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/* free mktime function
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Copyright 1988, 1989 by David MacKenzie <djm@ai.mit.edu>
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and Michael Haertel <mike@ai.mit.edu>
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Unlimited distribution permitted provided this copyright notice is
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retained and any functional modifications are prominently identified. */
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/* Revised 1997 by Christian Spieler:
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The code was changed to get more conformance with ANSI's (resp. modern
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UNIX releases) definition for mktime():
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- Added adjustment for out-of-range values in the fields of struct tm.
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- Added iterations to get the correct UTC result for input values at
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the gaps when daylight saving time is switched on or off.
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- Allow forcing of DST "on" or DST "off" by setting `tm_isdst' field in
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the tm struct to positive number resp. zero. The `tm_isdst' field must
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be negative on entrance of mktime() to enable automatic determination
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if DST is in effect for the requested local time.
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- Added optional check for overflowing the time_t range. */
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/* Note: This version of mktime is ignorant of the tzfile.
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When the tm structure passed to mktime represents a local time that
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is valid both as DST time and as standard time (= time value in the
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gap when switching from DST back to standard time), the behaviour
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for `tm_isdst < 0' depends on the current timezone: TZ east of GMT
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assumes winter time, TZ west of GMT assumes summer time.
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Although mktime() (resp. mkgmtime()) tries to adjust for invalid values
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of struct tm members, this may fail for input values that are far away
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from the valid ranges. The adjustment process does not check for overflows
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or wrap arounds in the struct tm components. */
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time_t mkgmtime OF((struct tm *));
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time_t mktime OF((struct tm *));
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/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
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of the local time and date in the exploded time structure `tm',
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adjust out of range fields in `tm' and set `tm->tm_yday', `tm->tm_wday'.
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If `tm->tm_isdst < 0' was passed to mktime(), the correct setting of
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tm_isdst is determined and returned. Otherwise, mktime() assumes this
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field as valid; its information is used when converting local time
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Return -1 if time in `tm' cannot be represented as time_t value. */
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struct tm *ltm; /* Local time. */
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time_t loctime; /* The time_t value of local time. */
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time_t then; /* The time to return. */
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long tzoffset_adj; /* timezone-adjustment `remainder' */
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int bailout_cnt; /* counter of tries for tz correction */
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int save_isdst; /* Copy of the tm->isdst input value */
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save_isdst = tm->tm_isdst;
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loctime = mkgmtime(tm);
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tm->tm_isdst = save_isdst;
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/* Correct for the timezone and any daylight savings time.
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The correction is verified and repeated when not correct, to
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take into account the rare case that a change to or from daylight
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savings time occurs between when it is the time in `tm' locally
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and when it is that time in Greenwich. After the second correction,
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the "timezone & daylight" offset should be correct in all cases. To
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be sure, we allow a third try, but then the loop is stopped. */
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ltm = localtime(&then);
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if (ltm == (struct tm *)NULL ||
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(tzoffset_adj = loctime - mkgmtime(ltm)) == 0L)
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} while (--bailout_cnt > 0);
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if (ltm == (struct tm *)NULL || tzoffset_adj != 0L) {
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/* Signal failure if timezone adjustment did not converge. */
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tm->tm_isdst = save_isdst;
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if (save_isdst >= 0) {
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if (ltm->tm_isdst && !save_isdst)
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if (then + 3600 < then)
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else if (!ltm->tm_isdst && save_isdst)
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if (then - 3600 > then)
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ltm->tm_isdst = save_isdst;
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if (tm != ltm) /* `tm' may already point to localtime's internal storage */
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#ifndef NO_TIME_T_MAX
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/* Provide default values for the upper limit of the time_t range.
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These are the result of the decomposition into a `struct tm' for
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the time value 0xFFFFFFFEL ( = (time_t)-2 ).
