/*
 * rtcwake -- enter a system sleep state until specified wakeup time.
 *
 * 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 <stdio.h>
#include <getopt.h>
#include <fcntl.h>
#include <libgen.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>

#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>

#include <linux/rtc.h>

#include "nls.h"
#include "xalloc.h"
#include "pathnames.h"
#include "usleep.h"
#include "strutils.h"
#include "c.h"
#include "closestream.h"

/* constants from legacy PC/AT hardware */
#define	RTC_PF	0x40
#define	RTC_AF	0x20
#define	RTC_UF	0x10

#define MAX_LINE		1024

#define RTC_PATH		"/sys/class/rtc/%s/device/power/wakeup"
#define SYS_POWER_STATE_PATH	"/sys/power/state"
#define ADJTIME_PATH		"/etc/adjtime"
#define DEFAULT_DEVICE		"/dev/rtc0"
#define DEFAULT_MODE		"standby"

enum ClockMode {
	CM_AUTO,
	CM_UTC,
	CM_LOCAL
};

static unsigned		verbose;
static unsigned		dryrun;
static unsigned		ioctl_aie_on;  /* ioctl(AIE_ON) succeeded */
enum ClockMode		clock_mode = CM_AUTO;

static struct option long_options[] = {
	{"auto",	no_argument,		0, 'a'},
	{"dry-run",	no_argument,		0, 'n'},
	{"local",	no_argument,		0, 'l'},
	{"utc",		no_argument,		0, 'u'},
	{"verbose",	no_argument,		0, 'v'},
	{"version",	no_argument,		0, 'V'},
	{"help",	no_argument,		0, 'h'},
	{"mode",	required_argument,	0, 'm'},
	{"device",	required_argument,	0, 'd'},
	{"seconds",	required_argument,	0, 's'},
	{"time",	required_argument,	0, 't'},
	{0,		0,			0, 0  }
};

static void __attribute__((__noreturn__)) usage(FILE *out)
{
	fputs(USAGE_HEADER, out);
	fprintf(out,
	      _(" %s [options]\n"), program_invocation_short_name);

	fputs(USAGE_OPTIONS, out);
	fputs(_(" -d, --device <device>    select rtc device (rtc0|rtc1|...)\n"
		" -n, --dry-run            does everything, but suspend\n"
		" -l, --local              RTC uses local timezone\n"
		" -m, --mode <mode>        standby|mem|... sleep mode\n"
		" -s, --seconds <seconds>  seconds to sleep\n"
		" -t, --time <time_t>      time to wake\n"
		" -u, --utc                RTC uses UTC\n"
		" -v, --verbose            verbose messages\n"), out);

	printf(USAGE_SEPARATOR);
	printf(USAGE_HELP);
	printf(USAGE_VERSION);

	printf(USAGE_MAN_TAIL("rtcwake(8)"));

	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}

static int is_wakeup_enabled(const char *devname)
{
	char	buf[128], *s;
	FILE	*f;

	/* strip the '/dev/' from the devname here */
	snprintf(buf, sizeof buf, RTC_PATH, devname + strlen("/dev/"));
	f = fopen(buf, "r");
	if (!f) {
		warn(_("cannot open %s"), buf);
		return 0;
	}
	s = fgets(buf, sizeof buf, f);
	fclose(f);
	if (!s)
		return 0;

	s = strchr(buf, '\n');
	if (!s)
		return 0;
	*s = 0;

	/* wakeup events could be disabled or not supported */
	return strcmp(buf, "enabled") == 0;
}

/* all times should be in UTC */
static time_t	sys_time;
static time_t	rtc_time;

static int get_basetimes(int fd)
{
	struct tm	tm;
	struct rtc_time	rtc;

	/* this process works in RTC time, except when working
	 * with the system clock (which always uses UTC).
	 */
	if (clock_mode == CM_UTC)
		setenv("TZ", "UTC", 1);
	tzset();

	/* read rtc and system clocks "at the same time", or as
	 * precisely (+/- a second) as we can read them.
	 */
	if (ioctl(fd, RTC_RD_TIME, &rtc) < 0) {
		warn(_("read rtc time failed"));
		return -1;
	}
	sys_time = time(0);
	if (sys_time == (time_t)-1) {
		warn(_("read system time failed"));
		return -1;
	}

