/* 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;
}