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 "block/block.h"
  21 #include "block/nbd.h"
  22 #include "qemu/main-loop.h"
  23 #include "qemu/sockets.h"
  24 #include "qemu/error-report.h"
  25 #include "block/snapshot.h"
  26
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <getopt.h>
  30 #include <err.h>
  31 #include <sys/types.h>
  32 #include <sys/socket.h>
  33 #include <netinet/in.h>
  34 #include <netinet/tcp.h>
  35 #include <arpa/inet.h>
  36 #include <signal.h>
  37 #include <libgen.h>
  38 #include <pthread.h>
  39
  40 #define SOCKET_PATH          "/var/lock/qemu-nbd-%s"
  41 #define QEMU_NBD_OPT_CACHE   1
  42 #define QEMU_NBD_OPT_AIO     2
  43 #define QEMU_NBD_OPT_DISCARD 3
  44
  45 static NBDExport *exp;
  46 static int verbose;
  47 static char *srcpath;
  48 static char *sockpath;
  49 static int persistent = 0;
  50 static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
  51 static int shared = 1;
  52 static int nb_fds;
  53
  54 static void usage(const char *name)
  55 {
  56     (printf) (
  57 "Usage: %s [OPTIONS] FILE\n"
  58 "QEMU Disk Network Block Device Server\n"
  59 "\n"
  60 "  -h, --help           display this help and exit\n"
  61 "  -V, --version        output version information and exit\n"
  62 "\n"
  63 "Connection properties:\n"
  64 "  -p, --port=PORT      port to listen on (default `%d')\n"
  65 "  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
  66 "  -k, --socket=PATH    path to the unix socket\n"
  67 "                       (default '"SOCKET_PATH"')\n"
  68 "  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
  69 "  -t, --persistent     don't exit on the last connection\n"
  70 "  -v, --verbose        display extra debugging information\n"
  71 "\n"
  72 "Exposing part of the image:\n"
  73 "  -o, --offset=OFFSET  offset into the image\n"
  74 "  -P, --partition=NUM  only expose partition NUM\n"
  75 "\n"
  76 #ifdef __linux__
  77 "Kernel NBD client support:\n"
  78 "  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
  79 "  -d, --disconnect     disconnect the specified device\n"
  80 "\n"
  81 #endif
  82 "\n"
  83 "Block device options:\n"
  84 "  -f, --format=FORMAT  set image format (raw, qcow2, ...)\n"
  85 "  -r, --read-only      export read-only\n"
  86 "  -s, --snapshot       use FILE as an external snapshot, create a temporary\n"
  87 "                       file with backing_file=FILE, redirect the write to\n"
  88 "                       the temporary one\n"
  89 "  -l, --load-snapshot=SNAPSHOT_PARAM\n"
  90 "                       load an internal snapshot inside FILE and export it\n"
  91 "                       as an read-only device, SNAPSHOT_PARAM format is\n"
  92 "                       'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
  93 "                       '[ID_OR_NAME]'\n"
  94 "  -n, --nocache        disable host cache\n"
  95 "      --cache=MODE     set cache mode (none, writeback, ...)\n"
  96 #ifdef CONFIG_LINUX_AIO
  97 "      --aio=MODE       set AIO mode (native or threads)\n"
  98 #endif
  99 "\n"
 100 "Report bugs to <qemu-devel@nongnu.org>\n"
 101     , name, NBD_DEFAULT_PORT, "DEVICE");
 102 }
 103
 104 static void version(const char *name)
 105 {
 106     printf(
 107 "%s version 0.0.1\n"
 108 "Written by Anthony Liguori.\n"
 109 "\n"
 110 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
 111 "This is free software; see the source for copying conditions.  There is NO\n"
 112 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 113     , name);
 114 }
 115
 116 struct partition_record
 117 {
 118     uint8_t bootable;
 119     uint8_t start_head;
 120     uint32_t start_cylinder;
 121     uint8_t start_sector;
 122     uint8_t system;
 123     uint8_t end_head;
 124     uint8_t end_cylinder;
 125     uint8_t end_sector;
 126     uint32_t start_sector_abs;
 127     uint32_t nb_sectors_abs;
 128 };
 129
 130 static void read_partition(uint8_t *p, struct partition_record *r)
 131 {
 132     r->bootable = p[0];
 133     r->start_head = p[1];
 134     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
 135     r->start_sector = p[2] & 0x3f;
 136     r->system = p[4];
 137     r->end_head = p[5];
 138     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 139     r->end_sector = p[6] & 0x3f;
 140     r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 141     r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 142 }
 143
 144 static int find_partition(BlockDriverState *bs, int partition,
 145                           off_t *offset, off_t *size)
 146 {
 147     struct partition_record mbr[4];
 148     uint8_t data[512];
 149     int i;
 150     int ext_partnum = 4;
 151     int ret;
 152
 153     if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 154         errno = -ret;
 155         err(EXIT_FAILURE, "error while reading");
 156     }
 157
 158     if (data[510] != 0x55 || data[511] != 0xaa) {
 159         return -EINVAL;
 160     }
 161
 162     for (i = 0; i < 4; i++) {
 163         read_partition(&data[446 + 16 * i], &mbr[i]);
 164
 165         if (!mbr[i].nb_sectors_abs)
 166             continue;
 167
 168         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 169             struct partition_record ext[4];
 170             uint8_t data1[512];
 171             int j;
 172
 173             if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 174                 errno = -ret;
 175                 err(EXIT_FAILURE, "error while reading");
 176             }
 177
 178             for (j = 0; j < 4; j++) {
 179                 read_partition(&data1[446 + 16 * j], &ext[j]);
 180                 if (!ext[j].nb_sectors_abs)
 181                     continue;
 182
 183                 if ((ext_partnum + j + 1) == partition) {
 184                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 185                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 186                     return 0;
 187                 }
 188             }
 189             ext_partnum += 4;
 190         } else if ((i + 1) == partition) {
 191             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 192             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 193             return 0;
 194         }
 195     }
 196
 197     return -ENOENT;
 198 }
 199
 200 static void termsig_handler(int signum)
 201 {
 202     state = TERMINATE;
 203     qemu_notify_event();
 204 }
 205
 206 static void combine_addr(char *buf, size_t len, const char* address,
 207                          uint16_t port)
 208 {
 209     /* If the address-part contains a colon, it's an IPv6 IP so needs [] */
 210     if (strstr(address, ":")) {
 211         snprintf(buf, len, "[%s]:%u", address, port);
 212     } else {
 213         snprintf(buf, len, "%s:%u", address, port);
 214     }
 215 }
 216
 217 static int tcp_socket_incoming(const char *address, uint16_t port)
 218 {
 219     char address_and_port[128];
 220     Error *local_err = NULL;
 221
 222     combine_addr(address_and_port, 128, address, port);
 223     int fd = inet_listen(address_and_port, NULL, 0, SOCK_STREAM, 0, &local_err);
 224
 225     if (local_err != NULL) {
 226         qerror_report_err(local_err);
 227         error_free(local_err);
 228     }
 229     return fd;
 230 }
 231
 232 static int unix_socket_incoming(const char *path)
 233 {
 234     Error *local_err = NULL;
 235     int fd = unix_listen(path, NULL, 0, &local_err);
 236
 237     if (local_err != NULL) {
 238         qerror_report_err(local_err);
 239         error_free(local_err);
 240     }
 241     return fd;
 242 }
 243
 244 static int unix_socket_outgoing(const char *path)
 245 {
 246     Error *local_err = NULL;
 247     int fd = unix_connect(path, &local_err);
 248
 249     if (local_err != NULL) {
 250         qerror_report_err(local_err);
 251         error_free(local_err);
 252     }
 253     return fd;
 254 }
 255
 256 static void *show_parts(void *arg)
 257 {
 258     char *device = arg;
 259     int nbd;
 260
 261     /* linux just needs an open() to trigger
 262      * the partition table update
 263      * but remember to load the module with max_part != 0 :
 264      *     modprobe nbd max_part=63
 265      */
 266     nbd = open(device, O_RDWR);
 267     if (nbd >= 0) {
 268         close(nbd);
 269     }
 270     return NULL;
 271 }
 272
 273 static void *nbd_client_thread(void *arg)
 274 {
 275     char *device = arg;
 276     off_t size;
 277     size_t blocksize;
 278     uint32_t nbdflags;
 279     int fd, sock;
 280     int ret;
 281     pthread_t show_parts_thread;
 282
 283     sock = unix_socket_outgoing(sockpath);
 284     if (sock < 0) {
 285         goto out;
 286     }
 287
 288     ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 289                                 &size, &blocksize);
 290     if (ret < 0) {
 291         goto out_socket;
 292     }
 293
 294     fd = open(device, O_RDWR);
 295     if (fd < 0) {
 296         /* Linux-only, we can use %m in printf.  */
 297         fprintf(stderr, "Failed to open %s: %m", device);
 298         goto out_socket;
 299     }
 300
 301     ret = nbd_init(fd, sock, nbdflags, size, blocksize);
 302     if (ret < 0) {
 303         goto out_fd;
 304     }
 305
 306     /* update partition table */
 307     pthread_create(&show_parts_thread, NULL, show_parts, device);
 308
 309     if (verbose) {
 310         fprintf(stderr, "NBD device %s is now connected to %s\n",
 311                 device, srcpath);
 312     } else {