	/* convert rtc_time to normal arithmetic-friendly form,
	 * updating tm.tm_wday as used by asctime().
	 */
	memset(&tm, 0, sizeof tm);
	tm.tm_sec = rtc.tm_sec;
	tm.tm_min = rtc.tm_min;
	tm.tm_hour = rtc.tm_hour;
	tm.tm_mday = rtc.tm_mday;
	tm.tm_mon = rtc.tm_mon;
	tm.tm_year = rtc.tm_year;
	tm.tm_isdst = -1;  /* assume the system knows better than the RTC */
	rtc_time = mktime(&tm);

	if (rtc_time == (time_t)-1) {
		warn(_("convert rtc time failed"));
		return -1;
	}

	if (verbose) {
		/* Unless the system uses UTC, either delta or tzone
		 * reflects a seconds offset from UTC.  The value can
		 * help sort out problems like bugs in your C library.
		 */
		printf("\tdelta   = %ld\n", sys_time - rtc_time);
		printf("\ttzone   = %ld\n", timezone);

		printf("\ttzname  = %s\n", tzname[daylight]);
		gmtime_r(&rtc_time, &tm);
		printf("\tsystime = %ld, (UTC) %s",
				(long) sys_time, asctime(gmtime(&sys_time)));
		printf("\trtctime = %ld, (UTC) %s",
				(long) rtc_time, asctime(&tm));
	}

	return 0;
}

static int setup_alarm(int fd, time_t *wakeup)
{
	struct tm		*tm;
	struct 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 clock_mode == CM_UTC this process's timezone is UTC,
	 * so we'll pass a UTC date to the RTC.
	 *
	 * Else clock_mode == CM_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;

	wake.enabled = 1;

	/* First try the preferred RTC_WKALM_SET */
	if (!dryrun && ioctl(fd, RTC_WKALM_SET, &wake) < 0) {
		wake.enabled = 0;
		/* Fall back on the non-preferred way of setting wakeups; only
		* works for alarms < 24 hours from now */
		if ((rtc_time + (24 * 60 * 60)) > *wakeup) {
			if (ioctl(fd, RTC_ALM_SET, &wake.time) < 0) {
				warn(_("set rtc alarm failed"));
				return -1;
			}
			if (ioctl(fd, RTC_AIE_ON, 0) < 0) {
				warn(_("enable rtc alarm failed"));
				return -1;
			}
			ioctl_aie_on = 1;
		} else {
			warn(_("set rtc wake alarm failed"));
			return -1;
		}
	}

	return 0;
}

static int is_suspend_available(const char *suspend)
{
	int rc;
	char buf[32];
	FILE *f = fopen(SYS_POWER_STATE_PATH, "r");

	if (!f)
		return -1;

	if (fgets(buf, sizeof buf, f) == NULL)
		rc = -1;
	else
		rc = strstr(buf, suspend) != NULL;

	fclose(f);
	return rc;
}

static void suspend_system(const char *suspend)
{
	FILE	*f = fopen(SYS_POWER_STATE_PATH, "w");

	if (!f) {
		warn(_("cannot open %s"), SYS_POWER_STATE_PATH);
		return;
	}

	if (!dryrun) {
		fprintf(f, "%s\n", suspend);
		fflush(f);
	}

	/* this executes after wake from suspend */
	if (close_stream(f))
		errx(EXIT_FAILURE, _("write error"));
}


static int read_clock_mode(void)
{
	FILE *fp;
	char linebuf[MAX_LINE];

	fp = fopen(ADJTIME_PATH, "r");
	if (!fp)
		return -1;

	/* skip first line */
	if (!fgets(linebuf, MAX_LINE, fp)) {
		fclose(fp);
		return -1;
	}

	/* skip second line */
	if (!fgets(linebuf, MAX_LINE, fp)) {
		fclose(fp);
		return -1;
	}

	/* read third line */
	if (!fgets(linebuf, MAX_LINE, fp)) {
		fclose(fp);
		return -1;
	}

	if (strncmp(linebuf, "UTC", 3) == 0)
		clock_mode = CM_UTC;
	else if (strncmp(linebuf, "LOCAL", 5) == 0)
		clock_mode = CM_LOCAL;

	fclose(fp);

	return 0;
}

/**
 * print basic alarm settings
 */
static int print_alarm(int fd)
{
	struct rtc_wkalrm wake;
	struct rtc_time rtc;
	struct tm tm;
	time_t alarm;

