刚刚开始用ATL写COM组件,遇到RtlSizeHeap问题

最新推荐文章于 2024-03-25 09:37:46 发布

原创最新推荐文章于 2024-03-25 09:37:46 发布 · 1.5k 阅读

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文章标签：

#pointers #function #variables #object #string #null

本文介绍了一个关于COM组件中使用_bstr_t类型成员变量导致RtlSizeHeap问题的案例。通过详细分析问题产生的原因及解决方案，帮助读者理解如何正确地管理和释放COM对象中的字符串资源。

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刚刚开始用ATL写COM组件,遇到RtlSizeHeap,RtlReeHeap问题

去网上Google一下 ATL RtlSizeHeap

在www.codguru.com上有位大哥给出了这个

bafraser - As it turns out, I was able to determine why I was getting this RTLSizeHeap problem. Being a novice to COM and ATL, I had a class that stored a string (_bstr_t) value. As you would expect, I had the normal get_ and put_ functions to operate on the member. The problem was, my get_ did not send back a copy of the string held onto by the _bstr_t member that I had set up. All I did was assign it (thinking the operator = function actually makes a copy). Since I was using smart pointers, I had the result of the get_ function assigned to another _bstr_t. The problem...both _bstr_t values were looking at the same memory. So no problem would occur when the first object goes out of scope as the first _bstr_t frees the memory it was holding, but when the second object would go out of scope...bam RtlSizeHeap problem - since the second _bstr_t was still pointing to memory that was now freed. To solve this, my get_ function was changed to:

STDMETHODIMP CSomeClass::get_m_sToTime(BSTR *pVal)
{
AFX_MANAGE_STATE(AfxGetAppModuleState())
if (pVal)
*pVal = bstrtToTime.copy();
return S_OK;
}

Summary - RtlSizeHeap is definitely not lying - Most certainly this error is the result of BSTRs and _bstr_t variables not being handled appropriately. Double and tripple check your code - It took me a long time to find this!

Hope this helps!
Dan

嗯,谢谢Dan,原因大概是某个传出的参数,使用的是栈内存.

找找,果然发现是

STDMETHOD(get_Name)(BSTR * Name)
{
   if (Name == NULL)
   return E_POINTER;
  *Name=bstrName=_T("设备树");
  return S_OK;
}

修改为:

STDMETHOD(get_Name)(BSTR * Name)
{
  CComBSTR bstrName(_T("设备树"));
  if (Name == NULL)
   return E_POINTER;
  *Name=bstrName.Copy();
  return S_OK;
}

搞定!!