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Diffstat (limited to 'includes/filerepo/backend/FileBackend.php')
| -rw-r--r-- | includes/filerepo/backend/FileBackend.php | 1739 |
1 files changed, 1739 insertions, 0 deletions
diff --git a/includes/filerepo/backend/FileBackend.php b/includes/filerepo/backend/FileBackend.php new file mode 100644 index 00000000..9433bcb4 --- /dev/null +++ b/includes/filerepo/backend/FileBackend.php @@ -0,0 +1,1739 @@ +<?php +/** + * @defgroup FileBackend File backend + * @ingroup FileRepo + * + * This module regroup classes meant for MediaWiki to interacts with + */ + +/** + * @file + * @ingroup FileBackend + * @author Aaron Schulz + */ + +/** + * 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 paths use UNIX file system (FS) notation, though any particular backend may + * not actually be using a local filesystem. Therefore, the paths are only virtual. + * + * Backend contents are stored under wiki-specific container names by default. + * For legacy reasons, this has no effect for the FS backend class, and per-wiki + * segregation must be done by setting the container paths appropriately. + * + * 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. + * + * Methods 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 { + protected $name; // string; unique backend name + protected $wikiId; // string; unique wiki name + protected $readOnly; // string; read-only explanation message + /** @var LockManager */ + protected $lockManager; + + /** + * Create a new backend instance from configuration. + * This should only be called from within FileBackendGroup. + * + * $config includes: + * 'name' : The unique name of this backend. + * This should consist of alphanumberic, '-', and '_' characters. + * This name should not be changed after use. + * 'wikiId' : Prefix to container names that is unique to this wiki. + * This should consist of alphanumberic, '-', and '_' characters. + * 'lockManager' : Registered name of a file lock manager to use. + * 'readOnly' : Write operations are disallowed if this is a non-empty string. + * It should be an explanation for the backend being read-only. + * + * @param $config Array + */ + public function __construct( array $config ) { + $this->name = $config['name']; + if ( !preg_match( '!^[a-zA-Z0-9-_]{1,255}$!', $this->name ) ) { + throw new MWException( "Backend name `{$this->name}` is invalid." ); + } + $this->wikiId = isset( $config['wikiId'] ) + ? $config['wikiId'] + : wfWikiID(); // e.g. "my_wiki-en_" + $this->lockManager = ( $config['lockManager'] instanceof LockManager ) + ? $config['lockManager'] + : LockManagerGroup::singleton()->get( $config['lockManager'] ); + $this->readOnly = isset( $config['readOnly'] ) + ? (string)$config['readOnly'] + : ''; + } + + /** + * 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; + } + + /** + * 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|false Returns falls if the backend is not read-only + */ + final public function getReadOnlyReason() { + return ( $this->readOnly != '' ) ? $this->readOnly : false; + } + + /** + * 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: + * a) Create a new file in storage with the contents of a string + * array( + * 'op' => 'create', + * 'dst' => <storage path>, + * 'content' => <string of new file contents>, + * 'overwrite' => <boolean>, + * 'overwriteSame' => <boolean> + * ) + * b) Copy a file system file into storage + * array( + * 'op' => 'store', + * 'src' => <file system path>, + * 'dst' => <storage path>, + * 'overwrite' => <boolean>, + * 'overwriteSame' => <boolean> + * ) + * c) Copy a file within storage + * array( + * 'op' => 'copy', + * 'src' => <storage path>, + * 'dst' => <storage path>, + * 'overwrite' => <boolean>, + * 'overwriteSame' => <boolean> + * ) + * d) Move a file within storage + * array( + * 'op' => 'move', + * 'src' => <storage path>, + * 'dst' => <storage path>, + * 'overwrite' => <boolean>, + * 'overwriteSame' => <boolean> + * ) + * e) Delete a file within storage + * array( + * 'op' => 'delete', + * 'src' => <storage path>, + * 'ignoreMissingSource' => <boolean> + * ) + * f) Do nothing (no-op) + * array( + * 'op' => 'null', + * ) + * + * 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' : An error will not be given if a file already + * exists at the destination that has the same + * contents as the new contents to be written there. + * + * $opts is an associative of boolean flags, including: + * 'force' : Errors that would normally cause a rollback do not. + * The remaining operations are still attempted if any fail. + * '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. + * 'allowStale' : Don't require the latest available data. + * This can increase performance for non-critical writes. + * This has no effect unless the 'force' flag is set. + * + * 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. + * + * Return value: + * This returns a Status, which contains all warnings and fatals that occured + * 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 occured and 'force' was not set + * + * @param $ops Array List of operations to execute in order + * @param $opts Array Batch operation options + * @return Status + */ + final public function doOperations( array $ops, array $opts = array() ) { + if ( $this->isReadOnly() ) { + return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly ); + } + if ( empty( $opts['force'] ) ) { // sanity + unset( $opts['nonLocking'] ); + unset( $opts['allowStale'] ); + } + return $this->doOperationsInternal( $ops, $opts ); + } + + /** + * @see FileBackend::doOperations() + */ + 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 $op Array Operation + * @param $opts Array 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 $params Array Operation parameters + * @param $opts Array Operation options + * @return Status + */ + final public function create( array $params, array $opts = array() ) { + $params['op'] = 'create'; + return $this->doOperation( $params, $opts ); + } + + /** + * Performs a single store operation. + * This sets $params['op'] to 'store' and passes it to doOperation(). + * + * @see FileBackend::doOperation() + * + * @param $params Array Operation parameters + * @param $opts Array Operation options + * @return Status + */ + final public function store( array $params, array $opts = array() ) { + $params['op'] = 'store'; + return $this->doOperation( $params, $opts ); + } + + /** + * Performs a single copy operation. + * This sets $params['op'] to 'copy' and passes it to doOperation(). + * + * @see FileBackend::doOperation() + * + * @param $params Array Operation parameters + * @param $opts Array Operation options + * @return Status + */ + final public function copy( array $params, array $opts = array() ) { + $params['op'] = 'copy'; + return $this->doOperation( $params, $opts ); + } + + /** + * Performs a single move operation. + * This sets $params['op'] to 'move' and passes it to doOperation(). + * + * @see FileBackend::doOperation() + * + * @param $params Array Operation parameters + * @param $opts Array Operation options + * @return Status + */ + final public function move( array $params, array $opts = array() ) { + $params['op'] = 'move'; + return $this->doOperation( $params, $opts ); + } + + /** + * Performs a single delete operation. + * This sets $params['op'] to 'delete' and passes it to doOperation(). + * + * @see FileBackend::doOperation() + * + * @param $params Array Operation parameters + * @param $opts Array Operation options + * @return Status + */ + final public function delete( array $params, array $opts = array() ) { + $params['op'] = 'delete'; + return $this->doOperation( $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. + * $params include: + * srcs : ordered source storage paths (e.g. chunk1, chunk2, ...) + * dst : file system path to 0-byte temp file + * + * @param $params Array Operation parameters + * @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. + * + * $params include: + * dir : storage directory + * + * @param $params Array + * @return Status + */ + final public function prepare( array $params ) { + if ( $this->isReadOnly() ) { + return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly ); + } + return $this->doPrepare( $params ); + } + + /** + * @see FileBackend::prepare() + */ + 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 restrict container + * access to the auth user that represents end-users in web request. + * This is not guaranteed to actually do anything. + * + * $params include: + * dir : storage directory + * noAccess : try to deny file access + * noListing : try to deny file listing + * + * @param $params Array + * @return Status + */ + final public function secure( array $params ) { + if ( $this->isReadOnly() ) { + return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly ); + } + $status = $this->doPrepare( $params ); // dir must exist to restrict it + if ( $status->isOK() ) { + $status->merge( $this->doSecure( $params ) ); + } + return $status; + } + + /** + * @see FileBackend::secure() + */ + abstract protected function doSecure( 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 should be deleted. + * + * $params include: + * dir : storage directory + * + * @param $params Array + * @return Status + */ + final public function clean( array $params ) { + if ( $this->isReadOnly() ) { + return Status::newFatal( 'backend-fail-readonly', $this->name, $this->readOnly ); + } + return $this->doClean( $params ); + } + + /** + * @see FileBackend::clean() + */ + 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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return string|false 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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return string|false Returns false on failure + */ + abstract public function getFileContents( array $params ); + + /** + * Get the size (bytes) of a file at a storage path in the backend. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return integer|false 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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return Array|false|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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return string|false 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. + * Returns FSFile::placeholderProps() on failure. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return Array + */ + abstract public function getFileProps( array $params ); + + /** + * Stream the file at a storage path in the backend. + * If the file does not exists, a 404 error will be given. + * Appropriate HTTP headers (Status, Content-Type, Content-Length) + * must be sent if streaming began, while none should be sent otherwise. + * Implementations should flush the output buffer before sending data. + * + * $params include: + * src : source storage path + * headers : additional HTTP headers to send on success + * latest : use the latest available data + * + * @param $params Array + * @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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return FSFile|null Returns null on failure + */ + abstract public function getLocalReference( 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. + * + * $params include: + * src : source storage path + * latest : use the latest available data + * + * @param $params Array + * @return TempFSFile|null Returns null on failure + */ + abstract public function getLocalCopy( array $params ); + + /** + * Get an iterator to list out all stored files under a storage directory. + * If the directory is of the form "mwstore://backend/container", + * then all files in the container should be listed. + * If the directory is of form "mwstore://backend/container/dir", + * then all files under that container directory should be listed. + * Results should be storage paths relative to the given directory. + * + * Storage backends with eventual consistency might return stale data. + * + * $params include: + * dir : storage path directory + * + * @return Traversable|Array|null Returns null on failure + */ + abstract public function getFileList( array $params ); + + /** + * Invalidate any in-process file existence and property cache. + * If $paths is given, then only the cache for those files will be cleared. + * + * @param $paths Array Storage paths (optional) + * @return void + */ + public function clearCache( array $paths = null ) {} + + /** + * 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 $paths Array Storage paths + * @param $type integer LockManager::LOCK_* constant + * @return Status + */ + final public function lockFiles( array $paths, $type ) { + return $this->lockManager->lock( $paths, $type ); + } + + /** + * Unlock the files at the given storage paths in the backend. + * + * @param $paths Array Storage paths + * @param $type integer LockManager::LOCK_* constant + * @return Status + */ + final public function unlockFiles( array $paths, $type ) { + 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. + * + * @param $paths Array Storage paths + * @param $type integer LockManager::LOCK_* constant + * @param $status Status Status to update on lock/unlock + * @return ScopedLock|null Returns null on failure + */ + final public function getScopedFileLocks( array $paths, $type, Status $status ) { + return ScopedLock::factory( $this->lockManager, $paths, $type, $status ); + } + + /** + * Check if a given path is a "mwstore://" path. + * This does not do any further validation or any existence checks. + * + * @param $path string + * @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 $storagePath string + * @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 $storagePath string + * @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; + } + + /** + * 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. + * + * @param $path string 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; + } + + /** + * 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 $storagePath string + * @return string|null + */ + final public static function parentStoragePath( $storagePath ) { + $storagePath = dirname( $storagePath ); + list( $b, $cont, $rel ) = self::splitStoragePath( $storagePath ); + return ( $rel === null ) ? null : $storagePath; + } + + /** + * Get the final extension from a storage or FS path + * + * @param $path string + * @return string + */ + final public static function extensionFromPath( $path ) { + $i = strrpos( $path, '.' ); + return strtolower( $i ? substr( $path, $i + 1 ) : '' ); + } +} + +/** + * @brief Base class for all backends associated with a particular storage medium. + * + * This class defines the methods as abstract that subclasses must implement. + * Outside callers should *not* use functions with "Internal" in the name. + * + * The FileBackend operations are implemented using basic functions + * such as storeInternal(), copyInternal(), deleteInternal() and the like. + * This class is also responsible for path resolution and sanitization. + * + * @ingroup FileBackend + * @since 1.19 + */ +abstract class FileBackendStore extends FileBackend { + /** @var Array Map of paths to small (RAM/disk) cache items */ + protected $cache = array(); // (storage path => key => value) + protected $maxCacheSize = 100; // integer; max paths with entries + /** @var Array Map of paths to large (RAM/disk) cache items */ + protected $expensiveCache = array(); // (storage path => key => value) + protected $maxExpensiveCacheSize = 10; // integer; max paths with entries + + /** @var Array Map of container names to sharding settings */ + protected $shardViaHashLevels = array(); // (container name => config array) + + protected $maxFileSize = 1000000000; // integer bytes (1GB) + + /** + * Get the maximum allowable file size given backend + * medium restrictions and basic performance constraints. + * Do not call this function from places outside FileBackend and FileOp. + * + * @return integer Bytes + */ + final public function maxFileSizeInternal() { + return $this->maxFileSize; + } + + /** + * Check if a file can be created at a given storage path. + * FS backends should check if the parent directory exists and the file is writable. + * Backends using key/value stores should check if the container exists. + * + * @param $storagePath string + * @return bool + */ + abstract public function isPathUsableInternal( $storagePath ); + + /** + * Create a file in the backend with the given contents. + * Do not call this function from places outside FileBackend and FileOp. + * + * $params include: + * content : the raw file contents + * dst : destination storage path + * overwrite : overwrite any file that exists at the destination + * + * @param $params Array + * @return Status + */ + final public function createInternal( array $params ) { + wfProfileIn( __METHOD__ ); + if ( strlen( $params['content'] ) > $this->maxFileSizeInternal() ) { + $status = Status::newFatal( 'backend-fail-create', $params['dst'] ); + } else { + $status = $this->doCreateInternal( $params ); + $this->clearCache( array( $params['dst'] ) ); + } + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::createInternal() + */ + abstract protected function doCreateInternal( array $params ); + + /** + * Store a file into the backend from a file on disk. + * Do not call this function from places outside FileBackend and FileOp. + * + * $params include: + * src : source path on disk + * dst : destination storage path + * overwrite : overwrite any file that exists at the destination + * + * @param $params Array + * @return Status + */ + final public function storeInternal( array $params ) { + wfProfileIn( __METHOD__ ); + if ( filesize( $params['src'] ) > $this->maxFileSizeInternal() ) { + $status = Status::newFatal( 'backend-fail-store', $params['dst'] ); + } else { + $status = $this->doStoreInternal( $params ); + $this->clearCache( array( $params['dst'] ) ); + } + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::storeInternal() + */ + abstract protected function doStoreInternal( array $params ); + + /** + * Copy a file from one storage path to another in the backend. + * Do not call this function from places outside FileBackend and FileOp. + * + * $params include: + * src : source storage path + * dst : destination storage path + * overwrite : overwrite any file that exists at the destination + * + * @param $params Array + * @return Status + */ + final public function copyInternal( array $params ) { + wfProfileIn( __METHOD__ ); + $status = $this->doCopyInternal( $params ); + $this->clearCache( array( $params['dst'] ) ); + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::copyInternal() + */ + abstract protected function doCopyInternal( array $params ); + + /** + * Delete a file at the storage path. + * Do not call this function from places outside FileBackend and FileOp. + * + * $params include: + * src : source storage path + * ignoreMissingSource : do nothing if the source file does not exist + * + * @param $params Array + * @return Status + */ + final public function deleteInternal( array $params ) { + wfProfileIn( __METHOD__ ); + $status = $this->doDeleteInternal( $params ); + $this->clearCache( array( $params['src'] ) ); + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::deleteInternal() + */ + abstract protected function doDeleteInternal( array $params ); + + /** + * Move a file from one storage path to another in the backend. + * Do not call this function from places outside FileBackend and FileOp. + * + * $params include: + * src : source storage path + * dst : destination storage path + * overwrite : overwrite any file that exists at the destination + * + * @param $params Array + * @return Status + */ + final public function moveInternal( array $params ) { + wfProfileIn( __METHOD__ ); + $status = $this->doMoveInternal( $params ); + $this->clearCache( array( $params['src'], $params['dst'] ) ); + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::moveInternal() + */ + protected function doMoveInternal( array $params ) { + // Copy source to dest + $status = $this->copyInternal( $params ); + if ( $status->isOK() ) { + // Delete source (only fails due to races or medium going down) + $status->merge( $this->deleteInternal( array( 'src' => $params['src'] ) ) ); + $status->setResult( true, $status->value ); // ignore delete() errors + } + return $status; + } + + /** + * @see FileBackend::concatenate() + */ + final public function concatenate( array $params ) { + wfProfileIn( __METHOD__ ); + $status = Status::newGood(); + + // Try to lock the source files for the scope of this function + $scopeLockS = $this->getScopedFileLocks( $params['srcs'], LockManager::LOCK_UW, $status ); + if ( $status->isOK() ) { + // Actually do the concatenation + $status->merge( $this->doConcatenate( $params ) ); + } + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::concatenate() + */ + protected function doConcatenate( array $params ) { + $status = Status::newGood(); + $tmpPath = $params['dst']; // convenience + + // Check that the specified temp file is valid... + wfSuppressWarnings(); + $ok = ( is_file( $tmpPath ) && !filesize( $tmpPath ) ); + wfRestoreWarnings(); + if ( !$ok ) { // not present or not empty + $status->fatal( 'backend-fail-opentemp', $tmpPath ); + return $status; + } + + // Build up the temp file using the source chunks (in order)... + $tmpHandle = fopen( $tmpPath, 'ab' ); + if ( $tmpHandle === false ) { + $status->fatal( 'backend-fail-opentemp', $tmpPath ); + return $status; + } + foreach ( $params['srcs'] as $virtualSource ) { + // Get a local FS version of the chunk + $tmpFile = $this->getLocalReference( array( 'src' => $virtualSource ) ); + if ( !$tmpFile ) { + $status->fatal( 'backend-fail-read', $virtualSource ); + return $status; + } + // Get a handle to the local FS version + $sourceHandle = fopen( $tmpFile->getPath(), 'r' ); + if ( $sourceHandle === false ) { + fclose( $tmpHandle ); + $status->fatal( 'backend-fail-read', $virtualSource ); + return $status; + } + // Append chunk to file (pass chunk size to avoid magic quotes) + if ( !stream_copy_to_stream( $sourceHandle, $tmpHandle ) ) { + fclose( $sourceHandle ); + fclose( $tmpHandle ); + $status->fatal( 'backend-fail-writetemp', $tmpPath ); + return $status; + } + fclose( $sourceHandle ); + } + if ( !fclose( $tmpHandle ) ) { + $status->fatal( 'backend-fail-closetemp', $tmpPath ); + return $status; + } + + clearstatcache(); // temp file changed + + return $status; + } + + /** + * @see FileBackend::doPrepare() + */ + final protected function doPrepare( array $params ) { + wfProfileIn( __METHOD__ ); + + $status = Status::newGood(); + list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] ); + if ( $dir === null ) { + $status->fatal( 'backend-fail-invalidpath', $params['dir'] ); + wfProfileOut( __METHOD__ ); + return $status; // invalid storage path + } + + if ( $shard !