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