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  * @author Aaron Schulz
  30  */
  31 use Psr\Log\LoggerAwareInterface;
  32 use Psr\Log\LoggerInterface;
  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 $statusWrapper;
 122
 123         /** Bitfield flags for supported features */
 124         const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
 125         const ATTR_METADATA = 2; // files can be stored with metadata key/values
 126         const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
 127
 128         /**
 129          * Create a new backend instance from configuration.
 130          * This should only be called from within FileBackendGroup.
 131          *
 132          * @param array $config Parameters include:
 133          *   - name        : The unique name of this backend.
 134          *                   This should consist of alphanumberic, '-', and '_' characters.
 135          *                   This name should not be changed after use (e.g. with journaling).
 136          *                   Note that the name is *not* used in actual container names.
 137          *   - domainId    : Prefix to container names that is unique to this backend.
 138          *                   It should only consist of alphanumberic, '-', and '_' characters.
 139          *                   This ID is what avoids collisions if multiple logical backends
 140          *                   use the same storage system, so this should be set carefully.
 141          *   - lockManager : LockManager object to use for any file locking.
 142          *                   If not provided, then no file locking will be enforced.
 143          *   - fileJournal : FileJournal object to use for logging changes to files.
 144          *                   If not provided, then change journaling will be disabled.
 145          *   - readOnly    : Write operations are disallowed if this is a non-empty string.
 146          *                   It should be an explanation for the backend being read-only.
 147          *   - parallelize : When to do file operations in parallel (when possible).
 148          *                   Allowed values are "implicit", "explicit" and "off".
 149          *   - concurrency : How many file operations can be done in parallel.
 150          *   - tmpDirectory : Directory to use for temporary files. If this is not set or null,
 151          *                    then the backend will try to discover a usable temporary directory.
 152          *   - logger      : Optional PSR logger object.
 153          *   - profiler    : Optional class name or object With profileIn/profileOut methods.
 154          * @throws InvalidArgumentException
 155          */
 156         public function __construct( array $config ) {
 157                 $this->name = $config['name'];
 158                 $this->domainId = isset( $config['domainId'] )
 159                         ? $config['domainId'] // e.g. "my_wiki-en_"
 160                         : $config['wikiId']; // b/c alias
 161                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 162                         throw new InvalidArgumentException( "Backend name '{$this->name}' is invalid." );
 163                 } elseif ( !is_string( $this->domainId ) ) {
 164                         throw new InvalidArgumentException(
 165                                 "Backend domain ID not provided for '{$this->name}'." );
 166                 }
 167                 $this->lockManager = isset( $config['lockManager'] )
 168                         ? $config['lockManager']
 169                         : new NullLockManager( [] );
 170                 $this->fileJournal = isset( $config['fileJournal'] )
 171                         ? $config['fileJournal']
 172                         : FileJournal::factory( [ 'class' => 'NullFileJournal' ], $this->name );
 173                 $this->readOnly = isset( $config['readOnly'] )
 174                         ? (string)$config['readOnly']
 175                         : '';
 176                 $this->parallelize = isset( $config['parallelize'] )
 177                         ? (string)$config['parallelize']
 178                         : 'off';
 179                 $this->concurrency = isset( $config['concurrency'] )
 180                         ? (int)$config['concurrency']
 181                         : 50;
 182                 $this->profiler = isset( $params['profiler'] ) ? $params['profiler'] : null;
 183                 $this->logger = isset( $config['logger'] ) ? $config['logger'] : new \Psr\Log\NullLogger();
 184                 $this->statusWrapper = isset( $config['statusWrapper'] ) ? $config['statusWrapper'] : null;
 185                 $this->tmpDirectory = isset( $config['tmpDirectory'] ) ? $config['tmpDirectory'] : null;
 186         }
 187
 188         public function setLogger( LoggerInterface $logger ) {
 189                 $this->logger = $logger;
 190         }
 191
 192         /**
 193          * Get the unique backend name.
 194          * We may have multiple different backends of the same type.
 195          * For example, we can have two Swift backends using different proxies.
 196          *
 197          * @return string
 198          */
 199         final public function getName() {
 200                 return $this->name;
 201         }
 202
 203         /**
 204          * Get the domain identifier used for this backend (possibly empty).
 205          *
 206          * @return string
 207          * @since 1.28
 208          */
 209         final public function getDomainId() {
 210                 return $this->domainId;
 211         }
 212
 213         /**
 214          * Alias to getDomainId()
 215          * @return string
 216          * @since 1.20
 217          */
 218         final public function getWikiId() {
 219                 return $this->getDomainId();
 220         }
 221
 222         /**
 223          * Check if this backend is read-only
 224          *
 225          * @return bool
 226          */
 227         final public function isReadOnly() {
 228                 return ( $this->readOnly != '' );
 229         }
 230
 231         /**
 232          * Get an explanatory message if this backend is read-only
 233          *
 234          * @return string|bool Returns false if the backend is not read-only
 235          */
 236         final public function getReadOnlyReason() {
 237                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 238         }
 239
 240         /**
 241          * Get the a bitfield of extra features supported by the backend medium
 242          *
 243          * @return int Bitfield of FileBackend::ATTR_* flags
 244          * @since 1.23
 245          */
 246         public function getFeatures() {
 247                 return self::ATTR_UNICODE_PATHS;
 248         }
 249
 250         /**
 251          * Check if the backend medium supports a field of extra features
 252          *
 253          * @param int $bitfield Bitfield of FileBackend::ATTR_* flags
 254          * @return bool
 255          * @since 1.23
 256          */
 257         final public function hasFeatures( $bitfield ) {
 258                 return ( $this->getFeatures() & $bitfield ) === $bitfield;
 259         }
 260
 261         /**
 262          * This is the main entry point into the backend for write operations.
 263          * Callers supply an ordered list of operations to perform as a transaction.
 264          * Files will be locked, the stat cache cleared, and then the operations attempted.
 265          * If any serious errors occur, all attempted operations will be rolled back.
 266          *
 267          * $ops is an array of arrays. The outer array holds a list of operations.
 268          * Each inner array is a set of key value pairs that specify an operation.
 269          *
 270          * Supported operations and their parameters. The supported actions are:
 271          *  - create
 272          *  - store
 273          *  - copy
 274          *  - move
 275          *  - delete
 276          *  - describe (since 1.21)
 277          *  - null
 278          *
 279          * FSFile/TempFSFile object support was added in 1.27.
