src: use uint32_t for process initialization flags enum

Refs: #45221
PR-URL: #46427
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

src/node.cc

@@ -431,7 +431,13 @@ void ResetSignalHandlers() {
 #endif  // __POSIX__
 }
 
+// We use uint32_t since that can be accessed as a lock-free atomic
+// variable on all platforms that we support, which we require in
+// order for its value to be usable inside signal handlers.
 static std::atomic<uint32_t> init_process_flags = 0;
+static_assert(
+    std::is_same_v<std::underlying_type_t<ProcessInitializationFlags::Flags>,
+                   uint32_t>);
 
 static void PlatformInit(ProcessInitializationFlags::Flags flags) {
   // init_process_flags is accessed in ResetStdio(),
@@ -1057,7 +1063,7 @@ std::unique_ptr<InitializationResult> InitializeOncePerProcess(
 }
 
 void TearDownOncePerProcess() {
-  const uint64_t flags = init_process_flags.load();
+  const uint32_t flags = init_process_flags.load();
   ResetStdio();
   if (!(flags & ProcessInitializationFlags::kNoDefaultSignalHandling)) {
     ResetSignalHandlers();

src/node.h

@@ -227,10 +227,8 @@ class Environment;
 class MultiIsolatePlatform;
 class InitializationResultImpl;
 
-namespace ProcessFlags {
-// TODO(addaleax): Switch to uint32_t to match std::atomic<uint32_t>
-// init_process_flags in node.cc
-enum Flags : uint64_t {
+namespace ProcessInitializationFlags {
+enum Flags : uint32_t {
   kNoFlags = 0,
   // Enable stdio inheritance, which is disabled by default.
   // This flag is also implied by kNoStdioInitialization.
@@ -270,9 +268,8 @@ enum Flags : uint64_t {
       kNoParseGlobalDebugVariables | kNoAdjustResourceLimits |
       kNoUseLargePages | kNoPrintHelpOrVersionOutput,
 };
-}  // namespace ProcessFlags
-// TODO(addaleax): Make this the canonical name, as it is more descriptive.
-namespace ProcessInitializationFlags = ProcessFlags;
+}  // namespace ProcessInitializationFlags
+namespace ProcessFlags = ProcessInitializationFlags;  // Legacy alias.
 
 class NODE_EXTERN InitializationResult {
  public: