FileBackend.php
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FileBackend.php
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	<?php
	/**
	* @defgroup FileBackend File backend
	*
	* File backend is used to interact with file storage systems,
	* such as the local file system, NFS, or cloud storage systems.
	* See [the architecture doc](@ref filebackendarch) for more information.
	*/

	/**
	* Base class for all file backends.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
	* http://www.gnu.org/copyleft/gpl.html
	*
	* @file
	* @ingroup FileBackend
	*/

	namespace Wikimedia\FileBackend;

	use InvalidArgumentException;
	use LockManager;
	use MediaWiki\FileBackend\FSFile\TempFSFileFactory;
	use NullLockManager;
	use Psr\Log\LoggerAwareInterface;
	use Psr\Log\LoggerInterface;
	use Psr\Log\NullLogger;
	use ScopedLock;
	use Shellbox\Command\BoxedCommand;
	use StatusValue;
	use Wikimedia\FileBackend\FSFile\FSFile;
	use Wikimedia\FileBackend\FSFile\TempFSFile;
	use Wikimedia\ScopedCallback;

	/**
	* @brief Base class for all file backend classes (including multi-write backends).
	*
	* This class defines the methods as abstract that subclasses must implement.
	* Outside callers can assume that all backends will have these functions.
	*
	* All "storage paths" are of the format "mwstore://<backend>/<container>/<path>".
	* The "backend" portion is unique name for the application to refer to a backend, while
	* the "container" portion is a top-level directory of the backend. The "path" portion
	* is a relative path that uses UNIX file system (FS) notation, though any particular
	* backend may not actually be using a local filesystem. Therefore, the relative paths
	* are only virtual.
	*
	* Backend contents are stored under "domain"-specific container names by default.
	* A domain is simply a logical umbrella for entities, such as those belonging to a certain
	* application or portion of a website, for example. A domain can be local or global.
	* Global (qualified) backends are achieved by configuring the "domain ID" to a constant.
	* Global domains are simpler, but local domains can be used by choosing a domain ID based on
	* the current context, such as which language of a website is being used.
	*
	* For legacy reasons, the FSFileBackend class allows manually setting the paths of
	* containers to ones that do not respect the "domain ID".
	*
	* In key/value (object) stores, containers are the only hierarchy (the rest is emulated).
	* FS-based backends are somewhat more restrictive due to the existence of real
	* directory files; a regular file cannot have the same name as a directory. Other
	* backends with virtual directories may not have this limitation. Callers should
	* store files in such a way that no files and directories are under the same path.
	*
	* In general, this class allows for callers to access storage through the same
	* interface, without regard to the underlying storage system. However, calling code
	* must follow certain patterns and be aware of certain things to ensure compatibility:
	* - a) Always call prepare() on the parent directory before trying to put a file there;
	* key/value stores only need the container to exist first, but filesystems need
	* all the parent directories to exist first (prepare() is aware of all this)
	* - b) Always call clean() on a directory when it might become empty to avoid empty
	* directory buildup on filesystems; key/value stores never have empty directories,
	* so doing this helps preserve consistency in both cases
	* - c) Likewise, do not rely on the existence of empty directories for anything;
	* calling directoryExists() on a path that prepare() was previously called on
	* will return false for key/value stores if there are no files under that path
	* - d) Never alter the resulting FSFile returned from getLocalReference(), as it could
	* either be a copy of the source file in /tmp or the original source file itself
	* - e) Use a file layout that results in never attempting to store files over directories
	* or directories over files; key/value stores allow this but filesystems do not
	* - f) Use ASCII file names (e.g. base32, IDs, hashes) to avoid Unicode issues in Windows
	* - g) Do not assume that move operations are atomic (difficult with key/value stores)
	* - h) Do not assume that file stat or read operations always have immediate consistency;
	* various methods have a "latest" flag that should always be used if up-to-date
	* information is required (this trades performance for correctness as needed)
	* - i) Do not assume that directory listings have immediate consistency
	*
	* Methods of subclasses should avoid throwing exceptions at all costs.
	* As a corollary, external dependencies should be kept to a minimum.
	*
	* See [the architecture doc](@ref filebackendarch) for more information.
	*
	* @stable to extend
	*
	* @ingroup FileBackend
	* @since 1.19
	*/
	abstract class FileBackend implements LoggerAwareInterface {
	/** @var string Unique backend name */
	protected $name;

	/** @var string Unique domain name */
	protected $domainId;

	/** @var string Read-only explanation message */
	protected $readOnly;

	/** @var string When to do operations in parallel */
	protected $parallelize;

	/** @var int How many operations can be done in parallel */
	protected $concurrency;

	/** @var TempFSFileFactory */
	protected $tmpFileFactory;

	/** @var LockManager */
	protected $lockManager;
	/** @var LoggerInterface */
	protected $logger;
	/** @var callable\|null */
	protected $profiler;

	/** @var callable */
	private $obResetFunc;
	/** @var callable */
	private $headerFunc;
	/** @var array Option map for use with HTTPFileStreamer */
	protected $streamerOptions;
	/** @var callable\|null */
	protected $statusWrapper;

	/** Bitfield flags for supported features */
	public const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
	public const ATTR_METADATA = 2; // files can be stored with metadata key/values
	public const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)

	/** @var false Idiom for "no info; non-existant file" (since 1.34) */
	protected const STAT_ABSENT = false;

	/** @var null Idiom for "no info; I/O errors" (since 1.34) */
	public const STAT_ERROR = null;
	/** @var null Idiom for "no file/directory list; I/O errors" (since 1.34) */
	public const LIST_ERROR = null;
	/** @var null Idiom for "no temp URL; not supported or I/O errors" (since 1.34) */
	public const TEMPURL_ERROR = null;
	/** @var null Idiom for "existence unknown; I/O errors" (since 1.34) */
	public const EXISTENCE_ERROR = null;

	/** @var false Idiom for "no timestamp; missing file or I/O errors" (since 1.34) */
	public const TIMESTAMP_FAIL = false;
	/** @var false Idiom for "no content; missing file or I/O errors" (since 1.34) */
	public const CONTENT_FAIL = false;
	/** @var false Idiom for "no metadata; missing file or I/O errors" (since 1.34) */
	public const XATTRS_FAIL = false;
	/** @var false Idiom for "no size; missing file or I/O errors" (since 1.34) */
	public const SIZE_FAIL = false;
	/** @var false Idiom for "no SHA1 hash; missing file or I/O errors" (since 1.34) */
	public const SHA1_FAIL = false;

