1 files changed, 665 insertions, 0 deletions

diff --git a/gl/mktime.c b/gl/mktime.c
new file mode 100644
index 00000000..0f30d43f
--- /dev/null
+++ b/gl/mktime.c
@@ -0,0 +1,665 @@
+/* Convert a `struct tm' to a time_t value.
+   Copyright (C) 1993-1999, 2002-2005, 2006, 2007 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Paul Eggert <eggert@twinsun.com>.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* Define this to have a standalone program to test this implementation of
+   mktime.  */
+/* #define DEBUG 1 */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+/* Assume that leap seconds are possible, unless told otherwise.
+   If the host has a `zic' command with a `-L leapsecondfilename' option,
+   then it supports leap seconds; otherwise it probably doesn't.  */
+#ifndef LEAP_SECONDS_POSSIBLE
+# define LEAP_SECONDS_POSSIBLE 1
+#endif
+
+#include <time.h>
+
+#include <limits.h>
+
+#include <string.h>             /* For the real memcpy prototype.  */
+
+#if DEBUG
+# include <stdio.h>
+# include <stdlib.h>
+/* Make it work even if the system's libc has its own mktime routine.  */
+# define mktime my_mktime
+#endif /* DEBUG */
+
+/* Shift A right by B bits portably, by dividing A by 2**B and
+   truncating towards minus infinity.  A and B should be free of side
+   effects, and B should be in the range 0 <= B <= INT_BITS - 2, where
+   INT_BITS is the number of useful bits in an int.  GNU code can
+   assume that INT_BITS is at least 32.
+
+   ISO C99 says that A >> B is implementation-defined if A < 0.  Some
+   implementations (e.g., UNICOS 9.0 on a Cray Y-MP EL) don't shift
+   right in the usual way when A < 0, so SHR falls back on division if
+   ordinary A >> B doesn't seem to be the usual signed shift.  */
+#define SHR(a, b)       \
+  (-1 >> 1 == -1        \
+   ? (a) >> (b)         \
+   : (a) / (1 << (b)) - ((a) % (1 << (b)) < 0))
+
+/* The extra casts in the following macros work around compiler bugs,
+   e.g., in Cray C 5.0.3.0.  */
+
+/* True if the arithmetic type T is an integer type.  bool counts as
+   an integer.  */
+#define TYPE_IS_INTEGER(t) ((t) 1.5 == 1)
+
+/* True if negative values of the signed integer type T use two's
+   complement, ones' complement, or signed magnitude representation,
+   respectively.  Much GNU code assumes two's complement, but some
+   people like to be portable to all possible C hosts.  */
+#define TYPE_TWOS_COMPLEMENT(t) ((t) ~ (t) 0 == (t) -1)
+#define TYPE_ONES_COMPLEMENT(t) ((t) ~ (t) 0 == 0)
+#define TYPE_SIGNED_MAGNITUDE(t) ((t) ~ (t) 0 < (t) -1)
+
+/* True if the arithmetic type T is signed.  */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+
+/* The maximum and minimum values for the integer type T.  These
+   macros have undefined behavior if T is signed and has padding bits.
+   If this is a problem for you, please let us know how to fix it for
+   your host.  */
+#define TYPE_MINIMUM(t) \
+  ((t) (! TYPE_SIGNED (t) \
+        ? (t) 0 \
+        : TYPE_SIGNED_MAGNITUDE (t) \
+        ? ~ (t) 0 \
+        : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1)))
+#define TYPE_MAXIMUM(t) \
+  ((t) (! TYPE_SIGNED (t) \
+        ? (t) -1 \
+        : ~ (~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))))
+
+#ifndef TIME_T_MIN
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
+#endif
+#ifndef TIME_T_MAX
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
+#endif
+#define TIME_T_MIDPOINT (SHR (TIME_T_MIN + TIME_T_MAX, 1) + 1)
+
+/* Verify a requirement at compile-time (unlike assert, which is runtime).  */
+#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
+
+verify (time_t_is_integer, TYPE_IS_INTEGER (time_t));
+verify (twos_complement_arithmetic, TYPE_TWOS_COMPLEMENT (int));
+/* The code also assumes that signed integer overflow silently wraps
+   around, but this assumption can't be stated without causing a
+   diagnostic on some hosts.  */
+
+#define EPOCH_YEAR 1970
+#define TM_YEAR_BASE 1900
+verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
+
+/* Return 1 if YEAR + TM_YEAR_BASE is a leap year.  */
+static inline int
+leapyear (long int year)
+{
+  /* Don't add YEAR to TM_YEAR_BASE, as that might overflow.
