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/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
  29 #include <stdarg.h>
  30 #include <stdio.h>
  31 #include <getopt.h>
  32 #include <err.h>
  33 #include <sys/types.h>
  34 #include <sys/socket.h>
  35 #include <netinet/in.h>
  36 #include <netinet/tcp.h>
  37 #include <arpa/inet.h>
  38 #include <signal.h>
  39 #include <libgen.h>
  40 #include <pthread.h>
  41
  42 #define SOCKET_PATH                "/var/lock/qemu-nbd-%s"
  43 #define QEMU_NBD_OPT_CACHE         1
  44 #define QEMU_NBD_OPT_AIO           2
  45 #define QEMU_NBD_OPT_DISCARD       3
  46 #define QEMU_NBD_OPT_DETECT_ZEROES 4
  47
  48 static NBDExport *exp;
  49 static int verbose;
  50 static char *srcpath;
  51 static char *sockpath;
  52 static int persistent = 0;
  53 static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
  54 static int shared = 1;
  55 static int nb_fds;
  56
  57 static void usage(const char *name)
  58 {
  59     (printf) (
  60 "Usage: %s [OPTIONS] FILE\n"
  61 "QEMU Disk Network Block Device Server\n"
  62 "\n"
  63 "  -h, --help                display this help and exit\n"
  64 "  -V, --version             output version information and exit\n"
  65 "\n"
  66 "Connection properties:\n"
  67 "  -p, --port=PORT           port to listen on (default `%d')\n"
  68 "  -b, --bind=IFACE          interface to bind to (default `0.0.0.0')\n"
  69 "  -k, --socket=PATH         path to the unix socket\n"
  70 "                            (default '"SOCKET_PATH"')\n"
  71 "  -e, --shared=NUM          device can be shared by NUM clients (default '1')\n"
  72 "  -t, --persistent          don't exit on the last connection\n"
  73 "  -v, --verbose             display extra debugging information\n"
  74 "\n"
  75 "Exposing part of the image:\n"
  76 "  -o, --offset=OFFSET       offset into the image\n"
  77 "  -P, --partition=NUM       only expose partition NUM\n"
  78 "\n"
  79 #ifdef __linux__
  80 "Kernel NBD client support:\n"
  81 "  -c, --connect=DEV         connect FILE to the local NBD device DEV\n"
  82 "  -d, --disconnect          disconnect the specified device\n"
  83 "\n"
  84 #endif
  85 "\n"
  86 "Block device options:\n"
  87 "  -f, --format=FORMAT       set image format (raw, qcow2, ...)\n"
  88 "  -r, --read-only           export read-only\n"
  89 "  -s, --snapshot            use FILE as an external snapshot, create a temporary\n"
  90 "                            file with backing_file=FILE, redirect the write to\n"
  91 "                            the temporary one\n"
  92 "  -l, --load-snapshot=SNAPSHOT_PARAM\n"
  93 "                            load an internal snapshot inside FILE and export it\n"
  94 "                            as an read-only device, SNAPSHOT_PARAM format is\n"
  95 "                            'snapshot.id=[ID],snapshot.name=[NAME]', or\n"
  96 "                            '[ID_OR_NAME]'\n"
  97 "  -n, --nocache             disable host cache\n"
  98 "      --cache=MODE          set cache mode (none, writeback, ...)\n"
  99 #ifdef CONFIG_LINUX_AIO
 100 "      --aio=MODE            set AIO mode (native or threads)\n"
 101 #endif
 102 "      --discard=MODE        set discard mode (ignore, unmap)\n"
 103 "      --detect-zeroes=MODE  set detect-zeroes mode (off, on, discard)\n"
 104 "\n"
 105 "Report bugs to <qemu-devel@nongnu.org>\n"
 106     , name, NBD_DEFAULT_PORT, "DEVICE");
 107 }
 108
 109 static void version(const char *name)
 110 {
 111     printf(
 112 "%s version 0.0.1\n"
 113 "Written by Anthony Liguori.\n"
 114 "\n"
 115 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
 116 "This is free software; see the source for copying conditions.  There is NO\n"
 117 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 118     , name);
 119 }
 120
 121 struct partition_record
 122 {
 123     uint8_t bootable;
 124     uint8_t start_head;
 125     uint32_t start_cylinder;
 126     uint8_t start_sector;
 127     uint8_t system;
 128     uint8_t end_head;
 129     uint8_t end_cylinder;
 130     uint8_t end_sector;
 131     uint32_t start_sector_abs;
 132     uint32_t nb_sectors_abs;
 133 };
 134
 135 static void read_partition(uint8_t *p, struct partition_record *r)
 136 {
 137     r->bootable = p[0];
 138     r->start_head = p[1];
 139     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
 140     r->start_sector = p[2] & 0x3f;
 141     r->system = p[4];
 142     r->end_head = p[5];
 143     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 144     r->end_sector = p[6] & 0x3f;
 145     r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 146     r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 147 }
 148
 149 static int find_partition(BlockDriverState *bs, int partition,
 150                           off_t *offset, off_t *size)
 151 {
 152     struct partition_record mbr[4];
 153     uint8_t data[512];
 154     int i;
 155     int ext_partnum = 4;
 156     int ret;
 157
 158     if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 159         errno = -ret;
 160         err(EXIT_FAILURE, "error while reading");
 161     }
 162
 163     if (data[510] != 0x55 || data[511] != 0xaa) {
 164         return -EINVAL;
 165     }
 166
 167     for (i = 0; i < 4; i++) {
 168         read_partition(&data[446 + 16 * i], &mbr[i]);
 169
 170         if (!mbr[i].nb_sectors_abs)
 171             continue;
 172
 173         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 174             struct partition_record ext[4];
 175             uint8_t data1[512];
 176             int j;
 177
 178             if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 179                 errno = -ret;
 180                 err(EXIT_FAILURE, "error while reading");
 181             }
 182
 183             for (j = 0; j < 4; j++) {
 184                 read_partition(&data1[446 + 16 * j], &ext[j]);
 185                 if (!ext[j].nb_sectors_abs)
 186                     continue;
 187
 188                 if ((ext_partnum + j + 1) == partition) {
 189                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 190                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 191                     return 0;
 192                 }
 193             }
 194             ext_partnum += 4;
 195         } else if ((i + 1) == partition) {
 196             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 197             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 198             return 0;
 199         }
 200     }
 201
 202     return -ENOENT;
 203 }
 204
 205 static void termsig_handler(int signum)
 206 {
 207     state = TERMINATE;
 208     qemu_notify_event();
 209 }
 210
 211 static void combine_addr(char *buf, size_t len, const char* address,
 212                          uint16_t port)
 213 {
 214     /* If the address-part contains a colon, it's an IPv6 IP so needs [] */
 215     if (strstr(address, ":")) {
 216         snprintf(buf, len, "[%s]:%u", address, port);
 217     } else {
 218         snprintf(buf, len, "%s:%u", address, port);
 219     }
 220 }
 221
 222 static int tcp_socket_incoming(const char *address, uint16_t port)
 223 {
 224     char address_and_port[128];
 225     Error *local_err = NULL;
 226
 227     combine_addr(address_and_port, 128, address, port);
 228     int fd = inet_listen(address_and_port, NULL, 0, SOCK_STREAM, 0, &local_err);
 229
 230     if (local_err != NULL) {
 231         error_report("%s", error_get_pretty(local_err));
 232         error_free(local_err);
 233     }
 234     return fd;
 235 }
 236
 237 static int unix_socket_incoming(const char *path)
 238 {
 239     Error *local_err = NULL;
 240     int fd = unix_listen(path, NULL, 0, &local_err);
 241
 242     if (local_err != NULL) {
 243         error_report("%s", error_get_pretty(local_err));
 244         error_free(local_err);
 245     }
 246     return fd;
 247 }
 248
 249 static int unix_socket_outgoing(const char *path)
 250 {
 251     Error *local_err = NULL;
 252     int fd = unix_connect(path, &local_err);
 253
 254     if (local_err != NULL) {
 255         error_report("%s", error_get_pretty(local_err));
 256         error_free(local_err);
 257     }
 258     return fd;
 259 }
 260
 261 static void *show_parts(void *arg)
 262 {
 263     char *device = arg;
 264     int nbd;
 265
 266     /* linux just needs an open() to trigger
 267      * the partition table update
