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

/***
  This file is part of systemd.

  Copyright 2011 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 <errno.h>
#include <string.h>
#include <unistd.h>

#include "sd-id128.h"
#include "sd-messages.h"
#include "sd-event.h"
#include "sd-bus.h"

#include "util.h"
#include "strv.h"
#include "def.h"
#include "clock-util.h"
#include "conf-files.h"
#include "path-util.h"
#include "fileio-label.h"
#include "label.h"
#include "bus-util.h"
#include "event-util.h"

#define NULL_ADJTIME_UTC "0.0 0 0\n0\nUTC\n"
#define NULL_ADJTIME_LOCAL "0.0 0 0\n0\nLOCAL\n"

typedef struct Context {
        char *zone;
        bool local_rtc;
        unsigned can_ntp;
        unsigned use_ntp;
        Hashmap *polkit_registry;
} Context;

static void context_reset(Context *c) {
        assert(c);

        free(c->zone);
        c->zone = NULL;

        c->local_rtc = false;
        c->can_ntp = c->use_ntp = -1;
}

static void context_free(Context *c, sd_bus *bus) {
        assert(c);

        context_reset(c);
        bus_verify_polkit_async_registry_free(bus, c->polkit_registry);
}

static bool valid_timezone(const char *name) {
        const char *p;
        char *t;
        bool slash = false;
        int r;
        struct stat st;

        assert(name);

        if (*name == '/' || *name == 0)
                return false;

        for (p = name; *p; p++) {
                if (!(*p >= '0' && *p <= '9') &&
                    !(*p >= 'a' && *p <= 'z') &&
                    !(*p >= 'A' && *p <= 'Z') &&
                    !(*p == '-' || *p == '_' || *p == '+' || *p == '/'))
                        return false;

                if (*p == '/') {

                        if (slash)
                                return false;

                        slash = true;
                } else
                        slash = false;
        }

        if (slash)
                return false;

        t = strappend("/usr/share/zoneinfo/", name);
        if (!t)
                return false;

        r = stat(t, &st);
        free(t);

        if (r < 0)
                return false;

        if (!S_ISREG(st.st_mode))
                return false;

        return true;
}

static int context_read_data(Context *c) {
        _cleanup_free_ char *t = NULL;
        int r;

        assert(c);

        context_reset(c);

        r = readlink_malloc("/etc/localtime", &t);
        if (r < 0) {
                if (r == -EINVAL)
                        log_warning("/etc/localtime should be a symbolic link to a time zone data file in /usr/share/zoneinfo/.");
                else
                        log_warning("Failed to get target of /etc/localtime: %s", strerror(-r));
        } else {
                const char *e;

                e = path_startswith(t, "/usr/share/zoneinfo/");
                if (!e)
                        e = path_startswith(t, "../usr/share/zoneinfo/");

                if (!e)
                        log_warning("/etc/localtime should be a symbolic link to a time zone data file in /usr/share/zoneinfo/.");
                else {
                        c->zone = strdup(e);
                        if (!c->zone)
                                return log_oom();

                        goto have_timezone;
                }
        }

have_timezone:
        if (isempty(c->zone)) {
                free(c->zone);
                c->zone = NULL;
        }

        c->local_rtc = clock_is_localtime() > 0;

        return 0;
}

static int context_write_data_timezone(Context *c) {
        _cleanup_free_ char *p = NULL;
        int r = 0;

        assert(c);

        if (isempty(c->zone)) {
                if (unlink("/etc/localtime") < 0 && errno != ENOENT)
                        r = -errno;

                return r;
        }

        p = strappend("../usr/share/zoneinfo/", c->zone);
        if (!p)
                return log_oom();

        r = symlink_atomic(p, "/etc/localtime");
        if (r < 0)
                return r;

        return 0;
}

static int context_write_data_local_rtc(Context *c) {
        int r;
        _cleanup_free_ char *s = NULL, *w = NULL;

        assert(c);

        r = read_full_file("/etc/adjtime", &s, NULL);
        if (r < 0) {
                if (r != -ENOENT)
                        return r;

                if (!c->local_rtc)
                        return 0;

                w = strdup(NULL_ADJTIME_LOCAL);
                if (!w)
                        return -ENOMEM;
        } else {
                char *p, *e;
                size_t a, b;

                p = strchr(s, '\n');
                if (!p)
                        return -EIO;

                p = strchr(p+1, '\n');
                if (!p)
                        return -EIO;

                p++;
                e = strchr(p, '\n');
                if (!e)
                        return -EIO;

                a = p - s;
                b = strlen(e);

                w = new(char, a + (c->local_rtc ? 5 : 3) + b + 1);
                if (!w)
                        return -ENOMEM;

