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; 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; 299 } 300 301 ret = nbd_init(fd, sock, nbdflags, size, blocksize); 302 if (ret < 0) { 303 goto out; 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; 320 } 321 close(fd); 322 kill(getpid(), SIGTERM); 323 return (void *) EXIT_SUCCESS; 324 325 out: 326 kill(getpid(), SIGTERM); 327 return (void *) EXIT_FAILURE; 328 } 329 330 static int nbd_can_accept(void *opaque) 331 { 332 return nb_fds < shared; 333 } 334 335 static void nbd_export_closed(NBDExport *exp) 336 { 337 assert(state == TERMINATING); 338 state = TERMINATED; 339 } 340 341 static void nbd_client_closed(NBDClient *client) 342 { 343 nb_fds--; 344 if (nb_fds == 0 && !persistent && state == RUNNING) { 345 state = TERMINATE; 346 } 347 qemu_notify_event(); 348 nbd_client_put(client); 349 } 350 351 static void nbd_accept(void *opaque) 352 { 353 int server_fd = (uintptr_t) opaque; 354 struct sockaddr_in addr; 355 socklen_t addr_len = sizeof(addr); 356 357 int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len); 358 if (state >= TERMINATE) { 359 close(fd); 360 return; 361 } 362 363 if (fd >= 0 && nbd_client_new(exp, fd, nbd_client_closed)) { 364 nb_fds++; 365 } 366 } 367 368 int main(int argc, char **argv) 369 { 370 BlockDriverState *bs; 371 BlockDriver *drv; 372 off_t dev_offset = 0; 373 uint32_t nbdflags = 0; 374 bool disconnect = false; 375 const char *bindto = "0.0.0.0"; 376 char *device = NULL; 377 int port = NBD_DEFAULT_PORT; 378 off_t fd_size; 379 QemuOpts *sn_opts = NULL; 380 const char *sn_id_or_name = NULL; 381 const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:tl:"; 382 struct option lopt[] = { 383 { "help", 0, NULL, 'h' }, 384 { "version", 0, NULL, 'V' }, 385 { "bind", 1, NULL, 'b' }, 386 { "port", 1, NULL, 'p' }, 387 { "socket", 1, NULL, 'k' }, 388 { "offset", 1, NULL, 'o' }, 389 { "read-only", 0, NULL, 'r' }, 390 { "partition", 1, NULL, 'P' }, 391 { "connect", 1, NULL, 'c' }, 392 { "disconnect", 0, NULL, 'd' }, 393 { "snapshot", 0, NULL, 's' }, 394 { "load-snapshot", 1, NULL, 'l' }, 395 { "nocache", 0, NULL, 'n' }, 396 { "cache", 1, NULL, QEMU_NBD_OPT_CACHE }, 397 #ifdef CONFIG_LINUX_AIO 398 { "aio", 1, NULL, QEMU_NBD_OPT_AIO }, 399 #endif 400 { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD }, 401 { "shared", 1, NULL, 'e' }, 402 { "format", 1, NULL, 'f' }, 403 { "persistent", 0, NULL, 't' }, 404 { "verbose", 0, NULL, 'v' }, 405 { NULL, 0, NULL, 0 } 406 }; 407 int ch; 408 int opt_ind = 0; 409 int li; 410 char *end; 411 int flags = BDRV_O_RDWR; 412 int partition = -1; 413 int ret; 414 int fd; 415 bool seen_cache = false; 416 bool seen_discard = false; 417 #ifdef CONFIG_LINUX_AIO 418 bool seen_aio = false; 419 #endif 420 pthread_t client_thread; 421 const char *fmt = NULL; 422 Error *local_err = NULL; 423 424 /* The client thread uses SIGTERM to interrupt the server. A signal 425 * handler ensures that "qemu-nbd -v -c" exits with a nice status code. 426 */ 427 struct sigaction sa_sigterm; 428 memset(&sa_sigterm, 0, sizeof(sa_sigterm)); 429 sa_sigterm.sa_handler = termsig_handler; 430 sigaction(SIGTERM, &sa_sigterm, NULL); 431 qemu_init_exec_dir(argv[0]); 432 433 while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) { 434 switch (ch) { 435 case 's': 436 flags |= BDRV_O_SNAPSHOT; 437 break; 438 case 'n': 439 optarg = (char *) "none"; 440 /* fallthrough */ 441 case QEMU_NBD_OPT_CACHE: 442 if (seen_cache) { 443 errx(EXIT_FAILURE, "-n and --cache can only be specified once"); 444 } 445 seen_cache = true; 446 if (bdrv_parse_cache_flags(optarg, &flags) == -1) { 447 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg); 448 } 449 break; 450 #ifdef CONFIG_LINUX_AIO 451 case QEMU_NBD_OPT_AIO: 452 if (seen_aio) { 453 errx(EXIT_FAILURE, "--aio can only be specified once"); 454 } 455 seen_aio = true; 456 if (!strcmp(optarg, "native")) { 457 flags |= BDRV_O_NATIVE_AIO; 458 } else if (!strcmp(optarg, "threads")) { 459 /* this is the default */ 460 } else { 461 errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg); 462 } 463 break; 464 #endif 465 case QEMU_NBD_OPT_DISCARD: 466 if (seen_discard) { 467 errx(EXIT_FAILURE, "--discard can only be specified once"); 468 } 469 seen_discard = true; 470 if (bdrv_parse_discard_flags(optarg, &flags) == -1) { 471 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg); 472 } 473 break; 474 case 'b': 475 bindto = optarg; 476 break; 477 case 'p': 478 li = strtol(optarg, &end, 0); 479 if (*end) { 480 errx(EXIT_FAILURE, "Invalid port `%s'", optarg); 481 } 482 if (li < 1 || li > 65535) { 483 errx(EXIT_FAILURE, "Port out of range `%s'", optarg); 484 } 485 port = (uint16_t)li; 486 break; 487 case 'o': 488 dev_offset = strtoll (optarg, &end, 0); 489 if (*end) { 490 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg); 491 } 492 if (dev_offset < 0) { 493 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg); 494 } 495 break; 496 case 'l': 497 if (strstart(optarg, SNAPSHOT_OPT_BASE, NULL)) { 498 sn_opts = qemu_opts_parse(&internal_snapshot_opts, optarg, 0); 499 if (!sn_opts) { 500 errx(EXIT_FAILURE, "Failed in parsing snapshot param `%s'", 501 optarg); 502 } 503 } else { 504 sn_id_or_name = optarg; 505 } 506 /* fall through */ 507 case 'r': 508 nbdflags |= NBD_FLAG_READ_ONLY; 509 flags &= ~BDRV_O_RDWR; 510 break; 511 case 'P': 512 partition = strtol(optarg, &end, 0); 513 if (*end) 514 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg); 515 if (partition < 1 || partition > 8) 516 errx(EXIT_FAILURE, "Invalid partition %d", partition); 517 break; 518 case 'k': 519 sockpath = optarg; 520 if (sockpath[0] != '/') 521 errx(EXIT_FAILURE, "socket path must be absolute\n"); 522 break; 523 case 'd': 524 disconnect = true; 525 break; 526 case 'c': 527 device = optarg; 528 break; 529 case 'e': 530 shared = strtol(optarg, &end, 0); 531 if (*end) { 532 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg); 533 } 534 if (shared < 1) { 535 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n"); 536 } 537 break; 538 case 'f': 539 fmt = optarg; 540 break; 541 case 't': 542 persistent = 1; 543 break; 544 case 'v': 545 verbose = 1; 546 break; 547 case 'V': 548 version(argv[0]); 549 exit(0); 550 break; 551 case 'h': 552 usage(argv[0]); 553 exit(0); 554 break; 555 case '?': 556 errx(EXIT_FAILURE, "Try `%s --help' for more information.", 557 argv[0]); 558 } 559 } 560 561 if ((argc - optind) != 1) { 562 errx(EXIT_FAILURE, "Invalid number of argument.\n" 563 "Try `%s --help' for more information.", 564 argv[0]); 565 } 566 567 if (disconnect) { 568 fd = open(argv[optind], O_RDWR); 569 if (fd < 0) { 570 err(EXIT_FAILURE, "Cannot open %s", argv[optind]); 571 } 572 nbd_disconnect(fd); 573 574 close(fd); 575 576 printf("%s disconnected\n", argv[optind]); 577 578 return 0; 579 } 580 581 if (device && !verbose) { 582 int stderr_fd[2]; 583 pid_t pid; 584 int ret; 585 586 if (qemu_pipe(stderr_fd) < 0) { 587 err(EXIT_FAILURE, "Error setting up communication pipe"); 588 } 589 590 /* Now daemonize, but keep a communication channel open to 591 * print errors and exit with the proper status code. 592 */ 593 pid = fork(); 594 if (pid == 0) { 595 