--- /dev/null
+<?php
+/**
+ * Helper class for representing operations with transaction support.
+ *
+ * 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
+ */
+use Psr\Log\LoggerInterface;
+
+/**
+ * FileBackend helper class for representing operations.
+ * Do not use this class from places outside FileBackend.
+ *
+ * Methods called from FileOpBatch::attempt() should avoid throwing
+ * exceptions at all costs. FileOp objects should be lightweight in order
+ * to support large arrays in memory and serialization.
+ *
+ * @ingroup FileBackend
+ * @since 1.19
+ */
+abstract class FileOp {
+ /** @var array */
+ protected $params = [];
+
+ /** @var FileBackendStore */
+ protected $backend;
+ /** @var LoggerInterface */
+ protected $logger;
+
+ /** @var int */
+ protected $state = self::STATE_NEW;
+
+ /** @var bool */
+ protected $failed = false;
+
+ /** @var bool */
+ protected $async = false;
+
+ /** @var string */
+ protected $batchId;
+
+ /** @var bool Operation is not a no-op */
+ protected $doOperation = true;
+
+ /** @var string */
+ protected $sourceSha1;
+
+ /** @var bool */
+ protected $overwriteSameCase;
+
+ /** @var bool */
+ protected $destExists;
+
+ /* Object life-cycle */
+ const STATE_NEW = 1;
+ const STATE_CHECKED = 2;
+ const STATE_ATTEMPTED = 3;
+
+ /**
+ * Build a new batch file operation transaction
+ *
+ * @param FileBackendStore $backend
+ * @param array $params
+ * @param LoggerInterface $logger PSR logger instance
+ * @throws FileBackendError
+ */
+ final public function __construct(
+ FileBackendStore $backend, array $params, LoggerInterface $logger
+ ) {
+ $this->backend = $backend;
+ $this->logger = $logger;
+ list( $required, $optional, $paths ) = $this->allowedParams();
+ foreach ( $required as $name ) {
+ if ( isset( $params[$name] ) ) {
+ $this->params[$name] = $params[$name];
+ } else {
+ throw new InvalidArgumentException( "File operation missing parameter '$name'." );
+ }
+ }
+ foreach ( $optional as $name ) {
+ if ( isset( $params[$name] ) ) {
+ $this->params[$name] = $params[$name];
+ }
+ }
+ foreach ( $paths as $name ) {
+ if ( isset( $this->params[$name] ) ) {
+ // Normalize paths so the paths to the same file have the same string
+ $this->params[$name] = self::normalizeIfValidStoragePath( $this->params[$name] );
+ }
+ }
+ }
+
+ /**
+ * Normalize a string if it is a valid storage path
+ *
+ * @param string $path
+ * @return string
+ */
+ protected static function normalizeIfValidStoragePath( $path ) {
+ if ( FileBackend::isStoragePath( $path ) ) {
+ $res = FileBackend::normalizeStoragePath( $path );
+
+ return ( $res !== null ) ? $res : $path;
+ }
+
+ return $path;
+ }
+
+ /**
+ * Set the batch UUID this operation belongs to
+ *
+ * @param string $batchId
+ */
+ final public function setBatchId( $batchId ) {
+ $this->batchId = $batchId;
+ }
+
+ /**
+ * Get the value of the parameter with the given name
+ *
+ * @param string $name
+ * @return mixed Returns null if the parameter is not set
+ */
+ final public function getParam( $name ) {
+ return isset( $this->params[$name] ) ? $this->params[$name] : null;
+ }
+
+ /**
+ * Check if this operation failed precheck() or attempt()
+ *
+ * @return bool
+ */
+ final public function failed() {
+ return $this->failed;
+ }
+
+ /**
+ * Get a new empty predicates array for precheck()
+ *
+ * @return array
+ */
+ final public static function newPredicates() {
+ return [ 'exists' => [], 'sha1' => [] ];
+ }
+
+ /**
+ * Get a new empty dependency tracking array for paths read/written to
+ *
+ * @return array
+ */
+ final public static function newDependencies() {
+ return [ 'read' => [], 'write' => [] ];
+ }
+
+ /**
+ * Update a dependency tracking array to account for this operation
+ *
+ * @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
+ * @return array
+ */
+ final public function applyDependencies( array $deps ) {
+ $deps['read'] += array_fill_keys( $this->storagePathsRead(), 1 );
+ $deps['write'] += array_fill_keys( $this->storagePathsChanged(), 1 );
+
+ return $deps;
+ }
+
+ /**
+ * Check if this operation changes files listed in $paths
+ *
+ * @param array $deps Prior path reads/writes; format of FileOp::newPredicates()
+ * @return bool
+ */
+ final public function dependsOn( array $deps ) {
