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Environment: VC6 SP4, Windows 2000/NT and 95/98/Me
Abstract
Some time ago I developed a system that had to meet a common requirement for supporting Windows 9x as well as NT/2000 family. Everything went smoothly until I had to implement a mechanism for retrieving all currently running processes along with mapped to each process DLLs. Windows 9x/ME and 2000 provide a built-in implementation (i.e. implemented by Kernel32.dll) of Tool Help Library. On the other hand Windows NT uses for the same purpose PSAPI library. I needed a way to allow my application to run and then to detect dynamically which process "helper" is available. Thus the system can determine which the supported library is, and accordingly to use the appropriate APIs.
Solution
I would like to present an object-oriented architecture that implements a simple framework for retrieving processes and modules under NT/2000 and 9x/ME. The design of my classes allows extending the framework according to your specific needs. The implementation itself is pretty straightforward. CTaskManager implements the system’s processor. It is responsible for creating an instance of a specific library handler (i.e. CPsapiHandler or CToolhelpHandler) that is able to employ the correct process information provider library (i.e. PSAPI or ToolHelp32 respectively). CTaskManager is in charge of creating and marinating a container object that keeps a list with all currently active processes. After instantiating of the CTaskManager
object the application calls Populate() method. It forces enumerating of all processes and DLL libraries and storing them into a hierarchy kept by CTaskManager'smember m_pProcesses.
It is important to take into account the fact that NT’s Kernel32.dll doesn’t
implemented any of the ToolHelp32 functions. Therefore we must link them
explicitly, using runtime dynamic linking. Otherwise, if we use static linking
the code will fail to load on NT, regardless whether or not the application has attempted
to execute any of those functions.
Following snippet illustrates exposed by CTaskManager basic interface methods.
int
main(int argc, char* argv[])
{
CTaskManager taskManager;
CExeModuleInstance *pProcess;
CModuleInstance *pModule;
// Retrieves information about processes and modules.
// The taskManager dynamically decides whether to use ToolHelp library or PSAPI
taskManager.Populate();
// Enumerates all processes
for (unsigned i = 0; i < taskManager.GetProcessCount(); i++)
{
pProcess = taskManager.GetProcessByIndex(i);
printf("Process %s pid=%dn", pProcess->Get_Name(), pProcess->Get_ProcessId());
// Enumerates all modules loaded by (pProcess) process
for (unsigned j = 0; j < pProcess->GetModuleCount(); j++)
{
pModule = pProcess->GetModuleByIndex(j);
printf("t %s
Handle=%.8xn", pModule->GetBaseName(), pModule->Get_Module());
} // for
} // for
return 0;
}
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