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_int.h"
  21 #include "nbd.h"
  22
  23 #include <stdarg.h>
  24 #include <stdio.h>
  25 #include <getopt.h>
  26 #include <err.h>
  27 #include <sys/types.h>
  28 #include <sys/socket.h>
  29 #include <netinet/in.h>
  30 #include <netinet/tcp.h>
  31 #include <arpa/inet.h>
  32 #include <signal.h>
  33 #include <libgen.h>
  34 #include <pthread.h>
  35
  36 #define SOCKET_PATH    "/var/lock/qemu-nbd-%s"
  37
  38 static NBDExport *exp;
  39 static int verbose;
  40 static char *srcpath;
  41 static char *sockpath;
  42 static bool sigterm_reported;
  43 static bool nbd_started;
  44 static int shared = 1;
  45 static int nb_fds;
  46
  47 static void usage(const char *name)
  48 {
  49     printf(
  50 "Usage: %s [OPTIONS] FILE\n"
  51 "QEMU Disk Network Block Device Server\n"
  52 "\n"
  53 "  -p, --port=PORT      port to listen on (default `%d')\n"
  54 "  -o, --offset=OFFSET  offset into the image\n"
  55 "  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
  56 "  -k, --socket=PATH    path to the unix socket\n"
  57 "                       (default '"SOCKET_PATH"')\n"
  58 "  -r, --read-only      export read-only\n"
  59 "  -P, --partition=NUM  only expose partition NUM\n"
  60 "  -s, --snapshot       use snapshot file\n"
  61 "  -n, --nocache        disable host cache\n"
  62 "  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
  63 "  -d, --disconnect     disconnect the specified device\n"
  64 "  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
  65 "  -t, --persistent     don't exit on the last connection\n"
  66 "  -v, --verbose        display extra debugging information\n"
  67 "  -h, --help           display this help and exit\n"
  68 "  -V, --version        output version information and exit\n"
  69 "\n"
  70 "Report bugs to <anthony@codemonkey.ws>\n"
  71     , name, NBD_DEFAULT_PORT, "DEVICE");
  72 }
  73
  74 static void version(const char *name)
  75 {
  76     printf(
  77 "%s version 0.0.1\n"
  78 "Written by Anthony Liguori.\n"
  79 "\n"
  80 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
  81 "This is free software; see the source for copying conditions.  There is NO\n"
  82 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
  83     , name);
  84 }
  85
  86 struct partition_record
  87 {
  88     uint8_t bootable;
  89     uint8_t start_head;
  90     uint32_t start_cylinder;
  91     uint8_t start_sector;
  92     uint8_t system;
  93     uint8_t end_head;
  94     uint8_t end_cylinder;
  95     uint8_t end_sector;
  96     uint32_t start_sector_abs;
  97     uint32_t nb_sectors_abs;
  98 };
  99
 100 static void read_partition(uint8_t *p, struct partition_record *r)
 101 {
 102     r->bootable = p[0];
 103     r->start_head = p[1];
 104     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
 105     r->start_sector = p[2] & 0x3f;
 106     r->system = p[4];
 107     r->end_head = p[5];
 108     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 109     r->end_sector = p[6] & 0x3f;
 110     r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 111     r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 112 }
 113
 114 static int find_partition(BlockDriverState *bs, int partition,
 115                           off_t *offset, off_t *size)
 116 {
 117     struct partition_record mbr[4];
 118     uint8_t data[512];
 119     int i;
 120     int ext_partnum = 4;
 121     int ret;
 122
 123     if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 124         errno = -ret;
 125         err(EXIT_FAILURE, "error while reading");
 126     }
 127
 128     if (data[510] != 0x55 || data[511] != 0xaa) {
 129         errno = -EINVAL;
 130         return -1;
 131     }
 132
 133     for (i = 0; i < 4; i++) {
 134         read_partition(&data[446 + 16 * i], &mbr[i]);
 135
 136         if (!mbr[i].nb_sectors_abs)
 137             continue;
 138
 139         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 140             struct partition_record ext[4];
 141             uint8_t data1[512];
 142             int j;
 143
 144             if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 145                 errno = -ret;
 146                 err(EXIT_FAILURE, "error while reading");
 147             }
 148
 149             for (j = 0; j < 4; j++) {
 150                 read_partition(&data1[446 + 16 * j], &ext[j]);
 151                 if (!ext[j].nb_sectors_abs)
