glibc/time/tst-y2039.c

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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.
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/* Test for localtime bug in year 2039 (bug 22639).
Copyright (C) 2017-2020 Free Software Foundation, Inc.
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.
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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
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
2019-09-07 05:40:42 +00:00
<https://www.gnu.org/licenses/>. */
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.
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#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>