[thirdparty/systemd.git] / src / hostname / hostnamed.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#include <errno.h>
#include <string.h>
#include <sys/utsname.h>
#include <unistd.h>

#include "alloc-util.h"
#include "bus-common-errors.h"
#include "bus-util.h"
#include "def.h"
#include "env-file-label.h"
#include "env-file.h"
#include "env-util.h"
#include "fileio-label.h"
#include "fileio.h"
#include "hostname-util.h"
#include "id128-util.h"
#include "main-func.h"
#include "missing_capability.h"
#include "os-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "selinux-util.h"
#include "signal-util.h"
#include "strv.h"
#include "user-util.h"
#include "util.h"
#include "virt.h"

#define VALID_DEPLOYMENT_CHARS (DIGITS LETTERS "-.:")

enum {
        PROP_HOSTNAME,
        PROP_STATIC_HOSTNAME,
        PROP_PRETTY_HOSTNAME,
        PROP_ICON_NAME,
        PROP_CHASSIS,
        PROP_DEPLOYMENT,
        PROP_LOCATION,
        PROP_KERNEL_NAME,
        PROP_KERNEL_RELEASE,
        PROP_KERNEL_VERSION,
        PROP_OS_PRETTY_NAME,
        PROP_OS_CPE_NAME,
        PROP_HOME_URL,
        _PROP_MAX
};

typedef struct Context {
        char *data[_PROP_MAX];
        Hashmap *polkit_registry;
        sd_id128_t uuid;
        bool has_uuid;
} Context;

static void context_reset(Context *c) {
        int p;

        assert(c);

        for (p = 0; p < _PROP_MAX; p++)
                c->data[p] = mfree(c->data[p]);
}

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

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

static int context_read_data(Context *c) {
        int r;
        struct utsname u;

        assert(c);

        context_reset(c);

        assert_se(uname(&u) >= 0);
        c->data[PROP_KERNEL_NAME] = strdup(u.sysname);
        c->data[PROP_KERNEL_RELEASE] = strdup(u.release);
        c->data[PROP_KERNEL_VERSION] = strdup(u.version);
        if (!c->data[PROP_KERNEL_NAME] || !c->data[PROP_KERNEL_RELEASE] ||
            !c->data[PROP_KERNEL_VERSION])
                return -ENOMEM;

        c->data[PROP_HOSTNAME] = gethostname_malloc();
        if (!c->data[PROP_HOSTNAME])
                return -ENOMEM;

        r = read_etc_hostname(NULL, &c->data[PROP_STATIC_HOSTNAME]);
        if (r < 0 && r != -ENOENT)
                return r;

        r = parse_env_file(NULL, "/etc/machine-info",
                           "PRETTY_HOSTNAME", &c->data[PROP_PRETTY_HOSTNAME],
                           "ICON_NAME", &c->data[PROP_ICON_NAME],
                           "CHASSIS", &c->data[PROP_CHASSIS],
                           "DEPLOYMENT", &c->data[PROP_DEPLOYMENT],
                           "LOCATION", &c->data[PROP_LOCATION]);
        if (r < 0 && r != -ENOENT)
                return r;

        r = parse_os_release(NULL,
                             "PRETTY_NAME", &c->data[PROP_OS_PRETTY_NAME],
                             "CPE_NAME", &c->data[PROP_OS_CPE_NAME],
                             "HOME_URL", &c->data[PROP_HOME_URL],
                             NULL);
        if (r < 0 && r != -ENOENT)
                return r;

        r = id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, &c->uuid);
        if (r < 0)
                log_info_errno(r, "Failed to read product UUID, ignoring: %m");
        c->has_uuid = (r >= 0);

        return 0;
}

static bool valid_chassis(const char *chassis) {
        assert(chassis);

        return nulstr_contains(
                        "vm\0"
                        "container\0"
                        "desktop\0"
                        "laptop\0"
                        "convertible\0"
                        "server\0"
                        "tablet\0"
                        "handset\0"
                        "watch\0"
                        "embedded\0",
                        chassis);
}

static bool valid_deployment(const char *deployment) {
        assert(deployment);

        return in_charset(deployment, VALID_DEPLOYMENT_CHARS);
}

static const char* fallback_chassis(void) {
        char *type;
        unsigned t;
        int v, r;

        v = detect_virtualization();
        if (VIRTUALIZATION_IS_VM(v))
                return "vm";
        if (VIRTUALIZATION_IS_CONTAINER(v))
                return "container";

        r = read_one_line_file("/sys/class/dmi/id/chassis_type", &type);
        if (r < 0)
                goto try_acpi;

        r = safe_atou(type, &t);
        free(type);
        if (r < 0)
                goto try_acpi;

        /* We only list the really obvious cases here. The DMI data is unreliable enough, so let's not do any
           additional guesswork on top of that.

