busybox/init/halt.c

/* vi: set sw=4 ts=4: */
/*
 * Poweroff reboot and halt, oh my.
 *
 * Copyright 2006 by Rob Landley <rob@landley.net>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
//config:config HALT
//config:	bool "halt (4 kb)"
//config:	default y
//config:	help
//config:	Stop all processes and halt the system.
//config:
//config:config POWEROFF
//config:	bool "poweroff (4 kb)"
//config:	default y
//config:	help
//config:	Stop all processes and power off the system.
//config:
//config:config REBOOT
//config:	bool "reboot (4 kb)"
//config:	default y
//config:	help
//config:	Stop all processes and reboot the system.
//config:
//config:config FEATURE_WAIT_FOR_INIT
//config:	bool "Before signaling init, make sure it is ready for it"
//config:	default y
//config:	depends on HALT || POWEROFF || REBOOT
//config:	help
//config:	In rare cases, poweroff may be commanded by firmware to OS
//config:	even before init process exists. On Linux, this spawns
//config:	"/sbin/poweroff" very early. This option adds code
//config:	which checks that init is ready to receive poweroff
//config:	commands. Code size increase of ~80 bytes.
//config:
//config:config FEATURE_CALL_TELINIT
//config:	bool "Call telinit on shutdown and reboot"
//config:	default y
//config:	depends on (HALT || POWEROFF || REBOOT) && !INIT
//config:	help
//config:	Call an external program (normally telinit) to facilitate
//config:	a switch to a proper runlevel.
//config:
//config:	This option is only available if you selected halt and friends,
//config:	but did not select init.
//config:
//config:config TELINIT_PATH
//config:	string "Path to telinit executable"
//config:	default "/sbin/telinit"
//config:	depends on FEATURE_CALL_TELINIT
//config:	help
//config:	When busybox halt and friends have to call external telinit
//config:	to facilitate proper shutdown, this path is to be used when
//config:	locating telinit executable.

//applet:IF_HALT(APPLET(halt, BB_DIR_SBIN, BB_SUID_DROP))
//                   APPLET_ODDNAME:name      main  location     suid_type     help
//applet:IF_POWEROFF(APPLET_ODDNAME(poweroff, halt, BB_DIR_SBIN, BB_SUID_DROP, poweroff))
//applet:IF_REBOOT(  APPLET_ODDNAME(reboot,   halt, BB_DIR_SBIN, BB_SUID_DROP, reboot))

//kbuild:lib-$(CONFIG_HALT) += halt.o
//kbuild:lib-$(CONFIG_POWEROFF) += halt.o
//kbuild:lib-$(CONFIG_REBOOT) += halt.o

//usage:#define halt_trivial_usage
//usage:       "[-d DELAY] [-n] [-f]" IF_FEATURE_WTMP(" [-w]")
//usage:#define halt_full_usage "\n\n"
//usage:       "Halt the system\n"
//usage:     "\n	-d SEC	Delay interval"
//usage:     "\n	-n	Do not sync"
//usage:     "\n	-f	Force (don't go through init)"
//usage:	IF_FEATURE_WTMP(
//usage:     "\n	-w	Only write a wtmp record"
//usage:	)
//usage:
//usage:#define poweroff_trivial_usage
//usage:       "[-d DELAY] [-n] [-f]"
//usage:#define poweroff_full_usage "\n\n"
//usage:       "Halt and shut off power\n"
//usage:     "\n	-d SEC	Delay interval"
//usage:     "\n	-n	Do not sync"
//usage:     "\n	-f	Force (don't go through init)"
//usage:
//usage:#define reboot_trivial_usage
//usage:       "[-d DELAY] [-n] [-f]"
//usage:#define reboot_full_usage "\n\n"
//usage:       "Reboot the system\n"
//usage:     "\n	-d SEC	Delay interval"
//usage:     "\n	-n	Do not sync"
//usage:     "\n	-f	Force (don't go through init)"

#include "libbb.h"
#include "reboot.h"

#if ENABLE_FEATURE_WTMP
#include <sys/utsname.h>

static void write_wtmp(void)
{
	struct utmpx utmp;
	struct utsname uts;
	/* "man utmp" says wtmp file should *not* be created automagically */
	/*if (access(bb_path_wtmp_file, R_OK|W_OK) == -1) {
		close(creat(bb_path_wtmp_file, 0664));
	}*/
	memset(&utmp, 0, sizeof(utmp));
	utmp.ut_tv.tv_sec = time(NULL);
	strcpy(utmp.ut_user, "shutdown"); /* it is wide enough */
	utmp.ut_type = RUN_LVL;
	utmp.ut_id[0] = '~'; utmp.ut_id[1] = '~'; /* = strcpy(utmp.ut_id, "~~"); */
	utmp.ut_line[0] = '~'; utmp.ut_line[1] = '~'; /* = strcpy(utmp.ut_line, "~~"); */
	uname(&uts);
	safe_strncpy(utmp.ut_host, uts.release, sizeof(utmp.ut_host));
	updwtmpx(bb_path_wtmp_file, &utmp);
}
#else
#define write_wtmp() ((void)0)
#endif

