glibc/support/support_stat_nanoseconds.c

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/* Check if stat supports nanosecond resolution.
Copyright (C) 2021-2022 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 <fcntl.h>
#include <support/check.h>
#include <support/support.h>
#include <support/timespec.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
bool
support_stat_nanoseconds (const char *path)
{
bool support = true;
#ifdef __linux__
/* Obtain the original timestamp to restore at the end. */
struct stat ost;
TEST_VERIFY_EXIT (stat (path, &ost) == 0);
const struct timespec tsp[] = { { 0, TIMESPEC_HZ - 1 },
{ 0, TIMESPEC_HZ / 2 } };
TEST_VERIFY_EXIT (utimensat (AT_FDCWD, path, tsp, 0) == 0);
struct stat st;
TEST_VERIFY_EXIT (stat (path, &st) == 0);
support = st.st_atim.tv_nsec == tsp[0].tv_nsec
&& st.st_mtim.tv_nsec == tsp[1].tv_nsec;
/* Reset to original timestamps. */
const struct timespec otsp[] =
{
{ ost.st_atim.tv_sec, ost.st_atim.tv_nsec },
{ ost.st_mtim.tv_sec, ost.st_mtim.tv_nsec },
};
TEST_VERIFY_EXIT (utimensat (AT_FDCWD, path, otsp, 0) == 0);
#endif
return support;
}