sbin/hammer/cmd_pseudofs.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sbin/hammer/cmd_pseudofs.c,v 1.12 2008/10/08 21:01:54 thomas Exp $
  35  */
  36
  37 #include "hammer.h"
  38
  39 static void parse_pfsd_options(char **av, int ac, hammer_pseudofs_data_t pfsd);
  40 static void init_pfsd(hammer_pseudofs_data_t pfsd, int is_slave);
  41 static void dump_pfsd(hammer_pseudofs_data_t pfsd);
  42 static void pseudofs_usage(int code);
  43 static int getyn(void);
  44
  45 /*
  46  * Calculate the pfs_id given a path to a directory or a @@PFS or @@%llx:%d
  47  * softlink.
  48  */
  49 int
  50 getpfs(struct hammer_ioc_pseudofs_rw *pfs, const char *path)
  51 {
  52         hammer_tid_t dummy_tid;
  53         struct stat st;
  54         char *dirpath;
  55         char buf[64];
  56         int fd;
  57         int n;
  58
  59         bzero(pfs, sizeof(*pfs));
  60         pfs->ondisk = malloc(sizeof(*pfs->ondisk));
  61         bzero(pfs->ondisk, sizeof(*pfs->ondisk));
  62         pfs->bytes = sizeof(*pfs->ondisk);
  63
  64         /*
  65          * Calculate the directory containing the softlink
  66          */
  67         dirpath = strdup(path);
  68         if (strrchr(dirpath, '/')) {
  69                 *strrchr(dirpath, '/') = 0;
  70                 if (strlen(dirpath) == 0) {
  71                         free(dirpath);
  72                         dirpath = strdup("/");
  73                 }
  74         } else {
  75                 free(dirpath);
  76                 dirpath = strdup(".");
  77         }
  78
  79         if (lstat(path, &st) == 0 && S_ISLNK(st.st_mode)) {
  80                 /*
  81                  * Avoid foot-shooting.  Don't let the user access a PFS
  82                  * softlink via a PFS.  PFS softlinks may only be accessed
  83                  * via the master filesystem.
  84                  */
  85                 fd = open(dirpath, O_RDONLY);
  86                 if (fd < 0)
  87                         goto done;
  88                 pfs->pfs_id = -1;
  89                 ioctl(fd, HAMMERIOC_GET_PSEUDOFS, pfs);
  90                 if (pfs->pfs_id != 0) {
  91                         fprintf(stderr,
  92                                 "You are attempting to access a PFS softlink "
  93                                 "from a PFS.  It may not represent the PFS\n"
  94                                 "on the main filesystem mount that you "
  95                                 "expect!  You may only access PFS softlinks\n"
  96                                 "via the main filesystem mount!\n");
  97                         exit(1);
  98                 }
  99                 close(fd);
 100
 101                 /*
 102                  * Extract the PFS from the link.  HAMMER will automatically
 103                  * convert @@PFS%05d links so if actually see one in that
 104                  * form the target PFS may not exist or may be corrupt.  But
 105                  * we can extract the PFS id anyway.
 106                  */
 107                 n = readlink(path, buf, sizeof(buf) - 1);
 108                 if (n < 0)
 109                         n = 0;
 110                 buf[n] = 0;
 111                 if (sscanf(buf, "@@PFS%d", &pfs->pfs_id) == 1) {
 112                         fd = open(dirpath, O_RDONLY);
 113                         goto done;
 114                 }
 115                 if (sscanf(buf, "@@%llx:%d", &dummy_tid, &pfs->pfs_id) == 2) {
 116                         fd = open(dirpath, O_RDONLY);
 117                         goto done;
 118                 }
 119         }
 120
 121         /*
 122          * Try to open the path and request the pfs_id that way.
