Use clock_gettime to implement time.

Change the default implementation of time to call clock_gettime,
to align with new Linux ports that are expected to only implement
__NR_clock_gettime.  Arch-specific implementation that either call
the time vDSO or route to gettimeofday vDSO are not removed.

Also for Linux, CLOCK_REALTIME_COARSE is used instead of generic
CLOCK_REALTIME clockid.  This takes less CPU time and its behavior
better matches what the current glibc does.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
powerpc64-linux-gnu, powerpc-linux-gnu, and aarch64-linux-gnu.

Co-authored-by: Zack Weinberg <zackw@panix.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>

1 files changed, 6 insertions, 7 deletions

diff --git a/time/time.c b/time/time.c
index b53a06e29c..e6e5eeff7e 100644
--- a/time/time.c
+++ b/time/time.c
@@ -15,19 +15,18 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <errno.h>
 #include <time.h>
+#include <time-clockid.h>
 
 /* Return the time now, and store it in *TIMER if not NULL.  */
 time_t
 time (time_t *timer)
 {
-  __set_errno (ENOSYS);
+  struct timespec ts;
+  __clock_gettime (TIME_CLOCK_GETTIME_CLOCKID, &ts);
 
-  if (timer != NULL)
-    *timer = (time_t) -1;
-  return (time_t) -1;
+  if (timer)
+    *timer = ts.tv_sec;
+  return ts.tv_sec;
 }
 libc_hidden_def (time)
-
-stub_warning (time)