fix: harden object store against copying a file to itself

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

Author: icewind1991

lib/private/Files/ObjectStore/ObjectStoreStorage.php

@@ -723,6 +723,18 @@ private function copyFile(ICache $sourceCache, ICacheEntry $sourceEntry, string
 
 		$targetId = $cache->copyFromCache($sourceCache, $sourceEntry, $to);
 
+		if ($targetId === $sourceEntry->getId()) {
+			// copying a file to itself? No need to do anything
+			$e = new \Exception('Object ' . $sourceEntry->getPath() . ' (' . $sourceEntry->getId() . ') being copied to itself');
+			if ($sourceEntry instanceof CacheEntry) {
+				$sourceData = $sourceEntry->getData();
+			} else {
+				$sourceData = null;
+			}
+			$this->logger->warning($e->getMessage(), ['exception' => $e, 'source' => $sourceData]);
+			return;
+		}
+
 		$targetUrn = $this->getURN($targetId);
 
 		try {