C / C++ / MFC Discussion Boards

Executing a usermode program from a driver?

Member 469267019-Nov-10 3:36

19-Nov-10 3:36

Hello,

I am hoping that someone might know how to execute a user-mode executable from a driver? Either DDK or for mac.

I have found that neither exec(), fork() or system() work in the DDK. What other compilers could these statements work for (windows/mac)?

Re: Executing a usermode program from a driver?

Luc Pattyn19-Nov-10 6:58

Luc Pattyn

19-Nov-10 6:58

I don't think that can be done (nor should be done) directly, as the protection would be insufficient. Maybe the driver could get it scheduled through Windows Scheduler though, I don't really know.

Smile | :)

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Re: Executing a usermode program from a driver?

«_Superman_»19-Nov-10 7:19

«_Superman_»

19-Nov-10 7:19

There is no direct way to do this directly from a driver.
Usually there is a support application or service that runs in user mode and waits on a named event.
The driver then signals this event whenever a process needs to be created.
In the user mode app, the wait is satisfied and it creates the process.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Polymorphism in C

Re: Executing a usermode program from a driver?

CPallini19-Nov-10 9:06

CPallini

19-Nov-10 9:06

Why?

If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.

This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke

[My articles]

Re: Executing a usermode program from a driver?

Member 469267019-Nov-10 10:50

Member 4692670

19-Nov-10 10:50

The purpose would to be to run a portal program for all the applications on a storage device.

The best way to use worker thread to connect to an database

mesajflaviu19-Nov-10 3:01

mesajflaviu

19-Nov-10 3:01

What is the best way to connect an database through an worker thread ?
I teach from here[^] how to use an worker thread ...
Ok , but in worker thread I use theApp global member variable which have an database connection ... but the problem is that not every time thread unconnect database or destroy theApp.m_pDB member variable from CMyApp::ExitInstance() event .... I don't know why ?!

So , can you tell me how to connect to an database from an worker thread ? Thank you !

Re: The best way to use worker thread to connect to an database

David Crow19-Nov-10 4:13

David Crow

19-Nov-10 4:13

mesajflaviu wrote:
So , can you tell me how to connect to an database from an worker thread ?

I would be inclined to connect to the database in the primary thread, and then pass the CDatabase pointer to the secondary thread.

"One man's wage rise is another man's price increase." - Harold Wilson

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Re: The best way to use worker thread to connect to an database

mesajflaviu19-Nov-10 6:44

mesajflaviu

19-Nov-10 6:44

Connection to database I make in primary thread ... and now , since I discover threads Big Grin | :-D

, I try to switch connection to an worker thread ...
Ok , I have connection attach it to global theApp variable ... ex : theApp.ExecuteSQL(...) , theApp.GetData(...) , etc. so , you say to pass this varaible ( theApp ) as parameter to worker thread ? Since theApp is global variable , what is the point ?

Re: The best way to use worker thread to connect to an database

David Crow19-Nov-10 7:43

David Crow

19-Nov-10 7:43

mesajflaviu wrote:
so , you say to pass this varaible ( theApp ) as parameter to worker thread

Not what I said at all.

Re: The best way to use worker thread to connect to an database

mesajflaviu19-Nov-10 8:23

mesajflaviu

19-Nov-10 8:23

Then , to pass theApp.m_pDB ( CDatabase* kind of ) like parameter to worker thread ?

Sorting CListCtrl with group view enabled

Paul201319-Nov-10 1:20

Paul2013

19-Nov-10 1:20

Hi,

I'm using a CListCtrl in an MFC app (vs2008) that has group view enabled. All works fine on my Win7 PC but when I run my app on a Win XP system the list will not sort the list items when group view is enabled. Is this a WinXP limitation?

Thanks.

Re: Sorting CListCtrl with group view enabled

Richard MacCutchan19-Nov-10 2:53

Richard MacCutchan

19-Nov-10 2:53

I have come across a similar situation recently, but on Windows 7 using straight Win32 API; are you sure it sorts correctly within groups? I found a solution here[^], it may help you also.

Just say 'NO' to evaluated arguments for diadic functions! Ash

Re: Sorting CListCtrl with group view enabled

Paul201319-Nov-10 3:47

Paul2013

19-Nov-10 3:47

Thanks for the reply, Richard. I will try what the link suggests.