+     Also, work even if YEAR is negative.  */
+  return
+    ((year & 3) == 0
+     && (year % 100 != 0
+         || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3)));
+}
+
+/* How many days come before each month (0-12).  */
+#ifndef _LIBC
+static
+#endif
+const unsigned short int __mon_yday[2][13] =
+  {
+    /* Normal years.  */
+    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
+    /* Leap years.  */
+    { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
+  };
+
+
+#ifndef _LIBC
+/* Portable standalone applications should supply a <time.h> that
+   declares a POSIX-compliant localtime_r, for the benefit of older
+   implementations that lack localtime_r or have a nonstandard one.
+   See the gnulib time_r module for one way to implement this.  */
+# undef __localtime_r
+# define __localtime_r localtime_r
+# define __mktime_internal mktime_internal
+#endif
+
+/* Return an integer value measuring (YEAR1-YDAY1 HOUR1:MIN1:SEC1) -
+   (YEAR0-YDAY0 HOUR0:MIN0:SEC0) in seconds, assuming that the clocks
+   were not adjusted between the time stamps.
+
+   The YEAR values uses the same numbering as TP->tm_year.  Values
+   need not be in the usual range.  However, YEAR1 must not be less
+   than 2 * INT_MIN or greater than 2 * INT_MAX.
+
+   The result may overflow.  It is the caller's responsibility to
+   detect overflow.  */
+
+static inline time_t
+ydhms_diff (long int year1, long int yday1, int hour1, int min1, int sec1,
+            int year0, int yday0, int hour0, int min0, int sec0)
+{
+  verify (C99_integer_division, -1 / 2 == 0);
+  verify (long_int_year_and_yday_are_wide_enough,
+          INT_MAX <= LONG_MAX / 2 || TIME_T_MAX <= UINT_MAX);
+
+  /* Compute intervening leap days correctly even if year is negative.
+     Take care to avoid integer overflow here.  */
+  int a4 = SHR (year1, 2) + SHR (TM_YEAR_BASE, 2) - ! (year1 & 3);
+  int b4 = SHR (year0, 2) + SHR (TM_YEAR_BASE, 2) - ! (year0 & 3);
+  int a100 = a4 / 25 - (a4 % 25 < 0);
+  int b100 = b4 / 25 - (b4 % 25 < 0);
+  int a400 = SHR (a100, 2);
+  int b400 = SHR (b100, 2);
+  int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
+
+  /* Compute the desired time in time_t precision.  Overflow might
+     occur here.  */
+  time_t tyear1 = year1;
+  time_t years = tyear1 - year0;
+  time_t days = 365 * years + yday1 - yday0 + intervening_leap_days;
+  time_t hours = 24 * days + hour1 - hour0;
+  time_t minutes = 60 * hours + min1 - min0;
+  time_t seconds = 60 * minutes + sec1 - sec0;
+  return seconds;
+}
+
+
+/* Return a time_t value corresponding to (YEAR-YDAY HOUR:MIN:SEC),
+   assuming that *T corresponds to *TP and that no clock adjustments
+   occurred between *TP and the desired time.
+   If TP is null, return a value not equal to *T; this avoids false matches.
