Re: serial port Writefile: sometimes 998 ERROR_NOACCESS

From:

Oliver Regenfelder <oliver.regenfelder@gmx.at>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 30 Dec 2010 13:18:05 +0100

Message-ID:

<8a4be$4d1c787f$54774a4f$12125@news.inode.at>

Hello,

On 24.12.2010 20:35, mfc wrote:

BOOL CASocThread::InitSerialThreads()
{

for(int i=0; i<16; i++) //the number 16 will be removed /
replaced by a #define

You should also think about a static member of the CAsocThread class
which defines the number of threads, or a parameter to the constructor
(if applicable).

     {

        m_wSerialThreads[i] =
(CSerialWriterThread*)AfxBeginThread(RUNTIME_CLASS(CSerialWriterThread),

THREAD_PRIORITY_NORMAL,
                         0,
             CREATE_SUSPENDED);

        if (m_wSerialThreads[i] == NULL)
        { // failed to start
            TRACE("m_writerThread failed\n");
            return FALSE;
        }

So when one thread fails to start then the m_wSerialThreads array will
contain some threads which are initialized at least one NULL and the
rest will be random data from your memory ?!

You could make the m_wSerialThreads a list and only add created threads,
this way a lot of parts of the software won't need to know
how many threads are there before hand. Because the fixed size array
for sure guarantees a lot of code depending on the size of the
fixed size array.

         CString port;

        if(i< 10)
            port.Format(_T("\\\\.\\COM%d"), i);
        else
            port.Format(_T("\\.\\COM%d"), i);

This should be unnecessary. The log form of comport names
can be used for comports below and above 10.

         HANDLE hCom = ::CreateFile(port, // filename
                        GENERIC_READ | GENERIC_WRITE, // desired access
                        0, // exclusive
                        NULL, // security irrelevant
                        OPEN_EXISTING, // it has to be there
                        0, //FILE_FLAG_OVERLAPPED, // open asynchronous
                        NULL); // template file

        if (hCom == INVALID_HANDLE_VALUE)
        {
            DWORD err = ::GetLastError();
            return FALSE;
        }

You return and there will be a thread created with invalid/random
thread->params data.

Again I would suggest to add a thread to your collection only after
it has been successfully created and completely initialized.

Best regards,

Oliver