 280          *
 281          * a) Create a new file in storage with the contents of a string
 282          * @code
 283          *     [
 284          *         'op'                  => 'create',
 285          *         'dst'                 => <storage path>,
 286          *         'content'             => <string of new file contents>,
 287          *         'overwrite'           => <boolean>,
 288          *         'overwriteSame'       => <boolean>,
 289          *         'headers'             => <HTTP header name/value map> # since 1.21
 290          *     ]
 291          * @endcode
 292          *
 293          * b) Copy a file system file into storage
 294          * @code
 295          *     [
 296          *         'op'                  => 'store',
 297          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 298          *         'dst'                 => <storage path>,
 299          *         'overwrite'           => <boolean>,
 300          *         'overwriteSame'       => <boolean>,
 301          *         'headers'             => <HTTP header name/value map> # since 1.21
 302          *     ]
 303          * @endcode
 304          *
 305          * c) Copy a file within storage
 306          * @code
 307          *     [
 308          *         'op'                  => 'copy',
 309          *         'src'                 => <storage path>,
 310          *         'dst'                 => <storage path>,
 311          *         'overwrite'           => <boolean>,
 312          *         'overwriteSame'       => <boolean>,
 313          *         'ignoreMissingSource' => <boolean>, # since 1.21
 314          *         'headers'             => <HTTP header name/value map> # since 1.21
 315          *     ]
 316          * @endcode
 317          *
 318          * d) Move a file within storage
 319          * @code
 320          *     [
 321          *         'op'                  => 'move',
 322          *         'src'                 => <storage path>,
 323          *         'dst'                 => <storage path>,
 324          *         'overwrite'           => <boolean>,
 325          *         'overwriteSame'       => <boolean>,
 326          *         'ignoreMissingSource' => <boolean>, # since 1.21
 327          *         'headers'             => <HTTP header name/value map> # since 1.21
 328          *     ]
 329          * @endcode
 330          *
 331          * e) Delete a file within storage
 332          * @code
 333          *     [
 334          *         'op'                  => 'delete',
 335          *         'src'                 => <storage path>,
 336          *         'ignoreMissingSource' => <boolean>
 337          *     ]
 338          * @endcode
 339          *
 340          * f) Update metadata for a file within storage
 341          * @code
 342          *     [
 343          *         'op'                  => 'describe',
 344          *         'src'                 => <storage path>,
 345          *         'headers'             => <HTTP header name/value map>
 346          *     ]
 347          * @endcode
 348          *
 349          * g) Do nothing (no-op)
 350          * @code
 351          *     [
 352          *         'op'                  => 'null',
 353          *     ]
 354          * @endcode
 355          *
 356          * Boolean flags for operations (operation-specific):
 357          *   - ignoreMissingSource : The operation will simply succeed and do
 358          *                           nothing if the source file does not exist.
 359          *   - overwrite           : Any destination file will be overwritten.
 360          *   - overwriteSame       : If a file already exists at the destination with the
 361          *                           same contents, then do nothing to the destination file
 362          *                           instead of giving an error. This does not compare headers.
 363          *                           This option is ignored if 'overwrite' is already provided.
 364          *   - headers             : If supplied, the result of merging these headers with any
 365          *                           existing source file headers (replacing conflicting ones)
 366          *                           will be set as the destination file headers. Headers are
 367          *                           deleted if their value is set to the empty string. When a
 368          *                           file has headers they are included in responses to GET and
 369          *                           HEAD requests to the backing store for that file.
 370          *                           Header values should be no larger than 255 bytes, except for
 371          *                           Content-Disposition. The system might ignore or truncate any
 372          *                           headers that are too long to store (exact limits will vary).
 373          *                           Backends that don't support metadata ignore this. (since 1.21)
 374          *
 375          * $opts is an associative of boolean flags, including:
 376          *   - force               : Operation precondition errors no longer trigger an abort.
 377          *                           Any remaining operations are still attempted. Unexpected
 378          *                           failures may still cause remaining operations to be aborted.
 379          *   - nonLocking          : No locks are acquired for the operations.
 380          *                           This can increase performance for non-critical writes.
 381          *                           This has no effect unless the 'force' flag is set.
 382          *   - nonJournaled        : Don't log this operation batch in the file journal.
 383          *                           This limits the ability of recovery scripts.
 384          *   - parallelize         : Try to do operations in parallel when possible.
 385          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 386          *   - preserveCache       : Don't clear the process cache before checking files.
 387          *                           This should only be used if all entries in the process
 388          *                           cache were added after the files were already locked. (since 1.20)
 389          *
 390          * @remarks Remarks on locking:
 391          * File system paths given to operations should refer to files that are
 392          * already locked or otherwise safe from modification from other processes.
 393          * Normally these files will be new temp files, which should be adequate.
 394          *
 395          * @par Return value:
 396          *
 397          * This returns a Status, which contains all warnings and fatals that occurred
 398          * during the operation. The 'failCount', 'successCount', and 'success' members
 399          * will reflect each operation attempted.
 400          *
 401          * The StatusValue will be "OK" unless:
 402          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 403          *   - b) significant operation errors occurred and 'force' was not set
 404          *
 405          * @param array $ops List of operations to execute in order
 406          * @param array $opts Batch operation options
 407          * @return StatusValue
 408          */
 409         final public function doOperations( array $ops, array $opts = [] ) {
 410                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 411                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 412                 }
 413                 if ( !count( $ops ) ) {
 414                         return $this->newStatus(); // nothing to do
 415                 }
 416
 417                 $ops = $this->resolveFSFileObjects( $ops );
 418                 if ( empty( $opts['force'] ) ) { // sanity
 419                         unset( $opts['nonLocking'] );
 420                 }
 421
 422                 /** @noinspection PhpUnusedLocalVariableInspection */
 423                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 424
 425                 return $this->doOperationsInternal( $ops, $opts );
 426         }
 427
 428         /**
 429          * @see FileBackend::doOperations()
 430          * @param array $ops
 431          * @param array $opts
 432          */
 433         abstract protected function doOperationsInternal( array $ops, array $opts );
 434
 435         /**
 436          * Same as doOperations() except it takes a single operation.
 437          * If you are doing a batch of operations that should either
 438          * all succeed or all fail, then use that function instead.
 439          *
 440          * @see FileBackend::doOperations()
 441          *
 442          * @param array $op Operation
 443          * @param array $opts Operation options
 444          * @return StatusValue
 445          */
 446         final public function doOperation( array $op, array $opts = [] ) {
 447                 return $this->doOperations( [ $op ], $opts );
 448         }
 449
 450         /**
 451          * Performs a single create operation.
 452          * This sets $params['op'] to 'create' and passes it to doOperation().
