* [PATCH] time: Set daylight to 1 for matching DST/offset change (bug 29951)
@ 2023-01-02 11:18 Florian Weimer
2023-01-02 11:44 ` Andreas Schwab
0 siblings, 1 reply; 3+ messages in thread
From: Florian Weimer @ 2023-01-02 11:18 UTC (permalink / raw)
To: libc-alpha
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.
Tested on i686-linux-gnu and x86_64-linux-gnu.
---
time/tzfile.c | 46 ++++++++++++++++++--------------
timezone/Makefile | 4 ++-
timezone/testdata/XT6 | Bin 0 -> 625 bytes
timezone/tst-bz29951.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 99 insertions(+), 21 deletions(-)
diff --git a/time/tzfile.c b/time/tzfile.c
index 394b098856..443e40419f 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>
@@ -440,34 +444,36 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
if (num_transitions == 0)
/* Use the first rule (which should also be the only one). */
- rule_stdoff = rule_dstoff = types[0].offset;
+ {
+ rule_stdoff = rule_dstoff = types[0].offset;
+ daylight_saved = 0;
+ }
else
{
- int stdoff_set = 0, dstoff_set = 0;
- rule_stdoff = rule_dstoff = 0;
+ daylight_saved = 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 seet 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 +737,7 @@ __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 $(leapseconds) yearistype
diff --git a/timezone/testdata/XT6 b/timezone/testdata/XT6
new file mode 100644
index 0000000000000000000000000000000000000000..07b393bb7db14cef1e906ebe63cfbbe8cddc79d5
GIT binary patch
literal 625
zcmb`@&nrYh0KoCtT?f{Wo{Q(l;<399B=szg#O_6Gtap+!4%F^xj&jiEPvGPrIXXyc
z%Rvq<PFu=NqS>-3N{@?jVZM*EQs%vx@B49?`FM-@HCOyP9P_uv%;tl)i^Sd8iFF@8
zl9lyqtMa(2t3%_edRW%a*-O7=ds5o9@5=rd(5+AXe%tM`Y%d@C9p?`+R@(48_if#^
zQ?I(WUZkU@RnN+%?#*4PcsimJsj#0+j>*1>Q{T<L%Hi~=N{tls+}^I3_il>0e5n`?
z1y|&!-*2qu3%3vrOPnO;gv@@MEK$d^Xq=h##8hU1#S<Aby+0iK(+mzyIXne`f)La|
zP%wfT5DE$#0)~PU)BsVCC{PqE3K#{A0!P8408$VskQ7V`C<T=QOTnc8Q;;dp6l@0I
N^k31VMt;zZegQ-UsTu$P
literal 0
HcmV?d00001
diff --git a/timezone/tst-bz29951.c b/timezone/tst-bz29951.c
new file mode 100644
index 0000000000..357ebf3da7
--- /dev/null
+++ b/timezone/tst-bz29951.c
@@ -0,0 +1,70 @@
+/* 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_COMPARE (daylight, 1);
+ 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_COMPARE (daylight, 1);
+ 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);
+ TEST_COMPARE (daylight, 1);
+ TEST_COMPARE (timezone, -7200);
+
+ return 0;
+}
+
+#include <support/test-driver.c>
base-commit: a09183aed7bb8ace211e042b2e6e982bcc004957
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] time: Set daylight to 1 for matching DST/offset change (bug 29951)
2023-01-02 11:18 [PATCH] time: Set daylight to 1 for matching DST/offset change (bug 29951) Florian Weimer
@ 2023-01-02 11:44 ` Andreas Schwab
2023-01-02 11:56 ` Florian Weimer
0 siblings, 1 reply; 3+ messages in thread
From: Andreas Schwab @ 2023-01-02 11:44 UTC (permalink / raw)
To: Florian Weimer via Libc-alpha; +Cc: Florian Weimer
On Jan 02 2023, Florian Weimer via Libc-alpha wrote:
> + /* Keep searching to seet if there is a DST rule. This
s/seet/see/
> + /* Check that localtime re-initializes the two variables. */
> + daylight = timezone = 17;
> + time_t t = 844034401;
> + struct tm *tm = localtime (&t);
> + TEST_COMPARE (daylight, 1);
The manual documents only a non-zero value.
> + TEST_COMPARE (daylight, 1);
> + TEST_COMPARE (timezone, -7200);
Duplicate tests.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] time: Set daylight to 1 for matching DST/offset change (bug 29951)
2023-01-02 11:44 ` Andreas Schwab
@ 2023-01-02 11:56 ` Florian Weimer
0 siblings, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2023-01-02 11:56 UTC (permalink / raw)
To: Andreas Schwab; +Cc: Florian Weimer via Libc-alpha
* Andreas Schwab:
> On Jan 02 2023, Florian Weimer via Libc-alpha wrote:
>
>> + /* Keep searching to seet if there is a DST rule. This
>
> s/seet/see/
>
>> + /* Check that localtime re-initializes the two variables. */
>> + daylight = timezone = 17;
>> + time_t t = 844034401;
>> + struct tm *tm = localtime (&t);
>> + TEST_COMPARE (daylight, 1);
>
> The manual documents only a non-zero value.
>
>> + TEST_COMPARE (daylight, 1);
>> + TEST_COMPARE (timezone, -7200);
>
> Duplicate tests.
Thanks, I'm going to send a fixed version.
Florian
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-01-02 11:18 [PATCH] time: Set daylight to 1 for matching DST/offset change (bug 29951) Florian Weimer
2023-01-02 11:44 ` Andreas Schwab
2023-01-02 11:56 ` Florian Weimer
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