+   If overflow occurs, yield the minimal or maximal value, except do not
+   yield a value equal to *T.  */
+static time_t
+guess_time_tm (long int year, long int yday, int hour, int min, int sec,
+               const time_t *t, const struct tm *tp)
+{
+  if (tp)
+    {
+      time_t d = ydhms_diff (year, yday, hour, min, sec,
+                             tp->tm_year, tp->tm_yday,
+                             tp->tm_hour, tp->tm_min, tp->tm_sec);
+      time_t t1 = *t + d;
+      if ((t1 < *t) == (TYPE_SIGNED (time_t) ? d < 0 : TIME_T_MAX / 2 < d))
+        return t1;
+    }
+
+  /* Overflow occurred one way or another.  Return the nearest result
+     that is actually in range, except don't report a zero difference
+     if the actual difference is nonzero, as that would cause a false
+     match; and don't oscillate between two values, as that would
+     confuse the spring-forward gap detector.  */
+  return (*t < TIME_T_MIDPOINT
+          ? (*t <= TIME_T_MIN + 1 ? *t + 1 : TIME_T_MIN)
+          : (TIME_T_MAX - 1 <= *t ? *t - 1 : TIME_T_MAX));
+}
+
+/* Use CONVERT to convert *T to a broken down time in *TP.
+   If *T is out of range for conversion, adjust it so that
+   it is the nearest in-range value and then convert that.  */
+static struct tm *
+ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
+                time_t *t, struct tm *tp)
+{
+  struct tm *r = convert (t, tp);
+
+  if (!r && *t)
+    {
+      time_t bad = *t;
+      time_t ok = 0;
+
+      /* BAD is a known unconvertible time_t, and OK is a known good one.
+         Use binary search to narrow the range between BAD and OK until
+         they differ by 1.  */
+      while (bad != ok + (bad < 0 ? -1 : 1))
+        {
+          time_t mid = *t = (bad < 0
+                             ? bad + ((ok - bad) >> 1)
+                             : ok + ((bad - ok) >> 1));
+          r = convert (t, tp);
+          if (r)
+            ok = mid;
+          else
+            bad = mid;
+        }
+
+      if (!r && ok)
+        {
+          /* The last conversion attempt failed;
+             revert to the most recent successful attempt.  */
+          *t = ok;
+          r = convert (t, tp);
+        }
+    }
+
+  return r;
+}
+
+
+/* Convert *TP to a time_t value, inverting
+   the monotonic and mostly-unit-linear conversion function CONVERT.
+   Use *OFFSET to keep track of a guess at the offset of the result,
+   compared to what the result would be for UTC without leap seconds.
+   If *OFFSET's guess is correct, only one CONVERT call is needed.
+   This function is external because it is used also by timegm.c.  */
+time_t
+__mktime_internal (struct tm *tp,
+                   struct tm *(*convert) (const time_t *, struct tm *),
+                   time_t *offset)
+{
+  time_t t, gt, t0, t1, t2;
+  struct tm tm;
+
+  /* The maximum number of probes (calls to CONVERT) should be enough
+     to handle any combinations of time zone rule changes, solar time,
+     leap seconds, and oscillations around a spring-forward gap.
+     POSIX.1 prohibits leap seconds, but some hosts have them anyway.  */
+  int remaining_probes = 6;
+
+  /* Time requested.  Copy it in case CONVERT modifies *TP; this can
+     occur if TP is localtime's returned value and CONVERT is localtime.  */
+  int sec = tp->tm_sec;
+  int min = tp->tm_min;
+  int hour = tp->tm_hour;
+  int mday = tp->tm_mday;
+  int mon = tp->tm_mon;
+  int year_requested = tp->tm_year;
+  /* Normalize the value.  */
+  int isdst = ((tp->tm_isdst >> (8 * sizeof (tp->tm_isdst) - 1))
+               | (tp->tm_isdst != 0));
+
+  /* 1 if the previous probe was DST.  */
+  int dst2;
+
+  /* Ensure that mon is in range, and set year accordingly.  */
+  int mon_remainder = mon % 12;
+  int negative_mon_remainder = mon_remainder < 0;
+  int mon_years = mon / 12 - negative_mon_remainder;
+  long int lyear_requested = year_requested;
+  long int year = lyear_requested + mon_years;
+
+  /* The other values need not be in range:
+     the remaining code handles minor overflows correctly,
+     assuming int and time_t arithmetic wraps around.
+     Major overflows are caught at the end.  */
+
+  /* Calculate day of year from year, month, and day of month.