 453          *
 454          * @see FileBackend::doOperation()
 455          *
 456          * @param array $params Operation parameters
 457          * @param array $opts Operation options
 458          * @return StatusValue
 459          */
 460         final public function create( array $params, array $opts = [] ) {
 461                 return $this->doOperation( [ 'op' => 'create' ] + $params, $opts );
 462         }
 463
 464         /**
 465          * Performs a single store operation.
 466          * This sets $params['op'] to 'store' and passes it to doOperation().
 467          *
 468          * @see FileBackend::doOperation()
 469          *
 470          * @param array $params Operation parameters
 471          * @param array $opts Operation options
 472          * @return StatusValue
 473          */
 474         final public function store( array $params, array $opts = [] ) {
 475                 return $this->doOperation( [ 'op' => 'store' ] + $params, $opts );
 476         }
 477
 478         /**
 479          * Performs a single copy operation.
 480          * This sets $params['op'] to 'copy' and passes it to doOperation().
 481          *
 482          * @see FileBackend::doOperation()
 483          *
 484          * @param array $params Operation parameters
 485          * @param array $opts Operation options
 486          * @return StatusValue
 487          */
 488         final public function copy( array $params, array $opts = [] ) {
 489                 return $this->doOperation( [ 'op' => 'copy' ] + $params, $opts );
 490         }
 491
 492         /**
 493          * Performs a single move operation.
 494          * This sets $params['op'] to 'move' and passes it to doOperation().
 495          *
 496          * @see FileBackend::doOperation()
 497          *
 498          * @param array $params Operation parameters
 499          * @param array $opts Operation options
 500          * @return StatusValue
 501          */
 502         final public function move( array $params, array $opts = [] ) {
 503                 return $this->doOperation( [ 'op' => 'move' ] + $params, $opts );
 504         }
 505
 506         /**
 507          * Performs a single delete operation.
 508          * This sets $params['op'] to 'delete' and passes it to doOperation().
 509          *
 510          * @see FileBackend::doOperation()
 511          *
 512          * @param array $params Operation parameters
 513          * @param array $opts Operation options
 514          * @return StatusValue
 515          */
 516         final public function delete( array $params, array $opts = [] ) {
 517                 return $this->doOperation( [ 'op' => 'delete' ] + $params, $opts );
 518         }
 519
 520         /**
 521          * Performs a single describe operation.
 522          * This sets $params['op'] to 'describe' and passes it to doOperation().
 523          *
 524          * @see FileBackend::doOperation()
 525          *
 526          * @param array $params Operation parameters
 527          * @param array $opts Operation options
 528          * @return StatusValue
 529          * @since 1.21
 530          */
 531         final public function describe( array $params, array $opts = [] ) {
 532                 return $this->doOperation( [ 'op' => 'describe' ] + $params, $opts );
 533         }
 534
 535         /**
 536          * Perform a set of independent file operations on some files.
 537          *
 538          * This does no locking, nor journaling, and possibly no stat calls.
 539          * Any destination files that already exist will be overwritten.
 540          * This should *only* be used on non-original files, like cache files.
 541          *
 542          * Supported operations and their parameters:
 543          *  - create
 544          *  - store
 545          *  - copy
 546          *  - move
 547          *  - delete
 548          *  - describe (since 1.21)
 549          *  - null
 550          *
 551          * FSFile/TempFSFile object support was added in 1.27.
 552          *
 553          * a) Create a new file in storage with the contents of a string
 554          * @code
 555          *     [
 556          *         'op'                  => 'create',
 557          *         'dst'                 => <storage path>,
 558          *         'content'             => <string of new file contents>,
 559          *         'headers'             => <HTTP header name/value map> # since 1.21
 560          *     ]
 561          * @endcode
 562          *
 563          * b) Copy a file system file into storage
 564          * @code
 565          *     [
 566          *         'op'                  => 'store',
 567          *         'src'                 => <file system path, FSFile, or TempFSFile>,
 568          *         'dst'                 => <storage path>,
 569          *         'headers'             => <HTTP header name/value map> # since 1.21
 570          *     ]
 571          * @endcode
 572          *
 573          * c) Copy a file within storage
 574          * @code
 575          *     [
 576          *         'op'                  => 'copy',
 577          *         'src'                 => <storage path>,
 578          *         'dst'                 => <storage path>,
 579          *         'ignoreMissingSource' => <boolean>, # since 1.21
 580          *         'headers'             => <HTTP header name/value map> # since 1.21
 581          *     ]
 582          * @endcode
 583          *
 584          * d) Move a file within storage
 585          * @code
 586          *     [
 587          *         'op'                  => 'move',
 588          *         'src'                 => <storage path>,
 589          *         'dst'                 => <storage path>,
 590          *         'ignoreMissingSource' => <boolean>, # since 1.21
 591          *         'headers'             => <HTTP header name/value map> # since 1.21
 592          *     ]
 593          * @endcode
 594          *
 595          * e) Delete a file within storage
 596          * @code
 597          *     [
 598          *         'op'                  => 'delete',
 599          *         'src'                 => <storage path>,
 600          *         'ignoreMissingSource' => <boolean>
 601          *     ]
 602          * @endcode
 603          *
 604          * f) Update metadata for a file within storage
 605          * @code
 606          *     [
 607          *         'op'                  => 'describe',
 608          *         'src'                 => <storage path>,
 609          *         'headers'             => <HTTP header name/value map>
 610          *     ]
 611          * @endcode
 612          *
 613          * g) Do nothing (no-op)
 614          * @code
 615          *     [
 616          *         'op'                  => 'null',
 617          *     ]
 618          * @endcode
 619          *
 620          * @par Boolean flags for operations (operation-specific):
 621          *   - ignoreMissingSource : The operation will simply succeed and do
 622          *                           nothing if the source file does not exist.
 623          *   - headers             : If supplied with a header name/value map, the backend will
 624          *                           reply with these headers when GETs/HEADs of the destination
 625          *                           file are made. Header values should be smaller than 256 bytes.
 626          *                           Content-Disposition headers can be longer, though the system
 627          *                           might ignore or truncate ones that are too long to store.
 628          *                           Existing headers will remain, but these will replace any
 629          *                           conflicting previous headers, and headers will be removed
 630          *                           if they are set to an empty string.
 631          *                           Backends that don't support metadata ignore this. (since 1.21)
 632          *
 633          * $opts is an associative of boolean flags, including:
 634          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 635          *
 636          * @par Return value:
 637          * This returns a Status, which contains all warnings and fatals that occurred
 638          * during the operation. The 'failCount', 'successCount', and 'success' members
 639          * will reflect each operation attempted for the given files. The StatusValue will be
 640          * considered "OK" as long as no fatal errors occurred.
