libbb/rtc.c

   1 /*
   2  * Common RTC functions
   3  *
   4  * Licensed under GPLv2, see file LICENSE in this source tree.
   5  */
   6
   7 #include "libbb.h"
   8 #include "rtc_.h"
   9
  10 #if ENABLE_FEATURE_HWCLOCK_ADJTIME_FHS
  11 # define ADJTIME_PATH "/var/lib/hwclock/adjtime"
  12 #else
  13 # define ADJTIME_PATH "/etc/adjtime"
  14 #endif
  15
  16 int FAST_FUNC rtc_adjtime_is_utc(void)
  17 {
  18         int utc = 0;
  19         FILE *f = fopen_for_read(ADJTIME_PATH);
  20
  21         if (f) {
  22                 char buffer[128];
  23
  24                 while (fgets(buffer, sizeof(buffer), f)) {
  25                         if (strncmp(buffer, "UTC", 3) == 0) {
  26                                 utc = 1;
  27                                 break;
  28                         }
  29                 }
  30                 fclose(f);
  31         }
  32
  33         return utc;
  34 }
  35
  36 int FAST_FUNC rtc_xopen(const char **default_rtc, int flags)
  37 {
  38         int rtc;
  39
  40         if (!*default_rtc) {
  41                 *default_rtc = "/dev/rtc";
  42                 rtc = open(*default_rtc, flags);
  43                 if (rtc >= 0)
  44                         return rtc;
  45                 *default_rtc = "/dev/rtc0";
  46                 rtc = open(*default_rtc, flags);
  47                 if (rtc >= 0)
  48                         return rtc;
  49                 *default_rtc = "/dev/misc/rtc";
  50         }
  51
  52         return xopen(*default_rtc, flags);
  53 }
  54
  55 void FAST_FUNC rtc_read_tm(struct tm *ptm, int fd)
  56 {
  57         memset(ptm, 0, sizeof(*ptm));
  58         xioctl(fd, RTC_RD_TIME, ptm);
  59         ptm->tm_isdst = -1; /* "not known" */
  60 }
  61
  62 time_t FAST_FUNC rtc_tm2time(struct tm *ptm, int utc)
  63 {
  64         char *oldtz = oldtz; /* for compiler */
  65         time_t t;
  66
  67         if (utc) {
  68                 oldtz = getenv("TZ");
  69                 putenv((char*)"TZ=UTC0");
  70                 tzset();
  71         }
  72
  73         t = mktime(ptm);
  74
  75         if (utc) {
  76                 unsetenv("TZ");
  77                 if (oldtz)
  78                         putenv(oldtz - 3);
  79                 tzset();
  80         }
  81
  82         return t;
  83 }