 152                     continue;
 153
 154                 if ((ext_partnum + j + 1) == partition) {
 155                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 156                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 157                     return 0;
 158                 }
 159             }
 160             ext_partnum += 4;
 161         } else if ((i + 1) == partition) {
 162             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 163             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 164             return 0;
 165         }
 166     }
 167
 168     errno = -ENOENT;
 169     return -1;
 170 }
 171
 172 static void termsig_handler(int signum)
 173 {
 174     sigterm_reported = true;
 175     qemu_notify_event();
 176 }
 177
 178 static void *show_parts(void *arg)
 179 {
 180     char *device = arg;
 181     int nbd;
 182
 183     /* linux just needs an open() to trigger
 184      * the partition table update
 185      * but remember to load the module with max_part != 0 :
 186      *     modprobe nbd max_part=63
 187      */
 188     nbd = open(device, O_RDWR);
 189     if (nbd != -1) {
 190         close(nbd);
 191     }
 192     return NULL;
 193 }
 194
 195 static void *nbd_client_thread(void *arg)
 196 {
 197     char *device = arg;
 198     off_t size;
 199     size_t blocksize;
 200     uint32_t nbdflags;
 201     int fd, sock;
 202     int ret;
 203     pthread_t show_parts_thread;
 204
 205     sock = unix_socket_outgoing(sockpath);
 206     if (sock == -1) {
 207         goto out;
 208     }
 209
 210     ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 211                                 &size, &blocksize);
 212     if (ret == -1) {
 213         goto out;
 214     }
 215
 216     fd = open(device, O_RDWR);
 217     if (fd == -1) {
 218         /* Linux-only, we can use %m in printf.  */
 219         fprintf(stderr, "Failed to open %s: %m", device);
 220         goto out;
 221     }
 222
 223     ret = nbd_init(fd, sock, nbdflags, size, blocksize);
 224     if (ret == -1) {
 225         goto out;
 226     }
 227
 228     /* update partition table */
 229     pthread_create(&show_parts_thread, NULL, show_parts, device);
 230
 231     if (verbose) {
 232         fprintf(stderr, "NBD device %s is now connected to %s\n",
 233                 device, srcpath);
 234     } else {
 235         /* Close stderr so that the qemu-nbd process exits.  */
 236         dup2(STDOUT_FILENO, STDERR_FILENO);
 237     }
 238
 239     ret = nbd_client(fd);
 240     if (ret) {
 241         goto out;
 242     }
 243     close(fd);
 244     kill(getpid(), SIGTERM);
 245     return (void *) EXIT_SUCCESS;
 246
 247 out:
 248     kill(getpid(), SIGTERM);
 249     return (void *) EXIT_FAILURE;
 250 }
 251
 252 static int nbd_can_accept(void *opaque)
 253 {
 254     return nb_fds < shared;
 255 }
 256
 257 static void nbd_client_closed(NBDClient *client)
 258 {
 259     nb_fds--;
 260     qemu_notify_event();
 261 }
 262
 263 static void nbd_accept(void *opaque)
 264 {
 265     int server_fd = (uintptr_t) opaque;
 266     struct sockaddr_in addr;
 267     socklen_t addr_len = sizeof(addr);
 268
 269     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
 270     nbd_started = true;
 271     if (fd != -1 && nbd_client_new(exp, fd, nbd_client_closed)) {
 272         nb_fds++;
 273     }
 274 }
 275
 276 int main(int argc, char **argv)
 277 {
 278     BlockDriverState *bs;
 279     off_t dev_offset = 0;
 280     uint32_t nbdflags = 0;
 281     bool disconnect = false;
 282     const char *bindto = "0.0.0.0";
 283     char *device = NULL;
 284     int port = NBD_DEFAULT_PORT;
 285     off_t fd_size;
 286     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";
 287     struct option lopt[] = {
 288         { "help", 0, NULL, 'h' },
 289         { "version", 0, NULL, 'V' },
 290         { "bind", 1, NULL, 'b' },
 291         { "port", 1, NULL, 'p' },
 292         { "socket", 1, NULL, 'k' },
 293         { "offset", 1, NULL, 'o' },
 294         { "read-only", 0, NULL, 'r' },
 295         { "partition", 1, NULL, 'P' },
 296         { "connect", 1, NULL, 'c' },
 297         { "disconnect", 0, NULL, 'd' },
 298         { "snapshot", 0, NULL, 's' },
 299         { "nocache", 0, NULL, 'n' },
 300         { "shared", 1, NULL, 'e' },
 301         { "persistent", 0, NULL, 't' },
 302         { "verbose", 0, NULL, 'v' },
