| /* Convert a `struct tm' to a time_t value. |
| Copyright (C) 1993-1999, 2002, 2003, 2004 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. |
| |
| 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. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| /* Define this to have a standalone program to test this implementation of |
| mktime. */ |
| /* #define DEBUG 1 */ |
| |
| #ifdef HAVE_CONFIG_H |
| # 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 <sys/types.h> /* Some systems define `time_t' here. */ |
| #include <time.h> |
| |
| #include <limits.h> |
| #include <string.h> /* For string function builtin redirect. */ |
| |
| #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 */ |
| |
| /* 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 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 |
| |
| /* 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, (time_t) 0.5 == 0); |
| verify (twos_complement_arithmetic, -1 == ~1 + 1); |
| verify (right_shift_propagates_sign, -1 >> 1 == -1); |
| /* 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); |
| |
| #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 |
| |
| /* 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_r.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. */ |
| # include "time_r.h" |
| # undef __localtime_r |
| # define __localtime_r localtime_r |
| #endif |
| |
| |
| /* 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. */ |
| static time_t |
| ydhms_tm_diff (int year, int yday, int hour, int min, int sec, |
| const struct tm *tp) |
| { |
| if (!tp) |
| return 1; |
| else |
| { |
| verify (C99_integer_division, -1 / 2 == 0); |
| |
| /* 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)); |
| } |
| } |
| |
| /* 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; |
| |
| 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 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. */ |
| time_t |
| __mktime_internal (struct tm *tp, |
| struct tm *(*convert) (const time_t *, struct tm *), |
| time_t *offset) |
| { |
| 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, |
| 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; |
| int year = year_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 yday = ((__mon_yday[__isleap (year + TM_YEAR_BASE)] |
| [mon_remainder + 12 * negative_mon_remainder]) |
| + 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. */ |
| 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. */ |
| |
| 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); |
| |
| 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; |
| |
| /* 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) |
| { |
| /* 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++) |
| { |
| time_t ot = t - i * quarter; |
| 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 = ot + ydhms_tm_diff (year, yday, hour, min, sec, &otm); |
| ranged_convert (convert, &t, &tm); |
| break; |
| } |
| } |
| } |
| |
| *offset = t - t0; |
| |
| #if LEAP_SECONDS_POSSIBLE |
| if (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)) |
| return -1; |
| } |
| #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; |
| |
| /* 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; |
| } |
| |
| *tp = tm; |
| return t; |
| } |
| |
| |
| 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_mday ^ b->tm_mday) |
| | (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 -DHAVE_TIME_R_POSIX -Wall -W -O -g mktime.c -o mktime" |
| End: |
| */ |