nextcloud / server

apps/files_external/lib/Lib/Storage/AmazonS3.php

Indentation +732 added lines, -732 removed lines

@@ -58,736 +58,736 @@
 use Psr\Log\LoggerInterface;
 
 class AmazonS3 extends \OC\Files\Storage\Common {
-	use S3ConnectionTrait;
-	use S3ObjectTrait;
-
-	private LoggerInterface $logger;
-
-	public function needsPartFile() {
-		return false;
-	}
-
-	/** @var CappedMemoryCache<array|false> */
-	private CappedMemoryCache $objectCache;
-
-	/** @var CappedMemoryCache<bool> */
-	private CappedMemoryCache $directoryCache;
-
-	/** @var CappedMemoryCache<array> */
-	private CappedMemoryCache $filesCache;
-
-	private IMimeTypeDetector $mimeDetector;
-	private ?bool $versioningEnabled = null;
-	private ICache $memCache;
-
-	public function __construct($parameters) {
-		parent::__construct($parameters);
-		$this->parseParams($parameters);
-		$this->id = 'amazon::external::' . md5($this->params['hostname'] . ':' . $this->params['bucket'] . ':' . $this->params['key']);
-		$this->objectCache = new CappedMemoryCache();
-		$this->directoryCache = new CappedMemoryCache();
-		$this->filesCache = new CappedMemoryCache();
-		$this->mimeDetector = Server::get(IMimeTypeDetector::class);
-		/** @var ICacheFactory $cacheFactory */
-		$cacheFactory = Server::get(ICacheFactory::class);
-		$this->memCache = $cacheFactory->createLocal('s3-external');
-		$this->logger = Server::get(LoggerInterface::class);
-	}
-
-	/**
-	 * @param string $path
-	 * @return string correctly encoded path
-	 */
-	private function normalizePath($path) {
-		$path = trim($path, '/');
-
-		if (!$path) {
-			$path = '.';
-		}
-
-		return $path;
-	}
-
-	private function isRoot($path) {
-		return $path === '.';
-	}
-
-	private function cleanKey($path) {
-		if ($this->isRoot($path)) {
-			return '/';
-		}
-		return $path;
-	}
-
-	private function clearCache() {
-		$this->objectCache = new CappedMemoryCache();
-		$this->directoryCache = new CappedMemoryCache();
-		$this->filesCache = new CappedMemoryCache();
-	}
-
-	private function invalidateCache($key) {
-		unset($this->objectCache[$key]);
-		$keys = array_keys($this->objectCache->getData());
-		$keyLength = strlen($key);
-		foreach ($keys as $existingKey) {
-			if (substr($existingKey, 0, $keyLength) === $key) {
-				unset($this->objectCache[$existingKey]);
-			}
-		}
-		unset($this->filesCache[$key]);
-		$keys = array_keys($this->directoryCache->getData());
-		$keyLength = strlen($key);
-		foreach ($keys as $existingKey) {
-			if (substr($existingKey, 0, $keyLength) === $key) {
-				unset($this->directoryCache[$existingKey]);
-			}
-		}
-		unset($this->directoryCache[$key]);
-	}
-
-	/**
-	 * @return array|false
-	 */
-	private function headObject(string $key) {
-		if (!isset($this->objectCache[$key])) {
-			try {
-				$this->objectCache[$key] = $this->getConnection()->headObject([
-					'Bucket' => $this->bucket,
-					'Key' => $key
-				])->toArray();
-			} catch (S3Exception $e) {
-				if ($e->getStatusCode() >= 500) {
-					throw $e;
-				}
-				$this->objectCache[$key] = false;
-			}
-		}
-
-		if (is_array($this->objectCache[$key]) && !isset($this->objectCache[$key]["Key"])) {
-			/** @psalm-suppress InvalidArgument Psalm doesn't understand nested arrays well */
-			$this->objectCache[$key]["Key"] = $key;
-		}
-		return $this->objectCache[$key];
-	}
-
-	/**
-	 * Return true if directory exists
-	 *
-	 * There are no folders in s3. A folder like structure could be archived
-	 * by prefixing files with the folder name.
-	 *
-	 * Implementation from flysystem-aws-s3-v3:
-	 * https://github.com/thephpleague/flysystem-aws-s3-v3/blob/8241e9cc5b28f981e0d24cdaf9867f14c7498ae4/src/AwsS3Adapter.php#L670-L694
-	 *
-	 * @param $path
-	 * @return bool
-	 * @throws \Exception
-	 */
-	private function doesDirectoryExist($path) {
-		if ($path === '.' || $path === '') {
-			return true;
-		}
-		$path = rtrim($path, '/') . '/';
-
-		if (isset($this->directoryCache[$path])) {
-			return $this->directoryCache[$path];
-		}
-		try {
-			// Maybe this isn't an actual key, but a prefix.
-			// Do a prefix listing of objects to determine.
-			$result = $this->getConnection()->listObjectsV2([
-				'Bucket' => $this->bucket,
-				'Prefix' => $path,
-				'MaxKeys' => 1,
-			]);
-
-			if (isset($result['Contents'])) {
-				$this->directoryCache[$path] = true;
-				return true;
-			}
-
-			// empty directories have their own object
-			$object = $this->headObject($path);
-
-			if ($object) {
-				$this->directoryCache[$path] = true;
-				return true;
-			}
-		} catch (S3Exception $e) {
-			if ($e->getStatusCode() >= 400 && $e->getStatusCode() < 500) {
-				$this->directoryCache[$path] = false;
-			}
-			throw $e;
-		}
-
-
-		$this->directoryCache[$path] = false;
-		return false;
-	}
-
-	/**
-	 * Remove a file or folder
-	 *
-	 * @param string $path
-	 * @return bool
-	 */
-	protected function remove($path) {
-		// remember fileType to reduce http calls
-		$fileType = $this->filetype($path);
-		if ($fileType === 'dir') {
-			return $this->rmdir($path);
-		} elseif ($fileType === 'file') {
-			return $this->unlink($path);
-		} else {
-			return false;
-		}
-	}
-
-	public function mkdir($path) {
-		$path = $this->normalizePath($path);
-
-		if ($this->is_dir($path)) {
-			return false;
-		}
-
-		try {
-			$this->getConnection()->putObject([
-				'Bucket' => $this->bucket,
-				'Key' => $path . '/',
-				'Body' => '',
-				'ContentType' => FileInfo::MIMETYPE_FOLDER
-			]);
-			$this->testTimeout();
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-
-		$this->invalidateCache($path);
-
-		return true;
-	}
-
-	public function file_exists($path) {
-		return $this->filetype($path) !== false;
-	}
-
-
-	public function rmdir($path) {
-		$path = $this->normalizePath($path);
-
-		if ($this->isRoot($path)) {
-			return $this->clearBucket();
-		}
-
-		if (!$this->file_exists($path)) {
-			return false;
-		}
-
-		$this->invalidateCache($path);
-		return $this->batchDelete($path);
-	}
-
-	protected function clearBucket() {
-		$this->clearCache();
-		return $this->batchDelete();
-	}
-
-	private function batchDelete($path = null) {
-		// TODO explore using https://docs.aws.amazon.com/aws-sdk-php/v3/api/class-Aws.S3.BatchDelete.html
-		$params = [
-			'Bucket' => $this->bucket
-		];
-		if ($path !== null) {
-			$params['Prefix'] = $path . '/';
-		}
-		try {
-			$connection = $this->getConnection();
-			// Since there are no real directories on S3, we need
-			// to delete all objects prefixed with the path.
-			do {
-				// instead of the iterator, manually loop over the list ...
-				$objects = $connection->listObjects($params);
-				// ... so we can delete the files in batches
-				if (isset($objects['Contents'])) {
-					$connection->deleteObjects([
-						'Bucket' => $this->bucket,
-						'Delete' => [
-							'Objects' => $objects['Contents']
-						]
-					]);
-					$this->testTimeout();
-				}
-				// we reached the end when the list is no longer truncated
-			} while ($objects['IsTruncated']);
-			if ($path !== '' && $path !== null) {
-				$this->deleteObject($path);
-			}
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-		return true;
-	}
-
-	public function opendir($path) {
-		try {
-			$content = iterator_to_array($this->getDirectoryContent($path));
-			return IteratorDirectory::wrap(array_map(function (array $item) {
-				return $item['name'];
-			}, $content));
-		} catch (S3Exception $e) {
-			return false;
-		}
-	}
-
-	public function stat($path) {
-		$path = $this->normalizePath($path);
-
-		if ($this->is_dir($path)) {
-			$stat = $this->getDirectoryMetaData($path);
-		} else {
-			$object = $this->headObject($path);
-			if ($object === false) {
-				return false;
-			}
-			$stat = $this->objectToMetaData($object);
-		}
-		$stat['atime'] = time();
-
-		return $stat;
-	}
-
-	/**
-	 * Return content length for object
-	 *
-	 * When the information is already present (e.g. opendir has been called before)
-	 * this value is return. Otherwise a headObject is emitted.
-	 *
-	 * @param $path
-	 * @return int|mixed
-	 */
-	private function getContentLength($path) {
-		if (isset($this->filesCache[$path])) {
-			return (int)$this->filesCache[$path]['ContentLength'];
-		}
-
-		$result = $this->headObject($path);
-		if (isset($result['ContentLength'])) {
-			return (int)$result['ContentLength'];
-		}
-
-		return 0;
-	}
-
-	/**
-	 * Return last modified for object
-	 *
-	 * When the information is already present (e.g. opendir has been called before)
-	 * this value is return. Otherwise a headObject is emitted.
