From: ludo@gnu.org (Ludovic Courtès)
To: YOANN P <yoann_mac_donald@hotmail.com>
Cc: "30768@debbugs.gnu.org" <30768@debbugs.gnu.org>
Subject: bug#30768: Gettext : test-copy-file-1.sh fail if --with-store-dir=/var/tmp/xxxxx/gnu/store
Date: Mon, 12 Mar 2018 22:08:48 +0100 [thread overview]
Message-ID: <87vae1knmn.fsf@gnu.org> (raw)
In-Reply-To: <DB6P18901MB00224E575775984DC00D833CDBD30@DB6P18901MB0022.EURP189.PROD.OUTLOOK.COM> (YOANN P.'s message of "Mon, 12 Mar 2018 19:18:24 +0000")
Hi Yoann,
YOANN P <yoann_mac_donald@hotmail.com> skribis:
>> We won’t apply this patch because in general there’s no reason for build
>> processes to require /var/tmp (we’ve never encountered that.)
>
> There's always a first time. Since i didn't encounter this behavior with other
> custom directories than i've tested, looking at the code of the test who failed,
> i suppose than the store dir is mounted inside the build chroot as itself and is
> the reason why "/var/tmp" exist during the build with a store dir starting by
> "/var/tmp".
>
> Despite the fact that generally there’s no reason for build processes to require
> /var/tmp, is there any risk to add it to the chroot dirs ? If yes (or didn't want to
> add it), maybe a warning about the fact than we should never use a directory
> inside "/var/tmp" as store should maybe be add (it will had saving me many
> hours banging my head) because i've never read somewhere that there was
> some forbidden directories to use as store and it seems there is some
> regarding the bug i encounter.
In general we’re very cautious about changing what goes into the build
environment. The daemon provides isolated build environments, and
things will behave differently if we start adding/removing directories
or files; even simple changes like this can easily hinder
reproducibility.
>> That said, are you sure you want to use
>> --with-store-dir=/var/tmp/xxxxx/gnu/store?
>
> Yeah, i'm pretty sure i did want to use this kind of path even if it sounds
> weird or the reasons are not good. The purpose of my tests was to
> configure the store with a symlink /var/tmp/guix-[short-hash] who is
> pointing to a directory where i have the rights. This way, i could use
> my environment with user X on server A or user Y on server B only by
> adapting my symlink.
>
> This way, i could achieve a unprivileged portable environment because
> /var/tmp seems present and writable on all major distribution, plus it
> seems to work even if /var/tmp is mount with noexec.
OK, I see. That’s a worthy goal and a neat hack (I don’t think it’s
been tried before.)
>> You probably got a ‘configure’ warning already that certain things may
>> not work, for instance that the shebang max length may be exceeded.
>
> Regarding the warning , i just checked my ./configure log, and there is
> no warning about the limit length for the store path due to the limit of
> shebang length, only a warning regarding the substitutes.
>
> Even if i was aware of it after reading Pjotrp notes, i've never found a
> clear limit after my readings on the web. If Guix Team has an idea of
> the store path limit lenght, it could be a great idea to add it to the docs
> or did i missed it ?
From m4/guix.m4:
--8<---------------cut here---------------start------------->8---
dnl 'BINPRM_BUF_SIZE' constant in Linux (we leave room for the trailing zero.)
dnl The Hurd has a limit of about a page (see exec/hashexec.c.)
m4_define([LINUX_HASH_BANG_LIMIT], 127)
dnl Hardcoded 'sun_path' length in <sys/un.h>.
m4_define([SOCKET_FILE_NAME_LIMIT], 108)
--8<---------------cut here---------------end--------------->8---
>> Also using a store other than /gnu/store means you won’t be able to use
>> substitutes, nor to compare build results with other machines.
>
> I'm pretty aware of that, but having a portable environment who could be
> used even under unprivileged user without the needing of "proot" /
> "usernamespace" come with some trade offs and is just a proof of concept
> even if it is require to build all packages from scratch.
Understood.
Are you in a situation where user namespaces are unavailable? HPC?
Thanks,
Ludo’.
next prev parent reply other threads:[~2018-03-12 21:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-11 16:08 bug#30768: Gettext : test-copy-file-1.sh fail if --with-store-dir=/var/tmp/xxxxx/gnu/store YOANN P
2018-03-11 20:01 ` YOANN P
2018-03-12 13:47 ` Ludovic Courtès
2018-03-12 19:18 ` YOANN P
2018-03-12 21:08 ` Ludovic Courtès [this message]
2018-03-13 23:48 ` YOANN P
2018-03-14 9:33 ` Ludovic Courtès
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