1/* Check if stat supports nanosecond resolution.
2 Copyright (C) 2021-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <fcntl.h>
21#include <support/check.h>
22#include <support/support.h>
23#include <support/timespec.h>
24#include <stdbool.h>
25#include <sys/stat.h>
26#include <sys/types.h>
27#include <unistd.h>
28
29bool
30support_stat_nanoseconds (const char *path)
31{
32 bool support = true;
33#ifdef __linux__
34 /* Obtain the original timestamp to restore at the end. */
35 struct stat ost;
36 TEST_VERIFY_EXIT (stat (path, &ost) == 0);
37
38 const struct timespec tsp[] = { { 0, TIMESPEC_HZ - 1 },
39 { 0, TIMESPEC_HZ / 2 } };
40 TEST_VERIFY_EXIT (utimensat (AT_FDCWD, path, tsp, 0) == 0);
41
42 struct stat st;
43 TEST_VERIFY_EXIT (stat (path, &st) == 0);
44
45 support = st.st_atim.tv_nsec == tsp[0].tv_nsec
46 && st.st_mtim.tv_nsec == tsp[1].tv_nsec;
47
48 /* Reset to original timestamps. */
49 const struct timespec otsp[] =
50 {
51 { ost.st_atim.tv_sec, ost.st_atim.tv_nsec },
52 { ost.st_mtim.tv_sec, ost.st_mtim.tv_nsec },
53 };
54 TEST_VERIFY_EXIT (utimensat (AT_FDCWD, path, otsp, 0) == 0);
55#endif
56 return support;
57}
58