qemu/qemu-nbd.c
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   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
  35#define SOCKET_PATH    "/var/lock/qemu-nbd-%s"
  36
  37#define NBD_BUFFER_SIZE (1024*1024)
  38
  39static int verbose;
  40
  41static void usage(const char *name)
  42{
  43    printf(
  44"Usage: %s [OPTIONS] FILE\n"
  45"QEMU Disk Network Block Device Server\n"
  46"\n"
  47"  -p, --port=PORT      port to listen on (default `1024')\n"
  48"  -o, --offset=OFFSET  offset into the image\n"
  49"  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
  50"  -k, --socket=PATH    path to the unix socket\n"
  51"                       (default '"SOCKET_PATH"')\n"
  52"  -r, --read-only      export read-only\n"
  53"  -P, --partition=NUM  only expose partition NUM\n"
  54"  -s, --snapshot       use snapshot file\n"
  55"  -n, --nocache        disable host cache\n"
  56"  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
  57"  -d, --disconnect     disconnect the specified device\n"
  58"  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
  59"  -t, --persistent     don't exit on the last connection\n"
  60"  -v, --verbose        display extra debugging information\n"
  61"  -h, --help           display this help and exit\n"
  62"  -V, --version        output version information and exit\n"
  63"\n"
  64"Report bugs to <anthony@codemonkey.ws>\n"
  65    , name, "DEVICE");
  66}
  67
  68static void version(const char *name)
  69{
  70    printf(
  71"%s version 0.0.1\n"
  72"Written by Anthony Liguori.\n"
  73"\n"
  74"Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
  75"This is free software; see the source for copying conditions.  There is NO\n"
  76"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
  77    , name);
  78}
  79
  80struct partition_record
  81{
  82    uint8_t bootable;
  83    uint8_t start_head;
  84    uint32_t start_cylinder;
  85    uint8_t start_sector;
  86    uint8_t system;
  87    uint8_t end_head;
  88    uint8_t end_cylinder;
  89    uint8_t end_sector;
  90    uint32_t start_sector_abs;
  91    uint32_t nb_sectors_abs;
  92};
  93
  94static void read_partition(uint8_t *p, struct partition_record *r)
  95{
  96    r->bootable = p[0];
  97    r->start_head = p[1];
  98    r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
  99    r->start_sector = p[2] & 0x3f;
 100    r->system = p[4];
 101    r->end_head = p[5];
 102    r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 103    r->end_sector = p[6] & 0x3f;
 104    r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 105    r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 106}
 107
 108static int find_partition(BlockDriverState *bs, int partition,
 109                          off_t *offset, off_t *size)
 110{
 111    struct partition_record mbr[4];
 112    uint8_t data[512];
 113    int i;
 114    int ext_partnum = 4;
 115    int ret;
 116
 117    if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 118        errno = -ret;
 119        err(EXIT_FAILURE, "error while reading");
 120    }
 121
 122    if (data[510] != 0x55 || data[511] != 0xaa) {
 123        errno = -EINVAL;
 124        return -1;
 125    }
 126
 127    for (i = 0; i < 4; i++) {
 128        read_partition(&data[446 + 16 * i], &mbr[i]);
 129
 130        if (!mbr[i].nb_sectors_abs)
 131            continue;
 132
 133        if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 134            struct partition_record ext[4];
 135            uint8_t data1[512];
 136            int j;
 137
 138            if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 139                errno = -ret;
 140                err(EXIT_FAILURE, "error while reading");
 141            }
 142
 143            for (j = 0; j < 4; j++) {
 144                read_partition(&data1[446 + 16 * j], &ext[j]);
 145                if (!ext[j].nb_sectors_abs)
 146                    continue;
 147
 148                if ((ext_partnum + j + 1) == partition) {
 149                    *offset = (uint64_t)ext[j].start_sector_abs << 9;
 150                    *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 151                    return 0;
 152                }
 153            }
 154            ext_partnum += 4;
 155        } else if ((i + 1) == partition) {
 156            *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 157            *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 158            return 0;
 159        }
 160    }
 161
 162    errno = -ENOENT;
 163    return -1;
 164}
 165
 166static void show_parts(const char *device)
 167{
 168    if (fork() == 0) {
 169        int nbd;
 170
 171        /* linux just needs an open() to trigger
 172         * the partition table update
 173         * but remember to load the module with max_part != 0 :
 174         *     modprobe nbd max_part=63
 175         */
 176        nbd = open(device, O_RDWR);
 177        if (nbd != -1)
