[wasm] Initial signal handler

src/trap-handler/trap-handler-internal.h

+// Copyright 2016 the V8 project 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 TRAP_HANDLER_INTERNAL_H_
+#define TRAP_HANDLER_INTERNAL_H_
+
+// This file should not be included (even transitively) by files outside of
+// src/trap-handler.
+
+#include "src/trap-handler/trap-handler.h"
+
+#include <atomic>
+
+namespace v8 {
+namespace internal {
+namespace trap_handler {
+
+bool MaybeHandleFault(int signum, void* siginfo, void* context);
+
+struct CodeObjectData {
+  void* base;
+  size_t size;
+  size_t num_protected_instructions;
+  // TODO(eholk): this is C++, and flexible array members are
+  // apparently not allowed.
+  ProtectedInstructionData instructions[];
+};
+
+class MetadataLock {
+  static std::atomic_flag spinlock_;
+
+ public:
+  MetadataLock();
+
+  ~MetadataLock();
+};
+
+}  // namespace trap_handler
+}  // namespace internal
+}  // namespace v8
+
+#endif  // TRAP_HANDLER_INTERNAL_H_