qemu-nbd.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu-common.h"
  20 #include "sysemu/block-backend.h"
  21 #include "block/block_int.h"
  22 #include "block/nbd.h"
  23 #include "qemu/main-loop.h"
  24 #include "qemu/sockets.h"
  25 #include "qemu/error-report.h"
  26 #include "block/snapshot.h"
  27 #include "qapi/util.h"
  28 #include "qapi/qmp/qstring.h"
  29
  30 #include <stdarg.h>
  31 #include <stdio.h>
  32 #include <getopt.h>
  33 #include <err.h>
  34 #include <sys/types.h>
  35 #include <sys/socket.h>
  36 #include <netinet/in.h>
  37 #include <netinet/tcp.h>
  38 #include <arpa/inet.h>
  39 #include <signal.h>
  40 #include <libgen.h>
  41 #include <pthread.h>
  42
  43 #define SOCKET_PATH                "/var/lock/qemu-nbd-%s"
  44 #define QEMU_NBD_OPT_CACHE         1
  45 #define QEMU_NBD_OPT_AIO           2
  46 #define QEMU_NBD_OPT_DISCARD       3
  47 #define QEMU_NBD_OPT_DETECT_ZEROES 4
  48
  49 static NBDExport *exp;
  50 static int verbose;
  51 static char *srcpath;
  52 static SocketAddress *saddr;
  53 static int persistent = 0;
  54 static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
  55 static int shared = 1;
  56 static int nb_fds;
  57 static int server_fd;
  58
  59 static void usage(const char *name)
  60 {
  61     (printf) (
  62 "Usage: %s [OPTIONS] FILE\n"
  63 "QEMU Disk Network Block Device Server\n"
  64 "\n"
  65 "  -h, --help                display this help and exit\n"
  66 "  -V, --version             output version information and exit\n"
  67 "\n"
  68 "Connection properties:\n"
  69 "  -p, --port=PORT           port to listen on (default `%d')\n"
  70 "  -b, --bind=IFACE          interface to bind to (default `0.0.0.0')\n"
  71 "  -k, --socket=PATH         path to the unix socket\n"
  72 "                            (default '"SOCKET_PATH"')\n"
  73 "  -e, --shared=NUM          device can be shared by NUM clients (default '1')\n"
  74 "  -t, --persistent          don't exit on the last connection\n"
  75 "  -v, --verbose             display extra debugging information\n"
  76 "\n"
  77 "Exposing part of the image:\n"
  78 "  -o, --offset=OFFSET       offset into the image\n"
  79 "  -P, --partition=NUM       only expose partition NUM\n"
  80 "\n"
  81 #ifdef __linux__
  82 "Kernel NBD client support:\n"
  83 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
  84 "  -d, --disconnect          disconnect the specified device\n"
  85 "\n"
  86 #endif
  87 "\n"
  88 "Block device options:\n"
  89 "  -f, --format=FORMAT       set image format (raw, qcow2, ...)\n"
  90 "  -r, --read-only           export read-only\n"
  91 "  -s, --snapshot            use FILE as an external snapshot, create a temporary\n"
  92 "                            file with backing_file=FILE, redirect the write to\n"
  93 "                            the temporary one\n"
  94 "  -l, --load-snapshot=SNAPSHOT_PARAM\n"
  95 "                            load an internal snapshot inside FILE and export it\n"
  96 "                            as an read-only device, SNAPSHOT_PARAM format is\n"
  97 "                            'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
  98 "                            '[ID_OR_NAME]'\n"
  99 "  -n, --nocache             disable host cache\n"
 100 "      --cache=MODE          set cache mode (none, writeback, ...)\n"
 101 #ifdef CONFIG_LINUX_AIO
 102 "      --aio=MODE            set AIO mode (native or threads)\n"
 103 #endif
 104 "      --discard=MODE        set discard mode (ignore, unmap)\n"
 105 "      --detect-zeroes=MODE  set detect-zeroes mode (off, on, unmap)\n"
 106 "\n"
 107 "Report bugs to <qemu-devel@nongnu.org>\n"
 108     , name, NBD_DEFAULT_PORT, "DEVICE");
 109 }
 110
 111 static void version(const char *name)
 112 {
 113     printf(
 114 "%s version 0.0.1\n"
 115 "Written by Anthony Liguori.\n"
 116 "\n"
 117 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
 118 "This is free software; see the source for copying conditions.  There is NO\n"
 119 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 120     , name);
 121 }
 122
 123 struct partition_record
 124 {
 125     uint8_t bootable;
 126     uint8_t start_head;
 127     uint32_t start_cylinder;
 128     uint8_t start_sector;
 129     uint8_t system;
 130     uint8_t end_head;
 131     uint8_t end_cylinder;
