C / C++ / MFC

9-Apr-07 14:14

Here is some code I wrote that needs to be called from a Win32 exe. The Win32 exe needs to run on both 9x and NT platforms. The code compiles with no problem on VS 2005, but the DLL will not load when run in 9x.

It runs under NT, and only if I uncomment the "//return" line, will it run under 9x. LsaOpenPolicy is an NT platform API - it's as though the DLL is calling the LsaOpenPolicy even when blocked by an (if) statement on 9x. Is it something obvious I'm missing? I dont' want to create two DLLs, one for 9x and another for NT.

************************* DLL (host.dll) *************************

#include <windows.h>
#include <ntsecapi.h>

NTSTATUS GetLsa();
NTSTATUS ntsTemp;
BOOL bIsNTPlatform;

...

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD dwReason, LPVOID lpvReserved)
{
OSVERSIONINFOEX osvi;
ZeroMemory(&osvi, sizeof(OSVERSIONINFOEX));
osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX);
if (!GetVersionEx((OSVERSIONINFO *) &osvi))
{
osvi.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
if (!GetVersionEx((OSVERSIONINFO *)&osvi))
return FALSE;
}

bIsNTPlatform = (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT);
if (bIsNTPlatform)
ntsTemp = GetLsa();

return TRUE;
}

NTSTATUS GetLsa()
{
LSA_HANDLE hPolicy = LSA_HANDLE(0);
LSA_OBJECT_ATTRIBUTES ObjectAttributes;
//return 1;
return LsaOpenPolicy(NULL, &ObjectAttributes, POLICY_VIEW_LOCAL_INFORMATION, &hPolicy);
}

************************* DLL (host.dll) *************************

************************* VB EXE that calls DLL *************************

Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long
Private Sub Main()

MsgBox LoadLibrary(App.Path & "\host.dll"), , "LoadLibrary")

End Sub

************************* VB EXE that calls DLL *************************

Rick York9-Apr-07 15:54

Rick York

9-Apr-07 15:54

Have you looked at the docs for LsaOpenPolicy ?

"Windows NT/2000/XP: Included in Windows NT 3.51 and later"

JeffRoz9-Apr-07 16:49

9-Apr-07 16:49

Yes, but I only call the function if bIsNTPlatform is TRUE.

Steve S10-Apr-07 0:16

Steve S

10-Apr-07 0:16

But by linking to it, you're asking the loader to fixup the entrypoint when your DLL gets loaded. You could try using GetProcAddress() instead, using proper dynamic linking.

Steve S
Developer for hire

JeffRoz10-Apr-07 3:09

10-Apr-07 3:09

I'm confused, then, b/c the DLL _will_ load on 9x as long as there is a "return" before the NT-only API call.

And what do you mean by "proper"?

JudyL_MD10-Apr-07 7:36

JudyL_MD

10-Apr-07 7:36

I'm not Steve, but I'll take a crack at explaining this. The fact that you have a return in your code before you call function X does not affect what the OS does when it tries to load your program. All it has is a list of functions that your program needs to run - that list is created when the program is linked together. If any function in that list is not available when the OS tries to load your program, it will fail.

Steve's use of the term "proper dynamic linking" is made to distinguish it from what you get when you use an import library. You link with the .lib and that .lib contains references to the DLL it is associated with. However, as you've found out, it creates dependencies on functions that you may not use _at execution time_. "Proper" does not create that dependency at the expense of making more work for you in your program. You'll need to do something like:

if os is nt or greater
{
LoadLibrary ("the name of the dll containing the function")
GetProcAddress (handle from LoadLibrary, "name of function");
(function pointer from GetProcAddress) (parameters to function)
}
else
{
whatever you do in the windows 95 and 98 case
}

This way, the function in question is not in the list of functions that the OS tries to resolve when your program is loaded.

Judy

JeffRoz10-Apr-07 8:43

10-Apr-07 8:43

Ohhhhh...ok. I will give that a try, then. Interesting that on 9x the code works if the "return 1" is uncommented, and fails when it is commented?

So like this?

typedef NTSTATUS (NTAPI *PLSAOPENPOLICY)(PLSA_UNICODE_STRING, PLSA_OBJECT_ATTRIBUTES, ACCESS_MASK, PLSA_HANDLE);
PLSAOPENPOLICY pLsaOpenPolicy = NULL;

h32 = LoadLibrary(TEXT("advapi32.dll"));
if (h32)
{
pLsaOpenPolicy = (PLSAOPENPOLICY) GetProcAddress(hAdvApi32,"LsaOpenPolicy");

pLsaOpenPolicy(NULL,&ObjectAttributes,POLICY_VIEW_LOCAL_INFORMATION,&hPolicy);
}

JudyL_MD10-Apr-07 8:55

JudyL_MD

10-Apr-07 8:55

JeffRoz wrote:
Interesting that on 9x the code works if the "return 1" is uncommented, and fails when it is commented?

My guess is that the compiler is optimizing the code and removing the call to the function since it is unreachable code with that return statement on the previous line.