 313         /* Close stderr so that the qemu-nbd process exits.  */
 314         dup2(STDOUT_FILENO, STDERR_FILENO);
 315     }
 316
 317     ret = nbd_client(fd);
 318     if (ret) {
 319         goto out_fd;
 320     }
 321     close(fd);
 322     kill(getpid(), SIGTERM);
 323     return (void *) EXIT_SUCCESS;
 324
 325 out_fd:
 326     close(fd);
 327 out_socket:
 328     closesocket(sock);
 329 out:
 330     kill(getpid(), SIGTERM);
 331     return (void *) EXIT_FAILURE;
 332 }
 333
 334 static int nbd_can_accept(void *opaque)
 335 {
 336     return nb_fds < shared;
 337 }
 338
 339 static void nbd_export_closed(NBDExport *exp)
 340 {
 341     assert(state == TERMINATING);
 342     state = TERMINATED;
 343 }
 344
 345 static void nbd_client_closed(NBDClient *client)
 346 {
 347     nb_fds--;
 348     if (nb_fds == 0 && !persistent && state == RUNNING) {
 349         state = TERMINATE;
 350     }
 351     qemu_notify_event();
 352     nbd_client_put(client);
 353 }
 354
 355 static void nbd_accept(void *opaque)
 356 {
 357     int server_fd = (uintptr_t) opaque;
 358     struct sockaddr_in addr;
 359     socklen_t addr_len = sizeof(addr);
 360
 361     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
 362     if (fd < 0) {
 363         perror("accept");
 364         return;
 365     }
 366
 367     if (state >= TERMINATE) {
 368         close(fd);
 369         return;
 370     }
 371
 372     if (fd >= 0 && nbd_client_new(exp, fd, nbd_client_closed)) {
 373         nb_fds++;
 374     }
 375 }
 376
 377 int main(int argc, char **argv)
 378 {
 379     BlockDriverState *bs;
 380     BlockDriver *drv;
 381     off_t dev_offset = 0;
 382     uint32_t nbdflags = 0;
 383     bool disconnect = false;
 384     const char *bindto = "0.0.0.0";
 385     char *device = NULL;
 386     int port = NBD_DEFAULT_PORT;
 387     off_t fd_size;
 388     QemuOpts *sn_opts = NULL;
 389     const char *sn_id_or_name = NULL;
 390     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:";
 391     struct option lopt[] = {
 392         { "help", 0, NULL, 'h' },
 393         { "version", 0, NULL, 'V' },
 394         { "bind", 1, NULL, 'b' },
 395         { "port", 1, NULL, 'p' },
 396         { "socket", 1, NULL, 'k' },
 397         { "offset", 1, NULL, 'o' },
 398         { "read-only", 0, NULL, 'r' },
 399         { "partition", 1, NULL, 'P' },
 400         { "connect", 1, NULL, 'c' },
 401         { "disconnect", 0, NULL, 'd' },
 402         { "snapshot", 0, NULL, 's' },
 403         { "load-snapshot", 1, NULL, 'l' },
 404         { "nocache", 0, NULL, 'n' },
 405         { "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
 406 #ifdef CONFIG_LINUX_AIO
 407         { "aio", 1, NULL, QEMU_NBD_OPT_AIO },
 408 #endif
 409         { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
 410         { "shared", 1, NULL, 'e' },
 411         { "format", 1, NULL, 'f' },
 412         { "persistent", 0, NULL, 't' },
 413         { "verbose", 0, NULL, 'v' },
 414         { NULL, 0, NULL, 0 }
 415     };
 416     int ch;
 417     int opt_ind = 0;
 418     int li;
 419     char *end;
 420     int flags = BDRV_O_RDWR;
 421     int partition = -1;
 422     int ret;
 423     int fd;
 424     bool seen_cache = false;
 425     bool seen_discard = false;
 426 #ifdef CONFIG_LINUX_AIO
 427     bool seen_aio = false;
 428 #endif
 429     pthread_t client_thread;
 430     const char *fmt = NULL;
 431     Error *local_err = NULL;
 432
 433     /* The client thread uses SIGTERM to interrupt the server.  A signal
 434      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 435      */
 436     struct sigaction sa_sigterm;
 437     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 438     sa_sigterm.sa_handler = termsig_handler;
 439     sigaction(SIGTERM, &sa_sigterm, NULL);
 440     qemu_init_exec_dir(argv[0]);
 441
 442     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 443         switch (ch) {
 444         case 's':
 445             flags |= BDRV_O_SNAPSHOT;
 446             break;
 447         case 'n':
 448             optarg = (char *) "none";
 449             /* fallthrough */
 450         case QEMU_NBD_OPT_CACHE:
 451             if (seen_cache) {
 452                 errx(EXIT_FAILURE, "-n and --cache can only be specified once");
 453             }
 454             seen_cache = true;
 455             if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
 456                 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
 457             }
 458             break;
 459 #ifdef CONFIG_LINUX_AIO
 460         case QEMU_NBD_OPT_AIO:
 461             if (seen_aio) {
 462                 errx(EXIT_FAILURE, "--aio can only be specified once");
 463             }
 464             seen_aio = true;
 465             if (!strcmp(optarg, "native")) {
