prtime.c

Netscape NSPR库源码

            }
            time->tm_mday = nDays[IsLeapYear(time->tm_year)][time->tm_month];
        }
        time->tm_wday--;
        if (time->tm_wday < 0)
            time->tm_wday = 6;
    } else if (time->tm_hour > 23) {
        /* Increment mday, yday, and wday */
        time->tm_hour -= 24;
        time->tm_mday++;
        time->tm_yday++;
        if (time->tm_mday >
                nDays[IsLeapYear(time->tm_year)][time->tm_month]) {
            time->tm_mday = 1;
            time->tm_month++;
            if (time->tm_month > 11) {
                time->tm_month = 0;
                time->tm_year++;
                time->tm_yday = 0;
            }
        }
        time->tm_wday++;
        if (time->tm_wday > 6)
            time->tm_wday = 0;
    }
}

PR_IMPLEMENT(void)
PR_NormalizeTime(PRExplodedTime *time, PRTimeParamFn params)
{
    int daysInMonth;
    PRInt32 fourYears;
    PRInt32 remainder;
    PRInt32 numDays;

    /* Get back to GMT */
    time->tm_sec -= time->tm_params.tp_gmt_offset
            + time->tm_params.tp_dst_offset;
    time->tm_params.tp_gmt_offset = 0;
    time->tm_params.tp_dst_offset = 0;

    /* Now normalize GMT */

    if (time->tm_usec < 0 || time->tm_usec >= 1000000) {
        time->tm_sec +=  time->tm_usec / 1000000;
        time->tm_usec %= 1000000;
        if (time->tm_usec < 0) {
            time->tm_usec += 1000000;
            time->tm_sec--;
        }
    }

    /* Note that we do not count leap seconds in this implementation */
    if (time->tm_sec < 0 || time->tm_sec >= 60) {
        time->tm_min += time->tm_sec / 60;
        time->tm_sec %= 60;
        if (time->tm_sec < 0) {
            time->tm_sec += 60;
            time->tm_min--;
        }
    }

    if (time->tm_min < 0 || time->tm_min >= 60) {
        time->tm_hour += time->tm_min / 60;
        time->tm_min %= 60;
        if (time->tm_min < 0) {
            time->tm_min += 60;
            time->tm_hour--;
        }
    }

    if (time->tm_hour < 0 || time->tm_hour >= 24) {
        time->tm_mday += time->tm_hour / 24;
        time->tm_hour %= 24;
        if (time->tm_hour < 0) {
            time->tm_hour += 24;
            time->tm_mday--;
        }
    }

    /* Normalize month and year before mday */
    if (time->tm_month < 0 || time->tm_month >= 12) {
        time->tm_year += time->tm_month / 12;
        time->tm_month %= 12;
        if (time->tm_month < 0) {
            time->tm_month += 12;
            time->tm_year--;
        }
    }

    /* Now that month and year are in proper range, normalize mday */

    if (time->tm_mday < 1) {
        /* mday too small */
        do {
            /* the previous month */
            time->tm_month--;
            if (time->tm_month < 0) {
                time->tm_month = 11;
                time->tm_year--;
            }
            time->tm_mday += nDays[IsLeapYear(time->tm_year)][time->tm_month];
        } while (time->tm_mday < 1);
    } else {
        daysInMonth = nDays[IsLeapYear(time->tm_year)][time->tm_month];
        while (time->tm_mday > daysInMonth) {
            /* mday too large */
            time->tm_mday -= daysInMonth;
            time->tm_month++;
            if (time->tm_month > 11) {
                time->tm_month = 0;
                time->tm_year++;
            }
            daysInMonth = nDays[IsLeapYear(time->tm_year)][time->tm_month];
        }
    }

