-/* Copyright (C) 1993, 1994 Free Software Foundation, Inc.
- Contributed by Noel Cragg (noel@cs.oberlin.edu), with fixes by
- Michael E. Calwas (calwas@ttd.teradyne.com) and
- Wade Hampton (tasi029@tmn.com).
+/* Convert a 'struct tm' to a time_t value.
+ Copyright (C) 1993-2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Paul Eggert <eggert@twinsun.com>.
+ 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.
-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 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
+ Lesser General Public License for more details.
-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,
-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, 675 Mass Ave, Cambridge, MA 02139, 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 */
+/* #define DEBUG 1 */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
-#ifdef HAVE_CONFIG_H
-#include <config.h>
+/* 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 <sys/types.h> /* Some systems define `time_t' here. */
#include <time.h>
+#include <limits.h>
-#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))
+#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. */
+# undef mktime
+# define mktime my_mktime
+#endif /* DEBUG */
+
+/* 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 WRAPV 0
+# endif
#endif
-#ifndef __P
-#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
-#define __P(args) args
+/* 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
-#define __P(args) ()
-#endif /* GCC. */
-#endif /* Not __P. */
+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)
+#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 (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 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 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 are in each month. */
-const unsigned short int __mon_lengths[2][12] =
+/* How many days come before each month (0-12). */
+#ifndef _LIBC
+static
+#endif
+const unsigned short int __mon_yday[2][13] =
{
/* Normal years. */
- { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+ { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
/* Leap years. */
- { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+ { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }
};
-static int times_through_search; /* This library routine should never
- hang -- make sure we always return
- when we're searching for a value */
+#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
+/* 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)
+{
+ return (!a != !b) && (0 <= a) && (0 <= b);
+}
-#ifdef DEBUG
+/* 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.
-#include <stdio.h>
-#include <ctype.h>
+ 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.
-int debugging_enabled = 0;
+ The result may overflow. It is the caller's responsibility to
+ detect overflow. */
-/* Print the values in a `struct tm'. */
-static void
-printtm (it)
- struct tm *it;
+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)
{
- printf ("%02d/%02d/%04d %02d:%02d:%02d (%s) yday:%03d dst:%d gmtoffset:%ld",
- it->tm_mon + 1,
- it->tm_mday,
- it->tm_year + 1900,
- it->tm_hour,
- it->tm_min,
- it->tm_sec,
- it->tm_zone,
- it->tm_yday,
- it->tm_isdst,
- it->tm_gmtoff);
+ 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;
}
-#endif
-
+/* Return the average of A and B, even if A + B would overflow. */
static time_t
-dist_tm (t1, t2)
- struct tm *t1;
- struct tm *t2;
+time_t_avg (time_t a, time_t b)
{
- time_t distance = 0;
- unsigned long int v1, v2;
- int diff_flag = 0;
-
- v1 = v2 = 0;
-
-#define doit(x, secs) \
- v1 += t1->x * secs; \
- v2 += t2->x * secs; \
- if (!diff_flag) \
- { \
- if (t1->x < t2->x) \
- diff_flag = -1; \
- else if (t1->x > t2->x) \
- diff_flag = 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);
}
-
- doit (tm_year, 31536000); /* Okay, not all years have 365 days. */
- doit (tm_mon, 2592000); /* Okay, not all months have 30 days. */
- doit (tm_mday, 86400);
- doit (tm_hour, 3600);
- doit (tm_min, 60);
- doit (tm_sec, 1);
-
-#undef doit
-
- /* We should also make sure that the sign of DISTANCE is correct -- if
- DIFF_FLAG is positive, the distance should be positive and vice versa. */
-
- distance = (v1 > v2) ? (v1 - v2) : (v2 - v1);
