<?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.
*/
/**
* 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
* @author Aaron Schulz
*/
/**
* @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 MediaWiki 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 wiki-specific container names by default.
* Global (qualified) backends are achieved by configuring the "wiki ID" to a constant.
* For legacy reasons, the FSFileBackend class allows manually setting the paths of
* containers to ones that do not respect the "wiki 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.
*
* @ingroup FileBackend
* @since 1.19
*/
abstract class FileBackend {
/** @var string Unique backend name */
protected $name;
/** @var string Unique wiki name */
protected $wikiId;
/** @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 LockManager */
protected $lockManager;
/** @var FileJournal */
protected $fileJournal;
/** Bitfield flags for supported features */
const ATTR_HEADERS = 1; // files can be tagged with standard HTTP headers
const ATTR_METADATA = 2; // files can be stored with metadata key/values
const ATTR_UNICODE_PATHS = 4; // files can have Unicode paths (not just ASCII)
/**
* Create a new backend instance from configuration.
* This should only be called from within FileBackendGroup.
*
* @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 (e.g. with journaling).
* Note that the name is *not* used in actual container names.
* - wikiId : 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.
* - fileJournal : FileJournal object to use for logging changes to files.
* If not provided, then change journaling will be disabled.
* - 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.
* @throws FileBackendException
*/
public function __construct( array $config ) {
$this->name = $config['name'];
$this->wikiId = $config['wikiId']; // e.g. "my_wiki-en_"
if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) {
throw new FileBackendException( "Backend name '{$this->name}' is invalid." );
} elseif ( !is_string( $this->wikiId ) ) {
throw new FileBackendException( "Backend wiki ID not provided for '{$this->name}'." );
}
$this->lockManager = isset( $config['lockManager'] )
? $config['lockManager']
: new NullLockManager( array() );
$this->fileJournal = isset( $config['fileJournal'] )
? $config['fileJournal']
: FileJournal::factory( array( 'class' => 'NullFileJournal' ), $this->name );
$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;
}
/**
* 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 wiki identifier used for this backend (possibly empty).
* Note that this might *not* be in the same format as wfWikiID().
*
* @return string
* @since 1.20
*/
final public function getWikiId() {
return $this->wikiId;
}
/**
* 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
*
* @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
*
* a) Create a new file in storage with the contents of a string
* @code
* array(
* '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
* array(
* 'op' => 'store',
* 'src' => <file system path>,
* 'dst' => <storage path>,
* 'overwrite' => <boolean>,
* 'overwriteSame' => <boolean>,
* 'headers' => <HTTP header name/value map> # since 1.21
* )
* @endcode
*
* c) Copy a file within storage
* @code
* array(
* '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
* array(
* '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
* array(
* 'op' => 'delete',
* 'src' => <storage path>,
* 'ignoreMissingSource' => <boolean>
* )
* @endcode
*
* f) Update metadata for a file within storage
* @code
* array(
* 'op' => 'describe',
* 'src' => <storage path>,
* 'headers' => <HTTP header name/value map>
* )
* @endcode
*
* g) Do nothing (no-op)
* @code
* array(
* '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.
* - nonJournaled : Don't log this operation batch in the file journal.
* This limits the ability of recovery scripts.
* - 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)
*
* @remarks 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 status will be "OK" unless:
* - a) unexpected operation errors occurred (network partitions, disk full...)
