Paul Eggert <eggert@cs.ucla.edu> writes:

> I took a quick look, and in the ordinary POSIXish code there's a race
> condition between the calls to pipe2 and the calls to fcntl with
> FD_CLOEXEC.  If some other thread forks and execs a process after
> pipe2 but before fcntl, that process will have access to the pipe ends
> and this could cause problems.  Instead, please call pipe2 (..,
> O_BINARY | O_CLOEXEC) so that the other process won't see the pipe
> end.  Any child process that needs to have the pipe end survive an
> exec should then call fcntl (pipe_end, F_SETFD, 0) before execing.

Thanks.  Actually, the special case of pipe2 flags was not necessary; it
was a wreck when I tried to support FD above 2 (for stderr, the flag is
cleared in child_setup).

I updated the patch and it's now much simpler.

Regards,
-- 
Daiki Ueno