Why doesn't this code work like it should in Inno Setup?

Question

At the very beginning of the script I have these lines of code:

#define ISSI_Splash "C:\InnoSetupProject\Images\client.bmp"                    
#define ISSI_Splash_T 3                                                                         
#define ISSI_Splash_X 500                                                                       
#define ISSI_Splash_Y 220

In my [Setup] section I add the directive:

AppMutex=ABClientLaunchMutex

Then in the [Code] section I create the mutex:

[Code]
function ISSI_InitializeSetup : Boolean;
begin
  Result := True;
  CreateMutex('ABClientLaunchMutex');
end;

#define ISSI_InitializeSetup

and those 2 lines of code are at the end of the script:

#define ISSI_IncludePath "C:\ISSI" 
#include ISSI_IncludePath+"\_issi.isi"

But this does not work as one would expect. Whenever I launch the installer it immediately shows me the mutex's message that my apllication is already running, but this is not true. I haven't created my mutex in the Global namespace, so I don't need to use the Global\ prefix. If I comment those 4 #define directives at the beginning then the mutex won't work at all.
Could you please tell me what is wrong with my code so it works like that?

Answer 1

And I need to use the AppMutex if want to prevent the installer from running if my application is already installed and launched.

I think your mistake is that you are creating the mutex within the setup script itself when your application should be doing this.

I have AppMutex only once in my script:

[setup]
AppMutex=xxxyyyzzz

As the documentation states:

Use of this directive requires that you add code to your application which creates a mutex with the name you specify in this directive.

The documentation provides example. Here is how I do it with a Visual C++ MFC project:

BOOL CMeetingScheduleAssistantApp::InitInstance()
{
    CString strMutex;

    stMutex.LoadString(IDS_APP_MUTEX);

    m_hMutex = ::CreateMutex(nullptr, FALSE, strMutex);

    ...
    ...
}