#include "async_context_frame.h"

#include "async_wrap-inl.h"

#include "env-inl.h"

#include "node.h"

#include "v8.h"

#include <optional>

namespace node {

using v8::Context;

using v8::Function;

using v8::Global;

using v8::HandleScope;

using v8::Isolate;

using v8::Local;

using v8::MaybeLocal;

using v8::Number;

using v8::Object;

using v8::String;

using v8::Undefined;

using v8::Value;

CallbackScope::CallbackScope(Isolate* isolate,

Local<Object> object,

async_context async_context)

: CallbackScope(Environment::GetCurrent(isolate), object, async_context) {}

CallbackScope::CallbackScope(Environment* env,

Local<Object> object,

async_context asyncContext)

: resource_storage_({.local = object}),

private_(new InternalCallbackScope(

env, &resource_storage_.local, asyncContext)),

try_catch_(env->isolate()) {

try_catch_.SetVerbose(true);

}

CallbackScope::CallbackScope(Environment* env,

Global<Object>* object,

async_context asyncContext)

: resource_storage_({.global_ptr = object}),

private_(new InternalCallbackScope(

env, resource_storage_.global_ptr, asyncContext)),

try_catch_(env->isolate()) {

try_catch_.SetVerbose(true);

// These checks can be removed in a future major version -- they ensure

// ABI compatibility with previous Node.js versions.

static_assert(sizeof(resource_storage_) == sizeof(Global<Object>*));

static_assert(sizeof(resource_storage_) == sizeof(Local<Object>));

static_assert(alignof(decltype(resource_storage_)) ==

alignof(Global<Object>*));

static_assert(alignof(decltype(resource_storage_)) == alignof(Local<Object>));

}

CallbackScope::~CallbackScope() {

if (try_catch_.HasCaught())

private_->MarkAsFailed();

delete private_;

}

InternalCallbackScope::InternalCallbackScope(AsyncWrap* async_wrap, int flags)

: InternalCallbackScope(

async_wrap->env(),

async_wrap->object(),

{async_wrap->get_async_id(), async_wrap->get_trigger_async_id()},

flags,

async_wrap->context_frame()) {}

InternalCallbackScope::InternalCallbackScope(

Environment* env,

std::variant<Local<Object>, Local<Object>*, Global<Object>*> object_arg,

const async_context& asyncContext,

int flags,

Local<Value> context_frame)

: env_(env),

async_context_(asyncContext),

skip_hooks_(flags & kSkipAsyncHooks),

skip_task_queues_(flags & kSkipTaskQueues) {

CHECK_NOT_NULL(env);

std::variant<v8::Local<v8::Object>*, v8::Global<v8::Object>*> object;

if (std::holds_alternative<Local<Object>>(object_arg)) {

object_storage_ = std::get<Local<Object>>(object_arg);

object = &object_storage_;

} else if (std::holds_alternative<Local<Object>*>(object_arg)) {

object = std::get<Local<Object>*>(object_arg);

} else {

object = std::get<Global<Object>*>(object_arg);

}

std::visit([](auto* ptr) { CHECK_NOT_NULL(ptr); }, object);

env->PushAsyncCallbackScope();

if (!env->can_call_into_js()) {

failed_ = true;

return;

}

Isolate* isolate = env->isolate();

if (handle_cleanup_depth > 0) allow_js_.emplace(isolate);

HandleScope handle_scope(isolate);

Local<Context> current_context = isolate->GetCurrentContext();

// If you hit this assertion, the caller forgot to enter the right Node.js

// Environment's v8::Context first.

// We first check `env->context() != current_context` because the contexts

// likely *are* the same, in which case we can skip the slightly more

// expensive Environment::GetCurrent() call.

if (env->context() != current_context) [[unlikely]] {

CHECK_EQ(Environment::GetCurrent(isolate), env);

}

isolate->SetIdle(false);

// The prior frame is usually undefined: no global handle then.

Local<Value> prior_context_frame =

async_context_frame::exchange(env, context_frame);

if (!prior_context_frame->IsUndefined()) {

prior_context_frame_.Reset(isolate, prior_context_frame);

}

env->async_hooks()->push_async_context(

async_context_.async_id, async_context_.trigger_async_id, object);

pushed_ids_ = true;

if (asyncContext.async_id != 0 && !skip_hooks_) {

// No need to check a return value because the application will exit if

// an exception occurs.