 466                 flags |= BDRV_O_NATIVE_AIO;
 467             } else if (!strcmp(optarg, "threads")) {
 468                 /* this is the default */
 469             } else {
 470                errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
 471             }
 472             break;
 473 #endif
 474         case QEMU_NBD_OPT_DISCARD:
 475             if (seen_discard) {
 476                 errx(EXIT_FAILURE, "--discard can only be specified once");
 477             }
 478             seen_discard = true;
 479             if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
 480                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
 481             }
 482             break;
 483         case 'b':
 484             bindto = optarg;
 485             break;
 486         case 'p':
 487             li = strtol(optarg, &end, 0);
 488             if (*end) {
 489                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 490             }
 491             if (li < 1 || li > 65535) {
 492                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 493             }
 494             port = (uint16_t)li;
 495             break;
 496         case 'o':
 497                 dev_offset = strtoll (optarg, &end, 0);
 498             if (*end) {
 499                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 500             }
 501             if (dev_offset < 0) {
 502                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 503             }
 504             break;
 505         case 'l':
 506             if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
 507                 sn_opts = qemu_opts_parse(&internal_snapshot_opts, optarg, 0);
 508                 if (!sn_opts) {
 509                     errx(EXIT_FAILURE, "Failed in parsing snapshot param `%s'",
 510                          optarg);
 511                 }
 512             } else {
 513                 sn_id_or_name = optarg;
 514             }
 515             /* fall through */
 516         case 'r':
 517             nbdflags |= NBD_FLAG_READ_ONLY;
 518             flags &= ~BDRV_O_RDWR;
 519             break;
 520         case 'P':
 521             partition = strtol(optarg, &end, 0);
 522             if (*end)
 523                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 524             if (partition < 1 || partition > 8)
 525                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 526             break;
 527         case 'k':
 528             sockpath = optarg;
 529             if (sockpath[0] != '/')
 530                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 531             break;
 532         case 'd':
 533             disconnect = true;
 534             break;
 535         case 'c':
 536             device = optarg;
 537             break;
 538         case 'e':
 539             shared = strtol(optarg, &end, 0);
 540             if (*end) {
 541                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 542             }
 543             if (shared < 1) {
 544                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 545             }
 546             break;
 547         case 'f':
 548             fmt = optarg;
 549             break;
 550         case 't':
 551             persistent = 1;
 552             break;
 553         case 'v':
 554             verbose = 1;
 555             break;
 556         case 'V':
 557             version(argv[0]);
 558             exit(0);
 559             break;
 560         case 'h':
 561             usage(argv[0]);
 562             exit(0);
 563             break;
 564         case '?':
 565             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 566                  argv[0]);
 567         }
 568     }
 569
 570     if ((argc - optind) != 1) {
 571         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 572              "Try `%s --help' for more information.",
 573              argv[0]);
 574     }
 575
 576     if (disconnect) {
 577         fd = open(argv[optind], O_RDWR);
 578         if (fd < 0) {
 579             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 580         }
 581         nbd_disconnect(fd);
 582
 583         close(fd);
 584
 585         printf("%s disconnected\n", argv[optind]);
 586
 587         return 0;
 588     }
 589
 590     if (device && !verbose) {
 591         int stderr_fd[2];
 592         pid_t pid;
 593         int ret;
 594
 595         if (qemu_pipe(stderr_fd) < 0) {
 596             err(EXIT_FAILURE, "Error setting up communication pipe");
 597         }
 598
 599         /* Now daemonize, but keep a communication channel open to
 600          * print errors and exit with the proper status code.
