core: error: add function to test if an error has a particular vendor/code

core/error.c

@@ -38,6 +38,20 @@ static void error_cleanup(void)
 	}
 }
 
+bool b_result_is(
+	struct b_error *err, const b_error_vendor *vendor, b_error_status_code code)
+{
+	if (!err) {
+		return false;
+	}
+
+	if (err->err_vendor != vendor) {
+		return false;
+	}
+
+	return err->err_code == code;
+}
+
 const struct b_error_vendor *b_error_vendor_get_builtin(void)
 {
 	return &builtin_vendor;