== null ) { // confined to a single container/shard + $status->merge( $this->doPrepareInternal( $fullCont, $dir, $params ) ); + } else { // directory is on several shards + wfDebug( __METHOD__ . ": iterating over all container shards.\n" ); + list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] ); + foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) { + $status->merge( $this->doPrepareInternal( "{$fullCont}{$suffix}", $dir, $params ) ); + } + } + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::doPrepare() + */ + protected function doPrepareInternal( $container, $dir, array $params ) { + return Status::newGood(); + } + + /** + * @see FileBackend::doSecure() + */ + final protected function doSecure( array $params ) { + wfProfileIn( __METHOD__ ); + $status = Status::newGood(); + + list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] ); + if ( $dir === null ) { + $status->fatal( 'backend-fail-invalidpath', $params['dir'] ); + wfProfileOut( __METHOD__ ); + return $status; // invalid storage path + } + + if ( $shard !== null ) { // confined to a single container/shard + $status->merge( $this->doSecureInternal( $fullCont, $dir, $params ) ); + } else { // directory is on several shards + wfDebug( __METHOD__ . ": iterating over all container shards.\n" ); + list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] ); + foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) { + $status->merge( $this->doSecureInternal( "{$fullCont}{$suffix}", $dir, $params ) ); + } + } + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::doSecure() + */ + protected function doSecureInternal( $container, $dir, array $params ) { + return Status::newGood(); + } + + /** + * @see FileBackend::doClean() + */ + final protected function doClean( array $params ) { + wfProfileIn( __METHOD__ ); + $status = Status::newGood(); + + list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] ); + if ( $dir === null ) { + $status->fatal( 'backend-fail-invalidpath', $params['dir'] ); + wfProfileOut( __METHOD__ ); + return $status; // invalid storage path + } + + // Attempt to lock this directory... + $filesLockEx = array( $params['dir'] ); + $scopedLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status ); + if ( !$status->isOK() ) { + wfProfileOut( __METHOD__ ); + return $status; // abort + } + + if ( $shard !== null ) { // confined to a single container/shard + $status->merge( $this->doCleanInternal( $fullCont, $dir, $params ) ); + } else { // directory is on several shards + wfDebug( __METHOD__ . ": iterating over all container shards.\n" ); + list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] ); + foreach ( $this->getContainerSuffixes( $shortCont ) as $suffix ) { + $status->merge( $this->doCleanInternal( "{$fullCont}{$suffix}", $dir, $params ) ); + } + } + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::doClean() + */ + protected function doCleanInternal( $container, $dir, array $params ) { + return Status::newGood(); + } + + /** + * @see FileBackend::fileExists() + */ + final public function fileExists( array $params ) { + wfProfileIn( __METHOD__ ); + $stat = $this->getFileStat( $params ); + wfProfileOut( __METHOD__ ); + return ( $stat === null ) ? null : (bool)$stat; // null => failure + } + + /** + * @see FileBackend::getFileTimestamp() + */ + final public function getFileTimestamp( array $params ) { + wfProfileIn( __METHOD__ ); + $stat = $this->getFileStat( $params ); + wfProfileOut( __METHOD__ ); + return $stat ? $stat['mtime'] : false; + } + + /** + * @see FileBackend::getFileSize() + */ + final public function getFileSize( array $params ) { + wfProfileIn( __METHOD__ ); + $stat = $this->getFileStat( $params ); + wfProfileOut( __METHOD__ ); + return $stat ? $stat['size'] : false; + } + + /** + * @see FileBackend::getFileStat() + */ + final public function getFileStat( array $params ) { + wfProfileIn( __METHOD__ ); + $path = self::normalizeStoragePath( $params['src'] ); + if ( $path === null ) { + return false; // invalid storage path + } + $latest = !empty( $params['latest'] ); + if ( isset( $this->cache[$path]['stat'] ) ) { + // If we want the latest data, check that this cached + // value was in fact fetched with the latest available data. + if ( !$latest || $this->cache[$path]['stat']['latest'] ) { + wfProfileOut( __METHOD__ ); + return $this->cache[$path]['stat']; + } + } + $stat = $this->doGetFileStat( $params ); + if ( is_array( $stat ) ) { // don't cache negatives + $this->trimCache(); // limit memory + $this->cache[$path]['stat'] = $stat; + $this->cache[$path]['stat']['latest'] = $latest; + } + wfProfileOut( __METHOD__ ); + return $stat; + } + + /** + * @see FileBackendStore::getFileStat() + */ + abstract protected function doGetFileStat( array $params ); + + /** + * @see FileBackend::getFileContents() + */ + public function getFileContents( array $params ) { + wfProfileIn( __METHOD__ ); + $tmpFile = $this->getLocalReference( $params ); + if ( !$tmpFile ) { + wfProfileOut( __METHOD__ ); + return false; + } + wfSuppressWarnings(); + $data = file_get_contents( $tmpFile->getPath() ); + wfRestoreWarnings(); + wfProfileOut( __METHOD__ ); + return $data; + } + + /** + * @see FileBackend::getFileSha1Base36() + */ + final public function getFileSha1Base36( array $params ) { + wfProfileIn( __METHOD__ ); + $path = $params['src']; + if ( isset( $this->cache[$path]['sha1'] ) ) { + wfProfileOut( __METHOD__ ); + return $this->cache[$path]['sha1']; + } + $hash = $this->doGetFileSha1Base36( $params ); + if ( $hash ) { // don't cache negatives + $this->trimCache(); // limit memory + $this->cache[$path]['sha1'] = $hash; + } + wfProfileOut( __METHOD__ ); + return $hash; + } + + /** + * @see FileBackendStore::getFileSha1Base36() + */ + protected function doGetFileSha1Base36( array $params ) { + $fsFile = $this->getLocalReference( $params ); + if ( !