 268      * but remember to load the module with max_part != 0 :
 269      *     modprobe nbd max_part=63
 270      */
 271     nbd = open(device, O_RDWR);
 272     if (nbd >= 0) {
 273         close(nbd);
 274     }
 275     return NULL;
 276 }
 277
 278 static void *nbd_client_thread(void *arg)
 279 {
 280     char *device = arg;
 281     off_t size;
 282     size_t blocksize;
 283     uint32_t nbdflags;
 284     int fd, sock;
 285     int ret;
 286     pthread_t show_parts_thread;
 287
 288     sock = unix_socket_outgoing(sockpath);
 289     if (sock < 0) {
 290         goto out;
 291     }
 292
 293     ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 294                                 &size, &blocksize);
 295     if (ret < 0) {
 296         goto out_socket;
 297     }
 298
 299     fd = open(device, O_RDWR);
 300     if (fd < 0) {
 301         /* Linux-only, we can use %m in printf.  */
 302         fprintf(stderr, "Failed to open %s: %m\n", device);
 303         goto out_socket;
 304     }
 305
 306     ret = nbd_init(fd, sock, nbdflags, size, blocksize);
 307     if (ret < 0) {
 308         goto out_fd;
 309     }
 310
 311     /* update partition table */
 312     pthread_create(&show_parts_thread, NULL, show_parts, device);
 313
 314     if (verbose) {
 315         fprintf(stderr, "NBD device %s is now connected to %s\n",
 316                 device, srcpath);
 317     } else {
 318         /* Close stderr so that the qemu-nbd process exits.  */
 319         dup2(STDOUT_FILENO, STDERR_FILENO);
 320     }
 321
 322     ret = nbd_client(fd);
 323     if (ret) {
 324         goto out_fd;
 325     }
 326     close(fd);
 327     kill(getpid(), SIGTERM);
 328     return (void *) EXIT_SUCCESS;
 329
 330 out_fd:
 331     close(fd);
 332 out_socket:
 333     closesocket(sock);
 334 out:
 335     kill(getpid(), SIGTERM);
 336     return (void *) EXIT_FAILURE;
 337 }
 338
 339 static int nbd_can_accept(void *opaque)
 340 {
 341     return nb_fds < shared;
 342 }
 343
 344 static void nbd_export_closed(NBDExport *exp)
 345 {
 346     assert(state == TERMINATING);
 347     state = TERMINATED;
 348 }
 349
 350 static void nbd_client_closed(NBDClient *client)
 351 {
 352     nb_fds--;
 353     if (nb_fds == 0 && !persistent && state == RUNNING) {
 354         state = TERMINATE;
 355     }
 356     qemu_notify_event();
 357     nbd_client_put(client);
 358 }
 359
 360 static void nbd_accept(void *opaque)
 361 {
 362     int server_fd = (uintptr_t) opaque;
 363     struct sockaddr_in addr;
 364     socklen_t addr_len = sizeof(addr);
 365
 366     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
 367     if (fd < 0) {
 368         perror("accept");
 369         return;
 370     }
 371
 372     if (state >= TERMINATE) {
 373         close(fd);
 374         return;
 375     }
 376
 377     if (nbd_client_new(exp, fd, nbd_client_closed)) {
 378         nb_fds++;
 379     } else {
 380         shutdown(fd, 2);
 381         close(fd);
 382     }
 383 }
 384
 385 int main(int argc, char **argv)
 386 {
 387     BlockDriverState *bs;
 388     BlockDriver *drv;
 389     off_t dev_offset = 0;
 390     uint32_t nbdflags = 0;
 391     bool disconnect = false;
 392     const char *bindto = "0.0.0.0";
 393     char *device = NULL;
 394     int port = NBD_DEFAULT_PORT;
 395     off_t fd_size;
 396     QemuOpts *sn_opts = NULL;
 397     const char *sn_id_or_name = NULL;
 398     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:";
 399     struct option lopt[] = {
 400         { "help", 0, NULL, 'h' },
 401         { "version", 0, NULL, 'V' },
 402         { "bind", 1, NULL, 'b' },
 403         { "port", 1, NULL, 'p' },
 404         { "socket", 1, NULL, 'k' },
 405         { "offset", 1, NULL, 'o' },
 406         { "read-only", 0, NULL, 'r' },
 407         { "partition", 1, NULL, 'P' },
 408         { "connect", 1, NULL, 'c' },
 409         { "disconnect", 0, NULL, 'd' },
 410         { "snapshot", 0, NULL, 's' },
 411         { "load-snapshot", 1, NULL, 'l' },
 412         { "nocache", 0, NULL, 'n' },
 413         { "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
 414 #ifdef CONFIG_LINUX_AIO
 415         { "aio", 1, NULL, QEMU_NBD_OPT_AIO },
 416 #endif
