diff options
Diffstat (limited to 'libc/misc/time/mktime.c')
| -rw-r--r-- | libc/misc/time/mktime.c | 327 |
1 files changed, 0 insertions, 327 deletions
diff --git a/libc/misc/time/mktime.c b/libc/misc/time/mktime.c deleted file mode 100644 index 065126e0e..000000000 --- a/libc/misc/time/mktime.c +++ /dev/null @@ -1,327 +0,0 @@ -/* Convert a `struct tm' to a time_t value. - Copyright (C) 1993, 94, 95, 96, 97, 98, 99 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. */ - -#include <features.h> -/* Assume that leap seconds are not possible */ -#undef LEAP_SECONDS_POSSIBLE -#include <sys/types.h> /* Some systems define `time_t' here. */ -#include <time.h> -#include <limits.h> - -#if 0 -#ifndef CHAR_BIT -# define CHAR_BIT 8 -#endif - -/* The extra casts work around common compiler bugs. */ -#define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) -/* The outer cast is needed to work around a bug in Cray C 5.0.3.0. - It is necessary at least when t == time_t. */ -#define TYPE_MINIMUM(t) ((t) (TYPE_SIGNED (t) \ - ? ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1) : (t) 0)) -#define TYPE_MAXIMUM(t) ((t) (~ (t) 0 - TYPE_MINIMUM (t))) - -#ifndef INT_MIN -# define INT_MIN TYPE_MINIMUM (int) -#endif -#ifndef INT_MAX -# define INT_MAX TYPE_MAXIMUM (int) -#endif - -#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 TM_YEAR_BASE 1900 -#define EPOCH_YEAR 1970 - - -/* How many days come before each month (0-12). */ -extern const unsigned short int __mon_yday[2][13]; - - - -/* 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 - { - /* 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; - - /* 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; -#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; - (dt = __ydhms_tm_diff (year, yday, hour, min, sec, - __ranged_convert (convert, &t, &tm))); - t1 = t2, t2 = t, t += dt) - if (t == t1 && t != t2 - && (isdst < 0 || 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. 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; - } - - *tp = tm; - return t; -} - - - -/* Convert *TP to a time_t value. */ -time_t mktime (struct tm *tp) -{ - static time_t localtime_offset; - /* 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 (); - - return __mktime_internal (tp, localtime_r, &localtime_offset); -} -#else - -/* Convert *TP to a time_t value. */ -time_t mktime (struct tm *tp) -{ - time_t m_secs=tp->tm_min*60; - time_t h_secs=tp->tm_hour*3600; - time_t d_secs=tp->tm_yday*86400; - time_t y_secs=(tp->tm_year-70)*31536000; - time_t l_secs1=((tp->tm_year-69)/4)*86400; - time_t l_secs2=((tp->tm_year-1)/100)*86400; - time_t l_secs3=((tp->tm_year+299)/400)*86400; - return m_secs+h_secs+d_secs+y_secs+l_secs1-l_secs2+l_secs3+tp->tm_gmtoff; -} -#endif |