Archipelago » qemu

/*

 * QEMU Guest Agent

 *

 * Copyright IBM Corp. 2011

 *

 * Authors:

 *  Adam Litke        <aglitke@linux.vnet.ibm.com>

 *  Michael Roth      <mdroth@linux.vnet.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */

#include <stdlib.h>

#include <stdio.h>

#include <stdbool.h>

#include <glib.h>

#include <getopt.h>

#ifndef _WIN32

#include <syslog.h>

#include <sys/wait.h>

#include <sys/stat.h>

#endif

#include "qapi/qmp/json-streamer.h"

#include "qapi/qmp/json-parser.h"

#include "qapi/qmp/qint.h"

#include "qapi/qmp/qjson.h"

#include "qga/guest-agent-core.h"

#include "qemu/module.h"

#include "signal.h"

#include "qapi/qmp/qerror.h"

#include "qapi/qmp/dispatch.h"

#include "qga/channel.h"

#ifdef _WIN32

#include "qga/service-win32.h"

#include <windows.h>

#endif

#ifdef __linux__

#include <linux/fs.h>

#ifdef FIFREEZE

#define CONFIG_FSFREEZE

#endif

#endif

#ifndef _WIN32

#define QGA_VIRTIO_PATH_DEFAULT "/dev/virtio-ports/org.qemu.guest_agent.0"

#else

#define QGA_VIRTIO_PATH_DEFAULT "\\\\.\\Global\\org.qemu.guest_agent.0"

#endif

#define QGA_STATEDIR_DEFAULT CONFIG_QEMU_LOCALSTATEDIR "/run"

#define QGA_PIDFILE_DEFAULT QGA_STATEDIR_DEFAULT "/qemu-ga.pid"

#ifdef CONFIG_FSFREEZE

#define QGA_FSFREEZE_HOOK_DEFAULT CONFIG_QEMU_CONFDIR "/fsfreeze-hook"

#endif

#define QGA_SENTINEL_BYTE 0xFF

struct GAState {

    JSONMessageParser parser;

    GMainLoop *main_loop;

    GAChannel *channel;

    bool virtio; /* fastpath to check for virtio to deal with poll() quirks */

    GACommandState *command_state;

    GLogLevelFlags log_level;

    FILE *log_file;

    bool logging_enabled;

#ifdef _WIN32

    GAService service;

#endif

    bool delimit_response;

    bool frozen;

    GList *blacklist;

    const char *state_filepath_isfrozen;

    struct {

        const char *log_filepath;

        const char *pid_filepath;

    } deferred_options;

#ifdef CONFIG_FSFREEZE

    const char *fsfreeze_hook;

#endif

};

struct GAState *ga_state;

/* commands that are safe to issue while filesystems are frozen */

static const char *ga_freeze_whitelist[] = {

    "guest-ping",

    "guest-info",

    "guest-sync",

    "guest-sync-delimited",

    "guest-fsfreeze-status",

    "guest-fsfreeze-thaw",

    NULL

};

#ifdef _WIN32

DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,

                                  LPVOID ctx);

VOID WINAPI service_main(DWORD argc, TCHAR *argv[]);

#endif

static void quit_handler(int sig)

{

    /* if we're frozen, don't exit unless we're absolutely forced to,

     * because it's basically impossible for graceful exit to complete

     * unless all log/pid files are on unfreezable filesystems. there's

     * also a very likely chance killing the agent before unfreezing

     * the filesystems is a mistake (or will be viewed as one later).

     */

    if (ga_is_frozen(ga_state)) {

        return;

    }

    g_debug("received signal num %d, quitting", sig);

    if (g_main_loop_is_running(ga_state->main_loop)) {

        g_main_loop_quit(ga_state->main_loop);

    }

}

#ifndef _WIN32

static gboolean register_signal_handlers(void)

{

    struct sigaction sigact;

    int ret;

    memset(&sigact, 0, sizeof(struct sigaction));

    sigact.sa_handler = quit_handler;

    ret = sigaction(SIGINT, &sigact, NULL);

    if (ret == -1) {

        g_error("error configuring signal handler: %s", strerror(errno));

