Re: Cannot run Qt5 applications.

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

On Mar  2 17:34, Yaakov Selkowitz wrote:
> On Fri, 2015-02-13 at 18:32 +0000, Jon TURNEY wrote:
> > On 05/02/2015 01:40, Jon TURNEY wrote:
> > > On 04/02/2015 23:20, David Stacey wrote:
> > >> I'm having difficulty running any Qt5 application. These are the
> > >> commands I'm issuing:
> > >> [snip]
> > >> and I see the clock, so X is up and running. Then:
> > >> [snip]
> > >
> > > Possibly you need to install and start cygserver (See [1])
> > >
> > > If so, this is because Qt5 is assuming shared memory is available, which
> > > could possibly be handled in a better way...
> > 
> > This looks like a portability problem in Qt5, where it only handles 
> > shmget() failing with a return value of -1, not with SIGSYS, to fallback 
> > to using an image in unshared memory.
> > 
> > Patch attached.
> 
> Or is it a problem with our shmget()?
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/shmget.html
> http://man7.org/linux/man-pages/man2/shmget.2.html
> 
> Perhaps we should be just returning -1 with an errno (ENOSYS?) instead
> of raise(SIGSYS)?

Or you just add signal(SIGSYS, SIG_IGN) prior to calling shmget.
SIGSYS is raised when calling a system call which isn't available.
That's perfectly valid.

Of course, it would be nice if Qt5 used POSIX shared memory objects
iunstead, but that's asked too much, probably.


Corinna

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

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