 641          *
 642          * @param array $ops Set of operations to execute
 643          * @param array $opts Batch operation options
 644          * @return StatusValue
 645          * @since 1.20
 646          */
 647         final public function doQuickOperations( array $ops, array $opts = [] ) {
 648                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 649                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 650                 }
 651                 if ( !count( $ops ) ) {
 652                         return $this->newStatus(); // nothing to do
 653                 }
 654
 655                 $ops = $this->resolveFSFileObjects( $ops );
 656                 foreach ( $ops as &$op ) {
 657                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 658                 }
 659
 660                 /** @noinspection PhpUnusedLocalVariableInspection */
 661                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 662
 663                 return $this->doQuickOperationsInternal( $ops );
 664         }
 665
 666         /**
 667          * @see FileBackend::doQuickOperations()
 668          * @param array $ops
 669          * @since 1.20
 670          */
 671         abstract protected function doQuickOperationsInternal( array $ops );
 672
 673         /**
 674          * Same as doQuickOperations() except it takes a single operation.
 675          * If you are doing a batch of operations, then use that function instead.
 676          *
 677          * @see FileBackend::doQuickOperations()
 678          *
 679          * @param array $op Operation
 680          * @return StatusValue
 681          * @since 1.20
 682          */
 683         final public function doQuickOperation( array $op ) {
 684                 return $this->doQuickOperations( [ $op ] );
 685         }
 686
 687         /**
 688          * Performs a single quick create operation.
 689          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 690          *
 691          * @see FileBackend::doQuickOperation()
 692          *
 693          * @param array $params Operation parameters
 694          * @return StatusValue
 695          * @since 1.20
 696          */
 697         final public function quickCreate( array $params ) {
 698                 return $this->doQuickOperation( [ 'op' => 'create' ] + $params );
 699         }
 700
 701         /**
 702          * Performs a single quick store operation.
 703          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 704          *
 705          * @see FileBackend::doQuickOperation()
 706          *
 707          * @param array $params Operation parameters
 708          * @return StatusValue
 709          * @since 1.20
 710          */
 711         final public function quickStore( array $params ) {
 712                 return $this->doQuickOperation( [ 'op' => 'store' ] + $params );
 713         }
 714
 715         /**
 716          * Performs a single quick copy operation.
 717          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 718          *
 719          * @see FileBackend::doQuickOperation()
 720          *
 721          * @param array $params Operation parameters
 722          * @return StatusValue
 723          * @since 1.20
 724          */
 725         final public function quickCopy( array $params ) {
 726                 return $this->doQuickOperation( [ 'op' => 'copy' ] + $params );
 727         }
 728
 729         /**
 730          * Performs a single quick move operation.
 731          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 732          *
 733          * @see FileBackend::doQuickOperation()
 734          *
 735          * @param array $params Operation parameters
 736          * @return StatusValue
 737          * @since 1.20
 738          */
 739         final public function quickMove( array $params ) {
 740                 return $this->doQuickOperation( [ 'op' => 'move' ] + $params );
 741         }
 742
 743         /**
 744          * Performs a single quick delete operation.
 745          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 746          *
 747          * @see FileBackend::doQuickOperation()
 748          *
 749          * @param array $params Operation parameters
 750          * @return StatusValue
 751          * @since 1.20
 752          */
 753         final public function quickDelete( array $params ) {
 754                 return $this->doQuickOperation( [ 'op' => 'delete' ] + $params );
 755         }
 756
 757         /**
 758          * Performs a single quick describe operation.
 759          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 760          *
 761          * @see FileBackend::doQuickOperation()
 762          *
 763          * @param array $params Operation parameters
 764          * @return StatusValue
 765          * @since 1.21
 766          */
 767         final public function quickDescribe( array $params ) {
 768                 return $this->doQuickOperation( [ 'op' => 'describe' ] + $params );
 769         }
 770
 771         /**
 772          * Concatenate a list of storage files into a single file system file.
 773          * The target path should refer to a file that is already locked or
 774          * otherwise safe from modification from other processes. Normally,
 775          * the file will be a new temp file, which should be adequate.
 776          *
 777          * @param array $params Operation parameters, include:
 778          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 779          *   - dst         : file system path to 0-byte temp file
 780          *   - parallelize : try to do operations in parallel when possible
 781          * @return StatusValue
 782          */
 783         abstract public function concatenate( array $params );
 784
 785         /**
 786          * Prepare a storage directory for usage.
 787          * This will create any required containers and parent directories.
 788          * Backends using key/value stores only need to create the container.
 789          *
 790          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 791          * except they are only applied *if* the directory/container had to be created.
 792          * These flags should always be set for directories that have private files.
 793          * However, setting them is not guaranteed to actually do anything.
 794          * Additional server configuration may be needed to achieve the desired effect.
 795          *
 796          * @param array $params Parameters include:
 797          *   - dir            : storage directory
 798          *   - noAccess       : try to deny file access (since 1.20)
 799          *   - noListing      : try to deny file listing (since 1.20)
 800          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 801          * @return StatusValue
 802          */
 803         final public function prepare( array $params ) {
 804                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 805                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 806                 }
 807                 /** @noinspection PhpUnusedLocalVariableInspection */
 808                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 809                 return $this->doPrepare( $params );
 810         }
 811
 812         /**
 813          * @see FileBackend::prepare()
 814          * @param array $params
 815          */
 816         abstract protected function doPrepare( array $params );
 817
 818         /**
 819          * Take measures to block web access to a storage directory and
 820          * the container it belongs to. FS backends might add .htaccess
 821          * files whereas key/value store backends might revoke container
 822          * access to the storage user representing end-users in web requests.
 823          *
 824          * This is not guaranteed to actually make files or listings publically hidden.
 825          * Additional server configuration may be needed to achieve the desired effect.
 826          *
 827          * @param array $params Parameters include:
 828          *   - dir            : storage directory
 829          *   - noAccess       : try to deny file access
 830          *   - noListing      : try to deny file listing
 831          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 832          * @return StatusValue
 833          */
 834         final public function secure( array $params ) {
 835                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 836                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 837                 }
 838                 /** @noinspection PhpUnusedLocalVariableInspection */
 839                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 840                 return $this->doSecure( $params );
 841         }
 842
 843         /**
 844          * @see FileBackend::secure()
 845          * @param array $params
 846          */
 847         abstract protected function doSecure( array $params );
 848
 849         /**
 850          * Remove measures to block web access to a storage directory and
 851          * the container it belongs to. FS backends might remove .htaccess
 852          * files whereas key/value store backends might grant container
 853          * access to the storage user representing end-users in web requests.
