-/* mktime: convert a `struct tm' to a time_t value zzzzzz
- Copyright (C) 1993-1997, 1998 Free Software Foundation, Inc.
- Contributed by Paul Eggert (eggert@twinsun.com).
+/* Convert a 'struct tm' to a time_t value.
+ Copyright (C) 1993-2014 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ 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.
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
- 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 2, or (at your option) any
- later version.
-
- This program is distributed in the hope that it will be useful,
+ The GNU C Library 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.
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
- USA. */
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
/* Define this to have a standalone program to test this implementation of
mktime. */
/* #define DEBUG 1 */
-#ifdef HAVE_CONFIG_H
+#ifndef _LIBC
# include <config.h>
#endif
-/* Some systems require that one of these symbols be defined in
- order to declare localtime_r properly. */
-#ifndef __EXTENSIONS__
-# define __EXTENSIONS__ 1
-#endif
-#ifndef _REENTRANT
-# define _REENTRANT 1
-#endif
-
-
-#ifdef _LIBC
-# define HAVE_LIMITS_H 1
-# define HAVE_LOCALTIME_R 1
-# define STDC_HEADERS 1
-#endif
-
/* Assume that leap seconds are possible, unless told otherwise.
- If the host has a `zic' command with a `-L leapsecondfilename' option,
+ 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 <sys/types.h> /* Some systems define `time_t' here. */
#include <time.h>
-#if HAVE_LIMITS_H
-# include <limits.h>
-#endif
+#include <limits.h>
+
+#include <string.h> /* For the real memcpy prototype. */
#if DEBUG
# include <stdio.h>
-# if STDC_HEADERS
-# include <stdlib.h>
-# endif
+# include <stdlib.h>
/* Make it work even if the system's libc has its own mktime routine. */
+# undef mktime
# define mktime my_mktime
#endif /* DEBUG */
-#ifndef __P
-# if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
-# define __P(args) args
+/* Some of the code in this file assumes that signed integer overflow
+ silently wraps around. This assumption can't easily be programmed
+ around, nor can it be checked for portably at compile-time or
+ easily eliminated at run-time.
+
+ Define WRAPV to 1 if the assumption is valid and if
+ #pragma GCC optimize ("wrapv")
+ does not trigger GCC bug 51793
+ <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51793>.
+ Otherwise, define it to 0; this forces the use of slower code that,
+ while not guaranteed by the C Standard, works on all production
+ platforms that we know about. */
+#ifndef WRAPV
+# if (((__GNUC__ == 4 && 4 <= __GNUC_MINOR__) || 4 < __GNUC__) \
+ && defined __GLIBC__)
+# pragma GCC optimize ("wrapv")
+# define WRAPV 1
# else
-# define __P(args) ()
-# endif /* GCC. */
-#endif /* Not __P. */
-
-#ifndef CHAR_BIT
-# define CHAR_BIT 8
+# define WRAPV 0
+# endif
#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 TYPE_MINIMUM (int)
-#endif
-#ifndef INT_MAX
-# define INT_MAX TYPE_MAXIMUM (int)
+/* Verify a requirement at compile-time (unlike assert, which is runtime). */
+#define verify(name, assertion) struct name { char a[(assertion) ? 1 : -1]; }
+
+/* A signed type that is at least one bit wider than int. */
+#if INT_MAX <= LONG_MAX / 2
+typedef long int long_int;
+#else
+typedef long long int long_int;
#endif
+verify (long_int_is_wide_enough, INT_MAX == INT_MAX * (long_int) 2 / 2);
+
+/* 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 \
+ && (long_int) -1 >> 1 == -1 \
+ && ((time_t) -1 >> 1 == -1 || ! TYPE_SIGNED (time_t))) \
+ ? (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, or if T is an unsigned integer type. */
+#define TYPE_TWOS_COMPLEMENT(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_MAXIMUM (t)))
+#define TYPE_MAXIMUM(t) \
+ ((t) (! TYPE_SIGNED (t) \
+ ? (t) -1 \
+ : ((((t) 1 << (sizeof (t) * CHAR_BIT - 2)) - 1) * 2 + 1)))
#ifndef TIME_T_MIN
