Re: [ANNOUNCEMENT] Update: mintty 2.1.2

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Jul 27 22:44, Houder wrote:
> > On Jul 27 19:44, Thomas Wolff wrote:
> >> Am 27.07.2015 um 17:58 schrieb Houder:
> >> >Hi Thomas,
> >> >
> >> >Moving load_dwm_funcs() did the trick ...
> >> >
> >> >
> >> Thanks again for your analysis.
> >> In Control Panel ÃÂÂ Performance Information and Tools ÃÂÂ Adjust visual
> >> effects,
> >> it is only the last of the flags, ÃÂÂ Use visual styles on windows and
> >> buttons,
> >> that makes the difference; if deselected, mintty crashes if called from a
> >> console or somehow doubly isolated by
> >> (setsid mintty &).
> >>
> >> Apparently, LoadLibrary does not propagate to a forked thread;
> >
> > Forked process, I hope :)
> >
> > No, it doesn't.  Loading a library is purly process lokal on Windows.
> > Cygwin DLLs(*) have special startup code which allows to register them
> > in the process and to re-load them in the child process at fork time.
> >
> > (*) Actually, any DLL using this special entry point would work.
> >     Native Windows DLLs just don't, usually :}
> 
> Ha, Corinna, you are the expert here, of course :-)
> 
> >From MSDN I learned (LoadLibrary() ):
> 
>     "Module handles are not global or inheritable. A call to LoadLibrary by one
>      process does not produce a handle that another process can use in calling
>      GetProcAddress (as an example). The other process must make its OWN call to
>      LoadLibrary for the module before calling GetProcAddress"
> 
> Well, ok, alright, that makes sense ...
> 
> However, if pDwmIsCompositionEnabled() returns 1, which will be the case if one
> has selected 'Windows 7' i.s.o. 'Windows Basic' (Personalization),
> 
>     as an example ...
> 
> it turned out to be possible to invoke load_dwm_funcs() (i.e. LoadLibrary() )
> before the fork to a child withOUT a crash of the child !!!!!
> 
>     After all, it is Windows ?????

What if the DLL is preloaded into processes with certain settings, e.g.
by some other Windows DLL?  LoadLibrary won't indicate if the DLL has
been loaded by this call or earlier.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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