- if (diff_flag < 0)
- distance = -distance;
-
- if (times_through_search > 20) /* Arbitrary # of calls, but makes sure we
- never hang if there's a problem with
- this algorithm. */
+ else if (WRAPV)
{
- distance = diff_flag;
+ time_t sum = a + b;
+ return (sum < a) == (b < 0);
+ }
+ else
+ {
+ time_t avg = time_t_avg (a, b);
+ return TIME_T_MIN / 2 <= avg && avg <= TIME_T_MAX / 2;
}
-
- /* We need this DIFF_FLAG business because it is forseeable that the
- distance may be zero when, in actuality, the two structures are
- different. This is usually the case when the dates are 366 days apart
- and one of the years is a leap year. */
-
- if (distance == 0 && diff_flag)
- distance = 86400 * diff_flag;
-
- return distance;
}
-
-
-/* MKTIME converts the values in a struct tm to a time_t. The values
- in tm_wday and tm_yday are ignored; other values can be put outside
- of legal ranges since they will be normalized. This routine takes
- care of that normalization. */
-void
-do_normalization (tmptr)
- struct tm *tmptr;
+/* Return 1 if A + B does not overflow. */
+static int
+time_t_int_add_ok (time_t a, int b)
{
-
-#define normalize(foo,x,y,bar); \
- while (tmptr->foo < x) \
- { \
- tmptr->bar--; \
- tmptr->foo = (y - (x - tmptr->foo) + 1); \
- } \
- while (tmptr->foo > y) \
- { \
- tmptr->foo = (x + (tmptr->foo - y) - 1); \
- tmptr->bar++; \
+ verify (int_no_wider_than_time_t, INT_MAX <= TIME_T_MAX);
+ if (WRAPV)
+ {
+ time_t sum = a + b;
+ return (sum < a) == (b < 0);
}
-
- normalize (tm_sec, 0, 59, tm_min);
- normalize (tm_min, 0, 59, tm_hour);
- normalize (tm_hour, 0, 23, tm_mday);
-
- /* Do the month first, so day range can be found. */
- normalize (tm_mon, 0, 11, tm_year);
-
- /* Since the day range modifies the month, we should be careful how
- we reference the array of month lengths -- it is possible that
- the month will go negative, hence the modulo...
-
- Also, tm_year is the year - 1900, so we have to 1900 to have it
- work correctly. */
-
- normalize (tm_mday, 1,
- __mon_lengths[__isleap (tmptr->tm_year + 1900)]
- [((tmptr->tm_mon < 0)
- ? (12 + (tmptr->tm_mon % 12))
- : (tmptr->tm_mon % 12)) ],
- tm_mon);
-
- /* Do the month again, because the day may have pushed it out of range. */
- normalize (tm_mon, 0, 11, tm_year);
-
- /* Do the day again, because the month may have changed the range. */
- normalize (tm_mday, 1,
- __mon_lengths[__isleap (tmptr->tm_year + 1900)]
- [((tmptr->tm_mon < 0)
- ? (12 + (tmptr->tm_mon % 12))
- : (tmptr->tm_mon % 12)) ],
- tm_mon);
-
-#ifdef DEBUG
- if (debugging_enabled)
+ else
{
- printf (" After normalizing:\n ");
- printtm (tmptr);
- putchar ('\n');
+ 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;
}
-#endif
-
}
+/* 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);
+ if (time_t_add_ok (*t, d))
+ return *t + d;
+ }
-/* Here's where the work gets done. */
-
-#define BAD_STRUCT_TM ((time_t) -1)
+ /* 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));
+}
-time_t
-_mktime_internal (timeptr, producer)
- struct tm *timeptr;
- struct tm *(*producer) __P ((const time_t *));
+/* 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 our_tm; /* our working space */
- struct tm *me = &our_tm; /* a pointer to the above */
- time_t result; /* the value we return */
+ struct tm *r = convert (t, tp);
- *me = *timeptr; /* copy the struct tm that was passed
- in by the caller */
+ 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 = time_t_avg (ok, bad);
+ r = convert (t, tp);
+ if (r)
+ ok = mid;
+ else
+ bad = mid;
+ }
- /***************************/
- /* Normalize the structure */
- /***************************/
+ if (!r && ok)
+ {
+ /* The last conversion attempt failed;
+ revert to the most recent successful attempt. */
+ *t = ok;
+ r = convert (t, tp);
+ }
+ }
- /* This routine assumes that the value of TM_ISDST is -1, 0, or 1.
- If the user didn't pass it in that way, fix it. */
+ return r;
+}
- if (me->tm_isdst > 0)
- me->tm_isdst = 1;
- else if (me->tm_isdst < 0)
- me->tm_isdst = -1;
- do_normalization (me);
+/* 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;
+ 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;
+ 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;
+ }
- /* Get out of here if it's not possible to represent this struct.
