
  32 use Psr\Log\LoggerInterface;
  33 use Wikimedia\ScopedCallback;
  34 use Psr\Log\NullLogger;
  35
  36 /**
  37  * @brief Base class for all file backend classes (including multi-write backends).
  38  *
  39  * This class defines the methods as abstract that subclasses must implement.
  40  * Outside callers can assume that all backends will have these functions.
  41  *
  42  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
  43  * The "backend" portion is unique name for the application to refer to a backend, while
  44  * the "container" portion is a top-level directory of the backend. The "path" portion
  45  * is a relative path that uses UNIX file system (FS) notation, though any particular
  46  * backend may not actually be using a local filesystem. Therefore, the relative paths
  47  * are only virtual.
  48  *
  49  * Backend contents are stored under "domain"-specific container names by default.
  50  * A domain is simply a logical umbrella for entities, such as those belonging to a certain
  51  * application or portion of a website, for example. A domain can be local or global.
  52  * Global (qualified) backends are achieved by configuring the "domain ID" to a constant.
  53  * Global domains are simpler, but local domains can be used by choosing a domain ID based on
  54  * the current context, such as which language of a website is being used.
  55  *
  56  * For legacy reasons, the FSFileBackend class allows manually setting the paths of
  57  * containers to ones that do not respect the "domain ID".
  58  *
  59  * In key/value (object) stores, containers are the only hierarchy (the rest is emulated).
  60  * FS-based backends are somewhat more restrictive due to the existence of real
  61  * directory files; a regular file cannot have the same name as a directory. Other
  62  * backends with virtual directories may not have this limitation. Callers should
  63  * store files in such a way that no files and directories are under the same path.
  64  *
  65  * In general, this class allows for callers to access storage through the same
  66  * interface, without regard to the underlying storage system. However, calling code
  67  * must follow certain patterns and be aware of certain things to ensure compatibility:
  68  *   - a) Always call prepare() on the parent directory before trying to put a file there;
  69  *        key/value stores only need the container to exist first, but filesystems need
  70  *        all the parent directories to exist first (prepare() is aware of all this)
  71  *   - b) Always call clean() on a directory when it might become empty to avoid empty
  72  *        directory buildup on filesystems; key/value stores never have empty directories,
  73  *        so doing this helps preserve consistency in both cases
  74  *   - c) Likewise, do not rely on the existence of empty directories for anything;
  75  *        calling directoryExists() on a path that prepare() was previously called on
  76  *        will return false for key/value stores if there are no files under that path
  77  *   - d) Never alter the resulting FSFile returned from getLocalReference(), as it could
  78  *        either be a copy of the source file in /tmp or the original source file itself
  79  *   - e) Use a file layout that results in never attempting to store files over directories
  80  *        or directories over files; key/value stores allow this but filesystems do not
  81  *   - f) Use ASCII file names (e.g. base32, IDs, hashes) to avoid Unicode issues in Windows
  82  *   - g) Do not assume that move operations are atomic (difficult with key/value stores)
  83  *   - h) Do not assume that file stat or read operations always have immediate consistency;
  84  *        various methods have a "latest" flag that should always be used if up-to-date
  85  *        information is required (this trades performance for correctness as needed)
  86  *   - i) Do not assume that directory listings have immediate consistency
  87  *
  88  * Methods of subclasses should avoid throwing exceptions at all costs.
  89  * As a corollary, external dependencies should be kept to a minimum.
  90  *
  91  * @ingroup FileBackend
  92  * @since 1.19
  93  */
  94 abstract class FileBackend implements LoggerAwareInterface {
  95         /** @var string Unique backend name */
  96         protected $name;
  97
  98         /** @var string Unique domain name */
  99         protected $domainId;
 100
 101         /** @var string Read-only explanation message */
 102         protected $readOnly;
 103
 104         /** @var string When to do operations in parallel */
 105         protected $parallelize;
 106
 107         /** @var int How many operations can be done in parallel */
 108         protected $concurrency;
 109
 110         /** @var TempFSFileFactory */
 111         protected $tmpFileFactory;
 112
 113         /** @var LockManager */
 114         protected $lockManager;
 115         /** @var FileJournal */
 116         protected $fileJournal;
 117         /** @var LoggerInterface */
 118         protected $logger;
 119         /** @var callable|null */
 120         protected $profiler;
 121
 122         /** @var callable */
 123         protected $obResetFunc;
 124         /** @var callable */
 125         protected $streamMimeFunc;
 126         /** @var callable */
 127         protected $statusWrapper;
 128
 129         /** Bitfield flags for supported features */
 130         const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
 131         const ATTR_METADATA = 2; // files can be stored with metadata key/values
 132         const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
 133
 134         /**
 135          * Create a new backend instance from configuration.
 136          * This should only be called from within FileBackendGroup.
 137          *
 138          * @param array $config Parameters include:
 139          *   - name : The unique name of this backend.
 140          *      This should consist of alphanumberic, '-', and '_' characters.
 141          *      This name should not be changed after use (e.g. with journaling).
 142          *      Note that the name is *not* used in actual container names.
 143          *   - domainId : Prefix to container names that is unique to this backend.
 144          *      It should only consist of alphanumberic, '-', and '_' characters.
 145          *      This ID is what avoids collisions if multiple logical backends
 146          *      use the same storage system, so this should be set carefully.
 147          *   - lockManager : LockManager object to use for any file locking.
 148          *      If not provided, then no file locking will be enforced.
 149          *   - fileJournal : FileJournal object to use for logging changes to files.
 150          *      If not provided, then change journaling will be disabled.
 151          *   - readOnly : Write operations are disallowed if this is a non-empty string.
 152          *      It should be an explanation for the backend being read-only.
 153          *   - parallelize : When to do file operations in parallel (when possible).
 154          *      Allowed values are "implicit", "explicit" and "off".
 155          *   - concurrency : How many file operations can be done in parallel.
 156          *   - tmpDirectory : Directory to use for temporary files.
 157          *   - tmpFileFactory : Optional TempFSFileFactory object. Only has an effect if tmpDirectory is
 158          *      not set. If both are unset or null, then the backend will try to discover a usable
 159          *      temporary directory.
 160          *   - obResetFunc : alternative callback to clear the output buffer
 161          *   - streamMimeFunc : alternative method to determine the content type from the path
 162          *   - logger : Optional PSR logger object.
 163          *   - profiler : Optional callback that takes a section name argument and returns
 164          *      a ScopedCallback instance that ends the profile section in its destructor.