           See the SMBIOS Specification 3.0 section 7.4.1 for details about the values listed here:

           https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.0.0.pdf
         */

        switch (t) {

        case 0x3: /* Desktop */
        case 0x4: /* Low Profile Desktop */
        case 0x6: /* Mini Tower */
        case 0x7: /* Tower */
                return "desktop";

        case 0x8: /* Portable */
        case 0x9: /* Laptop */
        case 0xA: /* Notebook */
        case 0xE: /* Sub Notebook */
                return "laptop";

        case 0xB: /* Hand Held */
                return "handset";

        case 0x11: /* Main Server Chassis */
        case 0x1C: /* Blade */
        case 0x1D: /* Blade Enclosure */
                return "server";

        case 0x1E: /* Tablet */
                return "tablet";

        case 0x1F: /* Convertible */
        case 0x20: /* Detachable */
                return "convertible";
        }

try_acpi:
        r = read_one_line_file("/sys/firmware/acpi/pm_profile", &type);
        if (r < 0)
                return NULL;

        r = safe_atou(type, &t);
        free(type);
        if (r < 0)
                return NULL;

        /* We only list the really obvious cases here as the ACPI data is not really super reliable.
         *
         * See the ACPI 5.0 Spec Section 5.2.9.1 for details:
         *
         * http://www.acpi.info/DOWNLOADS/ACPIspec50.pdf
         */

        switch(t) {

        case 1: /* Desktop */
        case 3: /* Workstation */
        case 6: /* Appliance PC */
                return "desktop";

        case 2: /* Mobile */
                return "laptop";

        case 4: /* Enterprise Server */
        case 5: /* SOHO Server */
        case 7: /* Performance Server */
                return "server";

        case 8: /* Tablet */
                return "tablet";
        }

        return NULL;
}

static char* context_fallback_icon_name(Context *c) {
        const char *chassis;

        assert(c);

        if (!isempty(c->data[PROP_CHASSIS]))
                return strappend("computer-", c->data[PROP_CHASSIS]);

        chassis = fallback_chassis();
        if (chassis)
                return strappend("computer-", chassis);

        return strdup("computer");
}

static bool hostname_is_useful(const char *hn) {
        return !isempty(hn) && !is_localhost(hn);
}

static int context_update_kernel_hostname(Context *c) {
        const char *static_hn;
        const char *hn;

        assert(c);

        static_hn = c->data[PROP_STATIC_HOSTNAME];

        /* /etc/hostname with something other than "localhost"
         * has the highest preference ... */
        if (hostname_is_useful(static_hn))
                hn = static_hn;

        /* ... the transient host name, (ie: DHCP) comes next ... */
        else if (!isempty(c->data[PROP_HOSTNAME]))
                hn = c->data[PROP_HOSTNAME];

        /* ... fallback to static "localhost.*" ignored above ... */
        else if (!isempty(static_hn))
                hn = static_hn;

        /* ... and the ultimate fallback */
        else
                hn = FALLBACK_HOSTNAME;

        if (sethostname_idempotent(hn) < 0)
                return -errno;

        return 0;
}

static int context_write_data_static_hostname(Context *c) {

        assert(c);

        if (isempty(c->data[PROP_STATIC_HOSTNAME])) {

                if (unlink("/etc/hostname") < 0)
                        return errno == ENOENT ? 0 : -errno;

                return 0;
        }
        return write_string_file_atomic_label("/etc/hostname", c->data[PROP_STATIC_HOSTNAME]);
}

static int context_write_data_machine_info(Context *c) {

        static const char * const name[_PROP_MAX] = {
                [PROP_PRETTY_HOSTNAME] = "PRETTY_HOSTNAME",
                [PROP_ICON_NAME] = "ICON_NAME",
                [PROP_CHASSIS] = "CHASSIS",
                [PROP_DEPLOYMENT] = "DEPLOYMENT",
                [PROP_LOCATION] = "LOCATION",
        };

