hwclock: get and set the hwclock

1 files changed, 160 insertions, 0 deletions

diff --git a/toys/pending/hwclock.c b/toys/pending/hwclock.c
new file mode 100644
index 00000000..980d1651
--- /dev/null
+++ b/toys/pending/hwclock.c
@@ -0,0 +1,160 @@
+/* hwclock.c - get and set the hwclock
+ *
+ * Copyright 2014 Bilal Qureshi <bilal.jmi@gmail.com>
+ *
+ * No Standard.
+ *
+USE_HWCLOCK(NEWTOY(hwclock, "f(rtc):u(utc)l(localtime)t(systz)w(systohc)s(hctosys)r(show)[!ul][!rs][!rw][!rt][!sw][!st][!wt]", TOYFLAG_USR|TOYFLAG_BIN))
+
+config HWCLOCK
+  bool "hwclock"
+  default n
+  help
+    usage: hwclock [-r|--show] [-s|--hctosys] [-w|--systohc] [-t|--systz] [-l|--localtime] 
+    [-u|--utc] [-f|--rtc FILE]
+
+    -f FILE Use specified device file (e.g. /dev/rtc2) instead of default
+    -l      Assume hardware clock is kept in localtime
+    -r      Show hardware clock time
+    -s      Set system time from hardware clock
+    -t      Set the system time based on the current timezone 
+    -u      Assume hardware clock is kept in UTC
+    -w      Set hardware clock from system time
+*/
+#define FOR_hwclock
+#include "toys.h"
+#include <linux/rtc.h>
+
+GLOBALS(
+  char *fname;
+
+  int utc;
+)
+
+static int rtc_open(char **dev_rtc, int flag)
+{
+  if (!*dev_rtc) {
+    int fd; 
+
+    if ((fd = open((*dev_rtc = "/dev/rtc"), flag)) != -1) return fd;
+    else if ((fd = open((*dev_rtc = "/dev/rtc0"), flag)) != -1) return fd;
+    else *dev_rtc = "/dev/misc/rtc";
+  }
+  return xopen(*dev_rtc, flag);
+}
+
+static time_t get_rtc()
+{
+  struct tm time;
+  time_t tm;
+  char *ptz_old = NULL;
+  int fd = rtc_open(&TT.fname, O_RDONLY);
+
+  memset(&time, 0, sizeof(time));
+  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(&TT.fname, 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");
+}
+
+static void rtc_adjtime()
+{
+  char *line = NULL;
+  int fd = open("/etc/adjtime", O_RDONLY);
+
+  if (fd != -1) {
+    for (; (line = get_line(fd)); free(line)) {
+      if (!strncmp(line, "UTC", 3)) {
+        TT.utc = 1;
+        break;
+      }
+    }
+    close(fd);
+  }
+}
+
+static void display_hwclock()
+{
+  time_t tm = get_rtc();
+  char *s, *pctm = ctime(&tm);
+
+  if (pctm) {
+    if ((s = strrchr(pctm, '\n'))) *s = '\0';
+    xprintf("%s  0.000000 seconds\n", pctm);
+  } else error_exit("failed to convert a time value to a date & time string");
+}
+
+void hwclock_main()
+{
+  (!(toys.optflags & FLAG_u)) ? rtc_adjtime() : (TT.utc = 1); // check for UTC
+  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) display_hwclock();
+  else {
+    toys.exithelp++;
+    error_exit("invalid option '%s'", *toys.optargs);
+  }
+}