split some rtc funcs out of hwclock and into an rtc header/lib so that the new rtcwake applet as well as hwclock can utilize the same code
diff --git a/util-linux/rtcwake.c b/util-linux/rtcwake.c
new file mode 100644
index 0000000..718f43d
--- /dev/null
+++ b/util-linux/rtcwake.c
@@ -0,0 +1,209 @@
+/*
+ * rtcwake -- enter a system sleep state until specified wakeup time.
+ *
+ * This version was taken from util-linux and scrubbed down for busybox.
+ *
+ * This uses cross-platform Linux interfaces to enter a system sleep state,
+ * and leave it no later than a specified time. It uses any RTC framework
+ * driver that supports standard driver model wakeup flags.
+ *
+ * This is normally used like the old "apmsleep" utility, to wake from a
+ * suspend state like ACPI S1 (standby) or S3 (suspend-to-RAM). Most
+ * platforms can implement those without analogues of BIOS, APM, or ACPI.
+ *
+ * On some systems, this can also be used like "nvram-wakeup", waking
+ * from states like ACPI S4 (suspend to disk). Not all systems have
+ * persistent media that are appropriate for such suspend modes.
+ *
+ * The best way to set the system's RTC is so that it holds the current
+ * time in UTC. Use the "-l" flag to tell this program that the system
+ * RTC uses a local timezone instead (maybe you dual-boot MS-Windows).
+ * That flag should not be needed on systems with adjtime support.
+ */
+
+#include "libbb.h"
+#include "rtc_.h"
+
+#define SYS_RTC_PATH "/sys/class/rtc/%s/device/power/wakeup"
+#define SYS_POWER_PATH "/sys/power/state"
+#define DEFAULT_MODE "suspend"
+
+static time_t rtc_time;
+
+static int may_wakeup(const char *rtcname)
+{
+ ssize_t ret;
+ char buf[128];
+
+ /* strip the '/dev/' from the rtcname here */
+ if (!strncmp(rtcname, "/dev/", 5))
+ rtcname += 5;
+
+ snprintf(buf, sizeof(buf), SYS_RTC_PATH, rtcname);
+ ret = open_read_close(buf, buf, sizeof(buf));
+ if (ret < 0)
+ return 0;
+
+ /* wakeup events could be disabled or not supported */
+ return strcmp(buf, "enabled\n") == 0;
+}
+
+static void setup_alarm(int fd, time_t *wakeup)
+{
+ struct tm *tm;
+ struct linux_rtc_wkalrm wake;
+
+ /* The wakeup time is in POSIX time (more or less UTC).
+ * Ideally RTCs use that same time; but PCs can't do that
+ * if they need to boot MS-Windows. Messy...
+ *
+ * When running in utc mode this process's timezone is UTC,
+ * so we'll pass a UTC date to the RTC.
+ *
+ * Else mode is local so the time given to the RTC
+ * will instead use the local time zone.
+ */
+ tm = localtime(wakeup);
+
+ wake.time.tm_sec = tm->tm_sec;
+ wake.time.tm_min = tm->tm_min;
+ wake.time.tm_hour = tm->tm_hour;
+ wake.time.tm_mday = tm->tm_mday;
+ wake.time.tm_mon = tm->tm_mon;
+ wake.time.tm_year = tm->tm_year;
+ /* wday, yday, and isdst fields are unused by Linux */
+ wake.time.tm_wday = -1;
+ wake.time.tm_yday = -1;
+ wake.time.tm_isdst = -1;
+
+ /* many rtc alarms only support up to 24 hours from 'now',
+ * so use the "more than 24 hours" request only if we must
+ */
+ if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
+ xioctl(fd, RTC_ALM_SET, &wake.time);
+ xioctl(fd, RTC_AIE_ON, 0);
+ } else {
