includes/filebackend/FileBackend.php

   1 <?php
   2 /**
   3  * @defgroup FileBackend File backend
   4  *
   5  * File backend is used to interact with file storage systems,
   6  * such as the local file system, NFS, or cloud storage systems.
   7  */
   8
   9 /**
  10  * Base class for all file backends.
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along
  23  * with this program; if not, write to the Free Software Foundation, Inc.,
  24  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  25  * http://www.gnu.org/copyleft/gpl.html
  26  *
  27  * @file
  28  * @ingroup FileBackend
  29  * @author Aaron Schulz
  30  */
  31
  32 /**
  33  * @brief Base class for all file backend classes (including multi-write backends).
  34  *
  35  * This class defines the methods as abstract that subclasses must implement.
  36  * Outside callers can assume that all backends will have these functions.
  37  *
  38  * All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
  39  * The "backend" portion is unique name for MediaWiki to refer to a backend, while
  40  * the "container" portion is a top-level directory of the backend. The "path" portion
  41  * is a relative path that uses UNIX file system (FS) notation, though any particular
  42  * backend may not actually be using a local filesystem. Therefore, the relative paths
  43  * are only virtual.
  44  *
  45  * Backend contents are stored under wiki-specific container names by default.
  46  * Global (qualified) backends are achieved by configuring the "wiki ID" to a constant.
  47  * For legacy reasons, the FSFileBackend class allows manually setting the paths of
  48  * containers to ones that do not respect the "wiki ID".
  49  *
  50  * In key/value (object) stores, containers are the only hierarchy (the rest is emulated).
  51  * FS-based backends are somewhat more restrictive due to the existence of real
  52  * directory files; a regular file cannot have the same name as a directory. Other
  53  * backends with virtual directories may not have this limitation. Callers should
  54  * store files in such a way that no files and directories are under the same path.
  55  *
  56  * In general, this class allows for callers to access storage through the same
  57  * interface, without regard to the underlying storage system. However, calling code
  58  * must follow certain patterns and be aware of certain things to ensure compatibility:
  59  *   - a) Always call prepare() on the parent directory before trying to put a file there;
  60  *        key/value stores only need the container to exist first, but filesystems need
  61  *        all the parent directories to exist first (prepare() is aware of all this)
  62  *   - b) Always call clean() on a directory when it might become empty to avoid empty
  63  *        directory buildup on filesystems; key/value stores never have empty directories,
  64  *        so doing this helps preserve consistency in both cases
  65  *   - c) Likewise, do not rely on the existence of empty directories for anything;
  66  *        calling directoryExists() on a path that prepare() was previously called on
  67  *        will return false for key/value stores if there are no files under that path
  68  *   - d) Never alter the resulting FSFile returned from getLocalReference(), as it could
  69  *        either be a copy of the source file in /tmp or the original source file itself
  70  *   - e) Use a file layout that results in never attempting to store files over directories
  71  *        or directories over files; key/value stores allow this but filesystems do not
  72  *   - f) Use ASCII file names (e.g. base32, IDs, hashes) to avoid Unicode issues in Windows
  73  *   - g) Do not assume that move operations are atomic (difficult with key/value stores)
  74  *   - h) Do not assume that file stat or read operations always have immediate consistency;
  75  *        various methods have a "latest" flag that should always be used if up-to-date
  76  *        information is required (this trades performance for correctness as needed)
  77  *   - i) Do not assume that directory listings have immediate consistency
  78  *
  79  * Methods of subclasses should avoid throwing exceptions at all costs.
  80  * As a corollary, external dependencies should be kept to a minimum.
  81  *
  82  * @ingroup FileBackend
  83  * @since 1.19
  84  */
  85 abstract class FileBackend {
  86         /** @var string Unique backend name */
  87         protected $name;
  88
  89         /** @var string Unique wiki name */
  90         protected $wikiId;
  91
  92         /** @var string Read-only explanation message */
  93         protected $readOnly;
  94
  95         /** @var string When to do operations in parallel */
  96         protected $parallelize;
  97
  98         /** @var int How many operations can be done in parallel */
  99         protected $concurrency;
 100
 101         /** @var LockManager */
 102         protected $lockManager;
 103
 104         /** @var FileJournal */
 105         protected $fileJournal;
 106
 107         /** Bitfield flags for supported features */
 108         const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
 109         const ATTR_METADATA = 2; // files can be stored with metadata key/values
 110         const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
 111
 112         /**
 113          * Create a new backend instance from configuration.
 114          * This should only be called from within FileBackendGroup.
 115          *
 116          * @param array $config Parameters include:
 117          *   - name        : The unique name of this backend.
 118          *                   This should consist of alphanumberic, '-', and '_' characters.
 119          *                   This name should not be changed after use (e.g. with journaling).
 120          *                   Note that the name is *not* used in actual container names.
 121          *   - wikiId      : Prefix to container names that is unique to this backend.
 122          *                   It should only consist of alphanumberic, '-', and '_' characters.
 123          *                   This ID is what avoids collisions if multiple logical backends
 124          *                   use the same storage system, so this should be set carefully.
 125          *   - lockManager : LockManager object to use for any file locking.
 126          *                   If not provided, then no file locking will be enforced.
 127          *   - fileJournal : FileJournal object to use for logging changes to files.
 128          *                   If not provided, then change journaling will be disabled.
 129          *   - readOnly    : Write operations are disallowed if this is a non-empty string.
 130          *                   It should be an explanation for the backend being read-only.
 131          *   - parallelize : When to do file operations in parallel (when possible).
 132          *                   Allowed values are "implicit", "explicit" and "off".
 133          *   - concurrency : How many file operations can be done in parallel.
 134          * @throws FileBackendException
 135          */
 136         public function __construct( array $config ) {
 137                 $this->name = $config['name'];
 138                 $this->wikiId = $config['wikiId']; // e.g. "my_wiki-en_"
 139                 if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
 140                         throw new FileBackendException( "Backend name '{$this->name}' is invalid." );
 141                 } elseif ( !is_string( $this->wikiId ) ) {
 142                         throw new FileBackendException( "Backend wiki ID not provided for '{$this->name}'." );
 143                 }
 144                 $this->lockManager = isset( $config['lockManager'] )
 145                         ? $config['lockManager']
 146                         : new NullLockManager( array() );
 147                 $this->fileJournal = isset( $config['fileJournal'] )
 148                         ? $config['fileJournal']
 149                         : FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
 150                 $this->readOnly = isset( $config['readOnly'] )
 151                         ? (string)$config['readOnly']
 152                         : '';
 153                 $this->parallelize = isset( $config['parallelize'] )
 154                         ? (string)$config['parallelize']
 155                         : 'off';
 156                 $this->concurrency = isset( $config['concurrency'] )
 157                         ? (int)$config['concurrency']
 158                         : 50;
 159         }
 160
 161         /**
 162          * Get the unique backend name.
