How to check if a win32 exe file is already running? (use win32 API code)

Question

I want to check if a win32 EXE file is already running (only knowing the file path and name).

Please tell me how to realize it with win32 API code.

Thanks a lot!

I mean to have each EXE path only running one instance.

the win32 exe file being checked can be any file, despite whether it has a window or not. — , Oct 01 '19 at 04:30

score 3 · Accepted Answer · answered Oct 01 '19 at 04:37

Given only a path to the EXE, you will need to enumerate the running processes until you find one with a matching path. Look at EnumProcesses() or Process32First()/Process32Next() for that. See Process Enumeration on MSDN for more details and code examples.

score 0 · Answer 2 · answered Oct 01 '19 at 05:30

0

By reading Remy Lebeau's answer I succeed to check if the current application is already running in other processes with the following code:

DWORD processes[4096];
DWORD bytesGot;
EnumProcesses(processes, sizeof processes, &bytesGot);
DWORD processesCount = bytesGot / sizeof(DWORD);

WCHAR currName[MAX_PATH];
GetModuleFileNameEx(GetCurrentProcess(), NULL, currName, MAX_PATH);
DWORD currProcessId = GetCurrentProcessId();

for(int x=0;x<=processesCount-1;x++)
{
    HANDLE process = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, processes[x]);
    WCHAR name[MAX_PATH];
    GetModuleFileNameEx(process,NULL, name, MAX_PATH);
    CloseHandle(process);
    if (processes[x]!=currProcessId&& wcscmp(name, currName)==0) return 0;
}

Thanks to Remy Lebeau a lot :) Great useful hints.

answered Oct 01 '19 at 05:30

This sort of code I wrote is to prevent one EXE file from running two or more processes. – Oct 01 '19 at 05:42
4

That's the wrong solution to that problem. Use a named murex to do that. Also this code has no error checking. – David Heffernan Oct 01 '19 at 06:15
@David Heffernan how is that wrong? – Oct 01 '19 at 06:24
1

Well, it's subject to a race. Perfectly possible for two instances of the process to start. The way to solve your problem is to use a named mutex. There are many examples here and in other places. If only you'd asked about your problem rather than your solution. – David Heffernan Oct 01 '19 at 07:00
Also trivially defeated by changing the executable file name. – David Heffernan Oct 01 '19 at 07:01
Perhaps I didn't make it clear. I mean to have _**each EXE file path**_ running only one instance, not that to have _**this product**_ running only one instance. Therefore, this code solves it well for me. – Oct 02 '19 at 00:54
So the user just creates a copy of the exe file and hey presto, that one program be run run twice. – David Heffernan Oct 02 '19 at 05:26
@David Heffernan Yes – Oct 02 '19 at 05:50

score -3 · Answer 3 · answered Oct 01 '19 at 04:28

-3

create a blank file on startup and check the file exist.

answered Oct 01 '19 at 04:28

yumetodo

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1

This solution is bad because you have no guarantee that someone will not manually delete the file. If so, you'll consider that the _.exe_ is not running despite it still is. Wasn't me that has downvoted though. – Fareanor Oct 07 '19 at 11:40

How to check if a win32 exe file is already running? (use win32 API code)

3 Answers3