-/* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
+/* Convert a `struct tm' to a time_t value.
+ Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2002, 2003, 2004,
+ 2005 Free Software Foundation, Inc.
Contributed by Paul Eggert (eggert@twinsun.com).
NOTE: The canonical source of this file is maintained with the GNU C Library.
- Bugs can be reported to bug-glibc@prep.ai.mit.edu.
+ Bugs can be reported to bug-glibc@gnu.org.
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
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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
USA. */
/* Define this to have a standalone program to test this implementation of
#ifdef _LIBC
# define HAVE_LIMITS_H 1
-# define HAVE_LOCALTIME_R 1
# define STDC_HEADERS 1
#endif
#endif /* DEBUG */
#ifndef __P
-# if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
+# if defined __GNUC__ || (defined __STDC__ && __STDC__)
# define __P(args) args
# else
# define __P(args) ()
# define CHAR_BIT 8
#endif
+/* The extra casts work around common compiler bugs. */
+#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1))
+/* The outer cast is needed to work around a bug in Cray C 5.0.3.0.
+ It is necessary at least when t == time_t. */
+#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \
+ ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0))
+#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t)))
+
#ifndef INT_MIN
-# define INT_MIN (~0 << (sizeof (int) * CHAR_BIT - 1))
+# define INT_MIN TYPE_MINIMUM (int)
#endif
#ifndef INT_MAX
-# define INT_MAX (~0 - INT_MIN)
+# define INT_MAX TYPE_MAXIMUM (int)
#endif
#ifndef TIME_T_MIN
-/* The outer cast to time_t works around a bug in Cray C 5.0.3.0. */
-# define TIME_T_MIN ((time_t) \
- (0 < (time_t) -1 ? (time_t) 0 \
- : ~ (time_t) 0 << (sizeof (time_t) * CHAR_BIT - 1)))
+# define TIME_T_MIN TYPE_MINIMUM (time_t)
#endif
#ifndef TIME_T_MAX
-# define TIME_T_MAX (~ (time_t) 0 - TIME_T_MIN)
+# define TIME_T_MAX TYPE_MAXIMUM (time_t)
#endif
#define TM_YEAR_BASE 1900
{ 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
-static time_t ydhms_tm_diff __P ((int, int, int, int, int, const struct tm *));
-time_t __mktime_internal __P ((struct tm *,
- struct tm *(*) (const time_t *, struct tm *),
- time_t *));
-
#ifdef _LIBC
-# define localtime_r __localtime_r
+# define my_mktime_localtime_r __localtime_r
#else
-# if ! HAVE_LOCALTIME_R && ! defined localtime_r
-/* Approximate localtime_r as best we can in its absence. */
-# define localtime_r my_mktime_localtime_r
-static struct tm *localtime_r __P ((const time_t *, struct tm *));
+/* If we're a mktime substitute in a GNU program, then prefer
+ localtime to localtime_r, since many localtime_r implementations
+ are buggy. */
static struct tm *
-localtime_r (t, tp)
+my_mktime_localtime_r (t, tp)
const time_t *t;
struct tm *tp;
{
*tp = *l;
return tp;
}
-# endif /* ! HAVE_LOCALTIME_R && ! defined (localtime_r) */
#endif /* ! _LIBC */
measured in seconds, ignoring leap seconds.
YEAR uses the same numbering as TM->tm_year.
All values are in range, except possibly YEAR.
+ If TP is null, return a nonzero value.
If overflow occurs, yield the low order bits of the correct answer. */
static time_t
ydhms_tm_diff (year, yday, hour, min, sec, tp)
int year, yday, hour, min, sec;
const struct tm *tp;
{
- /* Compute intervening leap days correctly even if year is negative.
- Take care to avoid int overflow. time_t overflow is OK, since
- only the low order bits of the correct time_t answer are needed.
- Don't convert to time_t until after all divisions are done, since
- time_t might be unsigned. */
- int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - ! (year & 3);
- int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (tp->tm_year & 3);
- int a100 = a4 / 25 - (a4 % 25 < 0);
- int b100 = b4 / 25 - (b4 % 25 < 0);
- int a400 = a100 >> 2;
- int b400 = b100 >> 2;
- int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
- time_t years = year - (time_t) tp->tm_year;
- time_t days = (365 * years + intervening_leap_days
- + (yday - tp->tm_yday));
- return (60 * (60 * (24 * days + (hour - tp->tm_hour))
- + (min - tp->tm_min))
- + (sec - tp->tm_sec));
+ if (!tp)
+ return 1;
+ else
+ {
+ /* Compute intervening leap days correctly even if year is negative.
+ Take care to avoid int overflow. time_t overflow is OK, since
+ only the low order bits of the correct time_t answer are needed.