 163          * We may have multiple different backends of the same type.
 164          * For example, we can have two Swift backends using different proxies.
 165          *
 166          * @return string
 167          */
 168         final public function getName() {
 169                 return $this->name;
 170         }
 171
 172         /**
 173          * Get the wiki identifier used for this backend (possibly empty).
 174          * Note that this might *not* be in the same format as wfWikiID().
 175          *
 176          * @return string
 177          * @since 1.20
 178          */
 179         final public function getWikiId() {
 180                 return $this->wikiId;
 181         }
 182
 183         /**
 184          * Check if this backend is read-only
 185          *
 186          * @return bool
 187          */
 188         final public function isReadOnly() {
 189                 return ( $this->readOnly != '' );
 190         }
 191
 192         /**
 193          * Get an explanatory message if this backend is read-only
 194          *
 195          * @return string|bool Returns false if the backend is not read-only
 196          */
 197         final public function getReadOnlyReason() {
 198                 return ( $this->readOnly != '' ) ? $this->readOnly : false;
 199         }
 200
 201         /**
 202          * Get the a bitfield of extra features supported by the backend medium
 203          *
 204          * @return int Bitfield of FileBackend::ATTR_* flags
 205          * @since 1.23
 206          */
 207         public function getFeatures() {
 208                 return self::ATTR_UNICODE_PATHS;
 209         }
 210
 211         /**
 212          * Check if the backend medium supports a field of extra features
 213          *
 214          * @param int $bitfield Bitfield of FileBackend::ATTR_* flags
 215          * @return bool
 216          * @since 1.23
 217          */
 218         final public function hasFeatures( $bitfield ) {
 219                 return ( $this->getFeatures() & $bitfield ) === $bitfield;
 220         }
 221
 222         /**
 223          * This is the main entry point into the backend for write operations.
 224          * Callers supply an ordered list of operations to perform as a transaction.
 225          * Files will be locked, the stat cache cleared, and then the operations attempted.
 226          * If any serious errors occur, all attempted operations will be rolled back.
 227          *
 228          * $ops is an array of arrays. The outer array holds a list of operations.
 229          * Each inner array is a set of key value pairs that specify an operation.
 230          *
 231          * Supported operations and their parameters. The supported actions are:
 232          *  - create
 233          *  - store
 234          *  - copy
 235          *  - move
 236          *  - delete
 237          *  - describe (since 1.21)
 238          *  - null
 239          *
 240          * a) Create a new file in storage with the contents of a string
 241          * @code
 242          *     array(
 243          *         'op'                  => 'create',
 244          *         'dst'                 => <storage path>,
 245          *         'content'             => <string of new file contents>,
 246          *         'overwrite'           => <boolean>,
 247          *         'overwriteSame'       => <boolean>,
 248          *         'headers'             => <HTTP header name/value map> # since 1.21
 249          *     );
 250          * @endcode
 251          *
 252          * b) Copy a file system file into storage
 253          * @code
 254          *     array(
 255          *         'op'                  => 'store',
 256          *         'src'                 => <file system path>,
 257          *         'dst'                 => <storage path>,
 258          *         'overwrite'           => <boolean>,
 259          *         'overwriteSame'       => <boolean>,
 260          *         'headers'             => <HTTP header name/value map> # since 1.21
 261          *     )
 262          * @endcode
 263          *
 264          * c) Copy a file within storage
 265          * @code
 266          *     array(
 267          *         'op'                  => 'copy',
 268          *         'src'                 => <storage path>,
 269          *         'dst'                 => <storage path>,
 270          *         'overwrite'           => <boolean>,
 271          *         'overwriteSame'       => <boolean>,
 272          *         'ignoreMissingSource' => <boolean>, # since 1.21
 273          *         'headers'             => <HTTP header name/value map> # since 1.21
 274          *     )
 275          * @endcode
 276          *
 277          * d) Move a file within storage
 278          * @code
 279          *     array(
 280          *         'op'                  => 'move',
 281          *         'src'                 => <storage path>,
 282          *         'dst'                 => <storage path>,
 283          *         'overwrite'           => <boolean>,
 284          *         'overwriteSame'       => <boolean>,
 285          *         'ignoreMissingSource' => <boolean>, # since 1.21
 286          *         'headers'             => <HTTP header name/value map> # since 1.21
 287          *     )
 288          * @endcode
 289          *
 290          * e) Delete a file within storage
 291          * @code
 292          *     array(
 293          *         'op'                  => 'delete',
 294          *         'src'                 => <storage path>,
 295          *         'ignoreMissingSource' => <boolean>
 296          *     )
 297          * @endcode
 298          *
 299          * f) Update metadata for a file within storage
 300          * @code
 301          *     array(
 302          *         'op'                  => 'describe',
 303          *         'src'                 => <storage path>,
 304          *         'headers'             => <HTTP header name/value map>
 305          *     )
 306          * @endcode
 307          *
 308          * g) Do nothing (no-op)
 309          * @code
 310          *     array(
 311          *         'op'                  => 'null',
 312          *     )
 313          * @endcode
 314          *
 315          * Boolean flags for operations (operation-specific):
 316          *   - ignoreMissingSource : The operation will simply succeed and do
 317          *                           nothing if the source file does not exist.
 318          *   - overwrite           : Any destination file will be overwritten.
 319          *   - overwriteSame       : If a file already exists at the destination with the
 320          *                           same contents, then do nothing to the destination file
 321          *                           instead of giving an error. This does not compare headers.
 322          *                           This option is ignored if 'overwrite' is already provided.
 323          *   - headers             : If supplied, the result of merging these headers with any
 324          *                           existing source file headers (replacing conflicting ones)
 325          *                           will be set as the destination file headers. Headers are
 326          *                           deleted if their value is set to the empty string. When a
 327          *                           file has headers they are included in responses to GET and
 328          *                           HEAD requests to the backing store for that file.
 329          *                           Header values should be no larger than 255 bytes, except for
 330          *                           Content-Disposition. The system might ignore or truncate any
 331          *                           headers that are too long to store (exact limits will vary).
 332          *                           Backends that don't support metadata ignore this. (since 1.21)
 333          *
 334          * $opts is an associative of boolean flags, including:
 335          *   - force               : Operation precondition errors no longer trigger an abort.
 336          *                           Any remaining operations are still attempted. Unexpected
 337          *                           failures may still cause remaining operations to be aborted.
 338          *   - nonLocking          : No locks are acquired for the operations.
 339          *                           This can increase performance for non-critical writes.
 340          *                           This has no effect unless the 'force' flag is set.
 341          *   - nonJournaled        : Don't log this operation batch in the file journal.
