handle cases where SharedStorage::init isn't initializing the storage

Signed-off-by: Robin Appelman <robin@icewind.nl>

apps/files_sharing/lib/SharedStorage.php

@@ -55,11 +55,16 @@
 use OCP\IUserManager;
 use OCP\Lock\ILockingProvider;
 use OCP\Share\IShare;
+use Psr\Log\LoggerInterface;
 
 /**
  * Convert target path to source path and pass the function call to the correct storage provider
  */
 class SharedStorage extends \OC\Files\Storage\Wrapper\Jail implements ISharedStorage, IDisableEncryptionStorage {
+	/**
+	 * @var \OC\Files\Storage\Storage|null $storage
+	 */
+	protected $storage;
 
 	/** @var \OCP\Share\IShare */
 	private $superShare;
@@ -200,7 +205,17 @@ public function instanceOfStorage($class): bool {
 		])) {
 			return false;
 		}
-		return parent::instanceOfStorage($class);
+		if (ltrim($class, '\\') === 'OC\Files\Storage\Shared') {
+			// FIXME Temporary fix to keep existing checks working
+			$class = '\OCA\Files_Sharing\SharedStorage';
+		}
+		if (is_a($this, $class)) {
+			return true;
+		}
+
+		$storage = $this->getWrapperStorage();
+
+		return $storage->instanceOfStorage($class);
 	}
 
 	/**
@@ -532,6 +547,16 @@ public function getSourceStorage() {
 
 	public function getWrapperStorage() {
 		$this->init();
+
+		// `init` should handle this, but apparently it sometimes doesn't
+		if (!$this->storage instanceof IStorage) {
+			$e = new \Exception('Share source storage is null after initializing for share: ' . $this->getShare()->getId());
+			$this->storage = new FailedStorage(['exception' => $e]);
+			$this->cache = new FailedCache();
+			$this->rootPath = '';
+			$this->logger->logException($e);
+		}
+
 		return $this->storage;
 	}