+ foreach ( $this->storagePathsChanged() as $path ) {
+ if ( isset( $deps['read'][$path] ) || isset( $deps['write'][$path] ) ) {
+ return true; // "output" or "anti" dependency
+ }
+ }
+ foreach ( $this->storagePathsRead() as $path ) {
+ if ( isset( $deps['write'][$path] ) ) {
+ return true; // "flow" dependency
+ }
+ }
+
+ return false;
+ }
+
+ /**
+ * Get the file journal entries for this file operation
+ *
+ * @param array $oPredicates Pre-op info about files (format of FileOp::newPredicates)
+ * @param array $nPredicates Post-op info about files (format of FileOp::newPredicates)
+ * @return array
+ */
+ final public function getJournalEntries( array $oPredicates, array $nPredicates ) {
+ if ( !$this->doOperation ) {
+ return []; // this is a no-op
+ }
+ $nullEntries = [];
+ $updateEntries = [];
+ $deleteEntries = [];
+ $pathsUsed = array_merge( $this->storagePathsRead(), $this->storagePathsChanged() );
+ foreach ( array_unique( $pathsUsed ) as $path ) {
+ $nullEntries[] = [ // assertion for recovery
+ 'op' => 'null',
+ 'path' => $path,
+ 'newSha1' => $this->fileSha1( $path, $oPredicates )
+ ];
+ }
+ foreach ( $this->storagePathsChanged() as $path ) {
+ if ( $nPredicates['sha1'][$path] === false ) { // deleted
+ $deleteEntries[] = [
+ 'op' => 'delete',
+ 'path' => $path,
+ 'newSha1' => ''
+ ];
+ } else { // created/updated
+ $updateEntries[] = [
+ 'op' => $this->fileExists( $path, $oPredicates ) ? 'update' : 'create',
+ 'path' => $path,
+ 'newSha1' => $nPredicates['sha1'][$path]
+ ];
+ }
+ }
+
+ return array_merge( $nullEntries, $updateEntries, $deleteEntries );
+ }
+
+ /**
+ * Check preconditions of the operation without writing anything.
+ * This must update $predicates for each path that the op can change
+ * except when a failing StatusValue object is returned.
+ *
+ * @param array &$predicates
+ * @return StatusValue
+ */
+ final public function precheck( array &$predicates ) {
+ if ( $this->state !== self::STATE_NEW ) {
+ return StatusValue::newFatal( 'fileop-fail-state', self::STATE_NEW, $this->state );
+ }
+ $this->state = self::STATE_CHECKED;
+ $status = $this->doPrecheck( $predicates );
+ if ( !$status->isOK() ) {
+ $this->failed = true;
+ }
+
+ return $status;
+ }
+
+ /**
+ * @param array &$predicates
+ * @return StatusValue
+ */
+ protected function doPrecheck( array &$predicates ) {
+ return StatusValue::newGood();
+ }
+
+ /**
+ * Attempt the operation
+ *
+ * @return StatusValue
+ */
+ final public function attempt() {
+ if ( $this->state !== self::STATE_CHECKED ) {
+ return StatusValue::newFatal( 'fileop-fail-state', self::STATE_CHECKED, $this->state );
+ } elseif ( $this->failed ) { // failed precheck
+ return StatusValue::newFatal( 'fileop-fail-attempt-precheck' );
+ }
+ $this->state = self::STATE_ATTEMPTED;
+ if ( $this->doOperation ) {
+ $status = $this->doAttempt();
+ if ( !$status->isOK() ) {
+ $this->failed = true;
+ $this->logFailure( 'attempt' );
+ }
+ } else { // no-op
+ $status = StatusValue::newGood();
+ }
+
+ return $status;
+ }
+
+ /**
+ * @return StatusValue
+ */
+ protected function doAttempt() {
+ return StatusValue::newGood();
+ }
+
+ /**
+ * Attempt the operation in the background
+ *
+ * @return StatusValue
+ */
+ final public function attemptAsync() {
+ $this->async = true;
+ $result = $this->attempt();
+ $this->async = false;
+
+ return $result;
+ }
+
+ /**
+ * Get the file operation parameters
+ *
+ * @return array (required params list, optional params list, list of params that are paths)
+ */
+ protected function allowedParams() {
+ return [ [], [], [] ];
+ }
+
+ /**
+ * Adjust params to FileBackendStore internal file calls
+ *
+ * @param array $params
+ * @return array (required params list, optional params list)
+ */
+ protected function setFlags( array $params ) {
+ return [ 'async' => $this->async ] + $params;
+ }
+
+ /**
+ * Get a list of storage paths read from for this operation
+ *
+ * @return array
+ */
+ public function storagePathsRead() {
+ return [];
+ }
+
+ /**
+ * Get a list of storage paths written to for this operation
+ *
+ * @return array
+ */
+ public function storagePathsChanged() {
+ return [];
+ }
+
+ /**
+ * Check for errors with regards to the destination file already existing.
