qemu-ga: move qemu-ga files to qga/

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 901 insertions, 0 deletions

diff --git a/qga/main.c b/qga/main.c
new file mode 100644
index 0000000000..9b59a52461
--- /dev/null
+++ b/qga/main.c
@@ -0,0 +1,901 @@
+/*
+ * 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 "json-streamer.h"
+#include "json-parser.h"
+#include "qint.h"
+#include "qjson.h"
+#include "qga/guest-agent-core.h"
+#include "module.h"
+#include "signal.h"
+#include "qerror.h"
+#include "qapi/qmp-core.h"
+#include "qga/channel.h"
+#ifdef _WIN32
+#include "qga/service-win32.h"
+#include <windows.h>
+#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"
+#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;
+};
+
+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-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"
+"  -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,
+    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;
+}
+
+#ifndef _WIN32
+static bool ga_open_pidfile(const char *pidfile)
+{
+    int pidfd;
+    char pidstr[32];
+
+    pidfd = 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) || lseek(pidfd, 0, SEEK_SET)) {
+        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;
+    }
+
+    return true;
+
+fail:
+    unlink(pidfile);
+    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 = fopen(s->deferred_options.log_filepath, "a");
+        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);
+    }
+}
+
+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;
+        }
+    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:b:s:t:";
+    const char *method = NULL, *path = NULL;
+    const char *log_filepath = NULL;
+    const char *pid_filepath = QGA_PIDFILE_DEFAULT;
+    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' },
+        { "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;
+        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;
+    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 = fopen(log_filepath, "a");
+            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;
+}