mktime: improve heuristic for ca-1986 Indiana DST

(cherry picked from commit c5118dc63cf252294a54f0e436a13d63f0761e13)

backport-mktime-improve-heuristic-for-ca-1986-Indiana-DST.patch

@@ -0,0 +1,78 @@
+From 675ba1f361ea424626b48a40cfd24d113dfc1b65 Mon Sep 17 00:00:00 2001
+From: Paul Eggert <eggert@cs.ucla.edu>
+Date: Thu, 8 Sep 2022 20:08:32 -0500
+Subject: [PATCH] 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)
+---
+ time/mktime.c | 28 ++++++++++++++++++++--------
+ 1 file changed, 20 insertions(+), 8 deletions(-)
+
+diff --git a/time/mktime.c b/time/mktime.c
+index 8e78006eea..74d9bbaa5b 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;
+     }
+-- 
+2.43.5
+

glibc.spec

@@ -71,7 +71,7 @@
 ##############################################################################
 Name: 	 	glibc
 Version: 	2.34
-Release: 	155
+Release: 	156
 Summary: 	The GNU libc libraries
 License:	%{all_license}
 URL: 		http://www.gnu.org/software/glibc/
@@ -306,6 +306,7 @@ Patch214: backport-ldconfig-Fixes-for-skipping-temporary-files.patch
 Patch215: backport-elf-Properly-align-PT_LOAD-segments-BZ-28676.patch
 Patch216: backport-stdlib-fix-grouping-verification-with-multi-byte-tho.patch
 Patch217: backport-resolv-fix-non-existing-second-DNS-response-error.patch
+Patch218: backport-mktime-improve-heuristic-for-ca-1986-Indiana-DST.patch
 
 Patch9000: turn-default-value-of-x86_rep_stosb_threshold_form_2K_to_1M.patch
 Patch9001: delete-no-hard-link-to-avoid-all_language-package-to.patch 
@@ -1522,6 +1523,12 @@ fi
 %endif
 
 %changelog
+* Sat Aug 03 2024 Funda Wang <fundawang@yeah.net> - 2.34-156
+- Type:bugfix
+- ID:
+- SUG:NA
+- DESC:mktime: improve heuristic for ca-1986 Indiana DST
+
 * Sat Jul 27 2024 chengyechun <chengyechun1@huawei.com> - 2.34-155
 - Type:bugfix
 - ID: