Re: Prevent to exec second copy of application

[Todd Fisher <toddf simosoftware com>]

In win32 you can use a shared dll. I define the following in my app dll 
and then usually have a very small
exe load that dll, checking if the dll has been loaded before running 
another instance of the app.

#ifdef GDK_WINDOWING_WIN32
                                                                                                                                                             

#pragma data_seg(".shared")
 gint32 app_inst_count = 0;
 HWND app_hwnd = 0;
#pragma data_seg()
#pragma comment(linker, "/SECTION:.shared,RWS")
                                                                                                                                                             

__declspec (dllexport)
LONG IncrementInstanceCount (void)
{
 return InterlockedExchangeAdd(&app_inst_count,1);
}
__declspec (dllexport)
LONG GetInstanceCount (void)
{
 return app_inst_count;
}
__declspec (dllexport)
LONG DecrementInstanceCount (void)
{
 return InterlockedExchangeAdd(&app_inst_count,-1);
}
__declspec (dllexport)
LONG BringSimoToTheFront ()
{
 if( app_hwnd ){
   SetForegroundWindow( app_hwnd );
   return 1;
 }
 else
   return 0;
}
#endif


jakonda jakarta wrote:

> Helo, I try to force my application to be only one on display,
> I mean if somebody do
>
> $./my-program
> OK!
> $./my-program
> There is another copy. Use it
>
> My algorithm is follow: create atom, check if it selected by somebody, if it so another copy of application is 
> running, if it not so we are alone, select atom and work.
>
> Code is follows:
> --------------------------------------------------------------------------------------------------------------
> $ cat main.cpp
> #include <gdk/gdk.h>
>
> #include <gtk/gtk.h>
> #include <cstdlib>
> #include <cstring>
>
>
> gint OnDelete(GtkWidget *widget, GdkEvent *event, gpointer data);
> gint OnDestroy(GtkWidget *widget, GdkEvent *event, gpointer data);
>
> int main(int argc, char *argv[])
> {
>  gtk_init(&argc, &argv);
>
>  
>  GtkWidget *topLevelWindow=gtk_window_new(GTK_WINDOW_TOPLEVEL);
>  
>
>  gtk_signal_connect(GTK_OBJECT(topLevelWindow), "delete_event", 
>                     GTK_SIGNAL_FUNC(OnDelete), NULL);
>  gtk_signal_connect(GTK_OBJECT(topLevelWindow), "destroy", 
>                     GTK_SIGNAL_FUNC(OnDestroy), NULL);
>  gtk_widget_show(topLevelWindow);
>  
>  GdkAtom atom=gdk_atom_intern("MY_PRIVATE_ATOM_GTK_EXAMPLE", FALSE);
>  if(gdk_selection_owner_get_for_display(gdk_display_get_default(), atom)!=NULL)
>        g_print("There is another copy\n");
>  gtk_selection_owner_set_for_display(gdk_display_get_default(),
>                                                   topLevelWindow, atom, 0);
>  
>  gtk_main();
>  g_print("Done!\n");
>  return EXIT_SUCCESS;
> }
>
> gint OnDelete(GtkWidget *widget, GdkEvent *event, gpointer data)
> {
>  return FALSE;
> }
>
> gint OnDestroy(GtkWidget *widget, GdkEvent *event, gpointer data)
> {
>  g_print("Shutting down\n");
>  gtk_main_quit();
>  return 0;
> }
> --------------------------------------------------------------------------------------------------------------
> but it didn't work, what wrong?
> May be there is another algorithm to prevent starting second copy of application in the same dipslay?
>
> With regards, Jan.
>
> PS
>  I don't want to use bonobo.
>
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