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Diffstat (limited to 'src/gl/mktime.c')
| -rw-r--r-- | src/gl/mktime.c | 630 |
1 files changed, 0 insertions, 630 deletions
diff --git a/src/gl/mktime.c b/src/gl/mktime.c deleted file mode 100644 index 8ee4e5ecab..0000000000 --- a/src/gl/mktime.c +++ /dev/null @@ -1,630 +0,0 @@ -/* Convert a 'struct tm' to a time_t value. - Copyright (C) 1993-2016 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 General Public - License as published by the Free Software Foundation; either - version 3 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 - General Public License for more details. - - You should have received a copy of the GNU General Public - License along with the GNU C Library; if not, see - <http://www.gnu.org/licenses/>. */ - -/* Define this to 1 to have a standalone program to test this implementation of - mktime. */ -#ifndef DEBUG_MKTIME -# define DEBUG_MKTIME 0 -#endif - -#if !defined _LIBC && !DEBUG_MKTIME -# include <config.h> -#endif - -/* Assume that leap seconds are possible, unless told otherwise. - If the host has a 'zic' command with a '-L leapsecondfilename' option, - then it supports leap seconds; otherwise it probably doesn't. */ -#ifndef LEAP_SECONDS_POSSIBLE -# define LEAP_SECONDS_POSSIBLE 1 -#endif - -#include <time.h> - -#include <limits.h> -#include <stdbool.h> - -#include <intprops.h> -#include <verify.h> - -#if DEBUG_MKTIME -# include <stdio.h> -# include <stdlib.h> -# include <string.h> -/* Make it work even if the system's libc has its own mktime routine. */ -# undef mktime -# define mktime my_mktime -#endif - -/* A signed type that can represent an integer number of years - multiplied by three times the number of seconds in a year. It is - needed when converting a tm_year value times the number of seconds - in a year. The factor of three comes because these products need - to be subtracted from each other, and sometimes with an offset - added to them, without worrying about overflow. - - Much of the code uses long_int to represent time_t values, to - lessen the hassle of dealing with platforms where time_t is - unsigned, and because long_int should suffice to represent all - time_t values that mktime can generate even on platforms where - time_t is excessively wide. */ - -#if INT_MAX <= LONG_MAX / 3 / 366 / 24 / 60 / 60 -typedef long int long_int; -#else -typedef long long int long_int; -#endif -verify (INT_MAX <= TYPE_MAXIMUM (long_int) / 3 / 366 / 24 / 60 / 60); - -/* Shift A right by B bits portably, by dividing A by 2**B and - truncating towards minus infinity. B should be in the range 0 <= B - <= LONG_INT_BITS - 2, where LONG_INT_BITS is the number of useful - bits in a long_int. LONG_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. */ - -static long_int -shr (long_int a, int b) -{ - long_int one = 1; - return (-one >> 1 == -1 - ? a >> b - : a / (one << b) - (a % (one << b) < 0)); -} - -/* Bounds for the intersection of time_t and long_int. */ - -static long_int const mktime_min - = ((TYPE_SIGNED (time_t) && TYPE_MINIMUM (time_t) < TYPE_MINIMUM (long_int)) - ? TYPE_MINIMUM (long_int) : TYPE_MINIMUM (time_t)); -static long_int const mktime_max - = (TYPE_MAXIMUM (long_int) < TYPE_MAXIMUM (time_t) - ? TYPE_MAXIMUM (long_int) : TYPE_MAXIMUM (time_t)); - -verify (TYPE_IS_INTEGER (time_t)); - -#define EPOCH_YEAR 1970 -#define TM_YEAR_BASE 1900 -verify (TM_YEAR_BASE % 100 == 0); - -/* Is YEAR + TM_YEAR_BASE a leap year? */ -static bool -leapyear (long_int year) -{ - /* Don't add YEAR to TM_YEAR_BASE, as that might overflow. - Also, work even if YEAR is negative. */ - return - ((year & 3) == 0 - && (year % 100 != 0 - || ((year / 100) & 3) == (- (TM_YEAR_BASE / 100) & 3))); -} - -/* How many days come before each month (0-12). */ -#ifndef _LIBC -static -#endif -const unsigned short int __mon_yday[2][13] = - { - /* Normal years. */ - { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 }, - /* Leap years. */ - { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 } - }; - - -#ifdef _LIBC -typedef time_t mktime_offset_t; -#else -/* 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 - -/* Do 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 bool -isdst_differ (int a, int b) -{ - return (!a != !b) && (0 <= a) && (0 <= b); -} - -/* 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 overflow - when multiplied by three times the number of seconds in a year, and - likewise for YDAY1 and three times the number of seconds in a day. */ - -static long_int -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 (-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 without overflowing. */ - long_int years = year1 - year0; - long_int days = 365 * years + yday1 - yday0 + intervening_leap_days; - long_int hours = 24 * days + hour1 - hour0; - long_int minutes = 60 * hours + min1 - min0; - long_int seconds = 60 * minutes + sec1 - sec0; - return seconds; -} - -/* Return the average of A and B, even if A + B would overflow. - Round toward positive infinity. */ -static long_int -long_int_avg (long_int a, long_int b) -{ - return shr (a, 1) + shr (b, 1) + ((a | b) & 1); -} - -/* 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. - Although T and the returned value are of type long_int, - they represent time_t values and must be in time_t range. - If TP is