s3: fix delete of directory marker on non-empty directory (#8731)

When deleting an S3 key ending with "/" (a directory marker) where the
directory has children, strip the marker metadata instead of returning
InternalError. This matches AWS S3 behavior where deleting a directory
marker only removes that object, not child objects under the prefix.

weed/s3api/filer_util.go

@@ -78,6 +78,43 @@ func doDeleteEntry(client filer_pb.SeaweedFilerClient, parentDirectoryPath strin
 	return nil
 }
 
+// removeDirectoryKeyObjectMarker clears the MIME type and S3-specific metadata from a
+// directory entry so it no longer appears as an object in S3 listings (IsDirectoryKeyObject()
+// returns false). This handles the case where a directory marker (key ending with "/") is
+// deleted on a non-empty directory — matching AWS S3 behavior where deleting the marker
+// only removes that object, not the child objects under the prefix.
+func removeDirectoryKeyObjectMarker(client filer_pb.SeaweedFilerClient, parentDir, entryName string) error {
+	ctx := context.Background()
+	resp, err := filer_pb.LookupEntry(ctx, client, &filer_pb.LookupDirectoryEntryRequest{
+		Directory: parentDir,
+		Name:      entryName,
+	})
+	if err != nil {
+		if errors.Is(err, filer_pb.ErrNotFound) {
+			return nil
+		}
+		return err
+	}
+	entry := resp.Entry
+	if entry == nil || !entry.IsDirectory || entry.Attributes == nil || entry.Attributes.Mime == "" {
+		return nil // Not a directory key object, nothing to remove
+	}
+
+	// Clear marker metadata so IsDirectoryKeyObject() returns false
+	entry.Attributes.Mime = ""
+	entry.Attributes.Md5 = nil
+	entry.Content = nil
+	if entry.Extended != nil {
+		delete(entry.Extended, s3_constants.ExtETagKey)
+		delete(entry.Extended, s3_constants.ExtAmzOwnerKey)
+	}
+
+	return filer_pb.UpdateEntry(ctx, client, &filer_pb.UpdateEntryRequest{
+		Directory: parentDir,
+		Entry:     entry,
+	})
+}
+
 func (s3a *S3ApiServer) exists(parentDirectoryPath string, entryName string, isDirectory bool) (exists bool, err error) {
 
 	return filer_pb.Exists(context.Background(), s3a, parentDirectoryPath, entryName, isDirectory)

weed/s3api/s3api_object_handlers_delete.go

@@ -130,7 +130,15 @@ func (s3a *S3ApiServer) DeleteObjectHandler(w http.ResponseWriter, r *http.Reque
 		dir, name := target.DirAndName()
 
 		err := s3a.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
-			return doDeleteEntry(client, dir, name, true, false)
+			deleteErr := doDeleteEntry(client, dir, name, true, false)
+			if deleteErr != nil && strings.HasSuffix(object, "/") &&
+				strings.Contains(deleteErr.Error(), filer.MsgFailDelNonEmptyFolder) {
+				// Deleting a directory key object (S3 key ending with "/") on a non-empty
+				// directory. Strip the marker metadata so it no longer appears as an S3 object,
+				// matching AWS S3 behavior where only the marker is removed, not child objects.
+				return removeDirectoryKeyObjectMarker(client, dir, name)
+			}
+			return deleteErr
 			// Note: Empty folder cleanup is now handled asynchronously by EmptyFolderCleaner
 			// which listens to metadata events and uses consistent hashing for coordination
 		})
@@ -349,6 +357,11 @@ func (s3a *S3ApiServer) DeleteMultipleObjectsHandler(w http.ResponseWriter, r *h
 				if err == nil {
 					deletedObjects = append(deletedObjects, object)
 				} else if strings.Contains(err.Error(), filer.MsgFailDelNonEmptyFolder) {
+					if strings.HasSuffix(object.Key, "/") {
+						if markerErr := removeDirectoryKeyObjectMarker(client, parentDirectoryPath, entryName); markerErr != nil {
+							glog.Warningf("DeleteMultipleObjectsHandler: failed to remove directory marker %s/%s: %v", parentDirectoryPath, entryName, markerErr)
+						}
+					}
 					deletedObjects = append(deletedObjects, object)
 				} else {
 					deleteErrors = append(deleteErrors, DeleteError{