f0d81ffd1c
which included commits to RCS files with non-trunk default branches. git-svn-id: svn://10.65.10.50/trunk@5403 c028cbd2-c16b-5b4b-a496-9718f37d4682
110 lines
3.6 KiB
C
Executable File
110 lines
3.6 KiB
C
Executable File
/* 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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/* Note: This version of mktime is ignorant of the tzfile; it does not
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return correct results during the few hours around when daylight savings
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time goes in to or out of effect. It also does not allow or adjust
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for invalid values in any of the fields, contrary to the ANSI C
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specification. */
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#ifndef NO_SYS_TYPES_H
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# include <sys/types.h>
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#endif
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#include <time.h>
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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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and set `tm->tm_yday', `tm->tm_wday', and `tm->tm_isdst'.
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Return -1 if any of the other fields in `tm' has an invalid value. */
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time_t
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mktime (tm)
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struct tm *tm;
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{
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struct tm save_tm; /* Copy of contents of `*tm'. */
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struct tm *ltm; /* Local time. */
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time_t then; /* The time to return. */
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then = mkgmtime (tm);
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if (then == -1)
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return -1;
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/* In case `tm' points to the static area used by localtime,
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save its contents and restore them later. */
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save_tm = *tm;
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/* Correct for the timezone and any daylight savings time.
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If a change to or from daylight savings time occurs between when
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it is the time in `tm' locally and when it is that time in Greenwich,
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the change to or from dst is ignored, but that is a rare case. */
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then += then - mkgmtime (localtime (&then));
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ltm = localtime (&then);
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save_tm.tm_yday = ltm->tm_yday;
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save_tm.tm_wday = ltm->tm_wday;
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save_tm.tm_isdst = ltm->tm_isdst;
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*tm = save_tm;
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return then;
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}
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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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/* Number of days in each month of the year. */
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static const char monlens[] =
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{
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31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
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};
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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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and set `tm->tm_yday', `tm->tm_wday', and `tm->tm_isdst'.
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Return -1 if any of the other fields in `tm' has an invalid value. */
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time_t
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mkgmtime (tm)
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struct tm *tm;
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{
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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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if (years < 1970
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|| months < 0 || months > 11
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|| days < 0
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|| days > monlens[months] + (months == 1 && leap (years)) - 1
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|| hours < 0 || hours > 23
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|| minutes < 0 || minutes > 59
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|| seconds < 0 || seconds > 61)
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return -1;
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/* Set `days' to the number of days into the year. */
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if (months > 1 && leap (years))
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++days;
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while (months-- > 0)
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days += monlens[months];
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tm->tm_yday = days;
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/* Now set `days' to the number of days since Jan 1, 1970. */
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days += 365 * (years - 1970) + nleap (years);
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tm->tm_wday = (days + 4) % 7; /* Jan 1, 1970 was Thursday. */
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tm->tm_isdst = 0;
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return (time_t)(86400L * (long)days + 3600L * (long)hours +
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(long)(60 * minutes + seconds));
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}
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