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

1 files changed, 209 insertions, 0 deletions

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;
+}