    }

    ret = sigaction(SIGTERM, &sigact, NULL);

    if (ret == -1) {

        g_error("error configuring signal handler: %s", strerror(errno));

    }

    return true;

}

/* TODO: use this in place of all post-fork() fclose(std*) callers */

void reopen_fd_to_null(int fd)

{

    int nullfd;

    nullfd = open("/dev/null", O_RDWR);

    if (nullfd < 0) {

        return;

    }

    dup2(nullfd, fd);

    if (nullfd != fd) {

        close(nullfd);

    }

}

#endif

static void usage(const char *cmd)

{

    printf(

"Usage: %s [-m <method> -p <path>] [<options>]\n"

"QEMU Guest Agent %s\n"

"\n"

"  -m, --method      transport method: one of unix-listen, virtio-serial, or\n"

"                    isa-serial (virtio-serial is the default)\n"

"  -p, --path        device/socket path (the default for virtio-serial is:\n"

"                    %s)\n"

"  -l, --logfile     set logfile path, logs to stderr by default\n"

"  -f, --pidfile     specify pidfile (default is %s)\n"

#ifdef CONFIG_FSFREEZE

"  -F, --fsfreeze-hook\n"

"                    enable fsfreeze hook. Accepts an optional argument that\n"

"                    specifies script to run on freeze/thaw. Script will be\n"

"                    called with 'freeze'/'thaw' arguments accordingly.\n"

"                    (default is %s)\n"

"                    If using -F with an argument, do not follow -F with a\n"

"                    space.\n"

"                    (for example: -F/var/run/fsfreezehook.sh)\n"

#endif

"  -t, --statedir    specify dir to store state information (absolute paths\n"

"                    only, default is %s)\n"

"  -v, --verbose     log extra debugging information\n"

"  -V, --version     print version information and exit\n"

"  -d, --daemonize   become a daemon\n"

#ifdef _WIN32

"  -s, --service     service commands: install, uninstall\n"

#endif

"  -b, --blacklist   comma-separated list of RPCs to disable (no spaces, \"?\"\n"

"                    to list available RPCs)\n"

"  -h, --help        display this help and exit\n"

"\n"

"Report bugs to <mdroth@linux.vnet.ibm.com>\n"

    , cmd, QEMU_VERSION, QGA_VIRTIO_PATH_DEFAULT, QGA_PIDFILE_DEFAULT,

#ifdef CONFIG_FSFREEZE

    QGA_FSFREEZE_HOOK_DEFAULT,

#endif

    QGA_STATEDIR_DEFAULT);

}

static const char *ga_log_level_str(GLogLevelFlags level)

{

    switch (level & G_LOG_LEVEL_MASK) {

        case G_LOG_LEVEL_ERROR:

            return "error";

        case G_LOG_LEVEL_CRITICAL:

            return "critical";

        case G_LOG_LEVEL_WARNING:

            return "warning";

        case G_LOG_LEVEL_MESSAGE:

            return "message";

        case G_LOG_LEVEL_INFO:

            return "info";

        case G_LOG_LEVEL_DEBUG:

            return "debug";

        default:

            return "user";

    }

}

bool ga_logging_enabled(GAState *s)

{

    return s->logging_enabled;

}

void ga_disable_logging(GAState *s)

{

    s->logging_enabled = false;

}

void ga_enable_logging(GAState *s)

{

    s->logging_enabled = true;

}

static void ga_log(const gchar *domain, GLogLevelFlags level,

                   const gchar *msg, gpointer opaque)

{

    GAState *s = opaque;

    GTimeVal time;

    const char *level_str = ga_log_level_str(level);

    if (!ga_logging_enabled(s)) {

        return;

    }

    level &= G_LOG_LEVEL_MASK;

#ifndef _WIN32

    if (domain && strcmp(domain, "syslog") == 0) {

        syslog(LOG_INFO, "%s: %s", level_str, msg);

    } else if (level & s->log_level) {

#else

    if (level & s->log_level) {

#endif

        g_get_current_time(&time);

        fprintf(s->log_file,

                "%lu.%lu: %s: %s\n", time.tv_sec, time.tv_usec, level_str, msg);

        fflush(s->log_file);

    }

}

void ga_set_response_delimited(GAState *s)