 178              close(nbd);
 179        exit(0);
 180    }
 181}
 182
 183int main(int argc, char **argv)
 184{
 185    BlockDriverState *bs;
 186    off_t dev_offset = 0;
 187    off_t offset = 0;
 188    bool readonly = false;
 189    bool disconnect = false;
 190    const char *bindto = "0.0.0.0";
 191    int port = 1024;
 192    struct sockaddr_in addr;
 193    socklen_t addr_len = sizeof(addr);
 194    off_t fd_size;
 195    char *device = NULL;
 196    char *socket = NULL;
 197    char sockpath[128];
 198    const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";
 199    struct option lopt[] = {
 200        { "help", 0, NULL, 'h' },
 201        { "version", 0, NULL, 'V' },
 202        { "bind", 1, NULL, 'b' },
 203        { "port", 1, NULL, 'p' },
 204        { "socket", 1, NULL, 'k' },
 205        { "offset", 1, NULL, 'o' },
 206        { "read-only", 0, NULL, 'r' },
 207        { "partition", 1, NULL, 'P' },
 208        { "connect", 1, NULL, 'c' },
 209        { "disconnect", 0, NULL, 'd' },
 210        { "snapshot", 0, NULL, 's' },
 211        { "nocache", 0, NULL, 'n' },
 212        { "shared", 1, NULL, 'e' },
 213        { "persistent", 0, NULL, 't' },
 214        { "verbose", 0, NULL, 'v' },
 215        { NULL, 0, NULL, 0 }
 216    };
 217    int ch;
 218    int opt_ind = 0;
 219    int li;
 220    char *end;
 221    int flags = BDRV_O_RDWR;
 222    int partition = -1;
 223    int ret;
 224    int shared = 1;
 225    uint8_t *data;
 226    fd_set fds;
 227    int *sharing_fds;
 228    int fd;
 229    int i;
 230    int nb_fds = 0;
 231    int max_fd;
 232    int persistent = 0;
 233
 234    while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 235        switch (ch) {
 236        case 's':
 237            flags |= BDRV_O_SNAPSHOT;
 238            break;
 239        case 'n':
 240            flags |= BDRV_O_NOCACHE;
 241            break;
 242        case 'b':
 243            bindto = optarg;
 244            break;
 245        case 'p':
 246            li = strtol(optarg, &end, 0);
 247            if (*end) {
 248                errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 249            }
 250            if (li < 1 || li > 65535) {
 251                errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 252            }
 253            port = (uint16_t)li;
 254            break;
 255        case 'o':
 256                dev_offset = strtoll (optarg, &end, 0);
 257            if (*end) {
 258                errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 259            }
 260            if (dev_offset < 0) {
 261                errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 262            }
 263            break;
 264        case 'r':
 265            readonly = true;
 266            flags &= ~BDRV_O_RDWR;
 267            break;
 268        case 'P':
 269            partition = strtol(optarg, &end, 0);
 270            if (*end)
 271                errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 272            if (partition < 1 || partition > 8)
 273                errx(EXIT_FAILURE, "Invalid partition %d", partition);
 274            break;
 275        case 'k':
 276            socket = optarg;
 277            if (socket[0] != '/')
 278                errx(EXIT_FAILURE, "socket path must be absolute\n");
 279            break;
 280        case 'd':
 281            disconnect = true;
 282            break;
 283        case 'c':
 284            device = optarg;
 285            break;
 286        case 'e':
 287            shared = strtol(optarg, &end, 0);
 288            if (*end) {
 289                errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 290            }
 291            if (shared < 1) {
 292                errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 293            }
 294            break;
 295        case 't':
 296            persistent = 1;
 297            break;
 298        case 'v':
 299            verbose = 1;
 300            break;
 301        case 'V':
 302            version(argv[0]);
 303            exit(0);
 304            break;
 305        case 'h':
 306            usage(argv[0]);
 307            exit(0);
 308            break;
 309        case '?':
 310            errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 311                 argv[0]);
 312        }
 313    }
 314
 315    if ((argc - optind) != 1) {
 316        errx(EXIT_FAILURE, "Invalid number of argument.\n"
 317             "Try `%s --help' for more information.",
 318             argv[0]);
 319    }
 320
 321    if (disconnect) {
 322        fd = open(argv[optind], O_RDWR);
 323        if (fd == -1)
 324            err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 325
 326        nbd_disconnect(fd);
 327
 328        close(fd);
 329
 330        printf("%s disconnected\n", argv[optind]);
 331
 332        return 0;
 333    }
 334
 335    bdrv_init();
 336
 337    bs = bdrv_new("hda");
 338    if (bs == NULL)
