Re: Access Denied error on calling CFile::GetStatus() function

From:

"Tom Serface" <tom.nospam@camaswood.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 24 Mar 2007 07:28:32 -0700

Message-ID:

<AC8B77F5-2D22-4540-9E11-7BA1F730A692@microsoft.com>

In the case where I'm "catching" this, the exception is not coming from MFC.
It is coming from lower than that (I can't remember exactly, but I think it
was in _timezone() or something like that. Anyway, the exception was thrown
by the OS I believe and I tried all kinds of objects and couldn't catch any
of them so I finally just gave up and did it this way. I agree that it
wouldn't be good to do this in normal practice, and it would be nice, in
fact, if they would fix CFile or )_timezone() to catch the exception useful
that I could catch, but it didn't work out that way.

Nice catch though (pun intended). I agree with you in practice and I
normally would only put this after trying to catch every other exception
that I know is possible and most of the time I would log an
UnhandledException() and close the program gently. Something like this:

    try {
         if(OrderManager::getInstance()->cancelOrder(&OrderDesc,true)) {
            // Cancel worked OK
         }
         else {
              // Cancel pending
        }
    }
    // OrderException if problem with order
    catch (OrderException& e) {
         LogCriticalEvent(e);
        // Clean up order
    }
    // OrderValidationException if validation problem with order
    catch (OrderValidationException& e) {
         LogCriticalEvent(e);
        // Clean up order
    }
    catch (BaseException& e) {
         LogCriticalEvent(e);
        // Clean up order
    }
    catch (...) {
         theApp.UnknownException();
        // Send message to main window telling it something happened out of
our control
        // Set flag to close down the thread
        // Send message to close program
    }

In the original case I figured out what is happening with the invalid date
and just replaced that date, in my program, with the current date instead.
I didn't really to quit for this and MFC never catches the exception so it
doesn't really even know about it (that I could see). I've been using this
code since around version 6 without any problems that I can see. Of course,
as I said, this only happens when I try to get status on a file that has
somehow been set with an invalid date (my test file has a date way out in
the future and it's a 'license' file for activation of a product).

Tom

"Norbert Unterberg" <nunterberg@newsgroups.nospam> wrote in message
news:O0JfuKebHHA.4000@TK2MSFTNGP02.phx.gbl...

Tom Serface schrieb:

    // convert times as appropriate
    try {
         rStatus.m_ctime = CTime(findFileData.ftCreationTime);
    }
    catch(...) {
         rStatus.m_ctime = CTime::GetCurrentTime();
    }

Tom,

it is bad style and in this case a bug to use catch(...) like this.
Since MFC is throwing exceptions using new, the catch handler needs ro
release the memory owned by the exception, otherwise you'll get a memory
leak. The CException doc notes this: "If an exception is caught by using a
catch keyword, it is not automatically deleted."

To catch any MFC exception, use code like this:

try {
   so_something();
}
catch (CException* e) {
   clean_up_mess();
   e->Delete();
}

Norbert