On Mon, Oct 08, 2012 at 11:21:58PM +0100, Al Viro wrote:
> On Mon, Oct 08, 2012 at 10:53:25PM +0100, Richard W.M. Jones wrote:
> > On Mon, Oct 08, 2012 at 10:50:30PM +0100, Richard W.M. Jones wrote:
> > [.. discussion on gnulib test-cloexec test snipped ..]
> > > I'm suspicious this is a kernel bug:
> > >
> > > creat("test-cloexec.tmp", 0600) = 3
> > > fcntl(3, F_GETFD) = 0
> > > fcntl(3, F_GETFD) = 0
> > > fcntl(3, F_SETFD, FD_CLOEXEC) = 0
> > > fcntl(3, F_GETFD) = 0x1 (flags FD_CLOEXEC)
> > > fcntl(3, F_GETFD) = 0x1 (flags FD_CLOEXEC)
> > > fcntl(3, F_SETFD, 0) = 0
> > > fcntl(3, F_GETFD) = 0
> > > fcntl(3, F_DUPFD_CLOEXEC, 0) = 4
> > > fcntl(4, F_GETFD) = 0
> > > write(2, "test-cloexec.c:97: assertion failed\n", 36) = 36
> > >
> > > It seems to me from the description in the man page that
> > > F_DUPFD_CLOEXEC ought to be setting the FD_CLOEXEC flag on file
> > > descriptor 4, so either it's not or else F_GETFD isn't reading the
> > > flag for some reason.
>
> Interesting... Oh, crap. OK, that's easily fixed: in fs/fcntl.c
> err = f_dupfd(arg, filp, FD_CLOEXEC);
> should get s/FD_/O_/. Linus, could you apply the following?
>
> Fix a braino in F_DUPFD_CLOEXEC; f_dupfd() expects flags for
> alloc_fd()/get_unused_fd()/etc. and there clone-on-exec if
> O_CLOEXEC, not FD_CLOEXEC.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
I can confirm that this patch fixed the problem for me.
Tested-by: Richard W.M. Jones <rjones@xxxxxxxxxx>
> ---
> diff --git a/fs/fcntl.c b/fs/fcntl.c
> index 8f70429..71a600a 100644
> --- a/fs/fcntl.c
> +++ b/fs/fcntl.c
> @@ -258,7 +258,7 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
> err = f_dupfd(arg, filp, 0);
> break;
> case F_DUPFD_CLOEXEC:
> - err = f_dupfd(arg, filp, FD_CLOEXEC);
> + err = f_dupfd(arg, filp, O_CLOEXEC);
> break;
> case F_GETFD:
> err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
Rich.
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