 417         { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
 418         { "detect-zeroes", 1, NULL, QEMU_NBD_OPT_DETECT_ZEROES },
 419         { "shared", 1, NULL, 'e' },
 420         { "format", 1, NULL, 'f' },
 421         { "persistent", 0, NULL, 't' },
 422         { "verbose", 0, NULL, 'v' },
 423         { NULL, 0, NULL, 0 }
 424     };
 425     int ch;
 426     int opt_ind = 0;
 427     int li;
 428     char *end;
 429     int flags = BDRV_O_RDWR;
 430     int partition = -1;
 431     int ret;
 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
 443     /* The client thread uses SIGTERM to interrupt the server.  A signal
 444      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 445      */
 446     struct sigaction sa_sigterm;
 447     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 448     sa_sigterm.sa_handler = termsig_handler;
 449     sigaction(SIGTERM, &sa_sigterm, NULL);
 450     qemu_init_exec_dir(argv[0]);
 451
 452     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 453         switch (ch) {
 454         case 's':
 455             flags |= BDRV_O_SNAPSHOT;
 456             break;
 457         case 'n':
 458             optarg = (char *) "none";
 459             /* fallthrough */
 460         case QEMU_NBD_OPT_CACHE:
 461             if (seen_cache) {
 462                 errx(EXIT_FAILURE, "-n and --cache can only be specified once");
 463             }
 464             seen_cache = true;
 465             if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
 466                 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
 467             }
 468             break;
 469 #ifdef CONFIG_LINUX_AIO
 470         case QEMU_NBD_OPT_AIO:
 471             if (seen_aio) {
 472                 errx(EXIT_FAILURE, "--aio can only be specified once");
 473             }
 474             seen_aio = true;
 475             if (!strcmp(optarg, "native")) {
 476                 flags |= BDRV_O_NATIVE_AIO;
 477             } else if (!strcmp(optarg, "threads")) {
 478                 /* this is the default */
 479             } else {
 480                errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
 481             }
 482             break;
 483 #endif
 484         case QEMU_NBD_OPT_DISCARD:
 485             if (seen_discard) {
 486                 errx(EXIT_FAILURE, "--discard can only be specified once");
 487             }
 488             seen_discard = true;
 489             if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
 490                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
 491             }
 492             break;
 493         case QEMU_NBD_OPT_DETECT_ZEROES:
 494             detect_zeroes =
 495                 qapi_enum_parse(BlockdevDetectZeroesOptions_lookup,
 496                                 optarg,
 497                                 BLOCKDEV_DETECT_ZEROES_OPTIONS_MAX,
 498                                 BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF,
 499                                 &local_err);
 500             if (local_err) {
 501                 errx(EXIT_FAILURE, "Failed to parse detect_zeroes mode: %s",
 502                      error_get_pretty(local_err));
 503             }
 504             if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
 505                 !(flags & BDRV_O_UNMAP)) {
 506                 errx(EXIT_FAILURE, "setting detect-zeroes to unmap is not allowed "
 507                                    "without setting discard operation to unmap");
 508             }
 509             break;
 510         case 'b':
 511             bindto = optarg;
 512             break;
 513         case 'p':
 514             li = strtol(optarg, &end, 0);
 515             if (*end) {
 516                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 517             }
 518             if (li < 1 || li > 65535) {
 519                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 520             }
 521             port = (uint16_t)li;
 522             break;
 523         case 'o':
 524                 dev_offset = strtoll (optarg, &end, 0);
 525             if (*end) {