    /* Recompute yday and wday */
    time->tm_yday = time->tm_mday +
            lastDayOfMonth[IsLeapYear(time->tm_year)][time->tm_month];
    fourYears = (time->tm_year - 1970) / 4;
    remainder = (time->tm_year - 1970) % 4;
    if (remainder < 0) {
        remainder += 4;
        fourYears--;
    }
    numDays = fourYears * (4 * 365 + 1);
    switch (remainder) {
        case 0:
            break;
        case 1:
            numDays += 365;  /* 1970 */
            break;
        case 2:
            numDays += 365 + 365;  /* 1970 and 1971 */
            break;
        case 3:
            numDays += 365 + 365 + 366; /* 1970-2 */
    }
    numDays += time->tm_yday;
    time->tm_wday = (numDays + 4) % 7;
    if (time->tm_wday < 0) {
        time->tm_wday += 7;
    }

    /* Recompute time parameters */

    time->tm_params = params(time);

    ApplySecOffset(time, time->tm_params.tp_gmt_offset
            + time->tm_params.tp_dst_offset);
}


/*
 *-------------------------------------------------------------------------
 *
 * PR_LocalTimeParameters --
 * 
 *     returns the time parameters for the local time zone
 *
 *     The following uses localtime() from the standard C library.
 *     (time.h)  This is our fallback implementation.  Unix and PC
 *     use this version.  Mac has its own machine-dependent
 *     implementation of this function.
 *
 *-------------------------------------------------------------------------
 */

#include <time.h>

#if defined(HAVE_INT_LOCALTIME_R)

/*
 * In this case we could define the macro as
 *     #define MT_safe_localtime(timer, result) \
 *             (localtime_r(timer, result) == 0 ? result : NULL)
 * I chose to compare the return value of localtime_r with -1 so 
 * that I can catch the cases where localtime_r returns a pointer
 * to struct tm.  The macro definition above would not be able to
 * detect such mistakes because it is legal to compare a pointer
 * with 0.
 */

#define MT_safe_localtime(timer, result) \
        (localtime_r(timer, result) == -1 ? NULL: result)

#elif defined(HAVE_POINTER_LOCALTIME_R)

#define MT_safe_localtime localtime_r

#else

#if defined(XP_MAC)
extern struct tm *Maclocaltime(const time_t * t);
#endif

static PRLock *monitor = NULL;

static struct tm *MT_safe_localtime(const time_t *clock, struct tm *result)
{
    struct tm *tmPtr;
    int needLock = PR_Initialized();  /* We need to use a lock to protect
                                       * against NSPR threads only when the
                                       * NSPR thread system is activated. */

    if (needLock) {
        if (monitor == NULL) {
            monitor = PR_NewLock();
        }
        PR_Lock(monitor);
    }

    /*
     * Microsoft (all flavors) localtime() returns a NULL pointer if 'clock'
     * represents a time before midnight January 1, 1970.  In
     * that case, we also return a NULL pointer and the struct tm
     * object pointed to by 'result' is not modified.
     *
     * Watcom C/C++ 11.0 localtime() treats time_t as unsigned long
     * hence, does not recognize negative values of clock as pre-1/1/70.
     * We have to manually check (WIN16 only) for negative value of
     * clock and return NULL.
     *
     * With negative values of clock, emx returns the struct tm for
     * clock plus ULONG_MAX. So we also have to check for the invalid
     * structs returned for timezones west of Greenwich when clock == 0.
     */
    
#if defined(XP_MAC)
    tmPtr = Maclocaltime(clock);
#else
    tmPtr = localtime(clock);
#endif

#if defined(WIN16) || defined(XP_OS2_EMX)
    if ( (PRInt32) *clock < 0 ||
         ( (PRInt32) *clock == 0 && tmPtr->tm_year != 70))
        result = NULL;
    else
        *result = *tmPtr;
#else
    if (tmPtr) {
        *result = *tmPtr;
    } else {
        result = NULL;
    }
#endif /* WIN16 */

    if (needLock) PR_Unlock(monitor);

    return result;
}

#endif  /* definition of MT_safe_localtime() */

#if defined(XP_UNIX) || defined(XP_PC) || defined(XP_BEOS)

PR_IMPLEMENT(PRTimeParameters)
PR_LocalTimeParameters(const PRExplodedTime *gmt)
{