-	 *
-	 * @param $path
-	 * @return mixed|string
-	 */
-	private function getLastModified($path) {
-		if (isset($this->filesCache[$path])) {
-			return $this->filesCache[$path]['LastModified'];
-		}
-
-		$result = $this->headObject($path);
-		if (isset($result['LastModified'])) {
-			return $result['LastModified'];
-		}
-
-		return 'now';
-	}
-
-	public function is_dir($path) {
-		$path = $this->normalizePath($path);
-
-		if (isset($this->filesCache[$path])) {
-			return false;
-		}
-
-		try {
-			return $this->doesDirectoryExist($path);
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-	}
-
-	public function filetype($path) {
-		$path = $this->normalizePath($path);
-
-		if ($this->isRoot($path)) {
-			return 'dir';
-		}
-
-		try {
-			if (isset($this->directoryCache[$path]) && $this->directoryCache[$path]) {
-				return 'dir';
-			}
-			if (isset($this->filesCache[$path]) || $this->headObject($path)) {
-				return 'file';
-			}
-			if ($this->doesDirectoryExist($path)) {
-				return 'dir';
-			}
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-
-		return false;
-	}
-
-	public function getPermissions($path) {
-		$type = $this->filetype($path);
-		if (!$type) {
-			return 0;
-		}
-		return $type === 'dir' ? Constants::PERMISSION_ALL : Constants::PERMISSION_ALL - Constants::PERMISSION_CREATE;
-	}
-
-	public function unlink($path) {
-		$path = $this->normalizePath($path);
-
-		if ($this->is_dir($path)) {
-			return $this->rmdir($path);
-		}
-
-		try {
-			$this->deleteObject($path);
-			$this->invalidateCache($path);
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-
-		return true;
-	}
-
-	public function fopen($path, $mode) {
-		$path = $this->normalizePath($path);
-
-		switch ($mode) {
-			case 'r':
-			case 'rb':
-				// Don't try to fetch empty files
-				$stat = $this->stat($path);
-				if (is_array($stat) && isset($stat['size']) && $stat['size'] === 0) {
-					return fopen('php://memory', $mode);
-				}
-
-				try {
-					return $this->readObject($path);
-				} catch (S3Exception $e) {
-					$this->logger->error($e->getMessage(), [
-						'app' => 'files_external',
-						'exception' => $e,
-					]);
-					return false;
-				}
-			case 'w':
-			case 'wb':
-				$tmpFile = \OC::$server->getTempManager()->getTemporaryFile();
-
-				$handle = fopen($tmpFile, 'w');
-				return CallbackWrapper::wrap($handle, null, null, function () use ($path, $tmpFile) {
-					$this->writeBack($tmpFile, $path);
-				});
-			case 'a':
-			case 'ab':
-			case 'r+':
-			case 'w+':
-			case 'wb+':
-			case 'a+':
-			case 'x':
-			case 'x+':
-			case 'c':
-			case 'c+':
-				if (strrpos($path, '.') !== false) {
-					$ext = substr($path, strrpos($path, '.'));
-				} else {
-					$ext = '';
-				}
-				$tmpFile = \OC::$server->getTempManager()->getTemporaryFile($ext);
-				if ($this->file_exists($path)) {
-					$source = $this->readObject($path);
-					file_put_contents($tmpFile, $source);
-				}
-
-				$handle = fopen($tmpFile, $mode);
-				return CallbackWrapper::wrap($handle, null, null, function () use ($path, $tmpFile) {
-					$this->writeBack($tmpFile, $path);
-				});
-		}
-		return false;
-	}
-
-	public function touch($path, $mtime = null) {
-		if (is_null($mtime)) {
-			$mtime = time();
-		}
-		$metadata = [
-			'lastmodified' => gmdate(\DateTime::RFC1123, $mtime)
-		];
-
-		try {
-			if (!$this->file_exists($path)) {
-				$mimeType = $this->mimeDetector->detectPath($path);
-				$this->getConnection()->putObject([
-					'Bucket' => $this->bucket,
-					'Key' => $this->cleanKey($path),
-					'Metadata' => $metadata,
-					'Body' => '',
-					'ContentType' => $mimeType,
-					'MetadataDirective' => 'REPLACE',
-				]);
-				$this->testTimeout();
-			}
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-
-		$this->invalidateCache($path);
-		return true;
-	}
-
-	public function copy($source, $target, $isFile = null) {
-		$source = $this->normalizePath($source);
-		$target = $this->normalizePath($target);
-
-		if ($isFile === true || $this->is_file($source)) {
-			try {
-				$this->getConnection()->copyObject([
-					'Bucket' => $this->bucket,
-					'Key' => $this->cleanKey($target),
-					'CopySource' => S3Client::encodeKey($this->bucket . '/' . $source)
-				]);
-				$this->testTimeout();
-			} catch (S3Exception $e) {
-				$this->logger->error($e->getMessage(), [
-					'app' => 'files_external',
-					'exception' => $e,
-				]);
-				return false;
-			}
-		} else {
-			$this->remove($target);
-
-			try {
-				$this->mkdir($target);
-				$this->testTimeout();
-			} catch (S3Exception $e) {
-				$this->logger->error($e->getMessage(), [
-					'app' => 'files_external',
-					'exception' => $e,
-				]);
-				return false;
-			}
-
-			foreach ($this->getDirectoryContent($source) as $item) {
-				$childSource = $source . '/' . $item['name'];
-				$childTarget = $target . '/' . $item['name'];
