From 78274dc8ceb21bb7efd8baef29e1f00031b9c1c6 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 18 May 2018 11:57:15 +0000 Subject: 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. --- ChangeLog | 7 +++++++ time/Makefile | 2 +- time/tst-y2039.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ time/tzset.c | 2 +- 4 files changed, 55 insertions(+), 2 deletions(-) create mode 100644 time/tst-y2039.c diff --git a/ChangeLog b/ChangeLog index 3b25fc9..4a2d978 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2018-05-18 Joseph Myers + + [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 * sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S diff --git a/time/Makefile b/time/Makefile index 0db1206..ec3e39d 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 0000000..cdc6bca --- /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 + . */ + +#include +#include +#include +#include +#include + +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 diff --git a/time/tzset.c b/time/tzset.c index b517867..a828b9f 100644 --- a/time/tzset.c +++ b/time/tzset.c @@ -27,7 +27,7 @@ #include -#define SECSPERDAY 86400 +#define SECSPERDAY ((time_t) 86400) char *__tzname[2] = { (char *) "GMT", (char *) "GMT" }; int __daylight = 0; -- cgit v1.1