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Note: `(time_t)-1' is reserved for "invalid time"! */
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# define TM_YEAR_MAX 2106
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# define TM_MON_MAX 1 /* February */
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# define TM_MDAY_MAX 7
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# define TM_HOUR_MAX 6
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# define TM_MIN_MAX 28
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# define TM_SEC_MAX 14
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#endif /* NO_TIME_T_MAX */
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/* Adjusts out-of-range values for `tm' field `tm_member'. */
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#define ADJUST_TM(tm_member, tm_carry, modulus) \
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if ((tm_member) < 0) { \
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tm_carry -= (1 - ((tm_member)+1) / (modulus)); \
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tm_member = (modulus-1) + (((tm_member)+1) % (modulus)); \
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} else if ((tm_member) >= (modulus)) { \
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tm_carry += (tm_member) / (modulus); \
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tm_member = (tm_member) % (modulus); \
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/* Nonzero if `y' is a leap year, else zero. */
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#define leap(y) (((y) % 4 == 0 && (y) % 100 != 0) || (y) % 400 == 0)
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/* Number of leap years from 1970 to `y' (not including `y' itself). */
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#define nleap(y) (((y) - 1969) / 4 - ((y) - 1901) / 100 + ((y) - 1601) / 400)
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/* Additional leapday in February of leap years. */
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#define leapday(m, y) ((m) == 1 && leap (y))
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/* Length of month `m' (0 .. 11) */
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#define monthlen(m, y) (ydays[(m)+1] - ydays[m] + leapday (m, y))
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/* Accumulated number of days from 01-Jan up to start of current month. */
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static ZCONST short ydays[] =
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0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
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/* Return the equivalent in seconds past 12:00:00 a.m. Jan 1, 1970 GMT
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of the Greenwich Mean time and date in the exploded time structure `tm'.
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This function does always put back normalized values into the `tm' struct,
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parameter, including the calculated numbers for `tm->tm_yday',
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`tm->tm_wday', and `tm->tm_isdst'.
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Returns -1 if the time in the `tm' parameter cannot be represented
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as valid `time_t' number. */
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int years, months, days, hours, minutes, seconds;
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years = tm->tm_year + 1900; /* year - 1900 -> year */
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months = tm->tm_mon; /* 0..11 */
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days = tm->tm_mday - 1; /* 1..31 -> 0..30 */
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hours = tm->tm_hour; /* 0..23 */
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minutes = tm->tm_min; /* 0..59 */
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seconds = tm->tm_sec; /* 0..61 in ANSI C. */
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ADJUST_TM(seconds, minutes, 60)
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ADJUST_TM(minutes, hours, 60)
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ADJUST_TM(hours, days, 24)
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ADJUST_TM(months, years, 12)
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days += monthlen(months, years);
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while (days >= monthlen(months, years)) {
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days -= monthlen(months, years);
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if (++months >= 12) {
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/* Restore adjusted values in tm structure */
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tm->tm_year = years - 1900;
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tm->tm_mday = days + 1;
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tm->tm_min = minutes;
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tm->tm_sec = seconds;
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/* Set `days' to the number of days into the year. */
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days += ydays[months] + (months > 1 && leap (years));
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/* Now calculate `days' to the number of days since Jan 1, 1970. */
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days = (unsigned)days + 365 * (unsigned)(years - 1970) +
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(unsigned)(nleap (years));
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tm->tm_wday = ((unsigned)days + 4) % 7; /* Jan 1, 1970 was Thursday. */
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#if (defined(TM_YEAR_MAX) && defined(TM_MON_MAX) && defined(TM_MDAY_MAX))
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#if (defined(TM_HOUR_MAX) && defined(TM_MIN_MAX) && defined(TM_SEC_MAX))
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if (years > TM_YEAR_MAX ||
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(years == TM_YEAR_MAX &&
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(tm->tm_yday > ydays[TM_MON_MAX] + (TM_MDAY_MAX - 1) +
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(TM_MON_MAX > 1 && leap (TM_YEAR_MAX)) ||
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(tm->tm_yday == ydays[TM_MON_MAX] + (TM_MDAY_MAX - 1) +
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(TM_MON_MAX > 1 && leap (TM_YEAR_MAX)) &&
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(hours > TM_HOUR_MAX ||
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(hours == TM_HOUR_MAX &&
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(minutes > TM_MIN_MAX ||
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(minutes == TM_MIN_MAX && seconds > TM_SEC_MAX) )))))))
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return (time_t)(86400L * (unsigned long)(unsigned)days +
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3600L * (unsigned long)hours +
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(unsigned long)(60 * minutes + seconds));
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const char *BOINC_RCSID_945276575a = "$Id: mktime.c 4979 2005-01-02 18:29:53Z ballen $";
added
removed
zip/zip/mktime.c