-				$this->copy($childSource, $childTarget, $item['mimetype'] !== FileInfo::MIMETYPE_FOLDER);
-			}
-		}
-
-		$this->invalidateCache($target);
-
-		return true;
-	}
-
-	public function rename($source, $target) {
-		$source = $this->normalizePath($source);
-		$target = $this->normalizePath($target);
-
-		if ($this->is_file($source)) {
-			if ($this->copy($source, $target) === false) {
-				return false;
-			}
-
-			if ($this->unlink($source) === false) {
-				$this->unlink($target);
-				return false;
-			}
-		} else {
-			if ($this->copy($source, $target) === false) {
-				return false;
-			}
-
-			if ($this->rmdir($source) === false) {
-				$this->rmdir($target);
-				return false;
-			}
-		}
-
-		return true;
-	}
-
-	public function test() {
-		$this->getConnection()->headBucket([
-			'Bucket' => $this->bucket
-		]);
-		return true;
-	}
-
-	public function getId() {
-		return $this->id;
-	}
-
-	public function writeBack($tmpFile, $path) {
-		try {
-			$source = fopen($tmpFile, 'r');
-			$this->writeObject($path, $source, $this->mimeDetector->detectPath($path));
-			$this->invalidateCache($path);
-
-			unlink($tmpFile);
-			return true;
-		} catch (S3Exception $e) {
-			$this->logger->error($e->getMessage(), [
-				'app' => 'files_external',
-				'exception' => $e,
-			]);
-			return false;
-		}
-	}
-
-	/**
-	 * check if curl is installed
-	 */
-	public static function checkDependencies() {
-		return true;
-	}
-
-	public function getDirectoryContent($directory): \Traversable {
-		$path = $this->normalizePath($directory);
-
-		if ($this->isRoot($path)) {
-			$path = '';
-		} else {
-			$path .= '/';
-		}
-
-		$results = $this->getConnection()->getPaginator('ListObjectsV2', [
-			'Bucket' => $this->bucket,
-			'Delimiter' => '/',
-			'Prefix' => $path,
-		]);
-
-		foreach ($results as $result) {
-			// sub folders
-			if (is_array($result['CommonPrefixes'])) {
-				foreach ($result['CommonPrefixes'] as $prefix) {
-					$dir = $this->getDirectoryMetaData($prefix['Prefix']);
-					if ($dir) {
-						yield $dir;
-					}
-				}
-			}
-			if (is_array($result['Contents'])) {
-				foreach ($result['Contents'] as $object) {
-					$this->objectCache[$object['Key']] = $object;
-					if ($object['Key'] !== $path) {
-						yield $this->objectToMetaData($object);
-					}
-				}
-			}
-		}
-	}
-
-	private function objectToMetaData(array $object): array {
-		return [
-			'name' => basename($object['Key']),
-			'mimetype' => $this->mimeDetector->detectPath($object['Key']),
-			'mtime' => strtotime($object['LastModified']),
-			'storage_mtime' => strtotime($object['LastModified']),
-			'etag' => $object['ETag'],
-			'permissions' => Constants::PERMISSION_ALL - Constants::PERMISSION_CREATE,
-			'size' => (int)($object['Size'] ?? $object['ContentLength']),
-		];
-	}
-
-	private function getDirectoryMetaData(string $path): ?array {
-		$path = trim($path, '/');
-		// when versioning is enabled, delete markers are returned as part of CommonPrefixes
-		// resulting in "ghost" folders, verify that each folder actually exists
-		if ($this->versioningEnabled() && !$this->doesDirectoryExist($path)) {
-			return null;
-		}
-		$cacheEntry = $this->getCache()->get($path);
-		if ($cacheEntry instanceof CacheEntry) {
-			return $cacheEntry->getData();
-		} else {
-			return [
-				'name' => basename($path),
-				'mimetype' => FileInfo::MIMETYPE_FOLDER,
-				'mtime' => time(),
-				'storage_mtime' => time(),
-				'etag' => uniqid(),
-				'permissions' => Constants::PERMISSION_ALL,
-				'size' => -1,
-			];
-		}
-	}
-
-	public function versioningEnabled(): bool {
-		if ($this->versioningEnabled === null) {
-			$cached = $this->memCache->get('versioning-enabled::' . $this->getBucket());
-			if ($cached === null) {
-				$this->versioningEnabled = $this->getVersioningStatusFromBucket();
-				$this->memCache->set('versioning-enabled::' . $this->getBucket(), $this->versioningEnabled, 60);
-			} else {
-				$this->versioningEnabled = $cached;
-			}
-		}
-		return $this->versioningEnabled;
-	}
-
-	protected function getVersioningStatusFromBucket(): bool {
-		try {
-			$result = $this->getConnection()->getBucketVersioning(['Bucket' => $this->getBucket()]);
-			return $result->get('Status') === 'Enabled';
-		} catch (S3Exception $s3Exception) {
-			// This is needed for compatibility with Storj gateway which does not support versioning yet
-			if ($s3Exception->getAwsErrorCode() === 'NotImplemented' || $s3Exception->getAwsErrorCode() === 'AccessDenied') {
-				return false;
-			}
-			throw $s3Exception;
-		}
-	}
-
-	public function hasUpdated($path, $time) {
-		// for files we can get the proper mtime
-		if ($path !== '' && $object = $this->headObject($path)) {
-			$stat = $this->objectToMetaData($object);
-			return $stat['mtime'] > $time;
-		} else {