	/**
	* Create a new backend instance from configuration.
	* This should only be called from within FileBackendGroup.
	* @stable to call
	*
	* @param array $config Parameters include:
	* - name : The unique name of this backend.
	* This should consist of alphanumberic, '-', and '_' characters.
	* This name should not be changed after use.
	* Note that the name is not used in actual container names.
	* - domainId : Prefix to container names that is unique to this backend.
	* It should only consist of alphanumberic, '-', and '_' characters.
	* This ID is what avoids collisions if multiple logical backends
	* use the same storage system, so this should be set carefully.
	* - lockManager : LockManager object to use for any file locking.
	* If not provided, then no file locking will be enforced.
	* - readOnly : Write operations are disallowed if this is a non-empty string.
	* It should be an explanation for the backend being read-only.
	* - parallelize : When to do file operations in parallel (when possible).
	* Allowed values are "implicit", "explicit" and "off".
	* - concurrency : How many file operations can be done in parallel.
	* - tmpDirectory : Directory to use for temporary files.
	* - tmpFileFactory : Optional TempFSFileFactory object. Only has an effect if
	* tmpDirectory is not set. If both are unset or null, then the backend will
	* try to discover a usable temporary directory.
	* - obResetFunc : alternative callback to clear the output buffer
	* - streamMimeFunc : alternative method to determine the content type from the path
	* - headerFunc : alternative callback for sending response headers
	* - logger : Optional PSR logger object.
	* - profiler : Optional callback that takes a section name argument and returns
	* a ScopedCallback instance that ends the profile section in its destructor.
	* - statusWrapper : Optional callback that is used to wrap returned StatusValues
	*/
	public function __construct( array $config ) {
	if ( !array_key_exists( 'name', $config ) ) {
	throw new InvalidArgumentException( 'Backend name not specified.' );
	}
	$this->name = $config['name'];
	$this->domainId = $config['domainId'] // e.g. "my_wiki-en_"
	?? $config['wikiId'] // b/c alias
	?? null;
	if ( !is_string( $this->name ) \|\| !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
	throw new InvalidArgumentException( "Backend name '{$this->name}' is invalid." );
	}
	if ( !is_string( $this->domainId ) ) {
	throw new InvalidArgumentException(
	"Backend domain ID not provided for '{$this->name}'." );
	}
	$this->lockManager = $config['lockManager'] ?? new NullLockManager( [] );
	$this->readOnly = isset( $config['readOnly'] )
	? (string)$config['readOnly']
	: '';
	$this->parallelize = isset( $config['parallelize'] )
	? (string)$config['parallelize']
	: 'off';
	$this->concurrency = isset( $config['concurrency'] )
	? (int)$config['concurrency']
	: 50;
	$this->obResetFunc = $config['obResetFunc']
	?? [ self::class, 'resetOutputBufferTheDefaultWay' ];
	$this->headerFunc = $config['headerFunc'] ?? 'header';
	$this->streamerOptions = [
	'obResetFunc' => $this->obResetFunc,
	'headerFunc' => $this->headerFunc,
	'streamMimeFunc' => $config['streamMimeFunc'] ?? null,
	];

	$this->profiler = $config['profiler'] ?? null;
	if ( !is_callable( $this->profiler ) ) {
	$this->profiler = null;
	}
	$this->logger = $config['logger'] ?? new NullLogger();
	$this->statusWrapper = $config['statusWrapper'] ?? null;
	// tmpDirectory gets precedence for backward compatibility
	if ( isset( $config['tmpDirectory'] ) ) {
	$this->tmpFileFactory = new TempFSFileFactory( $config['tmpDirectory'] );
	} else {
	$this->tmpFileFactory = $config['tmpFileFactory'] ?? new TempFSFileFactory();
	}
	}

	protected function header( $header ) {
	( $this->headerFunc )( $header );
	}

	protected function resetOutputBuffer() {
	// By default, this ends up calling $this->defaultOutputBufferReset
	( $this->obResetFunc )();
	}

	public function setLogger( LoggerInterface $logger ) {
	$this->logger = $logger;
	}

	/**
	* Get the unique backend name
	*
	* We may have multiple different backends of the same type.
	* For example, we can have two Swift backends using different proxies.
	*
	* @return string
	*/
	final public function getName() {
	return $this->name;
	}

	/**
	* Get the domain identifier used for this backend (possibly empty).
	*
	* @return string
	* @since 1.28
	*/
	final public function getDomainId() {
	return $this->domainId;
	}

	/**
	* Alias to getDomainId()
	*
	* @return string
	* @since 1.20
	* @deprecated Since 1.34 Use getDomainId()
	*/
	final public function getWikiId() {
	return $this->getDomainId();
	}

	/**
	* Check if this backend is read-only
	*
	* @return bool
	*/
	final public function isReadOnly() {
	return ( $this->readOnly != '' );
	}

	/**
	* Get an explanatory message if this backend is read-only
	*
	* @return string\|bool Returns false if the backend is not read-only
	*/
	final public function getReadOnlyReason() {
	return ( $this->readOnly != '' ) ? $this->readOnly : false;
	}

	/**
	* Get the a bitfield of extra features supported by the backend medium
	* @stable to override
	*
	* @return int Bitfield of FileBackend::ATTR_* flags
	* @since 1.23
	*/
	public function getFeatures() {
	return self::ATTR_UNICODE_PATHS;
	}

	/**
	* Check if the backend medium supports a field of extra features
	*
	* @param int $bitfield Bitfield of FileBackend::ATTR_* flags
	* @return bool
	* @since 1.23
	*/
	final public function hasFeatures( $bitfield ) {
	return ( $this->getFeatures() & $bitfield ) === $bitfield;
	}

