Bug#1001774: tm_isdst=1 with mktime produces unexpected output
Hi,
On 2021-12-15 16:02, Daniel McDonald wrote:
> Package: glibc
> Version: 2.31
>
> Use of mktime with tm_isdst=1 results in -1 indicating an error. This appears unexpected, and cannot be replicated on OS X 11.6.1, Centos 7.9, Fedora 35, Alpine or RHEL 8. The issue was first observed on Github Actions ubuntu-latest (20.04).
>
> This issue was originally opened on the CPython bug tracker. They advised opening a bug report with both Ubuntu and Debian. The original report with CPython can be found here:
>
> https://bugs.python.org/issue44413
>
> An example C program follows at the end of the bug report, and can be compiled with “gcc bug.c -o bug”.
>
> An example of execution of the bug, and failure, within a glibc 2.31 environment can be found here:
>
> https://github.com/wasade/cpython/runs/4541212472?check_suite_focus=true#step:17:57
>
> Thank you for your time. Please let me know if additional information would be helpful. This is my first bug report to Debian. Though I reviewed the guidance docs, I apologize in advance if I overlooked something.
> -Daniel
>
> #include <time.h>
> #include <stdio.h>
>
> void do_test() {
> struct tm tm_works = { .tm_year=117,
> .tm_mon=4,
> .tm_mday=26,
> .tm_hour=15,
> .tm_min=30,
> .tm_sec=16,
> .tm_wday=4,
> .tm_yday=145,
> .tm_isdst=-1 };
In that structure, you define the DST to be unknown. It is therefore
left to mktime to decide if the current timezone was using DST or not at
that time.
> struct tm tm_fails = { .tm_year=117,
> .tm_mon=4,
> .tm_mday=26,
> .tm_hour=15,
> .tm_min=30,
> .tm_sec=16,
> .tm_wday=4,
> .tm_yday=145,
> .tm_isdst=1 };
In that test, you specify that the DST was in effect. It is true for
some timezones like America/New_York or Europe/Berlin, but it is not
true for timezones like UTC or Japan/Tokyo.
Therefore your test depends on your timezone. Could you please share
your timezone configuration?
Note that depending on the timezone I choose, I can make the test to
work or fail on both Debian and Fedora.
Regards,
Aurelien
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurelien@aurel32.net http://www.aurel32.net
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