 601          */
 602         pid = fork();
 603         if (pid == 0) {
 604             close(stderr_fd[0]);
 605             ret = qemu_daemon(1, 0);
 606
 607             /* Temporarily redirect stderr to the parent's pipe...  */
 608             dup2(stderr_fd[1], STDERR_FILENO);
 609             if (ret < 0) {
 610                 err(EXIT_FAILURE, "Failed to daemonize");
 611             }
 612
 613             /* ... close the descriptor we inherited and go on.  */
 614             close(stderr_fd[1]);
 615         } else {
 616             bool errors = false;
 617             char *buf;
 618
 619             /* In the parent.  Print error messages from the child until
 620              * it closes the pipe.
 621              */
 622             close(stderr_fd[1]);
 623             buf = g_malloc(1024);
 624             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 625                 errors = true;
 626                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 627                 if (ret < 0) {
 628                     exit(EXIT_FAILURE);
 629                 }
 630             }
 631             if (ret < 0) {
 632                 err(EXIT_FAILURE, "Cannot read from daemon");
 633             }
 634
 635             /* Usually the daemon should not print any message.
 636              * Exit with zero status in that case.
 637              */
 638             exit(errors);
 639         }
 640     }
 641
 642     if (device != NULL && sockpath == NULL) {
 643         sockpath = g_malloc(128);
 644         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 645     }
 646
 647     qemu_init_main_loop();
 648     bdrv_init();
 649     atexit(bdrv_close_all);
 650
 651     if (fmt) {
 652         drv = bdrv_find_format(fmt);
 653         if (!drv) {
 654             errx(EXIT_FAILURE, "Unknown file format '%s'", fmt);
 655         }
 656     } else {
 657         drv = NULL;
 658     }
 659
 660     bs = bdrv_new("hda", &error_abort);
 661
 662     srcpath = argv[optind];
 663     ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);
 664     if (ret < 0) {
 665         errno = -ret;
 666         err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind],
 667             error_get_pretty(local_err));
 668     }
 669
 670     if (sn_opts) {
 671         ret = bdrv_snapshot_load_tmp(bs,
 672                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
 673                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
 674                                      &local_err);
 675     } else if (sn_id_or_name) {
 676         ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name,
 677                                                    &local_err);
 678     }
 679     if (ret < 0) {
 680         errno = -ret;
 681         err(EXIT_FAILURE,
 682             "Failed to load snapshot: %s",
 683             error_get_pretty(local_err));
 684     }
 685
 686     fd_size = bdrv_getlength(bs);
 687
 688     if (partition != -1) {
 689         ret = find_partition(bs, partition, &dev_offset, &fd_size);
 690         if (ret < 0) {
 691             errno = -ret;
 692             err(EXIT_FAILURE, "Could not find partition %d", partition);
 693         }
 694     }
 695
 696     exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed);
 697
 698     if (sockpath) {
 699         fd = unix_socket_incoming(sockpath);
 700     } else {
 701         fd = tcp_socket_incoming(bindto, port);
 702     }
 703
 704     if (fd < 0) {
 705         return 1;
 706     }
 707
 708     if (device) {
 709         int ret;
 710
 711         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 712         if (ret != 0) {
 713             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 714                  strerror(ret));
 715         }
 716     } else {
 717         /* Shut up GCC warnings.  */
 718         memset(&client_thread, 0, sizeof(client_thread));
 719     }
 720
 721     qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
 722                          (void *)(uintptr_t)fd);
 723
 724     /* now when the initialization is (almost) complete, chdir("/")
 725      * to free any busy filesystems */
 726     if (chdir("/") < 0) {
 727         err(EXIT_FAILURE, "Could not chdir to root directory");
 728     }
 729
 730     state = RUNNING;
 731     do {
 732         main_loop_wait(false);
 733         if (state == TERMINATE) {
 734             state = TERMINATING;
 735             nbd_export_close(exp);
 736             nbd_export_put(exp);
 737             exp = NULL;
 738         }
 739     } while (state != TERMINATED);
 740
 741     bdrv_close(bs);
 742     if (sockpath) {
 743         unlink(sockpath);
 744     }
 745
 746     if (sn_opts) {
 747         qemu_opts_del(sn_opts);
 748     }
 749
 750     if (device) {
 751         void *ret;
 752         pthread_join(client_thread, &ret);
 753         exit(ret != NULL);
 754     } else {
 755         exit(EXIT_SUCCESS);
 756     }
 757 }