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io: Check at runtime if timestamp supports nanoseconds

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Now that non-LFS stat function is implemented on to on LFS, it will
use statx when available.  It allows to check for nanosecond timestamp
if the kernel supports __NR_statx.

Checked on s390-linux-gnu with 4.12.14 kernel.
This commit is contained in:
Adhemerval Zanella
2021-03-29 14:40:30 -03:00
parent 18f0afa848
commit bfddda2570
3 changed files with 40 additions and 9 deletions
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7
io/tst-stat.c
View File

@ -25,6 +25,7 @@
#include <support/xunistd.h> #include <support/xunistd.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/sysmacros.h> #include <sys/sysmacros.h>
#include <stdio.h>
#include <unistd.h> #include <unistd.h>
static void static void
@ -73,6 +74,10 @@ do_test (void)
test_t tests[] = { stat_check, lstat_check, fstat_check, fstatat_check }; test_t tests[] = { stat_check, lstat_check, fstat_check, fstatat_check };
bool check_ns = support_stat_nanoseconds (path);
if (!check_ns)
printf ("warning: timestamp with nanoseconds not supportted\n");
for (int i = 0; i < array_length (tests); i++) for (int i = 0; i < array_length (tests); i++)
{ {
struct stat st; struct stat st;
@ -92,7 +97,7 @@ do_test (void)
TEST_COMPARE (stx.stx_ctime.tv_sec, st.st_ctim.tv_sec); TEST_COMPARE (stx.stx_ctime.tv_sec, st.st_ctim.tv_sec);
TEST_COMPARE (stx.stx_mtime.tv_sec, st.st_mtim.tv_sec); TEST_COMPARE (stx.stx_mtime.tv_sec, st.st_mtim.tv_sec);
if (support_stat_nanoseconds ()) if (check_ns)
{ {
TEST_COMPARE (stx.stx_ctime.tv_nsec, st.st_ctim.tv_nsec); TEST_COMPARE (stx.stx_ctime.tv_nsec, st.st_ctim.tv_nsec);
TEST_COMPARE (stx.stx_mtime.tv_nsec, st.st_mtim.tv_nsec); TEST_COMPARE (stx.stx_mtime.tv_nsec, st.st_mtim.tv_nsec);

2
support/support.h
View File

@ -142,7 +142,7 @@ static __inline bool support_path_support_time64 (const char *path)
} }
/* Return true if stat supports nanoseconds resolution. */ /* Return true if stat supports nanoseconds resolution. */
extern bool support_stat_nanoseconds (void); extern bool support_stat_nanoseconds (const char *path);
__END_DECLS __END_DECLS

40
support/support_stat_nanoseconds.c
View File

@ -16,16 +16,42 @@
License along with the GNU C Library; if not, see License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */ <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 <stdbool.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
bool bool
support_stat_nanoseconds (void) support_stat_nanoseconds (const char *path)
{ {
/* s390 stat64 compat symbol does not support nanoseconds resolution bool support;
and it used on non-LFS [f,l]stat[at] implementations. */ #ifdef __linux__
#if defined __linux__ && !defined __s390x__ && defined __s390__ /* Obtain the original timestamp to restore at the end. */
return false; struct stat ost;
#else TEST_VERIFY_EXIT (stat (path, &ost) == 0);
return true;
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 #endif
return support;
} }