$fsFile ) { + return false; + } else { + return $fsFile->getSha1Base36(); + } + } + + /** + * @see FileBackend::getFileProps() + */ + final public function getFileProps( array $params ) { + wfProfileIn( __METHOD__ ); + $fsFile = $this->getLocalReference( $params ); + $props = $fsFile ? $fsFile->getProps() : FSFile::placeholderProps(); + wfProfileOut( __METHOD__ ); + return $props; + } + + /** + * @see FileBackend::getLocalReference() + */ + public function getLocalReference( array $params ) { + wfProfileIn( __METHOD__ ); + $path = $params['src']; + if ( isset( $this->expensiveCache[$path]['localRef'] ) ) { + wfProfileOut( __METHOD__ ); + return $this->expensiveCache[$path]['localRef']; + } + $tmpFile = $this->getLocalCopy( $params ); + if ( $tmpFile ) { // don't cache negatives + $this->trimExpensiveCache(); // limit memory + $this->expensiveCache[$path]['localRef'] = $tmpFile; + } + wfProfileOut( __METHOD__ ); + return $tmpFile; + } + + /** + * @see FileBackend::streamFile() + */ + final public function streamFile( array $params ) { + wfProfileIn( __METHOD__ ); + $status = Status::newGood(); + + $info = $this->getFileStat( $params ); + if ( !$info ) { // let StreamFile handle the 404 + $status->fatal( 'backend-fail-notexists', $params['src'] ); + } + + // Set output buffer and HTTP headers for stream + $extraHeaders = isset( $params['headers'] ) ? $params['headers'] : array(); + $res = StreamFile::prepareForStream( $params['src'], $info, $extraHeaders ); + if ( $res == StreamFile::NOT_MODIFIED ) { + // do nothing; client cache is up to date + } elseif ( $res == StreamFile::READY_STREAM ) { + $status = $this->doStreamFile( $params ); + } else { + $status->fatal( 'backend-fail-stream', $params['src'] ); + } + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackendStore::streamFile() + */ + protected function doStreamFile( array $params ) { + $status = Status::newGood(); + + $fsFile = $this->getLocalReference( $params ); + if ( !$fsFile ) { + $status->fatal( 'backend-fail-stream', $params['src'] ); + } elseif ( !readfile( $fsFile->getPath() ) ) { + $status->fatal( 'backend-fail-stream', $params['src'] ); + } + + return $status; + } + + /** + * @copydoc FileBackend::getFileList() + */ + final public function getFileList( array $params ) { + list( $fullCont, $dir, $shard ) = $this->resolveStoragePath( $params['dir'] ); + if ( $dir === null ) { // invalid storage path + return null; + } + if ( $shard !== null ) { + // File listing is confined to a single container/shard + return $this->getFileListInternal( $fullCont, $dir, $params ); + } else { + wfDebug( __METHOD__ . ": iterating over all container shards.\n" ); + // File listing spans multiple containers/shards + list( $b, $shortCont, $r ) = self::splitStoragePath( $params['dir'] ); + return new FileBackendStoreShardListIterator( $this, + $fullCont, $dir, $this->getContainerSuffixes( $shortCont ), $params ); + } + } + + /** + * Do not call this function from places outside FileBackend + * + * @see FileBackendStore::getFileList() + * + * @param $container string Resolved container name + * @param $dir string Resolved path relative to container + * @param $params Array + * @return Traversable|Array|null + */ + abstract public function getFileListInternal( $container, $dir, array $params ); + + /** + * Get the list of supported operations and their corresponding FileOp classes. + * + * @return Array + */ + protected function supportedOperations() { + return array( + 'store' => 'StoreFileOp', + 'copy' => 'CopyFileOp', + 'move' => 'MoveFileOp', + 'delete' => 'DeleteFileOp', + 'create' => 'CreateFileOp', + 'null' => 'NullFileOp' + ); + } + + /** + * Return a list of FileOp objects from a list of operations. + * Do not call this function from places outside FileBackend. + * + * The result must have the same number of items as the input. + * An exception is thrown if an unsupported operation is requested. + * + * @param $ops Array Same format as doOperations() + * @return Array List of FileOp objects + * @throws MWException + */ + final public function getOperations( array $ops ) { + $supportedOps = $this->supportedOperations(); + + $performOps = array(); // array of FileOp objects + // Build up ordered array of FileOps... + foreach ( $ops as $operation ) { + $opName = $operation['op']; + if ( isset( $supportedOps[$opName] ) ) { + $class = $supportedOps[$opName]; + // Get params for this operation + $params = $operation; + // Append the FileOp class + $performOps[] = new $class( $this, $params ); + } else { + throw new MWException( "Operation `$opName` is not supported." ); + } + } + + return $performOps; + } + + /** + * @see FileBackend::doOperationsInternal() + */ + protected function doOperationsInternal( array $ops, array $opts ) { + wfProfileIn( __METHOD__ ); + $status = Status::newGood(); + + // Build up a list of FileOps... + $performOps = $this->getOperations( $ops ); + + // Acquire any locks as needed... + if ( empty( $opts['nonLocking'] ) ) { + // Build up a list of files to lock... + $filesLockEx = $filesLockSh = array(); + foreach ( $performOps as $fileOp ) { + $filesLockSh = array_merge( $filesLockSh, $fileOp->storagePathsRead() ); + $filesLockEx = array_merge( $filesLockEx, $fileOp->storagePathsChanged() ); + } + // Optimization: if doing an EX lock anyway, don't also set an SH one + $filesLockSh = array_diff( $filesLockSh, $filesLockEx ); + // Get a shared lock on the parent directory of each path changed + $filesLockSh = array_merge( $filesLockSh, array_map( 'dirname', $filesLockEx ) ); + // Try to lock those files for the scope of this function... + $scopeLockS = $this->getScopedFileLocks( $filesLockSh, LockManager::LOCK_UW, $status ); + $scopeLockE = $this->getScopedFileLocks( $filesLockEx, LockManager::LOCK_EX, $status ); + if ( !