 339        return 1;
 340
 341    if ((ret = bdrv_open(bs, argv[optind], flags, NULL)) < 0) {
 342        errno = -ret;
 343        err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);
 344    }
 345
 346    fd_size = bs->total_sectors * 512;
 347
 348    if (partition != -1 &&
 349        find_partition(bs, partition, &dev_offset, &fd_size))
 350        err(EXIT_FAILURE, "Could not find partition %d", partition);
 351
 352    if (device) {
 353        pid_t pid;
 354        int sock;
 355
 356        /* want to fail before daemonizing */
 357        if (access(device, R_OK|W_OK) == -1) {
 358            err(EXIT_FAILURE, "Could not access '%s'", device);
 359        }
 360
 361        if (!verbose) {
 362            /* detach client and server */
 363            if (daemon(0, 0) == -1) {
 364                err(EXIT_FAILURE, "Failed to daemonize");
 365            }
 366        }
 367
 368        if (socket == NULL) {
 369            snprintf(sockpath, sizeof(sockpath), SOCKET_PATH,
 370                     basename(device));
 371            socket = sockpath;
 372        }
 373
 374        pid = fork();
 375        if (pid < 0)
 376            return 1;
 377        if (pid != 0) {
 378            off_t size;
 379            size_t blocksize;
 380
 381            ret = 0;
 382            bdrv_close(bs);
 383
 384            do {
 385                sock = unix_socket_outgoing(socket);
 386                if (sock == -1) {
 387                    if (errno != ENOENT && errno != ECONNREFUSED) {
 388                        ret = 1;
 389                        goto out;
 390                    }
 391                    sleep(1);   /* wait children */
 392                }
 393            } while (sock == -1);
 394
 395            fd = open(device, O_RDWR);
 396            if (fd == -1) {
 397                ret = 1;
 398                goto out;
 399            }
 400
 401            ret = nbd_receive_negotiate(sock, &size, &blocksize);
 402            if (ret == -1) {
 403                ret = 1;
 404                goto out;
 405            }
 406
 407            ret = nbd_init(fd, sock, size, blocksize);
 408            if (ret == -1) {
 409                ret = 1;
 410                goto out;
 411            }
 412
 413            printf("NBD device %s is now connected to file %s\n",
 414                    device, argv[optind]);
 415
 416            /* update partition table */
 417
 418            show_parts(device);
 419
 420            nbd_client(fd, sock);
 421            close(fd);
 422 out:
 423            kill(pid, SIGTERM);
 424            unlink(socket);
 425
 426            return ret;
 427        }
 428        /* children */
 429    }
 430
 431    sharing_fds = qemu_malloc((shared + 1) * sizeof(int));
 432
 433    if (socket) {
 434        sharing_fds[0] = unix_socket_incoming(socket);
 435    } else {
 436        sharing_fds[0] = tcp_socket_incoming(bindto, port);
 437    }
 438
 439    if (sharing_fds[0] == -1)
 440        return 1;
 441    max_fd = sharing_fds[0];
 442    nb_fds++;
 443
 444    data = qemu_memalign(512, NBD_BUFFER_SIZE);
 445    if (data == NULL)
 446        errx(EXIT_FAILURE, "Cannot allocate data buffer");
 447
 448    do {
 449
 450        FD_ZERO(&fds);
 451        for (i = 0; i < nb_fds; i++)
 452            FD_SET(sharing_fds[i], &fds);
 453
 454        ret = select(max_fd + 1, &fds, NULL, NULL, NULL);
 455        if (ret == -1)
 456            break;
 457
 458        if (FD_ISSET(sharing_fds[0], &fds))
 459            ret--;
 460        for (i = 1; i < nb_fds && ret; i++) {
 461            if (FD_ISSET(sharing_fds[i], &fds)) {
 462                if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
 463                    &offset, readonly, data, NBD_BUFFER_SIZE) != 0) {
 464                    close(sharing_fds[i]);
 465                    nb_fds--;
 466                    sharing_fds[i] = sharing_fds[nb_fds];
 467                    i--;
 468                }
 469                ret--;
 470            }
 471        }
 472        /* new connection ? */
 473        if (FD_ISSET(sharing_fds[0], &fds)) {
 474            if (nb_fds < shared + 1) {
 475                sharing_fds[nb_fds] = accept(sharing_fds[0],
 476                                             (struct sockaddr *)&addr,
 477                                             &addr_len);
 478                if (sharing_fds[nb_fds] != -1 &&
 479                    nbd_negotiate(sharing_fds[nb_fds], fd_size) != -1) {
 480                        if (sharing_fds[nb_fds] > max_fd)
 481                            max_fd = sharing_fds[nb_fds];
 482                        nb_fds++;
 483                }
 484            }
 485        }
 486    } while (persistent || nb_fds > 1);
 487    qemu_vfree(data);
 488
 489    close(sharing_fds[0]);
 490    bdrv_close(bs);
 491    qemu_free(sharing_fds);
 492    if (socket)
 493        unlink(socket);
 494
 495    return 0;
 496}
 497