PS
I've just doubled checked and it does indeed sort on groups in Win7.

Thanks Smile | :)

Create compatible bitmap

MacCPlus19-Nov-10 0:57

MacCPlus

19-Nov-10 0:57

Hi,

I can't seem to properly create a compatible bitmap in my MFC application. I'm trying to StretchBlt a byte buffer (with 8-bit greyscale pixel information) to a DC, but the only way to get it done is by taking a rather unconventional detour. Here's what I do:

HBITMAP hBmp = (HBITMAP)::LoadImage(NULL, "bitmap.bmp", IMAGE_BITMAP,
    0, 0, LR_LOADFROMFILE | LR_CREATEDIBSECTION);

CBitmap cBmp;
cBmp.Attach(hBmp);
cBmp.SetBitmapBits(m_width*m_height, datap);

CDC dcMem;
dcMem.CreateCompatibleDC(dc);
HBITMAP BitmapOld = (HBITMAP)SelectObject(dcMem, cBmp);
dc->StretchBlt(xOffset, yOffset, m_width*rectSizeX, m_height*rectSizeY, &dcMem, 0, 0, m_width, m_height, SRCCOPY);
dcMem.SelectObject(BitmapOld);
dcMem.DeleteDC();

The file bitmap.bmp contains an uncompressed 8-bit greyscale image with exactly the same dimension of m_width*m_height. So far only by loading this one file first, attaching it to CBitmap cBmp and then calling SetBitmapBits with the pointer to my own byte buffer (datap), thus overwriting the bitmap information from the file, I can create a compatible bitmap out of my byte buffer that I can blit into the window. If I go like this

BITMAPINFO *lpInfo = new BITMAPINFO;
lpInfo->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
lpInfo->bmiHeader.biWidth = m_width;
lpInfo->bmiHeader.biHeight = m_height;
lpInfo->bmiHeader.biPlanes = 1;
lpInfo->bmiHeader.biBitCount = 8;
lpInfo->bmiHeader.biCompression = BI_RGB;
lpInfo->bmiHeader.biSizeImage = m_width*m_height;
lpInfo->bmiHeader.biClrUsed = 0;

HBITMAP hBmp = (HBITMAP)::CreateDIBSection(0, lpInfo, DIB_RGB_COLORS, 0, 0, 0x0);

... and then do the rest mentioned above (Attach(), CreateCompatibleDC(), SelectObject(), StretchBlt() etc.), I see only a greenish version of the image I want to blit (but in right aspect ratio, stride, dimension etc.), and it keeps appearing and disappearing with a blurry spot all the time.

What am I doing wrong?

Mac

Re: Create compatible bitmap [modified]

CPallini19-Nov-10 1:41

CPallini

19-Nov-10 1:41

From "CreateDIBSection Function"[^] documentation:

iUsage [in]
The type of data contained in the bmiColors array member of the BITMAPINFO structure pointed to by pbmi (either logical palette indexes or literal RGB values). The following values are defined.

Value Meaning
DIB_PAL_COLORS
The bmiColors member is an array of 16-bit indexes into the logical palette of the device context specified by hdc.
DIB_RGB_COLORS
The BITMAPINFO structure contains an array of literal RGB values.

Where's your array?
Smile | :)

modified on Friday, November 19, 2010 7:50 AM

Re: Create compatible bitmap

MacCPlus19-Nov-10 2:26

MacCPlus

19-Nov-10 2:26

I'd say it's not there... Wink | ;)

lpInfo->bmiColors[0].rgbBlue=1;
lpInfo->bmiColors[0].rgbGreen=1;
lpInfo->bmiColors[0].rgbRed=1;
lpInfo->bmiColors[0].rgbReserved=0;

... is what I tried. I also iterated over 256 array indices, assigning 1 or 0. Which values do I have to assign? The blitted image looks different, but still more like a "pixel color accident".

