writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	// Check if anonymous (non-owner) has access to list objects.
	readable := globalPolicySys.IsAllowed(policy.BucketPolicyArgs{
		Action:          policy.ListBucketAction,
		BucketName:      bucket,
		ConditionValues: getConditionValues(r, "", auth.AnonymousCredentials),