[glibc/azanella/y2038] tst: Add test for clock_adjtime

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=91b32cbf0591d63acb3967026456222069c0edc0

commit 91b32cbf0591d63acb3967026456222069c0edc0
Author: Lukasz Majewski <lukma@denx.de>
Date:   Wed Jan 20 12:10:42 2021 +0100

    tst: Add test for clock_adjtime
    
    This code brings test to check if time on target machine is properly
    adjusted.
    The time is altered only when cross-test-ssh.sh is executed with
    --allow-time-setting flag
    As the delta added to CLOCK_REALTIME is only 1ms the original time is
    not restored and further tests are executed with this bias.

Diff:
---
 time/Makefile            |  3 ++-
 time/tst-clock_adjtime.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/time/Makefile b/time/Makefile
index b3c5368c3b..0d571fb777 100644
--- a/time/Makefile
+++ b/time/Makefile
@@ -48,7 +48,8 @@ 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-clock_settime
+	   tst-adjtime tst-ctime tst-difftime tst-mktime4 tst-clock_settime \
+	   tst-clock_adjtime
 
 include ../Rules
 
diff --git a/time/tst-clock_adjtime.c b/time/tst-clock_adjtime.c
new file mode 100644
index 0000000000..ece68acc5f
--- /dev/null
+++ b/time/tst-clock_adjtime.c
@@ -0,0 +1,61 @@
+/* Test for clock_adjtime
+   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 <stdlib.h>
+#include <sys/time.h>
+#include <sys/timex.h>
+#include <support/check.h>
+#include <support/xtime.h>
+
+static int
+do_test (void)
+{
+  struct timespec tv_then, tv_now;
+  struct timex delta;
+
+  /* Check if altering target time is allowed.  */
+  if (getenv (SETTIME_ENV_NAME) == NULL)
+    FAIL_UNSUPPORTED ("clock_adjtime is executed only when "\
+                      SETTIME_ENV_NAME" is set\n");
+
+  tv_then = xclock_now (CLOCK_REALTIME);
+
+  /* Setup time value to adjust - 1 ms. */
+  delta.time.tv_sec = 0;
+  delta.time.tv_usec = 1000;
+  delta.modes = ADJ_SETOFFSET;
+
+  int ret = clock_adjtime (CLOCK_REALTIME, &delta);
+  if (ret == -1)
+    FAIL_EXIT1 ("*** clock_adjtime failed: %m\n");
+
+  tv_now = xclock_now (CLOCK_REALTIME);
+
+  /* Check difference between timerfd_gettime calls.  */
+  long long int diff = tv_now.tv_sec - tv_then.tv_sec;
+  diff *= 1000000000;
+  diff += tv_now.tv_nsec - tv_then.tv_nsec;
+  /* The adjustment cannot be large than 10 ms.  */
+  if (diff > 10000000)
+    FAIL_EXIT1 ("clock_adjtime set wrong time!\n");
+
+  return 0;
+}
+
+#include <support/test-driver.c>