glibc/time/tst-difftime.c

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/* 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>