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* [glibc/release/2.36/master] time: Set daylight to 1 for matching DST/offset change (bug 29951)
@ 2023-01-10 16:03 Florian Weimer
0 siblings, 0 replies; only message in thread
From: Florian Weimer @ 2023-01-10 16:03 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e05036b194559cbfcdfcfb1b920d37b939e3e35c
commit e05036b194559cbfcdfcfb1b920d37b939e3e35c
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Jan 5 18:21:25 2023 +0100
time: Set daylight to 1 for matching DST/offset change (bug 29951)
The daylight variable is supposed to be set to 1 if DST is ever in
use for the current time zone. But __tzfile_read used to do this:
__daylight = rule_stdoff != rule_dstoff;
This check can fail to set __daylight to 1 if the DST and non-DST
offsets happen to be the same.
(cherry picked from commit 35141f304e319109c322f797ae71c0b9420ccb05)
Diff:
---
NEWS | 1 +
time/tzfile.c | 41 +++++++++++++++--------------
timezone/Makefile | 4 ++-
timezone/testdata/XT6 | Bin 0 -> 625 bytes
timezone/tst-bz29951.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 94 insertions(+), 20 deletions(-)
diff --git a/NEWS b/NEWS
index dbe2b2e301..8c79e83b77 100644
--- a/NEWS
+++ b/NEWS
@@ -51,6 +51,7 @@ The following bugs are resolved with this release:
[29730] broken y2038 support in fstatat on MIPS N64
[29771] Restore IPC_64 support in sysvipc *ctl functions
[29776] elf/tst-tlsopt-powerpc fails when compiled with -mcpu=power10
+ [29951] time: Set daylight to 1 for matching DST/offset change
\f
Version 2.36
diff --git a/time/tzfile.c b/time/tzfile.c
index 394b098856..8bba4e5b8d 100644
--- a/time/tzfile.c
+++ b/time/tzfile.c
@@ -61,6 +61,10 @@ static size_t num_leaps;
static struct leap *leaps;
static char *tzspec;
+/* Used to restore the daylight variable during time conversion, as if
+ tzset had been called. */
+static int daylight_saved;
+
#include <endian.h>
#include <byteswap.h>
@@ -438,36 +442,35 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
if (__tzname[1] == NULL)
__tzname[1] = __tzname[0];
+ daylight_saved = 0;
if (num_transitions == 0)
/* Use the first rule (which should also be the only one). */
rule_stdoff = rule_dstoff = types[0].offset;
else
{
- int stdoff_set = 0, dstoff_set = 0;
- rule_stdoff = rule_dstoff = 0;
+ rule_stdoff = 0;
+
+ /* Search for the last rule with a standard time offset. This
+ will be used for the global timezone variable. */
i = num_transitions - 1;
do
- {
- if (!stdoff_set && !types[type_idxs[i]].isdst)
- {
- stdoff_set = 1;
- rule_stdoff = types[type_idxs[i]].offset;
- }
- else if (!dstoff_set && types[type_idxs[i]].isdst)
- {
- dstoff_set = 1;
- rule_dstoff = types[type_idxs[i]].offset;
- }
- if (stdoff_set && dstoff_set)
+ if (!types[type_idxs[i]].isdst)
+ {
+ rule_stdoff = types[type_idxs[i]].offset;
break;
- }
+ }
+ else
+ daylight_saved = 1;
while (i-- > 0);
- if (!dstoff_set)
- rule_dstoff = rule_stdoff;
+ /* Keep searching to see if there is a DST rule. This
+ information will be used to set the global daylight
+ variable. */
+ while (i-- > 0 && !daylight_saved)
+ daylight_saved = types[type_idxs[i]].isdst;
}
- __daylight = rule_stdoff != rule_dstoff;
