WaitCommEvent Fails Invalid Parameter on Second Pass - c++

Question

My application uses serial I/O with overlapped events. For some reason, ::WaitCommEvent fails consistently on the second pass through the loop with ERROR_INVALID_PARAMETER. If anyone can explain what I need to do differently, it would be greatly appreciated. My serial port initialization/open code and the thread function follows. It should be noted that the init/open code is executed after the thread function is started, which is what the call to ::WaitForSingleObject for.
Additionally, I was wondering if something like ::WaitForSingleObject( pobjSerialPort->m_hSerialPort, INFINITE ); would be valid as a non-blocking means of determining when the serial port is open.
Serial Port Initialization:
DWORD CSerialPort::Open( const wchar_t * portName )
{
DCB dcb = {0};
DWORD dwError = ERROR_SUCCESS;
do
{
if ( this->IsOpen() != FALSE )
{
TRACE(_T("CSerialPort::Open : Warning: Attempted to re-open serial port that is already open.\r\n"));
continue;
}
// Overwrite port name if specified.
if ( portName != NULL )
{
this->m_pwcPortName.clear();
this->m_pwcPortName.append( SP_NAME_PREFIX );
this->m_pwcPortName.append( portName );
}
ASSERT(this->m_pwcPortName.length() > 0);
// Open the serial port.
if ( (this->m_hSerialPort = ::CreateFile(
m_pwcPortName.c_str(), // Formatted serial port name
GENERIC_READ | GENERIC_WRITE, // Access: Read and write
0, // Share: No sharing
NULL, // Security: None
OPEN_EXISTING, // COM port already exists
FILE_FLAG_OVERLAPPED, // Asynchronous I/O
NULL // No template file for COM port
)) == INVALID_HANDLE_VALUE )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to get the handle to the serial port.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Initialize the DCB structure with COM port parameters.
if ( !::BuildCommDCB( _T("baud=38400 parity=N data=8 stop=1"), &dcb ) )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to build the DCB structure.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Set the serial port communications events mask.
if ( !::SetCommMask( this->m_hSerialPort, SP_COMM_MASK ) )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to set comm. events to be monitored.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Set serial port parameters.
if ( !::SetCommState( this->m_hSerialPort, &dcb ) )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to set the comm state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Set the serial port communications timeouts.
this->m_ct.ReadIntervalTimeout = MAXDWORD;
this->m_ct.ReadTotalTimeoutMultiplier = 0;
this->m_ct.ReadTotalTimeoutConstant = 0;
this->m_ct.WriteTotalTimeoutMultiplier = 0;
this->m_ct.WriteTotalTimeoutConstant = 0;
if ( !::SetCommTimeouts( this->m_hSerialPort, &(this->m_ct) ) )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to set the comm timeout values.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Create thread to receive data.
if ( (this->m_hSpRxThread = CreateThread(
NULL, // No security attributes.
0, // Use default initial stack size.
reinterpret_cast<LPTHREAD_START_ROUTINE>(SerialPortRxThreadFn), // Function to execute in new thread.
this, // Thread parameters.
0, // Use default creation settings.
NULL // Thread ID is not needed.
)) == NULL )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to create serial port receive thread.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Create thread to transmit data.
if ( (this->m_hSpTxThread = CreateThread(
NULL, // No security attributes.
0, // Use default initial stack size.
reinterpret_cast<LPTHREAD_START_ROUTINE>(SerialPortTxThreadFn), // Function to execute in new thread.
this, // Thread parameters.
0, // Use default creation settings.
NULL // Thread ID is not needed.
)) == NULL )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to create serial port transmit thread.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