        _cleanup_strv_free_ char **l = NULL;
        int r, p;

        assert(c);

        r = load_env_file(NULL, "/etc/machine-info", &l);
        if (r < 0 && r != -ENOENT)
                return r;

        for (p = PROP_PRETTY_HOSTNAME; p <= PROP_LOCATION; p++) {
                _cleanup_free_ char *t = NULL;
                char **u;

                assert(name[p]);

                if (isempty(c->data[p]))  {
                        strv_env_unset(l, name[p]);
                        continue;
                }

                t = strjoin(name[p], "=", c->data[p]);
                if (!t)
                        return -ENOMEM;

                u = strv_env_set(l, t);
                if (!u)
                        return -ENOMEM;

                strv_free_and_replace(l, u);
        }

        if (strv_isempty(l)) {
                if (unlink("/etc/machine-info") < 0)
                        return errno == ENOENT ? 0 : -errno;

                return 0;
        }

        return write_env_file_label("/etc/machine-info", l);
}

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

        _cleanup_free_ char *n = NULL;
        Context *c = userdata;
        const char *name;

        if (isempty(c->data[PROP_ICON_NAME]))
                name = n = context_fallback_icon_name(c);
        else
                name = c->data[PROP_ICON_NAME];

        if (!name)
                return -ENOMEM;

        return sd_bus_message_append(reply, "s", name);
}

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

        Context *c = userdata;
        const char *name;

        if (isempty(c->data[PROP_CHASSIS]))
                name = fallback_chassis();
        else
                name = c->data[PROP_CHASSIS];

        return sd_bus_message_append(reply, "s", name);
}

static int method_set_hostname(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        Context *c = userdata;
        const char *name;
        int interactive;
        int r;

        assert(m);
        assert(c);

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

        if (isempty(name))
                name = c->data[PROP_STATIC_HOSTNAME];

        if (isempty(name))
                name = FALLBACK_HOSTNAME;

        if (!hostname_is_valid(name, false))
                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid hostname '%s'", name);

        if (streq_ptr(name, c->data[PROP_HOSTNAME]))
                return sd_bus_reply_method_return(m, NULL);

        r = bus_verify_polkit_async(
                        m,
                        CAP_SYS_ADMIN,
                        "org.freedesktop.hostname1.set-hostname",
                        NULL,
                        interactive,
                        UID_INVALID,
                        &c->polkit_registry,
                        error);
        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 */

        r = free_and_strdup(&c->data[PROP_HOSTNAME], name);
        if (r < 0)
                return r;

        r = context_update_kernel_hostname(c);
        if (r < 0) {
                log_error_errno(r, "Failed to set host name: %m");
                return sd_bus_error_set_errnof(error, r, "Failed to set hostname: %m");
        }

        log_info("Changed host name to '%s'", strna(c->data[PROP_HOSTNAME]));

        (void) sd_bus_emit_properties_changed(sd_bus_message_get_bus(m), "/org/freedesktop/hostname1", "org.freedesktop.hostname1", "Hostname", NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int method_set_static_hostname(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        Context *c = userdata;
        const char *name;
        int interactive;
        int r;

        assert(m);
        assert(c);

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

        name = empty_to_null(name);

        if (streq_ptr(name, c->data[PROP_STATIC_HOSTNAME]))
                return sd_bus_reply_method_return(m, NULL);

        if (!isempty(name) && !hostname_is_valid(name, false))
                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid static hostname '%s'", name);

        r = bus_verify_polkit_async(
                        m,
                        CAP_SYS_ADMIN,
                        "org.freedesktop.hostname1.set-static-hostname",
                        NULL,
                        interactive,
                        UID_INVALID,
                        &c->polkit_registry,
                        error);
        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 */

        r = free_and_strdup(&c->data[PROP_STATIC_HOSTNAME], name);
        if (r < 0)
                return r;

        r = context_update_kernel_hostname(c);
        if (r < 0) {
                log_error_errno(r, "Failed to set host name: %m");
                return sd_bus_error_set_errnof(error, r, "Failed to set hostname: %m");
        }

        r = context_write_data_static_hostname(c);
        if (r < 0) {
                log_error_errno(r, "Failed to write static host name: %m");
                return sd_bus_error_set_errnof(error, r, "Failed to set static hostname: %m");
        }

        log_info("Changed static host name to '%s'", strna(c->data[PROP_STATIC_HOSTNAME]));