 132     uint8_t end_sector;
 133     uint32_t start_sector_abs;
 134     uint32_t nb_sectors_abs;
 135 };
 136
 137 static void read_partition(uint8_t *p, struct partition_record *r)
 138 {
 139     r->bootable = p[0];
 140     r->start_head = p[1];
 141     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
 142     r->start_sector = p[2] & 0x3f;
 143     r->system = p[4];
 144     r->end_head = p[5];
 145     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 146     r->end_sector = p[6] & 0x3f;
 147
 148     r->start_sector_abs = le32_to_cpup((uint32_t *)(p +  8));
 149     r->nb_sectors_abs   = le32_to_cpup((uint32_t *)(p + 12));
 150 }
 151
 152 static int find_partition(BlockBackend *blk, int partition,
 153                           off_t *offset, off_t *size)
 154 {
 155     struct partition_record mbr[4];
 156     uint8_t data[512];
 157     int i;
 158     int ext_partnum = 4;
 159     int ret;
 160
 161     if ((ret = blk_read(blk, 0, data, 1)) < 0) {
 162         errno = -ret;
 163         err(EXIT_FAILURE, "error while reading");
 164     }
 165
 166     if (data[510] != 0x55 || data[511] != 0xaa) {
 167         return -EINVAL;
 168     }
 169
 170     for (i = 0; i < 4; i++) {
 171         read_partition(&data[446 + 16 * i], &mbr[i]);
 172
 173         if (!mbr[i].system || !mbr[i].nb_sectors_abs) {
 174             continue;
 175         }
 176
 177         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 178             struct partition_record ext[4];
 179             uint8_t data1[512];
 180             int j;
 181
 182             if ((ret = blk_read(blk, mbr[i].start_sector_abs, data1, 1)) < 0) {
 183                 errno = -ret;
 184                 err(EXIT_FAILURE, "error while reading");
 185             }
 186
 187             for (j = 0; j < 4; j++) {
 188                 read_partition(&data1[446 + 16 * j], &ext[j]);
 189                 if (!ext[j].system || !ext[j].nb_sectors_abs) {
 190                     continue;
 191                 }
 192
 193                 if ((ext_partnum + j + 1) == partition) {
 194                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 195                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 196                     return 0;
 197                 }
 198             }
 199             ext_partnum += 4;
 200         } else if ((i + 1) == partition) {
 201             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 202             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 203             return 0;
 204         }
 205     }
 206
 207     return -ENOENT;
 208 }
 209
 210 static void termsig_handler(int signum)
 211 {
 212     state = TERMINATE;
 213     qemu_notify_event();
 214 }
 215
 216
 217 static void *show_parts(void *arg)
 218 {
 219     char *device = arg;
 220     int nbd;
 221
 222     /* linux just needs an open() to trigger
 223      * the partition table update
 224      * but remember to load the module with max_part != 0 :
 225      *     modprobe nbd max_part=63
 226      */
 227     nbd = open(device, O_RDWR);
 228     if (nbd >= 0) {
 229         close(nbd);
 230     }
 231     return NULL;
 232 }
 233
 234 static void *nbd_client_thread(void *arg)
 235 {
 236     char *device = arg;
 237     off_t size;
 238     uint32_t nbdflags;
 239     int fd, sock;
 240     int ret;
 241     pthread_t show_parts_thread;
 242     Error *local_error = NULL;
 243
 244
 245     sock = socket_connect(saddr, &local_error, NULL, NULL);
 246     if (sock < 0) {
 247         error_report_err(local_error);
 248         goto out;
 249     }
 250
 251     ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 252                                 &size, &local_error);
 253     if (ret < 0) {
 254         if (local_error) {
 255             fprintf(stderr, "%s\n", error_get_pretty(local_error));
 256             error_free(local_error);
 257         }
 258         goto out_socket;
 259     }
 260
 261     fd = open(device, O_RDWR);
 262     if (fd < 0) {
 263         /* Linux-only, we can use %m in printf.  */
 264         fprintf(stderr, "Failed to open %s: %m\n", device);
 265         goto out_socket;
 266     }
 267
 268     ret = nbd_init(fd, sock, nbdflags, size);
 269     if (ret < 0) {
 270         goto out_fd;
 271     }
 272