+     The result need not be in range.  */
+  int mon_yday = ((__mon_yday[leapyear (year)]
+                   [mon_remainder + 12 * negative_mon_remainder])
+                  - 1);
+  long int lmday = mday;
+  long int yday = mon_yday + lmday;
+
+  time_t guessed_offset = *offset;
+
+  int sec_requested = sec;
+
+  if (LEAP_SECONDS_POSSIBLE)
+    {
+      /* Handle out-of-range seconds specially,
+         since ydhms_tm_diff assumes every minute has 60 seconds.  */
+      if (sec < 0)
+        sec = 0;
+      if (59 < sec)
+        sec = 59;
+    }
+
+  /* Invert CONVERT by probing.  First assume the same offset as last
+     time.  */
+
+  t0 = ydhms_diff (year, yday, hour, min, sec,
+                   EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
+
+  if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
+    {
+      /* time_t isn't large enough to rule out overflows, so check
+         for major overflows.  A gross check suffices, since if t0
+         has overflowed, it is off by a multiple of TIME_T_MAX -
+         TIME_T_MIN + 1.  So ignore any component of the difference
+         that is bounded by a small value.  */
+
+      /* Approximate log base 2 of the number of time units per
+         biennium.  A biennium is 2 years; use this unit instead of
+         years to avoid integer overflow.  For example, 2 average
+         Gregorian years are 2 * 365.2425 * 24 * 60 * 60 seconds,
+         which is 63113904 seconds, and rint (log2 (63113904)) is
+         26.  */
+      int ALOG2_SECONDS_PER_BIENNIUM = 26;
+      int ALOG2_MINUTES_PER_BIENNIUM = 20;
+      int ALOG2_HOURS_PER_BIENNIUM = 14;
+      int ALOG2_DAYS_PER_BIENNIUM = 10;
+      int LOG2_YEARS_PER_BIENNIUM = 1;
+
+      int approx_requested_biennia =
+        (SHR (year_requested, LOG2_YEARS_PER_BIENNIUM)
+         - SHR (EPOCH_YEAR - TM_YEAR_BASE, LOG2_YEARS_PER_BIENNIUM)
+         + SHR (mday, ALOG2_DAYS_PER_BIENNIUM)
+         + SHR (hour, ALOG2_HOURS_PER_BIENNIUM)
+         + SHR (min, ALOG2_MINUTES_PER_BIENNIUM)
+         + (LEAP_SECONDS_POSSIBLE
+            ? 0
+            : SHR (sec, ALOG2_SECONDS_PER_BIENNIUM)));
+
+      int approx_biennia = SHR (t0, ALOG2_SECONDS_PER_BIENNIUM);
+      int diff = approx_biennia - approx_requested_biennia;
+      int abs_diff = diff < 0 ? - diff : diff;
+
+      /* IRIX 4.0.5 cc miscaculates TIME_T_MIN / 3: it erroneously
+         gives a positive value of 715827882.  Setting a variable
+         first then doing math on it seems to work.
+         (ghazi@caip.rutgers.edu) */
+      time_t time_t_max = TIME_T_MAX;
+      time_t time_t_min = TIME_T_MIN;
+      time_t overflow_threshold =
+        (time_t_max / 3 - time_t_min / 3) >> ALOG2_SECONDS_PER_BIENNIUM;
+
+      if (overflow_threshold < abs_diff)
+        {
+          /* Overflow occurred.  Try repairing it; this might work if
+             the time zone offset is enough to undo the overflow.  */
+          time_t repaired_t0 = -1 - t0;
+          approx_biennia = SHR (repaired_t0, ALOG2_SECONDS_PER_BIENNIUM);
+          diff = approx_biennia - approx_requested_biennia;
+          abs_diff = diff < 0 ? - diff : diff;
+          if (overflow_threshold < abs_diff)
+            return -1;
+          guessed_offset += repaired_t0 - t0;
+          t0 = repaired_t0;
+        }
+    }
+
+  /* Repeatedly use the error to improve the guess.  */
+
+  for (t = t1 = t2 = t0, dst2 = 0;
+       (gt = guess_time_tm (year, yday, hour, min, sec, &t,
+                            ranged_convert (convert, &t, &tm)),
+        t != gt);
+       t1 = t2, t2 = t, t = gt, dst2 = tm.tm_isdst != 0)
+    if (t == t1 && t != t2
+        && (tm.tm_isdst < 0
+            || (isdst < 0
+                ? dst2 <= (tm.tm_isdst != 0)
+                : (isdst != 0) != (tm.tm_isdst != 0))))
+      /* We can't possibly find a match, as we are oscillating
+         between two values.  The requested time probably falls
+         within a spring-forward gap of size GT - T.  Follow the common
+         practice in this case, which is to return a time that is GT - T
+         away from the requested time, preferring a time whose
+         tm_isdst differs from the requested value.  (If no tm_isdst
+         was requested and only one of the two values has a nonzero
+         tm_isdst, prefer that value.)  In practice, this is more
+         useful than returning -1.  */
+      goto offset_found;
+    else if (--remaining_probes == 0)
+      return -1;
+
+  /* We have a match.  Check whether tm.tm_isdst has the requested
+     value, if any.  */
+  if (isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
+    {
+      /* tm.tm_isdst has the wrong value.  Look for a neighboring
+         time with the right value, and use its UTC offset.