	/**
	* This is the main entry point into the backend for write operations.
	* Callers supply an ordered list of operations to perform as a transaction.
	* Files will be locked, the stat cache cleared, and then the operations attempted.
	* If any serious errors occur, all attempted operations will be rolled back.
	*
	* $ops is an array of arrays. The outer array holds a list of operations.
	* Each inner array is a set of key value pairs that specify an operation.
	*
	* Supported operations and their parameters. The supported actions are:
	* - create
	* - store
	* - copy
	* - move
	* - delete
	* - describe (since 1.21)
	* - null
	*
	* FSFile/TempFSFile object support was added in 1.27.
	*
	* a) Create a new file in storage with the contents of a string
	* @code
	* [
	* 'op' => 'create',
	* 'dst' => <storage path>,
	* 'content' => <string of new file contents>,
	* 'overwrite' => <boolean>,
	* 'overwriteSame' => <boolean>,
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* b) Copy a file system file into storage
	* @code
	* [
	* 'op' => 'store',
	* 'src' => <file system path, FSFile, or TempFSFile>,
	* 'dst' => <storage path>,
	* 'overwrite' => <boolean>,
	* 'overwriteSame' => <boolean>,
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* c) Copy a file within storage
	* @code
	* [
	* 'op' => 'copy',
	* 'src' => <storage path>,
	* 'dst' => <storage path>,
	* 'overwrite' => <boolean>,
	* 'overwriteSame' => <boolean>,
	* 'ignoreMissingSource' => <boolean>, # since 1.21
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* d) Move a file within storage
	* @code
	* [
	* 'op' => 'move',
	* 'src' => <storage path>,
	* 'dst' => <storage path>,
	* 'overwrite' => <boolean>,
	* 'overwriteSame' => <boolean>,
	* 'ignoreMissingSource' => <boolean>, # since 1.21
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* e) Delete a file within storage
	* @code
	* [
	* 'op' => 'delete',
	* 'src' => <storage path>,
	* 'ignoreMissingSource' => <boolean>
	* ]
	* @endcode
	*
	* f) Update metadata for a file within storage
	* @code
	* [
	* 'op' => 'describe',
	* 'src' => <storage path>,
	* 'headers' => <HTTP header name/value map>
	* ]
	* @endcode
	*
	* g) Do nothing (no-op)
	* @code
	* [
	* 'op' => 'null',
	* ]
	* @endcode
	*
	* Boolean flags for operations (operation-specific):
	* - ignoreMissingSource : The operation will simply succeed and do
	* nothing if the source file does not exist.
	* - overwrite : Any destination file will be overwritten.
	* - overwriteSame : If a file already exists at the destination with the
	* same contents, then do nothing to the destination file
	* instead of giving an error. This does not compare headers.
	* This option is ignored if 'overwrite' is already provided.
	* - headers : If supplied, the result of merging these headers with any
	* existing source file headers (replacing conflicting ones)
	* will be set as the destination file headers. Headers are
	* deleted if their value is set to the empty string. When a
	* file has headers they are included in responses to GET and
	* HEAD requests to the backing store for that file.
	* Header values should be no larger than 255 bytes, except for
	* Content-Disposition. The system might ignore or truncate any
	* headers that are too long to store (exact limits will vary).
	* Backends that don't support metadata ignore this. (since 1.21)
	*
	* $opts is an associative of boolean flags, including:
	* - force : Operation precondition errors no longer trigger an abort.
	* Any remaining operations are still attempted. Unexpected
	* failures may still cause remaining operations to be aborted.
	* - nonLocking : No locks are acquired for the operations.
	* This can increase performance for non-critical writes.
	* This has no effect unless the 'force' flag is set.
	* - parallelize : Try to do operations in parallel when possible.
	* - bypassReadOnly : Allow writes in read-only mode. (since 1.20)
	* - preserveCache : Don't clear the process cache before checking files.
	* This should only be used if all entries in the process
	* cache were added after the files were already locked. (since 1.20)
	*
	* @note Remarks on locking:
	* File system paths given to operations should refer to files that are
	* already locked or otherwise safe from modification from other processes.
	* Normally these files will be new temp files, which should be adequate.
	*
	* @par Return value:
	*
	* This returns a Status, which contains all warnings and fatals that occurred
	* during the operation. The 'failCount', 'successCount', and 'success' members
	* will reflect each operation attempted.
	*
	* The StatusValue will be "OK" unless:
	* - a) unexpected operation errors occurred (network partitions, disk full...)
	* - b) predicted operation errors occurred and 'force' was not set
	*
	* @param array[] $ops List of operations to execute in order
	* @phan-param array<int,array{ignoreMissingSource?:bool,overwrite?:bool,overwriteSame?:bool,headers?:bool}> $ops
	* @param array $opts Batch operation options
	* @phpcs:ignore Generic.Files.LineLength
	* @phan-param array{force?:bool,nonLocking?:bool,parallelize?:bool,bypassReadOnly?:bool,preserveCache?:bool} $opts
	* @return StatusValue
	*/
	final public function doOperations( array $ops, array $opts = [] ) {
	if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	if ( $ops === [] ) {
	return $this->newStatus(); // nothing to do
	}

	$ops = $this->resolveFSFileObjects( $ops );
	if ( empty( $opts['force'] ) ) {
	unset( $opts['nonLocking'] );
	}

	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts

	return $this->doOperationsInternal( $ops, $opts );
	}

	/**
	* @see FileBackend::doOperations()
	* @param array $ops
	* @param array $opts
	* @return StatusValue
	*/
	abstract protected function doOperationsInternal( array $ops, array $opts );

	/**
	* Same as doOperations() except it takes a single operation.
	* If you are doing a batch of operations that should either
	* all succeed or all fail, then use that function instead.
	*
	* @see FileBackend::doOperations()
	*
	* @param array $op Operation
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function doOperation( array $op, array $opts = [] ) {
	return $this->doOperations( [ $op ], $opts );
	}

	/**
	* Performs a single create operation.
	* This sets $params['op'] to 'create' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function create( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'create' ] + $params, $opts );
	}

	/**
	* Performs a single store operation.
	* This sets $params['op'] to 'store' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function store( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'store' ] + $params, $opts );
	}

	/**
	* Performs a single copy operation.
	* This sets $params['op'] to 'copy' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function copy( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'copy' ] + $params, $opts );
	}

	/**
	* Performs a single move operation.
	* This sets $params['op'] to 'move' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function move( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'move' ] + $params, $opts );
	}

	/**
	* Performs a single delete operation.
	* This sets $params['op'] to 'delete' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	*/
	final public function delete( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'delete' ] + $params, $opts );
	}

	/**
	* Performs a single describe operation.
	* This sets $params['op'] to 'describe' and passes it to doOperation().
	*
	* @see FileBackend::doOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.21
	*/
	final public function describe( array $params, array $opts = [] ) {
	return $this->doOperation( [ 'op' => 'describe' ] + $params, $opts );
	}