- If any of the values in the normalized struct tm are negative,
- our algorithms won't work. Luckily, we only need to check the
- year at this point; normalization guarantees that all values will
- be in correct ranges EXCEPT the year. */
+ /* Invert CONVERT by probing. First assume the same offset as last
+ time. */
- if (me->tm_year < 0)
- return BAD_STRUCT_TM;
+ t0 = ydhms_diff (year, yday, hour, min, sec,
+ EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, - guessed_offset);
- /*************************************************/
- /* Find the appropriate time_t for the structure */
- /*************************************************/
+ 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;
+ }
+ }
- /* Modified b-search -- make intelligent guesses as to where the
- time might lie along the timeline, assuming that our target time
- lies a linear distance (w/o considering time jumps of a
- particular region).
+ /* 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_differ (isdst, 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)
+ if (time_t_int_add_ok (t, delta * direction))
+ {
+ time_t ot = t + delta * direction;
+ struct tm otm;
+ ranged_convert (convert, &ot, &otm);
+ if (! isdst_differ (isdst, otm.tm_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;
+ }
+ }
+ }
- Assume that time does not fluctuate at all along the timeline --
- e.g., assume that a day will always take 86400 seconds, etc. --
- and come up with a hypothetical value for the time_t
- representation of the struct tm TARGET, in relation to the guess
- variable -- it should be pretty close!
+ offset_found:
+ *offset = guessed_offset + t - t0;
- After testing this, the maximum number of iterations that I had
- on any number that I tried was 3! Not bad.
+ 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;
+ 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;
+ }
- The reason this is not a subroutine is that we will modify some
- fields in the struct tm (yday and mday). I've never felt good
- about side-effects when writing structured code... */
+ *tp = tm;
+ return t;
+}
- {
- struct tm *guess_tm;
- time_t guess = 0;
- time_t distance = 0;
- time_t last_distance = 0;
-
- times_through_search = 0;
-
- do
- {
- guess += distance;
-
- times_through_search++;
-
- guess_tm = (*producer) (&guess);
-
-#ifdef DEBUG
- if (debugging_enabled)
- {
- printf (" Guessing time_t == %d\n ", (int) guess);
- printtm (guess_tm);
- putchar ('\n');
- }
-#endif
-
- /* How far is our guess from the desired struct tm? */
- distance = dist_tm (me, guess_tm);
-
- /* Handle periods of time where a period of time is skipped.
- For example, 2:15 3 April 1994 does not exist, because DST
- is in effect. The distance function will alternately
- return values of 3600 and -3600, because it doesn't know
- that the requested time doesn't exist. In these situations
- (even if the skip is not exactly an hour) the distances
- returned will be the same, but alternating in sign. We
- want the later time, so check to see that the distance is
- oscillating and we've chosen the correct of the two
- possibilities.
-
- Useful: 3 Apr 94 765356300, 30 Oct 94 783496000 */
-
- if ((distance == -last_distance) && (distance < last_distance))
- {
- /* If the caller specified that the DST flag was off, it's
- not possible to represent this time. */
- if (me->tm_isdst == 0)
- {
-#ifdef DEBUG
- printf (" Distance is oscillating -- dst flag nixes struct!\n");
-#endif
- return BAD_STRUCT_TM;
- }
-#ifdef DEBUG
- printf (" Distance is oscillating -- chose the later time.\n");
-#endif
- distance = 0;
- }
+/* 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 ((distance == 0) && (me->tm_isdst != -1)
- && (me->tm_isdst != guess_tm->tm_isdst))
- {
- /* If we're in this code, we've got the right time but the
- wrong daylight savings flag. We need to move away from
- the time that we have and approach the other time from
- the other direction. That is, if I've requested the
- non-DST version of a time and I get the DST version
- instead, I want to put us forward in time and search
- backwards to get the other time. I checked all of the
- configuration files for the tz package -- no entry
- saves more than two hours, so I think we'll be safe by
