[v4] tst: Provide test for difftime

This change adds new test to assess difftime's functionality by
adding some arbitrary offsets to current time_t value (read via
time).

If 64 bit time_t is supported, the same procedure is applied around
the threshold of Y2038 time overflow.

---
Changes for v2:
- Remove FAIL_UNSUPPORTED() when sizeof (time_t) <= 4

Changes for v3:
- Simplify the signature of test_difftime_helper (remove the start
  argument)
- Use just some reproductible value of starting time_t instead of
  calling time (NULL)

Changes for v4:
- Use __builtin_add_overflow instead of sizeof (time_t) > 4 to check
  if time_t has overflowed.
---
 time/Makefile       |  2 +-
 time/tst-difftime.c | 56 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 time/tst-difftime.c

Dear Community,

> This change adds new test to assess difftime's functionality by
> adding some arbitrary offsets to current time_t value (read via
> time).
> 
> If 64 bit time_t is supported, the same procedure is applied around
> the threshold of Y2038 time overflow.
> 
> ---
> Changes for v2:
> - Remove FAIL_UNSUPPORTED() when sizeof (time_t) <= 4
> 
> Changes for v3:
> - Simplify the signature of test_difftime_helper (remove the start
>   argument)
> - Use just some reproductible value of starting time_t instead of
>   calling time (NULL)
> 
> Changes for v4:
> - Use __builtin_add_overflow instead of sizeof (time_t) > 4 to check
>   if time_t has overflowed.

Are there any more comments regarding this test? Is it eligible for
pulling?

> ---
>  time/Makefile       |  2 +-
>  time/tst-difftime.c | 56
> +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 57
> insertions(+), 1 deletion(-) create mode 100644 time/tst-difftime.c
> 
> diff --git a/time/Makefile b/time/Makefile
> index 486fb02ecb..7de2ce0196 100644
> --- a/time/Makefile
> +++ b/time/Makefile
> @@ -51,7 +51,7 @@ tests	:= test_time clocktest tst-posixtz
> tst-strptime tst_wcsftime \ tst-clock tst-clock2 tst-clock_nanosleep
> tst-cpuclock1 \ tst-adjtime tst-clock-y2038 tst-clock2-y2038 \
>  	   tst-cpuclock1-y2038 tst-clock_nanosleep-y2038
> tst-clock_settime \
> -	   tst-clock_adjtime tst-ctime
> +	   tst-clock_adjtime tst-ctime tst-difftime
>  
>  include ../Rules
>  
> diff --git a/time/tst-difftime.c b/time/tst-difftime.c
> new file mode 100644
> index 0000000000..262f3d1db7
> --- /dev/null
> +++ b/time/tst-difftime.c
> @@ -0,0 +1,56 @@
> +/* Test for difftime
> +   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>
> +
> +static void
> +test_difftime_helper (time_t t1, time_t t0, double exp_val)
> +{
> +  double sub = difftime (t1, t0);
> +  if (sub != exp_val)
> +    FAIL_EXIT1 ("*** Difftime returned %f (expected %f)\n", sub,
> exp_val); +}
> +
> +static int
> +do_test (void)
> +{
> +  time_t t = 1383791700; /* Provide reproductible start value.  */
> +
> +  /* Check if difftime works with current time.  */
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  t = 0x7FFFFFFF;
> +  /* Check if we run on port with 32 bit time_t size */
> +  time_t tov;
> +  if (__builtin_add_overflow (t, 1, &tov))
> +    return 0;
> +
> +  /* Check if the time is converted after 32 bit time_t overflow.  */
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  t = tov;
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  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

On 05/02/2021 08:52, Lukasz Majewski wrote:
> This change adds new test to assess difftime's functionality by
> adding some arbitrary offsets to current time_t value (read via
> time).
> 
> If 64 bit time_t is supported, the same procedure is applied around
> the threshold of Y2038 time overflow.
> 
> ---
> Changes for v2:
> - Remove FAIL_UNSUPPORTED() when sizeof (time_t) <= 4
> 
> Changes for v3:
> - Simplify the signature of test_difftime_helper (remove the start
>   argument)
> - Use just some reproductible value of starting time_t instead of
>   calling time (NULL)
> 
> Changes for v4:
> - Use __builtin_add_overflow instead of sizeof (time_t) > 4 to check
>   if time_t has overflowed.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  time/Makefile       |  2 +-
>  time/tst-difftime.c | 56 +++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 57 insertions(+), 1 deletion(-)
>  create mode 100644 time/tst-difftime.c
> 
> diff --git a/time/Makefile b/time/Makefile
> index 486fb02ecb..7de2ce0196 100644
> --- a/time/Makefile
> +++ b/time/Makefile
> @@ -51,7 +51,7 @@ tests	:= test_time clocktest tst-posixtz tst-strptime tst_wcsftime \
>  	   tst-clock tst-clock2 tst-clock_nanosleep tst-cpuclock1 \
>  	   tst-adjtime tst-clock-y2038 tst-clock2-y2038 \
>  	   tst-cpuclock1-y2038 tst-clock_nanosleep-y2038 tst-clock_settime \
> -	   tst-clock_adjtime tst-ctime
> +	   tst-clock_adjtime tst-ctime tst-difftime
>  
>  include ../Rules
>  

Ok.

> diff --git a/time/tst-difftime.c b/time/tst-difftime.c
> new file mode 100644
> index 0000000000..262f3d1db7
> --- /dev/null
> +++ b/time/tst-difftime.c
> @@ -0,0 +1,56 @@
> +/* Test for difftime
> +   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>
> +
> +static void
> +test_difftime_helper (time_t t1, time_t t0, double exp_val)
> +{
> +  double sub = difftime (t1, t0);
> +  if (sub != exp_val)
> +    FAIL_EXIT1 ("*** Difftime returned %f (expected %f)\n", sub, exp_val);
> +}
> +
> +static int
> +do_test (void)
> +{
> +  time_t t = 1383791700; /* Provide reproductible start value.  */
> +
> +  /* Check if difftime works with current time.  */
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  t = 0x7FFFFFFF;
> +  /* Check if we run on port with 32 bit time_t size */
> +  time_t tov;
> +  if (__builtin_add_overflow (t, 1, &tov))
> +    return 0;
> +
> +  /* Check if the time is converted after 32 bit time_t overflow.  */
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  t = tov;
> +  test_difftime_helper (t + 1800, t - 1800, 3600.0);
> +  test_difftime_helper (t - 1800, t + 1800, -3600.0);
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
> 

Ok.