 854          * This essentially can undo the result of secure() calls.
 855          *
 856          * This is not guaranteed to actually make files or listings publically viewable.
 857          * Additional server configuration may be needed to achieve the desired effect.
 858          *
 859          * @param array $params Parameters include:
 860          *   - dir            : storage directory
 861          *   - access         : try to allow file access
 862          *   - listing        : try to allow file listing
 863          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 864          * @return StatusValue
 865          * @since 1.20
 866          */
 867         final public function publish( array $params ) {
 868                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 869                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 870                 }
 871                 /** @noinspection PhpUnusedLocalVariableInspection */
 872                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 873                 return $this->doPublish( $params );
 874         }
 875
 876         /**
 877          * @see FileBackend::publish()
 878          * @param array $params
 879          */
 880         abstract protected function doPublish( array $params );
 881
 882         /**
 883          * Delete a storage directory if it is empty.
 884          * Backends using key/value stores may do nothing unless the directory
 885          * is that of an empty container, in which case it will be deleted.
 886          *
 887          * @param array $params Parameters include:
 888          *   - dir            : storage directory
 889          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 890          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 891          * @return StatusValue
 892          */
 893         final public function clean( array $params ) {
 894                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 895                         return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
 896                 }
 897                 /** @noinspection PhpUnusedLocalVariableInspection */
 898                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 899                 return $this->doClean( $params );
 900         }
 901
 902         /**
 903          * @see FileBackend::clean()
 904          * @param array $params
 905          */
 906         abstract protected function doClean( array $params );
 907
 908         /**
 909          * Enter file operation scope.
 910          * This just makes PHP ignore user aborts/disconnects until the return
 911          * value leaves scope. This returns null and does nothing in CLI mode.
 912          *
 913          * @return ScopedCallback|null
 914          */
 915         final protected function getScopedPHPBehaviorForOps() {
 916                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 917                         $old = ignore_user_abort( true ); // avoid half-finished operations
 918                         return new ScopedCallback( function () use ( $old ) {
 919                                 ignore_user_abort( $old );
 920                         } );
 921                 }
 922
 923                 return null;
 924         }
 925
 926         /**
 927          * Check if a file exists at a storage path in the backend.
 928          * This returns false if only a directory exists at the path.
 929          *
 930          * @param array $params Parameters include:
 931          *   - src    : source storage path
 932          *   - latest : use the latest available data
 933          * @return bool|null Returns null on failure
 934          */
 935         abstract public function fileExists( array $params );
 936
 937         /**
 938          * Get the last-modified timestamp of the file at a storage path.
 939          *
 940          * @param array $params Parameters include:
 941          *   - src    : source storage path
 942          *   - latest : use the latest available data
 943          * @return string|bool TS_MW timestamp or false on failure
 944          */
 945         abstract public function getFileTimestamp( array $params );
 946
 947         /**
 948          * Get the contents of a file at a storage path in the backend.
 949          * This should be avoided for potentially large files.
 950          *
 951          * @param array $params Parameters include:
 952          *   - src    : source storage path
 953          *   - latest : use the latest available data
 954          * @return string|bool Returns false on failure
 955          */
 956         final public function getFileContents( array $params ) {
 957                 $contents = $this->getFileContentsMulti(
 958                         [ 'srcs' => [ $params['src'] ] ] + $params );
 959
 960                 return $contents[$params['src']];
 961         }
 962
 963         /**
 964          * Like getFileContents() except it takes an array of storage paths
 965          * and returns a map of storage paths to strings (or null on failure).
 966          * The map keys (paths) are in the same order as the provided list of paths.
 967          *
 968          * @see FileBackend::getFileContents()
 969          *
 970          * @param array $params Parameters include:
 971          *   - srcs        : list of source storage paths
 972          *   - latest      : use the latest available data
 973          *   - parallelize : try to do operations in parallel when possible
 974          * @return array Map of (path name => string or false on failure)
 975          * @since 1.20
 976          */
 977         abstract public function getFileContentsMulti( array $params );
 978
 979         /**
 980          * Get metadata about a file at a storage path in the backend.
 981          * If the file does not exist, then this returns false.
 982          * Otherwise, the result is an associative array that includes:
 983          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 984          *   - metadata : map of file metadata (name => value)
 985          * Metadata keys and headers names will be returned in all lower-case.
 986          * Additional values may be included for internal use only.
 987          *
 988          * Use FileBackend::hasFeatures() to check how well this is supported.
 989          *
 990          * @param array $params
 991          * $params include:
 992          *   - src    : source storage path
 993          *   - latest : use the latest available data
 994          * @return array|bool Returns false on failure
 995          * @since 1.23
 996          */
 997         abstract public function getFileXAttributes( array $params );
 998
 999         /**
1000          * Get the size (bytes) of a file at a storage path in the backend.
1001          *
1002          * @param array $params Parameters include:
1003          *   - src    : source storage path
1004          *   - latest : use the latest available data
1005          * @return int|bool Returns false on failure
1006          */
1007         abstract public function getFileSize( array $params );
1008
1009         /**
1010          * Get quick information about a file at a storage path in the backend.
1011          * If the file does not exist, then this returns false.
1012          * Otherwise, the result is an associative array that includes:
1013          *   - mtime  : the last-modified timestamp (TS_MW)
1014          *   - size   : the file size (bytes)
1015          * Additional values may be included for internal use only.
1016          *
1017          * @param array $params Parameters include:
1018          *   - src    : source storage path
1019          *   - latest : use the latest available data
1020          * @return array|bool|null Returns null on failure
1021          */
1022         abstract public function getFileStat( array $params );
1023
1024         /**
1025          * Get a SHA-1 hash of the file at a storage path in the backend.
1026          *
1027          * @param array $params Parameters include:
1028          *   - src    : source storage path
1029          *   - latest : use the latest available data
1030          * @return string|bool Hash string or false on failure
1031          */
1032         abstract public function getFileSha1Base36( array $params );
1033
1034         /**
1035          * Get the properties of the file at a storage path in the backend.
1036          * This gives the result of FSFile::getProps() on a local copy of the file.
1037          *
1038          * @param array $params Parameters include:
1039          *   - src    : source storage path
1040          *   - latest : use the latest available data
1041          * @return array Returns FSFile::placeholderProps() on failure
1042          */
1043         abstract public function getFileProps( array $params );
1044
1045         /**
1046          * Stream the file at a storage path in the backend.
1047          *
1048          * If the file does not exists, an HTTP 404 error will be given.