        (void) sd_bus_emit_properties_changed(sd_bus_message_get_bus(m), "/org/freedesktop/hostname1", "org.freedesktop.hostname1", "StaticHostname", NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int set_machine_info(Context *c, sd_bus_message *m, int prop, sd_bus_message_handler_t cb, sd_bus_error *error) {
        int interactive;
        const char *name;
        int r;

        assert(c);
        assert(m);

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

        name = empty_to_null(name);

        if (streq_ptr(name, c->data[prop]))
                return sd_bus_reply_method_return(m, NULL);

        if (!isempty(name)) {
                /* The icon name might ultimately be used as file
                 * name, so better be safe than sorry */

                if (prop == PROP_ICON_NAME && !filename_is_valid(name))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid icon name '%s'", name);
                if (prop == PROP_PRETTY_HOSTNAME && string_has_cc(name, NULL))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid pretty host name '%s'", name);
                if (prop == PROP_CHASSIS && !valid_chassis(name))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid chassis '%s'", name);
                if (prop == PROP_DEPLOYMENT && !valid_deployment(name))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid deployment '%s'", name);
                if (prop == PROP_LOCATION && string_has_cc(name, NULL))
                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid location '%s'", name);
        }

        /* Since the pretty hostname should always be changed at the
         * same time as the static one, use the same policy action for
         * both... */

        r = bus_verify_polkit_async(
                        m,
                        CAP_SYS_ADMIN,
                        prop == PROP_PRETTY_HOSTNAME ? "org.freedesktop.hostname1.set-static-hostname" : "org.freedesktop.hostname1.set-machine-info",
                        NULL,
                        interactive,
                        UID_INVALID,
                        &c->polkit_registry,
                        error);
        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 */

        r = free_and_strdup(&c->data[prop], name);
        if (r < 0)
                return r;

        r = context_write_data_machine_info(c);
        if (r < 0) {
                log_error_errno(r, "Failed to write machine info: %m");
                return sd_bus_error_set_errnof(error, r, "Failed to write machine info: %m");
        }

        log_info("Changed %s to '%s'",
                 prop == PROP_PRETTY_HOSTNAME ? "pretty host name" :
                 prop == PROP_DEPLOYMENT ? "deployment" :
                 prop == PROP_LOCATION ? "location" :
                 prop == PROP_CHASSIS ? "chassis" : "icon name", strna(c->data[prop]));

        (void) sd_bus_emit_properties_changed(
                        sd_bus_message_get_bus(m),
                        "/org/freedesktop/hostname1",
                        "org.freedesktop.hostname1",
                        prop == PROP_PRETTY_HOSTNAME ? "PrettyHostname" :
                        prop == PROP_DEPLOYMENT ? "Deployment" :
                        prop == PROP_LOCATION ? "Location" :
                        prop == PROP_CHASSIS ? "Chassis" : "IconName" , NULL);

        return sd_bus_reply_method_return(m, NULL);
}

static int method_set_pretty_hostname(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        return set_machine_info(userdata, m, PROP_PRETTY_HOSTNAME, method_set_pretty_hostname, error);
}

static int method_set_icon_name(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        return set_machine_info(userdata, m, PROP_ICON_NAME, method_set_icon_name, error);
}

static int method_set_chassis(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        return set_machine_info(userdata, m, PROP_CHASSIS, method_set_chassis, error);
}

static int method_set_deployment(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        return set_machine_info(userdata, m, PROP_DEPLOYMENT, method_set_deployment, error);
}

static int method_set_location(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        return set_machine_info(userdata, m, PROP_LOCATION, method_set_location, error);
}

static int method_get_product_uuid(sd_bus_message *m, void *userdata, sd_bus_error *error) {
        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
        Context *c = userdata;
        int interactive, r;

        assert(m);
        assert(c);

        if (!c->has_uuid)
                return sd_bus_error_set(error, BUS_ERROR_NO_PRODUCT_UUID, "Failed to read product UUID from /sys/class/dmi/id/product_uuid");