null, return a value not equal to T; this avoids false matches. - YEAR and YDAY must not be so large that multiplying them by three times the - number of seconds in a year (or day, respectively) would overflow long_int. - If the returned value would be out of range, yield the minimal or - maximal in-range value, except do not yield a value equal to T. */ -static long_int -guess_time_tm (long_int year, long_int yday, int hour, int min, int sec, - long_int t, const struct tm *tp) -{ - if (tp) - { - long_int result; - long_int d = ydhms_diff (year, yday, hour, min, sec, - tp->tm_year, tp->tm_yday, - tp->tm_hour, tp->tm_min, tp->tm_sec); - if (! INT_ADD_WRAPV (t, d, &result)) - return result; - } - - /* 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 < long_int_avg (mktime_min, mktime_max) - ? (t <= mktime_min + 1 ? t + 1 : mktime_min) - : (mktime_max - 1 <= t ? t - 1 : mktime_max)); -} - -/* Use CONVERT to convert T to a struct tm value in *TM. T must be in - range for time_t. Return TM if successful, NULL if T is out of - range for CONVERT. */ -static struct tm * -convert_time (struct tm *(*convert) (const time_t *, struct tm *), - long_int t, struct tm *tm) -{ - time_t x = t; - return convert (&x, tm); -} - -/* 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. - A value is in range if it fits in both time_t and long_int. */ -static struct tm * -ranged_convert (struct tm *(*convert) (const time_t *, struct tm *), - long_int *t, struct tm *tp) -{ - struct tm *r; - if (*t < mktime_min) - *t = mktime_min; - else if (mktime_max < *t) - *t = mktime_max; - r = convert_time (convert, *t, tp); - - if (!r && *t) - { - long_int bad = *t; - long_int ok = 0; - - /* BAD is a known unconvertible value, and OK is a known good one. - Use binary search to narrow the range between BAD and OK until - they differ by 1. */ - while (true) - { - long_int mid = long_int_avg (ok, bad); - if (mid != ok && mid != bad) - break; - r = convert_time (convert, mid, tp); - if (r) - ok = mid; - else - bad = mid; - } - - if (!r && ok) - { - /* The last conversion attempt failed; - revert to the most recent successful attempt. */ - r = convert_time (convert, ok, tp); - } - } - - return r; -} - -/* Convert *TP to a time_t value, inverting - the monotonic and mostly-unit-linear conversion function CONVERT. - Use *OFFSET to keep track of a guess at the offset of the result, - compared to what the result would be for UTC without leap seconds. - If *OFFSET's guess is correct, only one CONVERT call is needed. - This function is external because it is used also by timegm.c. */ -time_t -__mktime_internal (struct tm *tp, - struct tm *(*convert) (const time_t *, struct tm *), - mktime_offset_t *offset) -{ - long_int t, gt, t0, t1, t2, dt; - 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 overflows correctly. */ - - /* 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; - - int negative_offset_guess; - - int sec_requested = sec; - - if (LEAP_SECONDS_POSSIBLE) - { - /* Handle out-of-range seconds specially, - since ydhms_tm_diff assumes every minute has 60 seconds. */ - if (sec < 0) - sec = 0; - if (59 < sec) - sec = 59; - } - - /* Invert CONVERT by probing. First assume the same offset as last - time. */ - - INT_SUBTRACT_WRAPV (0, *offset, &negative_offset_guess); - t0 = ydhms_diff (year, yday, hour, min, sec, - EPOCH_YEAR - TM_YEAR_BASE, 0, 0, 0, negative_offset_guess); - - /* 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) - { - long_int ot; - if (! INT_ADD_WRAPV (t, delta * direction, &ot)) - { - 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; - } - } - } - } - - offset_found: - /* Set *OFFSET to the low-order bits of T - T0 - NEGATIVE_OFFSET_GUESS. - This is just a heuristic to speed up the next mktime call, and - correctness is unaffected if integer overflow occurs here. */ - INT_SUBTRACT_WRAPV (t, t0, &dt); - INT_SUBTRACT_WRAPV (dt, negative_offset_guess, offset); - - 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. */ - long_int sec_adjustment = sec == 0 && tm.tm_sec == 60; - sec_adjustment -= sec; - sec_adjustment += sec_requested; - if (INT_ADD_WRAPV (t, sec_adjustment, &t) - || ! (mktime_min <= t && t <= mktime_max) - || ! convert_time (convert, t, &tm)) - return -1; - } - - *tp = tm; - return t; -} - - -static mktime_offset_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 (); -#elif HAVE_TZSET - 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_MKTIME - -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)); -} - -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; - - /* Sanity check, plus call tzset. */ - tl = 0; - if (! localtime (&tl)) - { - printf ("localtime (0) fails\n"); - status = 1; - } - - 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_r (&tl, &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_r (&tl, &tml); - if (lt) - { - tmk = tml; - tk = mktime (&tmk); - status |= check_result (tk, tmk, tl, &tml); - } - else - { - printf ("localtime_r (%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_r (&tl, &tml); - if (lt) - { - tmk = tml; - tk = tl; - status |= check_result (tk, tmk, tl, &tml); - } - else - { - printf ("localtime_r (%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_MKTIME */ - -/* -Local Variables: -compile-command: "gcc -DDEBUG_MKTIME -I. -Wall -W -O2 -g mktime.c -o mktime" -End: -*/ |