 526                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 527             }
 528             if (dev_offset < 0) {
 529                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 530             }
 531             break;
 532         case 'l':
 533             if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) {
 534                 sn_opts = qemu_opts_parse(&internal_snapshot_opts, optarg, 0);
 535                 if (!sn_opts) {
 536                     errx(EXIT_FAILURE, "Failed in parsing snapshot param `%s'",
 537                          optarg);
 538                 }
 539             } else {
 540                 sn_id_or_name = optarg;
 541             }
 542             /* fall through */
 543         case 'r':
 544             nbdflags |= NBD_FLAG_READ_ONLY;
 545             flags &= ~BDRV_O_RDWR;
 546             break;
 547         case 'P':
 548             partition = strtol(optarg, &end, 0);
 549             if (*end) {
 550                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 551             }
 552             if (partition < 1 || partition > 8) {
 553                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 554             }
 555             break;
 556         case 'k':
 557             sockpath = optarg;
 558             if (sockpath[0] != '/') {
 559                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 560             }
 561             break;
 562         case 'd':
 563             disconnect = true;
 564             break;
 565         case 'c':
 566             device = optarg;
 567             break;
 568         case 'e':
 569             shared = strtol(optarg, &end, 0);
 570             if (*end) {
 571                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 572             }
 573             if (shared < 1) {
 574                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 575             }
 576             break;
 577         case 'f':
 578             fmt = optarg;
 579             break;
 580         case 't':
 581             persistent = 1;
 582             break;
 583         case 'v':
 584             verbose = 1;
 585             break;
 586         case 'V':
 587             version(argv[0]);
 588             exit(0);
 589             break;
 590         case 'h':
 591             usage(argv[0]);
 592             exit(0);
 593             break;
 594         case '?':
 595             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 596                  argv[0]);
 597         }
 598     }
 599
 600     if ((argc - optind) != 1) {
 601         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 602              "Try `%s --help' for more information.",
 603              argv[0]);
 604     }
 605
 606     if (disconnect) {
 607         fd = open(argv[optind], O_RDWR);
 608         if (fd < 0) {
 609             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 610         }
 611         nbd_disconnect(fd);
 612
 613         close(fd);
 614
 615         printf("%s disconnected\n", argv[optind]);
 616
 617         return 0;
 618     }
 619
 620     if (device && !verbose) {
 621         int stderr_fd[2];
 622         pid_t pid;
 623         int ret;
 624
 625         if (qemu_pipe(stderr_fd) < 0) {
 626             err(EXIT_FAILURE, "Error setting up communication pipe");
 627         }
 628
 629         /* Now daemonize, but keep a communication channel open to
 630          * print errors and exit with the proper status code.
 631          */
 632         pid = fork();
 633         if (pid == 0) {
 634             close(stderr_fd[0]);
 635             ret = qemu_daemon(1, 0);
 636
 637             /* Temporarily redirect stderr to the parent's pipe...  */
 638             dup2(stderr_fd[1], STDERR_FILENO);
 639             if (ret < 0) {
 640                 err(EXIT_FAILURE, "Failed to daemonize");
 641             }
 642
 643             /* ... close the descriptor we inherited and go on.  */
 644             close(stderr_fd[1]);
 645         } else {
 646             bool errors = false;
 647             char *buf;
 648
 649             /* In the parent.  Print error messages from the child until
 650              * it closes the pipe.