 303         { NULL, 0, NULL, 0 }
 304     };
 305     int ch;
 306     int opt_ind = 0;
 307     int li;
 308     char *end;
 309     int flags = BDRV_O_RDWR;
 310     int partition = -1;
 311     int ret;
 312     int fd;
 313     int persistent = 0;
 314     pthread_t client_thread;
 315
 316     /* The client thread uses SIGTERM to interrupt the server.  A signal
 317      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 318      */
 319     struct sigaction sa_sigterm;
 320     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 321     sa_sigterm.sa_handler = termsig_handler;
 322     sigaction(SIGTERM, &sa_sigterm, NULL);
 323
 324     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 325         switch (ch) {
 326         case 's':
 327             flags |= BDRV_O_SNAPSHOT;
 328             break;
 329         case 'n':
 330             flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
 331             break;
 332         case 'b':
 333             bindto = optarg;
 334             break;
 335         case 'p':
 336             li = strtol(optarg, &end, 0);
 337             if (*end) {
 338                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 339             }
 340             if (li < 1 || li > 65535) {
 341                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 342             }
 343             port = (uint16_t)li;
 344             break;
 345         case 'o':
 346                 dev_offset = strtoll (optarg, &end, 0);
 347             if (*end) {
 348                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 349             }
 350             if (dev_offset < 0) {
 351                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 352             }
 353             break;
 354         case 'r':
 355             nbdflags |= NBD_FLAG_READ_ONLY;
 356             flags &= ~BDRV_O_RDWR;
 357             break;
 358         case 'P':
 359             partition = strtol(optarg, &end, 0);
 360             if (*end)
 361                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 362             if (partition < 1 || partition > 8)
 363                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 364             break;
 365         case 'k':
 366             sockpath = optarg;
 367             if (sockpath[0] != '/')
 368                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 369             break;
 370         case 'd':
 371             disconnect = true;
 372             break;
 373         case 'c':
 374             device = optarg;
 375             break;
 376         case 'e':
 377             shared = strtol(optarg, &end, 0);
 378             if (*end) {
 379                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 380             }
 381             if (shared < 1) {
 382                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 383             }
 384             break;
 385         case 't':
 386             persistent = 1;
 387             break;
 388         case 'v':
 389             verbose = 1;
 390             break;
 391         case 'V':
 392             version(argv[0]);
 393             exit(0);
 394             break;
 395         case 'h':
 396             usage(argv[0]);
 397             exit(0);
 398             break;
 399         case '?':
 400             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 401                  argv[0]);
 402         }
 403     }
 404
 405     if ((argc - optind) != 1) {
 406         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 407              "Try `%s --help' for more information.",
 408              argv[0]);
 409     }
 410
 411     if (disconnect) {
 412         fd = open(argv[optind], O_RDWR);
 413         if (fd == -1)
 414             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 415
 416         nbd_disconnect(fd);
 417
 418         close(fd);
 419
 420         printf("%s disconnected\n", argv[optind]);
 421
 422         return 0;
 423     }
 424
 425     if (device && !verbose) {
 426         int stderr_fd[2];
 427         pid_t pid;
 428         int ret;
 429
 430         if (qemu_pipe(stderr_fd) == -1) {
 431             err(EXIT_FAILURE, "Error setting up communication pipe");
 432         }
 433
 434         /* Now daemonize, but keep a communication channel open to
 435          * print errors and exit with the proper status code.