if ( !::SetEvent( this->m_hSpPortOpenEvent ) )
{
dwError = ::GetLastError();
TRACE(_T("CSerialPort::Open : Failed to set event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
while ( 0 );
return dwError;
}
Serial Port Communications Events Thread:
static DWORD SerialPortCommEvtsThreadFn( void * pParam )
{
CSerialPort * pobjSerialPort = NULL;
BOOL blContinue = TRUE;
DWORD dwError = ERROR_SUCCESS;
DWORD dwEventMask = 0;
DWORD dwObjectWaitState;
OVERLAPPED ovComm = { 0 };
int i = 0;
static HANDLE pHandles[SPCM_MAX_EVENTS + SP_ONE_ITEM]; // +1 for overlapped event
// Validate parameters.
if ( pParam == NULL )
{
dwError = ERROR_INVALID_PARAMETER;
TRACE(_T("SerialPortTxThreadFn : Invalid parameter.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
pobjSerialPort = (CSerialPort *)pParam;
// Load event handles.
pHandles[i++] = pobjSerialPort->GetCommHandle( SPCM_THREAD_EXIT_EVT_ID );
pHandles[i++] = pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID );
pHandles[i++] = pobjSerialPort->GetCommHandle( SPCM_PORT_CLOSED_EVT_ID );
while ( (blContinue != FALSE) && (dwError == ERROR_SUCCESS) )
{
// Wait for serial port to open.
if ( (dwObjectWaitState = ::WaitForSingleObject( pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID ), INFINITE )) != WAIT_OBJECT_0 )
{
dwError = ( dwObjectWaitState == WAIT_FAILED ) ? ::GetLastError() : dwObjectWaitState;
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
if ( ovComm.hEvent == NULL )
{
// Create event object for serial port communications events OVERLAPPED structure.
if ( (ovComm.hEvent = ::CreateEvent(
NULL, // No security
TRUE, // Create a manual-reset event object
FALSE, // Initial state is non-signaled
NULL // No name specified
)) == NULL )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to create event object.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
pHandles[i++] = ovComm.hEvent;
}
else
{
i++;
}
// Wait for a communications event.
if ( !::WaitCommEvent( pobjSerialPort->m_hSerialPort, &dwEventMask, &ovComm ) )
{
if ( (dwError = ::GetLastError()) != ERROR_IO_PENDING )
{
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for communications event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
else
{
dwError = ERROR_SUCCESS;
}
}
else
{
if ( (dwError = HandleCommOvEvent( pobjSerialPort, dwEventMask )) != ERROR_SUCCESS )
{
TRACE(_T("SerialPortCommEvtsThreadFn : Failed handling communications event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
continue;
}
dwObjectWaitState = ::WaitForMultipleObjects( i--, pHandles, FALSE, INFINITE );
switch ( dwObjectWaitState )
{
case WAIT_OBJECT_0 + SPCM_THREAD_EXIT_EVT_ID:
blContinue = FALSE;
break;
case WAIT_OBJECT_0 + SPCM_PORT_OPEN_EVT_ID:
if ( !::ResetEvent( pobjSerialPort->GetCommHandle( SPCM_PORT_CLOSED_EVT_ID ) ) )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to reset event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
break;
case WAIT_OBJECT_0 + SPCM_PORT_CLOSED_EVT_ID:
if ( !::ResetEvent( pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID ) ) )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to reset event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
break;
case WAIT_OBJECT_0 + SPCM_MAX_EVENTS:
if ( (dwError = HandleCommOvEvent( pobjSerialPort, dwEventMask )) != ERROR_SUCCESS )
{
TRACE(_T("SerialPortCommEvtsThreadFn : Failed handling communications event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
::CloseHandle( ovComm.hEvent );
::memset( &ovComm, 0, sizeof(OVERLAPPED) );
break;
default:
dwError = ( dwObjectWaitState == WAIT_FAILED ) ? ::GetLastError() : dwObjectWaitState;
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
break;
}
}
return dwError;
}
Handle Comm Events Function
static DWORD HandleCommOvEvent( CSerialPort * pobjSerialPort, DWORD dwEvtMask )
{
DWORD dwError = ERROR_SUCCESS;
do
{
// Validate parameters.
if ( pobjSerialPort == NULL )
{
dwError = ERROR_INVALID_PARAMETER;
