On Jul 21 10:17, Christopher Faylor wrote: > On Tue, Jul 21, 2009 at 04:05:02PM +0200, Corinna Vinschen wrote: > >On Jul 21 15:58, Corinna Vinschen wrote: > >> On Jul 21 07:04, Eric Blake wrote: > >> > -----BEGIN PGP SIGNED MESSAGE----- > >> > Hash: SHA1 > >> > > >> > It seems like it would be pretty easy to add several new close-on-exec > >> > features required by POSIX 2008: > >> > > >> > open(name, O_RDONLY | O_CLOEXEC); > >> > // skips the need to use fcntl > >> > > >> > fcntl(fd, F_DUPFD_CLOEXEC); > >> > // like F_DUPFD, but closes window without having to use > >> > // fcntl(fd, F_SETFD, fcntl(fd, F_GETFD)) > >> > > >> > and those provided by glibc as extensions: > >> > > >> > fopen(name, "re"); > >> > // like fopen "r", but with cloexec set > >> > > >> > The argument is that in multi-threaded apps, if one thread opens a file > >> > but has not yet turned on the close-on-exec bit while another thread does > >> > a fork-and-exec, then you leaked the fd into the child; and these new > >> > flags close the window. > >> > > >> > Should I go ahead and prepare a patch for the newlib side? > >> > >> It's not that easy to implement, especially not the fcntl which requires > >> to redefine the dup2 methods throughout to allow atomic operation on the > >> target OS handles. open (O_CLOEXEC) is much easier. Anyway, can we > >> wait until after Cygwin 1.7.1? > > > >...which is to say, I added it to my TODO list. > > I agree about waiting, but I think this is one for my TODO list. The > close_on_exec code is all mine, AFAIK. I reworked it all back in 1998 > or so, so it is pretty fresh in my mind.
I don't think there's a lot to do in close_on_exec code itself related to this. There is no need to call set_close_on_exec at all, rather the fhandler should create the handle not inheritable in the first place. That goes for open as well as fcntl. Time to add Linux' dup3 call, I guess :) Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Project Co-Leader cygwin AT cygwin DOT com Red Hat -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
