mktime.m4

这是一个自动生成MAKEFILE的工具。相信大家都听说过。在LINUX工程项目里是很好的帮手。希望对大家有点帮助。

#serial 4

dnl From Jim Meyering.
dnl FIXME: this should migrate into libit.

AC_DEFUN([AM_FUNC_MKTIME],
[AC_REQUIRE([AC_HEADER_TIME])dnl
 AC_CHECK_HEADERS(sys/time.h unistd.h)
 AC_CHECK_FUNCS(alarm)
 AC_CACHE_CHECK([for working mktime], am_cv_func_working_mktime,
  [AC_TRY_RUN(
changequote(<<, >>)dnl
<</* Test program from Paul Eggert ([e-mail])
   and Tony Leneis ([e-mail]).  */
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif

#if HAVE_UNISTD_H
# include <unistd.h>
#endif

#if !HAVE_ALARM
# define alarm(X) /* empty */
#endif

/* Work around redefinition to rpl_putenv by other config tests.  */
#undef putenv

static time_t time_t_max;

/* Values we'll use to set the TZ environment variable.  */
static const char *const tz_strings[] = {
  (const char *) 0, "TZ=GMT0", "TZ=JST-9",
  "TZ=EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
};
#define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))

/* Fail if mktime fails to convert a date in the spring-forward gap.
   Based on a problem report from Andreas Jaeger.  */
static void
spring_forward_gap ()
{
  /* glibc (up to about 1998-10-07) failed this test) */
  struct tm tm;

  /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
     instead of "TZ=America/Vancouver" in order to detect the bug even
     on systems that don't support the Olson extension, or don't have the
     full zoneinfo tables installed.  */
  putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");

  tm.tm_year = 98;
  tm.tm_mon = 3;
  tm.tm_mday = 5;
  tm.tm_hour = 2;
  tm.tm_min = 0;
  tm.tm_sec = 0;
  tm.tm_isdst = -1;
  if (mktime (&tm) == (time_t)-1)
    exit (1);
}

static void
mktime_test (now)
     time_t now;
{
  struct tm *lt;
  if ((lt = localtime (&now)) && mktime (lt) != now)
    exit (1);
  now = time_t_max - now;
  if ((lt = localtime (&now)) && mktime (lt) != now)
    exit (1);
}

static void
irix_6_4_bug ()
{
  /* Based on code from Ariel Faigon.  */
  struct tm tm;
  tm.tm_year = 96;
  tm.tm_mon = 3;
  tm.tm_mday = 0;
  tm.tm_hour = 0;
  tm.tm_min = 0;
  tm.tm_sec = 0;
  tm.tm_isdst = -1;
  mktime (&tm);
  if (tm.tm_mon != 2 || tm.tm_mday != 31)
    exit (1);
}

static void
bigtime_test (j)
     int j;
{
  struct tm tm;
  time_t now;
  tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
  /* This test makes some buggy mktime implementations loop.
     Give up after 10 seconds.  */
  alarm (10);
  now = mktime (&tm);
  alarm (0);
  if (now != (time_t) -1)
    {
      struct tm *lt = localtime (&now);
      if (! (lt
	     && lt->tm_year == tm.tm_year
	     && lt->tm_mon == tm.tm_mon
	     && lt->tm_mday == tm.tm_mday
	     && lt->tm_hour == tm.tm_hour
	     && lt->tm_min == tm.tm_min
	     && lt->tm_sec == tm.tm_sec
	     && lt->tm_yday == tm.tm_yday
	     && lt->tm_wday == tm.tm_wday
	     && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
		  == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
	exit (1);
    }
}

int
main ()
{
  time_t t, delta;
  int i, j;

  for (time_t_max = 1; 0 < time_t_max; time_t_max *= 2)
    continue;
  time_t_max--;
  delta = time_t_max / 997; /* a suitable prime number */
  for (i = 0; i < N_STRINGS; i++)
    {
      if (tz_strings[i])
	putenv (tz_strings[i]);

      for (t = 0; t <= time_t_max - delta; t += delta)
	mktime_test (t);
      mktime_test ((time_t) 60 * 60);
      mktime_test ((time_t) 60 * 60 * 24);

      for (j = 1; 0 < j; j *= 2)
        bigtime_test (j);
      bigtime_test (j - 1);
    }
  irix_6_4_bug ();
  spring_forward_gap ();
  exit (0);
}
	      >>,
changequote([, ])dnl
	     am_cv_func_working_mktime=yes, am_cv_func_working_mktime=no,
	     dnl When crosscompiling, assume mktime is missing or broken.
	     am_cv_func_working_mktime=no)
  ])
  if test $am_cv_func_working_mktime = no; then
    LIBOBJS="$LIBOBJS mktime.o"
  fi
])