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Date:      Thu, 16 Dec 1999 21:16:20 +0100 (CET)
From:      Andre Albsmeier <andre.albsmeier@mchp.siemens.de>
To:        FreeBSD-gnats-submit@freebsd.org
Subject:   bin/15520: mktime() fails under certain conditions
Message-ID:  <199912162016.VAA97593@internal>

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>Number:         15520
>Category:       bin
>Synopsis:       mktime() fails under certain conditions
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Dec 16 12:20:01 PST 1999
>Closed-Date:
>Last-Modified:
>Originator:     Andre Albsmeier
>Release:        FreeBSD 3.4-RC i386
>Organization:
>Environment:

FreeBSD-3.4

>Description:

mktime() fails if it is called with a time that is exactly
the moment when daylight saving time is starting.

The configure program of certain gnu software tests mktime()
for the failure described above. This fails on FreeBSD and
so configure assumes there is no working mktime available.
This behaviour was observed when configure'ing gnu tar-1.1.3.


>How-To-Repeat:

The following program is the testing code of gnu's configure
plus three printf's to show the returned value and if the
problem exists. I have tried it also on HP-UX 10.20 and on
IRIX 5.3 where it works. In this cases the result returned
by mktime() is 891766800.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void main ()
{   
  time_t t;
  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;
  t=mktime(&tm);
  printf("%lu, ", t);
  if (t== (time_t)-1) {
    printf("Error\n");
    exit (1);
  }
  printf("OK\n");
}


For better understanding, here is the complete conftest.c that is used
by configure:

#line 4392 "configure"
#include "confdefs.h"
/* Test program from Paul Eggert (eggert@twinsun.com)
   and Tony Leneis (tony@plaza.ds.adp.com).  */
#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;
  now = mktime (&tm);
  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;

  /* This test makes some buggy mktime implementations loop.
     Give up after 60 seconds; a mktime slower than that
     isn't worth using anyway.  */
  alarm (60);

  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);
}

>Fix:
	
Unknown, unfortunatley...

>Release-Note:
>Audit-Trail:
>Unformatted:


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