From 4a120c2e2e0a26e1cd5ce7cb4ebe906ef6d588d3 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?= <lrn1986@gmail.com>
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 ef67ec50b..0de5c92a3 100644
--- a/glib/gtimezone.c
+++ b/glib/gtimezone.c
@@ -871,7 +871,11 @@ 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);
-- 
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