 342          *                           This limits the ability of recovery scripts.
 343          *   - parallelize         : Try to do operations in parallel when possible.
 344          *   - bypassReadOnly      : Allow writes in read-only mode. (since 1.20)
 345          *   - preserveCache       : Don't clear the process cache before checking files.
 346          *                           This should only be used if all entries in the process
 347          *                           cache were added after the files were already locked. (since 1.20)
 348          *
 349          * @remarks Remarks on locking:
 350          * File system paths given to operations should refer to files that are
 351          * already locked or otherwise safe from modification from other processes.
 352          * Normally these files will be new temp files, which should be adequate.
 353          *
 354          * @par Return value:
 355          *
 356          * This returns a Status, which contains all warnings and fatals that occurred
 357          * during the operation. The 'failCount', 'successCount', and 'success' members
 358          * will reflect each operation attempted.
 359          *
 360          * The status will be "OK" unless:
 361          *   - a) unexpected operation errors occurred (network partitions, disk full...)
 362          *   - b) significant operation errors occurred and 'force' was not set
 363          *
 364          * @param array $ops List of operations to execute in order
 365          * @param array $opts Batch operation options
 366          * @return Status
 367          */
 368         final public function doOperations( array $ops, array $opts = array() ) {
 369                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 370                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 371                 }
 372                 if ( !count( $ops ) ) {
 373                         return Status::newGood(); // nothing to do
 374                 }
 375                 if ( empty( $opts['force'] ) ) { // sanity
 376                         unset( $opts['nonLocking'] );
 377                 }
 378                 foreach ( $ops as &$op ) {
 379                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 380                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 381                         }
 382                 }
 383                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 384                 return $this->doOperationsInternal( $ops, $opts );
 385         }
 386
 387         /**
 388          * @see FileBackend::doOperations()
 389          */
 390         abstract protected function doOperationsInternal( array $ops, array $opts );
 391
 392         /**
 393          * Same as doOperations() except it takes a single operation.
 394          * If you are doing a batch of operations that should either
 395          * all succeed or all fail, then use that function instead.
 396          *
 397          * @see FileBackend::doOperations()
 398          *
 399          * @param array $op Operation
 400          * @param array $opts Operation options
 401          * @return Status
 402          */
 403         final public function doOperation( array $op, array $opts = array() ) {
 404                 return $this->doOperations( array( $op ), $opts );
 405         }
 406
 407         /**
 408          * Performs a single create operation.
 409          * This sets $params['op'] to 'create' and passes it to doOperation().
 410          *
 411          * @see FileBackend::doOperation()
 412          *
 413          * @param array $params Operation parameters
 414          * @param array $opts Operation options
 415          * @return Status
 416          */
 417         final public function create( array $params, array $opts = array() ) {
 418                 return $this->doOperation( array( 'op' => 'create' ) + $params, $opts );
 419         }
 420
 421         /**
 422          * Performs a single store operation.
 423          * This sets $params['op'] to 'store' and passes it to doOperation().
 424          *
 425          * @see FileBackend::doOperation()
 426          *
 427          * @param array $params Operation parameters
 428          * @param array $opts Operation options
 429          * @return Status
 430          */
 431         final public function store( array $params, array $opts = array() ) {
 432                 return $this->doOperation( array( 'op' => 'store' ) + $params, $opts );
 433         }
 434
 435         /**
 436          * Performs a single copy operation.
 437          * This sets $params['op'] to 'copy' and passes it to doOperation().
 438          *
 439          * @see FileBackend::doOperation()
 440          *
 441          * @param array $params Operation parameters
 442          * @param array $opts Operation options
 443          * @return Status
 444          */
 445         final public function copy( array $params, array $opts = array() ) {
 446                 return $this->doOperation( array( 'op' => 'copy' ) + $params, $opts );
 447         }
 448
 449         /**
 450          * Performs a single move operation.
 451          * This sets $params['op'] to 'move' and passes it to doOperation().
 452          *
 453          * @see FileBackend::doOperation()
 454          *
 455          * @param array $params Operation parameters
 456          * @param array $opts Operation options
 457          * @return Status
 458          */
 459         final public function move( array $params, array $opts = array() ) {
 460                 return $this->doOperation( array( 'op' => 'move' ) + $params, $opts );
 461         }
 462
 463         /**
 464          * Performs a single delete operation.
 465          * This sets $params['op'] to 'delete' and passes it to doOperation().
 466          *
 467          * @see FileBackend::doOperation()
 468          *
 469          * @param array $params Operation parameters
 470          * @param array $opts Operation options
 471          * @return Status
 472          */
 473         final public function delete( array $params, array $opts = array() ) {
 474                 return $this->doOperation( array( 'op' => 'delete' ) + $params, $opts );
 475         }
 476
 477         /**
 478          * Performs a single describe operation.
 479          * This sets $params['op'] to 'describe' and passes it to doOperation().
 480          *
 481          * @see FileBackend::doOperation()
 482          *
 483          * @param array $params Operation parameters
 484          * @param array $opts Operation options
 485          * @return Status
 486          * @since 1.21
 487          */
 488         final public function describe( array $params, array $opts = array() ) {
 489                 return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
 490         }
 491
 492         /**
 493          * Perform a set of independent file operations on some files.
 494          *
 495          * This does no locking, nor journaling, and possibly no stat calls.
 496          * Any destination files that already exist will be overwritten.
 497          * This should *only* be used on non-original files, like cache files.
 498          *
 499          * Supported operations and their parameters:
 500          *  - create
 501          *  - store
 502          *  - copy
 503          *  - move
 504          *  - delete
 505          *  - describe (since 1.21)
 506          *  - null
 507          *
 508          * a) Create a new file in storage with the contents of a string
 509          * @code
 510          *     array(
 511          *         'op'                  => 'create',
 512          *         'dst'                 => <storage path>,
 513          *         'content'             => <string of new file contents>,
 514          *         'headers'             => <HTTP header name/value map> # since 1.21
 515          *     )
 516          * @endcode
 517          *
 518          * b) Copy a file system file into storage
 519          * @code
 520          *     array(
 521          *         'op'                  => 'store',
 522          *         'src'                 => <file system path>,
 523          *         'dst'                 => <storage path>,
 524          *         'headers'             => <HTTP header name/value map> # since 1.21
 525          *     )
 526          * @endcode
 527          *
 528          * c) Copy a file within storage
 529          * @code
 530          *     array(
 531          *         'op'                  => 'copy',
 532          *         'src'                 => <storage path>,
 533          *         'dst'                 => <storage path>,
 534          *         'ignoreMissingSource' => <boolean>, # since 1.21
 535          *         'headers'             => <HTTP header name/value map> # since 1.21
 536          *     )
 537          * @endcode
 538          *
 539          * d) Move a file within storage
 540          * @code
 541          *     array(
 542          *         'op'                  => 'move',
 543          *         'src'                 => <storage path>,
 544          *         'dst'                 => <storage path>,
 545          *         'ignoreMissingSource' => <boolean>, # since 1.21
 546          *         'headers'             => <HTTP header name/value map> # since 1.21
 547          *     )
 548          * @endcode
 549          *
 550          * e) Delete a file within storage
 551          * @code
 552          *     array(
 553          *         'op'                  => 'delete',
 554          *         'src'                 => <storage path>,
 555          *         'ignoreMissingSource' => <boolean>
 556          *     )
 557          * @endcode
 558          *
 559          * f) Update metadata for a file within storage
 560          * @code
 561          *     array(
 562          *         'op'                  => 'describe',
 563          *         'src'                 => <storage path>,
 564          *         'headers'             => <HTTP header name/value map>
 565          *     )
 566          * @endcode
 567          *
 568          * g) Do nothing (no-op)
 569          * @code
 570          *     array(
 571          *         'op'                  => 'null',
 572          *     )
 573          * @endcode
 574          *
 575          * @par Boolean flags for operations (operation-specific):
 576          *   - ignoreMissingSource : The operation will simply succeed and do
 577          *                           nothing if the source file does not exist.
