hwclock: make it report system/rtc clock difference

function                                             old     new   delta
rtc_tm2time                                            -      89     +89
read_rtc                                              23      86     +63
rtc_read_tm                                            -      49     +49
hwclock_main                                         428     466     +38
rtcwake_main                                         453     477     +24
rtc_read_time                                        142       -    -142
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 3/0 up/down: 263/-142)          Total: 121 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/include/rtc_.h b/include/rtc_.h
index 74bb695..2b4ae77 100644 (file)
--- a/include/rtc_.h
+++ b/include/rtc_.h
@@ -11,9 +11,11 @@
 
 PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
 
-extern int rtc_adjtime_is_utc(void) FAST_FUNC;
-extern int rtc_xopen(const char **default_rtc, int flags) FAST_FUNC;
-extern time_t rtc_read_time(int fd, int utc) FAST_FUNC;
+int rtc_adjtime_is_utc(void) FAST_FUNC;
+int rtc_xopen(const char **default_rtc, int flags) FAST_FUNC;
+void rtc_read_tm(struct tm *tm, int fd) FAST_FUNC;
+time_t rtc_tm2time(struct tm *tm, int utc) FAST_FUNC;
+
 
 /*
  * Everything below this point has been copied from linux/rtc.h

diff --git a/libbb/rtc.c b/libbb/rtc.c
index 2f38b8a..9807e1c 100644 (file)
--- a/libbb/rtc.c
+++ b/libbb/rtc.c
@@ -59,15 +59,17 @@ int FAST_FUNC rtc_xopen(const char **default_rtc, int flags)
        return xopen(*default_rtc, flags);
 }
 
-time_t FAST_FUNC rtc_read_time(int fd, int utc)
+void FAST_FUNC rtc_read_tm(struct tm *tm, int fd)
 {
-       struct tm tm;
-       char *oldtz = 0;
-       time_t t = 0;
+       memset(tm, 0, sizeof(*tm));
+       xioctl(fd, RTC_RD_TIME, tm);
+       tm->tm_isdst = -1; /* "not known" */
+}
 
-       memset(&tm, 0, sizeof(struct tm));
-       xioctl(fd, RTC_RD_TIME, &tm);
-       tm.tm_isdst = -1; /* not known */
+time_t FAST_FUNC rtc_tm2time(struct tm *tm, int utc)
+{
+       char *oldtz = oldtz; /* for compiler */
+       time_t t;
 
        if (utc) {
                oldtz = getenv("TZ");
@@ -75,7 +77,7 @@ time_t FAST_FUNC rtc_read_time(int fd, int utc)
                tzset();
        }
 
-       t = mktime(&tm);
+       t = mktime(tm);
 
        if (utc) {
                unsetenv("TZ");

diff --git a/util-linux/hwclock.c b/util-linux/hwclock.c
index 08e5bd7..606721e 100644 (file)
--- 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

diff --git a/util-linux/rtcwake.c b/util-linux/rtcwake.c
index 049f699..64c3e7e 100644 (file)
--- a/util-linux/rtcwake.c
+++ b/util-linux/rtcwake.c
@@ -160,7 +160,12 @@ int rtcwake_main(int argc UNUSED_PARAM, char **argv)
 
        /* relative or absolute alarm time, normalized to time_t */
        sys_time = time(NULL);
-       rtc_time = rtc_read_time(fd, utc);
+       {
+               struct tm tm;
+               rtc_read_tm(&tm, fd);
+               rtc_time = rtc_tm2time(&tm, utc);
+       }
+
 
        if (alarm_time) {
                if (alarm_time < sys_time)