Mac

Re: Create compatible bitmap [fixed]

CPallini19-Nov-10 3:03

CPallini

19-Nov-10 3:03

It really depends on your DIB bits (of course you've to assign the whole array).
My naive attempt, would be:

C++

  for (int n=0; n < 256; n++)
  {
    lpInfo->bmiColors[n].rgbBlue=b;
    lpInfo->bmiColors[n].rgbGreen=b;
    lpInfo->bmiColors[n].rgbRed=b;
    lpInfo->bmiColors[n].rgbReserved=0;
    lpInfo->bmiColors[n].rgbBlue=n;
    lpInfo->bmiColors[n].rgbGreen=n;
    lpInfo->bmiColors[n].rgbRed=n;
    lpInfo->bmiColors[n].rgbReserved=0;
  }

modified on Tuesday, November 23, 2010 7:47 AM

Re: Create compatible bitmap

MacCPlus19-Nov-10 4:30

MacCPlus

19-Nov-10 4:30

When I do that, I run into an assertion (at some random point in my application), and in addition I sometimes get an "Out of memory" message.
When I assign only [0] through [9] of the array, I do get a blitted image like described in my original post, but with a very redish touch.

Mac

Re: Create compatible bitmap

CPallini19-Nov-10 6:34

CPallini

19-Nov-10 6:34

Pardon my dumb question: Do you know you should allocate enough memory for the array?
i.e.

BITMAPINFO *lpInfo = (BITMAPINFO *) (new BYTE[sizeof(BITMAPINFO) + 255 * sizeof(RGBQUAD)]);

Re: Create compatible bitmap

MacCPlus21-Nov-10 21:55

MacCPlus

21-Nov-10 21:55

The "dumb" part was on my side, because I didn't allocate any memory. But even though now I don't get an exception anymore, the result is still the same as described on my previous posts.

Mac

Re: Create compatible bitmap

CPallini21-Nov-10 22:06

CPallini

21-Nov-10 22:06

Possibly you should have a look at the palette of the image file (the one you use for the 'unusual approach'). How is the palette defined (i.e. what is the RGBQUAD array content?)

Smile | :)

Re: Create compatible bitmap

MacCPlus22-Nov-10 0:49

MacCPlus

22-Nov-10 0:49

That was exactly what I tried, when I found the "unusual approach": What is different in the RGBQUAD, in the BITMAPHEADER, in the BITMAPINFO if I load the bitmap from the file? You know - so I could assign the exact same properties to my bitmap created with CreateDIBSection. The problem is, I didn't find a way of accessing any of the mentioned structures. The only thing I was able to find out after using LoadImage() was this (also see code from original post):

BITMAP bm;
cBmp.GetBitmap(&bm);

bm was then filled with these values

bmType 0 long
bmWidth 320 long
bmHeight 180 long
bmWidthBytes 320 long
bmPlanes 1 unsigned short
bmBitsPixel 8 unsigned short
bmBits 0x07a10000 void *

No surprise there. I assigned the same values (bmPlanes, bmBitsPixel etc.) to BITMAPINFO *lpInfo (also see original post).
Is there a way of retrieving a "proper" BITMAPINFO or BITMAPINFOHEADER from the bitmap loaded with LoadImage()?

Mac

Re: Create compatible bitmap

CPallini22-Nov-10 1:55

CPallini

22-Nov-10 1:55

MacCPlus wrote:
Is there a way of retrieving a "proper" BITMAPINFO or BITMAPINFOHEADER from the bitmap loaded with LoadImage()?

No, I suppose. Anyway you may retrieve these structures loading the file yourself (see, for instance here - it looks a bit dated, but, at the moment I cannot find an up-to-date one).
Smile | :)

Re: Create compatible bitmap

MacCPlus23-Nov-10 1:43

MacCPlus

23-Nov-10 1:43

I got it!

Had to initialize bmiColors like this:

for (int n=0; n < 256; n++)
{
    m_pBitmapInfo->bmiColors[n].rgbBlue=n;
    m_pBitmapInfo->bmiColors[n].rgbGreen=n;
    m_pBitmapInfo->bmiColors[n].rgbRed=n;
    m_pBitmapInfo->bmiColors[n].rgbReserved=0;
}

Thanks for the advice!
Mac

Re: Create compatible bitmap

CPallini23-Nov-10 1:52

CPallini

23-Nov-10 1:52

It was what I intended here, since they are grey gradations, unfortunately (now I realize) I made a typo (fixed now).
Sorry for the inconvenience.
Smile | :)

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