tzdata-2024b-0ubuntu0.24.04 makes std::chrono unusable

[Daniel Nöh]

[ Impact ]
The latest tzdata SRU[1] included a change[2] in the main data form:

    The main source files' time zone abbreviations now use %z,
    supported by zic since release 2015f and used in vanguard form
    since release 2022b. For example, America/Sao_Paulo now contains
    the zone continuation line "-3:00 Brazil %z", which is less error
    prone than the old "-3:00 Brazil -03/-02". This does not change
    the represented data: the generated TZif files are unchanged.
    Rearguard form still avoids %z, to support obsolescent parsers.

Turns out the standard c++ library in at least oracular and noble fail to parse that, resulting in a much small list of available timezones, or even crashes[3].

The c++ fix for that is in [4]. That might be eventually SRUed, but at the moment it's quicker to adjust tzdata than the c++ library. Also, there might be other parsers in the supported Ubuntu releases that are also affected, and just haven't been noticed yet.

1. https://launchpad.net/bugs/2070285
2. https://github.com/eggert/tz/commit/94e6b3b0eb773e66a9ac49b905c69c0fa6a31dc3
3. https://bugs.launchpad.net/ubuntu/+source/tzdata/+bug/2096974/comments/10
4. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116657

[ Test Plan ]

This update includes a new DEP8 test that checks specifically for this bug. Therefore, the test plan is to observe that the full suite of autopkgtests is run and that it passed.

For jammy and focal, which do not contain the c++ library function that is failing, build this small C++ app in *NOBLE*:

#include <chrono>
#include <iostream>

int main() {
    for (const auto & time_zone : std::chrono::get_tzdb().zones) {
        std::cout << time_zone.name() << std::endl;
    }
}

Build and link statically, like so (assuming the file is called test.cpp):

  g++ -std=c++20 -o test test.cpp -static

Then copy the resulting binary ("test") to the jammy and focal systems under test.

An affected system will show just two timezones:

  $ ~/test
  Etc/GMT
  Etc/UTC

Whereas a fixed system will show hundreds.

[ Where problems could occur ]

All software that use tzdata could be affected by this update. There is probably at least one implementation in each programming language for reading the timezone data. The update could trigger parser bugs.

The autopkgtest will cover Python's zoneinfo and now C++ std::chrono.

[ Original Description ]

inalling tzdata in version 2024b-0ubuntu0.24.04 causes std::chrono to deliver only 2 timezones:

code:

for (const auto & time_zone : std::chrono::get_tzdb().zones)
{
  std::cout << time_zone.name() << std::endl;
}

output:

Etc/GMT
Etc/UTC

[Daniel Nöh (wodn)]

corresponding fix exists: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116657
but the mentioned versions are not yet available on ubuntu

[Benjamin Drung (bdrung)]

I can reproduce that behavior and distilled a test case for tzdata.

[Benjamin Drung (bdrung)]

Test results:

* plucky 2024b-6ubuntu1 is NOT affected
* oracular 2024b-1ubuntu2.1 is affected
* noble 2024b-0ubuntu0.24.04 is affected
* jammy fails to compile the example code:

error: ‘get_tzdb’ is not a member of ‘std::chrono’
    6 | for (const auto & time_zone : std::chrono::get_tzdb().zones) {
      | ^~~~~~~~

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Benjamin Drung (bdrung)]

It looks like the upstream commit https://github.com/eggert/tz/commit/94e6b3b0eb773e66a9ac49b905c69c0fa6a31dc3 is the reason for it.

As workaround switch from the main format to the rearguard format until std::chrono is fixed. The NEWS file says:

    The main source files' time zone abbreviations now use %z,
    supported by zic since release 2015f and used in vanguard form
    since release 2022b. For example, America/Sao_Paulo now contains
    the zone continuation line "-3:00 Brazil %z", which is less error
    prone than the old "-3:00 Brazil -03/-02". This does not change
    the represented data: the generated TZif files are unchanged.
    Rearguard form still avoids %z, to support obsolescent parsers.