$status->isOK() ) { + wfProfileOut( __METHOD__ ); + return $status; // abort + } + } + + // Clear any cache entries (after locks acquired) + $this->clearCache(); + + // Actually attempt the operation batch... + $subStatus = FileOp::attemptBatch( $performOps, $opts ); + + // Merge errors into status fields + $status->merge( $subStatus ); + $status->success = $subStatus->success; // not done in merge() + + wfProfileOut( __METHOD__ ); + return $status; + } + + /** + * @see FileBackend::clearCache() + */ + final public function clearCache( array $paths = null ) { + if ( is_array( $paths ) ) { + $paths = array_map( 'FileBackend::normalizeStoragePath', $paths ); + $paths = array_filter( $paths, 'strlen' ); // remove nulls + } + if ( $paths === null ) { + $this->cache = array(); + $this->expensiveCache = array(); + } else { + foreach ( $paths as $path ) { + unset( $this->cache[$path] ); + unset( $this->expensiveCache[$path] ); + } + } + $this->doClearCache( $paths ); + } + + /** + * Clears any additional stat caches for storage paths + * + * @see FileBackend::clearCache() + * + * @param $paths Array Storage paths (optional) + * @return void + */ + protected function doClearCache( array $paths = null ) {} + + /** + * Prune the inexpensive cache if it is too big to add an item + * + * @return void + */ + protected function trimCache() { + if ( count( $this->cache ) >= $this->maxCacheSize ) { + reset( $this->cache ); + unset( $this->cache[key( $this->cache )] ); + } + } + + /** + * Prune the expensive cache if it is too big to add an item + * + * @return void + */ + protected function trimExpensiveCache() { + if ( count( $this->expensiveCache ) >= $this->maxExpensiveCacheSize ) { + reset( $this->expensiveCache ); + unset( $this->expensiveCache[key( $this->expensiveCache )] ); + } + } + + /** + * Check if a container name is valid. + * This checks for for length and illegal characters. + * + * @param $container string + * @return bool + */ + final protected static function isValidContainerName( $container ) { + // This accounts for Swift and S3 restrictions while leaving room + // for things like '.xxx' (hex shard chars) or '.seg' (segments). + // This disallows directory separators or traversal characters. + // Note that matching strings URL encode to the same string; + // in Swift, the length restriction is *after* URL encoding. + return preg_match( '/^[a-z0-9][a-z0-9-_]{0,199}$/i', $container ); + } + + /** + * Splits a storage path into an internal container name, + * an internal relative file name, and a container shard suffix. + * Any shard suffix is already appended to the internal container name. + * This also checks that the storage path is valid and within this backend. + * + * If the container is sharded but a suffix could not be determined, + * this means that the path can only refer to a directory and can only + * be scanned by looking in all the container shards. + * + * @param $storagePath string + * @return Array (container, path, container suffix) or (null, null, null) if invalid + */ + final protected function resolveStoragePath( $storagePath ) { + list( $backend, $container, $relPath ) = self::splitStoragePath( $storagePath ); + if ( $backend === $this->name ) { // must be for this backend + $relPath = self::normalizeContainerPath( $relPath ); + if ( $relPath !== null ) { + // Get shard for the normalized path if this container is sharded + $cShard = $this->getContainerShard( $container, $relPath ); + // Validate and sanitize the relative path (backend-specific) + $relPath = $this->resolveContainerPath( $container, $relPath ); + if ( $relPath !== null ) { + // Prepend any wiki ID prefix to the container name + $container = $this->fullContainerName( $container ); + if ( self::isValidContainerName( $container ) ) { + // Validate and sanitize the container name (backend-specific) + $container = $this->resolveContainerName( "{$container}{$cShard}" ); + if ( $container !== null ) { + return array( $container, $relPath, $cShard ); + } + } + } + } + } + return array( null, null, null ); + } + + /** + * Like resolveStoragePath() except null values are returned if + * the container is sharded and the shard could not be determined. + * + * @see FileBackendStore::resolveStoragePath() + * + * @param $storagePath string + * @return Array (container, path) or (null, null) if invalid + */ + final protected function resolveStoragePathReal( $storagePath ) { + list( $container, $relPath, $cShard ) = $this->resolveStoragePath( $storagePath ); + if ( $cShard !== null ) { + return array( $container, $relPath ); + } + return array( null, null ); + } + + /** + * Get the container name shard suffix for a given path. + * Any empty suffix means the container is not sharded. + * + * @param $container string Container name + * @param $relStoragePath string Storage path relative to the container + * @return string|null Returns null if shard could not be determined + */ + final protected function getContainerShard( $container, $relPath ) { + list( $levels, $base, $repeat ) = $this->getContainerHashLevels( $container ); + if ( $levels == 1 || $levels == 2 ) { + // Hash characters are either base 16 or 36 + $char = ( $base == 36 ) ? '[0-9a-z]' : '[0-9a-f]'; + // Get a regex that represents the shard portion of paths. + // The concatenation of the captures gives us the shard. + if ( $levels === 1 ) { // 16 or 36 shards per container + $hashDirRegex = '(' . $char . ')'; + } else { // 256 or 1296 shards per container + if ( $repeat ) { // verbose hash dir format (e.g. "a/ab/abc") + $hashDirRegex = $char . '/(' . $char . '{2})'; + } else { // short hash dir format (e.g. "a/b/c") + $hashDirRegex = '(' . $char . ')/(' . $char . ')'; + } + } + // Allow certain directories to be above the hash dirs so as + // to work with FileRepo (e.g. "archive/a/ab" or "temp/a/ab"). + // They must be 2+ chars to avoid any hash directory ambiguity. + $m = array(); + if ( preg_match( "!