EnumProcesses - weird behaviour - c++

Question

I have some weird behaviour while using WIndows API function EnumProcesses()
I have a function to determine wether a process with a certain name is already running which delivery different results wether I open the .executable manually (doubleclick) or open it via shell.
When I open it via shell it detects its running only 1 time (itself) and all is fine. When I open it using doubleclick on the .exe file however the function is returning true (already running) because the loop lists me the same process twice.
For the following code-snipped it is to mention that:
this->thisExecutableFile
contains argv[0] (initialised from running the program) to get the own process-name as you can see here:
int main(int argc, char* argv[])
{
ClientUpdate* update = ClientUpdate::getInstance();
update->setThisExecutableFile(argv[0]);
if (update->clientUpdateProcessIsRunning() == false) {
...
My goal is to find out if another instance of this process is already running and in this case exit it.
Here is my code:
bool ClientUpdate::clientUpdateProcessIsRunning()
{
bool retVal = false;
uint16_t processCount = 0;
unsigned long aProcesses[1024], cbNeeded, cProcesses;
if(!EnumProcesses(aProcesses, sizeof(aProcesses), &cbNeeded))
return false;
cProcesses = cbNeeded / sizeof(unsigned long);
for(unsigned int i = 0; i < cProcesses; i++) {
if (aProcesses[i] == 0) {
continue;
}
HANDLE hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, 0, aProcesses[i]);
wchar_t buffer[50];
GetModuleBaseNameW(hProcess, 0, buffer, 50);
CloseHandle(hProcess);
std::wstring tempBuffer(buffer);
std::string tempStringBuffer(tempBuffer.begin(), tempBuffer.end());
boost::filesystem::path p(this->thisExecutableFile);
if(_strcmpi(p.filename().string().c_str(), tempStringBuffer.c_str()) == 0) {
processCount++;
if(processCount > 1) {
retVal = true;
break;
}
}
}
return retVal;
}
I know that the base-path is different when using doubleclick on the file or calling it via shell. (shell produces only filename while doubleclick passes entire path + filename into argv[0]) but I fixed that issue using
boost::filesystem::path p(this->thisExecutableFile);
p.fileName()
Which returns the correct filename (without path) in both cases I checked using print.
I am pretty puzzled why EnumProcesses() returns me the same file twice when calling the file via doubleclick instead of shell. Its not spawning two processed and in taskmanager I dont see anything like this either.
Is this a bug or I need to know something about the method I couldnt find in docs?

Answer 1

Thanks to the hint by Richard Critten I was able to fix it. My method is much smaller now and easier. (Also probably also alot more performant then scanning entire process-stack.) :D
Here is the solution
bool ClientUpdate::clientUpdateProcessIsRunning()
{
HANDLE hMutex = CreateMutexA(NULL, TRUE, "client-updater-mtx");
DWORD dwErr = GetLastError();
return dwErr == ERROR_ALREADY_EXISTS;
}
Thanks!