 165          * @throws InvalidArgumentException
 166          */
 167         public function __construct( array $config ) {
 168                 $this->name = $config['name'];
 169                 $this->domainId = $config['domainId'] // e.g. "my_wiki-en_"
 170                         ?? $config['wikiId']; // b/c alias
 171                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 172                         throw new InvalidArgumentException( "Backend name '{$this->name}' is invalid." );
 173                 } elseif ( !is_string( $this->domainId ) ) {
 174                         throw new InvalidArgumentException(
 175                                 "Backend domain ID not provided for '{$this->name}'." );
 176                 }
 177                 $this->lockManager = $config['lockManager'] ?? new NullLockManager( [] );
 178                 $this->fileJournal = $config['fileJournal']
 179                         ?? FileJournal::factory( [ 'class' => NullFileJournal::class ], $this->name );
 180                 $this->readOnly = isset( $config['readOnly'] )
 181                         ? (string)$config['readOnly']
 182                         : '';
 183                 $this->parallelize = isset( $config['parallelize'] )
 184                         ? (string)$config['parallelize']
 185                         : 'off';
 186                 $this->concurrency = isset( $config['concurrency'] )
 187                         ? (int)$config['concurrency']
 188                         : 50;
 189                 $this->obResetFunc = $config['obResetFunc'] ?? [ $this, 'resetOutputBuffer' ];
 190                 $this->streamMimeFunc = $config['streamMimeFunc'] ?? null;
 191                 $this->statusWrapper = $config['statusWrapper'] ?? null;
 192
 193                 $this->profiler = $config['profiler'] ?? null;
 194                 if ( !is_callable( $this->profiler ) ) {
 195                         $this->profiler = null;
 196                 }
 197                 $this->logger = $config['logger'] ?? new NullLogger();
 198                 $this->statusWrapper = $config['statusWrapper'] ?? null;
 199                 // tmpDirectory gets precedence for backward compatibility
 200                 if ( isset( $config['tmpDirectory'] ) ) {
 201                         $this->tmpFileFactory = new TempFSFileFactory( $config['tmpDirectory'] );
 202                 } else {
 203                         $this->tmpFileFactory = $config['tmpFileFactory'] ?? new TempFSFileFactory();
 204                 }
 205         }
 206
 207         public function setLogger( LoggerInterface $logger ) {
 208                 $this->logger = $logger;
 209         }
 210
 211         /**
 212          * Get the unique backend name.
 213          * We may have multiple different backends of the same type.
 214          * For example, we can have two Swift backends using different proxies.
 215          *
 216          * @return string
 217          */
 218         final public function getName() {
 219                 return $this->name;
 220         }
 221
 222         /**
 223          * Get the domain identifier used for this backend (possibly empty).
 224          *
 225          * @return string
 226          * @since 1.28
 227          */
 228         final public function getDomainId() {
 229                 return $this->domainId;
 230         }
 231
 232         /**
 233          * Alias to getDomainId()
 234          * @return string
 235          * @since 1.20
 236          * @deprecated Since 1.34 Use getDomainId()
 237          */
 238         final public function getWikiId() {
 239                 return $this->getDomainId();
 240         }
 241
 242         /**
 243          * Check if this backend is read-only
 244          *
 245          * @return bool
 246          */
 247         final public function isReadOnly() {
 248                 return ( $this->readOnly != '' );
 249         }
 250
 251         /**
 252          * Get an explanatory message if this backend is read-only
 253          *
 254          * @return string|bool Returns false if the backend is not read-only
 255          */
 256         final public function getReadOnlyReason() {
 257                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 258         }
 259
 260         /**
 261          * Get the a bitfield of extra features supported by the backend medium
 262          *
 263          * @return int Bitfield of FileBackend::ATTR_* flags
 264          * @since 1.23
 265          */
 266         public function getFeatures() {
 267                 return self::ATTR_UNICODE_PATHS;
 268         }
 269
 270         /**
 271          * Check if the backend medium supports a field of extra features
 272          *
 273          * @param int $bitfield Bitfield of FileBackend::ATTR_* flags
 274          * @return bool
 275          * @since 1.23
 276          */
 277         final public function hasFeatures( $bitfield ) {
 278                 return ( $this->getFeatures() & $bitfield ) === $bitfield;
 279         }
 280
 281         /**
 282          * This is the main entry point into the backend for write operations.
 283          * Callers supply an ordered list of operations to perform as a transaction.
 284          * Files will be locked, the stat cache cleared, and then the operations attempted.
 285          * If any serious errors occur, all attempted operations will be rolled back.
 286          *
 287          * $ops is an array of arrays. The outer array holds a list of operations.
 288          * Each inner array is a set of key value pairs that specify an operation.
 289          *
 290          * Supported operations and their parameters. The supported actions are:
 291          *  - create
 292          *  - store
 293          *  - copy
 294          *  - move
 295          *  - delete
 296          *  - describe (since 1.21)
 297          *  - null
 298          *
 299          * FSFile/TempFSFile object support was added in 1.27.
 300          *
 301          * a) Create a new file in storage with the contents of a string
 302          * @code
 303          *     [
 304          *         'op'                  => 'create',
 305          *         'dst'                 => <storage path>,
 306          *         'content'             => <string of new file contents>,
 307          *         'overwrite'           => <boolean>,
 308          *         'overwriteSame'       => <boolean>,
 309          *         'headers'             => <HTTP header name/value map> # since 1.21
 310          *     ]
 311          * @endcode
 312          *
 313          * b) Copy a file system file into storage
 314          * @code
 315          *     [
 316          *         'op'                  => 'store',
 317          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 318          *         'dst'                 => <storage path>,
 319          *         'overwrite'           => <boolean>,
 320          *         'overwriteSame'       => <boolean>,
 321          *         'headers'             => <HTTP header name/value map> # since 1.21
 322          *     ]
 323          * @endcode
 324          *
 325          * c) Copy a file within storage
 326          * @code
 327          *     [
 328          *         'op'                  => 'copy',
 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          * d) Move a file within storage
 339          * @code
 340          *     [
 341          *         'op'                  => 'move',
 342          *         'src'                 => <storage path>,
 343          *         'dst'                 => <storage path>,
 344          *         'overwrite'           => <boolean>,
 345          *         'overwriteSame'       => <boolean>,
 346          *         'ignoreMissingSource' => <boolean>, # since 1.21
 347          *         'headers'             => <HTTP header name/value map> # since 1.21
 348          *     ]
 349          * @endcode
 350          *
 351          * e) Delete a file within storage
 352          * @code
 353          *     [
 354          *         'op'                  => 'delete',
 355          *         'src'                 => <storage path>,
 356          *         'ignoreMissingSource' => <boolean>
 357          *     ]
 358          * @endcode
 359          *
 360          * f) Update metadata for a file within storage
 361          * @code
 362          *     [
 363          *         'op'                  => 'describe',
 364          *         'src'                 => <storage path>,
 365          *         'headers'             => <HTTP header name/value map>
 366          *     ]
 367          * @endcode
 368          *
 369          * g) Do nothing (no-op)
 370          * @code
 371          *     [
 372          *         'op'                  => 'null',
 373          *     ]
 374          * @endcode
 375          *
 376          * Boolean flags for operations (operation-specific):
 377          *   - ignoreMissingSource : The operation will simply succeed and do
 378          *                           nothing if the source file does not exist.
 379          *   - overwrite           : Any destination file will be overwritten.
 380          *   - overwriteSame       : If a file already exists at the destination with the
 381          *                           same contents, then do nothing to the destination file
 382          *                           instead of giving an error. This does not compare headers.
 383          *                           This option is ignored if 'overwrite' is already provided.