* - b) significant operation errors occurred and 'force' was not set
*
* @param array $ops List of operations to execute in order
* @param array $opts Batch operation options
* @return Status
*/
final public function doOperations( array $ops, array $opts = array() ) {
if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
if ( !count( $ops ) ) {
return Status::newGood(); // nothing to do
}
if ( empty( $opts['force'] ) ) { // sanity
unset( $opts['nonLocking'] );
}
foreach ( $ops as &$op ) {
if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
$op['headers']['Content-Disposition'] = $op['disposition'];
}
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doOperationsInternal( $ops, $opts );
}
/**
* @see FileBackend::doOperations()
* @param array $ops
* @param array $opts
*/
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 Status
*/
final public function doOperation( array $op, array $opts = array() ) {
return $this->doOperations( array( $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 Status
*/
final public function create( array $params, array $opts = array() ) {
return $this->doOperation( array( '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 Status
*/
final public function store( array $params, array $opts = array() ) {
return $this->doOperation( array( '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 Status
*/
final public function copy( array $params, array $opts = array() ) {
return $this->doOperation( array( '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 Status
*/
final public function move( array $params, array $opts = array() ) {
return $this->doOperation( array( '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 Status
*/
final public function delete( array $params, array $opts = array() ) {
return $this->doOperation( array( '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 Status
* @since 1.21
*/
final public function describe( array $params, array $opts = array() ) {
return $this->doOperation( array( 'op' => 'describe' ) + $params, $opts );
}
/**
* Perform a set of independent file operations on some files.
*
* This does no locking, nor journaling, 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
*
* a) Create a new file in storage with the contents of a string
* @code
* array(
* '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
* array(
* 'op' => 'store',
* 'src' => <file system path>,
* 'dst' => <storage path>,
* 'headers' => <HTTP header name/value map> # since 1.21
* )
* @endcode
*
* c) Copy a file within storage
* @code
* array(
* '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
* array(
* '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
* array(
* 'op' => 'delete',
* 'src' => <storage path>,
* 'ignoreMissingSource' => <boolean>
* )
* @endcode
*
* f) Update metadata for a file within storage
* @code
* array(
* 'op' => 'describe',
* 'src' => <storage path>,
* 'headers' => <HTTP header name/value map>
* )
* @endcode
*
* g) Do nothing (no-op)
* @code
* array(
* '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 status will be
* considered "OK" as long as no fatal errors occurred.
*
* @param array $ops Set of operations to execute
* @param array $opts Batch operation options
* @return Status
* @since 1.20
*/
final public function doQuickOperations( array $ops, array $opts = array() ) {
if ( empty( $opts['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
if ( !count( $ops ) ) {
return Status::newGood(); // nothing to do
}
foreach ( $ops as &$op ) {
$op['overwrite'] = true; // avoids RTTs in key/value stores
if ( isset( $op['disposition'] ) ) { // b/c (MW 1.20)
$op['headers']['Content-Disposition'] = $op['disposition'];
}
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doQuickOperationsInternal( $ops );
}
/**
* @see FileBackend::doQuickOperations()
* @param array $ops
* @since 1.20
*/
abstract protected function doQuickOperationsInternal( array $ops );
/**
* 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
* @return Status
* @since 1.20
*/
final public function doQuickOperation( array $op ) {
return $this->doQuickOperations( array( $op ) );
}
/**
* 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
* @return Status
* @since 1.20
*/
final public function quickCreate( array $params ) {
return $this->doQuickOperation( array( 'op' => 'create' ) + $params );
}
/**
* 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
* @return Status
* @since 1.20
*/
final public function quickStore( array $params ) {
return $this->doQuickOperation( array( 'op' => 'store' ) + $params );
}
/**
* 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
* @return Status
* @since 1.20
*/
final public function quickCopy( array $params ) {
return $this->doQuickOperation( array( 'op' => 'copy' ) + $params );
}
/**
* 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
* @return Status
* @since 1.20
*/
final public function quickMove( array $params ) {
return $this->doQuickOperation( array( 'op' => 'move' ) + $params );
}
/**
* 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
* @return Status
* @since 1.20
*/
final public function quickDelete( array $params ) {
return $this->doQuickOperation( array( 'op' => 'delete' ) + $params );
}
/**
* 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
* @return Status
* @since 1.21
*/
final public function quickDescribe( array $params ) {
return $this->doQuickOperation( array( 'op' => 'describe' ) + $params );
}
/**
* 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 Status
*/
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 Status
*/
final public function prepare( array $params ) {
if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doPrepare( $params );
}
/**
* @see FileBackend::prepare()
* @param array $params
*/
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 publically 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 Status
*/
final public function secure( array $params ) {
if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doSecure( $params );
}
/**
* @see FileBackend::secure()
* @param array $params
*/
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 publically 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 Status
* @since 1.20
*/
final public function publish( array $params ) {
if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doPublish( $params );
}
/**
* @see FileBackend::publish()
* @param array $params
*/
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 Status
*/
final public function clean( array $params ) {
if ( empty( $params['bypassReadOnly'] ) && $this->isReadOnly() ) {
return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly );
}
/** @noinspection PhpUnusedLocalVariableInspection */
$scope = $this->getScopedPHPBehaviorForOps(); // try to ignore client aborts
return $this->doClean( $params );
}
/**
* @see FileBackend::clean()
* @param array $params
*/
abstract protected function doClean( array $params );
/**
* Enter file operation scope.
