bootstrap: move event loop handle checking into snapshot builder

This is only necessary for the snapshot builder (because we have no way to resurrect the handles at the moment). In addition, print the handles if the debug flag is set or if the queues are not empty after snapshot is created. PR-URL: #39007 Refs: #35711 Refs: #38905 Reviewed-By: James M Snell <[email protected]> Reviewed-By: Colin Ihrig <[email protected]>

Author: joyeecheung

src/node_main_instance.cc

@@ -224,8 +224,6 @@ NodeMainInstance::CreateMainEnvironment(int* exit_code,
  }
  }
 
-CHECK(env->req_wrap_queue()->IsEmpty());
-CHECK(env->handle_wrap_queue()->IsEmpty());
 return env;
 }
 

src/node_snapshotable.cc

@@ -157,7 +157,22 @@ void SnapshotBuilder::Generate(SnapshotData* out,
 // Must be out of HandleScope
  out->blob =
  creator.CreateBlob(SnapshotCreator::FunctionCodeHandling::kClear);
+
+// We must be able to rehash the blob when we restore it or otherwise
+// the hash seed would be fixed by V8, introducing a vulnerability.
 CHECK(out->blob.CanBeRehashed());
+
+// We cannot resurrect the handles from the snapshot, so make sure that
+// no handles are left open in the environment after the blob is created
+// (which should trigger a GC and close all handles that can be closed).
+if (!env->req_wrap_queue()->IsEmpty()
+ || !env->handle_wrap_queue()->IsEmpty()
+ || per_process::enabled_debug_list.enabled(DebugCategory::MKSNAPSHOT)){
+PrintLibuvHandleInformation(env->event_loop(), stderr);
+ }
+CHECK(env->req_wrap_queue()->IsEmpty());
+CHECK(env->handle_wrap_queue()->IsEmpty());
+
 // Must be done while the snapshot creator isolate is entered i.e. the
 // creator is still alive.
 FreeEnvironment(env);