 273     /* update partition table */
 274     pthread_create(&show_parts_thread, NULL, show_parts, device);
 275
 276     if (verbose) {
 277         fprintf(stderr, "NBD device %s is now connected to %s\n",
 278                 device, srcpath);
 279     } else {
 280         /* Close stderr so that the qemu-nbd process exits.  */
 281         dup2(STDOUT_FILENO, STDERR_FILENO);
 282     }
 283
 284     ret = nbd_client(fd);
 285     if (ret) {
 286         goto out_fd;
 287     }
 288     close(fd);
 289     kill(getpid(), SIGTERM);
 290     return (void *) EXIT_SUCCESS;
 291
 292 out_fd:
 293     close(fd);
 294 out_socket:
 295     closesocket(sock);
 296 out:
 297     kill(getpid(), SIGTERM);
 298     return (void *) EXIT_FAILURE;
 299 }
 300
 301 static int nbd_can_accept(void)
 302 {
 303     return nb_fds < shared;
 304 }
 305
 306 static void nbd_export_closed(NBDExport *exp)
 307 {
 308     assert(state == TERMINATING);
 309     state = TERMINATED;
 310 }
 311
 312 static void nbd_update_server_fd_handler(int fd);
 313
 314 static void nbd_client_closed(NBDClient *client)
 315 {
 316     nb_fds--;
 317     if (nb_fds == 0 && !persistent && state == RUNNING) {
 318         state = TERMINATE;
 319     }
 320     nbd_update_server_fd_handler(server_fd);
 321     nbd_client_put(client);
 322 }
 323
 324 static void nbd_accept(void *opaque)
 325 {
 326     struct sockaddr_in addr;
 327     socklen_t addr_len = sizeof(addr);
 328
 329     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
 330     if (fd < 0) {
 331         perror("accept");
 332         return;
 333     }
 334
 335     if (state >= TERMINATE) {
 336         close(fd);
 337         return;
 338     }
 339
 340     if (nbd_client_new(exp, fd, nbd_client_closed)) {
 341         nb_fds++;
 342         nbd_update_server_fd_handler(server_fd);
 343     } else {
 344         shutdown(fd, 2);
 345         close(fd);
 346     }
 347 }
 348
 349 static void nbd_update_server_fd_handler(int fd)
 350 {
 351     if (nbd_can_accept()) {
 352         qemu_set_fd_handler(fd, nbd_accept, NULL, (void *)(uintptr_t)fd);
 353     } else {
 354         qemu_set_fd_handler(fd, NULL, NULL, NULL);
 355     }
 356 }
 357
 358
 359 static SocketAddress *nbd_build_socket_address(const char *sockpath,
 360                                                const char *bindto,
 361                                                const char *port)
 362 {
 363     SocketAddress *saddr;
 364
 365     saddr = g_new0(SocketAddress, 1);
 366     if (sockpath) {
 367         saddr->kind = SOCKET_ADDRESS_KIND_UNIX;
 368         saddr->q_unix = g_new0(UnixSocketAddress, 1);
 369         saddr->q_unix->path = g_strdup(sockpath);
 370     } else {
 371         saddr->kind = SOCKET_ADDRESS_KIND_INET;
 372         saddr->inet = g_new0(InetSocketAddress, 1);
 373         saddr->inet->host = g_strdup(bindto);
 374         if (port) {
 375             saddr->inet->port = g_strdup(port);
 376         } else  {
 377             saddr->inet->port = g_strdup_printf("%d", NBD_DEFAULT_PORT);
 378         }
 379     }
 380
 381     return saddr;
 382 }
 383
 384
 385 int main(int argc, char **argv)
 386 {
 387     BlockBackend *blk;
 388     BlockDriverState *bs;
 389     off_t dev_offset = 0;
 390     uint32_t nbdflags = 0;
 391     bool disconnect = false;
 392     const char *bindto = "0.0.0.0";
 393     const char *port = NULL;
 394     char *sockpath = NULL;
 395     char *device = NULL;
 396     off_t fd_size;
 397     QemuOpts *sn_opts = NULL;
 398     const char *sn_id_or_name = NULL;
 399     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:";
 400     struct option lopt[] = {
 401         { "help", 0, NULL, 'h' },
 402         { "version", 0, NULL, 'V' },
 403         { "bind", 1, NULL, 'b' },
 404         { "port", 1, NULL, 'p' },
 405         { "socket", 1, NULL, 'k' },
 406         { "offset", 1, NULL, 'o' },
 407         { "read-only", 0, NULL, 'r' },
 408         { "partition", 1, NULL, 'P' },
 409         { "connect", 1, NULL, 'c' },
 410         { "disconnect", 0, NULL, 'd' },
 411         { "snapshot", 0, NULL, 's' },
 412         { "load-snapshot", 1, NULL, 'l' },
 413         { "nocache", 0, NULL, 'n' },
 414         { "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
 415 #ifdef CONFIG_LINUX_AIO