- moving 24 hours in one direction. IF THE AMOUNT OF
- TIME SAVED IN THE CONFIGURATION FILES CHANGES, THIS
- VALUE MAY NEED TO BE ADJUSTED. Luckily, we can never
- have more than one level of overlaps, or this would
- never work. */
-
-#define SKIP_VALUE 86400
-
- if (guess_tm->tm_isdst == 0)
- /* we got the later one, but want the earlier one */
- distance = -SKIP_VALUE;
- else
- distance = SKIP_VALUE;
-
-#ifdef DEBUG
- printf (" Got the right time, wrong DST value -- adjusting\n");
+/* 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
- }
- last_distance = distance;
-
- } while (distance != 0);
-
- /* Check to see that the dst flag matches */
+ return __mktime_internal (tp, __localtime_r, &localtime_offset);
+}
- if (me->tm_isdst != -1)
- {
- if (me->tm_isdst != guess_tm->tm_isdst)
- {
-#ifdef DEBUG
- printf (" DST flag doesn't match! FIXME?\n");
+#ifdef weak_alias
+weak_alias (mktime, timelocal)
#endif
- return BAD_STRUCT_TM;
- }
- }
-
- result = guess; /* Success! */
-
- /* On successful completion, the values of tm_wday and tm_yday
- have to be set appropriately. */
-
- /* me->tm_yday = guess_tm->tm_yday;
- me->tm_mday = guess_tm->tm_mday; */
-
- *me = *guess_tm;
- }
- /* Update the caller's version of the structure */
-
- *timeptr = *me;
+#ifdef _LIBC
+libc_hidden_def (mktime)
+libc_hidden_weak (timelocal)
+#endif
+\f
+#if DEBUG
- return result;
+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)
+ | isdst_differ (a->tm_isdst, b->tm_isdst));
}
-time_t
-#ifdef DEBUG /* make it work even if the system's
- libc has it's own mktime routine */
-my_mktime (timeptr)
-#else
-mktime (timeptr)
-#endif
- struct tm *timeptr;
+static void
+print_tm (const struct tm *tp)
{
- return _mktime_internal (timeptr, localtime);
+ 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");
}
-\f
-#ifdef DEBUG
-void
-main (argc, argv)
- int argc;
- char *argv[];
+
+static int
+check_result (time_t tk, struct tm tmk, time_t tl, const struct tm *lt)
{
- int time;
- int result_time;
- struct tm *tmptr;
-
- if (argc == 1)
+ if (tk != tl || !lt || not_equal_tm (&tmk, lt))
{
- long q;
-
- printf ("starting long test...\n");
+ 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;
+}
- for (q = 10000000; q < 1000000000; q += 599)
+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)
{
- struct tm *tm = localtime ((time_t *) &q);
- if ((q % 10000) == 0) { printf ("%ld\n", q); fflush (stdout); }
- if (q != my_mktime (tm))
- { printf ("failed for %ld\n", q); fflush (stdout); }
+ tml = *lt;
+ lt = &tml;
}
-
- printf ("test finished\n");
-
- exit (0);
+ printf ("mktime returns %ld == ", (long int) tl);
+ print_tm (&tmk);
+ printf ("\n");
+ status = check_result (tl, tmk, tl, lt);
}
-
- if (argc != 2)
+ else if (argc == 4 || (argc == 5 && strcmp (argv[4], "-") == 0))
{
- printf ("wrong # of args\n");
- exit (0);
- }
-
- debugging_enabled = 1; /* We want to see the info */
-
- ++argv;
- time = atoi (*argv);
-
- tmptr = localtime ((time_t *) &time);
- printf ("Localtime tells us that a time_t of %d represents\n ", time);
- printtm (tmptr);
- putchar ('\n');
-
- printf (" Given localtime's return val, mktime returns %d which is\n ",
- (int) my_mktime (tmptr));
- printtm (tmptr);
- putchar ('\n');
-
-#if 0
- tmptr->tm_sec -= 20;
- tmptr->tm_min -= 20;
- tmptr->tm_hour -= 20;
- tmptr->tm_mday -= 20;
- tmptr->tm_mon -= 20;
- tmptr->tm_year -= 20;
- tmptr->tm_gmtoff -= 20000; /* This has no effect! */
- tmptr->tm_zone = NULL; /* Nor does this! */
- tmptr->tm_isdst = -1;
-#endif
-
- tmptr->tm_hour += 1;
- tmptr->tm_isdst = -1;
-
- printf ("\n\nchanged ranges: ");
- printtm (tmptr);
- putchar ('\n');
-
- result_time = my_mktime (tmptr);
- printf ("\nmktime: %d\n", result_time);
+ time_t from = atol (argv[1]);
+ time_t by = atol (argv[2]);
+ time_t to = atol (argv[3]);
- tmptr->tm_isdst = 0;
-
- printf ("\n\nchanged ranges: ");
- printtm (tmptr);
- putchar ('\n');
-
- result_time = my_mktime (tmptr);
- printf ("\nmktime: %d\n", result_time);
+ 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 */
+#endif /* DEBUG */
\f
/*
Local Variables:
-compile-command: "gcc -g mktime.c -o mktime -DDEBUG"
+compile-command: "gcc -DDEBUG -I. -Wall -W -O2 -g mktime.c -o mktime"
End:
*/
projects / gnulib.git / blobdiff