[PATCH v2] 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 amounts 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.
> 
> ---
> Changes for v2:
> - Correct code indentation
> ---

Gentle ping on this patch. Is this approach acceptable for testing
adjtime? 

>  sysdeps/unix/sysv/linux/Makefile      |  3 +-
>  sysdeps/unix/sysv/linux/tst-adjtime.c | 83
> +++++++++++++++++++++++++++ 2 files changed, 85 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 ddc1e748e6..30c8629386 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -113,7 +113,8 @@ 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-ntp_gettime \
> -	 tst-ntp_gettimex tst-sigtimedwait tst-futimes tst-lutimes
> +	 tst-ntp_gettimex tst-sigtimedwait tst-futimes tst-lutimes \
> +	 tst-adjtime
>  
>  # Test for the symbol version of fcntl that was replaced in glibc
> 2.28. ifeq ($(have-GLIBC_2.27)$(build-shared),yesyes)
> diff --git a/sysdeps/unix/sysv/linux/tst-adjtime.c
> b/sysdeps/unix/sysv/linux/tst-adjtime.c new file mode 100644
> index 0000000000..4b24fcb890
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/tst-adjtime.c
> @@ -0,0 +1,83 @@
> +/* 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

--

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 488 bytes
Desc: OpenPGP digital signature
URL: <https://sourceware.org/pipermail/libc-alpha/attachments/20210331/7ae2b432/attachment.sig>