fix: try to find non-recursive share source

instead of always picking the first one, try to find one that won't blow up

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

[skip ci]

Author: icewind1991

apps/files_sharing/lib/SharedStorage.php

@@ -180,12 +180,23 @@ private function init() {
 				$this->cache = new FailedCache();
 				$this->rootPath = '';
 			} else {
-				$this->nonMaskedStorage = $ownerNode->getStorage();
-				if ($this->nonMaskedStorage instanceof Wrapper && $this->nonMaskedStorage->isWrapperOf($this)) {
+				foreach ($ownerNodes as $ownerNode) {
+					$nonMaskedStorage = $ownerNode->getStorage();
+
+					// check if potential source node would lead to a recursive share setup
+					if ($nonMaskedStorage instanceof Wrapper && $nonMaskedStorage->isWrapperOf($this)) {
+						continue;
+					}
+					$this->nonMaskedStorage = $nonMaskedStorage;
+					$this->sourcePath = $ownerNode->getPath();
+					$this->rootPath = $ownerNode->getInternalPath();
+					$this->cache = null;
+					break;
+				}
+				if (!$this->nonMaskedStorage) {
+					// all potential source nodes would have been recursive
 					throw new \Exception('recursive share detected');
 				}
-				$this->sourcePath = $ownerNode->getPath();
-				$this->rootPath = $ownerNode->getInternalPath();
 				$this->storage = new PermissionsMask([
 					'storage' => $this->nonMaskedStorage,
 					'mask' => $this->superShare->getPermissions(),