From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Samuel Attard <samuel.r.attard@gmail.com>
Date: Mon, 7 Mar 2022 16:36:28 -0800
Subject: feat: add kNoStartDebugSignalHandler to Environment to prevent
 SIGUSR1 handling

This patch should be upstreamed, it allows embedders to prevent the call to StartDebugSignalHandler which handles SIGUSR1 and starts the inspector agent.  Apps that have --inspect disabled also don't want SIGUSR1 to have this affect.

diff --git a/src/env-inl.h b/src/env-inl.h
index 793dc72e0dbad819a1c3a51521b4a39b76c7015d..222c78ef0cb9904742fd44f8182278ab1f50cd59 100644
--- a/src/env-inl.h
+++ b/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
diff --git a/src/env.h b/src/env.h
index afe67d2237ae6933de44dd1141cf388e9a48cee3..87df6e1f32e584aa0c6ae21856299fff31d67669 100644
--- a/src/env.h
+++ b/src/env.h
@@ -787,6 +787,7 @@ 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;
diff --git a/src/inspector_agent.cc b/src/inspector_agent.cc
index f0b4cc43c864aee1fab8e073ea110ea108c653ab..6d12e27b955fb9fddab24d846e563c969bb48ae7 100644
--- a/src/inspector_agent.cc
+++ b/src/inspector_agent.cc
@@ -707,8 +707,10 @@ 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);
diff --git a/src/node.h b/src/node.h
index dcce529664e1d126115545d6ba7f5b8492b0e921..99d2e1384df4000d4e1f1ffeafa83d29a152054b 100644
--- a/src/node.h
+++ b/src/node.h
@@ -654,7 +654,11 @@ 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