glibc/sysdeps/unix/sysv/linux/x86/time.c

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/* time -- Get number of seconds since Epoch. Linux/x86 version.
Copyright (C) 2015-2021 Free Software Foundation, Inc.
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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
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<https://www.gnu.org/licenses/>. */
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y2038: linux: Provide __time64 implementation In the glibc the time function can use vDSO (on power and x86 the USE_IFUNC_TIME is defined), time syscall or 'default' time() from ./time/time.c (as a fallback). In this patch the last function (time) has been refactored and moved to ./sysdeps/unix/sysv/linux/time.c to be Linux specific. The new __time64 explicit 64 bit function for providing 64 bit value of seconds after epoch (by internally calling __clock_gettime64) has been introduced. Moreover, a 32 bit version - __time has been refactored to internally use __time64. The __time is now supposed to be used on systems still supporting 32 bit time (__TIMESIZE != 64) - hence the necessary check for time_t potential overflow. The iFUNC vDSO direct call optimization has been removed from both i686 and powerpc32 (USE_IFUNC_TIME is not defined for those architectures anymore). The Linux kernel does not provide a y2038 safe implementation of time neither it plans to provide it in the future, __clock_gettime64 should be used instead. Keeping support for this optimization would require to handle another build permutation (!__ASSUME_TIME64_SYSCALLS && USE_IFUNC_TIME which adds more complexity and has limited use (since the idea is to eventually have a y2038 safe glibc build). Build tests: ./src/scripts/build-many-glibcs.py glibcs Run-time tests: - Run specific tests on ARM/x86 32bit systems (qemu): https://github.com/lmajewski/meta-y2038 and run tests: https://github.com/lmajewski/y2038-tests/commits/master Above tests were performed with Y2038 redirection applied as well as without to test proper usage of both __time64 and __time. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
2020-10-14 11:45:43 +00:00
#ifdef __x86_64__
# define USE_IFUNC_TIME
#endif
#include <sysdeps/unix/sysv/linux/time.c>