Subject: bug#59321: ice-9's open-input-pipe is unexpectedly slow on some systems

From: <[email-masked]>
Date: Sun, 20 Nov 2022 20:00:34 +0100

On Sun, Nov 20, 2022 at 06:24:57PM +0100, Ludovic Courtès wrote:
> Hi,
> 
> Andrew Whatson <[email-masked]> skribis:
> 
> > Forcibly closing file descriptors like this shouldn't be necessary if
> > the application has properly opened descriptors with the FD_CLOEXEC
> > flag.  It would be good to get input from some more experienced Guile
> > hackers on the potential consequences of this change.
> 
> Libguile opens all its own file descriptors at O_CLOEXEC (one omission
> was recently fixed in 0aa1a9976fc3c6af4d1087e59d728cb8fe7d369a) so it
> may be possible to remove that FD-closing loop.  There’s still the
> possibility that application bug unwillingly leaks FDs, but we could
> consider it’s none of our business.
> 
> Thoughts?

Hm. Socket FDs don't "have" O_CLOEXEC. Arguably, they are at least as
"interesting" as file FDs (meaning: source of obscure bugs).

Moreover, misbehaving C libraries can be an additional source of bugs
we have no control of.

The reference I posted upthread makes a compelling case for at least
needing an option for this (admittedly ugly) close orgy (perhaps with
some additional platform-dependent mitigations, but that's an ugliness
in its own, sigh).

Cheers
-- 
t