 384          *   - headers             : If supplied, the result of merging these headers with any
 385          *                           existing source file headers (replacing conflicting ones)
 386          *                           will be set as the destination file headers. Headers are
 387          *                           deleted if their value is set to the empty string. When a
 388          *                           file has headers they are included in responses to GET and
 389          *                           HEAD requests to the backing store for that file.
 390          *                           Header values should be no larger than 255 bytes, except for
 391          *                           Content-Disposition. The system might ignore or truncate any
 392          *                           headers that are too long to store (exact limits will vary).
 393          *                           Backends that don't support metadata ignore this. (since 1.21)
 394          *
 395          * $opts is an associative of boolean flags, including:
 396          *   - force               : Operation precondition errors no longer trigger an abort.
 397          *                           Any remaining operations are still attempted. Unexpected
 398          *                           failures may still cause remaining operations to be aborted.
 399          *   - nonLocking          : No locks are acquired for the operations.
 400          *                           This can increase performance for non-critical writes.
 401          *                           This has no effect unless the 'force' flag is set.
 402          *   - nonJournaled        : Don't log this operation batch in the file journal.
 403          *                           This limits the ability of recovery scripts.
 404          *   - parallelize         : Try to do operations in parallel when possible.
 405          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 406          *   - preserveCache       : Don't clear the process cache before checking files.
 407          *                           This should only be used if all entries in the process
 408          *                           cache were added after the files were already locked. (since 1.20)
 409          *
 410          * @note Remarks on locking:
 411          * File system paths given to operations should refer to files that are
 412          * already locked or otherwise safe from modification from other processes.
 413          * Normally these files will be new temp files, which should be adequate.
 414          *
 415          * @par Return value:
 416          *
 417          * This returns a Status, which contains all warnings and fatals that occurred
 418          * during the operation. The 'failCount', 'successCount', and 'success' members
 419          * will reflect each operation attempted.
 420          *
 421          * The StatusValue will be "OK" unless:
 422          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 423          *   - b) predicted operation errors occurred and 'force' was not set
 424          *
 425          * @param array $ops List of operations to execute in order
 426          * @param array $opts Batch operation options
 427          * @return StatusValue
 428          */
 429         final public function doOperations( array $ops, array $opts = [] ) {
 430                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 431                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 432                 }
 433                 if ( $ops === [] ) {
 434                         return $this->newStatus(); // nothing to do
 435                 }
 436
 437                 $ops = $this->resolveFSFileObjects( $ops );
 438                 if ( empty( $opts['force'] ) ) { // sanity
 439                         unset( $opts['nonLocking'] );
 440                 }
 441
 442                 /** @noinspection PhpUnusedLocalVariableInspection */
 443                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 444
 445                 return $this->doOperationsInternal( $ops, $opts );
 446         }
 447
 448         /**
 449          * @see FileBackend::doOperations()
 450          * @param array $ops
 451          * @param array $opts
 452          * @return StatusValue
 453          */
 454         abstract protected function doOperationsInternal( array $ops, array $opts );
 455
 456         /**
 457          * Same as doOperations() except it takes a single operation.
 458          * If you are doing a batch of operations that should either
 459          * all succeed or all fail, then use that function instead.
 460          *
 461          * @see FileBackend::doOperations()
 462          *
 463          * @param array $op Operation
 464          * @param array $opts Operation options
 465          * @return StatusValue
 466          */
 467         final public function doOperation( array $op, array $opts = [] ) {
 468                 return $this->doOperations( [ $op ], $opts );
 469         }
 470
 471         /**
 472          * Performs a single create operation.
 473          * This sets $params['op'] to 'create' and passes it to doOperation().
 474          *
 475          * @see FileBackend::doOperation()
 476          *
 477          * @param array $params Operation parameters
 478          * @param array $opts Operation options
 479          * @return StatusValue
 480          */
 481         final public function create( array $params, array $opts = [] ) {
 482                 return $this->doOperation( [ 'op' => 'create' ] + $params, $opts );
 483         }
 484
 485         /**
 486          * Performs a single store operation.
 487          * This sets $params['op'] to 'store' and passes it to doOperation().
 488          *
 489          * @see FileBackend::doOperation()
 490          *
 491          * @param array $params Operation parameters
 492          * @param array $opts Operation options
 493          * @return StatusValue
 494          */
 495         final public function store( array $params, array $opts = [] ) {
 496                 return $this->doOperation( [ 'op' => 'store' ] + $params, $opts );
 497         }
 498
 499         /**
 500          * Performs a single copy operation.
 501          * This sets $params['op'] to 'copy' and passes it to doOperation().
 502          *
 503          * @see FileBackend::doOperation()
 504          *
 505          * @param array $params Operation parameters
 506          * @param array $opts Operation options
 507          * @return StatusValue
 508          */
 509         final public function copy( array $params, array $opts = [] ) {
 510                 return $this->doOperation( [ 'op' => 'copy' ] + $params, $opts );
 511         }
 512
 513         /**
 514          * Performs a single move operation.
 515          * This sets $params['op'] to 'move' and passes it to doOperation().
 516          *
 517          * @see FileBackend::doOperation()
 518          *
 519          * @param array $params Operation parameters
 520          * @param array $opts Operation options
 521          * @return StatusValue
 522          */
 523         final public function move( array $params, array $opts = [] ) {
 524                 return $this->doOperation( [ 'op' => 'move' ] + $params, $opts );
 525         }
 526
 527         /**
 528          * Performs a single delete operation.
 529          * This sets $params['op'] to 'delete' and passes it to doOperation().
 530          *
 531          * @see FileBackend::doOperation()
 532          *
 533          * @param array $params Operation parameters
 534          * @param array $opts Operation options
 535          * @return StatusValue
 536          */
 537         final public function delete( array $params, array $opts = [] ) {
 538                 return $this->doOperation( [ 'op' => 'delete' ] + $params, $opts );
 539         }
 540
 541         /**
 542          * Performs a single describe operation.
 543          * This sets $params['op'] to 'describe' and passes it to doOperation().
 544          *
 545          * @see FileBackend::doOperation()
 546          *
 547          * @param array $params Operation parameters
 548          * @param array $opts Operation options
 549          * @return StatusValue
 550          * @since 1.21
 551          */
 552         final public function describe( array $params, array $opts = [] ) {
 553                 return $this->doOperation( [ 'op' => 'describe' ] + $params, $opts );
 554         }
 555
 556         /**
 557          * Perform a set of independent file operations on some files.
 558          *
 559          * This does no locking, nor journaling, and possibly no stat calls.
 560          * Any destination files that already exist will be overwritten.
 561          * This should *only* be used on non-original files, like cache files.
 562          *
 563          * Supported operations and their parameters:
 564          *  - create
 565          *  - store
 566          *  - copy
 567          *  - move
 568          *  - delete
 569          *  - describe (since 1.21)
 570          *  - null
 571          *
 572          * FSFile/TempFSFile object support was added in 1.27.