 578          *   - headers             : If supplied with a header name/value map, the backend will
 579          *                           reply with these headers when GETs/HEADs of the destination
 580          *                           file are made. Header values should be smaller than 256 bytes.
 581          *                           Content-Disposition headers can be longer, though the system
 582          *                           might ignore or truncate ones that are too long to store.
 583          *                           Existing headers will remain, but these will replace any
 584          *                           conflicting previous headers, and headers will be removed
 585          *                           if they are set to an empty string.
 586          *                           Backends that don't support metadata ignore this. (since 1.21)
 587          *
 588          * $opts is an associative of boolean flags, including:
 589          *   - bypassReadOnly      : Allow writes in read-only mode (since 1.20)
 590          *
 591          * @par Return value:
 592          * This returns a Status, which contains all warnings and fatals that occurred
 593          * during the operation. The 'failCount', 'successCount', and 'success' members
 594          * will reflect each operation attempted for the given files. The status will be
 595          * considered "OK" as long as no fatal errors occurred.
 596          *
 597          * @param array $ops Set of operations to execute
 598          * @param array $opts Batch operation options
 599          * @return Status
 600          * @since 1.20
 601          */
 602         final public function doQuickOperations( array $ops, array $opts = array() ) {
 603                 if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
 604                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 605                 }
 606                 if ( !count( $ops ) ) {
 607                         return Status::newGood(); // nothing to do
 608                 }
 609                 foreach ( $ops as &$op ) {
 610                         $op['overwrite'] = true; // avoids RTTs in key/value stores
 611                         if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
 612                                 $op['headers']['Content-Disposition'] = $op['disposition'];
 613                         }
 614                 }
 615                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 616                 return $this->doQuickOperationsInternal( $ops );
 617         }
 618
 619         /**
 620          * @see FileBackend::doQuickOperations()
 621          * @since 1.20
 622          */
 623         abstract protected function doQuickOperationsInternal( array $ops );
 624
 625         /**
 626          * Same as doQuickOperations() except it takes a single operation.
 627          * If you are doing a batch of operations, then use that function instead.
 628          *
 629          * @see FileBackend::doQuickOperations()
 630          *
 631          * @param array $op Operation
 632          * @return Status
 633          * @since 1.20
 634          */
 635         final public function doQuickOperation( array $op ) {
 636                 return $this->doQuickOperations( array( $op ) );
 637         }
 638
 639         /**
 640          * Performs a single quick create operation.
 641          * This sets $params['op'] to 'create' and passes it to doQuickOperation().
 642          *
 643          * @see FileBackend::doQuickOperation()
 644          *
 645          * @param array $params Operation parameters
 646          * @return Status
 647          * @since 1.20
 648          */
 649         final public function quickCreate( array $params ) {
 650                 return $this->doQuickOperation( array( 'op' => 'create' ) + $params );
 651         }
 652
 653         /**
 654          * Performs a single quick store operation.
 655          * This sets $params['op'] to 'store' and passes it to doQuickOperation().
 656          *
 657          * @see FileBackend::doQuickOperation()
 658          *
 659          * @param array $params Operation parameters
 660          * @return Status
 661          * @since 1.20
 662          */
 663         final public function quickStore( array $params ) {
 664                 return $this->doQuickOperation( array( 'op' => 'store' ) + $params );
 665         }
 666
 667         /**
 668          * Performs a single quick copy operation.
 669          * This sets $params['op'] to 'copy' and passes it to doQuickOperation().
 670          *
 671          * @see FileBackend::doQuickOperation()
 672          *
 673          * @param array $params Operation parameters
 674          * @return Status
 675          * @since 1.20
 676          */
 677         final public function quickCopy( array $params ) {
 678                 return $this->doQuickOperation( array( 'op' => 'copy' ) + $params );
 679         }
 680
 681         /**
 682          * Performs a single quick move operation.
 683          * This sets $params['op'] to 'move' and passes it to doQuickOperation().
 684          *
 685          * @see FileBackend::doQuickOperation()
 686          *
 687          * @param array $params Operation parameters
 688          * @return Status
 689          * @since 1.20
 690          */
 691         final public function quickMove( array $params ) {
 692                 return $this->doQuickOperation( array( 'op' => 'move' ) + $params );
 693         }
 694
 695         /**
 696          * Performs a single quick delete operation.
 697          * This sets $params['op'] to 'delete' and passes it to doQuickOperation().
 698          *
 699          * @see FileBackend::doQuickOperation()
 700          *
 701          * @param array $params Operation parameters
 702          * @return Status
 703          * @since 1.20
 704          */
 705         final public function quickDelete( array $params ) {
 706                 return $this->doQuickOperation( array( 'op' => 'delete' ) + $params );
 707         }
 708
 709         /**
 710          * Performs a single quick describe operation.
 711          * This sets $params['op'] to 'describe' and passes it to doQuickOperation().
 712          *
 713          * @see FileBackend::doQuickOperation()
 714          *
 715          * @param array $params Operation parameters
 716          * @return Status
 717          * @since 1.21
 718          */
 719         final public function quickDescribe( array $params ) {
 720                 return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
 721         }
 722
 723         /**
 724          * Concatenate a list of storage files into a single file system file.
 725          * The target path should refer to a file that is already locked or
 726          * otherwise safe from modification from other processes. Normally,
 727          * the file will be a new temp file, which should be adequate.
 728          *
 729          * @param array $params Operation parameters, include:
 730          *   - srcs        : ordered source storage paths (e.g. chunk1, chunk2, ...)
