Ticket #19047: foo.c

#include <stdio.h>
#include <string.h>
#include <time.h>
#include <assert.h>

int
main ()
{
  time_t t = 1509000003; /* 2017-10-26 06:40:03 */
  struct tm tm;
  struct tm *result = gmtime_r (&t, &tm);
  assert (result == &tm);
  assert (result->tm_sec == 3);
  assert (result->tm_min == 40);
  assert (result->tm_hour == 6);
  assert (result->tm_mday == 26);
  assert (result->tm_mon == 10 - 1);
  assert (result->tm_year == 2017 - 1900);
  assert (result->tm_wday == 4);
  assert (result->tm_yday == 298);
  assert (result->tm_isdst == 0);

  assert (result->tm_gmtoff == 0);

  printf ("tm_zone = %s\n", result->tm_zone == NULL ? "(null)" : result->tm_zone);
  assert (strcmp (result->tm_zone, "GMT") == 0 /* glibc, NetBSD, OpenBSD, Minix, Cygwin, Android */
          || strcmp (result->tm_zone, "UTC") == 0 /* musl, macOS, FreeBSD */);

  printf ("OK\n");
}