/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/

/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <assert.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>

#ifdef HAVE_AUDIT
#include <libaudit.h>
#endif

#include "sd-bus.h"

#include "log.h"
#include "macro.h"
#include "util.h"
#include "special.h"
#include "utmp-wtmp.h"
#include "bus-util.h"
#include "bus-error.h"

typedef struct Context {
        sd_bus *bus;
#ifdef HAVE_AUDIT
        int audit_fd;
#endif
} Context;

static usec_t get_startup_time(Context *c) {
        usec_t t = 0;
        _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
        int r;

        assert(c);

        r = sd_bus_call_method(
                        c->bus,
                        "org.freedesktop.systemd1",
                        "/org/freedesktop/systemd1",
                        "org.freedesktop.DBus.Properties",
                        "Get",
                        &error,
                        &reply,
                        "ss",
                        "org.freedesktop.systemd1.Manager",
                        "UserspaceTimestamp");
        if (r < 0) {
                log_error("Failed to get timestamp: %s", bus_error_message(&error, -r));
                return t;
        }

        r = sd_bus_message_read(reply, "v", "t", &t);
        if (r < 0)
                return bus_log_parse_error(r);

        return t;
}

static int get_current_runlevel(Context *c) {
        static const struct {
                const int runlevel;
                const char *special;
        } table[] = {
                /* The first target of this list that is active or has
                 * a job scheduled wins. We prefer runlevels 5 and 3
                 * here over the others, since these are the main
                 * runlevels used on Fedora. It might make sense to
                 * change the order on some distributions. */
                { '5', SPECIAL_RUNLEVEL5_TARGET },
                { '3', SPECIAL_RUNLEVEL3_TARGET },
                { '4', SPECIAL_RUNLEVEL4_TARGET },
                { '2', SPECIAL_RUNLEVEL2_TARGET },
                { '1', SPECIAL_RESCUE_TARGET },
        };

        _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
        int r;
        unsigned i;

        assert(c);

        for (i = 0; i < ELEMENTSOF(table); i++) {
                _cleanup_bus_message_unref_ sd_bus_message *reply1 = NULL, *reply2 = NULL;
                const char *path = NULL, *state;

                r = sd_bus_call_method(
                                c->bus,
                                "org.freedesktop.systemd1",
                                "/org/freedesktop/systemd1",
                                "org.freedesktop.systemd1.Manager",
                                "LoadUnit",
                                &error,
                                &reply1,
                                "s", table[i].special);
                if (r < 0) {
                        log_error("Failed to get runlevel: %s", bus_error_message(&error, -r));
                        if (r == -ENOMEM)
                                return r;
                        else
                                continue;
                }

                r = sd_bus_message_read(reply1, "o", &path);
                if (r < 0)
                        return bus_log_parse_error(r);

                r = sd_bus_call_method(
                                c->bus,
                                "org.freedesktop.systemd1",
                                path,
                                "org.freedesktop.DBus.Properties",
                                "Get",
                                &error,
                                &reply2,
                                "ss", "org.freedesktop.systemd1.Unit", "ActiveState");
                if (r < 0) {
                        log_error("Failed to get state: %s", bus_error_message(&error, -r));
                        return r;
                }

                r = sd_bus_message_read(reply2, "v", "s", &state);
                if (r < 0)
                        return bus_log_parse_error(r);

                if (streq(state, "active") || streq(state, "reloading"))
                        return table[i].runlevel;
        }

        return 0;
}

static int on_reboot(Context *c) {
        int r = 0, q;
        usec_t t;

        assert(c);

        /* We finished start-up, so let's write the utmp
         * record and send the audit msg */

#ifdef HAVE_AUDIT
        if (c->audit_fd >= 0)
                if (audit_log_user_message(c->audit_fd, AUDIT_SYSTEM_BOOT, "init", NULL, NULL, NULL, 1) < 0 &&
                    errno != EPERM) {
                        log_error("Failed to send audit message: %m");
                        r = -errno;
                }
#endif

        /* If this call fails it will return 0, which
         * utmp_put_reboot() will then fix to the current time */
        t = get_startup_time(c);

        if ((q = utmp_put_reboot(t)) < 0) {
                log_error("Failed to write utmp record: %s", strerror(-q));
                r = q;
        }

        return r;
}

static int on_shutdown(Context *c) {
        int r = 0, q;

        assert(c);