[Benjamin Drung (bdrung)]

Proposed fix for oracular (same for noble): https://code.launchpad.net/~ubuntu-core-dev/ubuntu/+source/tzdata/+git/tzdata/+merge/480392

[Andreas Hasenack (ahasenack)]

Hello Daniel, or anyone else affected,

Accepted tzdata into oracular-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/tzdata/2024b-1ubuntu2.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-oracular to verification-done-oracular. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-oracular. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Andreas Hasenack (ahasenack)]

Hello Daniel, or anyone else affected,

Accepted tzdata into noble-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/tzdata/2024b-0ubuntu0.24.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-noble to verification-done-noble. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-noble. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Taylor Brown (tbrown122387)]

Works for me! After

wget http://archive.ubuntu.com/ubuntu/pool/main/t/tzdata/tzdata_2024b-1ubuntu2.2_all.deb
sudo dpkg -i tzdata_2024b-1ubuntu2.2_all.deb

c++ lines with

std::chrono::locate_zone("America/New_York")

no longer throw an error such as

terminate called after throwing an instance of 'std::runtime_error'
  what(): std::chrono::tzdb: cannot locate zone: America/New_York
Aborted (core dumped)

[Daniel Nöh (wodn)]

HI,

yes, the proposed version 2024b-0ubuntu0.24.04.1 works fine!

[Anders Lindstrom (anderu)]

Works for me too. Thanks.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted tzdata (2024b-1ubuntu2.2) for oracular have finished running.
The following regressions have been reported in tests triggered by the package:

python3.12/3.12.7-1ubuntu1.1 (ppc64el)
python3.13/3.13.0-1 (arm64)
python3.13/unknown (s390x)
tzdata/2024b-1ubuntu2.2 (amd64, s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/oracular/update_excuses.html#tzdata

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted tzdata (2024b-0ubuntu0.24.04.1) for noble have finished running.
The following regressions have been reported in tests triggered by the package:

astropy/6.0.0-1ubuntu2 (arm64, armhf, ppc64el, s390x)
tzdata/2024b-0ubuntu0.24.04.1 (amd64)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/noble/update_excuses.html#tzdata

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Andreas Hasenack (ahasenack)]

Thank you all! We pushed this to proposed even before having a complete test plan and SRU template, apologies for that. But there is a new autopkgtest to test exactly this behavior (thanks bdrung!). I'm trying to sort out the test failures now, I've seen already that a few were due to infrastructure failures and retried them.

[Andreas Hasenack (ahasenack)]

This is fixing a regression in the previous SRU (which is currently in updates)

[David Ainsworth (aindj)]

It's worth saying that jammy is also affected by this bug
Even though you can't compile the reproducer c++ code with the packaged version of gcc, it's still possible to either install gcc13 and compile/run it or to run a binary compiled on a different machine and trigger the issue

[Benjamin Drung (bdrung)]

The test TestTimeUT1SpecificIERSTable.test_ut1_iers_A from astropy/6.0.0-1ubuntu2 on noble seem to regress with both 2024b SRU uploads.

[Andreas Hasenack (ahasenack)]

It did pass[1] with 2024a back in 2024-05-03, so maybe it's sensitive to the date.

1. https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/ppc64el/a/astropy/20240503_141545_cef6c@/log.gz

[Andreas Hasenack (ahasenack)]

> Even though you can't compile the reproducer c++ code with the packaged version of gcc, it's still
> possible to either install gcc13 and compile/run it or to run a binary compiled on a different machine
> and trigger the issue

Indeed, and jammy/focal have tasks in this bug to be fixed as well. We are more immediately worried about noble because of the imminent 24.04.2 point release next week.

[Andreas Hasenack (ahasenack)]

Retrying the python3.12/tzdata test in oracular/ppc64el... https://autopkgtest.ubuntu.com/packages/python3.12/oracular/ppc64el

[Andreas Hasenack (ahasenack)]

The autopkgtests are all green now, for oracular and noble. Per test plan, that is the verification, and we also had confirmation in multiple comments that this update fixed the issue.

