Adding repair step for sub share

Adding repair step for sub share.
When share table due to some magic gets
duplicate entries ( except the id or primary
key ), then this repair step comes for rescue.

Signed-off-by: Sujith H <sharidasan@owncloud.com>

lib/private/Repair.php

@@ -37,6 +37,7 @@
 use OC\Repair\OldGroupMembershipShares;
 use OC\Repair\RemoveGetETagEntries;
 use OC\Repair\RemoveRootShares;
+use OC\Repair\RepairSubShares;
 use OC\Repair\SharePropagation;
 use OC\Repair\SqliteAutoincrement;
 use OC\Repair\DropOldTables;
@@ -157,6 +158,10 @@ public static function getRepairSteps() {
 				\OC::$server->getConfig(),
 				\OC::$server->getAppConfig()
 			),
+			new RepairSubShares(
+				\OC::$server->getConfig(),
+				\OC::$server->getDatabaseConnection()
+			),
 		];
 	}
 

lib/private/Repair/RepairSubShares.php

@@ -0,0 +1,106 @@
+<?php
+/**
+ * @author Sujith Haridasan <sharidasan@owncloud.com>
+ *
+ * @copyright Copyright (c) 2018, ownCloud GmbH
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Repair;
+
+use OCP\DB\QueryBuilder\IQueryBuilder;
+use OCP\IConfig;
+use OCP\IDBConnection;
+use OCP\Migration\IOutput;
+use OCP\Migration\IRepairStep;
+
+class RepairSubShares implements IRepairStep {
+
+	private $connection;
+
+	private $config;
+
+	/** @var  IQueryBuilder */
+	private $getDuplicateRows;
+
+	/** @var  IQueryBuilder */
+	private $deleteShareId;
+
+	public function __construct(
+		IConfig $config,
+		IDBConnection $connection) {
+		$this->config = $config;
+		$this->connection = $connection;
+	}
+
+	public function getName() {
+		return "Repair sub shares";
+	}
+
+	/**
+	 * Remove duplicate rows.
+	 * i.e, except id all columns are same for oc_share
+	 */
+	private function removeRowsWithDuplicateDataExceptId() {
+		/**
+		 * Retrieves the duplicate rows with different id's
+		 * of oc_share
+		 */
+		$builder = $this->connection->getQueryBuilder();
+		$builder
+			->select('id', 'parent', $builder->createFunction('count(*)'))
+			->from('share')
+			->where($builder->expr()->eq('share_type', '2'))
+			->groupBy('parent')
+			->addGroupBy('share_with')
+			->having('count(*) > 1')->setMaxResults(1000);
+
+		$this->getDuplicateRows = $builder;
+
+		$builder = $this->connection->getQueryBuilder();
+		$builder
+			->delete('share')
+			->where($builder->expr()->eq('id', $builder->createParameter('shareId')));
+
+		$this->deleteShareId = $builder;
+	}
+
+	public function run(IOutput $output) {
+		$deletedEntries = 0;
+		$this->removeRowsWithDuplicateDataExceptId();
+
+		/**
+		 * Going for pagination because if there are 1 million rows
+		 * it wont be easy to scale the data
+		 */
+		do {
+			$results = $this->getDuplicateRows->execute();
+			$rows = $results->fetchAll();
+			$results->closeCursor();
+			$lastResultCount = 0;
+
+			foreach ($rows as $row) {
+				$deletedEntries += $this->deleteShareId->setParameter('shareId', (int) $row['id'])
+					->execute();
+				$lastResultCount++;
+			}
+		} while($lastResultCount > 0);
+
+		if ($deletedEntries > 0) {
+			$output->info('Removed ' . $deletedEntries . ' shares where duplicate rows where found');
+		}
+	}
+}