On Jul 19 11:22, Jon TURNEY wrote: > On 18/07/2013 22:34, Corinna Vinschen wrote: > > On Jul 18 22:06, Jon TURNEY wrote: > >> On 18/07/2013 09:37, Corinna Vinschen wrote: > >>> On Jul 17 22:31, Jon TURNEY wrote: > >>>> After going around in circles on this a few times, this is what I now > >>>> think I > >>>> know: > >>>> > >>>> The proximate cause of this error is that the x86_64 libcairo2 package > >>>> appears > >>>> to be built with IPC_RMID_DEFERRED_RELEASE defined, which should only > >>>> happen > >>>> on systems which allow processes to shmat() to a shared memory segment > >>>> which > >>>> has already been marked for deletion with shmctl(IPC_RMID) (A > >>>> non-portable > >>>> Linux behaviour) > >>>> > >>>> (This behaviour can be turned on in cygwin by setting the > >>>> 'kern.ipc.shm_allow_removed' to 'yes' in /etc/cygserver.conf, so that is > >>>> also > >>>> a work around) > >>>> > >>>> Attached is the configure test extracted from cairo, which for some > >>>> reason > >>>> functions incorrectly on x86_64. > >>> > >>> I'm glad to read it's not a bug in Cygwin or Cygserver :} > >> > >> I'm a bit confused to read that you don't consider this shmtest.c behaving > >> incorrectly on x86_64 a bug in Cygwin. > > > > I totally misunderstood your mail apparently. Your mail implied to me > > that this is a build error in libcairo2, not in Cygwin, so I thought > > Cygwin is off the hook. > > Sorry, I should have explained more clearly that a SHM bug in cygwin could > cause an incorrect result for a configure test in cairo, which causes cairo to > be built wrongly, which causes applications which use it to fail with SHM > errors.
No worries, after you clarified, pieces fell into place :) > > Thanks for tracking this down and the patch. I'm just wondering. This > > is one of those subtil bugs introduced by the size difference between > > int and pointers. Maybe we should better provide a constructor which > > takes an ssize_t as input, rather than an int. Does the below fix the > > problem as well? > > Oh yes, that works, and is a bit clearer. Thanks for testing. I applied the patch and attributed it to you in the ChangeLog since you did all the work anyway. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