 573          *
 574          * a) Create a new file in storage with the contents of a string
 575          * @code
 576          *     [
 577          *         'op'                  => 'create',
 578          *         'dst'                 => <storage path>,
 579          *         'content'             => <string of new file contents>,
 580          *         'headers'             => <HTTP header name/value map> # since 1.21
 581          *     ]
 582          * @endcode
 583          *
 584          * b) Copy a file system file into storage
 585          * @code
 586          *     [
 587          *         'op'                  => 'store',
 588          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 589          *         'dst'                 => <storage path>,
 590          *         'headers'             => <HTTP header name/value map> # since 1.21
 591          *     ]
 592          * @endcode
 593          *
 594          * c) Copy a file within storage
 595          * @code
 596          *     [
 597          *         'op'                  => 'copy',
 598          *         'src'                 => <storage path>,
 599          *         'dst'                 => <storage path>,
 600          *         'ignoreMissingSource' => <boolean>, # since 1.21
 601          *         'headers'             => <HTTP header name/value map> # since 1.21
 602          *     ]
 603          * @endcode
 604          *
 605          * d) Move a file within storage
 606          * @code
 607          *     [
 608          *         'op'                  => 'move',
 609          *         'src'                 => <storage path>,
 610          *         'dst'                 => <storage path>,
 611          *         'ignoreMissingSource' => <boolean>, # since 1.21
 612          *         'headers'             => <HTTP header name/value map> # since 1.21
 613          *     ]
 614          * @endcode
 615          *
 616          * e) Delete a file within storage
 617          * @code
 618          *     [
 619          *         'op'                  => 'delete',
 620          *         'src'                 => <storage path>,
 621          *         'ignoreMissingSource' => <boolean>
 622          *     ]
 623          * @endcode
 624          *
 625          * f) Update metadata for a file within storage
 626          * @code
 627          *     [
 628          *         'op'                  => 'describe',
 629          *         'src'                 => <storage path>,
 630          *         'headers'             => <HTTP header name/value map>
 631          *     ]
 632          * @endcode
 633          *
 634          * g) Do nothing (no-op)
 635          * @code
 636          *     [
 637          *         'op'                  => 'null',
 638          *     ]
 639          * @endcode
 640          *
 641          * @par Boolean flags for operations (operation-specific):
 642          *   - ignoreMissingSource : The operation will simply succeed and do
 643          *                           nothing if the source file does not exist.
 644          *   - headers             : If supplied with a header name/value map, the backend will
 645          *                           reply with these headers when GETs/HEADs of the destination
 646          *                           file are made. Header values should be smaller than 256 bytes.
 647          *                           Content-Disposition headers can be longer, though the system
 648          *                           might ignore or truncate ones that are too long to store.
 649          *                           Existing headers will remain, but these will replace any
 650          *                           conflicting previous headers, and headers will be removed
 651          *                           if they are set to an empty string.
 652          *                           Backends that don't support metadata ignore this. (since 1.21)
 653          *
 654          * $opts is an associative of boolean flags, including:
 655          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 656          *
 657          * @par Return value:
 658          * This returns a Status, which contains all warnings and fatals that occurred
 659          * during the operation. The 'failCount', 'successCount', and 'success' members
 660          * will reflect each operation attempted for the given files. The StatusValue will be
 661          * considered "OK" as long as no fatal errors occurred.
 662          *
 663          * @param array $ops Set of operations to execute
 664          * @param array $opts Batch operation options
 665          * @return StatusValue
 666          * @since 1.20
 667          */
 668         final public function doQuickOperations( array $ops, array $opts = [] ) {
 669                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 670                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 671                 }
 672                 if ( $ops === [] ) {
 673                         return $this->newStatus(); // nothing to do
 674                 }
 675
 676                 $ops = $this->resolveFSFileObjects( $ops );
 677                 foreach ( $ops as &$op ) {
 678                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 679                 }
 680
 681                 /** @noinspection PhpUnusedLocalVariableInspection */
 682                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 683
 684                 return $this->doQuickOperationsInternal( $ops );
 685         }
 686
 687         /**
 688          * @see FileBackend::doQuickOperations()
 689          * @param array $ops
 690          * @return StatusValue
 691          * @since 1.20
 692          */
 693         abstract protected function doQuickOperationsInternal( array $ops );
 694
 695         /**
 696          * Same as doQuickOperations() except it takes a single operation.
 697          * If you are doing a batch of operations, then use that function instead.
 698          *
 699          * @see FileBackend::doQuickOperations()
 700          *
 701          * @param array $op Operation
 702          * @return StatusValue
 703          * @since 1.20
 704          */
 705         final public function doQuickOperation( array $op ) {
 706                 return $this->doQuickOperations( [ $op ] );
 707         }
 708
 709         /**
 710          * Performs a single quick create operation.
 711          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 712          *
 713          * @see FileBackend::doQuickOperation()
 714          *
 715          * @param array $params Operation parameters
 716          * @return StatusValue
 717          * @since 1.20
 718          */
 719         final public function quickCreate( array $params ) {
 720                 return $this->doQuickOperation( [ 'op' => 'create' ] + $params );
 721         }
 722
 723         /**
 724          * Performs a single quick store operation.
 725          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 726          *
 727          * @see FileBackend::doQuickOperation()
 728          *
 729          * @param array $params Operation parameters
 730          * @return StatusValue
 731          * @since 1.20
 732          */
 733         final public function quickStore( array $params ) {
 734                 return $this->doQuickOperation( [ 'op' => 'store' ] + $params );
 735         }
 736
 737         /**
 738          * Performs a single quick copy operation.
 739          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 740          *
 741          * @see FileBackend::doQuickOperation()
 742          *
 743          * @param array $params Operation parameters
 744          * @return StatusValue
 745          * @since 1.20
 746          */
 747         final public function quickCopy( array $params ) {
 748                 return $this->doQuickOperation( [ 'op' => 'copy' ] + $params );
 749         }
 750
 751         /**
 752          * Performs a single quick move operation.
 753          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 754          *
 755          * @see FileBackend::doQuickOperation()
 756          *
 757          * @param array $params Operation parameters
 758          * @return StatusValue
 759          * @since 1.20
 760          */
 761         final public function quickMove( array $params ) {
 762                 return $this->doQuickOperation( [ 'op' => 'move' ] + $params );
 763         }
 764
 765         /**
 766          * Performs a single quick delete operation.
 767          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 768          *
 769          * @see FileBackend::doQuickOperation()
 770          *
 771          * @param array $params Operation parameters
 772          * @return StatusValue
 773          * @since 1.20
 774          */
 775         final public function quickDelete( array $params ) {
 776                 return $this->doQuickOperation( [ 'op' => 'delete' ] + $params );
 777         }
 778
 779         /**
 780          * Performs a single quick describe operation.
 781          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 782          *
 783          * @see FileBackend::doQuickOperation()
 784          *
 785          * @param array $params Operation parameters
 786          * @return StatusValue
 787          * @since 1.21
 788          */
 789         final public function quickDescribe( array $params ) {
 790                 return $this->doQuickOperation( [ 'op' => 'describe' ] + $params );
 791         }
 792
 793         /**
 794          * Concatenate a list of storage files into a single file system file.
 795          * The target path should refer to a file that is already locked or
 796          * otherwise safe from modification from other processes. Normally,
 797          * the file will be a new temp file, which should be adequate.