 416         { "aio", 1, NULL, QEMU_NBD_OPT_AIO },
 417 #endif
 418         { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
 419         { "detect-zeroes", 1, NULL, QEMU_NBD_OPT_DETECT_ZEROES },
 420         { "shared", 1, NULL, 'e' },
 421         { "format", 1, NULL, 'f' },
 422         { "persistent", 0, NULL, 't' },
 423         { "verbose", 0, NULL, 'v' },
 424         { NULL, 0, NULL, 0 }
 425     };
 426     int ch;
 427     int opt_ind = 0;
 428     char *end;
 429     int flags = BDRV_O_RDWR;
 430     int partition = -1;
 431     int ret = 0;
 432     int fd;
 433     bool seen_cache = false;
 434     bool seen_discard = false;
 435 #ifdef CONFIG_LINUX_AIO
 436     bool seen_aio = false;
 437 #endif
 438     pthread_t client_thread;
 439     const char *fmt = NULL;
 440     Error *local_err = NULL;
 441     BlockdevDetectZeroesOptions detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF;
 442     QDict *options = NULL;
 443
 444     /* The client thread uses SIGTERM to interrupt the server.  A signal
 445      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 446      */
 447     struct sigaction sa_sigterm;
 448     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 449     sa_sigterm.sa_handler = termsig_handler;
 450     sigaction(SIGTERM, &sa_sigterm, NULL);
 451     qemu_init_exec_dir(argv[0]);
 452
 453     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 454         switch (ch) {
 455         case 's':
 456             flags |= BDRV_O_SNAPSHOT;
 457             break;
 458         case 'n':
 459             optarg = (char *) "none";
 460             /* fallthrough */
 461         case QEMU_NBD_OPT_CACHE:
 462             if (seen_cache) {
 463                 errx(EXIT_FAILURE, "-n and --cache can only be specified once");
 464             }
 465             seen_cache = true;
 466             if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
 467                 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
 468             }
 469             break;
 470 #ifdef CONFIG_LINUX_AIO
 471         case QEMU_NBD_OPT_AIO:
 472             if (seen_aio) {
 473                 errx(EXIT_FAILURE, "--aio can only be specified once");
 474             }
 475             seen_aio = true;
 476             if (!strcmp(optarg, "native")) {
 477                 flags |= BDRV_O_NATIVE_AIO;
 478             } else if (!strcmp(optarg, "threads")) {
 479                 /* this is the default */
 480             } else {
 481                errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
 482             }
 483             break;
 484 #endif
 485         case QEMU_NBD_OPT_DISCARD:
 486             if (seen_discard) {
 487                 errx(EXIT_FAILURE, "--discard can only be specified once");
 488             }
 489             seen_discard = true;
 490             if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
 491                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
 492             }
 493             break;
 494         case QEMU_NBD_OPT_DETECT_ZEROES:
 495             detect_zeroes =
 496                 qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
 497                                 optarg,
 498                                 BLOCKDEV_DETECT_ZEROES_OPTIONS_MAX,
 499                                 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
 500                                 &local_err);
 501             if (local_err) {
 502                 errx(EXIT_FAILURE, "Failed to parse detect_zeroes mode: %s",
 503                      error_get_pretty(local_err));
 504             }
 505             if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
 506                 !(flags & BDRV_O_UNMAP)) {
 507                 errx(EXIT_FAILURE, "setting detect-zeroes to unmap is not allowed "
 508                                    "without setting discard operation to unmap");
 509             }
 510             break;
 511         case 'b':
 512             bindto = optarg;
 513             break;
 514         case 'p':
 515             port = optarg;
 516             break;
 517         case 'o':
 518                 dev_offset = strtoll (optarg, &end, 0);
 519             if (*end) {
 520                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 521             }
