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