{

    s->delimit_response = true;

}

static FILE *ga_open_logfile(const char *logfile)

{

    FILE *f;

    f = fopen(logfile, "a");

    if (!f) {

        return NULL;

    }

    qemu_set_cloexec(fileno(f));

    return f;

}

#ifndef _WIN32

static bool ga_open_pidfile(const char *pidfile)

{

    int pidfd;

    char pidstr[32];

    pidfd = qemu_open(pidfile, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR);

    if (pidfd == -1 || lockf(pidfd, F_TLOCK, 0)) {

        g_critical("Cannot lock pid file, %s", strerror(errno));

        if (pidfd != -1) {

            close(pidfd);

        }

        return false;

    }

    if (ftruncate(pidfd, 0)) {

        g_critical("Failed to truncate pid file");

        goto fail;

    }

    snprintf(pidstr, sizeof(pidstr), "%d\n", getpid());

    if (write(pidfd, pidstr, strlen(pidstr)) != strlen(pidstr)) {

        g_critical("Failed to write pid file");

        goto fail;

    }

    /* keep pidfile open & locked forever */

    return true;

fail:

    unlink(pidfile);

    close(pidfd);

    return false;

}

#else /* _WIN32 */

static bool ga_open_pidfile(const char *pidfile)

{

    return true;

}

#endif

static gint ga_strcmp(gconstpointer str1, gconstpointer str2)

{

    return strcmp(str1, str2);

}

/* disable commands that aren't safe for fsfreeze */

static void ga_disable_non_whitelisted(void)

{

    char **list_head, **list;

    bool whitelisted;

    int i;

    list_head = list = qmp_get_command_list();

    while (*list != NULL) {

        whitelisted = false;

        i = 0;

        while (ga_freeze_whitelist[i] != NULL) {

            if (strcmp(*list, ga_freeze_whitelist[i]) == 0) {

                whitelisted = true;

            }

            i++;

        }

        if (!whitelisted) {

            g_debug("disabling command: %s", *list);

            qmp_disable_command(*list);

        }

        g_free(*list);

        list++;

    }

    g_free(list_head);

}

/* [re-]enable all commands, except those explicitly blacklisted by user */

static void ga_enable_non_blacklisted(GList *blacklist)

{

    char **list_head, **list;

    list_head = list = qmp_get_command_list();

    while (*list != NULL) {

        if (g_list_find_custom(blacklist, *list, ga_strcmp) == NULL &&

            !qmp_command_is_enabled(*list)) {

            g_debug("enabling command: %s", *list);

            qmp_enable_command(*list);

        }

        g_free(*list);

        list++;

    }

    g_free(list_head);

}

static bool ga_create_file(const char *path)

{

    int fd = open(path, O_CREAT | O_WRONLY, S_IWUSR | S_IRUSR);

    if (fd == -1) {

        g_warning("unable to open/create file %s: %s", path, strerror(errno));

        return false;

    }

    close(fd);

    return true;

}

static bool ga_delete_file(const char *path)

{

    int ret = unlink(path);

    if (ret == -1) {

        g_warning("unable to delete file: %s: %s", path, strerror(errno));

        return false;

    }

    return true;

}

bool ga_is_frozen(GAState *s)

{

    return s->frozen;

}

void ga_set_frozen(GAState *s)

{

    if (ga_is_frozen(s)) {

        return;

    }

    /* disable all non-whitelisted (for frozen state) commands */

    ga_disable_non_whitelisted();

    g_warning("disabling logging due to filesystem freeze");

    ga_disable_logging(s);

    s->frozen = true;

    if (!ga_create_file(s->state_filepath_isfrozen)) {

        g_warning("unable to create %s, fsfreeze may not function properly",

                  s->state_filepath_isfrozen);

    }

}

void ga_unset_frozen(GAState *s)

{

    if (!ga_is_frozen(s)) {

        return;

    }

    /* if we delayed creation/opening of pid/log files due to being

     * in a frozen state at start up, do it now

     */

    if (s->deferred_options.log_filepath) {

        s->log_file = ga_open_logfile(s->deferred_options.log_filepath);

        if (!s->log_file) {

            s->log_file = stderr;

