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COM and CORBAŽ Side by Side |
Errata
Errors always pop up where you least expect them. This page describes errors
contained in the book.
Page 78 - Attempting to call SysFreeString() with an unset pointer.
Thanks to Tomas Palmer for pointing this out. Here is a code snippet identifying
the problem.
BOOL MyCheckingAccount::Init(const CString& name,
const CString& serverName,
CString& errmsg)
{
Reset();
// Create server info.
COSERVERINFO serverInfo;
COSERVERINFO* pServerInfo;
if ( serverName.IsEmpty() )
{
// Use local server.
pServerInfo = NULL;
}
else
{
serverInfo.dwReserved1 = 0;
serverInfo.dwReserved2 = 0;
serverInfo.pwszName = serverName.AllocSysString();
serverInfo.pAuthInfo = NULL;
pServerInfo = &serverInfo;
}
// Create MULTI_QI array to get all pertinent interfaces.
MULTI_QI mqi[] =
{
{&IID_IAccount, NULL, 0},
{&IID_IAccountInit, NULL, 0},
{&IID_ICheckingAccount, NULL, 0},
};
// Create a server object instance.
HRESULT hr;
hr = CoCreateInstanceEx
(CLSID_Ch3CheckingAccount, NULL,
CLSCTX_LOCAL_SERVER | CLSCTX_REMOTE_SERVER,
pServerInfo, 3, mqi);
::SysFreeString(serverInfo.pwszName); // ****** ERROR ******
Notice that if the serverName argument to Init() is an empty string,
serverInfo.pwszName never gets set. To correct the problem, a check needs to be
made before calling ::SysFreeString(). For example, the check could be written
as shown here:
if ( !serverName.IsEmpty() )
{
::SysFreeString(serverInfo.pwszName);
}
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