Check C API structure sizes before copying values to C++ classes (fixes issue #3238)

libcef_dll/template_util.h

@@ -0,0 +1,37 @@
+// Copyright (c) 2022 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+#ifndef CEF_LIBCEF_DLL_TEMPLATE_UTIL_H_
+#define CEF_LIBCEF_DLL_TEMPLATE_UTIL_H_
+#pragma once
+
+#include <type_traits>
+
+namespace template_util {
+
+// Used to detect whether the given C struct has a size_t size field or has a
+// base field and a base field has a size field.
+template <typename T, typename = void>
+struct HasValidSize {
+  bool operator()(const T*) { return true; }
+};
+template <typename T>
+struct HasValidSize<
+    T,
+    typename std::enable_if_t<std::is_same<decltype(T::size), size_t>::value>> {
+  bool operator()(const T* s) { return s->size == sizeof(*s); }
+};
+template <typename T>
+struct HasValidSize<T, decltype(void(T::base.size))> {
+  bool operator()(const T* s) { return s->base.size == sizeof(*s); }
+};
+
+template <typename T>
+inline bool has_valid_size(const T* s) {
+  return HasValidSize<T>()(s);
+}
+
+}  // namespace template_util
+
+#endif  // CEF_LIBCEF_DLL_TEMPLATE_UTIL_H_