74 lines
3.1 KiB
Diff
74 lines
3.1 KiB
Diff
|
commit 675ba1f361ea424626b48a40cfd24d113dfc1b65
|
||
|
|
Author: Paul Eggert <eggert@cs.ucla.edu>
|
||
|
|
Date: Thu Sep 8 20:08:32 2022 -0500
|
||
|
|
|
||
|
|
mktime: improve heuristic for ca-1986 Indiana DST
|
||
|
|
|
||
|
|
This patch syncs mktime.c from Gnulib, fixing a
|
||
|
|
problem reported by Mark Krenz <https://bugs.gnu.org/48085>,
|
||
|
|
and it should fix BZ#29035 too.
|
||
|
|
* time/mktime.c (__mktime_internal): Be more generous about
|
||
|
|
accepting arguments with the wrong value of tm_isdst, by falling
|
||
|
|
back to a one-hour DST difference if we find no nearby DST that is
|
||
|
|
unusual. This fixes a problem where "1986-04-28 00:00 EDT" was
|
||
|
|
rejected when TZ="America/Indianapolis" because the nearest DST
|
||
|
|
timestamp occurred in 1970, a temporal distance too great for the
|
||
|
|
old heuristic. This also also narrows the search a bit, which
|
||
|
|
is a minor performance win.
|
||
|
|
|
||
|
|
(cherry picked from commit 83859e1115269cf56d21669361d4ddbe2687831c)
|
||
|
|
|
||
|
|
diff --git a/time/mktime.c b/time/mktime.c
|
||
|
|
index 8e78006eea7e693b..74d9bbaa5b375723 100644
|
||
|
|
--- a/time/mktime.c
|
||
|
|
+++ b/time/mktime.c
|
||
|
|
@@ -429,8 +429,13 @@ __mktime_internal (struct tm *tp,
|
||
|
|
time with the right value, and use its UTC offset.
|
||
|
|
|
||
|
|
Heuristic: probe the adjacent timestamps in both directions,
|
||
|
|
- looking for the desired isdst. This should work for all real
|
||
|
|
- time zone histories in the tz database. */
|
||
|
|
+ looking for the desired isdst. If none is found within a
|
||
|
|
+ reasonable duration bound, assume a one-hour DST difference.
|
||
|
|
+ This should work for all real time zone histories in the tz
|
||
|
|
+ database. */
|
||
|
|
+
|
||
|
|
+ /* +1 if we wanted standard time but got DST, -1 if the reverse. */
|
||
|
|
+ int dst_difference = (isdst == 0) - (tm.tm_isdst == 0);
|
||
|
|
|
||
|
|
/* Distance between probes when looking for a DST boundary. In
|
||
|
|
tzdata2003a, the shortest period of DST is 601200 seconds
|
||
|
|
@@ -441,12 +446,14 @@ __mktime_internal (struct tm *tp,
|
||
|
|
periods when probing. */
|
||
|
|
int stride = 601200;
|
||
|
|
|
||
|
|
- /* The longest period of DST in tzdata2003a is 536454000 seconds
|
||
|
|
- (e.g., America/Jujuy starting 1946-10-01 01:00). The longest
|
||
|
|
- period of non-DST is much longer, but it makes no real sense
|
||
|
|
- to search for more than a year of non-DST, so use the DST
|
||
|
|
- max. */
|
||
|
|
- int duration_max = 536454000;
|
||
|
|
+ /* In TZDB 2021e, the longest period of DST (or of non-DST), in
|
||
|
|
+ which the DST (or adjacent DST) difference is not one hour,
|
||
|
|
+ is 457243209 seconds: e.g., America/Cambridge_Bay with leap
|
||
|
|
+ seconds, starting 1965-10-31 00:00 in a switch from
|
||
|
|
+ double-daylight time (-05) to standard time (-07), and
|
||
|
|
+ continuing to 1980-04-27 02:00 in a switch from standard time
|
||
|
|
+ (-07) to daylight time (-06). */
|
||
|
|
+ int duration_max = 457243209;
|
||
|
|
|
||
|
|
/* Search in both directions, so the maximum distance is half
|
||
|
|
the duration; add the stride to avoid off-by-1 problems. */
|
||
|
|
@@ -483,6 +490,11 @@ __mktime_internal (struct tm *tp,
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
+ /* No unusual DST offset was found nearby. Assume one-hour DST. */
|
||
|
|
+ t += 60 * 60 * dst_difference;
|
||
|
|
+ if (mktime_min <= t && t <= mktime_max && convert_time (convert, t, &tm))
|
||
|
|
+ goto offset_found;
|
||
|
|
+
|
||
|
|
__set_errno (EOVERFLOW);
|
||
|
|
return -1;
|
||
|
|
}
|