1 files changed, 52 insertions, 0 deletions
diff --git a/dom/quota/AssertionsImpl.h b/dom/quota/AssertionsImpl.h
new file mode 100644
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+++ b/dom/quota/AssertionsImpl.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef DOM_QUOTA_ASSERTIONSIMPL_H_
+#define DOM_QUOTA_ASSERTIONSIMPL_H_
+
+#include "mozilla/dom/quota/Assertions.h"
+
+#include <type_traits>
+#include "mozilla/Assertions.h"
+
+namespace mozilla::dom::quota {
+
+namespace detail {
+
+template <typename T, bool = std::is_unsigned_v<T>>
+struct IntChecker {
+  static void Assert(T aInt) {
+    static_assert(std::is_integral_v<T>, "Not an integer!");
+    MOZ_ASSERT(aInt >= 0);
+  }
+};
+
+template <typename T>
+struct IntChecker<T, true> {
+  static void Assert(T aInt) {
+    static_assert(std::is_integral_v<T>, "Not an integer!");
+  }
+};
+
+}  // namespace detail
+
+template <typename T>
+void AssertNoOverflow(uint64_t aDest, T aArg) {
+  detail::IntChecker<T>::Assert(aDest);
+  detail::IntChecker<T>::Assert(aArg);
+  MOZ_ASSERT(UINT64_MAX - aDest >= uint64_t(aArg));
+}
+
+template <typename T, typename U>
+void AssertNoUnderflow(T aDest, U aArg) {
+  detail::IntChecker<T>::Assert(aDest);
+  detail::IntChecker<T>::Assert(aArg);
+  MOZ_ASSERT(uint64_t(aDest) >= uint64_t(aArg));
+}
+
+}  // namespace mozilla::dom::quota
+
+#endif  // DOM_QUOTA_ASSERTIONSIMPL_H_