	 /* First try the preferred RTC_WKALM_RD */
	if (ioctl(fd, RTC_WKALM_RD, &wake) < 0) {
		/* Fall back on the non-preferred way of reading wakeups; only
		 * works for alarms < 24 hours from now
		 *
		 * set wake.enabled to 1 and determine from value of the year-1
		 * means disabled
		 */
		wake.enabled = 1;
		if (ioctl(fd, RTC_ALM_READ, &wake.time) < 0) {
			warn(_("read rtc alarm failed"));
			return -1;
		}
	}

	if (wake.enabled != 1 || wake.time.tm_year == -1) {
		printf(_("alarm: off\n"));
		return 0;
	}

	rtc = wake.time;

	memset(&tm, 0, sizeof tm);
	tm.tm_sec = rtc.tm_sec;
	tm.tm_min = rtc.tm_min;
	tm.tm_hour = rtc.tm_hour;
	tm.tm_mday = rtc.tm_mday;
	tm.tm_mon = rtc.tm_mon;
	tm.tm_year = rtc.tm_year;
	tm.tm_isdst = -1;  /* assume the system knows better than the RTC */

	alarm = mktime(&tm);
	if (alarm == (time_t)-1) {
		warn(_("convert time failed"));
		return -1;
	}

	/* 0 if both UTC, or expresses diff if RTC in local time */
	alarm += sys_time - rtc_time;

	printf(_("alarm: on  %s"), ctime(&alarm));
	return 0;
}

int main(int argc, char **argv)
{
	char		*devname = DEFAULT_DEVICE;
	unsigned	seconds = 0;
	char		*suspend = DEFAULT_MODE;

	int		rc = EXIT_SUCCESS;
	int		t;
	int		fd;
	time_t		alarm = 0;

	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);
	atexit(close_stdout);

	while ((t = getopt_long(argc, argv, "ahd:lm:ns:t:uVv",
					long_options, NULL)) != EOF) {
		switch (t) {
		case 'a':
			/* CM_AUTO is default */
			break;

		case 'd':
			devname = optarg;
			break;

		case 'l':
			clock_mode = CM_LOCAL;
			break;

			/* what system power mode to use?  for now handle only
			 * standardized mode names; eventually when systems
			 * define their own state names, parse
			 * /sys/power/state.
			 *
			 * "on" is used just to test the RTC alarm mechanism,
			 * bypassing all the wakeup-from-sleep infrastructure.
			 */
		case 'm':
			if (strcmp(optarg, "standby") == 0
					|| strcmp(optarg, "mem") == 0
					|| strcmp(optarg, "disk") == 0
					|| strcmp(optarg, "on") == 0
					|| strcmp(optarg, "no") == 0
					|| strcmp(optarg, "off") == 0
					|| strcmp(optarg, "disable") == 0
					|| strcmp(optarg, "show") == 0
			   ) {
				suspend = optarg;
				break;
			}

			errx(EXIT_FAILURE, _("unrecognized suspend state '%s'"),
									optarg);
			break;

		case 'n':
			dryrun = 1;
			break;

			/* alarm time, seconds-to-sleep (relative) */
		case 's':
			seconds = strtou32_or_err(optarg, _("invalid seconds argument"));
			break;

			/* alarm time, time_t (absolute, seconds since
			 * 1/1 1970 UTC)
			 */
		case 't':
			alarm = strtou32_or_err(optarg, _("invalid time argument"));
			break;

		case 'u':
			clock_mode = CM_UTC;
			break;

		case 'v':
			verbose++;
			break;

		case 'V':
			printf(UTIL_LINUX_VERSION);
			exit(EXIT_SUCCESS);

		case 'h':
			usage(stdout);
		default:
			usage(stderr);
		}
	}

	if (clock_mode == CM_AUTO) {
		if (read_clock_mode() < 0) {
			printf(_("%s: assuming RTC uses UTC ...\n"),
					program_invocation_short_name);
			clock_mode = CM_UTC;
		}
	}
	if (verbose)
		printf(clock_mode == CM_UTC ? _("Using UTC time.\n") :
				_("Using local time.\n"));

	if (!alarm && !seconds && strcmp(suspend,"disable") &&
				  strcmp(suspend,"show")) {

		warnx(_("must provide wake time (see -t and -s options)"));
		usage(stderr);
	}

	/* when devname doesn't start with /dev, append it */
	if (strncmp(devname, "/dev/", strlen("/dev/")) != 0) {
		char *new_devname;

		new_devname = xmalloc(strlen(devname) + strlen("/dev/") + 1);

		strcpy(new_devname, "/dev/");
		strcat(new_devname, devname);
		devname = new_devname;
	}

	if (strcmp(suspend, "on") != 0 && strcmp(suspend, "no") != 0
			&& !is_wakeup_enabled(devname))
		errx(EXIT_FAILURE, _("%s not enabled for wakeup events"), devname);