 731          *   - dst         : file system path to 0-byte temp file
 732          *   - parallelize : try to do operations in parallel when possible
 733          * @return Status
 734          */
 735         abstract public function concatenate( array $params );
 736
 737         /**
 738          * Prepare a storage directory for usage.
 739          * This will create any required containers and parent directories.
 740          * Backends using key/value stores only need to create the container.
 741          *
 742          * The 'noAccess' and 'noListing' parameters works the same as in secure(),
 743          * except they are only applied *if* the directory/container had to be created.
 744          * These flags should always be set for directories that have private files.
 745          * However, setting them is not guaranteed to actually do anything.
 746          * Additional server configuration may be needed to achieve the desired effect.
 747          *
 748          * @param array $params Parameters include:
 749          *   - dir            : storage directory
 750          *   - noAccess       : try to deny file access (since 1.20)
 751          *   - noListing      : try to deny file listing (since 1.20)
 752          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 753          * @return Status
 754          */
 755         final public function prepare( array $params ) {
 756                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 757                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 758                 }
 759                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 760                 return $this->doPrepare( $params );
 761         }
 762
 763         /**
 764          * @see FileBackend::prepare()
 765          */
 766         abstract protected function doPrepare( array $params );
 767
 768         /**
 769          * Take measures to block web access to a storage directory and
 770          * the container it belongs to. FS backends might add .htaccess
 771          * files whereas key/value store backends might revoke container
 772          * access to the storage user representing end-users in web requests.
 773          *
 774          * This is not guaranteed to actually make files or listings publically hidden.
 775          * Additional server configuration may be needed to achieve the desired effect.
 776          *
 777          * @param array $params Parameters include:
 778          *   - dir            : storage directory
 779          *   - noAccess       : try to deny file access
 780          *   - noListing      : try to deny file listing
 781          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 782          * @return Status
 783          */
 784         final public function secure( array $params ) {
 785                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 786                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 787                 }
 788                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 789                 return $this->doSecure( $params );
 790         }
 791
 792         /**
 793          * @see FileBackend::secure()
 794          */
 795         abstract protected function doSecure( array $params );
 796
 797         /**
 798          * Remove measures to block web access to a storage directory and
 799          * the container it belongs to. FS backends might remove .htaccess
 800          * files whereas key/value store backends might grant container
 801          * access to the storage user representing end-users in web requests.
 802          * This essentially can undo the result of secure() calls.
 803          *
 804          * This is not guaranteed to actually make files or listings publically viewable.
 805          * Additional server configuration may be needed to achieve the desired effect.
 806          *
 807          * @param array $params Parameters include:
 808          *   - dir            : storage directory
 809          *   - access         : try to allow file access
 810          *   - listing        : try to allow file listing
 811          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 812          * @return Status
 813          * @since 1.20
 814          */
 815         final public function publish( array $params ) {
 816                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 817                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 818                 }
 819                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 820                 return $this->doPublish( $params );
 821         }
 822
 823         /**
 824          * @see FileBackend::publish()
 825          */
 826         abstract protected function doPublish( array $params );
 827
 828         /**
 829          * Delete a storage directory if it is empty.
 830          * Backends using key/value stores may do nothing unless the directory
 831          * is that of an empty container, in which case it will be deleted.
 832          *
 833          * @param array $params Parameters include:
 834          *   - dir            : storage directory
 835          *   - recursive      : recursively delete empty subdirectories first (since 1.20)
 836          *   - bypassReadOnly : allow writes in read-only mode (since 1.20)
 837          * @return Status
 838          */
 839         final public function clean( array $params ) {
 840                 if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
 841                         return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
 842                 }
 843                 $scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
 844                 return $this->doClean( $params );
 845         }
 846
 847         /**
 848          * @see FileBackend::clean()
 849          */
 850         abstract protected function doClean( array $params );
 851
 852         /**
 853          * Enter file operation scope.
 854          * This just makes PHP ignore user aborts/disconnects until the return
 855          * value leaves scope. This returns null and does nothing in CLI mode.
 856          *
 857          * @return ScopedCallback|null
 858          */
 859         final protected function getScopedPHPBehaviorForOps() {
 860                 if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
 861                         $old = ignore_user_abort( true ); // avoid half-finished operations
 862                         return new ScopedCallback( function () use ( $old ) {
 863                                 ignore_user_abort( $old );
 864                         } );
 865                 }
 866
 867                 return null;
 868         }
 869
 870         /**
 871          * Check if a file exists at a storage path in the backend.
 872          * This returns false if only a directory exists at the path.
 873          *
 874          * @param array $params Parameters include:
 875          *   - src    : source storage path
 876          *   - latest : use the latest available data
 877          * @return bool|null Returns null on failure
 878          */
 879         abstract public function fileExists( array $params );
 880
 881         /**
 882          * Get the last-modified timestamp of the file at a storage path.
 883          *
 884          * @param array $params Parameters include:
 885          *   - src    : source storage path
 886          *   - latest : use the latest available data
 887          * @return string|bool TS_MW timestamp or false on failure
 888          */
 889         abstract public function getFileTimestamp( array $params );
 890
 891         /**
 892          * Get the contents of a file at a storage path in the backend.
 893          * This should be avoided for potentially large files.
 894          *
 895          * @param array $params Parameters include:
 896          *   - src    : source storage path
 897          *   - latest : use the latest available data
 898          * @return string|bool Returns false on failure
 899          */
 900         final public function getFileContents( array $params ) {
 901                 $contents = $this->getFileContentsMulti(
 902                         array( 'srcs' => array( $params['src'] ) ) + $params );
 903
 904                 return $contents[$params['src']];
 905         }
 906
 907         /**
 908          * Like getFileContents() except it takes an array of storage paths
 909          * and returns a map of storage paths to strings (or null on failure).
 910          * The map keys (paths) are in the same order as the provided list of paths.
 911          *
 912          * @see FileBackend::getFileContents()
 913          *
 914          * @param array $params Parameters include:
 915          *   - srcs        : list of source storage paths
 916          *   - latest      : use the latest available data
 917          *   - parallelize : try to do operations in parallel when possible
 918          * @return array Map of (path name => string or false on failure)
 919          * @since 1.20
 920          */
 921         abstract public function getFileContentsMulti( array $params );
 922
 923         /**
 924          * Get metadata about a file at a storage path in the backend.
 925          * If the file does not exist, then this returns false.
 926          * Otherwise, the result is an associative array that includes:
 927          *   - headers  : map of HTTP headers used for GET/HEAD requests (name => value)
 928          *   - metadata : map of file metadata (name => value)
 929          * Metadata keys and headers names will be returned in all lower-case.
 930          * Additional values may be included for internal use only.
 931          *
 932          * Use FileBackend::hasFeatures() to check how well this is supported.
