From: Rich Felker <dalias@libc.org>
To: Markus Wichmann <nullplan@gmx.net>
Cc: musl@lists.openwall.com
Subject: Re: [musl] Feasibility of FD_CLOEXEC on all streams
Date: Sat, 18 Dec 2021 12:26:46 -0500 [thread overview]
Message-ID: <20211218172646.GP7074@brightrain.aerifal.cx> (raw)
In-Reply-To: <20211218171414.GO7074@brightrain.aerifal.cx>
On Sat, Dec 18, 2021 at 12:14:15PM -0500, Rich Felker wrote:
> On Sat, Dec 18, 2021 at 05:33:20PM +0100, Markus Wichmann wrote:
> > Hi all,
> >
> > I was recently reading the source code of popen(), and noticed that it
> > has to iterate over all open files to close all the open pipe FDs the
> > child might inherit. And that made me wonder:
> >
> > 1. Does POSIX allow for all FILE streams to have FD_CLOEXEC applied by
> > default?
>
> No. Accessing fileno(f) is permissible subject to following the rules
> for active handle:
>
> https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_05_01
>
> and that entails being able to use them according to the rules for how
> fds are inherited across exec.
Also, the POSIX spec for fopen is rather explicit:
"[CX] The file descriptor associated with the opened stream shall
be allocated and opened as if by a call to open() with the
following flags: ..."
https://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html
Rich
next prev parent reply other threads:[~2021-12-18 17:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-18 16:33 Markus Wichmann
2021-12-18 17:14 ` Rich Felker
2021-12-18 17:26 ` Rich Felker [this message]
2021-12-19 14:54 ` Alex Xu (Hello71)
2021-12-19 15:22 ` Rich Felker
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