Device notifications in a service

EDN Admin · Jul 14, 2008

Hi guys,

I need to read the disk drive letter when a USB drive is inserted in a windows service.

The code I used ina sample MFC program raises three events for DBT_DEVICEARRIVAL, two for DBT_DEVTYP_DEVICEINTERFACE and one for DBT_DEVTYP_VOLUME.

But the I get only two events in a windows service for DBT_DEVTYP_DEVICEINTERFACE. I do not get the drive letter because DBT_DEVTYP_VOLUME event is never raised. Here is the Registration code and event handler code.

Is there any reason for this behaviour???


bool CeTCaptureControlService::RegisterForUsbMessages(void)
{ 
DEV_BROADCAST_DEVICEINTERFACE NotificationFilter;
HDEVNOTIFY hDeviceNotify = NULL;
static const GUID GuidDevInterfaceList[] =
{
{ 0xa5dcbf10, 0x6530, 0x11d2, { 0x90, 0x1f, 0x00, 0xc0, 0x4f, 0xb9, 0x51, 0xed } },
{ 0x53f56307, 0xb6bf, 0x11d0, { 0x94, 0xf2, 0x00, 0xa0, 0xc9, 0x1e, 0xfb, 0x8b } },
{ 0x4d1e55b2, 0xf16f, 0x11Cf, { 0x88, 0xcb, 0x00, 0x11, 0x11, 0x00, 0x00, 0x30 } },
{ 0xad498944, 0x762f, 0x11d0, { 0x8d, 0xcb, 0x00, 0xc0, 0x4f, 0xc3, 0x35, 0x8c } }
};
ZeroMemory(&NotificationFilter, sizeof(NotificationFilter));
NotificationFilter.dbcc_size = sizeof(DEV_BROADCAST_DEVICEINTERFACE);
NotificationFilter.dbcc_devicetype = DBT_DEVTYP_DEVICEINTERFACE;
for (int i = 0; i < sizeof(GuidDevInterfaceList); i++)
{
NotificationFilter.dbcc_classguid = GuidDevInterfaceList;
hDeviceNotify = RegisterDeviceNotification(/*m_hWnd*/m_hServiceStatus, &NotificationFilter,
DEVICE_NOTIFY_SERVICE_HANDLE/*DEVICE_NOTIFY_WINDOW_HANDLE*/);
if (hDeviceNotify == NULL)
{
ATLTRACE2("Device Notify registration failed with error %d.n", GetLastError());
this->LogMessage("Device Notify registration failed.", true, 0);
return false;
}
}
//END Register Code 
return true;
} ///HANDLER code

DWORD CService::Handler(DWORD dwOpcode, DWORD evtype, PVOID evdata, PVOID Context)
{
switch (dwOpcode)
{
case SERVICE_CONTROL_DEVICEEVENT:
{
PDEV_BROADCAST_HDR pHdr = (PDEV_BROADCAST_HDR) evdata/*lParam*/;
char szMessage[80];
char cDriveLetter;
if(pHdr)
{
wsprintf(szMessage, "Device type is %d.n", pHdr->dbch_devicetype);
MessageBox(NULL, szMessage, "", 0);
}
switch (evtype)
{
case DBT_DEVICEARRIVAL:
// Handle device arrival 
if(pHdr)
{
/*wsprintf(szMessage, "Device type is %d.n", pHdr->dbch_devicetype);
MessageBox(NULL, szMessage, "", 0);*/ 
if (pHdr->dbch_devicetype == DBT_DEVTYP_VOLUME)
{
PDEV_BROADCAST_VOLUME pVol = (PDEV_BROADCAST_VOLUME) pHdr;

cDriveLetter = GetDriveLetter(pVol->dbcv_unitmask);
sprintf_s(szMessage, "Device %c: has been inserted.", cDriveLetter);
MessageBox(NULL, szMessage, "USB Notice", MB_OK);
}
}
MessageBox(NULL, "Device Inserted.", "", 0);
break;
case DBT_DEVICEREMOVECOMPLETE:
// Handle device removal 
MessageBox(NULL, "Device Removed.", "", 0);
break;
}
break;
}
return NO_ERROR;
} 

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Device notifications in a service

EDN Admin

Well-known member