-			// for directories, the only real option we have is to do a prefix listing and iterate over all objects
-			// however, since this is just as expensive as just re-scanning the directory, we can simply return true
-			// and have the scanner figure out if anything has actually changed
-			return true;
-		}
-	}
+    use S3ConnectionTrait;
+    use S3ObjectTrait;
+
+    private LoggerInterface $logger;
+
+    public function needsPartFile() {
+        return false;
+    }
+
+    /** @var CappedMemoryCache<array|false> */
+    private CappedMemoryCache $objectCache;
+
+    /** @var CappedMemoryCache<bool> */
+    private CappedMemoryCache $directoryCache;
+
+    /** @var CappedMemoryCache<array> */
+    private CappedMemoryCache $filesCache;
+
+    private IMimeTypeDetector $mimeDetector;
+    private ?bool $versioningEnabled = null;
+    private ICache $memCache;
+
+    public function __construct($parameters) {
+        parent::__construct($parameters);
+        $this->parseParams($parameters);
+        $this->id = 'amazon::external::' . md5($this->params['hostname'] . ':' . $this->params['bucket'] . ':' . $this->params['key']);
+        $this->objectCache = new CappedMemoryCache();
+        $this->directoryCache = new CappedMemoryCache();
+        $this->filesCache = new CappedMemoryCache();
+        $this->mimeDetector = Server::get(IMimeTypeDetector::class);
+        /** @var ICacheFactory $cacheFactory */
+        $cacheFactory = Server::get(ICacheFactory::class);
+        $this->memCache = $cacheFactory->createLocal('s3-external');
+        $this->logger = Server::get(LoggerInterface::class);
+    }
+
+    /**
+     * @param string $path
+     * @return string correctly encoded path
+     */
+    private function normalizePath($path) {
+        $path = trim($path, '/');
+
+        if (!$path) {
+            $path = '.';
+        }
+
+        return $path;
+    }
+
+    private function isRoot($path) {
+        return $path === '.';
+    }
+
+    private function cleanKey($path) {
+        if ($this->isRoot($path)) {
+            return '/';
+        }
+        return $path;
+    }
+
+    private function clearCache() {
+        $this->objectCache = new CappedMemoryCache();
+        $this->directoryCache = new CappedMemoryCache();
+        $this->filesCache = new CappedMemoryCache();
+    }
+
+    private function invalidateCache($key) {
+        unset($this->objectCache[$key]);
+        $keys = array_keys($this->objectCache->getData());
+        $keyLength = strlen($key);
+        foreach ($keys as $existingKey) {
+            if (substr($existingKey, 0, $keyLength) === $key) {
+                unset($this->objectCache[$existingKey]);
+            }
+        }
+        unset($this->filesCache[$key]);
+        $keys = array_keys($this->directoryCache->getData());
+        $keyLength = strlen($key);
+        foreach ($keys as $existingKey) {
+            if (substr($existingKey, 0, $keyLength) === $key) {
+                unset($this->directoryCache[$existingKey]);
+            }
+        }
+        unset($this->directoryCache[$key]);
+    }
+
+    /**
+     * @return array|false
+     */
+    private function headObject(string $key) {
+        if (!isset($this->objectCache[$key])) {
+            try {
+                $this->objectCache[$key] = $this->getConnection()->headObject([
+                    'Bucket' => $this->bucket,
+                    'Key' => $key
+                ])->toArray();
+            } catch (S3Exception $e) {
+                if ($e->getStatusCode() >= 500) {
+                    throw $e;
+                }
+                $this->objectCache[$key] = false;
+            }
+        }
+
+        if (is_array($this->objectCache[$key]) && !isset($this->objectCache[$key]["Key"])) {
+            /** @psalm-suppress InvalidArgument Psalm doesn't understand nested arrays well */
+            $this->objectCache[$key]["Key"] = $key;
+        }
+        return $this->objectCache[$key];
+    }
+
+    /**
+     * Return true if directory exists
+     *
+     * There are no folders in s3. A folder like structure could be archived
+     * by prefixing files with the folder name.
+     *
+     * Implementation from flysystem-aws-s3-v3:
+     * https://github.com/thephpleague/flysystem-aws-s3-v3/blob/8241e9cc5b28f981e0d24cdaf9867f14c7498ae4/src/AwsS3Adapter.php#L670-L694
+     *
+     * @param $path
+     * @return bool
+     * @throws \Exception
+     */
+    private function doesDirectoryExist($path) {
+        if ($path === '.' || $path === '') {
+            return true;
+        }
+        $path = rtrim($path, '/') . '/';
+
+        if (isset($this->directoryCache[$path])) {
+            return $this->directoryCache[$path];
+        }
+        try {
+            // Maybe this isn't an actual key, but a prefix.
+            // Do a prefix listing of objects to determine.