# define TIME_T_MIN TYPE_MINIMUM (time_t)
#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 (time_t_is_integer, TYPE_IS_INTEGER (time_t));
+verify (twos_complement_arithmetic,
+ (TYPE_TWOS_COMPLEMENT (int)
+ && TYPE_TWOS_COMPLEMENT (long_int)
+ && TYPE_TWOS_COMPLEMENT (time_t)));
-#define TM_YEAR_BASE 1900
#define EPOCH_YEAR 1970
+#define TM_YEAR_BASE 1900
+verify (base_year_is_a_multiple_of_100, TM_YEAR_BASE % 100 == 0);
-#ifndef __isleap
-/* Nonzero if YEAR is a leap year (every 4 years,
- except every 100th isn't, and every 400th is). */
-# define __isleap(year) \
- ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
-#endif
+/* Return 1 if YEAR + TM_YEAR_BASE is a leap year. */
+static 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, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
-static struct tm *ranged_convert __P ((struct tm *(*) __P ((const time_t *,
- struct tm *)),
- time_t *, struct tm *));
-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 *));
+#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
+# include "mktime-internal.h"
+#endif
-#ifdef _LIBC
-# define localtime_r __localtime_r
-#else
-# if HAVE_LOCALTIME_R == defined (localtime_r)
-/* Provide our own substitute for a missing or possibly broken localtime_r. */
-static struct tm *my_mktime_localtime_r __P ((const time_t *, struct tm *));
-static struct tm *
-my_mktime_localtime_r (t, tp)
- const time_t *t;
- struct tm *tp;
+/* Return 1 if the values A and B differ according to the rules for
+ tm_isdst: A and B differ if one is zero and the other positive. */
+static int
+isdst_differ (int a, int b)
{
-# ifdef localtime_r
- /* Digital Unix 4.0A and 4.0D have a macro localtime_r with the
- standard meaning, along with an unwanted, nonstandard function
- localtime_r. The placeholder function my_mktime_localtime_r
- invokes the macro; use that instead of the system's bogus
- localtime_r. */
- return localtime_r (t, tp);
-# undef localtime_r
-# else /* ! defined (localtime_r) */
- /* Approximate localtime_r as best we can in its absence. */
- struct tm *l = localtime (t);
- if (! l)
- return 0;
- *tp = *l;
- return tp;
-# endif /* ! defined (localtime_r) */
+ return (!a != !b) && (0 <= a) && (0 <= b);
}
-# define localtime_r my_mktime_localtime_r
-# endif /* HAVE_LOCALTIME_R == defined (localtime_r) */
-#endif /* ! _LIBC */
+/* 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 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);
+
+ /* 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;
+}
-/* Yield the difference between (YEAR-YDAY HOUR:MIN:SEC) and (*TP),
- 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. */
+/* Return the average of A and B, even if A + B would overflow. */
static time_t
-ydhms_tm_diff (year, yday, hour, min, sec, tp)
- int year, yday, hour, min, sec;
- const struct tm *tp;
+time_t_avg (time_t a, time_t b)
{
- if (!tp)
- return 1;
+ return SHR (a, 1) + SHR (b, 1) + (a & b & 1);
+}
+
+/* Return 1 if A + B does not overflow. If time_t is unsigned and if
+ B's top bit is set, assume that the sum represents A - -B, and
+ return 1 if the subtraction does not wrap around. */
+static int
+time_t_add_ok (time_t a, time_t b)
+{
+ if (! TYPE_SIGNED (time_t))
+ {
+ time_t sum = a + b;
+ return (sum < a) == (TIME_T_MIDPOINT <= b);
+ }
+ else if (WRAPV)
+ {
+ time_t sum = a + b;
+ return (sum < a) == (b < 0);
+ }
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));
+ time_t avg = time_t_avg (a, b);
+ return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2;
}
}
+/* Return 1 if A + B does not overflow. */
+static int
+time_t_int_add_ok (time_t a, int b)
+{
+ verify (int_no_wider_than_time_t, INT_MAX <= TIME_T_MAX);
+ if (WRAPV)
+ {
+ time_t sum = a + b;
+ return (sum < a) == (b < 0);
+ }
+ else
+ {
+ int a_odd = a & 1;
+ time_t avg = SHR (a, 1) + (SHR (b, 1) + (a_odd & b));
+ return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2;
+ }
+}
-static time_t localtime_offset;
-
-/* Convert *TP to a time_t value. */
-time_t