 436          */
 437         pid = fork();
 438         if (pid == 0) {
 439             close(stderr_fd[0]);
 440             ret = qemu_daemon(1, 0);
 441
 442             /* Temporarily redirect stderr to the parent's pipe...  */
 443             dup2(stderr_fd[1], STDERR_FILENO);
 444             if (ret == -1) {
 445                 err(EXIT_FAILURE, "Failed to daemonize");
 446             }
 447
 448             /* ... close the descriptor we inherited and go on.  */
 449             close(stderr_fd[1]);
 450         } else {
 451             bool errors = false;
 452             char *buf;
 453
 454             /* In the parent.  Print error messages from the child until
 455              * it closes the pipe.
 456              */
 457             close(stderr_fd[1]);
 458             buf = g_malloc(1024);
 459             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 460                 errors = true;
 461                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 462                 if (ret == -1) {
 463                     exit(EXIT_FAILURE);
 464                 }
 465             }
 466             if (ret == -1) {
 467                 err(EXIT_FAILURE, "Cannot read from daemon");
 468             }
 469
 470             /* Usually the daemon should not print any message.
 471              * Exit with zero status in that case.
 472              */
 473             exit(errors);
 474         }
 475     }
 476
 477     if (device != NULL && sockpath == NULL) {
 478         sockpath = g_malloc(128);
 479         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 480     }
 481
 482     bdrv_init();
 483     atexit(bdrv_close_all);
 484
 485     bs = bdrv_new("hda");
 486     srcpath = argv[optind];
 487     if ((ret = bdrv_open(bs, srcpath, flags, NULL)) < 0) {
 488         errno = -ret;
 489         err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);
 490     }
 491
 492     fd_size = bs->total_sectors * 512;
 493
 494     if (partition != -1 &&
 495         find_partition(bs, partition, &dev_offset, &fd_size)) {
 496         err(EXIT_FAILURE, "Could not find partition %d", partition);
 497     }
 498
 499     exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags);
 500
 501     if (sockpath) {
 502         fd = unix_socket_incoming(sockpath);
 503     } else {
 504         fd = tcp_socket_incoming(bindto, port);
 505     }
 506
 507     if (fd == -1) {
 508         return 1;
 509     }
 510
 511     if (device) {
 512         int ret;
 513
 514         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 515         if (ret != 0) {
 516             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 517                  strerror(ret));
 518         }
 519     } else {
 520         /* Shut up GCC warnings.  */
 521         memset(&client_thread, 0, sizeof(client_thread));
 522     }
 523
 524     qemu_init_main_loop();
 525     qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
 526                          (void *)(uintptr_t)fd);
 527
 528     /* now when the initialization is (almost) complete, chdir("/")
 529      * to free any busy filesystems */
 530     if (chdir("/") < 0) {
 531         err(EXIT_FAILURE, "Could not chdir to root directory");
 532     }
 533
 534     do {
 535         main_loop_wait(false);
 536     } while (!sigterm_reported && (persistent || !nbd_started || nb_fds > 0));
 537
 538     nbd_export_close(exp);
 539     if (sockpath) {
 540         unlink(sockpath);
 541     }
 542
 543     if (device) {
 544         void *ret;
 545         pthread_join(client_thread, &ret);
 546         exit(ret != NULL);
 547     } else {
 548         exit(EXIT_SUCCESS);
 549     }
 550 }