发现MFC源代码ClistCtrl::GetItemText(int nItem, int nSubItem)有问题

[firefly3233]

以下是MFC中关于ClistCtrl::GetItemText(int nItem, int nSubItem)
的源代码，在调试中，我发现如果一个子项文本长度超过256个时，就读取不完整，查看了源代码，发现确实有问题。

CString ClistCtrl::GetItemText(int nItem, int nSubItem) const
{
	LVITEM lvi;
	memset(&lvi, 0, sizeof(LVITEM));
	lvi.iSubItem = nSubItem;
	CString str;
	int nLen = 128;
	int nRes;
	do
	{
		nLen *= 2;
		lvi.cchTextMax = nLen;
		lvi.pszText = str.GetBufferSetLength(nLen);
		nRes  = (int)::SendMessage(GetListCtrl().m_hWnd, LVM_GETITEMTEXT, (WPARAM)nItem,
			(LPARAM)&lvi);
	} while (nRes == nLen-1);
	str.ReleaseBuffer();
	return str;
}

看这句：while (nRes == nLen-1);
这里为什么要减1，LVM_GETITEMTEXT返回的是读取的字节大小，如果等于我们预设的值，证明还没读完，所以应是：
while (nRes == nLen);

我重写了这段代码，调用读取长数据时，一切正常。
大家看看MFC这段源代码，是不是和我说的一样？

[Eleven]

typedef struct _LVITEM { 
    UINT mask; 
    int iItem; 
    int iSubItem; 
    UINT state; 
    UINT stateMask; 
    LPTSTR pszText; 
    int cchTextMax; 
    int iImage; 
    LPARAM lParam;
#if (_WIN32_IE >= 0x0300)
    int iIndent;
#endif
#if (_WIN32_WINNT >= 0x560)
    int iGroupId;
    UINT cColumns; // tile view columns
    PUINT puColumns;
#endif
#if (_WIN32_WINNT >= 0x0600)
    int* piColFmt;
    int iGroup;
#endif
} LVITEM, *LPLVITEM; 

pszText
If the structure specifies item attributes, pszText is a pointer to a null-terminated string containing the item text. When responding to an LVN_GETDISPINFO notification, be sure that this pointer remains valid until after the next notification has been received.

If the structure receives item attributes, pszText is a pointer to a buffer that receives the item text. Note that although the list-view control allows any length string to be stored as item text, only the first 260 TCHARs are displayed.

If the value of pszText is LPSTR_TEXTCALLBACK, the item is a callback item. If the callback text changes, you must explicitly set pszText to LPSTR_TEXTCALLBACK and notify the list-view control of the change by sending an LVM_SETITEM or LVM_SETITEMTEXT message.