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

        r = bus_verify_polkit_async(
                        m,
                        CAP_SYS_ADMIN,
                        "org.freedesktop.hostname1.get-product-uuid",
                        NULL,
                        interactive,
                        UID_INVALID,
                        &c->polkit_registry,
                        error);
        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 */

        r = sd_bus_message_new_method_return(m, &reply);
        if (r < 0)
                return r;

        r = sd_bus_message_append_array(reply, 'y', &c->uuid, sizeof(c->uuid));
        if (r < 0)
                return r;

        return sd_bus_send(NULL, reply, NULL);
}

static const sd_bus_vtable hostname_vtable[] = {
        SD_BUS_VTABLE_START(0),
        SD_BUS_PROPERTY("Hostname", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_HOSTNAME, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("StaticHostname", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_STATIC_HOSTNAME, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("PrettyHostname", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_PRETTY_HOSTNAME, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("IconName", "s", property_get_icon_name, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("Chassis", "s", property_get_chassis, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("Deployment", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_DEPLOYMENT, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("Location", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_LOCATION, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
        SD_BUS_PROPERTY("KernelName", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_KERNEL_NAME, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_PROPERTY("KernelRelease", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_KERNEL_RELEASE, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_PROPERTY("KernelVersion", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_KERNEL_VERSION, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_PROPERTY("OperatingSystemPrettyName", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_OS_PRETTY_NAME, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_PROPERTY("OperatingSystemCPEName", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_OS_CPE_NAME, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_PROPERTY("HomeURL", "s", NULL, offsetof(Context, data) + sizeof(char*) * PROP_HOME_URL, SD_BUS_VTABLE_PROPERTY_CONST),
        SD_BUS_METHOD("SetHostname", "sb", NULL, method_set_hostname, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetStaticHostname", "sb", NULL, method_set_static_hostname, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetPrettyHostname", "sb", NULL, method_set_pretty_hostname, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetIconName", "sb", NULL, method_set_icon_name, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetChassis", "sb", NULL, method_set_chassis, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetDeployment", "sb", NULL, method_set_deployment, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("SetLocation", "sb", NULL, method_set_location, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_METHOD("GetProductUUID", "b", "ay", method_get_product_uuid, SD_BUS_VTABLE_UNPRIVILEGED),
        SD_BUS_VTABLE_END,
};

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

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

        r = sd_bus_default_system(&bus);
        if (r < 0)
                return log_error_errno(r, "Failed to get system bus connection: %m");

        r = sd_bus_add_object_vtable(bus, NULL, "/org/freedesktop/hostname1", "org.freedesktop.hostname1", hostname_vtable, c);
        if (r < 0)
                return log_error_errno(r, "Failed to register object: %m");

        r = sd_bus_request_name_async(bus, NULL, "org.freedesktop.hostname1", 0, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to request name: %m");

        r = sd_bus_attach_event(bus, event, 0);
        if (r < 0)
                return log_error_errno(r, "Failed to attach bus to event loop: %m");

        *_bus = TAKE_PTR(bus);

        return 0;
}

static int run(int argc, char *argv[]) {
        _cleanup_(context_clear) Context context = {};
        _cleanup_(sd_event_unrefp) sd_event *event = NULL;
        _cleanup_(sd_bus_flush_close_unrefp) sd_bus *bus = NULL;
        int r;

        log_setup_service();

        umask(0022);
        mac_selinux_init();

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

        assert_se(sigprocmask_many(SIG_BLOCK, NULL, SIGTERM, SIGINT, -1) >= 0);

        r = sd_event_default(&event);
        if (r < 0)
                return log_error_errno(r, "Failed to allocate event loop: %m");

        (void) sd_event_set_watchdog(event, true);

        r = sd_event_add_signal(event, NULL, SIGINT, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to install SIGINT handler: %m");

        r = sd_event_add_signal(event, NULL, SIGTERM, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to install SIGTERM handler: %m");

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

        r = context_read_data(&context);
        if (r < 0)
                return log_error_errno(r, "Failed to read hostname and machine information: %m");

        r = bus_event_loop_with_idle(event, bus, "org.freedesktop.hostname1", DEFAULT_EXIT_USEC, NULL, NULL);
        if (r < 0)
                return log_error_errno(r, "Failed to run event loop: %m");

        return 0;
}

DEFINE_MAIN_FUNCTION(run);