add some recrusive detection/prevention

apps/files_external/tests/Storage/SmbTest.php

@@ -105,6 +105,7 @@ public function testNotifyGetChanges() {
 		$this->instance->unlink('/renamed.txt');
 		sleep(1); //time for all changes to be processed
 
+		/** @var IChange[] $changes */
 		$changes = [];
 		$count = 0;
 		// wait up to 10 seconds for incoming changes
@@ -115,14 +116,23 @@ public function testNotifyGetChanges() {
 		}
 		$notifyHandler->stop();
 
-		$expected = [
-			new Change(IChange::ADDED, 'newfile.txt'),
-			new RenameChange(IChange::RENAMED, 'newfile.txt', 'renamed.txt'),
-			new Change(IChange::REMOVED, 'renamed.txt')
-		];
+		// depending on the server environment, the initial create might be detected as a change instead
+		if ($changes[0]->getType() === IChange::MODIFIED) {
+			$expected = [
+				new Change(IChange::MODIFIED, 'newfile.txt'),
+				new RenameChange(IChange::RENAMED, 'newfile.txt', 'renamed.txt'),
+				new Change(IChange::REMOVED, 'renamed.txt')
+			];
+		} else {
+			$expected = [
+				new Change(IChange::ADDED, 'newfile.txt'),
+				new RenameChange(IChange::RENAMED, 'newfile.txt', 'renamed.txt'),
+				new Change(IChange::REMOVED, 'renamed.txt')
+			];
+		}
 
 		foreach ($expected as $expectedChange) {
-			$this->assertTrue(in_array($expectedChange, $changes), 'Actual changes are:' . PHP_EOL . print_r($changes, true) . PHP_EOL . 'Expected to find: ' . PHP_EOL . print_r($expectedChange, true));
+			$this->assertTrue(in_array($expectedChange, $changes), "Expected changes are:\n" . print_r($expected, true) . PHP_EOL . 'Expected to find: ' . PHP_EOL . print_r($expectedChange, true) . "\nGot:\n" . print_r($changes, true));
 		}
 	}
 
@@ -141,7 +151,12 @@ public function testNotifyListen() {
 			return false;//stop listening
 		});
 
-		$this->assertEquals(new Change(IChange::ADDED, 'newfile.txt'), $result);
+		// depending on the server environment, the initial create might be detected as a change instead
+		if ($result->getType() === IChange::ADDED) {
+			$this->assertEquals(new Change(IChange::ADDED, 'newfile.txt'), $result);
+		} else {
+			$this->assertEquals(new Change(IChange::MODIFIED, 'newfile.txt'), $result);
+		}
 	}
 
 	public function testRenameRoot() {

apps/files_sharing/lib/SharedStorage.php

@@ -41,6 +41,7 @@
 use OC\Files\Storage\FailedStorage;
 use OC\Files\Storage\Home;
 use OC\Files\Storage\Wrapper\PermissionsMask;
+use OC\Files\Storage\Wrapper\Wrapper;
 use OC\User\NoUserException;
 use OCA\Files_External\Config\ConfigAdapter;
 use OCP\Constants;
@@ -97,6 +98,8 @@ class SharedStorage extends \OC\Files\Storage\Wrapper\Jail implements ISharedSto
 
 	private string $sourcePath = '';
 
+	private static int $initDepth = 0;
+
 	public function __construct($arguments) {
 		$this->ownerView = $arguments['ownerView'];
 		$this->logger = \OC::$server->get(LoggerInterface::class);
@@ -136,8 +139,15 @@ private function init() {
 		if ($this->initialized) {
 			return;
 		}
+
 		$this->initialized = true;
+		self::$initDepth++;
+
 		try {
+			if (self::$initDepth > 10) {
+				throw new \Exception("Maximum share depth reached");
+			}
+
 			/** @var IRootFolder $rootFolder */
 			$rootFolder = \OC::$server->get(IRootFolder::class);
 			$this->ownerUserFolder = $rootFolder->getUserFolder($this->superShare->getShareOwner());
@@ -148,6 +158,9 @@ private function init() {
 				$this->cache = new FailedCache();
 				$this->rootPath = '';
 			} else {
+				if ($this->nonMaskedStorage instanceof Wrapper && $this->nonMaskedStorage->isWrapperOf($this)) {
+					throw new \Exception('recursive share detected');
+				}
 				$this->nonMaskedStorage = $ownerNode->getStorage();
 				$this->sourcePath = $ownerNode->getPath();
 				$this->rootPath = $ownerNode->getInternalPath();
@@ -176,6 +189,7 @@ private function init() {
 		if (!$this->nonMaskedStorage) {
 			$this->nonMaskedStorage = $this->storage;
 		}
+		self::$initDepth--;
 	}
 
 	/**
@@ -409,7 +423,7 @@ public function getCache($path = '', $storage = null) {
 			return new FailedCache();
 		}
 
-		$this->cache = new Cache(
+		$this->cache = new \OCA\Files_Sharing\Cache(
 			$storage,
 			$sourceRoot,
 			\OC::$server->get(CacheDependencies::class),

lib/private/Files/Storage/Wrapper/Wrapper.php

@@ -654,4 +654,15 @@ public function writeStream(string $path, $stream, int $size = null): int {
 	public function getDirectoryContent($directory): \Traversable {
 		return $this->getWrapperStorage()->getDirectoryContent($directory);
 	}
+
+	public function isWrapperOf(IStorage $storage) {
+		$wrapped = $this->getWrapperStorage();
+		if ($wrapped === $storage) {
+			return true;
+		}
+		if ($wrapped instanceof Wrapper) {
+			return $wrapped->isWrapperOf($storage);
+		}
+		return false;
+	}
 }