tst: Add test for clock_settime

This code brings test to check if time on target machine is properly set.
To avoid any issues with altering the time:

- The time, which was set before the test was executed is restored.

- The time is altered only when cross-test-ssh.sh is executed with
  --allow-time-setting flag

Reviewed-by: DJ Delorie <dj@redhat.com>

2 files changed, 46 insertions, 1 deletions

diff --git a/time/Makefile b/time/Makefile
index a52b6b9..b3c5368 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -48,7 +48,7 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
 	   tst-strptime3 bug-getdate1 tst-strptime-whitespace tst-ftime \
 	   tst-tzname tst-y2039 bug-mktime4 tst-strftime2 tst-strftime3 \
 	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1 \
-	   tst-adjtime tst-ctime tst-difftime tst-mktime4
+	   tst-adjtime tst-ctime tst-difftime tst-mktime4 tst-clock_settime
 
 include ../Rules
 
diff --git a/time/tst-clock_settime.c b/time/tst-clock_settime.c
new file mode 100644
index 0000000..90a1656
--- /dev/null
+++ b/time/tst-clock_settime.c
@@ -0,0 +1,45 @@
+/* Test for clock_settime
+   Copyright (C) 2021 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 <time.h>
+#include <support/check.h>
+#include <support/xtime.h>
+
+#define TIMESPEC_SEC_Y2038_OV 0x7FFFFFFF
+#define FUTURE_TIME (TIMESPEC_SEC_Y2038_OV - 10)
+
+static int
+do_test (void)
+{
+  const struct timespec tv = { FUTURE_TIME, 0};
+  struct timespec tv_future, tv_now;
+
+  tv_now = xclock_now(CLOCK_REALTIME);
+  xclock_settime(CLOCK_REALTIME, &tv);
+  tv_future = xclock_now(CLOCK_REALTIME);
+
+  /* Restore old time value on target machine.  */
+  xclock_settime(CLOCK_REALTIME, (const struct timespec*) &tv_now);
+
+  if (tv_future.tv_sec < tv.tv_sec)
+    FAIL_EXIT1 ("clock_settime set wrong time!\n");
+
+  return 0;
+}
+
+#include <support/test-driver.c>