	/**
	* Perform a set of independent file operations on some files.
	*
	* This does no locking, and possibly no stat calls.
	* Any destination files that already exist will be overwritten.
	* This should only be used on non-original files, like cache files.
	*
	* Supported operations and their parameters:
	* - create
	* - store
	* - copy
	* - move
	* - delete
	* - describe (since 1.21)
	* - null
	*
	* FSFile/TempFSFile object support was added in 1.27.
	*
	* a) Create a new file in storage with the contents of a string
	* @code
	* [
	* 'op' => 'create',
	* 'dst' => <storage path>,
	* 'content' => <string of new file contents>,
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* b) Copy a file system file into storage
	* @code
	* [
	* 'op' => 'store',
	* 'src' => <file system path, FSFile, or TempFSFile>,
	* 'dst' => <storage path>,
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* c) Copy a file within storage
	* @code
	* [
	* 'op' => 'copy',
	* 'src' => <storage path>,
	* 'dst' => <storage path>,
	* 'ignoreMissingSource' => <boolean>, # since 1.21
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* d) Move a file within storage
	* @code
	* [
	* 'op' => 'move',
	* 'src' => <storage path>,
	* 'dst' => <storage path>,
	* 'ignoreMissingSource' => <boolean>, # since 1.21
	* 'headers' => <HTTP header name/value map> # since 1.21
	* ]
	* @endcode
	*
	* e) Delete a file within storage
	* @code
	* [
	* 'op' => 'delete',
	* 'src' => <storage path>,
	* 'ignoreMissingSource' => <boolean>
	* ]
	* @endcode
	*
	* f) Update metadata for a file within storage
	* @code
	* [
	* 'op' => 'describe',
	* 'src' => <storage path>,
	* 'headers' => <HTTP header name/value map>
	* ]
	* @endcode
	*
	* g) Do nothing (no-op)
	* @code
	* [
	* 'op' => 'null',
	* ]
	* @endcode
	*
	* @par Boolean flags for operations (operation-specific):
	* - ignoreMissingSource : The operation will simply succeed and do
	* nothing if the source file does not exist.
	* - headers : If supplied with a header name/value map, the backend will
	* reply with these headers when GETs/HEADs of the destination
	* file are made. Header values should be smaller than 256 bytes.
	* Content-Disposition headers can be longer, though the system
	* might ignore or truncate ones that are too long to store.
	* Existing headers will remain, but these will replace any
	* conflicting previous headers, and headers will be removed
	* if they are set to an empty string.
	* Backends that don't support metadata ignore this. (since 1.21)
	*
	* $opts is an associative of boolean flags, including:
	* - bypassReadOnly : Allow writes in read-only mode (since 1.20)
	*
	* @par Return value:
	* This returns a Status, which contains all warnings and fatals that occurred
	* during the operation. The 'failCount', 'successCount', and 'success' members
	* will reflect each operation attempted for the given files. The StatusValue will be
	* considered "OK" as long as no fatal errors occurred.
	*
	* @param array $ops Set of operations to execute
	* @phan-param list<array{op:?string,src?:string,dst?:string,ignoreMissingSource?:bool,headers?:array}> $ops
	* @param array $opts Batch operation options
	* @phan-param array{bypassReadOnly?:bool} $opts
	* @return StatusValue
	* @since 1.20
	*/
	final public function doQuickOperations( array $ops, array $opts = [] ) {
	if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	if ( $ops === [] ) {
	return $this->newStatus(); // nothing to do
	}

	$ops = $this->resolveFSFileObjects( $ops );
	foreach ( $ops as &$op ) {
	$op['overwrite'] = true; // avoids RTTs in key/value stores
	}

	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts

	return $this->doQuickOperationsInternal( $ops, $opts );
	}

	/**
	* @see FileBackend::doQuickOperations()
	* @param array $ops
	* @param array $opts
	* @return StatusValue
	* @since 1.20
	*/
	abstract protected function doQuickOperationsInternal( array $ops, array $opts );

	/**
	* Same as doQuickOperations() except it takes a single operation.
	* If you are doing a batch of operations, then use that function instead.
	*
	* @see FileBackend::doQuickOperations()
	*
	* @param array $op Operation
	* @param array $opts Batch operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function doQuickOperation( array $op, array $opts = [] ) {
	return $this->doQuickOperations( [ $op ], $opts );
	}

	/**
	* Performs a single quick create operation.
	* This sets $params['op'] to 'create' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function quickCreate( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'create' ] + $params, $opts );
	}

	/**
	* Performs a single quick store operation.
	* This sets $params['op'] to 'store' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function quickStore( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'store' ] + $params, $opts );
	}

	/**
	* Performs a single quick copy operation.
	* This sets $params['op'] to 'copy' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function quickCopy( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'copy' ] + $params, $opts );
	}

	/**
	* Performs a single quick move operation.
	* This sets $params['op'] to 'move' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function quickMove( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'move' ] + $params, $opts );
	}

	/**
	* Performs a single quick delete operation.
	* This sets $params['op'] to 'delete' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.20
	*/
	final public function quickDelete( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'delete' ] + $params, $opts );
	}

	/**
	* Performs a single quick describe operation.
	* This sets $params['op'] to 'describe' and passes it to doQuickOperation().
	*
	* @see FileBackend::doQuickOperation()
	*
	* @param array $params Operation parameters
	* @param array $opts Operation options
	* @return StatusValue
	* @since 1.21
	*/
	final public function quickDescribe( array $params, array $opts = [] ) {
	return $this->doQuickOperation( [ 'op' => 'describe' ] + $params, $opts );
	}

	/**
	* Concatenate a list of storage files into a single file system file.
	* The target path should refer to a file that is already locked or
	* otherwise safe from modification from other processes. Normally,
	* the file will be a new temp file, which should be adequate.
	*
	* @param array $params Operation parameters, include:
	* - srcs : ordered source storage paths (e.g. chunk1, chunk2, ...)
	* - dst : file system path to 0-byte temp file
	* - parallelize : try to do operations in parallel when possible
	* @return StatusValue
	*/
	abstract public function concatenate( array $params );

	/**
	* Prepare a storage directory for usage.
	* This will create any required containers and parent directories.
	* Backends using key/value stores only need to create the container.
	*
	* The 'noAccess' and 'noListing' parameters works the same as in secure(),
	* except they are only applied if the directory/container had to be created.
	* These flags should always be set for directories that have private files.
	* However, setting them is not guaranteed to actually do anything.
	* Additional server configuration may be needed to achieve the desired effect.
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - noAccess : try to deny file access (since 1.20)
	* - noListing : try to deny file listing (since 1.20)
	* - bypassReadOnly : allow writes in read-only mode (since 1.20)
	* @return StatusValue Good status without value for success, fatal otherwise.
	*/
	final public function prepare( array $params ) {
	if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
	return $this->doPrepare( $params );
	}

	/**
	* @see FileBackend::prepare()
	* @param array $params
	* @return StatusValue Good status without value for success, fatal otherwise.
	*/
	abstract protected function doPrepare( array $params );