+ * Also set the destExists, overwriteSameCase and sourceSha1 member variables.
+ * A bad StatusValue will be returned if there is no chance it can be overwritten.
+ *
+ * @param array $predicates
+ * @return StatusValue
+ */
+ protected function precheckDestExistence( array $predicates ) {
+ $status = StatusValue::newGood();
+ // Get hash of source file/string and the destination file
+ $this->sourceSha1 = $this->getSourceSha1Base36(); // FS file or data string
+ if ( $this->sourceSha1 === null ) { // file in storage?
+ $this->sourceSha1 = $this->fileSha1( $this->params['src'], $predicates );
+ }
+ $this->overwriteSameCase = false;
+ $this->destExists = $this->fileExists( $this->params['dst'], $predicates );
+ if ( $this->destExists ) {
+ if ( $this->getParam( 'overwrite' ) ) {
+ return $status; // OK
+ } elseif ( $this->getParam( 'overwriteSame' ) ) {
+ $dhash = $this->fileSha1( $this->params['dst'], $predicates );
+ // Check if hashes are valid and match each other...
+ if ( !strlen( $this->sourceSha1 ) || !strlen( $dhash ) ) {
+ $status->fatal( 'backend-fail-hashes' );
+ } elseif ( $this->sourceSha1 !== $dhash ) {
+ // Give an error if the files are not identical
+ $status->fatal( 'backend-fail-notsame', $this->params['dst'] );
+ } else {
+ $this->overwriteSameCase = true; // OK
+ }
+
+ return $status; // do nothing; either OK or bad status
+ } else {
+ $status->fatal( 'backend-fail-alreadyexists', $this->params['dst'] );
+
+ return $status;
+ }
+ }
+
+ return $status;
+ }
+
+ /**
+ * precheckDestExistence() helper function to get the source file SHA-1.
+ * Subclasses should overwride this if the source is not in storage.
+ *
+ * @return string|bool Returns false on failure
+ */
+ protected function getSourceSha1Base36() {
+ return null; // N/A
+ }
+
+ /**
+ * Check if a file will exist in storage when this operation is attempted
+ *
+ * @param string $source Storage path
+ * @param array $predicates
+ * @return bool
+ */
+ final protected function fileExists( $source, array $predicates ) {
+ if ( isset( $predicates['exists'][$source] ) ) {
+ return $predicates['exists'][$source]; // previous op assures this
+ } else {
+ $params = [ 'src' => $source, 'latest' => true ];
+
+ return $this->backend->fileExists( $params );
+ }
+ }
+
+ /**
+ * Get the SHA-1 of a file in storage when this operation is attempted
+ *
+ * @param string $source Storage path
+ * @param array $predicates
+ * @return string|bool False on failure
+ */
+ final protected function fileSha1( $source, array $predicates ) {
+ if ( isset( $predicates['sha1'][$source] ) ) {
+ return $predicates['sha1'][$source]; // previous op assures this
+ } elseif ( isset( $predicates['exists'][$source] ) && !$predicates['exists'][$source] ) {
+ return false; // previous op assures this
+ } else {
+ $params = [ 'src' => $source, 'latest' => true ];
+
+ return $this->backend->getFileSha1Base36( $params );
+ }
+ }
+
+ /**
+ * Get the backend this operation is for
+ *
+ * @return FileBackendStore
+ */
+ public function getBackend() {
+ return $this->backend;
+ }
+
+ /**
+ * Log a file operation failure and preserve any temp files
+ *
+ * @param string $action
+ */
+ final public function logFailure( $action ) {
+ $params = $this->params;
+ $params['failedAction'] = $action;
+ try {
+ $this->logger->error( static::class .
+ " failed (batch #{$this->batchId}): " . FormatJson::encode( $params ) );
+ } catch ( Exception $e ) {
+ // bad config? debug log error?
+ }
+ }
+}
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