hwclock: implement --systz

function                                             old     new   delta
hwclock_main                                         324     434    +110
packed_usage                                       28220   28259     +39
static.hwclock_longopts                               53      60      +7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 156/0)             Total: 156 bytes

Signed-off-by: Davide Cavalca <davide@geexbox.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 59 insertions, 5 deletions

diff --git a/util-linux/hwclock.c b/util-linux/hwclock.c
index 922dd0578..54e97e5bb 100644
--- a/util-linux/hwclock.c
+++ b/util-linux/hwclock.c
@@ -223,12 +223,63 @@ static void from_sys_clock(const char **pp_rtcname, int utc)
                 close(rtc);
 }
 
+/*
+ * At system boot, kernel may set system time from RTC,
+ * but it knows nothing about timezones. If RTC is in local time,
+ * then system time is wrong - it is offset by timezone.
+ * This option corrects system time if RTC is in local time,
+ * and (always) sets in-kernel timezone.
+ *
+ * This is an alternate option to --hctosys that does not read the
+ * hardware clock.
+ */
+static void set_system_clock_timezone(int utc)
+{
+        struct timeval tv;
+        struct tm *broken;
+        struct timezone tz;
+
+        gettimeofday(&tv, NULL);
+        broken = localtime(&tv.tv_sec);
+        tz.tz_minuteswest = timezone / 60;
+        if (broken->tm_isdst)
+                tz.tz_minuteswest -= 60;
+        tz.tz_dsttime = 0;
+        gettimeofday(&tv, NULL);
+        if (!utc)
+                tv.tv_sec += tz.tz_minuteswest * 60;
+        if (settimeofday(&tv, &tz))
+                bb_perror_msg_and_die("settimeofday");
+}
+
+//usage:#define hwclock_trivial_usage
+//usage:        IF_FEATURE_HWCLOCK_LONG_OPTIONS(
+//usage:       "[-r|--show] [-s|--hctosys] [-w|--systohc] [-t|--systz]"
+//usage:       " [-l|--localtime] [-u|--utc]"
+//usage:       " [-f|--rtc FILE]"
+//usage:        )
+//usage:        IF_NOT_FEATURE_HWCLOCK_LONG_OPTIONS(
+//usage:       "[-r] [-s] [-w] [-t] [-l] [-u] [-f FILE]"
+//usage:        )
+//usage:#define hwclock_full_usage "\n\n"
+//usage:       "Query and set hardware clock (RTC)\n"
+//usage:     "\nOptions:"
+//usage:     "\n        -r      Show hardware clock time"
+//usage:     "\n        -s      Set system time from hardware clock"
+//usage:     "\n        -w      Set hardware clock from system time"
+//usage:     "\n        -t      Set in-kernel timezone, correct system time"
+//usage:     "\n                if hardware clock is in local time"
+//usage:     "\n        -u      Hardware clock is in UTC"
+//usage:     "\n        -l      Hardware clock is in local time"
+//usage:     "\n        -f FILE Use specified device (e.g. /dev/rtc2)"
+
 #define HWCLOCK_OPT_LOCALTIME   0x01
 #define HWCLOCK_OPT_UTC         0x02
 #define HWCLOCK_OPT_SHOW        0x04
 #define HWCLOCK_OPT_HCTOSYS     0x08
 #define HWCLOCK_OPT_SYSTOHC     0x10
-#define HWCLOCK_OPT_RTCFILE     0x20
+#define HWCLOCK_OPT_SYSTZ       0x20
+#define HWCLOCK_OPT_RTCFILE     0x40
 
 int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int hwclock_main(int argc UNUSED_PARAM, char **argv)
@@ -239,17 +290,18 @@ int hwclock_main(int argc UNUSED_PARAM, char **argv)
 
 #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS
         static const char hwclock_longopts[] ALIGN1 =
-                "localtime\0" No_argument "l"
+                "localtime\0" No_argument "l" /* short opt is non-standard */
                 "utc\0"       No_argument "u"
                 "show\0"      No_argument "r"
                 "hctosys\0"   No_argument "s"
                 "systohc\0"   No_argument "w"
-                "file\0"      Required_argument "f"
+                "systz\0"     No_argument "t" /* short opt is non-standard */
+                "rtc\0"       Required_argument "f"
                 ;
         applet_long_options = hwclock_longopts;
 #endif
-        opt_complementary = "r--ws:w--rs:s--wr:l--u:u--l";
-        opt = getopt32(argv, "lurswf:", &rtcname);
+        opt_complementary = "r--wst:w--rst:s--wrt:t--rsw:l--u:u--l";
+        opt = getopt32(argv, "lurswtf:", &rtcname);
 
         /* If -u or -l wasn't given check if we are using utc */
         if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME))
@@ -261,6 +313,8 @@ int hwclock_main(int argc UNUSED_PARAM, char **argv)
                 to_sys_clock(&rtcname, utc);
         else if (opt & HWCLOCK_OPT_SYSTOHC)
                 from_sys_clock(&rtcname, utc);
+        else if (opt & HWCLOCK_OPT_SYSTZ)
+                set_system_clock_timezone(utc);
         else
                 /* default HWCLOCK_OPT_SHOW */
                 show_clock(&rtcname, utc);