1049          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
1050          * will be sent if streaming began, while none will be sent otherwise.
1051          * Implementations should flush the output buffer before sending data.
1052          *
1053          * @param array $params Parameters include:
1054          *   - src      : source storage path
1055          *   - headers  : list of additional HTTP headers to send if the file exists
1056          *   - options  : HTTP request header map with lower case keys (since 1.28). Supports:
1057          *                range             : format is "bytes=(\d*-\d*)"
1058          *                if-modified-since : format is an HTTP date
1059          *   - headless : only include the body (and headers from "headers") (since 1.28)
1060          *   - latest   : use the latest available data
1061          *   - allowOB  : preserve any output buffers (since 1.28)
1062          * @return StatusValue
1063          */
1064         abstract public function streamFile( array $params );
1065
1066         /**
1067          * Returns a file system file, identical to the file at a storage path.
1068          * The file returned is either:
1069          *   - a) A local copy of the file at a storage path in the backend.
1070          *        The temporary copy will have the same extension as the source.
1071          *   - b) An original of the file at a storage path in the backend.
1072          * Temporary files may be purged when the file object falls out of scope.
1073          *
1074          * Write operations should *never* be done on this file as some backends
1075          * may do internal tracking or may be instances of FileBackendMultiWrite.
1076          * In that latter case, there are copies of the file that must stay in sync.
1077          * Additionally, further calls to this function may return the same file.
1078          *
1079          * @param array $params Parameters include:
1080          *   - src    : source storage path
1081          *   - latest : use the latest available data
1082          * @return FSFile|null Returns null on failure
1083          */
1084         final public function getLocalReference( array $params ) {
1085                 $fsFiles = $this->getLocalReferenceMulti(
1086                         [ 'srcs' => [ $params['src'] ] ] + $params );
1087
1088                 return $fsFiles[$params['src']];
1089         }
1090
1091         /**
1092          * Like getLocalReference() except it takes an array of storage paths
1093          * and returns a map of storage paths to FSFile objects (or null on failure).
1094          * The map keys (paths) are in the same order as the provided list of paths.
1095          *
1096          * @see FileBackend::getLocalReference()
1097          *
1098          * @param array $params Parameters include:
1099          *   - srcs        : list of source storage paths
1100          *   - latest      : use the latest available data
1101          *   - parallelize : try to do operations in parallel when possible
1102          * @return array Map of (path name => FSFile or null on failure)
1103          * @since 1.20
1104          */
1105         abstract public function getLocalReferenceMulti( array $params );
1106
1107         /**
1108          * Get a local copy on disk of the file at a storage path in the backend.
1109          * The temporary copy will have the same file extension as the source.
1110          * Temporary files may be purged when the file object falls out of scope.
1111          *
1112          * @param array $params Parameters include:
1113          *   - src    : source storage path
1114          *   - latest : use the latest available data
1115          * @return TempFSFile|null Returns null on failure
1116          */
1117         final public function getLocalCopy( array $params ) {
1118                 $tmpFiles = $this->getLocalCopyMulti(
1119                         [ 'srcs' => [ $params['src'] ] ] + $params );
1120
1121                 return $tmpFiles[$params['src']];
1122         }
1123
1124         /**
1125          * Like getLocalCopy() except it takes an array of storage paths and
1126          * returns a map of storage paths to TempFSFile objects (or null on failure).
1127          * The map keys (paths) are in the same order as the provided list of paths.
1128          *
1129          * @see FileBackend::getLocalCopy()
1130          *
1131          * @param array $params Parameters include:
1132          *   - srcs        : list of source storage paths
1133          *   - latest      : use the latest available data
1134          *   - parallelize : try to do operations in parallel when possible
1135          * @return array Map of (path name => TempFSFile or null on failure)
1136          * @since 1.20
1137          */
1138         abstract public function getLocalCopyMulti( array $params );
1139
1140         /**
1141          * Return an HTTP URL to a given file that requires no authentication to use.
1142          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1143          * This will return null if the backend cannot make an HTTP URL for the file.
1144          *
1145          * This is useful for key/value stores when using scripts that seek around
1146          * large files and those scripts (and the backend) support HTTP Range headers.
1147          * Otherwise, one would need to use getLocalReference(), which involves loading
1148          * the entire file on to local disk.
1149          *
1150          * @param array $params Parameters include:
1151          *   - src : source storage path
1152          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1153          * @return string|null
1154          * @since 1.21
1155          */
1156         abstract public function getFileHttpUrl( array $params );
1157
1158         /**
1159          * Check if a directory exists at a given storage path.
1160          * Backends using key/value stores will check if the path is a
1161          * virtual directory, meaning there are files under the given directory.
1162          *
1163          * Storage backends with eventual consistency might return stale data.
1164          *
1165          * @param array $params Parameters include:
1166          *   - dir : storage directory
1167          * @return bool|null Returns null on failure
1168          * @since 1.20
1169          */
1170         abstract public function directoryExists( array $params );
1171
1172         /**
1173          * Get an iterator to list *all* directories under a storage directory.
1174          * If the directory is of the form "mwstore://backend/container",
1175          * then all directories in the container will be listed.
1176          * If the directory is of form "mwstore://backend/container/dir",
1177          * then all directories directly under that directory will be listed.
1178          * Results will be storage directories relative to the given directory.
1179          *
1180          * Storage backends with eventual consistency might return stale data.
1181          *
1182          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1183          *
1184          * @param array $params Parameters include:
1185          *   - dir     : storage directory
1186          *   - topOnly : only return direct child dirs of the directory
1187          * @return Traversable|array|null Returns null on failure
1188          * @since 1.20
1189          */
1190         abstract public function getDirectoryList( array $params );
1191
1192         /**
1193          * Same as FileBackend::getDirectoryList() except only lists
1194          * directories that are immediately under the given directory.
1195          *
1196          * Storage backends with eventual consistency might return stale data.
1197          *
1198          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1199          *
1200          * @param array $params Parameters include:
1201          *   - dir : storage directory
1202          * @return Traversable|array|null Returns null on failure
1203          * @since 1.20
1204          */
1205         final public function getTopDirectoryList( array $params ) {
1206                 return $this->getDirectoryList( [ 'topOnly' => true ] + $params );
1207         }
1208
1209         /**
1210          * Get an iterator to list *all* stored files under a storage directory.
1211          * If the directory is of the form "mwstore://backend/container",
1212          * then all files in the container will be listed.
1213          * If the directory is of form "mwstore://backend/container/dir",
1214          * then all files under that directory will be listed.
1215          * Results will be storage paths relative to the given directory.
1216          *
1217          * Storage backends with eventual consistency might return stale data.