	/**
	* Take measures to block web access to a storage directory and
	* the container it belongs to. FS backends might add .htaccess
	* files whereas key/value store backends might revoke container
	* access to the storage user representing end-users in web requests.
	*
	* This is not guaranteed to actually make files or listings publicly hidden.
	* Additional server configuration may be needed to achieve the desired effect.
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - noAccess : try to deny file access
	* - noListing : try to deny file listing
	* - bypassReadOnly : allow writes in read-only mode (since 1.20)
	* @return StatusValue
	*/
	final public function secure( array $params ) {
	if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
	return $this->doSecure( $params );
	}

	/**
	* @see FileBackend::secure()
	* @param array $params
	* @return StatusValue
	*/
	abstract protected function doSecure( array $params );

	/**
	* Remove measures to block web access to a storage directory and
	* the container it belongs to. FS backends might remove .htaccess
	* files whereas key/value store backends might grant container
	* access to the storage user representing end-users in web requests.
	* This essentially can undo the result of secure() calls.
	*
	* This is not guaranteed to actually make files or listings publicly viewable.
	* Additional server configuration may be needed to achieve the desired effect.
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - access : try to allow file access
	* - listing : try to allow file listing
	* - bypassReadOnly : allow writes in read-only mode (since 1.20)
	* @return StatusValue
	* @since 1.20
	*/
	final public function publish( array $params ) {
	if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
	return $this->doPublish( $params );
	}

	/**
	* @see FileBackend::publish()
	* @param array $params
	* @return StatusValue
	*/
	abstract protected function doPublish( array $params );

	/**
	* Delete a storage directory if it is empty.
	* Backends using key/value stores may do nothing unless the directory
	* is that of an empty container, in which case it will be deleted.
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - recursive : recursively delete empty subdirectories first (since 1.20)
	* - bypassReadOnly : allow writes in read-only mode (since 1.20)
	* @return StatusValue
	*/
	final public function clean( array $params ) {
	if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
	return $this->newStatus( 'backend-fail-readonly', $this->name, $this->readOnly );
	}
	/** @noinspection PhpUnusedLocalVariableInspection */
	$scope = ScopedCallback::newScopedIgnoreUserAbort(); // try to ignore client aborts
	return $this->doClean( $params );
	}

	/**
	* @see FileBackend::clean()
	* @param array $params
	* @return StatusValue
	*/
	abstract protected function doClean( array $params );

	/**
	* Check if a file exists at a storage path in the backend.
	* This returns false if only a directory exists at the path.
	*
	* Callers that only care if a file is readily accessible can use non-strict
	* comparisons on the result. If "does not exist" and "existence is unknown"
	* must be distinguished, then strict comparisons to true/null should be used.
	*
	* @see FileBackend::EXISTENCE_ERROR
	* @see FileBackend::directoryExists()
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return bool\|null Whether the file exists or null (I/O error)
	*/
	abstract public function fileExists( array $params );

	/**
	* Get the last-modified timestamp of the file at a storage path.
	*
	* @see FileBackend::TIMESTAMP_FAIL
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return string\|false TS_MW timestamp or false (missing file or I/O error)
	*/
	abstract public function getFileTimestamp( array $params );

	/**
	* Get the contents of a file at a storage path in the backend.
	* This should be avoided for potentially large files.
	*
	* @see FileBackend::CONTENT_FAIL
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return string\|false Content string or false (missing file or I/O error)
	*/
	final public function getFileContents( array $params ) {
	$contents = $this->getFileContentsMulti( [ 'srcs' => [ $params['src'] ] ] + $params );

	return $contents[$params['src']];
	}

	/**
	* Like getFileContents() except it takes an array of storage paths
	* and returns an order preserved map of storage paths to their content.
	*
	* @see FileBackend::getFileContents()
	*
	* @param array $params Parameters include:
	* - srcs : list of source storage paths
	* - latest : use the latest available data
	* - parallelize : try to do operations in parallel when possible
	* @return string[]\|false[] Map of (path name => file content or false on failure)
	* @since 1.20
	*/
	abstract public function getFileContentsMulti( array $params );

	/**
	* Get metadata about a file at a storage path in the backend.
	* If the file does not exist, then this returns false.
	* Otherwise, the result is an associative array that includes:
	* - headers : map of HTTP headers used for GET/HEAD requests (name => value)
	* - metadata : map of file metadata (name => value)
	* Metadata keys and headers names will be returned in all lower-case.
	* Additional values may be included for internal use only.
	*
	* Use FileBackend::hasFeatures() to check how well this is supported.
	*
	* @see FileBackend::XATTRS_FAIL
	*
	* @param array $params
	* $params include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return array\|false File metadata array or false (missing file or I/O error)
	* @since 1.23
	*/
	abstract public function getFileXAttributes( array $params );

	/**
	* Get the size (bytes) of a file at a storage path in the backend.
	*
	* @see FileBackend::SIZE_FAIL
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return int\|false File size in bytes or false (missing file or I/O error)
	*/
	abstract public function getFileSize( array $params );

	/**
	* Get quick information about a file at a storage path in the backend.
	* If the file does not exist, then this returns false.
	* Otherwise, the result is an associative array that includes:
	* - mtime : the last-modified timestamp (TS_MW)
	* - size : the file size (bytes)
	* Additional values may be included for internal use only.
	*
	* @see FileBackend::STAT_ABSENT
	* @see FileBackend::STAT_ERROR
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return array\|false\|null Attribute map, false (missing file), or null (I/O error)
	*/
	abstract public function getFileStat( array $params );

	/**
	* Get a SHA-1 hash of the content of the file at a storage path in the backend.
	*
	* @see FileBackend::SHA1_FAIL
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return string\|false Hash string or false (missing file or I/O error)
	*/
	abstract public function getFileSha1Base36( array $params );

	/**
	* Get the properties of the content of the file at a storage path in the backend.
	* This gives the result of FSFile::getProps() on a local copy of the file.
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return array Properties map; FSFile::placeholderProps() if file missing or on I/O error
	*/
	abstract public function getFileProps( array $params );

	/**
	* Stream the content of the file at a storage path in the backend.
	*
	* If the file does not exists, an HTTP 404 error will be given.
	* Appropriate HTTP headers (Status, Content-Type, Content-Length)
	* will be sent if streaming began, while none will be sent otherwise.
	* Implementations should flush the output buffer before sending data.
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - headers : list of additional HTTP headers to send if the file exists
	* - options : HTTP request header map with lower case keys (since 1.28). Supports:
	* range : format is "bytes=(\d-\d)"
	* if-modified-since : format is an HTTP date
	* - headless : do not send HTTP headers (including those of "headers") (since 1.28)
	* - latest : use the latest available data
	* - allowOB : preserve any output buffers (since 1.28)
	* @return StatusValue
	*/
	abstract public function streamFile( array $params );

