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