+ Don't convert to time_t until after all divisions are done, since
+ time_t might be unsigned. */
+ int a4 = (year >> 2) + (TM_YEAR_BASE >> 2) - ! (year & 3);
+ int b4 = (tp->tm_year >> 2) + (TM_YEAR_BASE >> 2) - ! (tp->tm_year & 3);
+ int a100 = a4 / 25 - (a4 % 25 < 0);
+ int b100 = b4 / 25 - (b4 % 25 < 0);
+ int a400 = a100 >> 2;
+ int b400 = b100 >> 2;
+ int intervening_leap_days = (a4 - b4) - (a100 - b100) + (a400 - b400);
+ time_t years = year - (time_t) tp->tm_year;
+ time_t days = (365 * years + intervening_leap_days
+ + (yday - tp->tm_yday));
+ return (60 * (60 * (24 * days + (hour - tp->tm_hour))
+ + (min - tp->tm_min))
+ + (sec - tp->tm_sec));
+ }
}
-
-static time_t localtime_offset;
-
-/* Convert *TP to a time_t value. */
-time_t
-mktime (tp)
+/* 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 (convert, t, tp)
+#ifdef PROTOTYPES
+ struct tm *(*convert) (const time_t *, struct tm *);
+#else
+ struct tm *(*convert)();
+#endif
+ time_t *t;
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
+ struct tm *r;
+
+ if (! (r = (*convert) (t, tp)) && *t)
+ {
+ time_t bad = *t;
+ time_t ok = 0;
+ struct tm tm;
+
+ /* 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));
+ if ((r = (*convert) (t, tp)))
+ {
+ tm = *r;
+ ok = mid;
+ }
+ else
+ bad = mid;
+ }
+
+ if (!r && ok)
+ {
+ /* The last conversion attempt failed;
+ revert to the most recent successful attempt. */
+ *t = ok;
+ *tp = tm;
+ r = tp;
+ }
+ }
- return __mktime_internal (tp, localtime_r, &localtime_offset);
+ 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,
time_t
__mktime_internal (tp, convert, offset)
struct tm *tp;
- struct tm *(*convert) __P ((const time_t *, struct tm *));
+#ifdef PROTOTYPES
+ struct tm *(*convert) (const time_t *, struct tm *);
+#else
+ struct tm *(*convert)();
+#endif
time_t *offset;
{
- time_t t, dt, t0;
+ time_t t, dt, 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,
- and leap seconds. Posix.1 prohibits leap seconds, but some hosts
- have them anyway. */
- int remaining_probes = 4;
+ 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 year_requested = tp->tm_year;
int isdst = tp->tm_isdst;
+ /* 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;
+ mday - 1);
int sec_requested = sec;
+
+ /* Only years after 1970 are defined.
+ If year is 69, it might still be representable due to
+ timezone differences. */
+ if (year < 69)
+ return -1;
+
#if LEAP_SECONDS_POSSIBLE
/* Handle out-of-range seconds specially,
since ydhms_tm_diff assumes every minute has 60 seconds. */
tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm);
- for (t = t0 + *offset;
- (dt = ydhms_tm_diff (year, yday, hour, min, sec, (*convert) (&t, &tm)));
- t += dt)
- if (--remaining_probes == 0)
+ for (t = t1 = t2 = t0 + *offset, dst2 = 0;
+ (dt = ydhms_tm_diff (year, yday, hour, min, sec,
+ ranged_convert (convert, &t, &tm)));
+ t1 = t2, t2 = t, t += dt, 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 DT. Follow the common
+ practice in this case, which is to return a time that is DT
+ 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. */
+ break;
+ else if (--remaining_probes == 0)
return -1;
- /* Check whether tm.tm_isdst has the requested value, if any. */
- if (0 <= isdst && 0 <= tm.tm_isdst)
+ /* If we have a match, check whether tm.tm_isdst has the requested
+ value, if any. */
+ if (dt == 0 && isdst != tm.tm_isdst && 0 <= isdst && 0 <= tm.tm_isdst)
{
- int dst_diff = (isdst != 0) - (tm.tm_isdst != 0);
- if (dst_diff)
+ /* tm.tm_isdst has the wrong value. Look for a neighboring
+ time with the right value, and use its UTC offset.
+ Heuristic: probe the previous three calendar quarters (approximately),
+ looking for the desired isdst. This isn't perfect,
+ but it's good enough in practice. */
+ int quarter = 7889238; /* seconds per average 1/4 Gregorian year */
+ int i;
+
+ /* If we're too close to the time_t limit, look in future quarters. */
+ if (t < TIME_T_MIN + 3 * quarter)
+ quarter = -quarter;
+
+ for (i = 1; i <= 3; i++)
{
- /* Move two hours in the direction indicated by the disagreement,
- probe some more, and switch to a new time if found.
