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From: "hristo at venev dot name" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/114645] New: std::chrono::current_zone ignores $TZ on
 Linux
Date: Mon, 08 Apr 2024 19:01:49 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 13.2.1
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: hristo at venev dot name
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114645

            Bug ID: 114645
           Summary: std::chrono::current_zone ignores $TZ on Linux
           Product: gcc
           Version: 13.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hristo at venev dot name
  Target Milestone: ---

On all platforms, glibc first checks $TZ, and only defaults to `/etc/localt=
ime`
if it isn't set. Empty $TZ means UTC. One starting `:` is removed.

glibc interprets $TZ as a path, which is resolved relative to
${TZDIR:-default_tzdir}.

(if __libc_enable_secure is set, some checks are made to $TZ to prevent rea=
ding
of arbitrary files. In particular, it must not contain "../", and if absolu=
te,
must either be "/etc/localtime" or must start with the default $TZDIR)

Some more details:

https://sourceware.org/git/?p=3Dglibc.git;a=3Dblob;f=3Dtime/tzset.c;hb=3Dae=
7468a7b0bcf22e9cd5fcae42bb9e4f65de83ee#l365

https://sourceware.org/git/?p=3Dglibc.git;a=3Dblob;f=3Dtime/tzfile.c;hb=3Da=
e7468a7b0bcf22e9cd5fcae42bb9e4f65de83ee#l105=