TRACE(_T("HandleCommEvent : Invalid parameter.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// Handle the transmit complete event.
if ( dwEvtMask & EV_TXEMPTY )
{
if ( (dwError = HandleTxDoneCommEvent( pobjSerialPort )) != ERROR_SUCCESS )
{
TRACE(_T("HandleCommEvent : Failed handling transmit complete event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
// Handle the received data event.
if ( dwEvtMask & EV_RXCHAR )
{
if ( (dwError = HandleRxDataCommEvent( pobjSerialPort )) != ERROR_SUCCESS )
{
TRACE(_T("HandleCommEvent : Failed handling received data event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
}
while ( 0 );
return dwError;
}
Handle Received Data Comm Event Function
static DWORD HandleRxDataCommEvent( CSerialPort * pobjSerialPort )
{
DWORD dwError = ERROR_SUCCESS;
do
{
// Validate parameters.
if ( pobjSerialPort == NULL )
{
dwError = ERROR_INVALID_PARAMETER;
TRACE(_T("HandleRxDataCommEvent : Invalid parameter.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
if ( !::SetEvent( pobjSerialPort->GetRxHandle( SPRX_RECEIVED_DATA_EVT_ID ) ) )
{
dwError = ::GetLastError();
TRACE(_T("HandleRxDataCommEvent : Failed setting event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
while ( 0 );
return dwError;
}
Receive Thread Function
static DWORD SerialPortRxThreadFn( void * pParam )
{
CSerialPort * pobjSerialPort = NULL;
BOOL blContinue = TRUE;
DWORD dwError = ERROR_SUCCESS;
DWORD dwEventMask = 0;
DWORD dwObjectWaitState;
OVERLAPPED ovComm = { 0 };
int i = 0;
static BYTE pBuf[SP_RX_BUF_SIZE];
static HANDLE pHandles[SPRX_MAX_EVENTS + SP_ONE_ITEM]; // +1 for overlapped event
ASSERT(s_pobjRxBuffer != NULL);
// Validate parameters.
if ( pParam == NULL )
{
dwError = ERROR_INVALID_PARAMETER;
TRACE(_T("SerialPortRxThreadFn : Invalid parameter.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
pobjSerialPort = (CSerialPort *)pParam;
// Load event handles.
pHandles[i++] = pobjSerialPort->GetRxHandle( SPRX_THREAD_EXIT_EVT_ID );
pHandles[i++] = pobjSerialPort->GetRxHandle( SPRX_RECEIVED_DATA_EVT_ID );
while ( (blContinue != FALSE) && (dwError == ERROR_SUCCESS) )
{
if ( ovComm.hEvent == NULL )
{
// Create event object for serial port communications events OVERLAPPED structure.
if ( (ovComm.hEvent = ::CreateEvent(
NULL, // No security
TRUE, // Create a manual-reset event object
FALSE, // Initial state is non-signaled
NULL // No name specified
)) == NULL )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortRxThreadFn : Failed to create event object.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
pHandles[i++] = ovComm.hEvent;
}
else
{
i++;
}
dwObjectWaitState = ::WaitForMultipleObjects( i--, pHandles, FALSE, INFINITE );
switch ( dwObjectWaitState )
{
case WAIT_OBJECT_0 + SPRX_THREAD_EXIT_EVT_ID:
blContinue = FALSE;
break;
case WAIT_OBJECT_0 + SPRX_RECEIVED_DATA_EVT_ID:
if ( !::ReadFile( pobjSerialPort->m_hSerialPort, pBuf, SP_RX_BUF_SIZE, NULL, &ovComm ) )
{
if ( (dwError = ::GetLastError()) != ERROR_IO_PENDING )
{
TRACE(_T("SerialPortRxThreadFn : Failed reading data from serial port.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
else
{
if ( (dwError = HandleReceivedDataOvEvent( pobjSerialPort, &ovComm, pBuf )) != ERROR_SUCCESS )
{
TRACE(_T("SerialPortRxThreadFn : Failed handling serial port received data event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
}
break;
case WAIT_OBJECT_0 + SPRX_MAX_EVENTS:
if ( (dwError = HandleReceivedDataOvEvent( pobjSerialPort, &ovComm, pBuf )) != ERROR_SUCCESS )
{
TRACE(_T("SerialPortRxThreadFn : Failed handling serial port received data event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
::CloseHandle( ovComm.hEvent );
::memset( &ovComm, 0, sizeof(OVERLAPPED) );
break;
default:
dwError = ( dwObjectWaitState == WAIT_FAILED ) ? ::GetLastError() : dwObjectWaitState;
TRACE(_T("SerialPortRxThreadFn : There is a problem with the OVERLAPPED structure's event handle.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
break;
}
}
return dwError;
}

