Load Printer Driver dynamically

NTDEV
1

Hi,

I have written a printer driver, which is installed and starts.
As it does nothing in reality, I want to load a real printer driver in:
DrvEnablePDEV with the EngLoadImage call and get the functiontable from that driver via a call to the DrvEnableDriver. To get the address of DrvEnableDriver I planned to use EngFindImageProcAddress.

I did this successfully within a display driver.

Here in a printer driver I failed so far. The codesnippet which does this job follows. Well it is stripped down a lot to the important part.

PVOID pv;
HANDLE hDll;
LPWSTR pwstr = L"PRINTERDRIVER.DLL";
PF_DRV_ENABLE_DRIVER pfDrvEnableDriver;

hDll = EngLoadImage( pwstr );

if ( !hDll ) { … Errorhandling with exit… }

pv = EngFindImageProcAddress( hDll, “DrvEnableDriver”);
pfDrvEnableDriver = (PF_DRV_ENABLE_DRIVER)pv;

if (pfDrvEnableDriver)
{
bRet = pfDrvEnableDriver( iEngineVersion, sizeof(DRVENABLEDATA), &ded );
}

The dll I want to load is in the directory specified in the document, i.e. somwhere under system32…, but it does not get loaded.
Any ideas?

Thanks a lot

/Kucki

2

Kucki,

Maybe you need to specify the full path of the dll not only the file name.

Also, maybe because printer drivers can be User Mode or Kernel Mode. You wrapper shall be prepared to handle
both cases. In the case of a User Mode driver you can load it as a regular dll (LoadLibrary / GetProcAddress)

Check this link about Kernel Mode vs User Mode:
http://msdn.microsoft.com/library/en-us/graphics/hh/graphics/drvarch_2ief.asp

And check this link about printer drivers versioning:
http://msdn.microsoft.com/library/en-us/graphics/hh/graphics/prtinst_4s6f.asp

Regards,
Dan.

Hi,

I have written a printer driver, which is installed and starts.
As it does nothing in reality, I want to load a real printer driver in:
DrvEnablePDEV with the EngLoadImage call and get the functiontable from that driver via a call to the DrvEnableDriver.
To get the address of DrvEnableDriver I planned to use EngFindImageProcAddress.

I did this successfully within a display driver.

Here in a printer driver I failed so far. The codesnippet which does this job follows. Well it is stripped down a lot
to the important part.

PVOID pv;
HANDLE hDll;
LPWSTR pwstr = L"PRINTERDRIVER.DLL";
PF_DRV_ENABLE_DRIVER pfDrvEnableDriver;

hDll = EngLoadImage( pwstr );

if ( !hDll ) { … Errorhandling with exit… }

pv = EngFindImageProcAddress( hDll, “DrvEnableDriver”);
pfDrvEnableDriver = (PF_DRV_ENABLE_DRIVER)pv;

if (pfDrvEnableDriver)
{
bRet = pfDrvEnableDriver( iEngineVersion, sizeof(DRVENABLEDATA), &ded );
}

The dll I want to load is in the directory specified in the document, i.e. somwhere under system32…, but it does not
get loaded.
Any ideas?

Thanks a lot

/Kucki