                *(char*) mempcpy(stpcpy(mempcpy(w, s, a), c->local_rtc ? "LOCAL" : "UTC"), e, b) = 0;

                if (streq(w, NULL_ADJTIME_UTC)) {
                        if (unlink("/etc/adjtime") < 0)
                                if (errno != ENOENT)
                                        return -errno;

                        return 0;
                }
        }

        label_init("/etc");
        return write_string_file_atomic_label("/etc/adjtime", w);
}

static char** get_ntp_services(void) {
        _cleanup_strv_free_ char **r = NULL, **files = NULL;
        char **i;
        int k;

        k = conf_files_list(&files, ".list", NULL,
                            "/etc/systemd/ntp-units.d",
                            "/run/systemd/ntp-units.d",
                            "/usr/local/lib/systemd/ntp-units.d",
                            "/usr/lib/systemd/ntp-units.d",
                            NULL);
        if (k < 0)
                return NULL;

        STRV_FOREACH(i, files) {
                _cleanup_fclose_ FILE *f;

                f = fopen(*i, "re");
                if (!f)
                        continue;

                for (;;) {
                        char line[PATH_MAX], *l;

                        if (!fgets(line, sizeof(line), f)) {
                                if (ferror(f))
                                        log_error("Failed to read NTP unit file: %m");

                                break;
                        }

                        l = strstrip(line);
                        if (l[0] == 0 || l[0] == '#')
                                continue;

                        if (strv_extend(&r, l) < 0) {
                                log_oom();
                                return NULL;
                        }
                }
        }

        i = r;
        r = NULL; /* avoid cleanup */

        return strv_uniq(i);
}

static int context_read_ntp(Context *c, sd_bus *bus) {
        _cleanup_strv_free_ char **l;
        char **i;
        int r;

        assert(c);
        assert(bus);

        l = get_ntp_services();
        STRV_FOREACH(i, l) {
                _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_NULL;
                sd_bus_message *reply = NULL;
                const char *s;

                r = sd_bus_call_method(
                                bus,
                                "org.freedesktop.systemd1",
                                "/org/freedesktop/systemd1",
                                "org.freedesktop.systemd1.Manager",
                                "GetUnitFileState",
                                &error,
                                &reply,
                                "s",
                                *i);

                if (r < 0) {
                        /* This implementation does not exist. Try the next one. */
                        if (sd_bus_error_has_name(&error, SD_BUS_ERROR_FILE_NOT_FOUND))
                                continue;

                        return r;
                }

                r = sd_bus_message_read(reply, "s", &s);
                if (r < 0)
                        return r;

                c->can_ntp = 1;
                c->use_ntp =
                        streq(s, "enabled") ||
                        streq(s, "enabled-runtime");

                return 0;
        }

        /* NTP is not installed. */
        c->can_ntp = 0;
        c->use_ntp = 0;

        return 0;
}

static int context_start_ntp(Context *c, sd_bus *bus, sd_bus_error *error) {
        _cleanup_strv_free_ char **l = NULL;
        char **i;
        int r;

        assert(c);
        assert(bus);
        assert(error);

        l = get_ntp_services();
        STRV_FOREACH(i, l) {

                if (c->use_ntp)
                        r = sd_bus_call_method(
                                        bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
                                        "org.freedesktop.systemd1.Manager",
                                        "StartUnit",
                                        error,
                                        NULL,
                                        "ss", *i, "replace");
                else
                        r = sd_bus_call_method(
                                        bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
                                        "org.freedesktop.systemd1.Manager",
                                        "StopUnit",
                                        error,
                                        NULL,
                                        "ss", *i, "replace");

                if (r < 0) {
                        if (sd_bus_error_has_name(error, SD_BUS_ERROR_FILE_NOT_FOUND) ||
                            sd_bus_error_has_name(error, "org.freedesktop.systemd1.LoadFailed") ||
                            sd_bus_error_has_name(error, "org.freedesktop.systemd1.NoSuchUnit")) {
                                /* This implementation does not exist. Try the next one. */
                                sd_bus_error_free(error);
                                continue;
                        }

