/* SPDX-License-Identifier: ISC */
#include <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>

#include <sys/reboot.h>
#include <linux/reboot.h>

#define FL_FORCE 0x01
#define FL_NOSYNC 0x02

static const struct option options[] = {
	{ "help", no_argument, NULL, 'h' },
	{ "poweroff", no_argument, NULL, 'p' },
	{ "reboot", no_argument, NULL, 'r' },
	{ "force", no_argument, NULL, 'f' },
	{ "no-sync", no_argument, NULL, 'n' },
	{ NULL, 0, NULL, 0 },
};

static const char *shortopt = "hprfn";

static const char *defact_str = "power-off";
static int defact = RB_POWER_OFF;

static __attribute__((noreturn)) void usage(const char *progname, int status)
{
	fprintf(status == EXIT_SUCCESS ? stdout : stderr,
"%s [OPTIONS...]\n\n"
"Perform a system shutdown or reboot.\n\n"
"   -h, --help      Display this help text and exit.\n"
"   -V, --version   Display version information and exit.\n"
"   -p, --poweroff  Power-off the machine.\n"
"   -r, --reboot    Reboot the machine.\n"
"   -f, --force     Force immediate power-off or reboot. Do not contact the\n"
"                   init system.\n"
"   -n, --no-sync   Don't sync storage media before power-off or reboot.\n\n"
"If no option is specified, the default action is %s.\n",
	progname, defact_str);
	exit(status);
}

int main(int argc, char **argv)
{
	int c, ret, flags = 0;
	char *ptr;

	ptr = strrchr(argv[0], '/');
	ptr = (ptr == NULL) ? argv[0] : (ptr + 1);

	if (strcmp(ptr, "reboot") == 0) {
		defact_str = "reboot";
		defact = RB_AUTOBOOT;
	}

	while (1) {
		c = getopt_long(argc, argv, shortopt, options, NULL);
		if (c == -1)
			break;

		switch (c) {
		case 'f':
			flags |= FL_FORCE;
			break;
		case 'n':
			flags |= FL_NOSYNC;
			break;
		case 'p':
			defact = RB_POWER_OFF;
			break;
		case 'r':
			defact = RB_AUTOBOOT;
			break;
		case 'h':
			usage(ptr, EXIT_SUCCESS);
		default:
			usage(ptr, EXIT_FAILURE);
		}
	}

	if (flags & FL_FORCE) {
		if (!(flags & FL_NOSYNC))
			sync();
		reboot(defact);
		perror("reboot system call");
		return EXIT_FAILURE;
	}

	switch (defact) {
	case RB_AUTOBOOT:
		ret = kill(1, SIGINT);
		break;
	case RB_POWER_OFF:
		ret = kill(1, SIGTERM);
		break;
	default:
		return EXIT_SUCCESS;
	}

	if (ret) {
		perror("sending signal to init");
		return EXIT_FAILURE;
	}
	return EXIT_SUCCESS;
}