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author | Joseph Myers <joseph@codesourcery.com> | 2018-05-18 11:57:15 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2018-05-18 11:57:15 +0000 |
commit | 78274dc8ceb21bb7efd8baef29e1f00031b9c1c6 (patch) | |
tree | 4312ee0c556f5057d52dad74b973a0fafa4098a8 | |
parent | 6f7fdeeb69776d0d2f67fb26f92ad2807445ca5e (diff) | |
download | glibc-78274dc8ceb21bb7efd8baef29e1f00031b9c1c6.tar.gz |
Fix year 2039 bug for localtime with 64-bit time_t (bug 22639).
Bug 22639 reports localtime failing to handle time offset transitions
correctly in 2039 and later on platforms with 64-bit time_t.
The problem is the use of SECSPERDAY (constant 86400) in calculations
such as
t = ((year - 1970) * 365
+ /* Compute the number of leapdays between 1970 and YEAR
(exclusive). There is a leapday every 4th year ... */
+ ((year - 1) / 4 - 1970 / 4)
/* ... except every 100th year ... */
- ((year - 1) / 100 - 1970 / 100)
/* ... but still every 400th year. */
+ ((year - 1) / 400 - 1970 / 400)) * SECSPERDAY;
where t is of type time_t and year is of type int. Before my commit
92bd70fb85bce57ac47ba5d8af008736832c955a (an update from tzcode,
included in 2.26 and later releases), SECSPERDAY was obtained from a
file imported from tzcode, where the value included a cast to
int_fast32_t. On 64-bit platforms, glibc defines int_fast32_t to be
long int, so 64-bit, but my patch resulted in it changing to int.
(The bug would probably have existed even before my patch for x32,
which has 64-bit time_t but 32-bit int_fast32_t, but I haven't
verified that.)
This patch fixes the problem by including a cast to time_t in the
definition of SECSPERDAY. (64-bit time support for 32-bit systems
should move such code that isn't a public interface to using the
internal 64-bit version of time_t throughout.)
Tested for x86_64 and x86.
[BZ #22639]
* time/tzset.c (SECSPERDAY): Cast to time_t.
* time/tst-y2039.c: New file.
* time/Makefile (tests): Add tst-y2039.
-rw-r--r-- | ChangeLog | 7 | ||||
-rw-r--r-- | time/Makefile | 2 | ||||
-rw-r--r-- | time/tst-y2039.c | 46 | ||||
-rw-r--r-- | time/tzset.c | 2 |
4 files changed, 55 insertions, 2 deletions
@@ -1,3 +1,10 @@ +2018-05-18 Joseph Myers <joseph@codesourcery.com> + + [BZ #22639] + * time/tzset.c (SECSPERDAY): Cast to time_t. + * time/tst-y2039.c: New file. + * time/Makefile (tests): Add tst-y2039. + 2018-05-17 Leonardo Sandoval <leonardo.sandoval.gonzalez@intel.com> * sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S diff --git a/time/Makefile b/time/Makefile index 0db1206820..ec3e39dcea 100644 --- a/time/Makefile +++ b/time/Makefile @@ -43,7 +43,7 @@ tests := test_time clocktest tst-posixtz tst-strptime tst_wcsftime \ tst-getdate tst-mktime tst-mktime2 tst-ftime_l tst-strftime \ tst-mktime3 tst-strptime2 bug-asctime bug-asctime_r bug-mktime1 \ tst-strptime3 bug-getdate1 tst-strptime-whitespace tst-ftime \ - tst-tzname + tst-tzname tst-y2039 include ../Rules diff --git a/time/tst-y2039.c b/time/tst-y2039.c new file mode 100644 index 0000000000..cdc6bca54b --- /dev/null +++ b/time/tst-y2039.c @@ -0,0 +1,46 @@ +/* Test for localtime bug in year 2039 (bug 22639). + Copyright (C) 2017-2018 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 + <http://www.gnu.org/licenses/>. */ + +#include <time.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <support/check.h> + +static int +do_test (void) +{ + TEST_VERIFY_EXIT (setenv ("TZ", "PST8PDT,M3.2.0,M11.1.0", 1) == 0); + tzset (); + if (sizeof (time_t) > 4) + { + time_t ouch = (time_t) 2187810000LL; + char buf[500]; + struct tm *tm = localtime (&ouch); + TEST_VERIFY_EXIT (tm != NULL); + TEST_VERIFY_EXIT (strftime (buf, sizeof buf, "%Y-%m-%d %H:%M:%S %Z", tm) + > 0); + puts (buf); + TEST_VERIFY (strcmp (buf, "2039-04-30 14:00:00 PDT") == 0); + } + else + FAIL_UNSUPPORTED ("32-bit time_t"); + return 0; +} + +#include <support/test-driver.c> diff --git a/time/tzset.c b/time/tzset.c index b51786704a..a828b9fb75 100644 --- a/time/tzset.c +++ b/time/tzset.c @@ -27,7 +27,7 @@ #include <timezone/tzfile.h> -#define SECSPERDAY 86400 +#define SECSPERDAY ((time_t) 86400) char *__tzname[2] = { (char *) "GMT", (char *) "GMT" }; int __daylight = 0; |