 123          */
 124         fd = open(path, O_RDONLY);
 125         if (fd >= 0) {
 126                 pfs->pfs_id = -1;
 127                 ioctl(fd, HAMMERIOC_GET_PSEUDOFS, pfs);
 128                 if (pfs->pfs_id == -1) {
 129                         close(fd);
 130                         fd = -1;
 131                 }
 132         }
 133
 134         /*
 135          * Cleanup
 136          */
 137 done:
 138         if (fd < 0) {
 139                 fprintf(stderr, "Cannot access PFS %s: %s\n",
 140                         path, strerror(errno));
 141                 exit(1);
 142         }
 143         if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, pfs) < 0) {
 144                 fprintf(stderr, "Cannot access PFS %s: %s\n",
 145                         path, strerror(errno));
 146                 exit(1);
 147         }
 148         free(dirpath);
 149         return(fd);
 150 }
 151
 152 void
 153 relpfs(int fd, struct hammer_ioc_pseudofs_rw *pfs)
 154 {
 155         close(fd);
 156         if (pfs->ondisk) {
 157                 free(pfs->ondisk);
 158                 pfs->ondisk = NULL;
 159         }
 160 }
 161
 162 void
 163 hammer_cmd_pseudofs_status(char **av, int ac)
 164 {
 165         struct hammer_ioc_pseudofs_rw pfs;
 166         int i;
 167         int fd;
 168
 169         if (ac == 0)
 170                 pseudofs_usage(1);
 171
 172         for (i = 0; i < ac; ++i) {
 173                 printf("%s\t", av[i]);
 174                 fd = getpfs(&pfs, av[i]);
 175                 if (fd < 0 || ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) < 0) {
 176                         printf("Not a HAMMER root\n");
 177                 } else {
 178                         printf("PFS #%d {\n", pfs.pfs_id);
 179                         dump_pfsd(pfs.ondisk);
 180                         printf("}\n");
 181                 }
 182                 if (fd >= 0)
 183                         close(fd);
 184                 if (pfs.ondisk)
 185                         free(pfs.ondisk);
 186         }
 187 }
 188
 189 void
 190 hammer_cmd_pseudofs_create(char **av, int ac, int is_slave)
 191 {
 192         struct hammer_ioc_pseudofs_rw pfs;
 193         struct hammer_pseudofs_data pfsd;
 194         struct stat st;
 195         const char *path;
 196         char *dirpath;
 197         char *linkpath;
 198         int pfs_id;
 199         int fd;
 200         int error;
 201
 202         if (ac == 0)
 203                 pseudofs_usage(1);
 204         path = av[0];
 205         if (lstat(path, &st) == 0) {
 206                 fprintf(stderr, "Cannot create %s, file exists!\n", path);
 207                 exit(1);
 208         }
 209
 210         /*
 211          * Figure out the directory prefix, taking care of degenerate
 212          * cases.
 213          */
 214         dirpath = strdup(path);
 215         if (strrchr(dirpath, '/') != NULL) {
 216                 *strrchr(dirpath, '/') = 0;
 217                 if (dirpath[0] == 0) {
 218                         free(dirpath);
 219                         dirpath = strdup("/");
 220                 }
 221         } else {
 222                 free(dirpath);
 223                 dirpath = strdup(".");
 224         }
 225         fd = open(dirpath, O_RDONLY);
 226         if (fd < 0) {
 227                 fprintf(stderr, "Cannot open directory %s\n", dirpath);
 228                 exit(1);
 229         }
 230
 231         error = 0;
 232         for (pfs_id = 0; pfs_id < HAMMER_MAX_PFS; ++pfs_id) {
 233                 bzero(&pfs, sizeof(pfs));
 234                 bzero(&pfsd, sizeof(pfsd));
 235                 pfs.pfs_id = pfs_id;
 236                 pfs.ondisk = &pfsd;
 237                 pfs.bytes = sizeof(pfsd);
 238                 pfs.version = HAMMER_IOC_PSEUDOFS_VERSION;
 239                 if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) < 0) {
 240                         error = errno;
 241                         break;
 242                 }
 243         }
 244         if (pfs_id == HAMMER_MAX_PFS) {
 245                 fprintf(stderr, "Cannot create %s, all PFSs in use\n", path);
 246                 exit(1);
 247         }
 248         if (error != ENOENT) {
 249                 fprintf(stderr, "Cannot create %s, got %s during scan\n",
 250                         path, strerror(error));
 251                 exit(1);
 252         }
 253
 254         /*
 255          * Create the new PFS
 256          */
 257         printf("Creating PFS #%d\t", pfs_id);
 258         bzero(&pfsd, sizeof(pfsd));
 259         init_pfsd(&pfsd, is_slave);
 260         pfs.pfs_id = pfs_id;
 261         pfs.ondisk = &pfsd;
 262         pfs.bytes = sizeof(pfsd);
 263         pfs.version = HAMMER_IOC_PSEUDOFS_VERSION;
 264
 265         if (ioctl(fd, HAMMERIOC_SET_PSEUDOFS, &pfs) < 0) {
 266                 printf("failed: %s\n", strerror(errno));
 267         } else {
 268                 /* special symlink, must be exactly 10 characters */
 269                 asprintf(&linkpath, "@@PFS%05d", pfs_id);
 270                 if (symlink(linkpath, path) < 0) {
