diff options
Diffstat (limited to 'util-linux/hwclock.c')
| -rw-r--r-- | util-linux/hwclock.c | 44 |
1 files changed, 32 insertions, 12 deletions
diff --git a/util-linux/hwclock.c b/util-linux/hwclock.c index 08e5bd701..606721e2c 100644 --- a/util-linux/hwclock.c +++ b/util-linux/hwclock.c @@ -20,34 +20,54 @@ static const char *rtcname; -static time_t read_rtc(int utc) +static time_t read_rtc(struct timeval *sys_tv, int utc) { - time_t ret; + struct tm tm; int fd; + int before; fd = rtc_xopen(&rtcname, O_RDONLY); - ret = rtc_read_time(fd, utc); + + rtc_read_tm(&tm, fd); + before = tm.tm_sec; + while (1) { + rtc_read_tm(&tm, fd); + gettimeofday(sys_tv, NULL); + if (before != tm.tm_sec) + break; + } + if (ENABLE_FEATURE_CLEAN_UP) close(fd); - return ret; + return rtc_tm2time(&tm, utc); } static void show_clock(int utc) { - //struct tm *ptm; + struct timeval sys_tv; time_t t; + long diff; char *cp; - t = read_rtc(utc); - //ptm = localtime(&t); /* Sets 'tzname[]' */ + t = read_rtc(&sys_tv, utc); cp = ctime(&t); strchrnul(cp, '\n')[0] = '\0'; //printf("%s 0.000000 seconds %s\n", cp, utc ? "" : (ptm->tm_isdst ? tzname[1] : tzname[0])); - /* 0.000000 stand for unimplemented difference between RTC and system clock */ - printf("%s 0.000000 seconds\n", cp); + diff = sys_tv.tv_sec - t; + if (diff < 0 /*&& tv.tv_usec != 0*/) { + /* Why? */ + /* diff >= 0 is ok: diff < 0, can't just use tv.tv_usec: */ + /* 45.520820 43.520820 */ + /* - 44.000000 - 45.000000 */ + /* = 0.520820 = -1.479180, not -2.520820! */ + diff++; + /* should be 1000000 - tv.tv_usec, but then we must check tv.tv_usec != 0 */ + sys_tv.tv_usec = 999999 - sys_tv.tv_usec; + } + printf("%s %ld.%06lu seconds\n", cp, diff, (unsigned long)sys_tv.tv_usec); } static void to_sys_clock(int utc) @@ -58,7 +78,7 @@ static void to_sys_clock(int utc) tz.tz_minuteswest = timezone/60 - 60*daylight; tz.tz_dsttime = 0; - tv.tv_sec = read_rtc(utc); + tv.tv_sec = read_rtc(NULL, utc); tv.tv_usec = 0; if (settimeofday(&tv, &tz)) bb_perror_msg_and_die("settimeofday() failed"); @@ -79,15 +99,15 @@ static void from_sys_clock(int utc) gettimeofday(&tv, NULL); + t = tv.tv_sec; rem_usec = 1000000 - tv.tv_usec; if (rem_usec < 1024) { /* Less than 1ms to next second. Good enough */ small_rem: - tv.tv_sec++; + t++; } /* Prepare tm */ - t = tv.tv_sec; if (utc) gmtime_r(&t, &tm); /* may read /etc/xxx (it takes time) */ else |