        /* We started shut-down, so let's write the utmp
         * record and send the audit msg */

#ifdef HAVE_AUDIT
        if (c->audit_fd >= 0)
                if (audit_log_user_message(c->audit_fd, AUDIT_SYSTEM_SHUTDOWN, "init", NULL, NULL, NULL, 1) < 0 &&
                    errno != EPERM) {
                        log_error("Failed to send audit message: %m");
                        r = -errno;
                }
#endif

        if ((q = utmp_put_shutdown()) < 0) {
                log_error("Failed to write utmp record: %s", strerror(-q));
                r = q;
        }

        return r;
}

static int on_runlevel(Context *c) {
        int r = 0, q, previous, runlevel;

        assert(c);

        /* We finished changing runlevel, so let's write the
         * utmp record and send the audit msg */

        /* First, get last runlevel */
        if ((q = utmp_get_runlevel(&previous, NULL)) < 0) {

                if (q != -ESRCH && q != -ENOENT) {
                        log_error("Failed to get current runlevel: %s", strerror(-q));
                        return q;
                }

                /* Hmm, we didn't find any runlevel, that means we
                 * have been rebooted */
                r = on_reboot(c);
                previous = 0;
        }

        /* Secondly, get new runlevel */
        if ((runlevel = get_current_runlevel(c)) < 0)
                return runlevel;

        if (previous == runlevel)
                return 0;

#ifdef HAVE_AUDIT
        if (c->audit_fd >= 0) {
                char *s = NULL;

                if (asprintf(&s, "old-level=%c new-level=%c",
                             previous > 0 ? previous : 'N',
                             runlevel > 0 ? runlevel : 'N') < 0)
                        return -ENOMEM;

                if (audit_log_user_message(c->audit_fd, AUDIT_SYSTEM_RUNLEVEL, s, NULL, NULL, NULL, 1) < 0 &&
                    errno != EPERM) {
                        log_error("Failed to send audit message: %m");
                        r = -errno;
                }

                free(s);
        }
#endif

        if ((q = utmp_put_runlevel(runlevel, previous)) < 0) {
                if (q != -ESRCH && q != -ENOENT) {
                        log_error("Failed to write utmp record: %s", strerror(-q));
                        r = q;
                }
        }

        return r;
}

int main(int argc, char *argv[]) {
        int r;
        Context c = {};

#ifdef HAVE_AUDIT
        c.audit_fd = -1;
#endif

        if (getppid() != 1) {
                log_error("This program should be invoked by init only.");
                return EXIT_FAILURE;
        }

        if (argc != 2) {
                log_error("This program requires one argument.");
                return EXIT_FAILURE;
        }

        log_set_target(LOG_TARGET_AUTO);
        log_parse_environment();
        log_open();

        umask(0022);

#ifdef HAVE_AUDIT
        if ((c.audit_fd = audit_open()) < 0 &&
            /* If the kernel lacks netlink or audit support,
             * don't worry about it. */
            errno != EAFNOSUPPORT && errno != EPROTONOSUPPORT)
                log_error("Failed to connect to audit log: %m");
#endif
        r = bus_open_system_systemd(&c.bus);
        if (r < 0) {
                log_error("Failed to get D-Bus connection: %s", strerror(-r));
                r = -EIO;
                goto finish;
        }

        log_debug("systemd-update-utmp running as pid %lu", (unsigned long) getpid());

        if (streq(argv[1], "reboot"))
                r = on_reboot(&c);
        else if (streq(argv[1], "shutdown"))
                r = on_shutdown(&c);
        else if (streq(argv[1], "runlevel"))
                r = on_runlevel(&c);
        else {
                log_error("Unknown command %s", argv[1]);
                r = -EINVAL;
        }

        log_debug("systemd-update-utmp stopped as pid %lu", (unsigned long) getpid());

finish:
#ifdef HAVE_AUDIT
        if (c.audit_fd >= 0)
                audit_close(c.audit_fd);
#endif

        if (c.bus)
                sd_bus_unref(c.bus);

        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}