	/**
	* Returns a file system file, identical in content to the file at a storage path.
	* The file returned is either:
	* - a) A TempFSFile local copy of the file at a storage path in the backend.
	* The temporary copy will have the same extension as the source.
	* Temporary files may be purged when the file object falls out of scope.
	* - b) An FSFile pointing to the original file at a storage path in the backend.
	* This is applicable for backends layered directly on top of file systems.
	*
	* Never modify the returned file since it might be the original, it might be shared
	* among multiple callers of this method, or the backend might internally keep FSFile
	* references for deferred operations.
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return FSFile\|null\|false Local file copy or false (missing) or null (error)
	*/
	final public function getLocalReference( array $params ) {
	$fsFiles = $this->getLocalReferenceMulti( [ 'srcs' => [ $params['src'] ] ] + $params );

	return $fsFiles[$params['src']];
	}

	/**
	* Like getLocalReference() except it takes an array of storage paths and
	* yields an order-preserved map of storage paths to temporary local file copies.
	*
	* Never modify the returned files since they might be originals, they might be shared
	* among multiple callers of this method, or the backend might internally keep FSFile
	* references for deferred operations.
	*
	* @see FileBackend::getLocalReference()
	*
	* @param array $params Parameters include:
	* - srcs : list of source storage paths
	* - latest : use the latest available data
	* - parallelize : try to do operations in parallel when possible
	* @return array Map of (path name => FSFile or false (missing) or null (error))
	* @since 1.20
	*/
	abstract public function getLocalReferenceMulti( array $params );

	/**
	* Get a local copy on disk of the file at a storage path in the backend.
	* The temporary copy will have the same file extension as the source.
	* Temporary files may be purged when the file object falls out of scope.
	*
	* Multiple calls to this method for the same path will create new copies.
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return TempFSFile\|null\|false Temporary local file copy or false (missing) or null (error)
	*/
	final public function getLocalCopy( array $params ) {
	$tmpFiles = $this->getLocalCopyMulti( [ 'srcs' => [ $params['src'] ] ] + $params );

	return $tmpFiles[$params['src']];
	}

	/**
	* Like getLocalCopy() except it takes an array of storage paths and yields
	* an order preserved-map of storage paths to temporary local file copies.
	*
	* Multiple calls to this method for the same path will create new copies.
	*
	* @see FileBackend::getLocalCopy()
	*
	* @param array $params Parameters include:
	* - srcs : list of source storage paths
	* - latest : use the latest available data
	* - parallelize : try to do operations in parallel when possible
	* @return array Map of (path name => TempFSFile or false (missing) or null (error))
	* @since 1.20
	*/
	abstract public function getLocalCopyMulti( array $params );

	/**
	* Return an HTTP URL to a given file that requires no authentication to use.
	* The URL may be pre-authenticated (via some token in the URL) and temporary.
	* This will return null if the backend cannot make an HTTP URL for the file.
	*
	* This is useful for key/value stores when using scripts that seek around
	* large files and those scripts (and the backend) support HTTP Range headers.
	* Otherwise, one would need to use getLocalReference(), which involves loading
	* the entire file on to local disk.
	*
	* @see FileBackend::TEMPURL_ERROR
	*
	* @param array $params Parameters include:
	* - src : source storage path
	* - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
	* - latest : use the latest available data
	* - method : the allowed method; default GET
	* - ipRange : the allowed IP range; default unlimited
	* @return string\|null URL or null (not supported or I/O error)
	* @since 1.21
	*/
	abstract public function getFileHttpUrl( array $params );

	/**
	* Add a file to a Shellbox command as an input file.
	*
	* @param BoxedCommand $command
	* @param string $boxedName
	* @param array $params Parameters include:
	* - src : source storage path
	* - latest : use the latest available data
	* @return StatusValue
	* @since 1.43
	*/
	abstract public function addShellboxInputFile( BoxedCommand $command, string $boxedName,
	array $params );

	/**
	* Check if a directory exists at a given storage path
	*
	* For backends using key/value stores, a directory is said to exist whenever
	* there exist any files with paths using the given directory path as a prefix
	* followed by a forward slash. For example, if there is a file called
	* "mwstore://backend/container/dir/path.svg" then directories are said to exist
	* at "mwstore://backend/container" and "mwstore://backend/container/dir". These
	* can be thought of as "virtual" directories.
	*
	* Backends that directly use a filesystem layer might enumerate empty directories.
	* The clean() method should always be used when files are deleted or moved if this
	* is a concern. This is a trade-off to avoid write amplication/contention on file
	* changes or read amplification when calling this method.
	*
	* Storage backends with eventual consistency might return stale data.
	*
	* @see FileBackend::EXISTENCE_ERROR
	* @see FileBackend::clean()
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* @return bool\|null Whether a directory exists or null (I/O error)
	* @since 1.20
	*/
	abstract public function directoryExists( array $params );

	/**
	* Get an iterator to list all directories under a storage directory
	*
	* If the directory is of the form "mwstore://backend/container",
	* then all directories in the container will be listed.
	* If the directory is of form "mwstore://backend/container/dir",
	* then all directories directly under that directory will be listed.
	* Results will be storage directories relative to the given directory.
	*
	* Storage backends with eventual consistency might return stale data.
	*
	* Failures during iteration can result in FileBackendError exceptions (since 1.22).
	*
	* @see FileBackend::LIST_ERROR
	* @see FileBackend::directoryExists()
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - topOnly : only return direct child dirs of the directory
	* @return \Traversable\|array\|null Directory list enumerator or null (initial I/O error)
	* @since 1.20
	*/
	abstract public function getDirectoryList( array $params );

	/**
	* Same as FileBackend::getDirectoryList() except only lists
	* directories that are immediately under the given directory.
	*
	* Storage backends with eventual consistency might return stale data.
	*
	* Failures during iteration can result in FileBackendError exceptions (since 1.22).
	*
	* @see FileBackend::LIST_ERROR
	* @see FileBackend::directoryExists()
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* @return \Traversable\|array\|null Directory list enumerator or null (initial I/O error)
	* @since 1.20
	*/
	final public function getTopDirectoryList( array $params ) {
	return $this->getDirectoryList( [ 'topOnly' => true ] + $params );
	}

	/**
	* Get an iterator to list all stored files under a storage directory
	*
	* If the directory is of the form "mwstore://backend/container", then all
	* files in the container will be listed. If the directory is of form
	* "mwstore://backend/container/dir", then all files under that directory will
	* be listed. Results will be storage paths relative to the given directory.
	*
	* Storage backends with eventual consistency might return stale data.
	*
	* Failures during iteration can result in FileBackendError exceptions (since 1.22).
	*
	* @see FileBackend::LIST_ERROR
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - topOnly : only return direct child files of the directory (since 1.20)
	* - adviseStat : set to true if stat requests will be made on the files (since 1.22)
	* - forWrite : true if the list will inform a write operations (since 1.41)
	* @return \Traversable\|array\|null File list enumerator or null (initial I/O error)
	*/
	abstract public function getFileList( array $params );

