InstallScript detect app during upgrade?

MyApp.exe is installed using an InstallScript 2014 project. The folks in manufacturing recently tried to upgrade to a more recent development version but did not close the existing instance of MyApp. This resulted in many permission denied errors since the various dll's used by the app were locked and in use.

I expected the InstallScript executable to do the usual "stage and reboot" thing that all Windows folks are intimate with. It did not do that, and I can't see anything in the InstallShield project editor that obviously lets me force that behavior.

I also expected InstallScript to allow me to somehow detect that my app was already running - if I can do that, I can display a dialog to give the user a chance to close the app and continue. The only solution for this is InstallSite.org List and Shutdown Running Processes. (Note this is unanswered on another S/O question.)

That does not properly detect all of the running tasks, including my own.

Before I spend a couple of days trying to fix what seems to be an obviously missing feature of InstallScript, I thought I'd ask if there's a better approach.

Here's what I came up with. Hope this helps.

// defines/protos for finding a process
#define TH32CS_SNAPPROCESS  0x00000002

// in Kernel32.dll
prototype NUMBER    Kernel32.CreateToolhelp32Snapshot(NUMBER , NUMBER);
prototype BOOL      Kernel32.Process32First(HWND , POINTER );
prototype BOOL      Kernel32.Process32Next(HWND , POINTER );

// from minwindef.h, windows api
typedef PROCESSENTRY32
begin
    number dwSize;
    number cntUsage;
    number th32ProcessID;          // this process
    number th32DefaultHeapID;
    number th32ModuleID;           // associated exe
    number cntThreads;
    number th32ParentProcessID;    // this process's parent process
    number pcPriClassBase;        // Base priority of process's threads
    number dwFlags;
    STRING szExeFile[MAX_PATH];     // Path
end;

// ========================================================================================
// list all of the running processes, see if Flex is running
// based on https://msdn.microsoft.com/en-us/library/windows/desktop/ms686701(v=vs.85).aspx
// ========================================================================================
function BOOL IsProcessRunning(sProcessName)
    HWND hProcessSnap;
    PROCESSENTRY32 pe;
    POINTER ppe;
    NUMBER ret;

begin
    hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

    pe.dwSize = SizeOf(pe); 
    ppe = &pe;

    ret = Process32First(hProcessSnap, ppe);

    if (ret == 0) then
      //printError(TEXT("Process32First")); // show cause of failure
      CloseHandle(hProcessSnap);          // clean the snapshot object
      return(FALSE);
    endif;

    repeat      
        if (StrCompare(sProcessName, pe.szExeFile) == 0) then
            CloseHandle(hProcessSnap);          // clean the snapshot object
            return(TRUE);
        endif;
        ret = Process32Next(hProcessSnap, ppe);
    until (ret == 0);

   return(FALSE);
end;

You then call it

if (IsProcessRunning("WORD.EXE")) then
    blah blah
endif;