1218          *
1219          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1220          *
1221          * @param array $params Parameters include:
1222          *   - dir        : storage directory
1223          *   - topOnly    : only return direct child files of the directory (since 1.20)
1224          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1225          * @return Traversable|array|null Returns null on failure
1226          */
1227         abstract public function getFileList( array $params );
1228
1229         /**
1230          * Same as FileBackend::getFileList() except only lists
1231          * files that are immediately under the given directory.
1232          *
1233          * Storage backends with eventual consistency might return stale data.
1234          *
1235          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1236          *
1237          * @param array $params Parameters include:
1238          *   - dir        : storage directory
1239          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1240          * @return Traversable|array|null Returns null on failure
1241          * @since 1.20
1242          */
1243         final public function getTopFileList( array $params ) {
1244                 return $this->getFileList( [ 'topOnly' => true ] + $params );
1245         }
1246
1247         /**
1248          * Preload persistent file stat cache and property cache into in-process cache.
1249          * This should be used when stat calls will be made on a known list of a many files.
1250          *
1251          * @see FileBackend::getFileStat()
1252          *
1253          * @param array $paths Storage paths
1254          */
1255         abstract public function preloadCache( array $paths );
1256
1257         /**
1258          * Invalidate any in-process file stat and property cache.
1259          * If $paths is given, then only the cache for those files will be cleared.
1260          *
1261          * @see FileBackend::getFileStat()
1262          *
1263          * @param array $paths Storage paths (optional)
1264          */
1265         abstract public function clearCache( array $paths = null );
1266
1267         /**
1268          * Preload file stat information (concurrently if possible) into in-process cache.
1269          *
1270          * This should be used when stat calls will be made on a known list of a many files.
1271          * This does not make use of the persistent file stat cache.
1272          *
1273          * @see FileBackend::getFileStat()
1274          *
1275          * @param array $params Parameters include:
1276          *   - srcs        : list of source storage paths
1277          *   - latest      : use the latest available data
1278          * @return bool All requests proceeded without I/O errors (since 1.24)
1279          * @since 1.23
1280          */
1281         abstract public function preloadFileStat( array $params );
1282
1283         /**
1284          * Lock the files at the given storage paths in the backend.
1285          * This will either lock all the files or none (on failure).
1286          *
1287          * Callers should consider using getScopedFileLocks() instead.
1288          *
1289          * @param array $paths Storage paths
1290          * @param int $type LockManager::LOCK_* constant
1291          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1292          * @return StatusValue
1293          */
1294         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1295                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1296
1297                 return $this->wrapStatus( $this->lockManager->lock( $paths, $type, $timeout ) );
1298         }
1299
1300         /**
1301          * Unlock the files at the given storage paths in the backend.
1302          *
1303          * @param array $paths Storage paths
1304          * @param int $type LockManager::LOCK_* constant
1305          * @return StatusValue
1306          */
1307         final public function unlockFiles( array $paths, $type ) {
1308                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1309
1310                 return $this->wrapStatus( $this->lockManager->unlock( $paths, $type ) );
1311         }
1312
1313         /**
1314          * Lock the files at the given storage paths in the backend.
1315          * This will either lock all the files or none (on failure).
1316          * On failure, the StatusValue object will be updated with errors.
1317          *
1318          * Once the return value goes out scope, the locks will be released and
1319          * the StatusValue updated. Unlock fatals will not change the StatusValue "OK" value.
1320          *
1321          * @see ScopedLock::factory()
1322          *
1323          * @param array $paths List of storage paths or map of lock types to path lists
1324          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1325          * @param StatusValue $status StatusValue to update on lock/unlock
1326          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1327          * @return ScopedLock|null Returns null on failure
1328          */
1329         final public function getScopedFileLocks(
1330                 array $paths, $type, StatusValue $status, $timeout = 0
1331         ) {
1332                 if ( $type === 'mixed' ) {
1333                         foreach ( $paths as &$typePaths ) {
1334                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1335                         }
1336                 } else {
1337                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1338                 }
1339
1340                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1341         }
1342
1343         /**
1344          * Get an array of scoped locks needed for a batch of file operations.
1345          *
1346          * Normally, FileBackend::doOperations() handles locking, unless
1347          * the 'nonLocking' param is passed in. This function is useful if you
1348          * want the files to be locked for a broader scope than just when the
1349          * files are changing. For example, if you need to update DB metadata,
1350          * you may want to keep the files locked until finished.
1351          *
1352          * @see FileBackend::doOperations()
1353          *
1354          * @param array $ops List of file operations to FileBackend::doOperations()
1355          * @param StatusValue $status StatusValue to update on lock/unlock
1356          * @return ScopedLock|null
1357          * @since 1.20
1358          */
1359         abstract public function getScopedLocksForOps( array $ops, StatusValue $status );
1360
1361         /**
1362          * Get the root storage path of this backend.
1363          * All container paths are "subdirectories" of this path.
1364          *
1365          * @return string Storage path
1366          * @since 1.20
1367          */
1368         final public function getRootStoragePath() {
1369                 return "mwstore://{$this->name}";
1370         }
1371
1372         /**
1373          * Get the storage path for the given container for this backend
1374          *
1375          * @param string $container Container name
1376          * @return string Storage path
1377          * @since 1.21
1378          */
1379         final public function getContainerStoragePath( $container ) {
1380                 return $this->getRootStoragePath() . "/{$container}";
1381         }
1382
1383         /**
1384          * Get the file journal object for this backend
1385          *
1386          * @return FileJournal
1387          */
1388         final public function getJournal() {
1389                 return $this->fileJournal;
1390         }
1391
1392         /**
1393          * Convert FSFile 'src' paths to string paths (with an 'srcRef' field set to the FSFile)
1394          *
1395          * The 'srcRef' field keeps any TempFSFile objects in scope for the backend to have it
1396          * around as long it needs (which may vary greatly depending on configuration)
1397          *
1398          * @param array $ops File operation batch for FileBaclend::doOperations()
1399          * @return array File operation batch
1400          */
1401         protected function resolveFSFileObjects( array $ops ) {
1402                 foreach ( $ops as &$op ) {
1403                         $src = isset( $op['src'] ) ? $op['src'] : null;
1404                         if ( $src instanceof FSFile ) {
1405                                 $op['srcRef'] = $src;
1406                                 $op['src'] = $src->getPath();
1407                         }
1408                 }
1409                 unset( $op );
1410
1411                 return $ops;
1412         }
1413
1414         /**
1415          * Check if a given path is a "mwstore://" path.
1416          * This does not do any further validation or any existence checks.