AsyncWrap::EmitBefore(env, asyncContext.async_id);

}

}

InternalCallbackScope::~InternalCallbackScope() {

Close();

env_->PopAsyncCallbackScope();

}

void InternalCallbackScope::Close() {

if (closed_) return;

closed_ = true;

// This function must ends up with either cleanup the

// async id stack or pop the topmost one from it

auto perform_stopping_check = [&]() {

if (env_->is_stopping()) {

MarkAsFailed();

env_->async_hooks()->clear_async_id_stack();

}

};

perform_stopping_check();

if (env_->is_stopping()) return;

Isolate* isolate = env_->isolate();

auto idle = OnScopeLeave([&]() { isolate->SetIdle(true); });

if (!failed_ && async_context_.async_id != 0 && !skip_hooks_) {

AsyncWrap::EmitAfter(env_, async_context_.async_id);

}

if (pushed_ids_) {

env_->async_hooks()->pop_async_context(async_context_.async_id);

async_context_frame::set(env_, prior_context_frame_.Get(isolate));

}

if (failed_) return;

if (env_->async_callback_scope_depth() > 1 || skip_task_queues_) {

return;

}

TickInfo* tick_info = env_->tick_info();

if (!env_->can_call_into_js()) return;

auto weakref_cleanup = OnScopeLeave([&]() { env_->RunWeakRefCleanup(); });

Local<Context> context = env_->context();

if (!tick_info->has_tick_scheduled()) {

context->GetMicrotaskQueue()->PerformCheckpoint(isolate);

perform_stopping_check();

}

// Make sure the stack unwound properly. If there are nested MakeCallback's

// then it should return early and not reach this code.

if (env_->async_hooks()->fields()[AsyncHooks::kTotals]) {

CHECK_EQ(env_->execution_async_id(), 0);

CHECK_EQ(env_->trigger_async_id(), 0);

}

if (!tick_info->has_tick_scheduled() && !tick_info->has_rejection_to_warn()) {

return;

}

HandleScope handle_scope(isolate);

Local<Object> process = env_->process_object();

if (!env_->can_call_into_js()) return;

Local<Function> tick_callback = env_->tick_callback_function();

// The tick is triggered before JS land calls SetTickCallback

// to initializes the tick callback during bootstrap.

CHECK(!tick_callback.IsEmpty());

if (tick_callback->Call(context, process, 0, nullptr).IsEmpty()) {

failed_ = true;

}

perform_stopping_check();

}

MaybeLocal<Value> InternalMakeCallback(Environment* env,

Local<Object> resource,

Local<Object> recv,

const Local<Function> callback,

int argc,

Local<Value> argv[],

async_context asyncContext,

Local<Value> context_frame) {

CHECK(!recv.IsEmpty());

#ifdef DEBUG

for (int i = 0; i < argc; i++)

CHECK(!argv[i].IsEmpty());

#endif

Local<Function> hook_cb = env->async_hooks_callback_trampoline();

int flags = InternalCallbackScope::kNoFlags;

bool use_async_hooks_trampoline = false;

AsyncHooks* async_hooks = env->async_hooks();

if (!hook_cb.IsEmpty()) {

// Use the callback trampoline if there are any before or after hooks, or

// we can expect some kind of usage of async_hooks.executionAsyncResource().

flags = InternalCallbackScope::kSkipAsyncHooks;

use_async_hooks_trampoline =

async_hooks->fields()[AsyncHooks::kBefore] +

async_hooks->fields()[AsyncHooks::kAfter] +

async_hooks->fields()[AsyncHooks::kUsesExecutionAsyncResource] > 0;

}

InternalCallbackScope scope(

env, resource, asyncContext, flags, context_frame);

if (scope.Failed()) {

return MaybeLocal<Value>();

}

MaybeLocal<Value> ret;

Local<Context> context = env->context();

if (use_async_hooks_trampoline) {

MaybeStackBuffer<Value, 16> args(env->isolate(), 3 + argc);

args[0] = Number::New(env->isolate(), asyncContext.async_id);

args[1] = resource;

args[2] = callback;

for (int i = 0; i < argc; i++) {

args[i + 3] = argv[i];

}

ret = hook_cb->Call(context, recv, args.length(), &args[0]);

} else {

ret = callback->Call(context, recv, argc, argv);

}

if (ret.IsEmpty()) {

scope.MarkAsFailed();

return MaybeLocal<Value>();

}

scope.Close();

if (scope.Failed()) {

return MaybeLocal<Value>();

}

return ret;

}

// Public MakeCallback()s

MaybeLocal<Value> MakeCallback(Isolate* isolate,

Local<Object> recv,

const char* method,

int argc,

Local<Value> argv[],

async_context asyncContext) {

Local<String> method_string;

if (!String::NewFromUtf8(isolate, method).ToLocal(&method_string)) {

return {};

}

return MakeCallback(isolate, recv, method_string, argc, argv, asyncContext);

}

MaybeLocal<Value> MakeCallback(Isolate* isolate,

Local<Object> recv,

Local<String> symbol,

int argc,

Local<Value> argv[],

async_context asyncContext) {

// Check can_call_into_js() first because calling Get() might do so.

Local<Context> context;

if (!recv->GetCreationContext().ToLocal(&context)) {

return {};

}

Environment* env = Environment::GetCurrent(context);

CHECK_NOT_NULL(env);

if (!env->can_call_into_js()) return {};

Local<Value> callback_v;

if (!recv->Get(isolate->GetCurrentContext(), symbol).ToLocal(&callback_v)) {

return {};

}

if (!callback_v->IsFunction()) {

// This used to return an empty value, but Undefined() makes more sense

// since no exception is pending here.

return Undefined(isolate);

}

Local<Function> callback = callback_v.As<Function>();

return MakeCallback(isolate, recv, callback, argc, argv, asyncContext);

}

MaybeLocal<Value> MakeCallback(Isolate* isolate,

Local<Object> recv,

Local<Function> callback,

int argc,

Local<Value> argv[],

async_context asyncContext) {

return InternalMakeCallback(

isolate, recv, callback, argc, argv, asyncContext, Undefined(isolate));

}

MaybeLocal<Value> InternalMakeCallback(Isolate* isolate,

Local<Object> recv,

Local<Function> callback,

int argc,

Local<Value> argv[],

async_context asyncContext,

Local<Value> context_frame) {

// Observe the following two subtleties:

//

// 1. The environment is retrieved from the callback function's context.

// 2. The context to enter is retrieved from the environment.

//

// Because of the AssignToContext() call in src/node_contextify.cc,

// the two contexts need not be the same.

Local<Context> context;

if (!callback->GetCreationContext().ToLocal(&context)) {

return {};

}

Environment* env = Environment::GetCurrent(context);

CHECK_NOT_NULL(env);

// Entering the context changes nothing when it is already the entered and

// the current one, which is the common case for addons.

Local<Context> env_context = env->context();

std::optional<Context::Scope> context_scope;

if (isolate->GetEnteredOrMicrotaskContext() != env_context ||

isolate->GetCurrentContext() != env_context) {

context_scope.emplace(env_context);

}

MaybeLocal<Value> ret = InternalMakeCallback(

env, recv, recv, callback, argc, argv, asyncContext, context_frame);

if (ret.IsEmpty() && env->async_callback_scope_depth() == 0) {

// This is only for legacy compatibility and we may want to look into

// removing/adjusting it.

return Undefined(isolate);

}

return ret;

}

// Use this if you just want to safely invoke some JS callback and

// would like to retain the currently active async_context, if any.

// In case none is available, a fixed default context will be

// installed otherwise.

MaybeLocal<Value> MakeSyncCallback(Isolate* isolate,

Local<Object> recv,

Local<Function> callback,

int argc,

Local<Value> argv[]) {

Local<Context> context;

if (!callback->GetCreationContext().ToLocal(&context)) {

return {};

}

Environment* env = Environment::GetCurrent(context);

CHECK_NOT_NULL(env);

if (!env->can_call_into_js()) return {};

Context::Scope context_scope(context);

if (env->async_callback_scope_depth()) {

// There's another MakeCallback() on the stack, piggy back on it.

// In particular, retain the current async_context.

return callback->Call(context, recv, argc, argv);

}

// This is a toplevel invocation and the caller (intentionally)

// didn't provide any async_context to run in. Install a default context.

MaybeLocal<Value> ret = InternalMakeCallback(env,

env->process_object(),

recv,

callback,

argc,

argv,

async_context{0, 0},

Undefined(isolate));

return ret;

}

} // namespace node