util-linux/hwclock.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini hwclock implementation for busybox
   4  *
   5  * Copyright (C) 2002 Robert Griebl <griebl@gmx.de>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8 */
   9
  10 #include <sys/utsname.h>
  11 #include <getopt.h>
  12 #include "libbb.h"
  13
  14 /* Copied from linux/rtc.h to eliminate the kernel dependency */
  15 struct linux_rtc_time {
  16         int tm_sec;
  17         int tm_min;
  18         int tm_hour;
  19         int tm_mday;
  20         int tm_mon;
  21         int tm_year;
  22         int tm_wday;
  23         int tm_yday;
  24         int tm_isdst;
  25 };
  26
  27 #define RTC_SET_TIME   _IOW('p', 0x0a, struct linux_rtc_time) /* Set RTC time    */
  28 #define RTC_RD_TIME    _IOR('p', 0x09, struct linux_rtc_time) /* Read RTC time   */
  29
  30 #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
  31 # ifndef _GNU_SOURCE
  32 #  define _GNU_SOURCE
  33 # endif
  34 #endif
  35
  36 static const char *rtcname;
  37
  38 static int xopen_rtc(int flags)
  39 {
  40         int rtc;
  41
  42         if (!rtcname) {
  43                 rtc = open("/dev/rtc", flags);
  44                 if (rtc >= 0)
  45                         return rtc;
  46                 rtc = open("/dev/rtc0", flags);
  47                 if (rtc >= 0)
  48                         return rtc;
  49                 rtcname = "/dev/misc/rtc";
  50         }
  51         return xopen(rtcname, flags);
  52 }
  53
  54 static time_t read_rtc(int utc)
  55 {
  56         struct tm tm;
  57         char *oldtz = 0;
  58         time_t t = 0;
  59         int rtc = xopen_rtc(O_RDONLY);
  60
  61         memset(&tm, 0, sizeof(struct tm));
  62         xioctl(rtc, RTC_RD_TIME, &tm);
  63         tm.tm_isdst = -1; /* not known */
  64
  65         close(rtc);
  66
  67         if (utc) {
  68                 oldtz = getenv("TZ");
  69                 putenv((char*)"TZ=UTC0");
  70                 tzset();
  71         }
  72
  73         t = mktime(&tm);
  74
  75         if (utc) {
  76                 unsetenv("TZ");
  77                 if (oldtz)
  78                         putenv(oldtz - 3);
  79                 tzset();
  80         }
  81         return t;
  82 }
  83
  84 static void write_rtc(time_t t, int utc)
  85 {
  86         struct tm tm;
  87         int rtc = xopen_rtc(O_WRONLY);
  88
  89         tm = *(utc ? gmtime(&t) : localtime(&t));
  90         tm.tm_isdst = 0;
  91
  92         xioctl(rtc, RTC_SET_TIME, &tm);
  93
  94         close(rtc);
  95 }
  96
  97 static void show_clock(int utc)
  98 {
  99         //struct tm *ptm;
 100         time_t t;
 101         char *cp;
 102
 103         t = read_rtc(utc);
 104         //ptm = localtime(&t);  /* Sets 'tzname[]' */
 105
 106         cp = ctime(&t);
 107         if (cp[0])
 108                 cp[strlen(cp) - 1] = '\0';
 109
 110         //printf("%s  %.6f seconds %s\n", cp, 0.0, utc ? "" : (ptm->tm_isdst ? tzname[1] : tzname[0]));
 111         printf("%s  0.000000 seconds\n", cp);
 112 }
 113
 114 static void to_sys_clock(int utc)
 115 {
 116         struct timeval tv;
 117         const struct timezone tz = { timezone/60 - 60*daylight, 0 };
 118
 119         tv.tv_sec = read_rtc(utc);
 120         tv.tv_usec = 0;
 121         if (settimeofday(&tv, &tz))
 122                 bb_perror_msg_and_die("settimeofday() failed");
 123 }
 124
 125 static void from_sys_clock(int utc)
 126 {
 127         struct timeval tv;
 128
 129         gettimeofday(&tv, NULL);
 130         //if (gettimeofday(&tv, NULL))
 131         //      bb_perror_msg_and_die("gettimeofday() failed");
 132         write_rtc(tv.tv_sec, utc);
 133 }
 134
 135 #if ENABLE_FEATURE_HWCLOCK_ADJTIME_FHS
 136 # define ADJTIME_PATH "/var/lib/hwclock/adjtime"
 137 #else
 138 # define ADJTIME_PATH "/etc/adjtime"
 139 #endif
 140 static int check_utc(void)
 141 {
 142         int utc = 0;
 143         FILE *f = fopen(ADJTIME_PATH, "r");
 144
 145         if (f) {
 146                 RESERVE_CONFIG_BUFFER(buffer, 128);
 147
 148                 while (fgets(buffer, sizeof(buffer), f)) {
 149                         int len = strlen(buffer);
 150
 151                         while (len && isspace(buffer[len - 1]))
 152                                 len--;
 153
 154                         buffer[len] = 0;
 155
 156                         if (strncmp(buffer, "UTC", 3) == 0) {
 157                                 utc = 1;
 158                                 break;
 159                         }
 160                 }
 161                 fclose(f);
 162                 RELEASE_CONFIG_BUFFER(buffer);
 163         }
 164         return utc;
 165 }
 166
 167 #define HWCLOCK_OPT_LOCALTIME   0x01
 168 #define HWCLOCK_OPT_UTC         0x02
 169 #define HWCLOCK_OPT_SHOW        0x04
 170 #define HWCLOCK_OPT_HCTOSYS     0x08
 171 #define HWCLOCK_OPT_SYSTOHC     0x10
 172 #define HWCLOCK_OPT_RTCFILE     0x20
 173
 174 int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 175 int hwclock_main(int argc, char **argv)
 176 {
 177         unsigned opt;
 178         int utc;
 179
 180 #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
 181         static const char hwclock_longopts[] ALIGN1 =
 182                 "localtime\0" No_argument "l"
 183                 "utc\0"       No_argument "u"
 184                 "show\0"      No_argument "r"
 185                 "hctosys\0"   No_argument "s"
 186                 "systohc\0"   No_argument "w"
 187                 "file\0"      Required_argument "f"
 188                 ;
 189         applet_long_options = hwclock_longopts;
 190 #endif
 191         opt_complementary = "r--ws:w--rs:s--wr:l--u:u--l";
 192         opt = getopt32(argv, "lurswf:", &rtcname);
 193
 194         /* If -u or -l wasn't given check if we are using utc */
 195         if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME))
 196                 utc = opt & HWCLOCK_OPT_UTC;
 197         else
 198                 utc = check_utc();
 199
 200         if (opt & HWCLOCK_OPT_HCTOSYS) {
 201                 to_sys_clock(utc);
 202                 return 0;
 203         }
 204         if (opt & HWCLOCK_OPT_SYSTOHC) {
 205                 from_sys_clock(utc);
 206                 return 0;
 207         }
 208         /* default HWCLOCK_OPT_SHOW */
 209         show_clock(utc);
 210         return 0;
 211 }