close(stderr_fd[0]); 596 ret = qemu_daemon(1, 0); 597 598 /* Temporarily redirect stderr to the parent's pipe... */ 599 dup2(stderr_fd[1], STDERR_FILENO); 600 if (ret < 0) { 601 err(EXIT_FAILURE, "Failed to daemonize"); 602 } 603 604 /* ... close the descriptor we inherited and go on. */ 605 close(stderr_fd[1]); 606 } else { 607 bool errors = false; 608 char *buf; 609 610 /* In the parent. Print error messages from the child until 611 * it closes the pipe. 612 */ 613 close(stderr_fd[1]); 614 buf = g_malloc(1024); 615 while ((ret = read(stderr_fd[0], buf, 1024)) > 0) { 616 errors = true; 617 ret = qemu_write_full(STDERR_FILENO, buf, ret); 618 if (ret < 0) { 619 exit(EXIT_FAILURE); 620 } 621 } 622 if (ret < 0) { 623 err(EXIT_FAILURE, "Cannot read from daemon"); 624 } 625 626 /* Usually the daemon should not print any message. 627 * Exit with zero status in that case. 628 */ 629 exit(errors); 630 } 631 } 632 633 if (device != NULL && sockpath == NULL) { 634 sockpath = g_malloc(128); 635 snprintf(sockpath, 128, SOCKET_PATH, basename(device)); 636 } 637 638 qemu_init_main_loop(); 639 bdrv_init(); 640 atexit(bdrv_close_all); 641 642 if (fmt) { 643 drv = bdrv_find_format(fmt); 644 if (!drv) { 645 errx(EXIT_FAILURE, "Unknown file format '%s'", fmt); 646 } 647 } else { 648 drv = NULL; 649 } 650 651 bs = bdrv_new("hda"); 652 srcpath = argv[optind]; 653 ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err); 654 if (ret < 0) { 655 errno = -ret; 656 err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind], 657 error_get_pretty(local_err)); 658 } 659 660 if (sn_opts) { 661 ret = bdrv_snapshot_load_tmp(bs, 662 qemu_opt_get(sn_opts, SNAPSHOT_OPT_ID), 663 qemu_opt_get(sn_opts, SNAPSHOT_OPT_NAME), 664 &local_err); 665 } else if (sn_id_or_name) { 666 ret = bdrv_snapshot_load_tmp_by_id_or_name(bs, sn_id_or_name, 667 &local_err); 668 } 669 if (ret < 0) { 670 errno = -ret; 671 err(EXIT_FAILURE, 672 "Failed to load snapshot: %s", 673 error_get_pretty(local_err)); 674 } 675 676 fd_size = bdrv_getlength(bs); 677 678 if (partition != -1) { 679 ret = find_partition(bs, partition, &dev_offset, &fd_size); 680 if (ret < 0) { 681 errno = -ret; 682 err(EXIT_FAILURE, "Could not find partition %d", partition); 683 } 684 } 685 686 exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed); 687 688 if (sockpath) { 689 fd = unix_socket_incoming(sockpath); 690 } else { 691 fd = tcp_socket_incoming(bindto, port); 692 } 693 694 if (fd < 0) { 695 return 1; 696 } 697 698 if (device) { 699 int ret; 700 701 ret = pthread_create(&client_thread, NULL, nbd_client_thread, device); 702 if (ret != 0) { 703 errx(EXIT_FAILURE, "Failed to create client thread: %s", 704 strerror(ret)); 705 } 706 } else { 707 /* Shut up GCC warnings. */ 708 memset(&client_thread, 0, sizeof(client_thread)); 709 } 710 711 qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL, 712 (void *)(uintptr_t)fd); 713 714 /* now when the initialization is (almost) complete, chdir("/") 715 * to free any busy filesystems */ 716 if (chdir("/") < 0) { 717 err(EXIT_FAILURE, "Could not chdir to root directory"); 718 } 719 720 state = RUNNING; 721 do { 722 main_loop_wait(false); 723 if (state == TERMINATE) { 724 state = TERMINATING; 725 nbd_export_close(exp); 726 nbd_export_put(exp); 727 exp = NULL; 728 } 729 } while (state != TERMINATED); 730 731 bdrv_close(bs); 732 if (sockpath) { 733 unlink(sockpath); 734 } 735 736 if (sn_opts) { 737 qemu_opts_del(sn_opts); 738 } 739 740 if (device) { 741 void *ret; 742 pthread_join(client_thread, &ret); 743 exit(ret != NULL); 744 } else { 745 exit(EXIT_SUCCESS); 746 } 747 } 748