 933          *
 934          * @param array $params
 935          * $params include:
 936          *   - src    : source storage path
 937          *   - latest : use the latest available data
 938          * @return array|bool Returns false on failure
 939          * @since 1.23
 940          */
 941         abstract public function getFileXAttributes( array $params );
 942
 943         /**
 944          * Get the size (bytes) of a file at a storage path in the backend.
 945          *
 946          * @param array $params Parameters include:
 947          *   - src    : source storage path
 948          *   - latest : use the latest available data
 949          * @return int|bool Returns false on failure
 950          */
 951         abstract public function getFileSize( array $params );
 952
 953         /**
 954          * Get quick information about a file at a storage path in the backend.
 955          * If the file does not exist, then this returns false.
 956          * Otherwise, the result is an associative array that includes:
 957          *   - mtime  : the last-modified timestamp (TS_MW)
 958          *   - size   : the file size (bytes)
 959          * Additional values may be included for internal use only.
 960          *
 961          * @param array $params Parameters include:
 962          *   - src    : source storage path
 963          *   - latest : use the latest available data
 964          * @return array|bool|null Returns null on failure
 965          */
 966         abstract public function getFileStat( array $params );
 967
 968         /**
 969          * Get a SHA-1 hash of the file at a storage path in the backend.
 970          *
 971          * @param array $params Parameters include:
 972          *   - src    : source storage path
 973          *   - latest : use the latest available data
 974          * @return string|bool Hash string or false on failure
 975          */
 976         abstract public function getFileSha1Base36( array $params );
 977
 978         /**
 979          * Get the properties of the file at a storage path in the backend.
 980          * This gives the result of FSFile::getProps() on a local copy of the file.
 981          *
 982          * @param array $params Parameters include:
 983          *   - src    : source storage path
 984          *   - latest : use the latest available data
 985          * @return array Returns FSFile::placeholderProps() on failure
 986          */
 987         abstract public function getFileProps( array $params );
 988
 989         /**
 990          * Stream the file at a storage path in the backend.
 991          * If the file does not exists, an HTTP 404 error will be given.
 992          * Appropriate HTTP headers (Status, Content-Type, Content-Length)
 993          * will be sent if streaming began, while none will be sent otherwise.
 994          * Implementations should flush the output buffer before sending data.
 995          *
 996          * @param array $params Parameters include:
 997          *   - src     : source storage path
 998          *   - headers : list of additional HTTP headers to send on success
 999          *   - latest  : use the latest available data
1000          * @return Status
1001          */
1002         abstract public function streamFile( array $params );
1003
1004         /**
1005          * Returns a file system file, identical to the file at a storage path.
1006          * The file returned is either:
1007          *   - a) A local copy of the file at a storage path in the backend.
1008          *        The temporary copy will have the same extension as the source.
1009          *   - b) An original of the file at a storage path in the backend.
1010          * Temporary files may be purged when the file object falls out of scope.
1011          *
1012          * Write operations should *never* be done on this file as some backends
1013          * may do internal tracking or may be instances of FileBackendMultiWrite.
1014          * In that later case, there are copies of the file that must stay in sync.
1015          * Additionally, further calls to this function may return the same file.
1016          *
1017          * @param array $params Parameters include:
1018          *   - src    : source storage path
1019          *   - latest : use the latest available data
1020          * @return FSFile|null Returns null on failure
1021          */
1022         final public function getLocalReference( array $params ) {
1023                 $fsFiles = $this->getLocalReferenceMulti(
1024                         array( 'srcs' => array( $params['src'] ) ) + $params );
1025
1026                 return $fsFiles[$params['src']];
1027         }
1028
1029         /**
1030          * Like getLocalReference() except it takes an array of storage paths
1031          * and returns a map of storage paths to FSFile objects (or null on failure).
1032          * The map keys (paths) are in the same order as the provided list of paths.
1033          *
1034          * @see FileBackend::getLocalReference()
1035          *
1036          * @param array $params Parameters include:
1037          *   - srcs        : list of source storage paths
1038          *   - latest      : use the latest available data
1039          *   - parallelize : try to do operations in parallel when possible
1040          * @return array Map of (path name => FSFile or null on failure)
1041          * @since 1.20
1042          */
1043         abstract public function getLocalReferenceMulti( array $params );
1044
1045         /**
1046          * Get a local copy on disk of the file at a storage path in the backend.
1047          * The temporary copy will have the same file extension as the source.
1048          * Temporary files may be purged when the file object falls out of scope.
1049          *
1050          * @param array $params Parameters include:
1051          *   - src    : source storage path
1052          *   - latest : use the latest available data
1053          * @return TempFSFile|null Returns null on failure
1054          */
1055         final public function getLocalCopy( array $params ) {
1056                 $tmpFiles = $this->getLocalCopyMulti(
1057                         array( 'srcs' => array( $params['src'] ) ) + $params );
1058
1059                 return $tmpFiles[$params['src']];
1060         }
1061
1062         /**
1063          * Like getLocalCopy() except it takes an array of storage paths and
1064          * returns a map of storage paths to TempFSFile objects (or null on failure).
1065          * The map keys (paths) are in the same order as the provided list of paths.
1066          *
1067          * @see FileBackend::getLocalCopy()
1068          *
1069          * @param array $params Parameters include:
1070          *   - srcs        : list of source storage paths
1071          *   - latest      : use the latest available data
1072          *   - parallelize : try to do operations in parallel when possible
1073          * @return array Map of (path name => TempFSFile or null on failure)
1074          * @since 1.20
1075          */
1076         abstract public function getLocalCopyMulti( array $params );
1077
1078         /**
1079          * Return an HTTP URL to a given file that requires no authentication to use.
1080          * The URL may be pre-authenticated (via some token in the URL) and temporary.
1081          * This will return null if the backend cannot make an HTTP URL for the file.
1082          *
1083          * This is useful for key/value stores when using scripts that seek around
1084          * large files and those scripts (and the backend) support HTTP Range headers.
1085          * Otherwise, one would need to use getLocalReference(), which involves loading
1086          * the entire file on to local disk.
1087          *
1088          * @param array $params Parameters include:
1089          *   - src : source storage path
1090          *   - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
1091          * @return string|null
1092          * @since 1.21
1093          */
1094         abstract public function getFileHttpUrl( array $params );
1095
1096         /**
1097          * Check if a directory exists at a given storage path.
1098          * Backends using key/value stores will check if the path is a
1099          * virtual directory, meaning there are files under the given directory.
1100          *
1101          * Storage backends with eventual consistency might return stale data.
1102          *
1103          * @param array $params Parameters include:
1104          *   - dir : storage directory
1105          * @return bool|null Returns null on failure
1106          * @since 1.20
1107          */
1108         abstract public function directoryExists( array $params );
1109
1110         /**
1111          * Get an iterator to list *all* directories under a storage directory.
