[PATCH] tst: Add test for adjtime

[Lukasz Majewski]

Dear Community,

> This code provides 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 is only 1 sec the original time is not
> restored and further tests are executed with this bias.
> 
> It is important to note that adjtime() adjusts the system time with
> small ammounts in each second (it is in fact a wrapper on
> clock_adjtime with modes = ADJ_OFFSET_SINGLESHOT. In other words some
> seconds (may be a random value) needs to elapse until the required
> time offset is added to the clock. It may take considerable time (in
> minutes) to adjust clock by e.g. 1 second.
> 
> To handle that the struct timeval odelta is passed to adjtime (NULL,
> &odelta) to get information of the still required delta to be added
> to clock. This is done in loop until its members are equal to 0.
> 
> As a reference - CLOCK_MONOTONIC is used to check if CLOCK_REALTIME
> has been adjusted. The difference between them is measured.

Feedback more than welcome. Are there any comments regarding this patch?

> ---
>  sysdeps/unix/sysv/linux/Makefile      |  2 +-
>  sysdeps/unix/sysv/linux/tst-adjtime.c | 82
> +++++++++++++++++++++++++++ 2 files changed, 83 insertions(+), 1
> deletion(-) create mode 100644 sysdeps/unix/sysv/linux/tst-adjtime.c
> 
> diff --git a/sysdeps/unix/sysv/linux/Makefile
> b/sysdeps/unix/sysv/linux/Makefile index 6a45ac820a..25d2f05183 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -113,7 +113,7 @@ tests += tst-clone tst-clone2 tst-clone3
> tst-fanotify tst-personality \ tst-tgkill tst-sysvsem-linux
> tst-sysvmsg-linux tst-sysvshm-linux \ tst-timerfd tst-ppoll
> tst-futimens tst-utime tst-utimes \ tst-clock_adjtime tst-adjtimex
> tst-ntp_adjtime tst-futimes \
> -	 tst-lutimes tst-ntp_gettime tst-ntp_gettimex
> +	 tst-lutimes tst-ntp_gettime tst-ntp_gettimex tst-adjtime
>  tests-internal += tst-ofdlocks-compat tst-sigcontext-get_pc
>  tests-time64 += \
>    tst-futimes-time64\
> diff --git a/sysdeps/unix/sysv/linux/tst-adjtime.c
> b/sysdeps/unix/sysv/linux/tst-adjtime.c new file mode 100644
> index 0000000000..b381963be8
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-adjtime.c
> @@ -0,0 +1,82 @@
> +/* Test for 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/timerfd.h>
> +#include <support/check.h>
> +#include <support/xunistd.h>
> +#include <support/timespec.h>
> +
> +#define TIMEOUT (60*10)
> +#define ADJTIME_LOOP_SLEEP 10000
> +
> +static int
> +do_test (void)
> +{
> +  struct timespec tv_then, tv_now, tv_then_m, tv_now_m;
> +  struct timeval delta, odelta;
> +  int ret;
> +
> +  /* Check if altering target time is allowed.  */
> +  if (getenv (SETTIME_ENV_NAME) == NULL)
> +    FAIL_UNSUPPORTED ("adjtime is executed only when "\
> +                      SETTIME_ENV_NAME" is set\n");
> +
> +  tv_then = xclock_now (CLOCK_REALTIME);
> +  tv_then_m = xclock_now (CLOCK_MONOTONIC);
> +
> +  /* Setup time value to adjust - 1 sec. */
> +  delta.tv_sec = 1;
> +  delta.tv_usec = 0;
> +
> +  ret = adjtime (&delta, NULL);
> +  if (ret == -1)
> +    FAIL_EXIT1 ("adjtime failed: %m\n");
> +
> +  /* As adjtime adjust clock time gradually by some small percentage
> +     of delta in each second one needs to check if this process has
> +     been finished.  */
> +  do {
> +    ret = adjtime (NULL, &odelta);
> +    if (ret == -1)
> +      FAIL_EXIT1 ("adjtime failed: %m\n");
> +
> +    ret = usleep (ADJTIME_LOOP_SLEEP);
> +    if (ret != 0)
> +      FAIL_EXIT1 ("usleep failed: %m\n");
> +
> +  } while ( ! (odelta.tv_sec == 0 && odelta.tv_usec == 0));
> +
> +  tv_now = xclock_now (CLOCK_REALTIME);
> +  tv_now_m = xclock_now (CLOCK_MONOTONIC);
> +
> +  /* Check if adjtime adjusted the system time.  */
> +  struct timespec r = timespec_sub (tv_now, tv_then);
> +  struct timespec r_m = timespec_sub (tv_now_m, tv_then_m);
> +
> +  struct timespec r_adjtime = timespec_sub (r, r_m);
> +
> +  TEST_COMPARE (support_timespec_check_in_range
> +                ((struct timespec) { 1, 0 }, r_adjtime, 0.9, 1.1),
> 1); +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>




Best regards,

Lukasz Majewski

--

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