CreateToolhelp32Snapshot fails under Win2000

[UdoScheuvens]

I have a problem with a function that works good under Windows 95/98. The documentation says that it also should work under Windows 2000, but when I try I get errors. First of all the code:

long lErr;
HANDLE lSnapshot1, lSnapshot2;
char sBuffer[200];
PROCESSENTRY32 ulpPE32;
BOOL bResult;

lSnapshot1 = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

ulpPE32.dwSize = sizeof(ulpPE32);
bResult = Process32First(lSnapshot1, &ulpPE32);
lErr = GetLastError();
if (lErr == ERROR_NO_MORE_FILES)
{
	MessageBox (NULL, "No processes!", NULL, MB_OK);
	return;
}


while (bResult == TRUE)
{
	lSnapshot2 = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, ulpPE32.th32ProcessID);
	if (lSnapshot2 == (HANDLE)-1)
	{
		lErr = GetLastError();
		wsprintf (sBuffer, &quot;Failed for >%s< %ld:  %ld&quot;, ulpPE32.szExeFile, ulpPE32.th32ProcessID, lErr);
		MessageBox (NULL, sBuffer, NULL, MB_OK);
	}
	else
	{
		wsprintf (sBuffer, &quot;Worked for >%s< %ld&quot;, ulpPE32.szExeFile, ulpPE32.th32ProcessID);
		MessageBox (NULL, sBuffer, NULL, MB_OK);
		CloseHandle(lSnapshot2);
	}

    bResult = Process32Next(lSnapshot1, &ulpPE32);
    lErr = GetLastError();
    if (lErr == ERROR_NO_MORE_FILES)
	{
		MessageBox (NULL, &quot;That's it!&quot;, NULL, MB_OK);
		bResult = FALSE;
	}
}

Now the results:
Under Windows 95 this code works fine. All processes give the message "Worked...". The ID is 6 or 7 digit negative number.

Under Windows 2000 the first call also works fine. But within the "while"-loop all calls fail (message "Failed...)
The error code returned by GetLastError is 5 (ERROR_ACCESS_DENIED). The ID is a 3 digit positive number.

What has to be done to make this code work under Windows 2000?

Udo

 

[PhilMunro]

Hi Udo

Sorry for the late reply. Getting process information from a Win9x machine and an NT/2000 machine is completely different, making it a real pain (especially if you're not sure what the target machine's running).

See "HOWTO: Enumerate Applications in Win32" in MSDN. There's an excellent article plus a complete code listing showing the differences between obtaining process information under 95/98 and NT/2000. What you might have trouble finding is the psapi.h header file (because I certainly did!). If you can't find it, email me and I'll send you a copy. I know the psapi.dll wasn't standard on NT (it shipped with one of the service packs) but I assume it comes with 2000 as standard, although I always install the latest version with my stuff just to be sure.

Phil
(phil.munro@shlgroup.com)

 

[Guest_imported]

Try to log on win2000 as administrator. This will give u the right to access the process info.