    PRTimeParameters retVal;
    struct tm localTime;
    time_t secs;
    PRTime secs64;
    PRInt64 usecPerSec;
    PRInt64 maxInt32;
    PRInt32 dayOffset;
    PRInt32 offset2Jan1970;
    PRInt32 offsetNew;
    int isdst2Jan1970;

    /*
     * Calculate the GMT offset.  First, figure out what is
     * 00:00:00 Jan. 2, 1970 GMT (which is exactly a day, or 86400
     * seconds, since the epoch) in local time.  Then we calculate
     * the difference between local time and GMT in seconds:
     *     gmt_offset = local_time - GMT
     *
     * Caveat: the validity of this calculation depends on two
     * assumptions:
     * 1. Daylight saving time was not in effect on Jan. 2, 1970.
     * 2. The time zone of the geographic location has not changed
     *    since Jan. 2, 1970.
     */

    secs = 86400L;
    (void) MT_safe_localtime(&secs, &localTime);

    /* GMT is 00:00:00, 2nd of Jan. */

    offset2Jan1970 = (PRInt32)localTime.tm_sec 
            + 60L * (PRInt32)localTime.tm_min
            + 3600L * (PRInt32)localTime.tm_hour
            + 86400L * (PRInt32)((PRInt32)localTime.tm_mday - 2L);

    isdst2Jan1970 = localTime.tm_isdst;

    /*
     * Now compute DST offset.  We calculate the overall offset
     * of local time from GMT, similar to above.  The overall
     * offset has two components: gmt offset and dst offset.
     * We subtract gmt offset from the overall offset to get
     * the dst offset.
     *     overall_offset = local_time - GMT
     *     overall_offset = gmt_offset + dst_offset
     * ==> dst_offset = local_time - GMT - gmt_offset
     */

    secs64 = PR_ImplodeTime(gmt);    /* This is still in microseconds */
    LL_I2L(usecPerSec, PR_USEC_PER_SEC);
    LL_DIV(secs64, secs64, usecPerSec);   /* Convert to seconds */
    LL_I2L(maxInt32, 0x7fffffff);
    if (LL_CMP(secs64, >, maxInt32)) {
        /* secs64 is too large for time_t (32-bit integer) */
        retVal.tp_gmt_offset = offset2Jan1970;
        retVal.tp_dst_offset = 0;
        return retVal;
    }
    LL_L2I(secs, secs64);

    /*
     * On Windows, localtime() (and our MT_safe_localtime() too)
     * returns a NULL pointer for time before midnight January 1,
     * 1970 GMT.  In that case, we just use the GMT offset for
     * Jan 2, 1970 and assume that DST was not in effect.
     */

    if (MT_safe_localtime(&secs, &localTime) == NULL) {
        retVal.tp_gmt_offset = offset2Jan1970;
        retVal.tp_dst_offset = 0;
        return retVal;
    }

    /*
     * dayOffset is the offset between local time and GMT in 
     * the day component, which can only be -1, 0, or 1.  We
     * use the day of the week to compute dayOffset.
     */

    dayOffset = (PRInt32) localTime.tm_wday - gmt->tm_wday;

    /*
     * Need to adjust for wrapping around of day of the week from
     * 6 back to 0.
     */

    if (dayOffset == -6) {
        /* Local time is Sunday (0) and GMT is Saturday (6) */
        dayOffset = 1;
    } else if (dayOffset == 6) {
        /* Local time is Saturday (6) and GMT is Sunday (0) */
        dayOffset = -1;
    }

    offsetNew = (PRInt32)localTime.tm_sec - gmt->tm_sec
            + 60L * ((PRInt32)localTime.tm_min - gmt->tm_min)
            + 3600L * ((PRInt32)localTime.tm_hour - gmt->tm_hour)
            + 86400L * (PRInt32)dayOffset;

    if (localTime.tm_isdst <= 0) {
        /* DST is not in effect */
        retVal.tp_gmt_offset = offsetNew;
        retVal.tp_dst_offset = 0;
    } else {
        /* DST is in effect */
        if (isdst2Jan1970 <=0) {
            /*
             * DST was not in effect back in 2 Jan. 1970.
             * Use the offset back then as the GMT offset,