                        return r;
                }

                return 1;
        }

        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
        return -ENOTSUP;
}

static int context_enable_ntp(Context*c, sd_bus *bus, sd_bus_error *error) {
        _cleanup_strv_free_ char **l = NULL;
        char **i;
        int r;

        assert(c);
        assert(bus);
        assert(error);

        l = get_ntp_services();
        STRV_FOREACH(i, l) {
                if (c->use_ntp)
                        r = sd_bus_call_method(
                                        bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
                                        "org.freedesktop.systemd1.Manager",
                                        "EnableUnitFiles",
                                        error,
                                        NULL,
                                        "asbb", 1, *i, false, true);
                else
                        r = sd_bus_call_method(
                                        bus,
                                        "org.freedesktop.systemd1",
                                        "/org/freedesktop/systemd1",
                                        "org.freedesktop.systemd1.Manager",
                                        "DisableUnitFiles",
                                        error,
                                        NULL,
                                        "asb", 1, *i, false);

                if (r < 0) {
                        if (sd_bus_error_has_name(error, SD_BUS_ERROR_FILE_NOT_FOUND)) {
                                /* This implementation does not exist. Try the next one. */
                                sd_bus_error_free(error);
                                continue;
                        }

                        return r;
                }

                r = sd_bus_call_method(
                                bus,
                                "org.freedesktop.systemd1",
                                "/org/freedesktop/systemd1",
                                "org.freedesktop.systemd1.Manager",
                                "Reload",
                                error,
                                NULL,
                                NULL);
                if (r < 0)
                        return r;

                return 1;
        }

        sd_bus_error_set_const(error, "org.freedesktop.timedate1.NoNTPSupport", "NTP not supported.");
        return -ENOTSUP;
}

static int property_get_rtc_time(
                sd_bus *bus,
                const char *path,
                const char *interface,
                const char *property,
                sd_bus_message *reply,
                void *userdata,
                sd_bus_error *error) {

        struct tm tm;
        usec_t t;
        int r;

        zero(tm);
        r = clock_get_hwclock(&tm);
        if (r == -EBUSY) {
                log_warning("/dev/rtc is busy. Is somebody keeping it open continuously? That's not a good idea... Returning a bogus RTC timestamp.");
                t = 0;
        } else if (r == -ENOENT) {
                log_debug("/dev/rtc not found.");
                t = 0; /* no RTC found */
        } else if (r < 0)
                return sd_bus_error_set_errnof(error, r, "Failed to read RTC: %s", strerror(-r));
        else
                t = (usec_t) timegm(&tm) * USEC_PER_SEC;

        return sd_bus_message_append(reply, "t", t);
}

static int property_get_time(
                sd_bus *bus,
                const char *path,
                const char *interface,
                const char *property,
                sd_bus_message *reply,
                void *userdata,
                sd_bus_error *error) {

        return sd_bus_message_append(reply, "t", now(CLOCK_REALTIME));
}

static int property_get_ntp_sync(
                sd_bus *bus,
                const char *path,
                const char *interface,
                const char *property,
                sd_bus_message *reply,
                void *userdata,
                sd_bus_error *error) {

        return sd_bus_message_append(reply, "b", ntp_synced());
}

static int method_set_timezone(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
        Context *c = userdata;
        const char *z;
        int interactive;
        char *t;
        int r;

        assert(bus);
        assert(m);
        assert(c);

        r = sd_bus_message_read(m, "sb", &z, &interactive);
        if (r < 0)
                return r;

        if (!valid_timezone(z))
                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid time zone '%s'", z);

        if (streq_ptr(z, c->zone))
                return sd_bus_reply_method_return(m, NULL);

        r = bus_verify_polkit_async(bus, &c->polkit_registry, m, "org.freedesktop.timedate1.set-timezone", interactive, error, method_set_timezone, c);
        if (r < 0)
                return r;
        if (r == 0)
                return 1; /* No authorization for now, but the async polkit stuff will call us again when it has it */

        t = strdup(z);
        if (!t)
                return -ENOMEM;

        free(c->zone);
        c->zone = t;

        /* 1. Write new configuration file */
        r = context_write_data_timezone(c);
        if (r < 0) {
                log_error("Failed to set time zone: %s", strerror(-r));
                return sd_bus_error_set_errnof(error, r, "Failed to set time zone: %s", strerror(-r));
        }

        /* 2. Tell the kernel our timezone */
        clock_set_timezone(NULL);

        if (c->local_rtc) {
                struct timespec ts;
                struct tm *tm;

