Add scripting capability to your C++ project using Windows Script Host

ws-scripting.cpp

#include <windows.h>
#include <objbase.h>
#include <activscp.h>
#include <atomic>
#include <cassert>
#include <cstdio>

class ScriptSite : public IActiveScriptSite
{
public:

  HRESULT QueryInterface(REFIID interface_id, void **object) override
  {
    if (object == nullptr)
    {
      return E_POINTER;
    }

    if (interface_id == IID_IUnknown || interface_id == IID_IActiveScript)
    {
      *object = this;
      AddRef();
      return S_OK;
    }

    return E_NOINTERFACE;
  }

  ULONG AddRef() override
  {
    return ++reference_counter;
  }

  ULONG Release() override
  {
    if (--reference_counter == 0)
    {
      delete this;
      return 0;
    }

    return reference_counter;
  }

  HRESULT STDMETHODCALLTYPE GetLCID(LCID *local_id) override
  {
    (void)local_id;

    return E_NOTIMPL;
  }

  HRESULT STDMETHODCALLTYPE GetItemInfo(LPCOLESTR item_name,
                                        DWORD return_mask,
                                        IUnknown **item,
                                        ITypeInfo **type_info) override
  {
    (void)item_name;
    (void)return_mask;
    (void)item;
    (void)type_info;

    return TYPE_E_ELEMENTNOTFOUND;
  }

  HRESULT STDMETHODCALLTYPE GetDocVersionString(BSTR *document_version) override
  {
    (void)document_version;

    return S_OK;
  }

  HRESULT STDMETHODCALLTYPE OnScriptTerminate(const VARIANT *result, const EXCEPINFO *exception_information) override
  {
    (void)result;
    (void)exception_information;

    return S_OK;
  }

  HRESULT STDMETHODCALLTYPE OnStateChange(SCRIPTSTATE script_state) override
  {
    (void)script_state;

    return S_OK;
  }

  HRESULT STDMETHODCALLTYPE OnScriptError(IActiveScriptError *script_error) override
  {
    (void)script_error;

    return S_OK;
  }

  HRESULT STDMETHODCALLTYPE OnEnterScript() override
  {
    return S_OK;
  }

  HRESULT STDMETHODCALLTYPE OnLeaveScript() override
  {
    return S_OK;
  }

private:

  virtual ~ScriptSite() = default;

  std::atomic<DWORD> reference_counter {1};
};

int main()
{
  HRESULT hr;

  hr = CoInitializeEx(nullptr, COINIT_MULTITHREADED);
  assert(SUCCEEDED(hr));

  CLSID script_class_id;
  hr = CLSIDFromProgID(L"JScript", &script_class_id);
  assert(SUCCEEDED(hr));

  IActiveScript *active_script;
  hr = CoCreateInstance(script_class_id, nullptr, CLSCTX_SERVER, IID_IActiveScript, reinterpret_cast<void **>(&active_script));
  assert(SUCCEEDED(hr));

  IActiveScriptSite *active_script_site = new ScriptSite;
  hr = active_script->SetScriptSite(active_script_site);
  assert(SUCCEEDED(hr));
  active_script_site->Release();

  // uuid.lib on MinGW does not export IID_IActiveScriptParse* class IDs
#if 1
  const GUID IID_IActiveScriptParse64_MingwFix {0xc7ef7658, 0xe1ee, 0x480e, {0x97, 0xea, 0xd5, 0x2c, 0xb4, 0xd7, 0x6d, 0x17}};
#elif 0
  const GUID IID_IActiveScriptParse32_MingwFix {0xbb1a2ae2, 0xa4f9, 0x11cf, {0x8f, 0x20, 0x00, 0x80, 0x5f, 0x2c, 0xd0, 0x64}};
#endif

  IActiveScriptParse *active_script_parse;
  hr = active_script->QueryInterface(IID_IActiveScriptParse64_MingwFix, reinterpret_cast<void **>(&active_script_parse));
  assert(SUCCEEDED(hr));

  hr = active_script_parse->InitNew();
  assert(SUCCEEDED(hr));

  VARIANT result;
  VariantInit(&result);

  EXCEPINFO exception_information;
  hr = active_script_parse->ParseScriptText(L"(function() { (new ActiveXObject('WScript.Shell')).Run('calc.exe'); return 1337; })()",
                                            nullptr,
                                            nullptr,
                                            nullptr,
                                            0,
                                            0,
                                            SCRIPTTEXT_ISEXPRESSION,
                                            &result,
                                            &exception_information);
  assert(SUCCEEDED(hr));

  assert(V_VT(&result) == VT_I4);
  std::printf("%ld\n", V_I4(&result));

  VariantClear(&result);

  active_script_parse->Release();

  active_script->Release();

  CoUninitialize();
}