        }

        s->deferred_options.log_filepath = NULL;

    }

    ga_enable_logging(s);

    g_warning("logging re-enabled due to filesystem unfreeze");

    if (s->deferred_options.pid_filepath) {

        if (!ga_open_pidfile(s->deferred_options.pid_filepath)) {

            g_warning("failed to create/open pid file");

        }

        s->deferred_options.pid_filepath = NULL;

    }

    /* enable all disabled, non-blacklisted commands */

    ga_enable_non_blacklisted(s->blacklist);

    s->frozen = false;

    if (!ga_delete_file(s->state_filepath_isfrozen)) {

        g_warning("unable to delete %s, fsfreeze may not function properly",

                  s->state_filepath_isfrozen);

    }

}

#ifdef CONFIG_FSFREEZE

const char *ga_fsfreeze_hook(GAState *s)

{

    return s->fsfreeze_hook;

}

#endif

static void become_daemon(const char *pidfile)

{

#ifndef _WIN32

    pid_t pid, sid;

    pid = fork();

    if (pid < 0) {

        exit(EXIT_FAILURE);

    }

    if (pid > 0) {

        exit(EXIT_SUCCESS);

    }

    if (pidfile) {

        if (!ga_open_pidfile(pidfile)) {

            g_critical("failed to create pidfile");

            exit(EXIT_FAILURE);

        }

    }

    umask(0);

    sid = setsid();

    if (sid < 0) {

        goto fail;

    }

    if ((chdir("/")) < 0) {

        goto fail;

    }

    reopen_fd_to_null(STDIN_FILENO);

    reopen_fd_to_null(STDOUT_FILENO);

    reopen_fd_to_null(STDERR_FILENO);

    return;

fail:

    if (pidfile) {

        unlink(pidfile);

    }

    g_critical("failed to daemonize");

    exit(EXIT_FAILURE);

#endif

}

static int send_response(GAState *s, QObject *payload)

{

    const char *buf;

    QString *payload_qstr, *response_qstr;

    GIOStatus status;

    g_assert(payload && s->channel);

    payload_qstr = qobject_to_json(payload);

    if (!payload_qstr) {

        return -EINVAL;

    }

    if (s->delimit_response) {

        s->delimit_response = false;

        response_qstr = qstring_new();

        qstring_append_chr(response_qstr, QGA_SENTINEL_BYTE);

        qstring_append(response_qstr, qstring_get_str(payload_qstr));

        QDECREF(payload_qstr);

    } else {

        response_qstr = payload_qstr;

    }

    qstring_append_chr(response_qstr, '\n');

    buf = qstring_get_str(response_qstr);

    status = ga_channel_write_all(s->channel, buf, strlen(buf));

    QDECREF(response_qstr);

    if (status != G_IO_STATUS_NORMAL) {

        return -EIO;

    }

    return 0;

}

static void process_command(GAState *s, QDict *req)

{

    QObject *rsp = NULL;

    int ret;

    g_assert(req);

    g_debug("processing command");

    rsp = qmp_dispatch(QOBJECT(req));

    if (rsp) {

        ret = send_response(s, rsp);

        if (ret) {

            g_warning("error sending response: %s", strerror(ret));

        }

        qobject_decref(rsp);

    }

}

/* handle requests/control events coming in over the channel */

static void process_event(JSONMessageParser *parser, QList *tokens)

{

    GAState *s = container_of(parser, GAState, parser);

    QObject *obj;

    QDict *qdict;

    Error *err = NULL;

    int ret;

    g_assert(s && parser);

    g_debug("process_event: called");

    obj = json_parser_parse_err(tokens, NULL, &err);

    if (err || !obj || qobject_type(obj) != QTYPE_QDICT) {

        qobject_decref(obj);

        qdict = qdict_new();

        if (!err) {

            g_warning("failed to parse event: unknown error");

            error_set(&err, QERR_JSON_PARSING);

        } else {

            g_warning("failed to parse event: %s", error_get_pretty(err));

        }

        qdict_put_obj(qdict, "error", qmp_build_error_object(err));

        error_free(err);

    } else {

        qdict = qobject_to_qdict(obj);

    }

    g_assert(qdict);