Answer 1

Looks like you're trying to use the same OVERLAPPED structure for both WaitCommEvent and ReadFile. That should be causing you no end of problems.
Documentation citation: When performing multiple simultaneous overlapped operations on a single thread, the calling thread must specify an OVERLAPPED structure for each operation
An attempt to fix it (not tested, not even compiled). Stuff you need to fill in specific to your project is marked with // TODO.
static DWORD SerialPortCommEvtsThreadFn( void * pParam )
{
CSerialPort * pobjSerialPort = NULL;
BOOL blContinue = TRUE;
DWORD dwError = ERROR_SUCCESS;
DWORD dwEventMask = 0;
DWORD dwObjectWaitState;
OVERLAPPED ovWaitComm = { 0 };
OVERLAPPED ovRead = { 0 };
const DWORD numHandles = SPCM_MAX_EVENTS + 2;
HANDLE pHandles[numHandles];
// Validate parameters.
if ( pParam == NULL )
{
dwError = ERROR_INVALID_PARAMETER;
TRACE(_T("SerialPortTxThreadFn : Invalid parameter.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
pobjSerialPort = static_cast<CSerialPort *>(pParam);
ovWaitComm.hEvent = ::CreateEvent(NULL, FALSE, FALSE, NULL);
ovRead.hEvent = ::CreateEvent(NULL, FALSE, FALSE, NULL);
if (!ovWaitComm.hEvent || !ovRead.hEvent) {
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to create event objects.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
// Load event handles.
pHandles[SPCM_THREAD_EXIT_EVT_ID ] = pobjSerialPort->GetCommHandle( SPCM_THREAD_EXIT_EVT_ID );
pHandles[SPCM_PORT_OPEN_EVT_ID ] = pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID );
pHandles[SPCM_PORT_CLOSED_EVT_ID ] = pobjSerialPort->GetCommHandle( SPCM_PORT_CLOSED_EVT_ID );
pHandles[numHandles - 2] = ovWaitComm.hEvent;
pHandles[numHandles - 1] = ovRead.hEvent;
// Wait for serial port to open.
if ( (dwObjectWaitState = ::WaitForSingleObject( pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID ), INFINITE )) != WAIT_OBJECT_0 ) {
dwError = ( dwObjectWaitState == WAIT_FAILED ) ? ::GetLastError() : dwObjectWaitState;
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
// TODO: SetCommTimeouts
// Wait for a communications event.
if ( !::WaitCommEvent( pobjSerialPort->m_hSerialPort, &dwEventMask, &ovWaitComm ) {
if ( (dwError = ::GetLastError()) != ERROR_IO_PENDING ) {
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for communications event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
return dwError;
}
}
// TODO: Here, call ReadFile, passing &ovRead
dwError = ERROR_SUCCESS;
while ( blContinue && (dwError == ERROR_SUCCESS) )
{
dwObjectWaitState = ::WaitForMultipleObjects( numHandles, pHandles, FALSE, INFINITE );
switch ( dwObjectWaitState )
{
case WAIT_OBJECT_0 + SPCM_THREAD_EXIT_EVT_ID:
blContinue = FALSE;
break;
case WAIT_OBJECT_0 + SPCM_PORT_OPEN_EVT_ID:
if ( !::ResetEvent( pobjSerialPort->GetCommHandle( SPCM_PORT_CLOSED_EVT_ID ) ) )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to reset event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
break;
case WAIT_OBJECT_0 + SPCM_PORT_CLOSED_EVT_ID:
if ( !::ResetEvent( pobjSerialPort->GetCommHandle( SPCM_PORT_OPEN_EVT_ID ) ) )
{
dwError = ::GetLastError();
TRACE(_T("SerialPortCommEvtsThreadFn : Failed to reset event object signal state.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
break;
case WAIT_OBJECT_0 + numHandles - 2:
if ( (dwError = HandleCommOvEvent( pobjSerialPort, dwEventMask )) != ERROR_SUCCESS )
{
TRACE(_T("SerialPortCommEvtsThreadFn : Failed handling communications event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
continue;
}
// TODO: call WaitCommEvent again, if HandleCommOvEvent didn't already
break;
case WAIT_OBJECT_0 + numHandles - 1:
// TODO: do something with the received data, it's now in the buffer supplied to ReadFile
// TODO: call ReadFile again
break;
default:
dwError = ( dwObjectWaitState == WAIT_FAILED ) ? ::GetLastError() : dwObjectWaitState;
TRACE(_T("SerialPortCommEvtsThreadFn : Failed waiting for event.\r\n\tError: %d\r\n\tFile: %s\r\n\tLine: %d\r\n"), dwError, _T(__FILE__), __LINE__);
break;
}
}
return dwError;
}

Answer 2

It looks like you're calling GetLastError() when you haven't checked that there's been an error.

Answer 3

You are calling
WaitCommEvent(pobjSerialPort->m_hSerialPort, &dwEventMask, &(pobjSerialPort->m_ovEvents))
The 1st and 3rd parameters of WaitCommEvent are input parameters, However you did not supply their initialization code.
How do you initialize m_hSerialPort? Do you call CreateFile with valid params and verify there is no error?
How do you initialize m_ovEvents? Do you call CreateEvent with valid params and verify there is no error?
Since you're getting ERROR_INVALID_PARAMETER, I think your problem is in the initialization of one of these parameters.