1112          * If the directory is of the form "mwstore://backend/container",
1113          * then all directories in the container will be listed.
1114          * If the directory is of form "mwstore://backend/container/dir",
1115          * then all directories directly under that directory will be listed.
1116          * Results will be storage directories relative to the given directory.
1117          *
1118          * Storage backends with eventual consistency might return stale data.
1119          *
1120          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1121          *
1122          * @param array $params Parameters include:
1123          *   - dir     : storage directory
1124          *   - topOnly : only return direct child dirs of the directory
1125          * @return Traversable|array|null Returns null on failure
1126          * @since 1.20
1127          */
1128         abstract public function getDirectoryList( array $params );
1129
1130         /**
1131          * Same as FileBackend::getDirectoryList() except only lists
1132          * directories that are immediately under the given directory.
1133          *
1134          * Storage backends with eventual consistency might return stale data.
1135          *
1136          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1137          *
1138          * @param array $params Parameters include:
1139          *   - dir : storage directory
1140          * @return Traversable|array|null Returns null on failure
1141          * @since 1.20
1142          */
1143         final public function getTopDirectoryList( array $params ) {
1144                 return $this->getDirectoryList( array( 'topOnly' => true ) + $params );
1145         }
1146
1147         /**
1148          * Get an iterator to list *all* stored files under a storage directory.
1149          * If the directory is of the form "mwstore://backend/container",
1150          * then all files in the container will be listed.
1151          * If the directory is of form "mwstore://backend/container/dir",
1152          * then all files under that directory will be listed.
1153          * Results will be storage paths relative to the given directory.
1154          *
1155          * Storage backends with eventual consistency might return stale data.
1156          *
1157          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1158          *
1159          * @param array $params Parameters include:
1160          *   - dir        : storage directory
1161          *   - topOnly    : only return direct child files of the directory (since 1.20)
1162          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1163          * @return Traversable|array|null Returns null on failure
1164          */
1165         abstract public function getFileList( array $params );
1166
1167         /**
1168          * Same as FileBackend::getFileList() except only lists
1169          * files that are immediately under the given directory.
1170          *
1171          * Storage backends with eventual consistency might return stale data.
1172          *
1173          * Failures during iteration can result in FileBackendError exceptions (since 1.22).
1174          *
1175          * @param array $params Parameters include:
1176          *   - dir        : storage directory
1177          *   - adviseStat : set to true if stat requests will be made on the files (since 1.22)
1178          * @return Traversable|array|null Returns null on failure
1179          * @since 1.20
1180          */
1181         final public function getTopFileList( array $params ) {
1182                 return $this->getFileList( array( 'topOnly' => true ) + $params );
1183         }
1184
1185         /**
1186          * Preload persistent file stat cache and property cache into in-process cache.
1187          * This should be used when stat calls will be made on a known list of a many files.
1188          *
1189          * @see FileBackend::getFileStat()
1190          *
1191          * @param array $paths Storage paths
1192          */
1193         abstract public function preloadCache( array $paths );
1194
1195         /**
1196          * Invalidate any in-process file stat and property cache.
1197          * If $paths is given, then only the cache for those files will be cleared.
1198          *
1199          * @see FileBackend::getFileStat()
1200          *
1201          * @param array $paths Storage paths (optional)
1202          */
1203         abstract public function clearCache( array $paths = null );
1204
1205         /**
1206          * Preload file stat information (concurrently if possible) into in-process cache.
1207          *
1208          * This should be used when stat calls will be made on a known list of a many files.
1209          * This does not make use of the persistent file stat cache.
1210          *
1211          * @see FileBackend::getFileStat()
1212          *
1213          * @param array $params Parameters include:
1214          *   - srcs        : list of source storage paths
1215          *   - latest      : use the latest available data
1216          * @return bool All requests proceeded without I/O errors (since 1.24)
1217          * @since 1.23
1218          */
1219         abstract public function preloadFileStat( array $params );
1220
1221         /**
1222          * Lock the files at the given storage paths in the backend.
1223          * This will either lock all the files or none (on failure).
1224          *
1225          * Callers should consider using getScopedFileLocks() instead.
1226          *
1227          * @param array $paths Storage paths
1228          * @param int $type LockManager::LOCK_* constant
1229          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1230          * @return Status
1231          */
1232         final public function lockFiles( array $paths, $type, $timeout = 0 ) {
1233                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1234
1235                 return $this->lockManager->lock( $paths, $type, $timeout );
1236         }
1237
1238         /**
1239          * Unlock the files at the given storage paths in the backend.
1240          *
1241          * @param array $paths Storage paths
1242          * @param int $type LockManager::LOCK_* constant
1243          * @return Status
1244          */
1245         final public function unlockFiles( array $paths, $type ) {
1246                 $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1247
1248                 return $this->lockManager->unlock( $paths, $type );
1249         }
1250
1251         /**
1252          * Lock the files at the given storage paths in the backend.
1253          * This will either lock all the files or none (on failure).
1254          * On failure, the status object will be updated with errors.
1255          *
1256          * Once the return value goes out scope, the locks will be released and
1257          * the status updated. Unlock fatals will not change the status "OK" value.
1258          *
1259          * @see ScopedLock::factory()
1260          *
1261          * @param array $paths List of storage paths or map of lock types to path lists
1262          * @param int|string $type LockManager::LOCK_* constant or "mixed"
1263          * @param Status $status Status to update on lock/unlock
1264          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
1265          * @return ScopedLock|null Returns null on failure
1266          */
1267         final public function getScopedFileLocks( array $paths, $type, Status $status, $timeout = 0 ) {
1268                 if ( $type === 'mixed' ) {
1269                         foreach ( $paths as &$typePaths ) {
1270                                 $typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
1271                         }
1272                 } else {
1273                         $paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
1274                 }
1275
1276                 return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
1277         }
1278
1279         /**
1280          * Get an array of scoped locks needed for a batch of file operations.
1281          *
1282          * Normally, FileBackend::doOperations() handles locking, unless
1283          * the 'nonLocking' param is passed in. This function is useful if you
1284          * want the files to be locked for a broader scope than just when the
1285          * files are changing. For example, if you need to update DB metadata,
1286          * you may want to keep the files locked until finished.
1287          *
1288          * @see FileBackend::doOperations()
1289          *
1290          * @param array $ops List of file operations to FileBackend::doOperations()
1291          * @param Status $status Status to update on lock/unlock
1292          * @return array List of ScopedFileLocks or null values
1293          * @since 1.20
1294          */
1295         abstract public function getScopedLocksForOps( array $ops, Status $status );
1296
1297         /**
1298          * Get the root storage path of this backend.
1299          * All container paths are "subdirectories" of this path.