 798          *
 799          * @param array $params Operation parameters, include:
 800          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 801          *   - dst         : file system path to 0-byte temp file
 802          *   - parallelize : try to do operations in parallel when possible
 803          * @return StatusValue
 804          */
 805         abstract public function concatenate( array $params );
 806
 807         /**
 808          * Prepare a storage directory for usage.
 809          * This will create any required containers and parent directories.
 810          * Backends using key/value stores only need to create the container.
 811          *
 812          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 813          * except they are only applied *if* the directory/container had to be created.
 814          * These flags should always be set for directories that have private files.
 815          * However, setting them is not guaranteed to actually do anything.
 816          * Additional server configuration may be needed to achieve the desired effect.
 817          *
 818          * @param array $params Parameters include:
 819          *   - dir            : storage directory
 820          *   - noAccess       : try to deny file access (since 1.20)
 821          *   - noListing      : try to deny file listing (since 1.20)
 822          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 823          * @return StatusValue
 824          */
 825         final public function prepare( array $params ) {
 826                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 827                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 828                 }
 829                 /** @noinspection PhpUnusedLocalVariableInspection */
 830                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 831                 return $this->doPrepare( $params );
 832         }
 833
 834         /**
 835          * @see FileBackend::prepare()
 836          * @param array $params
 837          * @return StatusValue
 838          */
 839         abstract protected function doPrepare( array $params );
 840
 841         /**
 842          * Take measures to block web access to a storage directory and
 843          * the container it belongs to. FS backends might add .htaccess
 844          * files whereas key/value store backends might revoke container
 845          * access to the storage user representing end-users in web requests.
 846          *
 847          * This is not guaranteed to actually make files or listings publicly hidden.
 848          * Additional server configuration may be needed to achieve the desired effect.
 849          *
 850          * @param array $params Parameters include:
 851          *   - dir            : storage directory
 852          *   - noAccess       : try to deny file access
 853          *   - noListing      : try to deny file listing
 854          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 855          * @return StatusValue
 856          */
 857         final public function secure( array $params ) {
 858                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 859                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 860                 }
 861                 /** @noinspection PhpUnusedLocalVariableInspection */
 862                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 863                 return $this->doSecure( $params );
 864         }
 865
 866         /**
 867          * @see FileBackend::secure()
 868          * @param array $params
 869          * @return StatusValue
 870          */
 871         abstract protected function doSecure( array $params );
 872
 873         /**
 874          * Remove measures to block web access to a storage directory and
 875          * the container it belongs to. FS backends might remove .htaccess
 876          * files whereas key/value store backends might grant container
 877          * access to the storage user representing end-users in web requests.
 878          * This essentially can undo the result of secure() calls.
 879          *
 880          * This is not guaranteed to actually make files or listings publicly viewable.
 881          * Additional server configuration may be needed to achieve the desired effect.
 882          *
 883          * @param array $params Parameters include:
 884          *   - dir            : storage directory
 885          *   - access         : try to allow file access
 886          *   - listing        : try to allow file listing
 887          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 888          * @return StatusValue
 889          * @since 1.20
 890          */
 891         final public function publish( array $params ) {
 892                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 893                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 894                 }
 895                 /** @noinspection PhpUnusedLocalVariableInspection */
 896                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 897                 return $this->doPublish( $params );
 898         }
 899
 900         /**
 901          * @see FileBackend::publish()
 902          * @param array $params
 903          * @return StatusValue
 904          */
 905         abstract protected function doPublish( array $params );
 906
 907         /**
 908          * Delete a storage directory if it is empty.
 909          * Backends using key/value stores may do nothing unless the directory
 910          * is that of an empty container, in which case it will be deleted.
 911          *
 912          * @param array $params Parameters include:
 913          *   - dir            : storage directory
 914          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 915          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 916          * @return StatusValue
 917          */
 918         final public function clean( array $params ) {
 919                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 920                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 921                 }
 922                 /** @noinspection PhpUnusedLocalVariableInspection */
 923                 $scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
 924                 return $this->doClean( $params );
 925         }
 926
 927         /**
 928          * @see FileBackend::clean()
 929          * @param array $params
 930          * @return StatusValue
 931          */
 932         abstract protected function doClean( array $params );
 933
 934         /**
 935          * Check if a file exists at a storage path in the backend.
 936          * This returns false if only a directory exists at the path.
 937          *
 938          * @param array $params Parameters include:
 939          *   - src    : source storage path
 940          *   - latest : use the latest available data
 941          * @return bool|null Returns null on failure
 942          */
 943         abstract public function fileExists( array $params );
 944
 945         /**
 946          * Get the last-modified timestamp of the file at a storage path.
 947          *
 948          * @param array $params Parameters include:
 949          *   - src    : source storage path
 950          *   - latest : use the latest available data
 951          * @return string|bool TS_MW timestamp or false on failure
 952          */
 953         abstract public function getFileTimestamp( array $params );
 954
 955         /**
 956          * Get the contents of a file at a storage path in the backend.
 957          * This should be avoided for potentially large files.
 958          *
 959          * @param array $params Parameters include:
 960          *   - src    : source storage path
 961          *   - latest : use the latest available data
 962          * @return string|bool Returns false on failure
 963          */
 964         final public function getFileContents( array $params ) {
 965                 $contents = $this->getFileContentsMulti(
 966                         [ 'srcs' => [ $params['src'] ] ] + $params );
 967
 968                 return $contents[$params['src']];
 969         }
 970
 971         /**
 972          * Like getFileContents() except it takes an array of storage paths
 973          * and returns a map of storage paths to strings (or null on failure).
 974          * The map keys (paths) are in the same order as the provided list of paths.
 975          *
 976          * @see FileBackend::getFileContents()
 977          *
 978          * @param array $params Parameters include:
 979          *   - srcs        : list of source storage paths
 980          *   - latest      : use the latest available data
 981          *   - parallelize : try to do operations in parallel when possible
 982          * @return array Map of (path name => string or false on failure)
 983          * @since 1.20
 984          */
 985         abstract public function getFileContentsMulti( array $params );
 986
 987         /**
 988          * Get metadata about a file at a storage path in the backend.
 989          * If the file does not exist, then this returns false.
 990          * Otherwise, the result is an associative array that includes:
 991          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 992          *   - metadata : map of file metadata (name => value)
 993          * Metadata keys and headers names will be returned in all lower-case.
 994          * Additional values may be included for internal use only.
 995          *
 996          * Use FileBackend::hasFeatures() to check how well this is supported.
 997          *
 998          * @param array $params
 999          * $params include:
1000          *   - src    : source storage path
1001          *   - latest : use the latest available data
1002          * @return array|bool Returns false on failure
1003          * @since 1.23
1004          */
1005         abstract public function getFileXAttributes( array $params );
1006
1007         /**
1008          * Get the size (bytes) of a file at a storage path in the backend.
1009          *
1010          * @param array $params Parameters include:
1011          *   - src    : source storage path
1012          *   - latest : use the latest available data
1013          * @return int|bool Returns false on failure
1014          */
1015         abstract public function getFileSize( array $params );
1016
1017         /**
1018          * Get quick information about a file at a storage path in the backend.
