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SubjectRe: FD_CLFORK or equivalent?
On May 05, Richard B. Johnson wrote:

> On Wed, 5 May 1999, Bernd Eckenfels wrote:
>
> > In article <Pine.QNX.3.96.990504112943.30630A-100000@sam.cogent.ca> you wrote:
> > > If not, before I hack one in as a private kernel patch, is
> > > there any reason to add such a mechanism, perhaps a FD_CLOFORK
> > > flag, and does anybody have suggestions on where to start?
> >
> > A reason would be, that this is a good way of making daemons. Since closing
> > all fds from 0-255 is not enough on systems where high-numberes fds can be
> > open.
> >
> But... The 'standard' way is:
>
> fd = open("/", O_RDONLY);
> while (fd >= 0) (void)close(fd--);
>

this `standard way' is broken!

main()
{
close(0);
printf("%d\n",open ("/",0));
}

will output 0 (zero) using glibc-2.0.7.
so your `standard way' won't close fds 1 and 2 after a close(0)...


Harald
--
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\ OOOOOOOOOOOOOOOOO|//
Harald Koenig, \/\/\/\/\/\/\/\/\/
Inst.f.Theoret.Astrophysik // / \\ \
koenig@tat.physik.uni-tuebingen.de ^^^^^ ^^^^^

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