 522             if (dev_offset < 0) {
 523                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 524             }
 525             break;
 526         case 'l':
 527             if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
 528                 sn_opts = qemu_opts_parse_noisily(&internal_snapshot_opts,
 529                                                   optarg, false);
 530                 if (!sn_opts) {
 531                     errx(EXIT_FAILURE, "Failed in parsing snapshot param `%s'",
 532                          optarg);
 533                 }
 534             } else {
 535                 sn_id_or_name = optarg;
 536             }
 537             /* fall through */
 538         case 'r':
 539             nbdflags |= NBD_FLAG_READ_ONLY;
 540             flags &= ~BDRV_O_RDWR;
 541             break;
 542         case 'P':
 543             partition = strtol(optarg, &end, 0);
 544             if (*end) {
 545                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 546             }
 547             if (partition < 1 || partition > 8) {
 548                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 549             }
 550             break;
 551         case 'k':
 552             sockpath = optarg;
 553             if (sockpath[0] != '/') {
 554                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 555             }
 556             break;
 557         case 'd':
 558             disconnect = true;
 559             break;
 560         case 'c':
 561             device = optarg;
 562             break;
 563         case 'e':
 564             shared = strtol(optarg, &end, 0);
 565             if (*end) {
 566                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 567             }
 568             if (shared < 1) {
 569                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 570             }
 571             break;
 572         case 'f':
 573             fmt = optarg;
 574             break;
 575         case 't':
 576             persistent = 1;
 577             break;
 578         case 'v':
 579             verbose = 1;
 580             break;
 581         case 'V':
 582             version(argv[0]);
 583             exit(0);
 584             break;
 585         case 'h':
 586             usage(argv[0]);
 587             exit(0);
 588             break;
 589         case '?':
 590             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 591                  argv[0]);
 592         }
 593     }
 594
 595     if ((argc - optind) != 1) {
 596         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 597              "Try `%s --help' for more information.",
 598              argv[0]);
 599     }
 600
 601     if (disconnect) {
 602         fd = open(argv[optind], O_RDWR);
 603         if (fd < 0) {
 604             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 605         }
 606         nbd_disconnect(fd);
 607
 608         close(fd);
 609
 610         printf("%s disconnected\n", argv[optind]);
 611
 612         return 0;
 613     }
 614
 615     if (device && !verbose) {
 616         int stderr_fd[2];
 617         pid_t pid;
 618         int ret;
 619
 620         if (qemu_pipe(stderr_fd) < 0) {
 621             err(EXIT_FAILURE, "Error setting up communication pipe");
 622         }
 623
 624         /* Now daemonize, but keep a communication channel open to
 625          * print errors and exit with the proper status code.
 626          */
 627         pid = fork();
 628         if (pid < 0) {
 629             err(EXIT_FAILURE, "Failed to fork");
 630         } else if (pid == 0) {
 631             close(stderr_fd[0]);
 632             ret = qemu_daemon(1, 0);
 633
 634             /* Temporarily redirect stderr to the parent's pipe...  */
 635             dup2(stderr_fd[1], STDERR_FILENO);
 636             if (ret < 0) {
 637                 err(EXIT_FAILURE, "Failed to daemonize");
 638             }
 639
 640             /* ... close the descriptor we inherited and go on.  */
 641             close(stderr_fd[1]);
 642         } else {
 643             bool errors = false;
 644             char *buf;
 645
 646             /* In the parent.  Print error messages from the child until
 647              * it closes the pipe.
