From 3a0e77449c3b2b0a48e01108ebc1dcd8add8884e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=D0=A0=D1=83=D1=81=D0=BB=D0=B0=D0=BD=20=D0=98=D0=B6=D0=B1?= =?UTF-8?q?=D1=83=D0=BB=D0=B0=D1=82=D0=BE=D0=B2?= Date: Mon, 5 Oct 2020 17:07:29 +0000 Subject: [PATCH 1/2] Add a test for the 6-days-until-EOM bug --- glib/tests/gdatetime.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/glib/tests/gdatetime.c b/glib/tests/gdatetime.c index e0541877c..4ea0fc6f4 100644 --- a/glib/tests/gdatetime.c +++ b/glib/tests/gdatetime.c @@ -2192,6 +2192,43 @@ test_z (void) g_time_zone_unref (tz); } +static void +test_6_days_until_end_of_the_month (void) +{ + GTimeZone *tz; + GDateTime *dt; + gchar *p; + + g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/2215"); + +#ifdef G_OS_UNIX + /* This is the footertz string from `Europe/Paris` from tzdata 2020b. It’s + * used by GLib when the tzdata file was compiled with `zic -b slim`, which is + * the default in tzcode ≥2020b. + * + * The `M10.5.0` part indicates that the summer time end transition happens on + * the Sunday (`0`) in the last week (`5`) of October (`10`). That’s 6 days + * before the end of the month, and hence was triggering issue #2215. + * + * References: + * - https://tools.ietf.org/id/draft-murchison-tzdist-tzif-15.html#rfc.section.3.3 + * - https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03 + */ + tz = g_time_zone_new ("CET-1CEST,M3.5.0,M10.5.0/3"); +#elif defined (G_OS_WIN32) + tz = g_time_zone_new ("Romance Standard Time"); +#endif + dt = g_date_time_new (tz, 2020, 10, 5, 1, 1, 1); + + p = g_date_time_format (dt, "%Y-%m-%d %H:%M:%S%z"); + /* Incorrect output is "2020-10-05 01:01:01+0100" */ + g_assert_cmpstr (p, ==, "2020-10-05 01:01:01+0200"); + g_free (p); + + g_date_time_unref (dt); + g_time_zone_unref (tz); +} + static void test_format_iso8601 (void) { @@ -2836,6 +2873,7 @@ main (gint argc, g_test_add_func ("/GDateTime/new_from_iso8601/2", test_GDateTime_new_from_iso8601_2); g_test_add_func ("/GDateTime/new_full", test_GDateTime_new_full); g_test_add_func ("/GDateTime/now", test_GDateTime_now); + g_test_add_func ("/GDateTime/test-6-days-until-end-of-the-month", test_6_days_until_end_of_the_month); g_test_add_func ("/GDateTime/printf", test_GDateTime_printf); g_test_add_func ("/GDateTime/non_utf8_printf", test_non_utf8_printf); g_test_add_func ("/GDateTime/format_unrepresentable", test_format_unrepresentable); From 807e4fdcdb319e9e9db9a7972fdd2e09ca41a54b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=D0=A0=D1=83=D1=81=D0=BB=D0=B0=D0=BD=20=D0=98=D0=B6=D0=B1?= =?UTF-8?q?=D1=83=D0=BB=D0=B0=D1=82=D0=BE=D0=B2?= Date: Mon, 5 Oct 2020 16:53:47 +0000 Subject: [PATCH 2/2] Fix the 6-days-until-the-end-of-the-month bug The addition causes the date to shift forward into 1st of the next month, because a 0-based offset is compared to be "more than" the days in the month instead of "more than or equal to". This is triggered by corner-cases where transition date is 6 days off the end of the month and our calculations put it at N+1th day of the month (where N is the number of days in the month). The subtraction should be triggered to move the date back a week, putting it 6 days off the end; for example, October 25 for CET DST transition; but due to incorrect comparison the date isn't shifted back, we add 31 days to October 1st and end up at November 1st). Fixes issue #2215. --- glib/gtimezone.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/glib/gtimezone.c b/glib/gtimezone.c index 3c555dbc7..96510138e 100644 --- a/glib/gtimezone.c +++ b/glib/gtimezone.c @@ -1042,7 +1042,11 @@ find_relative_date (TimeZoneDate *buffer) /* week is 1 <= w <= 5, we need 0-based */ days = 7 * (buffer->week - 1) + wday - first_wday; - while (days > days_in_month) + /* "days" is a 0-based offset from the 1st of the month. + * Adding days == days_in_month would bring us into the next month, + * hence the ">=" instead of just ">". + */ + while (days >= days_in_month) days -= 7; g_date_add_days (&date, days);