+ /* avoid an extra AIE_ON call */
+ wake.enabled = 1;
+ xioctl(fd, RTC_WKALM_SET, &wake);
+ }
+}
+
+static void suspend_system(const char *suspend)
+{
+ FILE *f = xfopen(SYS_POWER_PATH, "w");
+ fprintf(f, "%s\n", suspend);
+ fflush(f);
+ /* this executes after wake from suspend */
+ fclose(f);
+}
+
+#define RTCWAKE_OPT_AUTO 0x01
+#define RTCWAKE_OPT_LOCAL 0x02
+#define RTCWAKE_OPT_UTC 0x04
+#define RTCWAKE_OPT_DEVICE 0x08
+#define RTCWAKE_OPT_SUSPEND_MODE 0x10
+#define RTCWAKE_OPT_SECONDS 0x20
+#define RTCWAKE_OPT_TIME 0x40
+
+int rtcwake_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int rtcwake_main(int argc, char **argv)
+{
+ unsigned opt;
+ const char *rtcname = NULL;
+ const char *suspend;
+ const char *opt_seconds;
+ const char *opt_time;
+
+ time_t sys_time;
+ time_t alarm_time = 0;
+ unsigned seconds = 0;
+ int utc = -1;
+ int fd;
+
+#if ENABLE_GETOPT_LONG
+ static const char rtcwake_longopts[] ALIGN1 =
+ "auto\0" No_argument "a"
+ "local\0" No_argument "l"
+ "utc\0" No_argument "u"
+ "device\0" Required_argument "d"
+ "mode\0" Required_argument "m"
+ "seconds\0" Required_argument "s"
+ "time\0" Required_argument "t"
+ ;
+ applet_long_options = rtcwake_longopts;
+ }
+#endif
+ opt = getopt32(argv, "alud:m:s:t:", &rtcname, &suspend, &opt_seconds, &opt_time);
+
+ /* this is the default
+ if (opt & RTCWAKE_OPT_AUTO)
+ utc = -1;
+ */
+ if (opt & (RTCWAKE_OPT_UTC | RTCWAKE_OPT_LOCAL))
+ utc = opt & RTCWAKE_OPT_UTC;
+ if (!(opt & RTCWAKE_OPT_SUSPEND_MODE))
+ suspend = DEFAULT_MODE;
+ if (opt & RTCWAKE_OPT_SECONDS)
+ /* alarm time, seconds-to-sleep (relative) */
+ seconds = xatoi(opt_seconds);
+ if (opt & RTCWAKE_OPT_TIME)
+ /* alarm time, time_t (absolute, seconds since 1/1 1970 UTC) */
+ alarm_time = xatoi(opt_time);
+
+ if (!alarm_time && !seconds)
+ bb_error_msg_and_die("must provide wake time");
+
+ if (utc == -1)
+ utc = rtc_adjtime_is_utc();
+
+ /* the rtcname is relative to /dev */
+ xchdir("/dev");
+
+ if (strcmp(suspend, "on") != 0 && !may_wakeup(rtcname))
+ bb_error_msg_and_die("%s not enabled for wakeup events", rtcname);
+
+ /* this RTC must exist and (if we'll sleep) be wakeup-enabled */
+ fd = rtc_xopen(rtcname, O_RDONLY);
+
+ /* relative or absolute alarm time, normalized to time_t */
+ sys_time = time(0);
+ if (sys_time == (time_t)-1)
+ bb_perror_msg_and_die("read system time");
+ rtc_time = rtc_read_time(fd, utc);
+
+ if (alarm_time) {
+ if (alarm_time < sys_time)
+ bb_error_msg_and_die("time doesn't go backward to %s", ctime(&alarm_time));
+ alarm_time += sys_time - rtc_time;
+ } else
+ alarm_time = rtc_time + seconds + 1;
+ setup_alarm(fd, &alarm_time);
+
+ sync();
+ printf("wakeup from \"%s\" at %s", suspend, ctime(&alarm_time));
+ fflush(stdout);
+ usleep(10 * 1000);
+
+ if (!strcmp(suspend, "on"))
+ suspend_system(suspend);
+ else {
+ /* "fake" suspend ... we'll do the delay ourselves */
+ unsigned long data;
+
+ do {
+ ssize_t ret = safe_read(fd, &data, sizeof(data));
+ if (ret < 0) {
+ bb_perror_msg("rtc read");
+ break;
+ }
+ } while (!(data & RTC_AF));
+ }
+
+ xioctl(fd, RTC_AIE_OFF, 0);
+
+ if (ENABLE_FEATURE_CLEAN_UP)
+ close(fd);
+
+ return EXIT_SUCCESS;
+}