+            $result = $this->getConnection()->listObjectsV2([
+                'Bucket' => $this->bucket,
+                'Prefix' => $path,
+                'MaxKeys' => 1,
+            ]);
+
+            if (isset($result['Contents'])) {
+                $this->directoryCache[$path] = true;
+                return true;
+            }
+
+            // empty directories have their own object
+            $object = $this->headObject($path);
+
+            if ($object) {
+                $this->directoryCache[$path] = true;
+                return true;
+            }
+        } catch (S3Exception $e) {
+            if ($e->getStatusCode() >= 400 && $e->getStatusCode() < 500) {
+                $this->directoryCache[$path] = false;
+            }
+            throw $e;
+        }
+
+
+        $this->directoryCache[$path] = false;
+        return false;
+    }
+
+    /**
+     * Remove a file or folder
+     *
+     * @param string $path
+     * @return bool
+     */
+    protected function remove($path) {
+        // remember fileType to reduce http calls
+        $fileType = $this->filetype($path);
+        if ($fileType === 'dir') {
+            return $this->rmdir($path);
+        } elseif ($fileType === 'file') {
+            return $this->unlink($path);
+        } else {
+            return false;
+        }
+    }
+
+    public function mkdir($path) {
+        $path = $this->normalizePath($path);
+
+        if ($this->is_dir($path)) {
+            return false;
+        }
+
+        try {
+            $this->getConnection()->putObject([
+                'Bucket' => $this->bucket,
+                'Key' => $path . '/',
+                'Body' => '',
+                'ContentType' => FileInfo::MIMETYPE_FOLDER
+            ]);
+            $this->testTimeout();
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+
+        $this->invalidateCache($path);
+
+        return true;
+    }
+
+    public function file_exists($path) {
+        return $this->filetype($path) !== false;
+    }
+
+
+    public function rmdir($path) {
+        $path = $this->normalizePath($path);
+
+        if ($this->isRoot($path)) {
+            return $this->clearBucket();
+        }
+
+        if (!$this->file_exists($path)) {
+            return false;
+        }
+
+        $this->invalidateCache($path);
+        return $this->batchDelete($path);
+    }
+
+    protected function clearBucket() {
+        $this->clearCache();
+        return $this->batchDelete();
+    }
+
+    private function batchDelete($path = null) {
+        // TODO explore using https://docs.aws.amazon.com/aws-sdk-php/v3/api/class-Aws.S3.BatchDelete.html
+        $params = [
+            'Bucket' => $this->bucket
+        ];
+        if ($path !== null) {
+            $params['Prefix'] = $path . '/';
+        }
+        try {
+            $connection = $this->getConnection();
+            // Since there are no real directories on S3, we need
+            // to delete all objects prefixed with the path.
+            do {
+                // instead of the iterator, manually loop over the list ...
+                $objects = $connection->listObjects($params);
+                // ... so we can delete the files in batches
+                if (isset($objects['Contents'])) {
+                    $connection->deleteObjects([
+                        'Bucket' => $this->bucket,
+                        'Delete' => [
+                            'Objects' => $objects['Contents']
+                        ]
+                    ]);
+                    $this->testTimeout();
+                }
+                // we reached the end when the list is no longer truncated
+            } while ($objects['IsTruncated']);
+            if ($path !== '' && $path !== null) {
+                $this->deleteObject($path);
+            }
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+        return true;
+    }
+
+    public function opendir($path) {
+        try {
+            $content = iterator_to_array($this->getDirectoryContent($path));
+            return IteratorDirectory::wrap(array_map(function (array $item) {
+                return $item['name'];
+            }, $content));
+        } catch (S3Exception $e) {
+            return false;
+        }
+    }
+
+    public function stat($path) {
+        $path = $this->normalizePath($path);
+
+        if ($this->is_dir($path)) {
+            $stat = $this->getDirectoryMetaData($path);
+        } else {
+            $object = $this->headObject($path);
+            if ($object === false) {
+                return false;
+            }
+            $stat = $this->objectToMetaData($object);
+        }
+        $stat['atime'] = time();
+
+        return $stat;
+    }
+
+    /**
+     * Return content length for object
+     *
+     * When the information is already present (e.g. opendir has been called before)
+     * this value is return. Otherwise a headObject is emitted.
+     *
+     * @param $path
+     * @return int|mixed
+     */
+    private function getContentLength($path) {
+        if (isset($this->filesCache[$path])) {
+            return (int)$this->filesCache[$path]['ContentLength'];
+        }
+
+        $result = $this->headObject($path);
+        if (isset($result['ContentLength'])) {
+            return (int)$result['ContentLength'];
+        }
+
+        return 0;
+    }
+
+    /**
+     * Return last modified for object
+     *
+     * When the information is already present (e.g. opendir has been called before)
+     * this value is return. Otherwise a headObject is emitted.
+     *
+     * @param $path
+     * @return mixed|string
+     */
+    private function getLastModified($path) {
+        if (isset($this->filesCache[$path])) {
+            return $this->filesCache[$path]['LastModified'];
+        }
+
+        $result = $this->headObject($path);
+        if (isset($result['LastModified'])) {
+            return $result['LastModified'];
+        }
+
+        return 'now';
+    }
+
+    public function is_dir($path) {
+        $path = $this->normalizePath($path);
+
+        if (isset($this->filesCache[$path])) {
+            return false;
+        }
+
+        try {
+            return $this->doesDirectoryExist($path);
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+    }
+
+    public function filetype($path) {
+        $path = $this->normalizePath($path);
+
+        if ($this->isRoot($path)) {
+            return 'dir';
+        }
+
+        try {
+            if (isset($this->directoryCache[$path]) && $this->directoryCache[$path]) {
+                return 'dir';
+            }
+            if (isset($this->filesCache[$path]) || $this->headObject($path)) {
+                return 'file';
+            }
+            if ($this->doesDirectoryExist($path)) {
+                return 'dir';
+            }
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+
+        return false;
+    }
+
+    public function getPermissions($path) {
+        $type = $this->filetype($path);
+        if (!$type) {
+            return 0;
+        }
+        return $type === 'dir' ? Constants::PERMISSION_ALL : Constants::PERMISSION_ALL - Constants::PERMISSION_CREATE;
+    }
+
+    public function unlink($path) {
+        $path = $this->normalizePath($path);
+
+        if ($this->is_dir($path)) {
+            return $this->rmdir($path);
+        }
+
+        try {
+            $this->deleteObject($path);
+            $this->invalidateCache($path);
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+
+        return true;
+    }
+
+    public function fopen($path, $mode) {
+        $path = $this->normalizePath($path);
+
+        switch ($mode) {
+            case 'r':
+            case 'rb':
+                // Don't try to fetch empty files
+                $stat = $this->stat($path);
+                if (is_array($stat) && isset($stat['size']) && $stat['size'] === 0) {
+                    return fopen('php://memory', $mode);
+                }
+
+                try {
+                    return $this->readObject($path);
+                } catch (S3Exception $e) {
+                    $this->logger->error($e->getMessage(), [
+                        'app' => 'files_external',
+                        'exception' => $e,
+                    ]);
+                    return false;
+                }
+            case 'w':
+            case 'wb':
+                $tmpFile = \OC::$server->getTempManager()->getTemporaryFile();
+
+                $handle = fopen($tmpFile, 'w');
+                return CallbackWrapper::wrap($handle, null, null, function () use ($path, $tmpFile) {
+                    $this->writeBack($tmpFile, $path);
+                });
+            case 'a':
+            case 'ab':
+            case 'r+':
+            case 'w+':
+            case 'wb+':
+            case 'a+':
+            case 'x':
+            case 'x+':
+            case 'c':
+            case 'c+':
+                if (strrpos($path, '.') !== false) {
+                    $ext = substr($path, strrpos($path, '.'));
+                } else {
+                    $ext = '';
+                }
+                $tmpFile = \OC::$server->getTempManager()->getTemporaryFile($ext);
+                if ($this->file_exists($path)) {
+                    $source = $this->readObject($path);
+                    file_put_contents($tmpFile, $source);
+                }
+
+                $handle = fopen($tmpFile, $mode);
+                return CallbackWrapper::wrap($handle, null, null, function () use ($path, $tmpFile) {
+                    $this->writeBack($tmpFile, $path);
+                });
+        }
+        return false;
+    }
+
+    public function touch($path, $mtime = null) {
+        if (is_null($mtime)) {
+            $mtime = time();
+        }
+        $metadata = [
+            'lastmodified' => gmdate(\DateTime::RFC1123, $mtime)
+        ];
+
+        try {
+            if (!$this->file_exists($path)) {
+                $mimeType = $this->mimeDetector->detectPath($path);
+                $this->getConnection()->putObject([
+                    'Bucket' => $this->bucket,
+                    'Key' => $this->cleanKey($path),
+                    'Metadata' => $metadata,
+                    'Body' => '',
+                    'ContentType' => $mimeType,
+                    'MetadataDirective' => 'REPLACE',
+                ]);
+                $this->testTimeout();
+            }
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+
+        $this->invalidateCache($path);
+        return true;
+    }
+
+    public function copy($source, $target, $isFile = null) {
+        $source = $this->normalizePath($source);
+        $target = $this->normalizePath($target);
+
+        if ($isFile === true || $this->is_file($source)) {
+            try {
+                $this->getConnection()->copyObject([
+                    'Bucket' => $this->bucket,
+                    'Key' => $this->cleanKey($target),
+                    'CopySource' => S3Client::encodeKey($this->bucket . '/' . $source)
+                ]);
+                $this->testTimeout();
+            } catch (S3Exception $e) {
+                $this->logger->error($e->getMessage(), [
+                    'app' => 'files_external',
+                    'exception' => $e,
+                ]);
+                return false;
+            }
+        } else {
+            $this->remove($target);
+
+            try {
+                $this->mkdir($target);
+                $this->testTimeout();
+            } catch (S3Exception $e) {
+                $this->logger->error($e->getMessage(), [
+                    'app' => 'files_external',
+                    'exception' => $e,
+                ]);
+                return false;
+            }
+
+            foreach ($this->getDirectoryContent($source) as $item) {
+                $childSource = $source . '/' . $item['name'];
