From: "Ludovic Courtès" <ludo@gnu.org>
To: Maxime Devos <maximedevos@telenet.be>
Cc: Felix Lechner <felix.lechner@gmail.com>,
Guix Devel <guix-devel@gnu.org>
Subject: Re: A corner case of broken reproducibility
Date: Thu, 02 Jun 2022 16:08:52 +0200 [thread overview]
Message-ID: <87o7zbnonf.fsf@gnu.org> (raw)
In-Reply-To: <6b761f22d333b0acd21f407a9f5f529aaa8b16d5.camel@telenet.be> (Maxime Devos's message of "Wed, 01 Jun 2022 22:09:11 +0200")
Maxime Devos <maximedevos@telenet.be> skribis:
> Ludovic Courtès schreef op wo 01-06-2022 om 18:38 [+0200]:
>> There’s a talk by Lennart Poettering where he explains that, contrary to
>> what one might think, “chown -R $HOME” turns out to be fast enough that
>> systemd-homed can do that unconditionally (off the of my head).
>
> Interesting.
‘%gdm-activation’ has an optimization to recurse only if the top-level
directory has itself the wrong UID:
--8<---------------cut here---------------start------------->8---
(define %gdm-activation
;; Ensure /var/lib/gdm is owned by the "gdm" user. This is normally the
;; case but could be wrong if the "gdm" user was created, then removed, and
;; then recreated under a different UID/GID: <https://bugs.gnu.org/37423>.
(with-imported-modules '((guix build utils))
#~(begin
(use-modules (guix build utils))
(let* ((gdm (getpwnam "gdm"))
(uid (passwd:uid gdm))
(gid (passwd:gid gdm))
(st (stat "/var/lib/gdm" #f)))
;; Recurse into /var/lib/gdm only if it has wrong ownership.
(when (and st
(or (not (= uid (stat:uid st)))
(not (= gid (stat:gid st)))))
(for-each (lambda (file)
(chown file uid gid))
(find-files "/var/lib/gdm"
#:directories? #t)))))))
--8<---------------cut here---------------end--------------->8---
We can use that trick if needed: we’d get only one stat(2) call in the
common case.
Ludo’.
prev parent reply other threads:[~2022-06-02 14:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-25 6:10 A corner case of broken reproducibility Blake Shaw
2022-05-25 11:35 ` Felix Lechner
2022-05-30 15:58 ` Ludovic Courtès
2022-05-30 20:50 ` Maxime Devos
2022-06-01 16:38 ` Ludovic Courtès
2022-06-01 19:59 ` Maxime Devos
2022-06-02 14:13 ` Ludovic Courtès
2022-06-02 14:43 ` Maxime Devos
2022-06-01 20:09 ` Maxime Devos
2022-06-01 20:41 ` raingloom
2022-06-01 21:50 ` Maxime Devos
2022-06-02 14:08 ` Ludovic Courtès [this message]
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