#if ENABLE_FEATURE_WAIT_FOR_INIT
/* In Linux, "poweroff" may be spawned even before init.
 * For example, with ACPI:
 * linux/drivers/acpi/bus.c:
 *  static void sb_notify_work(struct work_struct *dummy)
 *      orderly_poweroff(true);
 * linux/kernel/reboot.c:
 *  static int run_cmd(const char *cmd)
 *      ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
 *  poweroff_cmd[] = "/sbin/poweroff";
 *  static int __orderly_poweroff(bool force)
 *      ret = run_cmd(poweroff_cmd);
 *
 * We want to make sure init exists and listens to signals.
 */
static int init_was_not_there(void)
{
	enum { initial = 5 }; /* 5 seconds should be plenty for timeout */
	int cnt = initial - 1;

	/* Just existence of PID 1 does not mean it installed
	 * the handlers already.
	 */
#if 0
	while (kill(1, 0) != 0 && --cnt >= 0)
		sleep(1);
#endif
	/* ... so let's wait for some evidence a usual startup event,
	 * mounting of /proc, happened. By that time init should be ready
	 * for signals.
	 */
	while (access("/proc/meminfo", F_OK) != 0 && --cnt >= 0)
		sleep(1);

	/* Does it look like init wasn't there? */
	return (cnt != initial - 1);
}
#else
  /* Assume it's always there */
# define init_was_not_there() 0
#endif

int halt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int halt_main(int argc UNUSED_PARAM, char **argv)
{
	static const int magic[] = {
		RB_HALT_SYSTEM,
		RB_POWER_OFF,
		RB_AUTOBOOT
	};
	static const smallint signals[] = { SIGUSR1, SIGUSR2, SIGTERM };

	int delay = 0;
	int which, flags, rc;

	/* Figure out which applet we're running */
	if (ENABLE_HALT && !ENABLE_POWEROFF && !ENABLE_REBOOT)
		which = 0;
	else
	if (!ENABLE_HALT && ENABLE_POWEROFF && !ENABLE_REBOOT)
		which = 1;
	else
	if (!ENABLE_HALT && !ENABLE_POWEROFF && ENABLE_REBOOT)
		which = 2;
	else
	for (which = 0; "hpr"[which] != applet_name[0]; which++)
		continue;

	/* Parse and handle arguments */
	/* We support -w even if !ENABLE_FEATURE_WTMP,
	 * in order to not break scripts.
	 * -i (shut down network interfaces) is ignored.
	 */
	flags = getopt32(argv, "d:+nfwi", &delay);

	sleep(delay);

	write_wtmp();

	if (flags & 8) /* -w */
		return EXIT_SUCCESS;

	if (!(flags & 2)) /* no -n */
		sync();

	/* Perform action. */
	rc = 1;
	if (!(flags & 4)) { /* no -f */
//TODO: I tend to think that signalling linuxrc is wrong
// pity original author didn't comment on it...
		if (ENABLE_LINUXRC) {
			/* talk to linuxrc */
			/* bbox init/linuxrc assumed */
			pid_t *pidlist = find_pid_by_name("linuxrc");
			if (pidlist[0] > 0)
				rc = kill(pidlist[0], signals[which]);
			if (ENABLE_FEATURE_CLEAN_UP)
				free(pidlist);
		}
		if (rc) {
			/* talk to init */
			if (!ENABLE_FEATURE_CALL_TELINIT) {
				/* bbox init assumed */
				rc = kill(1, signals[which]);
				if (init_was_not_there())
					rc = kill(1, signals[which]);
			} else {
				/* SysV style init assumed */
				/* runlevels:
				 * 0 == shutdown
				 * 6 == reboot */
				execlp(CONFIG_TELINIT_PATH,
						CONFIG_TELINIT_PATH,
						which == 2 ? "6" : "0",
						(char *)NULL
				);
				bb_perror_msg_and_die("can't execute '%s'",
						CONFIG_TELINIT_PATH);
			}
		}
	} else {
		rc = reboot(magic[which]);
	}

	if (rc)
		bb_perror_nomsg_and_die();
	return rc;
}