1300          *
1301          * @return string Storage path
1302          * @since 1.20
1303          */
1304         final public function getRootStoragePath() {
1305                 return "mwstore://{$this->name}";
1306         }
1307
1308         /**
1309          * Get the storage path for the given container for this backend
1310          *
1311          * @param string $container Container name
1312          * @return string Storage path
1313          * @since 1.21
1314          */
1315         final public function getContainerStoragePath( $container ) {
1316                 return $this->getRootStoragePath() . "/{$container}";
1317         }
1318
1319         /**
1320          * Get the file journal object for this backend
1321          *
1322          * @return FileJournal
1323          */
1324         final public function getJournal() {
1325                 return $this->fileJournal;
1326         }
1327
1328         /**
1329          * Check if a given path is a "mwstore://" path.
1330          * This does not do any further validation or any existence checks.
1331          *
1332          * @param string $path
1333          * @return bool
1334          */
1335         final public static function isStoragePath( $path ) {
1336                 return ( strpos( $path, 'mwstore://' ) === 0 );
1337         }
1338
1339         /**
1340          * Split a storage path into a backend name, a container name,
1341          * and a relative file path. The relative path may be the empty string.
1342          * This does not do any path normalization or traversal checks.
1343          *
1344          * @param string $storagePath
1345          * @return array (backend, container, rel object) or (null, null, null)
1346          */
1347         final public static function splitStoragePath( $storagePath ) {
1348                 if ( self::isStoragePath( $storagePath ) ) {
1349                         // Remove the "mwstore://" prefix and split the path
1350                         $parts = explode( '/', substr( $storagePath, 10 ), 3 );
1351                         if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
1352                                 if ( count( $parts ) == 3 ) {
1353                                         return $parts; // e.g. "backend/container/path"
1354                                 } else {
1355                                         return array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
1356                                 }
1357                         }
1358                 }
1359
1360                 return array( null, null, null );
1361         }
1362
1363         /**
1364          * Normalize a storage path by cleaning up directory separators.
1365          * Returns null if the path is not of the format of a valid storage path.
1366          *
1367          * @param string $storagePath
1368          * @return string|null
1369          */
1370         final public static function normalizeStoragePath( $storagePath ) {
1371                 list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath );
1372                 if ( $relPath !== null ) { // must be for this backend
1373                         $relPath = self::normalizeContainerPath( $relPath );
1374                         if ( $relPath !== null ) {
1375                                 return ( $relPath != '' )
1376                                         ? "mwstore://{$backend}/{$container}/{$relPath}"
1377                                         : "mwstore://{$backend}/{$container}";
1378                         }
1379                 }
1380
1381                 return null;
1382         }
1383
1384         /**
1385          * Get the parent storage directory of a storage path.
1386          * This returns a path like "mwstore://backend/container",
1387          * "mwstore://backend/container/...", or null if there is no parent.
1388          *
1389          * @param string $storagePath
1390          * @return string|null
1391          */
1392         final public static function parentStoragePath( $storagePath ) {
1393                 $storagePath = dirname( $storagePath );
1394                 list( , , $rel ) = self::splitStoragePath( $storagePath );
1395
1396                 return ( $rel === null ) ? null : $storagePath;
1397         }
1398
1399         /**
1400          * Get the final extension from a storage or FS path
1401          *
1402          * @param string $path
1403          * @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
1404          * @return string
1405          */
1406         final public static function extensionFromPath( $path, $case = 'lowercase' ) {
1407                 $i = strrpos( $path, '.' );
1408                 $ext = $i ? substr( $path, $i + 1 ) : '';
1409
1410                 if ( $case === 'lowercase' ) {
1411                         $ext = strtolower( $ext );
1412                 } elseif ( $case === 'uppercase' ) {
1413                         $ext = strtoupper( $ext );
1414                 }
1415
1416                 return $ext;
1417         }
1418
1419         /**
1420          * Check if a relative path has no directory traversals
1421          *
1422          * @param string $path
1423          * @return bool
1424          * @since 1.20
1425          */
1426         final public static function isPathTraversalFree( $path ) {
1427                 return ( self::normalizeContainerPath( $path ) !== null );
1428         }
1429
1430         /**
1431          * Build a Content-Disposition header value per RFC 6266.
1432          *
1433          * @param string $type One of (attachment, inline)
1434          * @param string $filename Suggested file name (should not contain slashes)
1435          * @throws FileBackendError
1436          * @return string
1437          * @since 1.20
1438          */
1439         final public static function makeContentDisposition( $type, $filename = '' ) {
1440                 $parts = array();
1441
1442                 $type = strtolower( $type );
1443                 if ( !in_array( $type, array( 'inline', 'attachment' ) ) ) {
1444                         throw new FileBackendError( "Invalid Content-Disposition type '$type'." );
1445                 }
1446                 $parts[] = $type;
1447
1448                 if ( strlen( $filename ) ) {
1449                         $parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
1450                 }
1451
1452                 return implode( ';', $parts );
1453         }
1454
1455         /**
1456          * Validate and normalize a relative storage path.
1457          * Null is returned if the path involves directory traversal.
1458          * Traversal is insecure for FS backends and broken for others.
1459          *
1460          * This uses the same traversal protection as Title::secureAndSplit().
1461          *
1462          * @param string $path Storage path relative to a container
1463          * @return string|null
1464          */
1465         final protected static function normalizeContainerPath( $path ) {
1466                 // Normalize directory separators
1467                 $path = strtr( $path, '\\', '/' );
1468                 // Collapse any consecutive directory separators
1469                 $path = preg_replace( '![/]{2,}!', '/', $path );
1470                 // Remove any leading directory separator
1471                 $path = ltrim( $path, '/' );
1472                 // Use the same traversal protection as Title::secureAndSplit()
1473                 if ( strpos( $path, '.' ) !== false ) {
1474                         if (
1475                                 $path === '.' ||
1476                                 $path === '..' ||
1477                                 strpos( $path, './' ) === 0 ||
1478                                 strpos( $path, '../' ) === 0 ||
1479                                 strpos( $path, '/./' ) !== false ||
1480                                 strpos( $path, '/../' ) !== false
1481                         ) {
1482                                 return null;
1483                         }
1484                 }
1485
1486                 return $path;
1487         }
1488 }
1489
1490 /**
1491  * Generic file backend exception for checked and unexpected (e.g. config) exceptions
1492  *
1493  * @ingroup FileBackend
1494  * @since 1.23
1495  */
1496 class FileBackendException extends Exception {
1497 }
1498
1499 /**
1500  * File backend exception for checked exceptions (e.g. I/O errors)
1501  *
1502  * @ingroup FileBackend
1503  * @since 1.22
1504  */
1505 class FileBackendError extends FileBackendException {
1506 }