src: allow preventing debug signal handler start

PR-URL: #46681
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>

src/env-inl.h

@@ -677,6 +677,10 @@ inline bool Environment::no_global_search_paths() const {
          !options_->global_search_paths;
 }
 
+inline bool Environment::should_start_debug_signal_handler() const {
+  return (flags_ & EnvironmentFlags::kNoStartDebugSignalHandler) == 0;
+}
+
 inline bool Environment::no_browser_globals() const {
   // configure --no-browser-globals
 #ifdef NODE_NO_BROWSER_GLOBALS

src/env.h

@@ -801,6 +801,7 @@ class Environment : public MemoryRetainer {
   inline bool tracks_unmanaged_fds() const;
   inline bool hide_console_windows() const;
   inline bool no_global_search_paths() const;
+  inline bool should_start_debug_signal_handler() const;
   inline bool no_browser_globals() const;
   inline uint64_t thread_id() const;
   inline worker::Worker* worker_context() const;

src/inspector_agent.cc

@@ -717,8 +717,11 @@ bool Agent::Start(const std::string& path,
                               StartIoThreadAsyncCallback));
     uv_unref(reinterpret_cast<uv_handle_t*>(&start_io_thread_async));
     start_io_thread_async.data = this;
-    // Ignore failure, SIGUSR1 won't work, but that should not block node start.
-    StartDebugSignalHandler();
+    if (parent_env_->should_start_debug_signal_handler()) {
+      // Ignore failure, SIGUSR1 won't work, but that should not block node
+      // start.
+      StartDebugSignalHandler();
+    }
 
     parent_env_->AddCleanupHook([](void* data) {
       Environment* env = static_cast<Environment*>(data);

src/node.h

@@ -657,7 +657,11 @@ enum Flags : uint64_t {
   // This control is needed by embedders who may not want to initialize the V8
   // inspector in situations where one has already been created,
   // e.g. Blink's in Chromium.
-  kNoCreateInspector = 1 << 9
+  kNoCreateInspector = 1 << 9,
+  // Controls where or not the InspectorAgent for this Environment should
+  // call StartDebugSignalHandler.  This control is needed by embedders who may
+  // not want to allow other processes to start the V8 inspector.
+  kNoStartDebugSignalHandler = 1 << 10
 };
 }  // namespace EnvironmentFlags