+                $childTarget = $target . '/' . $item['name'];
+                $this->copy($childSource, $childTarget, $item['mimetype'] !== FileInfo::MIMETYPE_FOLDER);
+            }
+        }
+
+        $this->invalidateCache($target);
+
+        return true;
+    }
+
+    public function rename($source, $target) {
+        $source = $this->normalizePath($source);
+        $target = $this->normalizePath($target);
+
+        if ($this->is_file($source)) {
+            if ($this->copy($source, $target) === false) {
+                return false;
+            }
+
+            if ($this->unlink($source) === false) {
+                $this->unlink($target);
+                return false;
+            }
+        } else {
+            if ($this->copy($source, $target) === false) {
+                return false;
+            }
+
+            if ($this->rmdir($source) === false) {
+                $this->rmdir($target);
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    public function test() {
+        $this->getConnection()->headBucket([
+            'Bucket' => $this->bucket
+        ]);
+        return true;
+    }
+
+    public function getId() {
+        return $this->id;
+    }
+
+    public function writeBack($tmpFile, $path) {
+        try {
+            $source = fopen($tmpFile, 'r');
+            $this->writeObject($path, $source, $this->mimeDetector->detectPath($path));
+            $this->invalidateCache($path);
+
+            unlink($tmpFile);
+            return true;
+        } catch (S3Exception $e) {
+            $this->logger->error($e->getMessage(), [
+                'app' => 'files_external',
+                'exception' => $e,
+            ]);
+            return false;
+        }
+    }
+
+    /**
+     * check if curl is installed
+     */
+    public static function checkDependencies() {
+        return true;
+    }
+
+    public function getDirectoryContent($directory): \Traversable {
+        $path = $this->normalizePath($directory);
+
+        if ($this->isRoot($path)) {
+            $path = '';
+        } else {
+            $path .= '/';
+        }
+
+        $results = $this->getConnection()->getPaginator('ListObjectsV2', [
+            'Bucket' => $this->bucket,
+            'Delimiter' => '/',
+            'Prefix' => $path,
+        ]);
+
+        foreach ($results as $result) {
+            // sub folders
+            if (is_array($result['CommonPrefixes'])) {
+                foreach ($result['CommonPrefixes'] as $prefix) {
+                    $dir = $this->getDirectoryMetaData($prefix['Prefix']);
+                    if ($dir) {
+                        yield $dir;
+                    }
+                }
+            }
+            if (is_array($result['Contents'])) {
+                foreach ($result['Contents'] as $object) {
+                    $this->objectCache[$object['Key']] = $object;
+                    if ($object['Key'] !== $path) {
+                        yield $this->objectToMetaData($object);
+                    }
+                }
+            }
+        }
+    }
+
+    private function objectToMetaData(array $object): array {
+        return [
+            'name' => basename($object['Key']),
+            'mimetype' => $this->mimeDetector->detectPath($object['Key']),
+            'mtime' => strtotime($object['LastModified']),
+            'storage_mtime' => strtotime($object['LastModified']),
+            'etag' => $object['ETag'],
+            'permissions' => Constants::PERMISSION_ALL - Constants::PERMISSION_CREATE,
+            'size' => (int)($object['Size'] ?? $object['ContentLength']),
+        ];
+    }
+
+    private function getDirectoryMetaData(string $path): ?array {
+        $path = trim($path, '/');
+        // when versioning is enabled, delete markers are returned as part of CommonPrefixes
+        // resulting in "ghost" folders, verify that each folder actually exists
+        if ($this->versioningEnabled() && !$this->doesDirectoryExist($path)) {
+            return null;
+        }
+        $cacheEntry = $this->getCache()->get($path);
+        if ($cacheEntry instanceof CacheEntry) {
+            return $cacheEntry->getData();
+        } else {
+            return [
+                'name' => basename($path),
+                'mimetype' => FileInfo::MIMETYPE_FOLDER,
+                'mtime' => time(),
+                'storage_mtime' => time(),
+                'etag' => uniqid(),
+                'permissions' => Constants::PERMISSION_ALL,
+                'size' => -1,
+            ];
+        }
+    }
+
+    public function versioningEnabled(): bool {
+        if ($this->versioningEnabled === null) {
+            $cached = $this->memCache->get('versioning-enabled::' . $this->getBucket());
+            if ($cached === null) {
+                $this->versioningEnabled = $this->getVersioningStatusFromBucket();
+                $this->memCache->set('versioning-enabled::' . $this->getBucket(), $this->versioningEnabled, 60);
+            } else {
+                $this->versioningEnabled = $cached;
+            }
+        }
+        return $this->versioningEnabled;
+    }
+
+    protected function getVersioningStatusFromBucket(): bool {
+        try {
+            $result = $this->getConnection()->getBucketVersioning(['Bucket' => $this->getBucket()]);
+            return $result->get('Status') === 'Enabled';
+        } catch (S3Exception $s3Exception) {
+            // This is needed for compatibility with Storj gateway which does not support versioning yet
+            if ($s3Exception->getAwsErrorCode() === 'NotImplemented' || $s3Exception->getAwsErrorCode() === 'AccessDenied') {
+                return false;
+            }
+            throw $s3Exception;
+        }
+    }
+
+    public function hasUpdated($path, $time) {
+        // for files we can get the proper mtime
+        if ($path !== '' && $object = $this->headObject($path)) {
+            $stat = $this->objectToMetaData($object);
+            return $stat['mtime'] > $time;
+        } else {
+            // for directories, the only real option we have is to do a prefix listing and iterate over all objects
+            // however, since this is just as expensive as just re-scanning the directory, we can simply return true
+            // and have the scanner figure out if anything has actually changed
+            return true;
+        }
+    }
 }