[Launchpad Janitor (janitor)]

This bug was fixed in the package tzdata - 2024b-1ubuntu2.2

---------------
tzdata (2024b-1ubuntu2.2) oracular; urgency=medium

  * Revert using %z in tzdata.zi data form (LP: #2096974):
    - Enable link to link feature also for rearguard dataform
    - Use dataform rearguard for C++ std::chrono
    - Add chrono autopkgtest to test C++ std::chrono::tzdb parser

 -- Benjamin Drung <email address hidden> Thu, 30 Jan 2025 20:42:02 +0100

[Andreas Hasenack (ahasenack)]

The verification of the Stable Release Update for tzdata has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package tzdata - 2024b-0ubuntu0.24.04.1

---------------
tzdata (2024b-0ubuntu0.24.04.1) noble; urgency=medium

  * Revert using %z in tzdata.zi data form (LP: #2096974):
    - Enable link to link feature also for rearguard dataform
    - Use dataform rearguard for C++ std::chrono
    - Add chrono autopkgtest to test C++ std::chrono::tzdb parser

 -- Benjamin Drung <email address hidden> Thu, 30 Jan 2025 22:33:14 +0100

[Andreas Hasenack (ahasenack)]

Hello Daniel, or anyone else affected,

Accepted tzdata into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/tzdata/2024b-0ubuntu0.22.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Andreas Hasenack (ahasenack)]

Hello Daniel, or anyone else affected,

Accepted tzdata into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/tzdata/2024b-0ubuntu0.20.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted tzdata (2024b-0ubuntu0.20.04.1) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

icu/66.1-2ubuntu2.1 (s390x)
postgresql-12/12.22-0ubuntu0.20.04.1 (amd64, s390x)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/focal/update_excuses.html#tzdata

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted tzdata (2024b-0ubuntu0.22.04.1) for jammy have finished running.
The following regressions have been reported in tests triggered by the package:

chrony/4.2-2ubuntu2 (armhf, ppc64el)
php8.1/8.1.2-1ubuntu2.20 (armhf)
postgresql-14/14.15-0ubuntu0.22.04.1 (armhf)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/jammy/update_excuses.html#tzdata

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Daniel Nöh (wodn)]

hi,
yes, version 2024b-0ubuntu0.20.04.1 look fine!

[Benjamin Drung (bdrung)]

The autopkgtest for 2024b-0ubuntu0.22.04.1 and 2024b-0ubuntu0.20.04.1 are successful after retrying some failed ones.

[Benjamin Drung (bdrung)]

I built the static test executable on noble and verified jammy:

```
$ schroot-wrapper -c jammy-debug -p tzdata -e
(jammy-debug)bdrung@host:~$ ./test | wc -l
446
(jammy-debug)bdrung@host:~$ dpkg -s tzdata | grep ^Version
Version: 2024b-0ubuntu0.22.04.1
```

Before:

```
$ schroot-wrapper -c jammy-debug -p tzdata
(jammy-debug)bdrung@host:~$ ./test
Etc/GMT
Etc/UTC
(jammy-debug)bdrung@host:~$ dpkg -s tzdata | grep ^Version
Version: 2024b-0ubuntu0.22.04
```

Verified focal:

```
$ schroot-wrapper -c focal-debug -p tzdata -e
(focal-debug)bdrung@host:~$ ./test | wc -l
446
(focal-debug)bdrung@host:~$ dpkg -s tzdata | grep ^Version
Version: 2024b-0ubuntu0.20.04.1
```

[Launchpad Janitor (janitor)]

This bug was fixed in the package tzdata - 2024b-0ubuntu0.22.04.1

---------------
tzdata (2024b-0ubuntu0.22.04.1) jammy; urgency=medium

  * Revert using %z in tzdata.zi data form (LP: #2096974):
    - Enable link to link feature also for rearguard dataform
    - Use dataform rearguard for C++ std::chrono

 -- Benjamin Drung <email address hidden> Fri, 31 Jan 2025 13:53:56 +0100

[Launchpad Janitor (janitor)]

This bug was fixed in the package tzdata - 2024b-0ubuntu0.20.04.1

---------------
tzdata (2024b-0ubuntu0.20.04.1) focal; urgency=medium

  * Revert using %z in tzdata.zi data form (LP: #2096974):
    - Enable link to link feature also for rearguard dataform
    - Use dataform rearguard for C++ std::chrono

 -- Benjamin Drung <email address hidden> Sat, 01 Feb 2025 13:04:09 +0100

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.