获取时间

#define SECS_PER_HOUR (60 * 60)
#define SECS_PER_DAY (SECS_PER_HOUR * 24)

struct tm
{
        int tm_sec;
        int tm_min;
        int tm_hour;
        int tm_mday;
        int tm_mon;
        long tm_year;
        int tm_wday;
        int tm_yday;
};

static const unsigned short __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}
};

static int __isleap(long year)
{
        return (year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0);
}
        
/* do a mathdiv for long type */
static long math_div(long a, long b)
{
        return a / b - (a % b < 0);
}
        
/* How many leap years between y1 and y2, y1 must less or equal to y2 */
static long leaps_between(long y1, long y2)
{
        long leaps1 = math_div(y1 - 1, 4) - math_div(y1 - 1, 100)
                + math_div(y1 - 1, 400);
        long leaps2 = math_div(y2 - 1, 4) - math_div(y2 - 1, 100)
                + math_div(y2 - 1, 400);
        return leaps2 - leaps1;
}


static void time_to_tm(time_t totalsecs, int offset, struct tm *result)
{
        long days, rem, y;
        const unsigned short *ip;

        days = totalsecs / SECS_PER_DAY;
        rem = totalsecs % SECS_PER_DAY;
        rem += offset;
        while (rem < 0) {
                rem += SECS_PER_DAY;
                --days;
        }
        while (rem >= SECS_PER_DAY) {
                rem -= SECS_PER_DAY;
                ++days;
        }

        result->tm_hour = rem / SECS_PER_HOUR;
        rem %= SECS_PER_HOUR;
        result->tm_min = rem / 60;
        result->tm_sec = rem % 60;

        /* January 1, 1970 was a Thursday. */
        result->tm_wday = (4 + days) % 7;
        if (result->tm_wday < 0)
                result->tm_wday += 7;

        y = 1970;

        while (days < 0 || days >= (__isleap(y) ? 366 : 365)) {
                /* Guess a corrected year, assuming 365 days per year. */
                long yg = y + math_div(days, 365);

                /* Adjust DAYS and Y to match the guessed year. */
                days -= (yg - y) * 365 + leaps_between(y, yg);
                y = yg;
        }

        result->tm_year = y - 1900;
                                                                                  
        result->tm_yday = days;

        ip = __mon_yday[__isleap(y)];
        for (y = 11; days < ip[y]; y--)
                continue;
        days -= ip[y];

        result->tm_mon = y;
        result->tm_mday = days + 1;
}

static void print_current_time(void)
{
    struct timeval tv;
    struct tm tm;
    
    memset(&tv, '\0', sizeof(tv));
    do_gettimeofday(&tv);

    memset(&tm, '\0', sizeof(tm));
    time_to_tm(tv.tv_sec, 0, &tm);
    printk(KERN_INFO "hour: %d, minute: %d, second: %d\n", tm.tm_hour + 8, tm.tm_min, tm.tm_sec);
}