No NONBLOCK flag for dup3() or epoll_create1()?

[Michael Kerrisk <mtk.manpages@googlemail.com>]

Ulrich

I've been doing some testing (2.6.27-rc3) of your new
file-descriptor-creating syscalls that accept flags.  According to

http://udrepper.livejournal.com/20407.html

all of the system calls should accept a *_NONBLOCK flag.  All of them do,
except for two:
dup3(olfd, newfd, flags)
and
epoll_create1(flags).

For epoll_create1() this certainly appears to be an oversight, since I can't
think of a reason not to support *_NONBLOCK.

For dup3() it is perhaps also an oversight.  However, it's not really clear
to me whether supporting O_NONBLOCK makes sense, since that would change the
file status flags of the open file description that is (also) referred to by
oldfd.  (Furthermore, given a open file description for which O_NONBLOCK is
already enabled, it is not possible to make a dup3() call that disables
O_NONBLOCK, which is an odd asymmetry in the API.)  What are your thoughts on
this?

Cheers,

Michael