	/* this RTC must exist and (if we'll sleep) be wakeup-enabled */
#ifdef O_CLOEXEC
	fd = open(devname, O_RDONLY | O_CLOEXEC);
#else
	fd = open(devname, O_RDONLY);
#endif
	if (fd < 0)
		err(EXIT_FAILURE, _("cannot open %s"), devname);

	/* relative or absolute alarm time, normalized to time_t */
	if (get_basetimes(fd) < 0)
		exit(EXIT_FAILURE);
	if (verbose)
		printf(_("alarm %ld, sys_time %ld, rtc_time %ld, seconds %u\n"),
				alarm, sys_time, rtc_time, seconds);

	if (strcmp(suspend, "show") && strcmp(suspend, "disable")) {
		if (strcmp(suspend, "no") && strcmp(suspend, "on") &&
		    strcmp(suspend, "off") && is_suspend_available(suspend) <= 0) {
			errx(EXIT_FAILURE, _("suspend to \"%s\" unavailable"), suspend);
		}

		/* care about alarm setup only if the show|disable
		 * modes are not set
		 */
		if (alarm) {
			if (alarm < sys_time)
				errx(EXIT_FAILURE, _("time doesn't go backward to %s"),
						ctime(&alarm));
			alarm += sys_time - rtc_time;
		} else
			alarm = rtc_time + seconds + 1;

		if (setup_alarm(fd, &alarm) < 0)
			exit(EXIT_FAILURE);

		if (strcmp(suspend, "no") == 0 || strcmp(suspend, "on") == 0)
			printf(_("%s: wakeup using %s at %s"),
				program_invocation_short_name, devname,
				ctime(&alarm));
		else
			printf(_("%s: wakeup from \"%s\" using %s at %s"),
				program_invocation_short_name, suspend, devname,
				ctime(&alarm));
		fflush(stdout);
		usleep(10 * 1000);
	}

	if (strcmp(suspend, "no") == 0) {
		if (verbose)
			printf(_("suspend mode: no; leaving\n"));
		dryrun = 1;	/* to skip disabling alarm at the end */

	} else if (strcmp(suspend, "off") == 0) {
		char *arg[4];
		int i = 0;

		if (verbose)
			printf(_("suspend mode: off; executing %s\n"),
						_PATH_SHUTDOWN);
		arg[i++] = _PATH_SHUTDOWN;
		arg[i++] = "-P";
		arg[i++] = "now";
		arg[i]   = NULL;

		if (!dryrun) {
			execv(arg[0], arg);

			warn(_("unable to execute %s"),	_PATH_SHUTDOWN);
			rc = EXIT_FAILURE;
		}

	} else if (strcmp(suspend, "on") == 0) {
		unsigned long data;

		if (verbose)
			printf(_("suspend mode: on; reading rtc\n"));

		if (!dryrun) {
			do {
				t = read(fd, &data, sizeof data);
				if (t < 0) {
					warn(_("rtc read failed"));
					break;
				}
				if (verbose)
					printf("... %s: %03lx\n", devname, data);
			} while (!(data & RTC_AF));
		}

	} else if (strcmp(suspend, "disable") == 0) {
		/* just break, alarm gets disabled in the end */
		if (verbose)
			printf(_("suspend mode: disable; disabling alarm\n"));

	} else if(strcmp(suspend,"show") == 0) {
		if (verbose)
			printf(_("suspend mode: show; printing alarm info\n"));
		if (print_alarm(fd))
			rc = EXIT_FAILURE;
		dryrun = 1;	/* don't really disable alarm in the end, just show */

	} else {
		if (verbose)
			printf(_("suspend mode: %s; suspending system\n"), suspend);
		sync();
		suspend_system(suspend);
	}

	if (!dryrun && ioctl_aie_on && ioctl(fd, RTC_AIE_OFF, 0) < 0)
		warn(_("disable rtc alarm interrupt failed"));

	close(fd);
	return rc;
}