1019          * If the file does not exist, then this returns false.
1020          * Otherwise, the result is an associative array that includes:
1021          *   - mtime  : the last-modified timestamp (TS_MW)
1022          *   - size   : the file size (bytes)
1023          * Additional values may be included for internal use only.
1024          *
1025          * @param array $params Parameters include:
1026          *   - src    : source storage path
1027          *   - latest : use the latest available data
1028          * @return array|bool|null Returns null on failure
1029          */
1030         abstract public function getFileStat( array $params );
1031
1032         /**
1033          * Get a SHA-1 hash of the file at a storage path in the backend.
1034          *
1035          * @param array $params Parameters include:
1036          *   - src    : source storage path
1037          *   - latest : use the latest available data
1038          * @return string|bool Hash string or false on failure
1039          */
1040         abstract public function getFileSha1Base36( array $params );
1041
1042         /**
1043          * Get the properties of the file at a storage path in the backend.
1044          * This gives the result of FSFile::getProps() on a local copy of the file.
1045          *
1046          * @param array $params Parameters include:
1047          *   - src    : source storage path
1048          *   - latest : use the latest available data
1049          * @return array Returns FSFile::placeholderProps() on failure
1050          */
1051         abstract public function getFileProps( array $params );
1052
1053         /**
1054          * Stream the file at a storage path in the backend.
1055          *
1056          * If the file does not exists, an HTTP 404 error will be given.
1057          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
1058          * will be sent if streaming began, while none will be sent otherwise.
1059          * Implementations should flush the output buffer before sending data.
1060          *
1061          * @param array $params Parameters include:
1062          *   - src      : source storage path
1063          *   - headers  : list of additional HTTP headers to send if the file exists
1064          *   - options  : HTTP request header map with lower case keys (since 1.28). Supports:
1065          *                range             : format is "bytes=(\d*-\d*)"
1066          *                if-modified-since : format is an HTTP date
1067          *   - headless : only include the body (and headers from "headers") (since 1.28)
1068          *   - latest   : use the latest available data
1069          *   - allowOB  : preserve any output buffers (since 1.28)
1070          * @return StatusValue
1071          */
1072         abstract public function streamFile( array $params );
1073
1074         /**
1075          * Returns a file system file, identical to the file at a storage path.
1076          * The file returned is either:
1077          *   - a) A local copy of the file at a storage path in the backend.
1078          *        The temporary copy will have the same extension as the source.
1079          *   - b) An original of the file at a storage path in the backend.
1080          * Temporary files may be purged when the file object falls out of scope.
1081          *
1082          * Write operations should *never* be done on this file as some backends
1083          * may do internal tracking or may be instances of FileBackendMultiWrite.
1084          * In that latter case, there are copies of the file that must stay in sync.
1085          * Additionally, further calls to this function may return the same file.
1086          *
1087          * @param array $params Parameters include:
1088          *   - src    : source storage path
1089          *   - latest : use the latest available data
1090          * @return FSFile|null Returns null on failure
1091          */
1092         final public function getLocalReference( array $params ) {
1093                 $fsFiles = $this->getLocalReferenceMulti(
1094                         [ 'srcs' => [ $params['src'] ] ] + $params );
1095
1096                 return $fsFiles[$params['src']];
1097         }
1098
1099         /**
1100          * Like getLocalReference() except it takes an array of storage paths
1101          * and returns a map of storage paths to FSFile objects (or null on failure).
1102          * The map keys (paths) are in the same order as the provided list of paths.
1103          *
1104          * @see FileBackend::getLocalReference()
1105          *
1106          * @param array $params Parameters include:
1107          *   - srcs        : list of source storage paths
1108          *   - latest      : use the latest available data
1109          *   - parallelize : try to do operations in parallel when possible
1110          * @return array Map of (path name => FSFile or null on failure)
1111          * @since 1.20
1112          */
1113         abstract public function getLocalReferenceMulti( array $params );
1114
1115         /**
1116          * Get a local copy on disk of the file at a storage path in the backend.
1117          * The temporary copy will have the same file extension as the source.
1118          * Temporary files may be purged when the file object falls out of scope.
1119          *
1120          * @param array $params Parameters include:
1121          *   - src    : source storage path
1122          *   - latest : use the latest available data
1123          * @return TempFSFile|null Returns null on failure
1124          */
1125         final public function getLocalCopy( array $params ) {
1126                 $tmpFiles = $this->getLocalCopyMulti(
1127                         [ 'srcs' => [ $params['src'] ] ] + $params );
1128
1129                 return $tmpFiles[$params['src']];
1130         }
1131
1132         /**
1133          * Like getLocalCopy() except it takes an array of storage paths and
1134          * returns a map of storage paths to TempFSFile objects (or null on failure).
1135          * The map keys (paths) are in the same order as the provided list of paths.
1136          *
1137          * @see FileBackend::getLocalCopy()
1138          *
1139          * @param array $params Parameters include:
1140          *   - srcs        : list of source storage paths
1141          *   - latest      : use the latest available data
1142          *   - parallelize : try to do operations in parallel when possible
1143          * @return array Map of (path name => TempFSFile or null on failure)
1144          * @since 1.20
1145          */
1146         abstract public function getLocalCopyMulti( array $params );
1147
1148         /**
1149          * Return an HTTP URL to a given file that requires no authentication to use.
1150          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1151          * This will return null if the backend cannot make an HTTP URL for the file.
1152          *
1153          * This is useful for key/value stores when using scripts that seek around
1154          * large files and those scripts (and the backend) support HTTP Range headers.
1155          * Otherwise, one would need to use getLocalReference(), which involves loading
1156          * the entire file on to local disk.
1157          *
1158          * @param array $params Parameters include:
1159          *   - src : source storage path
1160          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1161          * @return string|null
1162          * @since 1.21
1163          */
1164         abstract public function getFileHttpUrl( array $params );
1165
1166         /**
1167          * Check if a directory exists at a given storage path.
1168          * Backends using key/value stores will check if the path is a
1169          * virtual directory, meaning there are files under the given directory.
1170          *
1171          * Storage backends with eventual consistency might return stale data.
1172          *
1173          * @param array $params Parameters include:
1174          *   - dir : storage directory
1175          * @return bool|null Returns null on failure
1176          * @since 1.20
1177          */
1178         abstract public function directoryExists( array $params );
1179
1180         /**
1181          * Get an iterator to list *all* directories under a storage directory.
1182          * If the directory is of the form "mwstore://backend/container",
1183          * then all directories in the container will be listed.
1184          * If the directory is of form "mwstore://backend/container/dir",
1185          * then all directories directly under that directory will be listed.
1186          * Results will be storage directories relative to the given directory.
1187          *
1188          * Storage backends with eventual consistency might return stale data.
1189          *
1190          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1191          *
1192          * @param array $params Parameters include:
1193          *   - dir     : storage directory
1194          *   - topOnly : only return direct child dirs of the directory
1195          * @return Traversable|array|null Returns null on failure
1196          * @since 1.20
1197          */
1198         abstract public function getDirectoryList( array $params );
1199
1200         /**
1201          * Same as FileBackend::getDirectoryList() except only lists
1202          * directories that are immediately under the given directory.
