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	hwclock.c - ubase - suckless linux base utils
	git clone git://git.suckless.org/ubase
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	---
	hwclock.c (2616B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <sys/ioctl.h>
	3 #include <sys/stat.h>
	4 #include <sys/time.h>
	5 #include <sys/types.h>
	6
	7 #include <fcntl.h>
	8 #include <stdio.h>
	9 #include <stdlib.h>
	10 #include <string.h>
	11 #include <time.h>
	12 #include <unistd.h>
	13
	14 #include "rtc.h"
	15 #include "util.h"
	16
	17 static void
	18 readrtctm(struct tm *tm, int fd)
	19 {
	20 struct rtc_time rt;
	21
	22 memset(&rt, 0, sizeof(rt));
	23 if (ioctl(fd, RTC_RD_TIME, &rt) < 0)
	24 eprintf("RTC_RD_TIME:");
	25 tm->tm_sec = rt.tm_sec;
	26 tm->tm_min = rt.tm_min;
	27 tm->tm_hour = rt.tm_hour;
	28 tm->tm_mday = rt.tm_mday;
	29 tm->tm_mon = rt.tm_mon;
	30 tm->tm_year = rt.tm_year;
	31 tm->tm_wday = rt.tm_wday;
	32 tm->tm_yday = rt.tm_yday;
	33 tm->tm_isdst = rt.tm_isdst;
	34 }
	35
	36 static void
	37 writertctm(struct tm *tm, int fd)
	38 {
	39 struct rtc_time rt;
	40
	41 rt.tm_sec = tm->tm_sec;
	42 rt.tm_min = tm->tm_min;
	43 rt.tm_hour = tm->tm_hour;
	44 rt.tm_mday = tm->tm_mday;
	45 rt.tm_mon = tm->tm_mon;
	46 rt.tm_year = tm->tm_year;
	47 rt.tm_wday = tm->tm_wday;
	48 rt.tm_yday = tm->tm_yday;
	49 rt.tm_isdst = tm->tm_isdst;
	50 if (ioctl(fd, RTC_SET_TIME, &rt) < 0)
	51 eprintf("RTC_SET_TIME:");
	52 }
	53
	54 static void
	55 show(char *dev)
	56 {
	57 struct tm tm;
	58 time_t t;
	59 int fd;
	60
	61 fd = open(dev, O_RDONLY);
	62 if (fd < 0)
	63 eprintf("open %s:", dev);
	64 readrtctm(&tm, fd);
	65 t = mktime(&tm);
	66 printf("%s", asctime(localtime(&t)));
	67 close(fd);
	68 }
	69
	70 static void
	71 hctosys(char *dev)
	72 {
	73 struct timeval tv;
	74 struct tm tm;
	75 int r;
	76 int fd;
	77
	78 fd = open(dev, O_RDONLY);
	79 if (fd < 0)
	80 eprintf("open %s:", dev);
	81 readrtctm(&tm, fd);
	82 tv.tv_sec = mktime(&tm);
	83 tv.tv_usec = 0;
	84 r = settimeofday(&tv, NULL);
	85 if (r < 0)
	86 eprintf("settimeofday:");
	87 close(fd);
	88 }
	89
	90 static void
	91 systohc(char *dev)
	92 {
	93 struct timeval tv;
	94 struct tm *tm;
	95 time_t t;
	96 int fd;
	97
	98 fd = open(dev, O_WRONLY);
	99 if (fd < 0)
	100 eprintf("open %s:", dev);
	101 gettimeofday(&tv, NULL);
	102 t = tv.tv_sec;
	103 tm = gmtime(&t);
	104 weprintf("warning: assuming UTC for systohc\n");
	105 writertctm(tm, fd);
	106 close(fd);
	107 }
	108
	109 static void
	110 usage(void)
	111 {
	112 eprintf("usage: %s [-rsw] [-u] [dev]\n", argv0);
	113 }
	114
	115 int
	116 main(int argc, char *argv[])
	117 {
	118 char *dev = "/dev/rtc";
	119 int rflag = 0;
	120 int sflag = 0;
	121 int wflag = 0;
	122
	123 ARGBEGIN {
	124 case 'r':
	125 rflag = 1;
	126 break;
	127 case 's':
	128 sflag = 1;
	129 break;
	130 case 'w':
	131 wflag = 1;
	132 break;
	133 case 'u':
	134 break;
	135 default:
	136 usage();
	137 } ARGEND;
	138
	139 if (argc > 1)
	140 usage();
	141 else if (argc == 1)
	142 dev = argv[0];
	143
	144 if ((rflag ^ sflag ^ wflag) == 0)
	145 eprintf("missing or incompatible function\n");
	146
	147 /* Only UTC support at the moment */
	148 setenv("TZ", "UTC0", 1);
	149 tzset();
	150
	151 if (rflag == 1)
	152 show(dev);
	153 else if (sflag == 1)
	154 hctosys(dev);
	155 else if (wflag == 1)
	156 systohc(dev);
	157
	158 return 0;
	159