Bug 938309 – Gentoo stages (incl. systemd stages) default to /etc/localtime as a file, whil sys-apps/systemd expects a symlink

• Product: Gentoo Release Media
• Status: CONFIRMED ---

[Description Michał Górny 2024-08-22 09:33:26 UTC]

According to localtime(5) (installed by systemd):

> It should be an absolute or relative symbolic link pointing to /usr/share/zoneinfo/ […]
>
> Because the timezone identifier is extracted from the symlink target name of /etc/localtime, this file may not be a normal file or hardlink.

However, in our stages (both OpenRC and systemd stages), /etc/localtime is a regular file.  And of course, since people already started assuming systemd is the golden standard, e.g. newer experimental API in libc++ throws an exception if it's not a symlink.

I think we should update it to be a symlink for the best compatibility (but I have filed a bug upstream anyway).

[Comment 1 Mike Gilbert 2024-08-22 16:59:11 UTC]

I would not expect /etc/localtime to exist at all in stage3 tarballs. I wonder what creates it.

[Comment 2 Mike Gilbert 2024-08-22 17:04:12 UTC]

Ah, it might be this hook in stage1:

https://gitweb.gentoo.org/proj/catalyst.git/tree/targets/stage1/preclean-chroot.sh

[Comment 3 Michał Górny 2024-10-09 11:18:26 UTC]

Gentle ping.

[Comment 4 Ben Kohler 2024-10-09 16:43:11 UTC]

Testing with this change now:


diff --git a/targets/stage1/preclean-chroot.sh b/targets/stage1/preclean-chroot.sh
index 2dc761e9..193a12f9 100755
--- a/targets/stage1/preclean-chroot.sh
+++ b/targets/stage1/preclean-chroot.sh
@@ -15,7 +15,7 @@ setup_binutils
 if [ -d "${ROOT}/usr/share/zoneinfo" ]
 then
        rm -f "${ROOT}/etc/localtime"
-       cp "${ROOT}/usr/share/zoneinfo/Factory" "${ROOT}/etc/localtime"
+       ln -s ../usr/share/zoneinfo/Factory "${ROOT}/etc/localtime"
 else
        echo UTC > "${ROOT}/etc/TZ"
 fi

[Comment 5 Larry the Git Cow 2024-10-10 01:07:56 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/proj/catalyst.git/commit/?id=e574dbd24c74cedd7f59263859a6551b914410a4

commit e574dbd24c74cedd7f59263859a6551b914410a4
Author:     Ben Kohler <[e-mail]>
AuthorDate: 2024-10-10 01:06:11 +0000
Commit:     Ben Kohler <[e-mail]>
CommitDate: 2024-10-10 01:06:11 +0000

    targets/stage1/preclean-chroot.sh: use symlink for /etc/localtime
    
    This should be a symlink on modern systems.
    
    Bug: https://bugs.gentoo.org/938309
    Signed-off-by: Ben Kohler <[e-mail]>

 targets/stage1/preclean-chroot.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

[Comment 6 Mike Gilbert 2024-10-18 15:48:19 UTC]

Could we update that hook to not create any file/link at all? Having a symlink to the bogus "Factory" zone is pretty useless.

If /etc/localtime does not exist, libc and timedatedtl will default to UTC, which seems reasonable.

[Comment 7 Mike Gilbert 2024-10-18 16:54:11 UTC]

I suppose we should check that new libc++ API to see how it handles /etc/localtime not existing at all.

[Comment 8 Holger Hoffstätte 2024-10-18 17:00:01 UTC]

(In reply to Mike Gilbert from comment #7)
> I suppose we should check that new libc++ API to see how it handles
> /etc/localtime not existing at all.

Make a guess :)

https://github.com/llvm/llvm-project/blob/7da0a698526ff657c2348a6e4bb835fc764177da/libcxx/src/experimental/tzdb.cpp#L727