	/**
	* Same as FileBackend::getFileList() except only lists
	* files that are immediately under the given directory.
	*
	* Storage backends with eventual consistency might return stale data.
	*
	* Failures during iteration can result in FileBackendError exceptions (since 1.22).
	*
	* @see FileBackend::LIST_ERROR
	*
	* @param array $params Parameters include:
	* - dir : storage directory
	* - adviseStat : set to true if stat requests will be made on the files (since 1.22)
	* @return \Traversable\|array\|null File list enumerator or null on failure
	* @since 1.20
	*/
	final public function getTopFileList( array $params ) {
	return $this->getFileList( [ 'topOnly' => true ] + $params );
	}

	/**
	* Preload persistent file stat cache and property cache into in-process cache.
	* This should be used when stat calls will be made on a known list of a many files.
	*
	* @see FileBackend::getFileStat()
	*
	* @param array $paths Storage paths
	*/
	abstract public function preloadCache( array $paths );

	/**
	* Invalidate any in-process file stat and property cache.
	* If $paths is given, then only the cache for those files will be cleared.
	*
	* @see FileBackend::getFileStat()
	*
	* @param array\|null $paths Storage paths (optional)
	*/
	abstract public function clearCache( ?array $paths = null );

	/**
	* Preload file stat information (concurrently if possible) into in-process cache.
	*
	* This should be used when stat calls will be made on a known list of a many files.
	* This does not make use of the persistent file stat cache.
	*
	* @see FileBackend::getFileStat()
	*
	* @param array $params Parameters include:
	* - srcs : list of source storage paths
	* - latest : use the latest available data
	* @return bool Whether all requests proceeded without I/O errors (since 1.24)
	* @since 1.23
	*/
	abstract public function preloadFileStat( array $params );

	/**
	* Lock the files at the given storage paths in the backend.
	* This will either lock all the files or none (on failure).
	*
	* Callers should consider using getScopedFileLocks() instead.
	*
	* @param array $paths Storage paths
	* @param int $type LockManager::LOCK_* constant
	* @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
	* @return StatusValue
	*/
	final public function lockFiles( array $paths, $type, $timeout = 0 ) {
	$paths = array_map( [ __CLASS__, 'normalizeStoragePath' ], $paths );

	return $this->wrapStatus( $this->lockManager->lock( $paths, $type, $timeout ) );
	}

	/**
	* Unlock the files at the given storage paths in the backend.
	*
	* @param array $paths Storage paths
	* @param int $type LockManager::LOCK_* constant
	* @return StatusValue
	*/
	final public function unlockFiles( array $paths, $type ) {
	$paths = array_map( [ __CLASS__, 'normalizeStoragePath' ], $paths );

	return $this->wrapStatus( $this->lockManager->unlock( $paths, $type ) );
	}

	/**
	* Lock the files at the given storage paths in the backend.
	* This will either lock all the files or none (on failure).
	* On failure, the StatusValue object will be updated with errors.
	*
	* Once the return value goes out scope, the locks will be released and
	* the StatusValue updated. Unlock fatals will not change the StatusValue "OK" value.
	*
	* @see ScopedLock::factory()
	*
	* @param array $paths List of storage paths or map of lock types to path lists
	* @param int\|string $type LockManager::LOCK_* constant or "mixed"
	* @param StatusValue $status StatusValue to update on lock/unlock
	* @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
	* @return ScopedLock\|null RAII-style self-unlocking lock or null on failure
	*/
	final public function getScopedFileLocks(
	array $paths, $type, StatusValue $status, $timeout = 0
	) {
	if ( $type === 'mixed' ) {
	foreach ( $paths as &$typePaths ) {
	$typePaths = array_map( [ __CLASS__, 'normalizeStoragePath' ], $typePaths );
	}
	} else {
	$paths = array_map( [ __CLASS__, 'normalizeStoragePath' ], $paths );
	}

	return ScopedLock::factory( $this->lockManager, $paths, $type, $status, $timeout );
	}

	/**
	* Get an array of scoped locks needed for a batch of file operations.
	*
	* Normally, FileBackend::doOperations() handles locking, unless
	* the 'nonLocking' param is passed in. This function is useful if you
	* want the files to be locked for a broader scope than just when the
	* files are changing. For example, if you need to update DB metadata,
	* you may want to keep the files locked until finished.
	*
	* @see FileBackend::doOperations()
	*
	* @param array $ops List of file operations to FileBackend::doOperations()
	* @param StatusValue $status StatusValue to update on lock/unlock
	* @return ScopedLock\|null RAII-style self-unlocking lock or null on failure
	* @since 1.20
	*/
	abstract public function getScopedLocksForOps( array $ops, StatusValue $status );

	/**
	* Get the root storage path of this backend.
	* All container paths are "subdirectories" of this path.
	*
	* @return string Storage path
	* @since 1.20
	*/
	final public function getRootStoragePath() {
	return "mwstore://{$this->name}";
	}

	/**
	* Get the storage path for the given container for this backend
	*
	* @param string $container Container name
	* @return string Storage path
	* @since 1.21
	*/
	final public function getContainerStoragePath( $container ) {
	return $this->getRootStoragePath() . "/{$container}";
	}

	/**
	* Convert FSFile 'src' paths to string paths (with an 'srcRef' field set to the FSFile)
	*
	* The 'srcRef' field keeps any TempFSFile objects in scope for the backend to have it
	* around as long it needs (which may vary greatly depending on configuration)
	*
	* @param array $ops File operation batch for FileBaclend::doOperations()
	* @return array File operation batch
	*/
	protected function resolveFSFileObjects( array $ops ) {
	foreach ( $ops as &$op ) {
	$src = $op['src'] ?? null;
	if ( $src instanceof FSFile ) {
	$op['srcRef'] = $src;
	$op['src'] = $src->getPath();
	}
	}
	unset( $op );

	return $ops;
	}

	/**
	* Check if a given path is a "mwstore://" path.
	* This does not do any further validation or any existence checks.
	*
	* @param string\|null $path
	* @return bool
	*/
	final public static function isStoragePath( $path ) {
	return ( strpos( $path ?? '', 'mwstore://' ) === 0 );
	}