    /* handle host->guest commands */

    if (qdict_haskey(qdict, "execute")) {

        process_command(s, qdict);

    } else {

        if (!qdict_haskey(qdict, "error")) {

            QDECREF(qdict);

            qdict = qdict_new();

            g_warning("unrecognized payload format");

            error_set(&err, QERR_UNSUPPORTED);

            qdict_put_obj(qdict, "error", qmp_build_error_object(err));

            error_free(err);

        }

        ret = send_response(s, QOBJECT(qdict));

        if (ret) {

            g_warning("error sending error response: %s", strerror(ret));

        }

    }

    QDECREF(qdict);

}

/* false return signals GAChannel to close the current client connection */

static gboolean channel_event_cb(GIOCondition condition, gpointer data)

{

    GAState *s = data;

    gchar buf[QGA_READ_COUNT_DEFAULT+1];

    gsize count;

    GError *err = NULL;

    GIOStatus status = ga_channel_read(s->channel, buf, QGA_READ_COUNT_DEFAULT, &count);

    if (err != NULL) {

        g_warning("error reading channel: %s", err->message);

        g_error_free(err);

        return false;

    }

    switch (status) {

    case G_IO_STATUS_ERROR:

        g_warning("error reading channel");

        return false;

    case G_IO_STATUS_NORMAL:

        buf[count] = 0;

        g_debug("read data, count: %d, data: %s", (int)count, buf);

        json_message_parser_feed(&s->parser, (char *)buf, (int)count);

        break;

    case G_IO_STATUS_EOF:

        g_debug("received EOF");

        if (!s->virtio) {

            return false;

        }

        /* fall through */

    case G_IO_STATUS_AGAIN:

        /* virtio causes us to spin here when no process is attached to

         * host-side chardev. sleep a bit to mitigate this

         */

        if (s->virtio) {

            usleep(100*1000);

        }

        return true;

    default:

        g_warning("unknown channel read status, closing");

        return false;

    }

    return true;

}

static gboolean channel_init(GAState *s, const gchar *method, const gchar *path)

{

    GAChannelMethod channel_method;

    if (method == NULL) {

        method = "virtio-serial";

    }

    if (path == NULL) {

        if (strcmp(method, "virtio-serial") != 0) {

            g_critical("must specify a path for this channel");

            return false;

        }

        /* try the default path for the virtio-serial port */

        path = QGA_VIRTIO_PATH_DEFAULT;

    }

    if (strcmp(method, "virtio-serial") == 0) {

        s->virtio = true; /* virtio requires special handling in some cases */

        channel_method = GA_CHANNEL_VIRTIO_SERIAL;

    } else if (strcmp(method, "isa-serial") == 0) {

        channel_method = GA_CHANNEL_ISA_SERIAL;

    } else if (strcmp(method, "unix-listen") == 0) {

        channel_method = GA_CHANNEL_UNIX_LISTEN;

    } else {

        g_critical("unsupported channel method/type: %s", method);

        return false;

    }

    s->channel = ga_channel_new(channel_method, path, channel_event_cb, s);

    if (!s->channel) {

        g_critical("failed to create guest agent channel");

        return false;

    }

    return true;

}

#ifdef _WIN32

DWORD WINAPI service_ctrl_handler(DWORD ctrl, DWORD type, LPVOID data,

                                  LPVOID ctx)

{

    DWORD ret = NO_ERROR;

    GAService *service = &ga_state->service;

    switch (ctrl)

    {

        case SERVICE_CONTROL_STOP:

        case SERVICE_CONTROL_SHUTDOWN:

            quit_handler(SIGTERM);

            service->status.dwCurrentState = SERVICE_STOP_PENDING;

            SetServiceStatus(service->status_handle, &service->status);

            break;

        default:

            ret = ERROR_CALL_NOT_IMPLEMENTED;

    }

    return ret;

}

VOID WINAPI service_main(DWORD argc, TCHAR *argv[])

{

    GAService *service = &ga_state->service;

    service->status_handle = RegisterServiceCtrlHandlerEx(QGA_SERVICE_NAME,

        service_ctrl_handler, NULL);

    if (service->status_handle == 0) {

        g_critical("Failed to register extended requests function!\n");

        return;