1203          *
1204          * Storage backends with eventual consistency might return stale data.
1205          *
1206          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1207          *
1208          * @param array $params Parameters include:
1209          *   - dir : storage directory
1210          * @return Traversable|array|null Returns null on failure
1211          * @since 1.20
1212          */
1213         final public function getTopDirectoryList( array $params ) {
1214                 return $this->getDirectoryList( [ 'topOnly' => true ] + $params );
1215         }
1216
1217         /**
1218          * Get an iterator to list *all* stored files under a storage directory.
1219          * If the directory is of the form "mwstore://backend/container",
1220          * then all files in the container will be listed.
1221          * If the directory is of form "mwstore://backend/container/dir",
1222          * then all files under that directory will be listed.
1223          * Results will be storage paths relative to the given directory.
1224          *
1225          * Storage backends with eventual consistency might return stale data.
1226          *
1227          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1228          *
1229          * @param array $params Parameters include:
1230          *   - dir        : storage directory
1231          *   - topOnly    : only return direct child files of the directory (since 1.20)
1232          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1233          * @return Traversable|array|null Returns null on failure
1234          */
1235         abstract public function getFileList( array $params );
1236
1237         /**
1238          * Same as FileBackend::getFileList() except only lists
1239          * files that are immediately under the given directory.
1240          *
1241          * Storage backends with eventual consistency might return stale data.
1242          *
1243          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1244          *
1245          * @param array $params Parameters include:
1246          *   - dir        : storage directory
1247          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1248          * @return Traversable|array|null Returns null on failure
1249          * @since 1.20
1250          */
1251         final public function getTopFileList( array $params ) {
1252                 return $this->getFileList( [ 'topOnly' => true ] + $params );
1253         }
1254
1255         /**
1256          * Preload persistent file stat cache and property cache into in-process cache.
1257          * This should be used when stat calls will be made on a known list of a many files.
1258          *
1259          * @see FileBackend::getFileStat()
1260          *
1261          * @param array $paths Storage paths
1262          */
1263         abstract public function preloadCache( array $paths );
1264
1265         /**
1266          * Invalidate any in-process file stat and property cache.
1267          * If $paths is given, then only the cache for those files will be cleared.
1268          *
1269          * @see FileBackend::getFileStat()
1270          *
1271          * @param array|null $paths Storage paths (optional)
1272          */
1273         abstract public function clearCache( array $paths = null );
1274
1275         /**
1276          * Preload file stat information (concurrently if possible) into in-process cache.
1277          *
1278          * This should be used when stat calls will be made on a known list of a many files.
1279          * This does not make use of the persistent file stat cache.
1280          *
1281          * @see FileBackend::getFileStat()
1282          *
1283          * @param array $params Parameters include:
1284          *   - srcs        : list of source storage paths
1285          *   - latest      : use the latest available data
1286          * @return bool All requests proceeded without I/O errors (since 1.24)
1287          * @since 1.23
1288          */
1289         abstract public function preloadFileStat( array $params );
1290
1291         /**
1292          * Lock the files at the given storage paths in the backend.
1293          * This will either lock all the files or none (on failure).
1294          *
1295          * Callers should consider using getScopedFileLocks() instead.
1296          *
1297          * @param array $paths Storage paths
1298          * @param int $type LockManager::LOCK_* constant
1299          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1300          * @return StatusValue
1301          */
1302         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1303                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1304
1305                 return $this->wrapStatus( $this->lockManager->lock( $paths, $type, $timeout ) );
1306         }
1307
1308         /**
1309          * Unlock the files at the given storage paths in the backend.
1310          *
1311          * @param array $paths Storage paths
1312          * @param int $type LockManager::LOCK_* constant
1313          * @return StatusValue
1314          */
1315         final public function unlockFiles( array $paths, $type ) {
1316                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1317
1318                 return $this->wrapStatus( $this->lockManager->unlock( $paths, $type ) );
1319         }
1320
1321         /**
1322          * Lock the files at the given storage paths in the backend.
1323          * This will either lock all the files or none (on failure).
1324          * On failure, the StatusValue object will be updated with errors.
1325          *
1326          * Once the return value goes out scope, the locks will be released and
1327          * the StatusValue updated. Unlock fatals will not change the StatusValue "OK" value.
1328          *
1329          * @see ScopedLock::factory()
1330          *
1331          * @param array $paths List of storage paths or map of lock types to path lists
1332          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1333          * @param StatusValue $status StatusValue to update on lock/unlock
1334          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1335          * @return ScopedLock|null Returns null on failure
1336          */
1337         final public function getScopedFileLocks(
1338                 array $paths, $type, StatusValue $status, $timeout = 0
1339         ) {
1340                 if ( $type === 'mixed' ) {
1341                         foreach ( $paths as &$typePaths ) {
1342                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1343                         }
1344                 } else {
1345                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1346                 }
1347
1348                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1349         }
1350
1351         /**
1352          * Get an array of scoped locks needed for a batch of file operations.
1353          *
1354          * Normally, FileBackend::doOperations() handles locking, unless
1355          * the 'nonLocking' param is passed in. This function is useful if you
1356          * want the files to be locked for a broader scope than just when the
1357          * files are changing. For example, if you need to update DB metadata,
1358          * you may want to keep the files locked until finished.
1359          *
1360          * @see FileBackend::doOperations()
1361          *
1362          * @param array $ops List of file operations to FileBackend::doOperations()
1363          * @param StatusValue $status StatusValue to update on lock/unlock
1364          * @return ScopedLock|null
1365          * @since 1.20
1366          */
1367         abstract public function getScopedLocksForOps( array $ops, StatusValue $status );
1368
1369         /**
1370          * Get the root storage path of this backend.
1371          * All container paths are "subdirectories" of this path.
1372          *
1373          * @return string Storage path
1374          * @since 1.20
1375          */
1376         final public function getRootStoragePath() {
1377                 return "mwstore://{$this->name}";
1378         }
1379
1380         /**
1381          * Get the storage path for the given container for this backend
1382          *
1383          * @param string $container Container name
1384          * @return string Storage path
1385          * @since 1.21
1386          */
1387         final public function getContainerStoragePath( $container ) {
1388                 return $this->getRootStoragePath() . "/{$container}";
1389         }
1390
1391         /**
1392          * Get the file journal object for this backend
1393          *
1394          * @return FileJournal
1395          */
1396         final public function getJournal() {
1397                 return $this->fileJournal;
1398         }
1399
1400         /**
1401          * Convert FSFile 'src' paths to string paths (with an 'srcRef' field set to the FSFile)
1402          *
1403          * The 'srcRef' field keeps any TempFSFile objects in scope for the backend to have it
1404          * around as long it needs (which may vary greatly depending on configuration)
1405          *
1406          * @param array $ops File operation batch for FileBaclend::doOperations()
1407          * @return array File operation batch
1408          */
1409         protected function resolveFSFileObjects( array $ops ) {
1410                 foreach ( $ops as &$op ) {
1411                         $src = $op['src'] ?? null;
1412                         if ( $src instanceof FSFile ) {
1413                                 $op['srcRef'] = $src;
1414                                 $op['src'] = $src->getPath();
1415                         }
1416                 }
1417                 unset( $op );
1418
1419                 return $ops;
1420         }
1421
1422         /**
1423          * Check if a given path is a "mwstore://" path.