                /* 3. Sync RTC from system clock, with the new delta */
                assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);
                assert_se(tm = localtime(&ts.tv_sec));
                clock_set_hwclock(tm);
        }

        log_struct(LOG_INFO,
                   MESSAGE_ID(SD_MESSAGE_TIMEZONE_CHANGE),
                   "TIMEZONE=%s", c->zone,
                   "MESSAGE=Changed time zone to '%s'.", c->zone,
                   NULL);

        sd_bus_emit_properties_changed(bus, "/org/freedesktop/timedate1", "org.freedesktop.timedate1", "Timezone", NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int method_set_local_rtc(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
        int lrtc, fix_system, interactive;
        Context *c = userdata;
        struct timespec ts;
        int r;

        assert(bus);
        assert(m);
        assert(c);

        r = sd_bus_message_read(m, "bbb", &lrtc, &fix_system, &interactive);
        if (r < 0)
                return r;

        if (lrtc == c->local_rtc)
                return sd_bus_reply_method_return(m, NULL);

        r = bus_verify_polkit_async(bus, &c->polkit_registry, m, "org.freedesktop.timedate1.set-local-rtc", interactive, error, method_set_local_rtc, c);
        if (r < 0)
                return r;
        if (r == 0)
                return 1;

        c->local_rtc = lrtc;

        /* 1. Write new configuration file */
        r = context_write_data_local_rtc(c);
        if (r < 0) {
                log_error("Failed to set RTC to local/UTC: %s", strerror(-r));
                return sd_bus_error_set_errnof(error, r, "Failed to set RTC to local/UTC: %s", strerror(-r));
        }

        /* 2. Tell the kernel our timezone */
        clock_set_timezone(NULL);

        /* 3. Synchronize clocks */
        assert_se(clock_gettime(CLOCK_REALTIME, &ts) == 0);

        if (fix_system) {
                struct tm tm;

                /* Sync system clock from RTC; first,
                 * initialize the timezone fields of
                 * struct tm. */
                if (c->local_rtc)
                        tm = *localtime(&ts.tv_sec);
                else
                        tm = *gmtime(&ts.tv_sec);

                /* Override the main fields of
                 * struct tm, but not the timezone
                 * fields */
                if (clock_get_hwclock(&tm) >= 0) {

                        /* And set the system clock
                         * with this */
                        if (c->local_rtc)
                                ts.tv_sec = mktime(&tm);
                        else
                                ts.tv_sec = timegm(&tm);

                        clock_settime(CLOCK_REALTIME, &ts);
                }

        } else {
                struct tm *tm;

                /* Sync RTC from system clock */
                if (c->local_rtc)
                        tm = localtime(&ts.tv_sec);
                else
                        tm = gmtime(&ts.tv_sec);

                clock_set_hwclock(tm);
        }

        log_info("RTC configured to %s time.", c->local_rtc ? "local" : "UTC");

        sd_bus_emit_properties_changed(bus, "/org/freedesktop/timedate1", "org.freedesktop.timedate1", "LocalRTC", NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int method_set_time(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
        int relative, interactive;
        Context *c = userdata;
        int64_t utc;
        struct timespec ts;
        struct tm* tm;
        int r;

        assert(bus);
        assert(m);
        assert(c);

        r = sd_bus_message_read(m, "xbb", &utc, &relative, &interactive);
        if (r < 0)
                return r;

        if (!relative && utc <= 0)
                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid absolute time");

        if (relative && utc == 0)
                return sd_bus_reply_method_return(m, NULL);

        if (relative) {
                usec_t n, x;

                n = now(CLOCK_REALTIME);
                x = n + utc;

                if ((utc > 0 && x < n) ||
                    (utc < 0 && x > n))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Time value overflow");

                timespec_store(&ts, x);
        } else
                timespec_store(&ts, (usec_t) utc);

        r = bus_verify_polkit_async(bus, &c->polkit_registry, m, "org.freedesktop.timedate1.set-time", interactive, error, method_set_time, c);
        if (r < 0)
                return r;
        if (r == 0)
                return 1;

        /* Set system clock */
        if (clock_settime(CLOCK_REALTIME, &ts) < 0) {
                log_error("Failed to set local time: %m");
                return sd_bus_error_set_errnof(error, errno, "Failed to set local time: %m");
        }