+
+         Heuristic: probe the adjacent timestamps in both directions,
+         looking for the desired isdst.  This should work for all real
+         time zone histories in the tz database.  */
+
+      /* Distance between probes when looking for a DST boundary.  In
+         tzdata2003a, the shortest period of DST is 601200 seconds
+         (e.g., America/Recife starting 2000-10-08 01:00), and the
+         shortest period of non-DST surrounded by DST is 694800
+         seconds (Africa/Tunis starting 1943-04-17 01:00).  Use the
+         minimum of these two values, so we don't miss these short
+         periods when probing.  */
+      int stride = 601200;
+
+      /* The longest period of DST in tzdata2003a is 536454000 seconds
+         (e.g., America/Jujuy starting 1946-10-01 01:00).  The longest
+         period of non-DST is much longer, but it makes no real sense
+         to search for more than a year of non-DST, so use the DST
+         max.  */
+      int duration_max = 536454000;
+
+      /* Search in both directions, so the maximum distance is half
+         the duration; add the stride to avoid off-by-1 problems.  */
+      int delta_bound = duration_max / 2 + stride;
+
+      int delta, direction;
+
+      for (delta = stride; delta < delta_bound; delta += stride)
+        for (direction = -1; direction <= 1; direction += 2)
+          {
+            time_t ot = t + delta * direction;
+            if ((ot < t) == (direction < 0))
+              {
+                struct tm otm;
+                ranged_convert (convert, &ot, &otm);
+                if (otm.tm_isdst == isdst)
+                  {
+                    /* We found the desired tm_isdst.
+                       Extrapolate back to the desired time.  */
+                    t = guess_time_tm (year, yday, hour, min, sec, &ot, &otm);
+                    ranged_convert (convert, &t, &tm);
+                    goto offset_found;
+                  }
+              }
+          }
+    }
+
+ offset_found:
+  *offset = guessed_offset + t - t0;
+
+  if (LEAP_SECONDS_POSSIBLE && sec_requested != tm.tm_sec)
+    {
+      /* Adjust time to reflect the tm_sec requested, not the normalized value.