1417          *
1418          * @param string $path
1419          * @return bool
1420          */
1421         final public static function isStoragePath( $path ) {
1422                 return ( strpos( $path, 'mwstore://' ) === 0 );
1423         }
1424
1425         /**
1426          * Split a storage path into a backend name, a container name,
1427          * and a relative file path. The relative path may be the empty string.
1428          * This does not do any path normalization or traversal checks.
1429          *
1430          * @param string $storagePath
1431          * @return array (backend, container, rel object) or (null, null, null)
1432          */
1433         final public static function splitStoragePath( $storagePath ) {
1434                 if ( self::isStoragePath( $storagePath ) ) {
1435                         // Remove the "mwstore://" prefix and split the path
1436                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1437                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1438                                 if ( count( $parts ) == 3 ) {
1439                                         return $parts; // e.g. "backend/container/path"
1440                                 } else {
1441                                         return [ $parts[0], $parts[1], '' ]; // e.g. "backend/container"
1442                                 }
1443                         }
1444                 }
1445
1446                 return [ null, null, null ];
1447         }
1448
1449         /**
1450          * Normalize a storage path by cleaning up directory separators.
1451          * Returns null if the path is not of the format of a valid storage path.
1452          *
1453          * @param string $storagePath
1454          * @return string|null
1455          */
1456         final public static function normalizeStoragePath( $storagePath ) {
1457                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1458                 if ( $relPath !== null ) { // must be for this backend
1459                         $relPath = self::normalizeContainerPath( $relPath );
1460                         if ( $relPath !== null ) {
1461                                 return ( $relPath != '' )
1462                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1463                                         : "mwstore://{$backend}/{$container}";
1464                         }
1465                 }
1466
1467                 return null;
1468         }
1469
1470         /**
1471          * Get the parent storage directory of a storage path.
1472          * This returns a path like "mwstore://backend/container",
1473          * "mwstore://backend/container/...", or null if there is no parent.
1474          *
1475          * @param string $storagePath
1476          * @return string|null
1477          */
1478         final public static function parentStoragePath( $storagePath ) {
1479                 $storagePath = dirname( $storagePath );
1480                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1481
1482                 return ( $rel === null ) ? null : $storagePath;
1483         }
1484
1485         /**
1486          * Get the final extension from a storage or FS path
1487          *
1488          * @param string $path
1489          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1490          * @return string
1491          */
1492         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1493                 $i = strrpos( $path, '.' );
1494                 $ext = $i ? substr( $path, $i + 1 ) : '';
1495
1496                 if ( $case === 'lowercase' ) {
1497                         $ext = strtolower( $ext );
1498                 } elseif ( $case === 'uppercase' ) {
1499                         $ext = strtoupper( $ext );
1500                 }
1501
1502                 return $ext;
1503         }
1504
1505         /**
1506          * Check if a relative path has no directory traversals
1507          *
1508          * @param string $path
1509          * @return bool
1510          * @since 1.20
1511          */
1512         final public static function isPathTraversalFree( $path ) {
1513                 return ( self::normalizeContainerPath( $path ) !== null );
1514         }
1515
1516         /**
1517          * Build a Content-Disposition header value per RFC 6266.
1518          *
1519          * @param string $type One of (attachment, inline)
1520          * @param string $filename Suggested file name (should not contain slashes)
1521          * @throws FileBackendError
1522          * @return string
1523          * @since 1.20
1524          */
1525         final public static function makeContentDisposition( $type, $filename = '' ) {
1526                 $parts = [];
1527
1528                 $type = strtolower( $type );
1529                 if ( !in_array( $type, [ 'inline', 'attachment' ] ) ) {
1530                         throw new InvalidArgumentException( "Invalid Content-Disposition type '$type'." );
1531                 }
1532                 $parts[] = $type;
1533
1534                 if ( strlen( $filename ) ) {
1535                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1536                 }
1537
1538                 return implode( ';', $parts );
1539         }
1540
1541         /**
1542          * Validate and normalize a relative storage path.
1543          * Null is returned if the path involves directory traversal.
1544          * Traversal is insecure for FS backends and broken for others.
1545          *
1546          * This uses the same traversal protection as Title::secureAndSplit().
1547          *
1548          * @param string $path Storage path relative to a container
1549          * @return string|null
1550          */
1551         final protected static function normalizeContainerPath( $path ) {
1552                 // Normalize directory separators
1553                 $path = strtr( $path, '\\', '/' );
1554                 // Collapse any consecutive directory separators
1555                 $path = preg_replace( '![/]{2,}!', '/', $path );
1556                 // Remove any leading directory separator
1557                 $path = ltrim( $path, '/' );
1558                 // Use the same traversal protection as Title::secureAndSplit()
1559                 if ( strpos( $path, '.' ) !== false ) {
1560                         if (
1561                                 $path === '.' ||
1562                                 $path === '..' ||
1563                                 strpos( $path, './' ) === 0 ||
1564                                 strpos( $path, '../' ) === 0 ||
1565                                 strpos( $path, '/./' ) !== false ||
1566                                 strpos( $path, '/../' ) !== false
1567                         ) {
1568                                 return null;
1569                         }
1570                 }
1571
1572                 return $path;
1573         }
1574
1575         /**
1576          * Yields the result of the status wrapper callback on either:
1577          *   - StatusValue::newGood() if this method is called without parameters
1578          *   - StatusValue::newFatal() with all parameters to this method if passed in
1579          *
1580          * @param ... string
1581          * @return StatusValue
1582          */
1583         final protected function newStatus() {
1584                 $args = func_get_args();
1585                 if ( count( $args ) ) {
1586                         $sv = call_user_func_array( [ 'StatusValue', 'newFatal' ], $args );
1587                 } else {
1588                         $sv = StatusValue::newGood();
1589                 }
1590
1591                 return $this->wrapStatus( $sv );
1592         }
1593
1594         /**
1595          * @param StatusValue $sv
1596          * @return StatusValue Modified status or StatusValue subclass
1597          */
1598         final protected function wrapStatus( StatusValue $sv ) {
1599                 return $this->statusWrapper ? call_user_func( $this->statusWrapper, $sv ) : $sv;
1600         }
1601
1602         /**
1603          * @param string $section
1604          * @return ScopedCallback|null
1605          */
1606         protected function scopedProfileSection( $section ) {
1607                 if ( $this->profiler ) {
1608                         call_user_func( [ $this->profiler, 'profileIn' ], $section );
1609                         return new ScopedCallback( [ $this->profiler, 'profileOut' ] );
1610                 }
1611
1612                 return null;
1613         }
1614 }