aboutsummaryrefslogtreecommitdiff
path: root/qga/main.c
blob: 74ef7885b251f93ad2b1f285170fa382fbac4278 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
/*
 * 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>
#include <glib/gstdio.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"
#include "qemu/bswap.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

typedef struct GAPersistentState {
#define QGA_PSTATE_DEFAULT_FD_COUNTER 1000
    int64_t fd_counter;
} GAPersistentState;

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
    const gchar *pstate_filepath;
    GAPersistentState pstate;
};

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

static void set_persistent_state_defaults(GAPersistentState *pstate)
{
    g_assert(pstate);
    pstate->fd_counter = QGA_PSTATE_DEFAULT_FD_COUNTER;
}

static void persistent_state_from_keyfile(GAPersistentState *pstate,
                                          GKeyFile *keyfile)
{
    g_assert(pstate);
    g_assert(keyfile);
    /* if any fields are missing, either because the file was tampered with
     * by agents of chaos, or because the field wasn't present at the time the
     * file was created, the best we can ever do is start over with the default
     * values. so load them now, and ignore any errors in accessing key-value
     * pairs
     */
    set_persistent_state_defaults(pstate);

    if (g_key_file_has_key(keyfile, "global", "fd_counter", NULL)) {
        pstate->fd_counter =
            g_key_file_get_integer(keyfile, "global", "fd_counter", NULL);
    }
}

static void persistent_state_to_keyfile(const GAPersistentState *pstate,
                                        GKeyFile *keyfile)
{
    g_assert(pstate);
    g_assert(keyfile);

    g_key_file_set_integer(keyfile, "global", "fd_counter", pstate->fd_counter);
}

static gboolean write_persistent_state(const GAPersistentState *pstate,
                                       const gchar *path)
{
    GKeyFile *keyfile = g_key_file_new();
    GError *gerr = NULL;
    gboolean ret = true;
    gchar *data = NULL;
    gsize data_len;

    g_assert(pstate);

    persistent_state_to_keyfile(pstate, keyfile);
    data = g_key_file_to_data(keyfile, &data_len, &gerr);
    if (gerr) {
        g_critical("failed to convert persistent state to string: %s",
                   gerr->message);
        ret = false;
        goto out;
    }

    g_file_set_contents(path, data, data_len, &gerr);
    if (gerr) {
        g_critical("failed to write persistent state to %s: %s",
                    path, gerr->message);
        ret = false;
        goto out;
    }

out:
    if (gerr) {
        g_error_free(gerr);
    }
    if (keyfile) {
        g_key_file_free(keyfile);
    }
    g_free(data);
    return ret;
}

static gboolean read_persistent_state(GAPersistentState *pstate,
                                      const gchar *path, gboolean frozen)
{
    GKeyFile *keyfile = NULL;
    GError *gerr = NULL;
    struct stat st;
    gboolean ret = true;

    g_assert(pstate);

    if (stat(path, &st) == -1) {
        /* it's okay if state file doesn't exist, but any other error
         * indicates a permissions issue or some other misconfiguration
         * that we likely won't be able to recover from.
         */
        if (errno != ENOENT) {
            g_critical("unable to access state file at path %s: %s",
                       path, strerror(errno));
            ret = false;
            goto out;
        }

        /* file doesn't exist. initialize state to default values and
         * attempt to save now. (we could wait till later when we have
         * modified state we need to commit, but if there's a problem,
         * such as a missing parent directory, we want to catch it now)
         *
         * there is a potential scenario where someone either managed to
         * update the agent from a version that didn't use a key store
         * while qemu-ga thought the filesystem was frozen, or
         * deleted the key store prior to issuing a fsfreeze, prior
         * to restarting the agent. in this case we go ahead and defer
         * initial creation till we actually have modified state to
         * write, otherwise fail to recover from freeze.
         */
        set_persistent_state_defaults(pstate);
        if (!frozen) {
            ret = write_persistent_state(pstate, path);
            if (!ret) {
                g_critical("unable to create state file at path %s", path);
                ret = false;
                goto out;
            }
        }
        ret = true;
        goto out;
    }

    keyfile = g_key_file_new();
    g_key_file_load_from_file(keyfile, path, 0, &gerr);
    if (gerr) {
        g_critical("error loading persistent state from path: %s, %s",
                   path, gerr->message);
        ret = false;
        goto out;
    }

    persistent_state_from_keyfile(pstate, keyfile);

out:
    if (keyfile) {
        g_key_file_free(keyfile);
    }
    if (gerr) {
        g_error_free(gerr);
    }

    return ret;
}

int64_t ga_get_fd_handle(GAState *s, Error **errp)
{
    int64_t handle;

    g_assert(s->pstate_filepath);
    /* we blacklist commands and avoid operations that potentially require
     * writing to disk when we're in a frozen state. this includes opening
     * new files, so we should never get here in that situation
     */
    g_assert(!ga_is_frozen(s));

    handle = s->pstate.fd_counter++;
    if (s->pstate.fd_counter < 0) {
        s->pstate.fd_counter = 0;
    }
    if (!write_persistent_state(&s->pstate, s->pstate_filepath)) {
        error_setg(errp, "failed to commit persistent state to disk");
    }

    return handle;
}

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->pstate_filepath = g_strdup_printf("%s/qga.state", 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;
        }
    }

    /* load persistent state from disk */
    if (!read_persistent_state(&s->pstate,
                               s->pstate_filepath,
                               ga_is_frozen(s))) {
        g_critical("failed to load persistent state");
        goto out_bad;
    }

    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;
}