worker: enable passing command line flags

This PR adds the ability to provide Workers with their own
execArgv flags in replacement of the main thread's execArgv. Only
per-Isolate/per-Environment options are allowed. Per-Process options
and V8 flags are not allowed. Passing an empty execArgv array will
reset per-Isolate and per-Environment options of the Worker to their
defaults. If execArgv option is not passed, the Worker will get
the same flags as the main thread.

Usage example:
```
const worker = new Worker(__filename, {
    execArgv: ['--trace-warnings'],
});
```

PR-URL: https://github.com/nodejs/node/pull/25467
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

1 files changed, 64 insertions, 3 deletions

diff --git a/src/node_worker.cc b/src/node_worker.cc
index dab7945aae..30004957a4 100644
--- a/src/node_worker.cc
+++ b/src/node_worker.cc
@@ -10,7 +10,9 @@
 #include "async_wrap-inl.h"
 
 #include <string>
+#include <vector>
 
+using node::options_parser::kDisallowedInEnvironment;
 using v8::ArrayBuffer;
 using v8::Context;
 using v8::Function;
@@ -68,7 +70,10 @@ void WaitForWorkerInspectorToStop(Environment* child) {}
 
 }  // anonymous namespace
 
-Worker::Worker(Environment* env, Local<Object> wrap, const std::string& url)
+Worker::Worker(Environment* env,
+               Local<Object> wrap,
+               const std::string& url,
+               std::shared_ptr<PerIsolateOptions> per_isolate_opts)
     : AsyncWrap(env, wrap, AsyncWrap::PROVIDER_WORKER), url_(url) {
   // Generate a new thread id.
   {
@@ -113,6 +118,9 @@ Worker::Worker(Environment* env, Local<Object> wrap, const std::string& url)
                                           &loop_,
                                           env->isolate_data()->platform(),
                                           array_buffer_allocator_.get()));
+    if (per_isolate_opts != nullptr) {
+      isolate_data_->set_options(per_isolate_opts);
+    }
     CHECK(isolate_data_);
 
     Local<Context> context = NewContext(isolate_);
@@ -391,14 +399,67 @@ void Worker::New(const FunctionCallbackInfo<Value>& args) {
   }
 
   std::string url;
+  std::shared_ptr<PerIsolateOptions> per_isolate_opts = nullptr;
+
   // Argument might be a string or URL
-  if (args.Length() == 1 && !args[0]->IsNullOrUndefined()) {
+  if (args.Length() > 0 && !args[0]->IsNullOrUndefined()) {
     Utf8Value value(
         args.GetIsolate(),
         args[0]->ToString(env->context()).FromMaybe(v8::Local<v8::String>()));
     url.append(value.out(), value.length());
+
+    if (args.Length() > 1 && args[1]->IsArray()) {
+      v8::Local<v8::Array> array = args[1].As<v8::Array>();
+      // The first argument is reserved for program name, but we don't need it
+      // in workers.
+      std::vector<std::string> exec_argv = {""};
+      uint32_t length = array->Length();
+      for (uint32_t i = 0; i < length; i++) {
+        v8::Local<v8::Value> arg;
+        if (!array->Get(env->context(), i).ToLocal(&arg)) {
+          return;
+        }
+        v8::MaybeLocal<v8::String> arg_v8_string =
+            arg->ToString(env->context());
+        if (arg_v8_string.IsEmpty()) {
+          return;
+        }
+        Utf8Value arg_utf8_value(
+            args.GetIsolate(),
+            arg_v8_string.FromMaybe(v8::Local<v8::String>()));
+        std::string arg_string(arg_utf8_value.out(), arg_utf8_value.length());
+        exec_argv.push_back(arg_string);
+      }
+
+      std::vector<std::string> invalid_args{};
+      std::vector<std::string> errors{};
+      per_isolate_opts.reset(new PerIsolateOptions());
+
+      // Using invalid_args as the v8_args argument as it stores unknown
+      // options for the per isolate parser.
+      options_parser::PerIsolateOptionsParser::instance.Parse(
+          &exec_argv,
+          nullptr,
+          &invalid_args,
+          per_isolate_opts.get(),
+          kDisallowedInEnvironment,
+          &errors);
+
+      // The first argument is program name.
+      invalid_args.erase(invalid_args.begin());
+      if (errors.size() > 0 || invalid_args.size() > 0) {
+        v8::Local<v8::Value> value =
+            ToV8Value(env->context(),
+                      errors.size() > 0 ? errors : invalid_args)
+                .ToLocalChecked();
+        Local<String> key =
+            FIXED_ONE_BYTE_STRING(env->isolate(), "invalidExecArgv");
+        args.This()->Set(env->context(), key, value).FromJust();
+        return;
+      }
+    }
   }
-  new Worker(env, args.This(), url);
+  new Worker(env, args.This(), url, per_isolate_opts);
 }
 
 void Worker::StartThread(const FunctionCallbackInfo<Value>& args) {