-mktime (tp)
- struct tm *tp;
+/* 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)
{
-#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
+ 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);
+ if (time_t_add_ok (*t, d))
+ return *t + d;
+ }
- return __mktime_internal (tp, localtime_r, &localtime_offset);
+ /* 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 (convert, t, tp)
- struct tm *(*convert) __P ((const time_t *, struct tm *));
- time_t *t;
- struct tm *tp;
+ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
+ time_t *t, struct tm *tp)
{
- struct tm *r;
+ struct tm *r = convert (t, tp);
- if (! (r = (*convert) (t, tp)) && *t)
+ if (!r && *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;
- }
+ time_t mid = *t = time_t_avg (ok, bad);
+ r = convert (t, tp);
+ if (r)
+ ok = mid;
else
bad = mid;
}
/* The last conversion attempt failed;
revert to the most recent successful attempt. */
*t = ok;
- *tp = tm;
- r = tp;
+ r = convert (t, tp);
}
}
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. */
+ 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 (tp, convert, offset)
- struct tm *tp;
- struct tm *(*convert) __P ((const time_t *, struct tm *));
- time_t *offset;
+__mktime_internal (struct tm *tp,
+ struct tm *(*convert) (const time_t *, struct tm *),
+ time_t *offset)
{
- time_t t, dt, t0, t1, t2;
+ time_t t, gt, t0, t1, t2;
struct tm tm;
/* The maximum number of probes (calls to CONVERT) should be enough
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;
int mon_years = mon / 12 - negative_mon_remainder;
- int year = year_requested + mon_years;
+ 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,
/* Calculate day of year from year, month, and day of month.
The result need not be in range. */
- int yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)]
- [mon_remainder + 12 * negative_mon_remainder])
- + mday - 1);
+ 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;
-#endif
- /* Invert CONVERT by probing. First assume the same offset as last time.
- Then repeatedly use the error to improve the guess. */
+ 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 approx_abs_diff = diff < 0 ? -1 - diff : diff;
+
+ /* IRIX 4.0.5 cc miscalculates 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 < approx_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;
+ approx_abs_diff = diff < 0 ? -1 - diff : diff;
+ if (overflow_threshold < approx_abs_diff)
+ return -1;
+ guessed_offset += repaired_t0 - t0;
+ t0 = repaired_t0;
+ }
+ }
- tm.tm_year = EPOCH_YEAR - TM_YEAR_BASE;
- tm.tm_yday = tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
- t0 = ydhms_tm_diff (year, yday, hour, min, sec, &tm);
+ /* Repeatedly use the error to improve the guess. */
- for (t = t1 = t2 = t0 + *offset;
- (dt = ydhms_tm_diff (year, yday, hour, min, sec,
- ranged_convert (convert, &t, &tm)));
- t1 = t2, t2 = t, t += dt)
+ 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
- && (isdst < 0 || tm.tm_isdst < 0
- || (isdst != 0) != (tm.tm_isdst != 0)))
+ && (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
+ 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. In practice,
- this is more useful than returning -1. */
- break;
+ 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;
- /* If we have a match, check whether tm.tm_isdst has the requested
+ /* We have a match. Check whether tm.tm_isdst has the requested
value, if any. */
- if (dt == 0 && 0 <= isdst && 0 <= tm.tm_isdst)
+ if (isdst_differ (isdst, tm.tm_isdst))
{
- int dst_diff = (isdst != 0) - (tm.tm_isdst != 0);
- if (dst_diff)
- {
- /* 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)
+ /* 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)
+ if (time_t_int_add_ok (t, delta * direction))
{
+ time_t ot = t + delta * direction;
struct tm otm;
- if (! (dt = ydhms_tm_diff (year, yday, hour, min, sec,
- ranged_convert (convert, &ot, &otm))))
+ ranged_convert (convert, &ot, &otm);
+ if (! isdst_differ (isdst, otm.tm_isdst))