* This just makes PHP ignore user aborts/disconnects until the return
* value leaves scope. This returns null and does nothing in CLI mode.
*
* @return ScopedCallback|null
*/
final protected function getScopedPHPBehaviorForOps() {
if ( PHP_SAPI != 'cli' ) { // http://bugs.php.net/bug.php?id=47540
$old = ignore_user_abort( true ); // avoid half-finished operations
return new ScopedCallback( function () use ( $old ) {
ignore_user_abort( $old );
} );
}
return null;
}
/**
* Check if a file exists at a storage path in the backend.
* This returns false if only a directory exists at the path.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return bool|null Returns null on failure
*/
abstract public function fileExists( array $params );
/**
* Get the last-modified timestamp of the file at a storage path.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return string|bool TS_MW timestamp or false on failure
*/
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.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return string|bool Returns false on failure
*/
final public function getFileContents( array $params ) {
$contents = $this->getFileContentsMulti(
array( 'srcs' => array( $params['src'] ) ) + $params );
return $contents[$params['src']];
}
/**
* Like getFileContents() except it takes an array of storage paths
* and returns a map of storage paths to strings (or null on failure).
* The map keys (paths) are in the same order as the provided list of paths.
*
* @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 array Map of (path name => string 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.
*
* @param array $params
* $params include:
* - src : source storage path
* - latest : use the latest available data
* @return array|bool Returns false on failure
* @since 1.23
*/
abstract public function getFileXAttributes( array $params );
/**
* Get the size (bytes) of a file at a storage path in the backend.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return int|bool Returns false on failure
*/
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.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return array|bool|null Returns null on failure
*/
abstract public function getFileStat( array $params );
/**
* Get a SHA-1 hash of the file at a storage path in the backend.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return string|bool Hash string or false on failure
*/
abstract public function getFileSha1Base36( array $params );
/**
* Get the properties 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 Returns FSFile::placeholderProps() on failure
*/
abstract public function getFileProps( array $params );
/**
* Stream 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 on success
* - latest : use the latest available data
* @return Status
*/
abstract public function streamFile( array $params );
/**
* Returns a file system file, identical to the file at a storage path.
* The file returned is either:
* - a) A local copy of the file at a storage path in the backend.
* The temporary copy will have the same extension as the source.
* - b) An original of the file at a storage path in the backend.
* Temporary files may be purged when the file object falls out of scope.
*
* Write operations should *never* be done on this file as some backends
* may do internal tracking or may be instances of FileBackendMultiWrite.
* In that later case, there are copies of the file that must stay in sync.
* Additionally, further calls to this function may return the same file.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return FSFile|null Returns null on failure
*/
final public function getLocalReference( array $params ) {
$fsFiles = $this->getLocalReferenceMulti(
array( 'srcs' => array( $params['src'] ) ) + $params );
return $fsFiles[$params['src']];
}
/**
* Like getLocalReference() except it takes an array of storage paths
* and returns a map of storage paths to FSFile objects (or null on failure).
* The map keys (paths) are in the same order as the provided list of paths.
*
* @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 null on failure)
* @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.
*
* @param array $params Parameters include:
* - src : source storage path
* - latest : use the latest available data
* @return TempFSFile|null Returns null on failure
*/
final public function getLocalCopy( array $params ) {
$tmpFiles = $this->getLocalCopyMulti(
array( 'srcs' => array( $params['src'] ) ) + $params );
return $tmpFiles[$params['src']];
}
/**
* Like getLocalCopy() except it takes an array of storage paths and
* returns a map of storage paths to TempFSFile objects (or null on failure).