^(?:[^/]{2,}/)*$hashDirRegex(?:/|$)!", $relPath, $m ) ) { + return '.' . implode( '', array_slice( $m, 1 ) ); + } + return null; // failed to match + } + return ''; // no sharding + } + + /** + * Get the sharding config for a container. + * If greater than 0, then all file storage paths within + * the container are required to be hashed accordingly. + * + * @param $container string + * @return Array (integer levels, integer base, repeat flag) or (0, 0, false) + */ + final protected function getContainerHashLevels( $container ) { + if ( isset( $this->shardViaHashLevels[$container] ) ) { + $config = $this->shardViaHashLevels[$container]; + $hashLevels = (int)$config['levels']; + if ( $hashLevels == 1 || $hashLevels == 2 ) { + $hashBase = (int)$config['base']; + if ( $hashBase == 16 || $hashBase == 36 ) { + return array( $hashLevels, $hashBase, $config['repeat'] ); + } + } + } + return array( 0, 0, false ); // no sharding + } + + /** + * Get a list of full container shard suffixes for a container + * + * @param $container string + * @return Array + */ + final protected function getContainerSuffixes( $container ) { + $shards = array(); + list( $digits, $base ) = $this->getContainerHashLevels( $container ); + if ( $digits > 0 ) { + $numShards = pow( $base, $digits ); + for ( $index = 0; $index < $numShards; $index++ ) { + $shards[] = '.' . wfBaseConvert( $index, 10, $base, $digits ); + } + } + return $shards; + } + + /** + * Get the full container name, including the wiki ID prefix + * + * @param $container string + * @return string + */ + final protected function fullContainerName( $container ) { + if ( $this->wikiId != '' ) { + return "{$this->wikiId}-$container"; + } else { + return $container; + } + } + + /** + * Resolve a container name, checking if it's allowed by the backend. + * This is intended for internal use, such as encoding illegal chars. + * Subclasses can override this to be more restrictive. + * + * @param $container string + * @return string|null + */ + protected function resolveContainerName( $container ) { + return $container; + } + + /** + * Resolve a relative storage path, checking if it's allowed by the backend. + * This is intended for internal use, such as encoding illegal chars or perhaps + * getting absolute paths (e.g. FS based backends). Note that the relative path + * may be the empty string (e.g. the path is simply to the container). + * + * @param $container string Container name + * @param $relStoragePath string Storage path relative to the container + * @return string|null Path or null if not valid + */ + protected function resolveContainerPath( $container, $relStoragePath ) { + return $relStoragePath; + } +} + +/** + * FileBackendStore helper function to handle file listings that span container shards. + * Do not use this class from places outside of FileBackendStore. + * + * @ingroup FileBackend + */ +class FileBackendStoreShardListIterator implements Iterator { + /* @var FileBackendStore */ + protected $backend; + /* @var Array */ + protected $params; + /* @var Array */ + protected $shardSuffixes; + protected $container; // string + protected $directory; // string + + /* @var Traversable */ + protected $iter; + protected $curShard = 0; // integer + protected $pos = 0; // integer + + /** + * @param $backend FileBackendStore + * @param $container string Full storage container name + * @param $dir string Storage directory relative to container + * @param $suffixes Array List of container shard suffixes + * @param $params Array + */ + public function __construct( + FileBackendStore $backend, $container, $dir, array $suffixes, array $params + ) { + $this->backend = $backend; + $this->container = $container; + $this->directory = $dir; + $this->shardSuffixes = $suffixes; + $this->params = $params; + } + + public function current() { + if ( is_array( $this->iter ) ) { + return current( $this->iter ); + } else { + return $this->iter->current(); + } + } + + public function key() { + return $this->pos; + } + + public function next() { + ++$this->pos; + if ( is_array( $this->iter ) ) { + next( $this->iter ); + } else { + $this->iter->next(); + } + // Find the next non-empty shard if no elements are left + $this->nextShardIteratorIfNotValid(); + } + + /** + * If the iterator for this container shard is out of items, + * then move on to the next container that has items. + * If there are none, then it advances to the last container. + */ + protected function nextShardIteratorIfNotValid() { + while ( !$this->valid() ) { + if ( ++$this->curShard >= count( $this->shardSuffixes ) ) { + break; // no more container shards + } + $this->setIteratorFromCurrentShard(); + } + } + + protected function setIteratorFromCurrentShard() { + $suffix = $this->shardSuffixes[$this->curShard]; + $this->iter = $this->backend->getFileListInternal( + "{$this->container}{$suffix}", $this->directory, $this->params ); + } + + public function rewind() { + $this->pos = 0; + $this->curShard = 0; + $this->setIteratorFromCurrentShard(); + // Find the next non-empty shard if this one has no elements + $this->nextShardIteratorIfNotValid(); + } + + public function valid() { + if ( $this->iter == null ) { + return false; // some failure? + } elseif ( is_array( $this->iter ) ) { + return ( current( $this->iter ) !== false ); // no paths can have this value + } else { + return $this->iter->valid(); + } + } +} |