 648              */
 649             close(stderr_fd[1]);
 650             buf = g_malloc(1024);
 651             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 652                 errors = true;
 653                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 654                 if (ret < 0) {
 655                     exit(EXIT_FAILURE);
 656                 }
 657             }
 658             if (ret < 0) {
 659                 err(EXIT_FAILURE, "Cannot read from daemon");
 660             }
 661
 662             /* Usually the daemon should not print any message.
 663              * Exit with zero status in that case.
 664              */
 665             exit(errors);
 666         }
 667     }
 668
 669     if (device != NULL && sockpath == NULL) {
 670         sockpath = g_malloc(128);
 671         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 672     }
 673
 674     saddr = nbd_build_socket_address(sockpath, bindto, port);
 675
 676     if (qemu_init_main_loop(&local_err)) {
 677         error_report_err(local_err);
 678         exit(EXIT_FAILURE);
 679     }
 680     bdrv_init();
 681     atexit(bdrv_close_all);
 682
 683     if (fmt) {
 684         options = qdict_new();
 685         qdict_put(options, "driver", qstring_from_str(fmt));
 686     }
 687
 688     srcpath = argv[optind];
 689     blk = blk_new_open("hda", srcpath, NULL, options, flags, &local_err);
 690     if (!blk) {
 691         errx(EXIT_FAILURE, "Failed to blk_new_open '%s': %s", argv[optind],
 692              error_get_pretty(local_err));
 693     }
 694     bs = blk_bs(blk);
 695
 696     if (sn_opts) {
 697         ret = bdrv_snapshot_load_tmp(bs,
 698                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
 699                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
 700                                      &local_err);
 701     } else if (sn_id_or_name) {
 702         ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name,
 703                                                    &local_err);
 704     }
 705     if (ret < 0) {
 706         errno = -ret;
 707         err(EXIT_FAILURE,
 708             "Failed to load snapshot: %s",
 709             error_get_pretty(local_err));
 710     }
 711
 712     bs->detect_zeroes = detect_zeroes;
 713     fd_size = blk_getlength(blk);
 714     if (fd_size < 0) {
 715         errx(EXIT_FAILURE, "Failed to determine the image length: %s",
 716              strerror(-fd_size));
 717     }
 718
 719     if (partition != -1) {
 720         ret = find_partition(blk, partition, &dev_offset, &fd_size);
 721         if (ret < 0) {
 722             errno = -ret;
 723             err(EXIT_FAILURE, "Could not find partition %d", partition);
 724         }
 725     }
 726
 727     exp = nbd_export_new(blk, dev_offset, fd_size, nbdflags, nbd_export_closed,
 728                          &local_err);
 729     if (!exp) {
 730         errx(EXIT_FAILURE, "%s", error_get_pretty(local_err));
 731     }
 732
 733     fd = socket_listen(saddr, &local_err);
 734     if (fd < 0) {
 735         error_report_err(local_err);
 736         return 1;
 737     }
 738
 739     if (device) {
 740         int ret;
 741
 742         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 743         if (ret != 0) {
 744             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 745                  strerror(ret));
 746         }
 747     } else {
 748         /* Shut up GCC warnings.  */
 749         memset(&client_thread, 0, sizeof(client_thread));
 750     }
 751
 752     server_fd = fd;
 753     nbd_update_server_fd_handler(fd);
 754
 755     /* now when the initialization is (almost) complete, chdir("/")
 756      * to free any busy filesystems */
 757     if (chdir("/") < 0) {
 758         err(EXIT_FAILURE, "Could not chdir to root directory");
 759     }
 760
 761     state = RUNNING;
 762     do {
 763         main_loop_wait(false);
 764         if (state == TERMINATE) {
 765             state = TERMINATING;
 766             nbd_export_close(exp);
 767             nbd_export_put(exp);
 768             exp = NULL;
 769         }
 770     } while (state != TERMINATED);
 771
 772     blk_unref(blk);
 773     if (sockpath) {
 774         unlink(sockpath);
 775     }
 776
 777     qemu_opts_del(sn_opts);
 778
 779     if (device) {
 780         void *ret;
 781         pthread_join(client_thread, &ret);
 782         exit(ret != NULL);
 783     } else {
 784         exit(EXIT_SUCCESS);
 785     }
 786 }