Merge pull request #59828 from nextcloud/backport/59597/stable32

[stable32] fix(s3): ignore prefixes with repeating delimiters

Author: leftybournes

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

@@ -645,6 +645,12 @@ public function getDirectoryContent(string $directory): \Traversable {
 			// sub folders
 			if (is_array($result['CommonPrefixes'])) {
 				foreach ($result['CommonPrefixes'] as $prefix) {
+					if (preg_match('/\/{2,}$/', $prefix['Prefix'])) {
+						$this->logger->warning('Detected a repeating delimiter in prefix \'' . $prefix['Prefix']
+											   . '\'. This is unsupported and its contents have been ignored.');
+						continue;
+					}
+
 					$dir = $this->getDirectoryMetaData($prefix['Prefix']);
 					if ($dir) {
 						yield $dir;