	/**
	* Split a storage path into a backend name, a container name,
	* and a relative file path. The relative path may be the empty string.
	* This does not do any path normalization or traversal checks.
	*
	* @param string $storagePath
	* @return array (backend, container, rel object) or (null, null, null)
	*/
	final public static function splitStoragePath( $storagePath ) {
	if ( self::isStoragePath( $storagePath ) ) {
	// Remove the "mwstore://" prefix and split the path
	$parts = explode( '/', substr( $storagePath, 10 ), 3 );
	if ( count( $parts ) >= 2 && $parts[0] != '' && $parts[1] != '' ) {
	if ( count( $parts ) == 3 ) {
	return $parts; // e.g. "backend/container/path"
	} else {
	return [ $parts[0], $parts[1], '' ]; // e.g. "backend/container"
	}
	}
	}

	return [ null, null, null ];
	}

	/**
	* Normalize a storage path by cleaning up directory separators.
	* Returns null if the path is not of the format of a valid storage path.
	*
	* @param string $storagePath
	* @return string\|null Normalized storage path or null on failure
	*/
	final public static function normalizeStoragePath( $storagePath ) {
	[ $backend, $container, $relPath ] = self::splitStoragePath( $storagePath );
	if ( $relPath !== null ) { // must be for this backend
	$relPath = self::normalizeContainerPath( $relPath );
	if ( $relPath !== null ) {
	return ( $relPath != '' )
	? "mwstore://{$backend}/{$container}/{$relPath}"
	: "mwstore://{$backend}/{$container}";
	}
	}

	return null;
	}

	/**
	* Get the parent storage directory of a storage path.
	* This returns a path like "mwstore://backend/container",
	* "mwstore://backend/container/...", or null if there is no parent.
	*
	* @param string $storagePath
	* @return string\|null Parent storage path or null on failure
	*/
	final public static function parentStoragePath( $storagePath ) {
	// XXX dirname() depends on platform and locale! If nothing enforces that the storage path
	// doesn't contain characters like '\', behavior can vary by platform. We should use
	// explode() instead.
	$storagePath = dirname( $storagePath );
	[ , , $rel ] = self::splitStoragePath( $storagePath );

	return ( $rel === null ) ? null : $storagePath;
	}

	/**
	* Get the final extension from a storage or FS path
	*
	* @param string $path
	* @param string $case One of (rawcase, uppercase, lowercase) (since 1.24)
	* @return string
	*/
	final public static function extensionFromPath( $path, $case = 'lowercase' ) {
	// This will treat a string starting with . as not having an extension, but store paths have
	// to start with 'mwstore://', so "garbage in, garbage out".
	$i = strrpos( $path ?? '', '.' );
	$ext = $i ? substr( $path, $i + 1 ) : '';

	if ( $case === 'lowercase' ) {
	$ext = strtolower( $ext );
	} elseif ( $case === 'uppercase' ) {
	$ext = strtoupper( $ext );
	}

	return $ext;
	}

	/**
	* Check if a relative path has no directory traversals
	*
	* @param string $path
	* @return bool
	* @since 1.20
	*/
	final public static function isPathTraversalFree( $path ) {
	return ( self::normalizeContainerPath( $path ) !== null );
	}

	/**
	* Build a Content-Disposition header value per RFC 6266.
	*
	* @param string $type One of (attachment, inline)
	* @param string $filename Suggested file name (should not contain slashes)
	* @return string
	* @since 1.20
	*/
	final public static function makeContentDisposition( $type, $filename = '' ) {
	$parts = [];

	$type = strtolower( $type );
	if ( !in_array( $type, [ 'inline', 'attachment' ] ) ) {
	throw new InvalidArgumentException( "Invalid Content-Disposition type '$type'." );
	}
	$parts[] = $type;

	if ( strlen( $filename ) ) {
	$parts[] = "filename*=UTF-8''" . rawurlencode( basename( $filename ) );
	}

	return implode( ';', $parts );
	}

	/**
	* Validate and normalize a relative storage path.
	* Null is returned if the path involves directory traversal.
	* Traversal is insecure for FS backends and broken for others.
	*
	* This uses the same traversal protection as Title::secureAndSplit().
	*
	* @param string $path Storage path relative to a container
	* @return string\|null Normalized container path or null on failure
	*/
	final protected static function normalizeContainerPath( $path ) {
	// Normalize directory separators
	$path = strtr( $path, '\\', '/' );
	// Collapse any consecutive directory separators
	$path = preg_replace( '![/]{2,}!', '/', $path );
	// Remove any leading directory separator
	$path = ltrim( $path, '/' );
	// Use the same traversal protection as Title::secureAndSplit()
	if ( strpos( $path, '.' ) !== false ) {
	if (
	$path === '.' \|\|
	$path === '..' \|\|
	strpos( $path, './' ) === 0 \|\|
	strpos( $path, '../' ) === 0 \|\|
	strpos( $path, '/./' ) !== false \|\|
	strpos( $path, '/../' ) !== false
	) {
	return null;
	}
	}

	return $path;
	}

	/**
	* Yields the result of the status wrapper callback on either:
	* - StatusValue::newGood() if this method is called without parameters
	* - StatusValue::newFatal() with all parameters to this method if passed in
	*
	* @param mixed ...$args
	* @return StatusValue
	*/
	final protected function newStatus( ...$args ) {
	if ( count( $args ) ) {
	$sv = StatusValue::newFatal( ...$args );
	} else {
	$sv = StatusValue::newGood();
	}

	return $this->wrapStatus( $sv );
	}

	/**
	* @param StatusValue $sv
	* @return StatusValue Modified status or StatusValue subclass
	*/
	final protected function wrapStatus( StatusValue $sv ) {
	return $this->statusWrapper ? call_user_func( $this->statusWrapper, $sv ) : $sv;
	}

	/**
	* @param string $section
	* @return ScopedCallback\|null
	*/
	protected function scopedProfileSection( $section ) {
	return $this->profiler ? ( $this->profiler )( $section ) : null;
	}

	/**
	* Default behavior of resetOutputBuffer().
	* @codeCoverageIgnore
	* @internal
	*/
	public static function resetOutputBufferTheDefaultWay() {
	// XXX According to documentation, ob_get_status() always returns a non-empty array and this
	// condition will always be true
	while ( ob_get_status() ) {
	if ( !ob_end_clean() ) {
	// Could not remove output buffer handler; abort now
	// to avoid getting in some kind of infinite loop.
	break;
	}
	}
	}

	/**
	* Return options for use with HTTPFileStreamer.
	*
	* @internal
	*/
	public function getStreamerOptions(): array {
	return $this->streamerOptions;
	}
	}
	/** @deprecated class alias since 1.43 */
	class_alias( FileBackend::class, 'FileBackend' );

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