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Re: [PATCH] open: introduce O_NOSTD
From: |
Florian Weimer |
Subject: |
Re: [PATCH] open: introduce O_NOSTD |
Date: |
Fri, 28 Aug 2009 12:52:57 +0000 |
* Eric Blake:
> Your version fails to clear the cloexec bit of the final fd if the
> original caller didn't request O_CLOEXEC.
Okay, but you can fix that in a race-free manner (but I thought that
this was implied by open_safer).
> If the caller requested O_CLOEXEC, then your version takes 3, 5, or
> 7 syscalls depending on how many std fds were closed, while my
> version takes 3 syscalls regardless of how many std fds were closed.
I really don't see a way around that. You can't pick a descriptor and
hope that it's unused.
> Also, your suggestion has a definite race in that you are calling
> open() multiple times rather than cloning an existing fd after the
> first open(), such that another process could alter which file is
> visited between your first and last open().
Sure, but this is an unobservable differen.ce
--
Florian Weimer <address@hidden>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99
- [PATCH] open: introduce O_NOSTD, Eric Blake, 2009/08/25
- Re: [PATCH] open: introduce O_NOSTD, Davide Libenzi, 2009/08/25
- Re: [PATCH] open: introduce O_NOSTD, Eric Blake, 2009/08/27
- Re: [PATCH] open: introduce O_NOSTD, Florian Weimer, 2009/08/27
- Re: [PATCH] open: introduce O_NOSTD, Eric Blake, 2009/08/28
- Re: [PATCH] open: introduce O_NOSTD,
Florian Weimer <=
- Re: [PATCH] open: introduce O_NOSTD, Eric Blake, 2009/08/28
- Re: [PATCH] open: introduce O_NOSTD, Eric Blake, 2009/08/28
- Re: [PATCH] open: introduce O_NOSTD, Davide Libenzi, 2009/08/27
- Re: [PATCH] open: introduce O_NOSTD, Ulrich Drepper, 2009/08/27