        /* Sync down to RTC */
        if (c->local_rtc)
                tm = localtime(&ts.tv_sec);
        else
                tm = gmtime(&ts.tv_sec);
        clock_set_hwclock(tm);

        log_struct(LOG_INFO,
                   MESSAGE_ID(SD_MESSAGE_TIME_CHANGE),
                   "REALTIME="USEC_FMT, timespec_load(&ts),
                   "MESSAGE=Changed local time to %s", ctime(&ts.tv_sec),
                   NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int method_set_ntp(sd_bus *bus, sd_bus_message *m, void *userdata, sd_bus_error *error) {
        int ntp, interactive;
        Context *c = userdata;
        int r;

        r = sd_bus_message_read(m, "bb", &ntp, &interactive);
        if (r < 0)
                return r;

        if ((bool)ntp == c->use_ntp)
                return sd_bus_reply_method_return(m, NULL);

        r = bus_verify_polkit_async(bus, &c->polkit_registry, m, "org.freedesktop.timedate1.set-ntp", interactive, error, method_set_ntp, c);
        if (r < 0)
                return r;
        if (r == 0)
                return 1;

        c->use_ntp = ntp;

        r = context_enable_ntp(c, bus, error);
        if (r < 0)
                return r;

        r = context_start_ntp(c, bus, error);
        if (r < 0)
                return r;

        log_info("Set NTP to %s", c->use_ntp ? "enabled" : "disabled");

        sd_bus_emit_properties_changed(bus, "/org/freedesktop/timedate1", "org.freedesktop.timedate1", "NTP", NULL);

        return sd_bus_reply_method_return(m, NULL);
}

#include <sys/capability.h>

static const sd_bus_vtable timedate_vtable[] = {
        SD_BUS_VTABLE_START(0),
        SD_BUS_PROPERTY("Timezone", "s", NULL, offsetof(Context, zone), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("LocalRTC", "b", NULL, offsetof(Context, local_rtc), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("CanNTP", "b", bus_property_get_tristate, offsetof(Context, can_ntp), 0),
        SD_BUS_PROPERTY("NTP", "b", bus_property_get_tristate, offsetof(Context, use_ntp), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("NTPSynchronized", "b", property_get_ntp_sync, 0, 0),
        SD_BUS_PROPERTY("TimeUSec", "t", property_get_time, 0, 0),
        SD_BUS_PROPERTY("RTCTimeUSec", "t", property_get_rtc_time, 0, 0),
        SD_BUS_METHOD("SetTime", "xbb", NULL, method_set_time, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetTimezone", "sb", NULL, method_set_timezone, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetLocalRTC", "bbb", NULL, method_set_local_rtc, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetNTP", "bb", NULL, method_set_ntp, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_VTABLE_END,
};

static int connect_bus(Context *c, sd_event *event, sd_bus **_bus) {
        _cleanup_bus_unref_ sd_bus *bus = NULL;
        int r;

        assert(c);
        assert(event);
        assert(_bus);

        r = sd_bus_default_system(&bus);
        if (r < 0) {
                log_error("Failed to get system bus connection: %s", strerror(-r));
                return r;
        }

        r = sd_bus_add_object_vtable(bus, NULL, "/org/freedesktop/timedate1", "org.freedesktop.timedate1", timedate_vtable, c);
        if (r < 0) {
                log_error("Failed to register object: %s", strerror(-r));
                return r;
        }

        r = sd_bus_request_name(bus, "org.freedesktop.timedate1", 0);
        if (r < 0) {
                log_error("Failed to register name: %s", strerror(-r));
                return r;
        }

        r = sd_bus_attach_event(bus, event, 0);
        if (r < 0) {
                log_error("Failed to attach bus to event loop: %s", strerror(-r));
                return r;
        }

        *_bus = bus;
        bus = NULL;

        return 0;
}

int main(int argc, char *argv[]) {
        Context context = {
                .zone = NULL,
                .local_rtc = false,
                .can_ntp = -1,
                .use_ntp = -1,
        };

        _cleanup_event_unref_ sd_event *event = NULL;
        _cleanup_bus_unref_ sd_bus *bus = NULL;
        int r;

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

        umask(0022);

        if (argc != 1) {
                log_error("This program takes no arguments.");
                r = -EINVAL;
                goto finish;
        }

        r = sd_event_default(&event);
        if (r < 0) {
                log_error("Failed to allocate event loop: %s", strerror(-r));
                goto finish;
        }

        sd_event_set_watchdog(event, true);

        r = connect_bus(&context, event, &bus);
        if (r < 0)
                goto finish;

        r = context_read_data(&context);
        if (r < 0) {
                log_error("Failed to read time zone data: %s", strerror(-r));
                goto finish;
        }

        r = context_read_ntp(&context, bus);
        if (r < 0) {
                log_error("Failed to determine whether NTP is enabled: %s", strerror(-r));
                goto finish;
        }

        r = bus_event_loop_with_idle(event, bus, "org.freedesktop.timedate1", DEFAULT_EXIT_USEC, NULL, NULL);
        if (r < 0) {
                log_error("Failed to run event loop: %s", strerror(-r));
                goto finish;
        }

finish:
        context_free(&context, bus);

        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
}