+ __daylight = daylight_saved;
__timezone = -rule_stdoff;
done:
@@ -731,7 +734,7 @@ __tzfile_compute (__time64_t timer, int use_localtime,
}
struct ttinfo *info = &types[i];
- __daylight = rule_stdoff != rule_dstoff;
+ __daylight = daylight_saved;
__timezone = -rule_stdoff;
if (__tzname[0] == NULL)
diff --git a/timezone/Makefile b/timezone/Makefile
index a789c22d26..5002de39ad 100644
--- a/timezone/Makefile
+++ b/timezone/Makefile
@@ -23,7 +23,7 @@ subdir := timezone
include ../Makeconfig
others := zdump zic
-tests := test-tz tst-timezone tst-tzset tst-bz28707
+tests := test-tz tst-timezone tst-tzset tst-bz28707 tst-bz29951
generated-dirs += testdata
@@ -86,11 +86,13 @@ $(objpfx)tst-timezone.out: $(addprefix $(testdata)/, \
Europe/London)
$(objpfx)tst-tzset.out: $(addprefix $(testdata)/XT, 1 2 3 4)
$(objpfx)tst-bz28707.out: $(testdata)/XT5
+$(objpfx)tst-bz29951.out: $(testdata)/XT6
test-tz-ENV = TZDIR=$(testdata)
tst-timezone-ENV = TZDIR=$(testdata)
tst-tzset-ENV = TZDIR=$(testdata)
tst-bz28707-ENV = TZDIR=$(testdata)
+tst-bz29951-ENV = TZDIR=$(testdata)
# Note this must come second in the deps list for $(built-program-cmd) to work.
zic-deps = $(objpfx)zic $(leapseconds) yearistype
diff --git a/timezone/testdata/XT6 b/timezone/testdata/XT6
new file mode 100644
index 0000000000..07b393bb7d
Binary files /dev/null and b/timezone/testdata/XT6 differ
diff --git a/timezone/tst-bz29951.c b/timezone/tst-bz29951.c
new file mode 100644
index 0000000000..abd334683b
--- /dev/null
+++ b/timezone/tst-bz29951.c
@@ -0,0 +1,68 @@
+/* Check that daylight is set if the last DST transition did not change offset.
+ Copyright (C) 2023 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <support/check.h>
+#include <time.h>
+
+/* Set the specified time zone with error checking. */
+static void
+set_timezone (const char *name)
+{
+ TEST_VERIFY (setenv ("TZ", name, 1) == 0);
+ errno = 0;
+ tzset ();
+ TEST_COMPARE (errno, 0);
+}
+
+static int
+do_test (void)
+{
+ /* Test zone based on tz-2022g version of Africa/Tripoli. The last
+ DST transition coincided with a change in the standard time
+ offset, effectively making it a no-op.
+
+ Africa/Tripoli Thu Oct 24 23:59:59 2013 UT
+ = Fri Oct 25 01:59:59 2013 CEST isdst=1 gmtoff=7200
+ Africa/Tripoli Fri Oct 25 00:00:00 2013 UT
+ = Fri Oct 25 02:00:00 2013 EET isdst=0 gmtoff=7200
+ */
+ set_timezone ("XT6");
+ TEST_VERIFY (daylight != 0);
+ TEST_COMPARE (timezone, -7200);
+
+ /* Check that localtime re-initializes the two variables. */
+ daylight = timezone = 17;
+ time_t t = 844034401;
+ struct tm *tm = localtime (&t);
+ TEST_VERIFY (daylight != 0);
+ TEST_COMPARE (timezone, -7200);
+ TEST_COMPARE (tm->tm_year, 96);
+ TEST_COMPARE (tm->tm_mon, 8);
+ TEST_COMPARE (tm->tm_mday, 29);
+ TEST_COMPARE (tm->tm_hour, 23);
+ TEST_COMPARE (tm->tm_min, 0);
+ TEST_COMPARE (tm->tm_sec, 1);
+ TEST_COMPARE (tm->tm_gmtoff, 3600);
+ TEST_COMPARE (tm->tm_isdst, 0);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
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2023-01-10 16:03 [glibc/release/2.36/master] time: Set daylight to 1 for matching DST/offset change (bug 29951) Florian Weimer
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