如何停止从 wee8 中导入的主机函数执行嵌入式代码？

Question

wee8（v8 的 wasm api）是否有办法停止从导入的宿主函数中执行嵌入式访客函数？

示例：

auto hostFunc(const wasm::Val args[], wasm::Val results[]) -> wasm::own<wasm::Trap> {
    std::cout << "host called!" << std::endl;
    if (<some condition>) {
        // Stop the execution of the guest code, return control to host.
    }
    return nullptr;
}

嵌入代码取自 v8 的示例，减去一些检查和打印（以缩短代码段）。

void embedWasmCode(wasm::vec<byte_t> binary) {
    auto store_ = wasm::Store::make(engine.get());
    auto store = store_.get();
    auto module = wasm::Module::make(store, binary);
    auto func_type = wasm::FuncType::make(
            wasm::ownvec<wasm::ValType>::make(),
            wasm::ownvec<wasm::ValType>::make()
    );
    auto callback = wasm::Func::make(store, func_type.get(), hostFunc);
    wasm::Extern* imports[] = {callback.get()};
    auto instance = wasm::Instance::make(store, module.get(), imports);
    auto exports = instance->exports();
    auto run_func = exports[0]->func();
    auto res = run_func->call();
    // When the execution of run_func gets to the host function, the host function
    // stops run_func's execution if some condition is met and execution returns 
    // to the host, here.

    // ... more code
}

例如，Wasmer 具有记录在案的此功能 here。

Answer 1

是有办法的，当然可以在示例中找到。

来自trap.cc：

auto fail_callback(
  void* env, const wasm::Val args[], wasm::Val results[]
) -> wasm::own<wasm::Trap> {
  std::cout << "Calling back..." << std::endl;
  auto store = reinterpret_cast<wasm::Store*>(env);
  auto message = wasm::Name::make(std::string("callback abort"));
  return wasm::Trap::make(store, message);
}

通过 return 从主机函数中获取陷阱对象，来宾代码（调用导入的主机函数）的执行将停止，控制权将 return 交给主机。

如何停止从 wee8 中导入的主机函数执行嵌入式代码？

How to stop embedded code execution from imported host function in wee8?

v8

webassembly