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/* vi: set sw=4 ts=4: */
/*
* Mini hwclock implementation for busybox
*
* Copyright (C) 2002 Robert Griebl <griebl@gmx.de>
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include "libbb.h"
/* After libbb.h, since it needs sys/types.h on some systems */
#include <sys/utsname.h>
#include "rtc_.h"
#if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
# ifndef _GNU_SOURCE
# define _GNU_SOURCE
# endif
#endif
/* diff code is disabled: it's not sys/hw clock diff, it's some useless
* "time between hwclock was started and we saw CMOS tick" quantity.
* It's useless since hwclock is started at a random moment,
* thus the quantity is also random, useless. Showing 0.000000 does not
* deprive us from any useful info.
*
* SHOW_HWCLOCK_DIFF code in this file shows the difference between system
* and hw clock. It is useful, but not compatible with standard hwclock.
* Thus disabled.
*/
#define SHOW_HWCLOCK_DIFF 0
#if !SHOW_HWCLOCK_DIFF
# define read_rtc(pp_rtcname, sys_tv, utc) read_rtc(pp_rtcname, utc)
#endif
static time_t read_rtc(const char **pp_rtcname, struct timeval *sys_tv, int utc)
{
struct tm tm;
int fd;
fd = rtc_xopen(pp_rtcname, O_RDONLY);
rtc_read_tm(&tm, fd);
#if SHOW_HWCLOCK_DIFF
{
int before = tm.tm_sec;
while (1) {
rtc_read_tm(&tm, fd);
gettimeofday(sys_tv, NULL);
if (before != tm.tm_sec)
break;
}
}
#endif
if (ENABLE_FEATURE_CLEAN_UP)
close(fd);
return rtc_tm2time(&tm, utc);
}
static void show_clock(const char **pp_rtcname, int utc)
{
#if SHOW_HWCLOCK_DIFF
struct timeval sys_tv;
#endif
time_t t;
char *cp;
t = read_rtc(pp_rtcname, &sys_tv, utc);
cp = ctime(&t);
strchrnul(cp, '\n')[0] = '\0';
#if !SHOW_HWCLOCK_DIFF
printf("%s 0.000000 seconds\n", cp);
#else
{
long 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 */
/* = 1.520820 = -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);
}
#endif
}
static void to_sys_clock(const char **pp_rtcname, int utc)
{
struct timeval tv;
struct timezone tz;
tz.tz_minuteswest = timezone/60 - 60*daylight;
tz.tz_dsttime = 0;
tv.tv_sec = read_rtc(pp_rtcname, NULL, utc);
tv.tv_usec = 0;
if (settimeofday(&tv, &tz))
bb_perror_msg_and_die("settimeofday");
}
static void from_sys_clock(const char **pp_rtcname, int utc)
{
#define TWEAK_USEC 200
struct tm tm;
struct timeval tv;
unsigned adj = TWEAK_USEC;
int rtc = rtc_xopen(pp_rtcname, O_WRONLY);
/* Try to catch the moment when whole second is close */
while (1) {
unsigned rem_usec;
time_t t;
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:
t++;
}
/* Prepare tm */
if (utc)
gmtime_r(&t, &tm); /* may read /etc/xxx (it takes time) */
else
localtime_r(&t, &tm); /* same */
tm.tm_isdst = 0;
/* gmtime/localtime took some time, re-get cur time */
gettimeofday(&tv, NULL);
if (tv.tv_sec < t /* may happen if rem_usec was < 1024 */
|| (tv.tv_sec == t && tv.tv_usec < 1024)
) {
/* We are not too far into next second. Good. */
break;
}
adj += 32; /* 2^(10-5) = 2^5 = 32 iterations max */
if (adj >= 1024) {
/* Give up trying to sync */
break;
}
/* Try to sync up by sleeping */
rem_usec = 1000000 - tv.tv_usec;
if (rem_usec < 1024) {
goto small_rem; /* already close, don't sleep */
}
/* Need to sleep.
* Note that small adj on slow processors can make us
* to always overshoot tv.tv_usec < 1024 check on next
* iteration. That's why adj is increased on each iteration.
* This also allows it to be reused as a loop limiter.
*/
usleep(rem_usec - adj);
}
xioctl(rtc, RTC_SET_TIME, &tm);
/* Debug aid to find "good" TWEAK_USEC.
* Look for a value which makes tv_usec close to 999999 or 0.
* for 2.20GHz Intel Core 2: TWEAK_USEC ~= 200
*/
//bb_error_msg("tv.tv_usec:%d adj:%d", (int)tv.tv_usec, adj);
if (ENABLE_FEATURE_CLEAN_UP)
close(rtc);
}
#define HWCLOCK_OPT_LOCALTIME 0x01
#define HWCLOCK_OPT_UTC 0x02
#define HWCLOCK_OPT_SHOW 0x04
#define HWCLOCK_OPT_HCTOSYS 0x08
#define HWCLOCK_OPT_SYSTOHC 0x10
#define HWCLOCK_OPT_RTCFILE 0x20
int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int hwclock_main(int argc UNUSED_PARAM, char **argv)
{
const char *rtcname = NULL;
unsigned opt;
int utc;
#if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
static const char hwclock_longopts[] ALIGN1 =
"localtime\0" No_argument "l"
"utc\0" No_argument "u"
"show\0" No_argument "r"
"hctosys\0" No_argument "s"
"systohc\0" No_argument "w"
"file\0" Required_argument "f"
;
applet_long_options = hwclock_longopts;
#endif
opt_complementary = "r--ws:w--rs:s--wr:l--u:u--l";
opt = getopt32(argv, "lurswf:", &rtcname);
/* If -u or -l wasn't given check if we are using utc */
if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME))
utc = (opt & HWCLOCK_OPT_UTC);
else
utc = rtc_adjtime_is_utc();
if (opt & HWCLOCK_OPT_HCTOSYS)
to_sys_clock(&rtcname, utc);
else if (opt & HWCLOCK_OPT_SYSTOHC)
from_sys_clock(&rtcname, utc);
else
/* default HWCLOCK_OPT_SHOW */
show_clock(&rtcname, utc);
return 0;
}
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