JeffRoz wrote:
h32 = LoadLibrary(TEXT("advapi32.dll"));
if (h32)
{
pLsaOpenPolicy = (PLSAOPENPOLICY) GetProcAddress(hAdvApi32,"LsaOpenPolicy");

pLsaOpenPolicy(NULL,&ObjectAttributes,POLICY_VIEW_LOCAL_INFORMATION,&hPolicy);
}

Make sure you check the return value from GetProcAddress and you should put () around pLsaOpenPolicy when you make the actual function call. Also, remember to call FreeLibrary when you are done with all the function pointers from the library.

Judy

JeffRoz10-Apr-07 17:26

10-Apr-07 17:26

Thanks so much for your help! Smile | :)

JeffRoz16-Apr-07 5:26

16-Apr-07 5:26

Couldn't I also just use the "Delay Loaded DLLs" in Visual Studio's Linker options?

How to send update text message with only standard windows library

JudyL_MD16-Apr-07 6:05

JudyL_MD

16-Apr-07 6:05

I don'tknow - I've never used that linker switch. You'll have to give it a try and see if it works. My concern is if you use other functions in the DLL, will it try to link every function in that DLL that you may use. In other words, what will it do when it loads that DLL but doesn't find a member of the list of required functions in the DLL? The unsupported function is still going to be in the list, even with this linker option.

As I said, I've never used delayed loading and don't know the internals of how it handles the list of functions required. You're going to have to try it to see if it works.

Good luck. Let me know if it works - it would make life simpler. If it does work, check and see if you call other functions (at runtime) that are contained in the DLL, and post that info also.

Judy

theFrenchHornet9-Apr-07 12:55

Re: How to send update text message with only standard windows library

9-Apr-07 12:55

I need to add a dialog to a project that only has available the Standard Windows Library.

I am at the point where the dialog displays and the progress bar updates. I need to add changing the text in a Label.
I don't know what command to send, and how to specify the text.
The dialog is created with:

<br />
HWND hwndProgressDialog = CreateDialog(hinstance,<br />
MAKEINTRESOURCE(IDD_DIALOG_EM),<br />
GetDesktopWindow(),<br />
EMProgressRoutine);<br />

Here is the code that updates the progress bar:

<br />
hwndProgressBar = GetDlgItem(hwndProgressDialog, IDC_PROGRESS_EM);<br />
SendMessage(hwndProgressBar, PBM_SETPOS, (WPARAM)ProgressCount, 0);<br />

To update the lable text, I assume I get a handle to the Label ID in similar fashion and do another SendMessage. But, what is the comparable command to PBM_SETPOS for setting text and how to specify the text itself?

Thanks for any help.

Mark Salsbery9-Apr-07 16:38

Mark Salsbery

9-Apr-07 16:38

You can use the SetWindowText() API (or use a WM_SETTEXT message directly) to set a control's text.

Mark

"If you can dodge a wrench, you can dodge a ball."

Re: How to send update text message with only standard windows library

theFrenchHornet10-Apr-07 4:27

Re: How to send update text message with only standard windows library

10-Apr-07 4:27

Thank you, Mark. SetWindowText works. Can you tell me, if I used the WM_SETTEXT in a SendMessage, how would I specify the text?

theFrenchHornet10-Apr-07 4:45

Re: How to send update text message with only standard windows library

10-Apr-07 4:45

Never mind. Figured it out.

prasad_som9-Apr-07 18:36

prasad_som

9-Apr-07 18:36

theFrenchHornet wrote:
hwndProgressBar = GetDlgItem(hwndProgressDialog, IDC_PROGRESS_EM);
SendMessage(hwndProgressBar, PBM_SETPOS, (WPARAM)ProgressCount, 0);

Mark Salsbery has already suggested you the right answer. I just wanted to suggest that, in case sending message to dialog items, you can use API SendDlgItemMessage. Your code will be reduce like this,

SendDlgItemMessage(hwndProgressDialog,IDC_PROGRESS_EM,PBM_SETPOS, (WPARAM)ProgressCount, 0);

Prasad
MS MVP - VC++

Re: How to send update text message with only standard windows library

theFrenchHornet10-Apr-07 4:46

Need help on game creation

10-Apr-07 4:46

Thank you, Prasad. Your method looks more intuitive.

thesad9-Apr-07 10:15

thesad

9-Apr-07 10:15

I had created game using Form, and 2 arrays of pictureboxes. I make everything, but it go very slow, so I asked my theacher how can it make faster, he said what it some function, that make project of game faster, but he didn't know hier names. So I tried search in msdn but fuond nothig. Can anybody help with this functions ?

I using visual studio c++.

David Crow9-Apr-07 10:52

David Crow

9-Apr-07 10:52

thesad wrote:
...some function, that make project of game faster...

You mean there's a magical function that we can call that will automatically make our code faster? Cool!

"Approved Workmen Are Not Ashamed" - 2 Timothy 2:15

"Judge not by the eye but by the heart." - Native American Proverb

Rick York9-Apr-07 15:58

Rick York

9-Apr-07 15:58

I suspect that would be the undocumented RunFaster( double howMuch ) function. Roll eyes | :rolleyes:

Rajesh R Subramanian9-Apr-07 20:00

Rajesh R Subramanian

9-Apr-07 20:00

thesad wrote:
so I asked my theacher how can it make faster, he said what it some function

Time to whack the teacher. Hmmm | :|

Nobody can give you wiser advice than yourself. - Cicero
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