- The largest known fallback due to daylight savings is two hours:
- once, in Newfoundland, 1988-10-30 02:00 -> 00:00. */
- time_t ot = t - 2 * 60 * 60 * dst_diff;
- while (--remaining_probes != 0)
+ time_t ot = t - i * quarter;
+ struct tm otm;
+ ranged_convert (convert, &ot, &otm);
+ if (otm.tm_isdst == isdst)
{
- struct tm otm;
- if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec,
- (*convert) (&ot, &otm))))
- {
- t = ot;
- tm = otm;
- break;
- }
- if ((ot += dt) == t)
- break; /* Avoid a redundant probe. */
+ /* We found the desired tm_isdst.
+ Extrapolate back to the desired time. */
+ t = ot + ydhms_tm_diff (year, yday, hour, min, sec, &otm);
+ ranged_convert (convert, &t, &tm);
+ break;
}
}
}
/* 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. */
t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60);
- (*convert) (&t, &tm);
+ if (! (*convert) (&t, &tm))
+ return -1;
}
#endif
double dday = 366 * dyear + mday;
double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
- if (TIME_T_MAX / 3 - TIME_T_MIN / 3 < (dsec < 0 ? - dsec : dsec))
+ /* On Irix4.0.5 cc, dividing TIME_T_MIN by 3 does not produce
+ correct results, ie., it erroneously gives a positive value
+ of 715827882. Setting a variable first then doing math on it
+ seems to work. (ghazi@caip.rutgers.edu) */
+
+ const time_t time_t_max = TIME_T_MAX;
+ const time_t time_t_min = TIME_T_MIN;
+
+ if (time_t_max / 3 - time_t_min / 3 < (dsec < 0 ? - dsec : dsec))
+ return -1;
+ }
+
+ if (year == 69)
+ {
+ /* If year was 69, need to check whether the time was representable
+ or not. */
+ if (t < 0 || t > 2 * 24 * 60 * 60)
return -1;
}
return t;
}
+
+static time_t localtime_offset;
+
+/* Convert *TP to a time_t value. */
+time_t
+mktime (tp)
+ 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, my_mktime_localtime_r, &localtime_offset);
+}
+
#ifdef weak_alias
weak_alias (mktime, timelocal)
#endif
print_tm (tp)
struct tm *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);
+ 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 (tk, tmk, tl, tml)
+check_result (tk, tmk, tl, lt)
time_t tk;
struct tm tmk;
time_t tl;
- struct tm tml;
+ struct tm *lt;
{
- if (tk != tl || not_equal_tm (&tmk, &tml))
+ if (tk != tl || !lt || not_equal_tm (&tmk, lt))
{
printf ("mktime (");
print_tm (&tmk);
printf (")\nyields (");
- print_tm (&tml);
+ print_tm (lt);
printf (") == %ld, should be %ld\n", (long) tl, (long) tk);
return 1;
}
{
int status = 0;
struct tm tm, tmk, tml;
+ struct tm *lt;
time_t tk, tl;
char trailer;
tm.tm_isdst = argc == 3 ? -1 : atoi (argv[3]);
tmk = tm;
tl = mktime (&tmk);
- tml = *localtime (&tl);
+ lt = localtime (&tl);
+ if (lt)
+ {
+ tml = *lt;
+ lt = &tml;
+ }
printf ("mktime returns %ld == ", (long) tl);
print_tm (&tmk);
printf ("\n");
- status = check_result (tl, tmk, tl, tml);
+ status = check_result (tl, tmk, tl, lt);
}
else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
{
if (argc == 4)
for (tl = from; tl <= to; tl += by)
{
- tml = *localtime (&tl);
- tmk = tml;
- tk = mktime (&tmk);
- status |= check_result (tk, tmk, tl, tml);
+ 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) tl);
+ status = 1;
+ }
}
else
for (tl = from; tl <= to; tl += by)
{
/* Null benchmark. */
- tml = *localtime (&tl);
- tmk = tml;
- tk = tl;
- status |= check_result (tk, tmk, tl, tml);
+ 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) tl);
+ status = 1;
+ }
}
}
else
\f
/*
Local Variables:
-compile-command: "gcc -DDEBUG=1 -Wall -O -g mktime.c -o mktime"
+compile-command: "gcc -DDEBUG -DHAVE_LIMITS_H -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime"
End:
*/
+
+/* arch-tag: 9456752f-7ddd-47cb-8286-fa807b1355ae
+ (do not change this comment) */