/*-*- 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 General Public License as published by
  the Free Software Foundation; either version 2 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
  General Public License for more details.

  You should have received a copy of the GNU 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>

#include <dbus/dbus.h>

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

#include "log.h"
#include "macro.h"
#include "util.h"
#include "special.h"
#include "utmp-wtmp.h"
#include "dbus-common.h"

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

static usec_t get_startup_time(Context *c) {
        const char
                *interface = "org.freedesktop.systemd1.Manager",
                *property = "StartupTimestamp";

        DBusError error;
        usec_t t = 0;
        DBusMessage *m = NULL, *reply = NULL;
        DBusMessageIter iter, sub;

        dbus_error_init(&error);

        assert(c);

        if (!(m = dbus_message_new_method_call(
                              "org.freedesktop.systemd1",
                              "/org/freedesktop/systemd1",
                              "org.freedesktop.DBus.Properties",
                              "Get"))) {
                log_error("Could not allocate message.");
                goto finish;
        }

        if (!dbus_message_append_args(m,
                                      DBUS_TYPE_STRING, &interface,
                                      DBUS_TYPE_STRING, &property,
                                      DBUS_TYPE_INVALID)) {
                log_error("Could not append arguments to message.");
                goto finish;
        }

        if (!(reply = dbus_connection_send_with_reply_and_block(c->bus, m, -1, &error))) {
                log_error("Failed to send command: %s", error.message);
                goto finish;
        }

        if (!dbus_message_iter_init(reply, &iter) ||
            dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT)  {
                log_error("Failed to parse reply.");
                goto finish;
        }

        dbus_message_iter_recurse(&iter, &sub);

        if (dbus_message_iter_get_arg_type(&sub) != DBUS_TYPE_UINT64)  {
                log_error("Failed to parse reply.");
                goto finish;
        }

        dbus_message_iter_get_basic(&sub, &t);

finish:
        if (m)
                dbus_message_unref(m);

        if (reply)
                dbus_message_unref(reply);

        dbus_error_free(&error);

        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 */
                { '5', SPECIAL_RUNLEVEL5_TARGET },
                { '3', SPECIAL_RUNLEVEL3_TARGET },
                { '4', SPECIAL_RUNLEVEL4_TARGET },
                { '2', SPECIAL_RUNLEVEL2_TARGET },
                { 'S', SPECIAL_RESCUE_TARGET },
        };
        const char
                *interface = "org.freedesktop.systemd1.Unit",
                *property = "ActiveState";

        DBusMessage *m = NULL, *reply = NULL;
        int r = 0;
        unsigned i;
        DBusError error;

        assert(c);

        dbus_error_init(&error);

        for (i = 0; i < ELEMENTSOF(table); i++) {
                const char *path = NULL, *state;
                DBusMessageIter iter, sub;

                if (!(m = dbus_message_new_method_call(
                                      "org.freedesktop.systemd1",
                                      "/org/freedesktop/systemd1",
                                      "org.freedesktop.systemd1.Manager",
                                      "GetUnit"))) {
                        log_error("Could not allocate message.");
                        r = -ENOMEM;
                        goto finish;
                }

                if (!dbus_message_append_args(m,
                                              DBUS_TYPE_STRING, &table[i].special,
                                              DBUS_TYPE_INVALID)) {
                        log_error("Could not append arguments to message.");
                        r = -ENOMEM;
                        goto finish;
                }

                if (!(reply = dbus_connection_send_with_reply_and_block(c->bus, m, -1, &error))) {
                        dbus_error_free(&error);
                        continue;
                }

                if (!dbus_message_get_args(reply, &error,
                                           DBUS_TYPE_OBJECT_PATH, &path,
                                           DBUS_TYPE_INVALID)) {
                        log_error("Failed to parse reply: %s", error.message);
                        r = -EIO;
                        goto finish;
                }

                dbus_message_unref(m);
                if (!(m = dbus_message_new_method_call(
                                      "org.freedesktop.systemd1",
                                      path,
                                      "org.freedesktop.DBus.Properties",
                                      "Get"))) {
                        log_error("Could not allocate message.");
                        r = -ENOMEM;
                        goto finish;
                }

                if (!dbus_message_append_args(m,
                                              DBUS_TYPE_STRING, &interface,
                                              DBUS_TYPE_STRING, &property,
                                              DBUS_TYPE_INVALID)) {
                        log_error("Could not append arguments to message.");
                        r = -ENOMEM;
                        goto finish;
                }

                dbus_message_unref(reply);
                if (!(reply = dbus_connection_send_with_reply_and_block(c->bus, m, -1, &error))) {
                        log_error("Failed to send command: %s", error.message);
                        r = -EIO;
                        goto finish;
                }

                if (!dbus_message_iter_init(reply, &iter) ||
                    dbus_message_iter_get_arg_type(&iter) != DBUS_TYPE_VARIANT)  {
                        log_error("Failed to parse reply.");
                        r = -EIO;
                        goto finish;
                }

                dbus_message_iter_recurse(&iter, &sub);

                if (dbus_message_iter_get_arg_type(&sub) != DBUS_TYPE_STRING)  {
                        log_error("Failed to parse reply.");
                        r = -EIO;
                        goto finish;
                }

                dbus_message_iter_get_basic(&sub, &state);

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

                dbus_message_unref(m);
                dbus_message_unref(reply);
                m = reply = NULL;

                if (r)
                        break;
        }

finish:
        if (m)
                dbus_message_unref(m);

        if (reply)
                dbus_message_unref(reply);

        dbus_error_free(&error);

        return r;
}

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) {
                        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) {
                        log_error("Failed to send audit message: %m");
                        r = -errno;
                }
#endif

        if ((q = utmp_put_shutdown(0)) < 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) {
                        log_error("Failed to send audit message: %m");
                        r = -errno;
                }

                free(s);
        }
#endif

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

        return r;
}

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

        dbus_error_init(&error);

        zero(c);
#ifdef HAVE_AUDIT
        c.audit_fd = -1;
#endif

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

        if (argc != 2) {
                log_error("This program requires one argument.");
                return 1;
        }

        log_set_target(LOG_TARGET_SYSLOG_OR_KMSG);
        log_parse_environment();
        log_open();

#ifdef HAVE_AUDIT
        if ((c.audit_fd = audit_open()) < 0)
                log_error("Failed to connect to audit log: %m");
#endif

        if (bus_connect(DBUS_BUS_SYSTEM, &c.bus, NULL, &error) < 0) {
                log_error("Failed to get D-Bus connection: %s", error.message);
                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) {
               dbus_connection_close(c.bus);
               dbus_connection_unref(c.bus);
        }

        dbus_error_free(&error);
        dbus_shutdown();

        return r < 0 ? 1 : 0;
}