    }

    service->status.dwServiceType = SERVICE_WIN32;

    service->status.dwCurrentState = SERVICE_RUNNING;

    service->status.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;

    service->status.dwWin32ExitCode = NO_ERROR;

    service->status.dwServiceSpecificExitCode = NO_ERROR;

    service->status.dwCheckPoint = 0;

    service->status.dwWaitHint = 0;

    SetServiceStatus(service->status_handle, &service->status);

    g_main_loop_run(ga_state->main_loop);

    service->status.dwCurrentState = SERVICE_STOPPED;

    SetServiceStatus(service->status_handle, &service->status);

}

#endif

int main(int argc, char **argv)

{

    const char *sopt = "hVvdm:p:l:f:F::b:s:t:";

    const char *method = NULL, *path = NULL;

    const char *log_filepath = NULL;

    const char *pid_filepath = QGA_PIDFILE_DEFAULT;

#ifdef CONFIG_FSFREEZE

    const char *fsfreeze_hook = NULL;

#endif

    const char *state_dir = QGA_STATEDIR_DEFAULT;

#ifdef _WIN32

    const char *service = NULL;

#endif

    const struct option lopt[] = {

        { "help", 0, NULL, 'h' },

        { "version", 0, NULL, 'V' },

        { "logfile", 1, NULL, 'l' },

        { "pidfile", 1, NULL, 'f' },

#ifdef CONFIG_FSFREEZE

        { "fsfreeze-hook", 2, NULL, 'F' },

#endif

        { "verbose", 0, NULL, 'v' },

        { "method", 1, NULL, 'm' },

        { "path", 1, NULL, 'p' },

        { "daemonize", 0, NULL, 'd' },

        { "blacklist", 1, NULL, 'b' },

#ifdef _WIN32

        { "service", 1, NULL, 's' },

#endif

        { "statedir", 1, NULL, 't' },

        { NULL, 0, NULL, 0 }

    };

    int opt_ind = 0, ch, daemonize = 0, i, j, len;

    GLogLevelFlags log_level = G_LOG_LEVEL_ERROR | G_LOG_LEVEL_CRITICAL;

    GList *blacklist = NULL;

    GAState *s;

    module_call_init(MODULE_INIT_QAPI);

    while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {

        switch (ch) {

        case 'm':

            method = optarg;

            break;

        case 'p':

            path = optarg;

            break;

        case 'l':

            log_filepath = optarg;

            break;

        case 'f':

            pid_filepath = optarg;

            break;

#ifdef CONFIG_FSFREEZE

        case 'F':

            fsfreeze_hook = optarg ? optarg : QGA_FSFREEZE_HOOK_DEFAULT;

            break;

#endif

        case 't':

             state_dir = optarg;

             break;

        case 'v':

            /* enable all log levels */

            log_level = G_LOG_LEVEL_MASK;

            break;

        case 'V':

            printf("QEMU Guest Agent %s\n", QEMU_VERSION);

            return 0;

        case 'd':

            daemonize = 1;

            break;

        case 'b': {

            char **list_head, **list;

            if (is_help_option(optarg)) {

                list_head = list = qmp_get_command_list();

                while (*list != NULL) {

                    printf("%s\n", *list);

                    g_free(*list);

                    list++;

                }

                g_free(list_head);

                return 0;

            }

            for (j = 0, i = 0, len = strlen(optarg); i < len; i++) {

                if (optarg[i] == ',') {

                    optarg[i] = 0;

                    blacklist = g_list_append(blacklist, &optarg[j]);

                    j = i + 1;

                }

            }

            if (j < i) {

                blacklist = g_list_append(blacklist, &optarg[j]);

            }

            break;

        }

#ifdef _WIN32

        case 's':

            service = optarg;

            if (strcmp(service, "install") == 0) {

                return ga_install_service(path, log_filepath);

            } else if (strcmp(service, "uninstall") == 0) {

                return ga_uninstall_service();

            } else {

                printf("Unknown service command.\n");

                return EXIT_FAILURE;

            }

            break;