+         Also, repair any damage from a false match due to a leap second.  */
+      int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
+      t1 = t + sec_requested;
+      t2 = t1 + sec_adjustment;
+      if (((t1 < t) != (sec_requested < 0))
+          | ((t2 < t1) != (sec_adjustment < 0))
+          | ! convert (&t2, &tm))
+        return -1;
+      t = t2;
+    }
+
+  *tp = tm;
+  return t;
+}
+
+
+/* FIXME: This should use a signed type wide enough to hold any UTC
+   offset in seconds.  'int' should be good enough for GNU code.  We
+   can't fix this unilaterally though, as other modules invoke
+   __mktime_internal.  */
+static time_t localtime_offset;
+
+/* Convert *TP to a time_t value.  */
+time_t
+mktime (struct tm *tp)
+{
+#ifdef _LIBC
+  /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
+     time zone names contained in the external variable `tzname' shall
+     be set as if the tzset() function had been called.  */
+  __tzset ();
+#endif
+
+  return __mktime_internal (tp, __localtime_r, &localtime_offset);
+}
+
+#ifdef weak_alias
+weak_alias (mktime, timelocal)
+#endif
+
+#ifdef _LIBC
+libc_hidden_def (mktime)
+libc_hidden_weak (timelocal)
+#endif
+
+#if DEBUG
+
+static int
+not_equal_tm (const struct tm *a, const struct tm *b)
+{
+  return ((a->tm_sec ^ b->tm_sec)
+          | (a->tm_min ^ b->tm_min)
+          | (a->tm_hour ^ b->tm_hour)
+          | (a->tm_mday ^ b->tm_mday)
+          | (a->tm_mon ^ b->tm_mon)
+          | (a->tm_year ^ b->tm_year)
+          | (a->tm_yday ^ b->tm_yday)
+          | (a->tm_isdst ^ b->tm_isdst));
+}
+
+static void
+print_tm (const struct tm *tp)
+{
+  if (tp)
+    printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
+            tp->tm_year + TM_YEAR_BASE, tp->tm_mon + 1, tp->tm_mday,
+            tp->tm_hour, tp->tm_min, tp->tm_sec,
+            tp->tm_yday, tp->tm_wday, tp->tm_isdst);
+  else
+    printf ("0");
+}
+
+static int
+check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
+{
+  if (tk != tl || !lt || not_equal_tm (&tmk, lt))
+    {
+      printf ("mktime (");
+      print_tm (lt);
+      printf (")\nyields (");
+      print_tm (&tmk);
+      printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
+      return 1;
+    }
+
+  return 0;
+}
+
+int
+main (int argc, char **argv)
+{
+  int status = 0;
+  struct tm tm, tmk, tml;
+  struct tm *lt;
+  time_t tk, tl, tl1;
+  char trailer;
+
+  if ((argc == 3 || argc == 4)
+      && (sscanf (argv[1], "%d-%d-%d%c",
+                  &tm.tm_year, &tm.tm_mon, &tm.tm_mday, &trailer)
+          == 3)
+      && (sscanf (argv[2], "%d:%d:%d%c",
+                  &tm.tm_hour, &tm.tm_min, &tm.tm_sec, &trailer)
+          == 3))
+    {
+      tm.tm_year -= TM_YEAR_BASE;
+      tm.tm_mon--;
+      tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
+      tmk = tm;
+      tl = mktime (&tmk);
+      lt = localtime (&tl);
+      if (lt)
+        {
+          tml = *lt;
+          lt = &tml;
+        }
+      printf ("mktime returns %ld == ", (long int) tl);
+      print_tm (&tmk);
+      printf ("\n");
+      status = check_result (tl, tmk, tl, lt);
+    }
+  else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
+    {
+      time_t from = atol (argv[1]);
+      time_t by = atol (argv[2]);
+      time_t to = atol (argv[3]);
+
+      if (argc == 4)
+        for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
+          {
+            lt = localtime (&tl);
+            if (lt)
+              {
+                tmk = tml = *lt;
+                tk = mktime (&tmk);
+                status |= check_result (tk, tmk, tl, &tml);
+              }
+            else
+              {
+                printf ("localtime (%ld) yields 0\n", (long int) tl);
+                status = 1;
+              }
+            tl1 = tl + by;
+            if ((tl1 < tl) != (by < 0))
+              break;
+          }
+      else
+        for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
+          {
+            /* Null benchmark.  */
+            lt = localtime (&tl);
+            if (lt)
+              {
+                tmk = tml = *lt;
+                tk = tl;
+                status |= check_result (tk, tmk, tl, &tml);
+              }
+            else
+              {
+                printf ("localtime (%ld) yields 0\n", (long int) tl);
+                status = 1;
+              }
+            tl1 = tl + by;
+            if ((tl1 < tl) != (by < 0))
+              break;
+          }
+    }
+  else
+    printf ("Usage:\
+\t%s YYYY-MM-DD HH:MM:SS [ISDST] # Test given time.\n\
+\t%s FROM BY TO # Test values FROM, FROM+BY, ..., TO.\n\
+\t%s FROM BY TO - # Do not test those values (for benchmark).\n",
+            argv[0], argv[0], argv[0]);
+
+  return status;
+}
+
+#endif /* DEBUG */
+
+/*
+Local Variables:
+compile-command: "gcc -DDEBUG -Wall -W -O -g mktime.c -o mktime"
+End:
+*/