Checking if mutex-object exists does not work in a loop

My installer does a mutex check within a loop but the problem is, that if I close the program which created this mutex first the installer still thinks it is running. But it isn't. How can I solve this?

Var loop_count



  loop:

  IntOp $loop_count $loop_count + 1

  Sleep 1000

  

  System::Call 'kernel32::CreateMutexA(i 0, i 0, t "myMutex") i .r1 ?e'

  Pop $0

  StrCmp $0 "0" +3 +1

   IntCmp $loop_count 10 +1 loop +1

    Quit

.r1 is $1 not $0.

Stu

Still doesn't work. Calling the mutex-check only once does work as it should, no matter whether the application is running or not. It's only within the loop where the mutex-check returns everytime 183, even if the application does not run anymore.

Also remove the Pop. The call to CreateMutex isn't putting anything on the stack. It's putting its return value directly into $1.

Stu

Ah, I didn't knew this, thanks. But anyway, the problem still exists and now I think I know why. The System-plugin calls GetLastError (and this call will write to the stack) but If I call CreateMutexA several times, the system still returns the "last" error, even if the last call was successful. Would be that possible?

I tried resetting the last error with System::Call 'kernel32::SetLastError(i 0)' but it didn't work. If I called GetLastError after the Set-call the returned code was 80 even if I didn't called SetLastError.

Do you have any idea what is happening there? Or anybody else?

Why are you not using OpenMutex?

Also, don't mix dll::FunctionnameA with t type, either use Functionname and t, or FunctionnameA and m

Because I didn't knew it so far. After I googled for OpenMutex I found this page and the solution.

Combined with "kernel32::OpenMutex", "kernel32::CloseHandle" did the trick and my loop is perfectly working now. Thank you very much Anders! 😁