#endif

        case 'h':

            usage(argv[0]);

            return 0;

        case '?':

            g_print("Unknown option, try '%s --help' for more information.\n",

                    argv[0]);

            return EXIT_FAILURE;

        }

    }

    s = g_malloc0(sizeof(GAState));

    s->log_level = log_level;

    s->log_file = stderr;

#ifdef CONFIG_FSFREEZE

    s->fsfreeze_hook = fsfreeze_hook;

#endif

    g_log_set_default_handler(ga_log, s);

    g_log_set_fatal_mask(NULL, G_LOG_LEVEL_ERROR);

    ga_enable_logging(s);

    s->state_filepath_isfrozen = g_strdup_printf("%s/qga.state.isfrozen",

                                                 state_dir);

    s->frozen = false;

#ifndef _WIN32

    /* check if a previous instance of qemu-ga exited with filesystems' state

     * marked as frozen. this could be a stale value (a non-qemu-ga process

     * or reboot may have since unfrozen them), but better to require an

     * uneeded unfreeze than to risk hanging on start-up

     */

    struct stat st;

    if (stat(s->state_filepath_isfrozen, &st) == -1) {

        /* it's okay if the file doesn't exist, but if we can't access for

         * some other reason, such as permissions, there's a configuration

         * that needs to be addressed. so just bail now before we get into

         * more trouble later

         */

        if (errno != ENOENT) {

            g_critical("unable to access state file at path %s: %s",

                       s->state_filepath_isfrozen, strerror(errno));

            return EXIT_FAILURE;

        }

    } else {

        g_warning("previous instance appears to have exited with frozen"

                  " filesystems. deferring logging/pidfile creation and"

                  " disabling non-fsfreeze-safe commands until"

                  " guest-fsfreeze-thaw is issued, or filesystems are"

                  " manually unfrozen and the file %s is removed",

                  s->state_filepath_isfrozen);

        s->frozen = true;

    }

#endif

    if (ga_is_frozen(s)) {

        if (daemonize) {

            /* delay opening/locking of pidfile till filesystem are unfrozen */

            s->deferred_options.pid_filepath = pid_filepath;

            become_daemon(NULL);

        }

        if (log_filepath) {

            /* delay opening the log file till filesystems are unfrozen */

            s->deferred_options.log_filepath = log_filepath;

        }

        ga_disable_logging(s);

        ga_disable_non_whitelisted();

    } else {

        if (daemonize) {

            become_daemon(pid_filepath);

        }

        if (log_filepath) {

            FILE *log_file = ga_open_logfile(log_filepath);

            if (!log_file) {

                g_critical("unable to open specified log file: %s",

                           strerror(errno));

                goto out_bad;

            }

            s->log_file = log_file;

        }

    }

    if (blacklist) {

        s->blacklist = blacklist;

        do {

            g_debug("disabling command: %s", (char *)blacklist->data);

            qmp_disable_command(blacklist->data);

            blacklist = g_list_next(blacklist);

        } while (blacklist);

    }

    s->command_state = ga_command_state_new();

    ga_command_state_init(s, s->command_state);

    ga_command_state_init_all(s->command_state);

    json_message_parser_init(&s->parser, process_event);

    ga_state = s;

#ifndef _WIN32

    if (!register_signal_handlers()) {

        g_critical("failed to register signal handlers");

        goto out_bad;

    }

#endif

    s->main_loop = g_main_loop_new(NULL, false);

    if (!channel_init(ga_state, method, path)) {

        g_critical("failed to initialize guest agent channel");

        goto out_bad;

    }

#ifndef _WIN32

    g_main_loop_run(ga_state->main_loop);

#else

    if (daemonize) {

        SERVICE_TABLE_ENTRY service_table[] = {

            { (char *)QGA_SERVICE_NAME, service_main }, { NULL, NULL } };

        StartServiceCtrlDispatcher(service_table);

    } else {

        g_main_loop_run(ga_state->main_loop);

    }

#endif

    ga_command_state_cleanup_all(ga_state->command_state);

    ga_channel_free(ga_state->channel);

    if (daemonize) {

        unlink(pid_filepath);

    }

    return 0;

out_bad:

    if (daemonize) {

        unlink(pid_filepath);

    }

    return EXIT_FAILURE;

}