 651              */
 652             close(stderr_fd[1]);
 653             buf = g_malloc(1024);
 654             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 655                 errors = true;
 656                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 657                 if (ret < 0) {
 658                     exit(EXIT_FAILURE);
 659                 }
 660             }
 661             if (ret < 0) {
 662                 err(EXIT_FAILURE, "Cannot read from daemon");
 663             }
 664
 665             /* Usually the daemon should not print any message.
 666              * Exit with zero status in that case.
 667              */
 668             exit(errors);
 669         }
 670     }
 671
 672     if (device != NULL && sockpath == NULL) {
 673         sockpath = g_malloc(128);
 674         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 675     }
 676
 677     if (qemu_init_main_loop(&local_err)) {
 678         error_report("%s", error_get_pretty(local_err));
 679         error_free(local_err);
 680         exit(EXIT_FAILURE);
 681     }
 682     bdrv_init();
 683     atexit(bdrv_close_all);
 684
 685     if (fmt) {
 686         drv = bdrv_find_format(fmt);
 687         if (!drv) {
 688             errx(EXIT_FAILURE, "Unknown file format '%s'", fmt);
 689         }
 690     } else {
 691         drv = NULL;
 692     }
 693
 694     bs = bdrv_new("hda", &error_abort);
 695
 696     srcpath = argv[optind];
 697     ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);
 698     if (ret < 0) {
 699         errno = -ret;
 700         err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind],
 701             error_get_pretty(local_err));
 702     }
 703
 704     if (sn_opts) {
 705         ret = bdrv_snapshot_load_tmp(bs,
 706                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID),
 707                                      qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME),
 708                                      &local_err);
 709     } else if (sn_id_or_name) {
 710         ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name,
 711                                                    &local_err);
 712     }
 713     if (ret < 0) {
 714         errno = -ret;
 715         err(EXIT_FAILURE,
 716             "Failed to load snapshot: %s",
 717             error_get_pretty(local_err));
 718     }
 719
 720     bs->detect_zeroes = detect_zeroes;
 721     fd_size = bdrv_getlength(bs);
 722
 723     if (partition != -1) {
 724         ret = find_partition(bs, partition, &dev_offset, &fd_size);
 725         if (ret < 0) {
 726             errno = -ret;
 727             err(EXIT_FAILURE, "Could not find partition %d", partition);
 728         }
 729     }
 730
 731     exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed);
 732
 733     if (sockpath) {
 734         fd = unix_socket_incoming(sockpath);
 735     } else {
 736         fd = tcp_socket_incoming(bindto, port);
 737     }
 738
 739     if (fd < 0) {
 740         return 1;
 741     }
 742
 743     if (device) {
 744         int ret;
 745
 746         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 747         if (ret != 0) {
 748             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 749                  strerror(ret));
 750         }
 751     } else {
 752         /* Shut up GCC warnings.  */
 753         memset(&client_thread, 0, sizeof(client_thread));
 754     }
 755
 756     qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
 757                          (void *)(uintptr_t)fd);
 758
 759     /* now when the initialization is (almost) complete, chdir("/")
 760      * to free any busy filesystems */
 761     if (chdir("/") < 0) {
 762         err(EXIT_FAILURE, "Could not chdir to root directory");
 763     }
 764
 765     state = RUNNING;
 766     do {
 767         main_loop_wait(false);
 768         if (state == TERMINATE) {
 769             state = TERMINATING;
 770             nbd_export_close(exp);
 771             nbd_export_put(exp);
 772             exp = NULL;
 773         }
 774     } while (state != TERMINATED);
 775
 776     bdrv_unref(bs);
 777     if (sockpath) {
 778         unlink(sockpath);
 779     }
 780
 781     if (sn_opts) {
 782         qemu_opts_del(sn_opts);
 783     }
 784
 785     if (device) {
 786         void *ret;
 787         pthread_join(client_thread, &ret);
 788         exit(ret != NULL);
 789     } else {
 790         exit(EXIT_SUCCESS);
 791     }
 792 }