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/* hwclock.c - get and set the hwclock
*
* Copyright 2014 Bilal Qureshi <bilal.jmi@gmail.com>
*
* No Standard.
*
USE_HWCLOCK(NEWTOY(hwclock, ">0(fast)f(rtc):u(utc)l(localtime)t(systz)w(systohc)s(hctosys)r(show)[!ul][!rsw]", TOYFLAG_USR|TOYFLAG_BIN))
config HWCLOCK
bool "hwclock"
default n
help
usage: hwclock [-rswtluf]
-f FILE Use specified device file instead of /dev/rtc (--show)
-l Hardware clock uses localtime (--localtime)
-r Show hardware clock time (--show)
-s Set system time from hardware clock (--hctosys)
-t Set the system time based on the current timezone (--systz)
-u Hardware clock uses UTC (--utc)
-w Set hardware clock from system time (--systohc)
*/
#define FOR_hwclock
#include "toys.h"
#include <linux/rtc.h>
GLOBALS(
char *fname;
int utc;
)
static int check_hctosys(struct dirtree* node)
{
FILE *fp;
if (!node->parent) return DIRTREE_RECURSE;
snprintf(toybuf, sizeof(toybuf), "/sys/class/rtc/%s/hctosys", node->name);
fp = fopen(toybuf, "r");
if (fp) {
int hctosys = 0;
int items = fscanf(fp, "%d", &hctosys);
fclose(fp);
if (items == 1 && hctosys == 1) {
snprintf(toybuf, sizeof(toybuf), "/dev/%s", node->name);
TT.fname = toybuf;
return DIRTREE_ABORT;
}
}
return 0;
}
// Search /sys/class/rtc for the RTC that the system clock is set from.
// See the kernel's Documentation/rtc.txt.
static int open_wall_clock_rtc(int flag)
{
TT.fname = NULL;
dirtree_read("/sys/class/rtc", check_hctosys);
return TT.fname ? xopen(TT.fname, flag) : -1;
}
static int rtc_open(int flag)
{
if (!TT.fname) {
int fd;
if ((fd = open((TT.fname = "/dev/rtc"), flag)) != -1) return fd;
else if ((fd = open_wall_clock_rtc(flag)) != -1) return fd;
else TT.fname = "/dev/misc/rtc";
}
return xopen(TT.fname, flag);
}
static time_t get_rtc()
{
struct tm time;
time_t tm;
char *ptz_old = 0;
int fd = rtc_open(O_RDONLY);
xioctl(fd, RTC_RD_TIME, &time);
close(fd);
if (TT.utc) {
ptz_old = getenv("TZ");
if (putenv((char*)"TZ=UTC0")) perror_exit("putenv");
tzset();
}
if ((tm = mktime(&time)) < 0) error_exit("mktime failed");
if (TT.utc) {
if (unsetenv("TZ") < 0) perror_exit("unsetenv");
if (ptz_old && putenv(ptz_old - 3)) perror_exit("putenv");
tzset();
}
return tm;
}
static void set_sysclock_from_hwclock()
{
struct timezone tmzone;
struct timeval tmval;
tmzone.tz_minuteswest = timezone / 60 - 60 * daylight;
tmzone.tz_dsttime = 0;
tmval.tv_sec = get_rtc();
tmval.tv_usec = 0;
if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday");
}
static void set_hwclock_from_sysclock()
{
struct timeval tmval;
struct tm time;
int fd = rtc_open(O_WRONLY);
if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
// converting a time value to broken-down UTC time
if (TT.utc && !gmtime_r((time_t*)&tmval.tv_sec, &time))
error_exit("gmtime_r failed");
// converting a time value to a broken-down localtime
else if (!(localtime_r((time_t*)&tmval.tv_sec, &time)))
error_exit("localtime_r failed");
/* The value of tm_isdst will positive if daylight saving time is in effect,
* zero if it is not and negative if the information is not available.
* */
time.tm_isdst = 0;
xioctl(fd, RTC_SET_TIME, &time);
close(fd);
}
static void set_sysclock_timezone()
{
struct timezone tmzone;
struct timeval tmval;
struct tm *pb;
if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
if (!(pb = localtime(&tmval.tv_sec))) error_exit("localtime failed");
// extern long timezone => defined in header sys/time.h
tmzone.tz_minuteswest = timezone / 60;
if (pb->tm_isdst) tmzone.tz_minuteswest -= 60;
tmzone.tz_dsttime = 0; // daylight saving time is not in effect
if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday");
if (!TT.utc) tmval.tv_sec += tmzone.tz_minuteswest * 60;
if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday");
}
void hwclock_main()
{
// check for UTC
if (!(toys.optflags & FLAG_u)) {
FILE *fp = fopen("/etc/adjtime", "r");
if (fp) {
char *line = NULL;
size_t st;
while (0 < getline(&line, &st, fp)) {
if (!strncmp(line, "UTC", 3)) {
TT.utc = 1;
break;
}
free(line);
}
fclose(fp);
}
} else TT.utc = 1;
if (toys.optflags & FLAG_w) set_hwclock_from_sysclock();
else if (toys.optflags & FLAG_s) set_sysclock_from_hwclock();
else if (toys.optflags & FLAG_t) set_sysclock_timezone();
else if ((toys.optflags & FLAG_r) || (toys.optflags & FLAG_l)
|| !*toys.optargs)
{
time_t tm = get_rtc();
char *s, *pctm = ctime(&tm);
// ctime() is defined as equivalent to asctime(localtime(t)),
// which is defined to overflow its buffer rather than return NULL.
// if (!pctm) error_exit("can't happen");
if ((s = strrchr(pctm, '\n'))) *s = '\0';
// TODO: implement this.
xprintf("%s 0.000000 seconds\n", pctm);
}
}
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