* The map keys (paths) are in the same order as the provided list of paths.
*
* @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 null on failure)
* @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.
*
* @param array $params Parameters include:
* - src : source storage path
* - ttl : lifetime (seconds) if pre-authenticated; default is 1 day
* @return string|null
* @since 1.21
*/
abstract public function getFileHttpUrl( array $params );
/**
* Check if a directory exists at a given storage path.
* Backends using key/value stores will check if the path is a
* virtual directory, meaning there are files under the given directory.
*
* Storage backends with eventual consistency might return stale data.
*
* @param array $params Parameters include:
* - dir : storage directory
* @return bool|null Returns null on failure
* @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).
*
* @param array $params Parameters include:
* - dir : storage directory
* - topOnly : only return direct child dirs of the directory
* @return Traversable|array|null Returns null on failure
* @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).
*
* @param array $params Parameters include:
* - dir : storage directory
* @return Traversable|array|null Returns null on failure
* @since 1.20
*/
final public function getTopDirectoryList( array $params ) {
return $this->getDirectoryList( array( '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).
*
* @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)
* @return Traversable|array|null Returns null on failure
*/
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).
*
* @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 Returns null on failure
* @since 1.20
*/
final public function getTopFileList( array $params ) {
return $this->getFileList( array( '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 $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 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 Status
*/
final public function lockFiles( array $paths, $type, $timeout = 0 ) {
$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
return $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 Status
*/
final public function unlockFiles( array $paths, $type ) {
$paths = array_map( 'FileBackend::normalizeStoragePath', $paths );
return $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 status object will be updated with errors.
*
* Once the return value goes out scope, the locks will be released and
* the status updated. Unlock fatals will not change the status "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 Status $status Status to update on lock/unlock
* @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.24)
* @return ScopedLock|null Returns null on failure
*/
final public function getScopedFileLocks( array $paths, $type, Status $status, $timeout = 0 ) {
if ( $type === 'mixed' ) {
foreach ( $paths as &$typePaths ) {
$typePaths = array_map( 'FileBackend::normalizeStoragePath', $typePaths );
}
} else {
$paths = array_map( 'FileBackend::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 Status $status Status to update on lock/unlock
* @return ScopedLock|null
* @since 1.20
*/
abstract public function getScopedLocksForOps( array $ops, Status $status );
/**
* Get the root storage path of this backend.
* All container paths are "subdirectories" of this path.
*
* @return string Storage path
* @since 1.20
*/
final public function getRootStoragePath() {
return "mwstore://{$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}";
}
/**
* Get the file journal object for this backend
*
* @return FileJournal
*/
final public function getJournal() {
return $this->fileJournal;
}
/**
* Check if a given path is a "mwstore://" path.
* This does not do any further validation or any existence checks.
*
* @param string $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 array( $parts[0], $parts[1], '' ); // e.g. "backend/container"
}
}
}
return array( 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
*/
final public static function normalizeStoragePath( $storagePath ) {
list( $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
*/
final public static function parentStoragePath( $storagePath ) {
$storagePath = dirname( $storagePath );
list( , , $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' ) {
$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)
* @throws FileBackendError
* @return string
* @since 1.20
*/
final public static function makeContentDisposition( $type, $filename = '' ) {
$parts = array();
$type = strtolower( $type );
if ( !in_array( $type, array( 'inline', 'attachment' ) ) ) {
throw new FileBackendError( "Invalid Content-Disposition type '$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
*/
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;
}
}
/**
* Generic file backend exception for checked and unexpected (e.g. config) exceptions
*
* @ingroup FileBackend
* @since 1.23
*/
class FileBackendException extends Exception {
}
/**
* File backend exception for checked exceptions (e.g. I/O errors)
*
* @ingroup FileBackend
* @since 1.22
*/
class FileBackendError extends FileBackendException {
}