{
- t = ot;
- tm = otm;
- break;
+ /* 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;
}
- if ((ot += dt) == t)
- break; /* Avoid a redundant probe. */
}
- }
}
- *offset = t - t0;
+ offset_found:
+ *offset = guessed_offset + t - t0;
-#if LEAP_SECONDS_POSSIBLE
- if (sec_requested != tm.tm_sec)
+ 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. */
- t += sec_requested - sec + (sec == 0 && tm.tm_sec == 60);
- if (! (*convert) (&t, &tm))
+ int sec_adjustment = (sec == 0 && tm.tm_sec == 60) - sec;
+ if (! time_t_int_add_ok (t, sec_requested))
+ return -1;
+ t1 = t + sec_requested;
+ if (! time_t_int_add_ok (t1, sec_adjustment))
+ return -1;
+ t2 = t1 + sec_adjustment;
+ if (! convert (&t2, &tm))
return -1;
+ t = t2;
}
-#endif
-
- if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
- {
- /* time_t isn't large enough to rule out overflows in ydhms_tm_diff,
- so check for major overflows. A gross check suffices,
- since if t 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. */
- double dyear = (double) year_requested + mon_years - tm.tm_year;
- double dday = 366 * dyear + mday;
- double dsec = 60 * (60 * (24 * dday + hour) + min) + sec_requested;
+ *tp = tm;
+ return t;
+}
- /* 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;
+/* 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;
- if (time_t_max / 3 - time_t_min / 3 < (dsec < 0 ? - dsec : dsec))
- return -1;
- }
+/* 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
- *tp = tm;
- return t;
+ 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
\f
#if DEBUG
static int
-not_equal_tm (a, b)
- struct tm *a;
- struct tm *b;
+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_mday ^ b->tm_mday)
| (a->tm_mon ^ b->tm_mon)
| (a->tm_year ^ b->tm_year)
- | (a->tm_mday ^ b->tm_mday)
| (a->tm_yday ^ b->tm_yday)
- | (a->tm_isdst ^ b->tm_isdst));
+ | isdst_differ (a->tm_isdst, b->tm_isdst));
}
static void
-print_tm (tp)
- struct tm *tp;
+print_tm (const struct tm *tp)
{
if (tp)
printf ("%04d-%02d-%02d %02d:%02d:%02d yday %03d wday %d isdst %d",
}
static int
-check_result (tk, tmk, tl, lt)
- time_t tk;
- struct tm tmk;
- time_t tl;
- struct tm *lt;
+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 (&tmk);
- printf (")\nyields (");
print_tm (lt);
- printf (") == %ld, should be %ld\n", (long) tl, (long) tk);
+ printf (")\nyields (");
+ print_tm (&tmk);
+ printf (") == %ld, should be %ld\n", (long int) tk, (long int) tl);
return 1;
}
}
int
-main (argc, argv)
- int argc;
- char **argv;
+main (int argc, char **argv)
{
int status = 0;
struct tm tm, tmk, tml;
struct tm *lt;
- time_t tk, tl;
+ time_t tk, tl, tl1;
char trailer;
if ((argc == 3 || argc == 4)
tml = *lt;
lt = &tml;
}
- printf ("mktime returns %ld == ", (long) tl);
+ printf ("mktime returns %ld == ", (long int) tl);
print_tm (&tmk);
printf ("\n");
status = check_result (tl, tmk, tl, lt);
time_t to = atol (argv[3]);
if (argc == 4)
- for (tl = from; tl <= to; tl += by)
+ 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);
+ status |= check_result (tk, tmk, tl, &tml);
}
else
{
- printf ("localtime (%ld) yields 0\n", (long) tl);
+ printf ("localtime (%ld) yields 0\n", (long int) tl);
status = 1;
}
+ tl1 = tl + by;
+ if ((tl1 < tl) != (by < 0))
+ break;
}
else
- for (tl = from; tl <= to; tl += by)
+ for (tl = from; by < 0 ? to <= tl : tl <= to; tl = tl1)
{
/* Null benchmark. */
lt = localtime (&tl);
{
tmk = tml = *lt;
tk = tl;
- status |= check_result (tk, tmk, tl, tml);
+ status |= check_result (tk, tmk, tl, &tml);
}
else
{
- printf ("localtime (%ld) yields 0\n", (long) tl);
+ printf ("localtime (%ld) yields 0\n", (long int) tl);
status = 1;
}
+ tl1 = tl + by;
+ if ((tl1 < tl) != (by < 0))
+ break;
}
}
else
\f
/*
Local Variables:
-compile-command: "gcc -DDEBUG -D__EXTENSIONS__ -DHAVE_LIMITS_H -DHAVE_LOCALTIME_R -DSTDC_HEADERS -Wall -W -O -g mktime.c -o mktime"
+compile-command: "gcc -DDEBUG -I. -Wall -W -O2 -g mktime.c -o mktime"
End:
*/
projects / gnulib.git / blobdiff