1424          * This does not do any further validation or any existence checks.
1425          *
1426          * @param string $path
1427          * @return bool
1428          */
1429         final public static function isStoragePath( $path ) {
1430                 return ( strpos( $path, 'mwstore://' ) === 0 );
1431         }
1432
1433         /**
1434          * Split a storage path into a backend name, a container name,
1435          * and a relative file path. The relative path may be the empty string.
1436          * This does not do any path normalization or traversal checks.
1437          *
1438          * @param string $storagePath
1439          * @return array (backend, container, rel object) or (null, null, null)
1440          */
1441         final public static function splitStoragePath( $storagePath ) {
1442                 if ( self::isStoragePath( $storagePath ) ) {
1443                         // Remove the "mwstore://" prefix and split the path
1444                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1445                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1446                                 if ( count( $parts ) == 3 ) {
1447                                         return $parts; // e.g. "backend/container/path"
1448                                 } else {
1449                                         return [ $parts[0], $parts[1], '' ]; // e.g. "backend/container"
1450                                 }
1451                         }
1452                 }
1453
1454                 return [ null, null, null ];
1455         }
1456
1457         /**
1458          * Normalize a storage path by cleaning up directory separators.
1459          * Returns null if the path is not of the format of a valid storage path.
1460          *
1461          * @param string $storagePath
1462          * @return string|null
1463          */
1464         final public static function normalizeStoragePath( $storagePath ) {
1465                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1466                 if ( $relPath !== null ) { // must be for this backend
1467                         $relPath = self::normalizeContainerPath( $relPath );
1468                         if ( $relPath !== null ) {
1469                                 return ( $relPath != '' )
1470                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1471                                         : "mwstore://{$backend}/{$container}";
1472                         }
1473                 }
1474
1475                 return null;
1476         }
1477
1478         /**
1479          * Get the parent storage directory of a storage path.
1480          * This returns a path like "mwstore://backend/container",
1481          * "mwstore://backend/container/...", or null if there is no parent.
1482          *
1483          * @param string $storagePath
1484          * @return string|null
1485          */
1486         final public static function parentStoragePath( $storagePath ) {
1487                 $storagePath = dirname( $storagePath );
1488                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1489
1490                 return ( $rel === null ) ? null : $storagePath;
1491         }
1492
1493         /**
1494          * Get the final extension from a storage or FS path
1495          *
1496          * @param string $path
1497          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1498          * @return string
1499          */
1500         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1501                 $i = strrpos( $path, '.' );
1502                 $ext = $i ? substr( $path, $i + 1 ) : '';
1503
1504                 if ( $case === 'lowercase' ) {
1505                         $ext = strtolower( $ext );
1506                 } elseif ( $case === 'uppercase' ) {
1507                         $ext = strtoupper( $ext );
1508                 }
1509
1510                 return $ext;
1511         }
1512
1513         /**
1514          * Check if a relative path has no directory traversals
1515          *
1516          * @param string $path
1517          * @return bool
1518          * @since 1.20
1519          */
1520         final public static function isPathTraversalFree( $path ) {
1521                 return ( self::normalizeContainerPath( $path ) !== null );
1522         }
1523
1524         /**
1525          * Build a Content-Disposition header value per RFC 6266.
1526          *
1527          * @param string $type One of (attachment, inline)
1528          * @param string $filename Suggested file name (should not contain slashes)
1529          * @throws FileBackendError
1530          * @return string
1531          * @since 1.20
1532          */
1533         final public static function makeContentDisposition( $type, $filename = '' ) {
1534                 $parts = [];
1535
1536                 $type = strtolower( $type );
1537                 if ( !in_array( $type, [ 'inline', 'attachment' ] ) ) {
1538                         throw new InvalidArgumentException( "Invalid Content-Disposition type '$type'." );
1539                 }
1540                 $parts[] = $type;
1541
1542                 if ( strlen( $filename ) ) {
1543                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1544                 }
1545
1546                 return implode( ';', $parts );
1547         }
1548
1549         /**
1550          * Validate and normalize a relative storage path.
1551          * Null is returned if the path involves directory traversal.
1552          * Traversal is insecure for FS backends and broken for others.
1553          *
1554          * This uses the same traversal protection as Title::secureAndSplit().
1555          *
1556          * @param string $path Storage path relative to a container
1557          * @return string|null
1558          */
1559         final protected static function normalizeContainerPath( $path ) {
1560                 // Normalize directory separators
1561                 $path = strtr( $path, '\\', '/' );
1562                 // Collapse any consecutive directory separators
1563                 $path = preg_replace( '![/]{2,}!', '/', $path );
1564                 // Remove any leading directory separator
1565                 $path = ltrim( $path, '/' );
1566                 // Use the same traversal protection as Title::secureAndSplit()
1567                 if ( strpos( $path, '.' ) !== false ) {
1568                         if (
1569                                 $path === '.' ||
1570                                 $path === '..' ||
1571                                 strpos( $path, './' ) === 0 ||
1572                                 strpos( $path, '../' ) === 0 ||
1573                                 strpos( $path, '/./' ) !== false ||
1574                                 strpos( $path, '/../' ) !== false
1575                         ) {
1576                                 return null;
1577                         }
1578                 }
1579
1580                 return $path;
1581         }
1582
1583         /**
1584          * Yields the result of the status wrapper callback on either:
1585          *   - StatusValue::newGood() if this method is called without parameters
1586          *   - StatusValue::newFatal() with all parameters to this method if passed in
1587          *
1588          * @param string ...$args
1589          * @return StatusValue
1590          */
1591         final protected function newStatus( ...$args ) {
1592                 if ( count( $args ) ) {
1593                         $sv = StatusValue::newFatal( ...$args );
1594                 } else {
1595                         $sv = StatusValue::newGood();
1596                 }
1597
1598                 return $this->wrapStatus( $sv );
1599         }
1600
1601         /**
1602          * @param StatusValue $sv
1603          * @return StatusValue Modified status or StatusValue subclass
1604          */
1605         final protected function wrapStatus( StatusValue $sv ) {
1606                 return $this->statusWrapper ? call_user_func( $this->statusWrapper, $sv ) : $sv;
1607         }
1608
1609         /**
1610          * @param string $section
1611          * @return ScopedCallback|null
1612          */
1613         protected function scopedProfileSection( $section ) {
1614                 return $this->profiler ? ( $this->profiler )( $section ) : null;
1615         }
1616
1617         protected function resetOutputBuffer() {
1618                 while ( ob_get_status() ) {
1619                         if ( !ob_end_clean() ) {
1620                                 // Could not remove output buffer handler; abort now
1621                                 // to avoid getting in some kind of infinite loop.
1622                                 break;
1623                         }
1624                 }
1625         }
1626 }