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fix unhandled exception (empty arguments and uninitialized m_pEI) #29

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Merged
tablacus merged 2 commits into from
Sep 7, 2022
Merged

fix unhandled exception (empty arguments and uninitialized m_pEI) #29

tablacus merged 2 commits into from
Sep 7, 2022

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@ghuDaYuYu
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@ghuDaYuYu ghuDaYuYu commented Sep 6, 2022 •
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First of all thank you so much for providing this library!
I pull this request to share fixes that seam to have solved two issues I encountered.

  • Crash on syntax error:

app. c++

IScriptControlPtr script_control;
_com_util::CheckError(script_control.CreateInstance(__uuidof(ScriptControl)));

try {

	BSTR bsLang = ::SysAllocString(L"JScript");
	script_control->put_Language(bsLang);
	::SysFreeString(bsLang);

	BSTR bsScript = ::SysAllocString(L"function badSyntax() return new Array(0, 1, 2);}");
	script_control->AddCode(bsScript);
	::SysFreeString(bsScript);

} catch (_com_error& e) {

      ::SysFreeString(bsScript);
      rethrow_error(e);
}

The missing bracket in the script triggered either an unhandled exception in jscript.dll or AV exceptions.

Initializing m_pEI inside the CTScriptControl constructor seams to solve it:

CTScriptControl::CTScriptControl()
{
	ITypeLib *pTypeLib;
	m_pEI = NULL;

	...
}

... as this if statement no longer evaluates to true (CTScriptControl::Invoke never runs in my use case?).

STDMETHODIMP CteActiveScriptSite::OnScriptError(IActiveScriptError *pscripterror)
{
	...

	if (m_pSC->m_pEI) {
		try {
			if SUCCEEDED(pscripterror->GetExceptionInfo(m_pSC->m_pEI)) {
				m_pSC->m_hr = DISP_E_EXCEPTION;
			}
		}
		catch (...) {
			m_pSC->m_hr = DISP_E_EXCEPTION;
		}
	}
	...
}

Not sure if this fix may affect other functions like:

HRESULT CTScriptControl::SetScriptError(int n)

Also I have seen that this pull request is related to m_pEI.

  • Crash passing empty argument list to Run function:

app. c++

BSTR bsScript = ::SysAllocString(L"function eyePos() { return new Array(0, 1, 2);	}");
script_control->AddCode(bsScript);
::SysFreeString(bsScript);

...
//lenght is 0 for no arguments
ULONG length = sizeof...(_Args);
CComSafeArray<VARIANT> params{length};

try {
      return Ret(m_script_control->Run(uT(func), params.GetSafeArrayPtr()));
} catch (_com_error& e) {
     if (e.Error() == DISP_E_UNKNOWNNAME) {
       throw script_error(
           PFC_string_formatter() << "Error: Function " << func << "() not found.");
     } else {
        rethrow_error(e);
     }
}

The code runs in 32bit mode but crashes on 64bit.

Issue was solved at first by adding a dummy argument to the parameters, then applied the following modification:

(nArg is set to -1 for empty parameter list)

STDMETHODIMP CTScriptControl::raw_Run(BSTR ProcedureName, SAFEARRAY ** Parameters, VARIANT *pvarResult)
{
	...
	if (*Parameters) {
		::SafeArrayGetUBound(*Parameters, 1, &nArg);
		nArg++;
		if (nArg > 0) {
			pv2 = GetNewVARIANT(nArg);
			...
		}
	}
	...
}

That´s it... thanks again for the great job!

I'll be grateful if you find the time to review this pull request,

Best regards

@ghuDaYuYu ghuDaYuYu changed the title fix unhandled exception (empty arguements and initialized m_pEI) fix unhandled exception (empty arguments and uninitialized m_pEI) Sep 7, 2022
@tablacus tablacus merged commit b61c521 into tablacus:master Sep 7, 2022
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2 participants

@ghuDaYuYu @tablacus