 271                         printf("failed: cannot create symlink: %s\n",
 272                                 strerror(errno));
 273                 } else {
 274                         printf("succeeded!\n");
 275                         hammer_cmd_pseudofs_update(av, ac);
 276                 }
 277         }
 278         close(fd);
 279 }
 280
 281 void
 282 hammer_cmd_pseudofs_destroy(char **av, int ac)
 283 {
 284         struct hammer_ioc_pseudofs_rw pfs;
 285         struct stat st;
 286         int fd;
 287         int i;
 288
 289         if (ac == 0)
 290                 pseudofs_usage(1);
 291         bzero(&pfs, sizeof(pfs));
 292         fd = getpfs(&pfs, av[0]);
 293
 294         if (pfs.pfs_id == 0) {
 295                 fprintf(stderr, "You cannot destroy PFS#0\n");
 296                 exit(1);
 297         }
 298         printf("You have requested that PFS#%d (%s) be destroyed\n",
 299                 pfs.pfs_id, pfs.ondisk->label);
 300         printf("This will irrevocably destroy all data on this PFS!!!!!\n");
 301         printf("Do you really want to do this? ");
 302         fflush(stdout);
 303         if (getyn() == 0) {
 304                 fprintf(stderr, "No action taken on PFS#%d\n", pfs.pfs_id);
 305                 exit(1);
 306         }
 307
 308         if ((pfs.ondisk->mirror_flags & HAMMER_PFSD_SLAVE) == 0) {
 309                 printf("This PFS is currently setup as a MASTER!\n");
 310                 printf("Are you absolutely sure you want to destroy it? ");
 311                 fflush(stdout);
 312                 if (getyn() == 0) {
 313                         fprintf(stderr, "No action taken on PFS#%d\n",
 314                                 pfs.pfs_id);
 315                         exit(1);
 316                 }
 317         }
 318
 319         printf("Destroying PFS #%d (%s) in ", pfs.pfs_id, pfs.ondisk->label);
 320         for (i = 5; i; --i) {
 321                 printf(" %d", i);
 322                 fflush(stdout);
 323                 sleep(1);
 324         }
 325         printf(".. starting destruction pass\n");
 326         fflush(stdout);
 327
 328         /*
 329          * Set the sync_beg_tid and sync_end_tid's to 1, once we start the
 330          * RMR the PFS is basically destroyed even if someone ^C's it.
 331          */
 332         pfs.ondisk->mirror_flags |= HAMMER_PFSD_SLAVE;
 333         pfs.ondisk->reserved01 = -1;
 334         pfs.ondisk->sync_beg_tid = 1;
 335         pfs.ondisk->sync_end_tid = 1;
 336
 337         if (ioctl(fd, HAMMERIOC_SET_PSEUDOFS, &pfs) < 0) {
 338                 fprintf(stderr, "Unable to update the PFS configuration: %s\n",
 339                         strerror(errno));
 340                 exit(1);
 341         }
 342
 343         /*
 344          * Ok, do it.  Remove the softlink on success.
 345          */
 346         if (ioctl(fd, HAMMERIOC_RMR_PSEUDOFS, &pfs) == 0) {
 347                 printf("pfs-destroy of PFS#%d succeeded!\n", pfs.pfs_id);
 348                 if (lstat(av[0], &st) == 0 && S_ISLNK(st.st_mode)) {
 349                         if (remove(av[0]) < 0) {
 350                                 fprintf(stderr, "Unable to remove softlink: %s "
 351                                         "(but the PFS has been destroyed)\n",
 352                                         av[0]);
 353                                 /* exit status 0 anyway */
 354                         }
 355                 }
 356         } else {
 357                 printf("pfs-destroy of PFS#%d failed: %s\n",
 358                         pfs.pfs_id, strerror(errno));
 359         }
 360 }
 361
 362 void
 363 hammer_cmd_pseudofs_upgrade(char **av, int ac)
 364 {
 365         struct hammer_ioc_pseudofs_rw pfs;
 366         int fd;
 367
 368         if (ac == 0)
 369                 pseudofs_usage(1);
 370         bzero(&pfs, sizeof(pfs));
 371         fd = getpfs(&pfs, av[0]);
 372
 373         if (pfs.pfs_id == 0) {
 374                 fprintf(stderr, "You cannot upgrade PFS#0"
 375                                 " (It should already be a master)\n");
 376                 exit(1);
 377         }
 378         if (ioctl(fd, HAMMERIOC_UPG_PSEUDOFS, &pfs) == 0) {
 379                 printf("pfs-upgrade of PFS#%d (%s) succeeded\n",
 380                         pfs.pfs_id, pfs.ondisk->label);
 381         } else {
 382                 fprintf(stderr, "pfs-upgrade of PFS#%d (%s) failed: %s\n",
 383                         pfs.pfs_id, pfs.ondisk->label, strerror(errno));
 384         }
 385 }
 386
 387 void
 388 hammer_cmd_pseudofs_downgrade(char **av, int ac)
 389 {
 390         struct hammer_ioc_pseudofs_rw pfs;
 391         int fd;
 392
 393         if (ac == 0)
 394                 pseudofs_usage(1);
 395         bzero(&pfs, sizeof(pfs));
 396         fd = getpfs(&pfs, av[0]);
 397
 398         if (pfs.pfs_id == 0) {
 399                 fprintf(stderr, "You cannot downgrade PFS#0\n");
 400                 exit(1);
 401         }
 402
 403         if (ioctl(fd, HAMMERIOC_DGD_PSEUDOFS, &pfs) == 0) {
 404                 printf("pfs-downgrade of PFS#%d (%s) succeeded\n",
 405                         pfs.pfs_id, pfs.ondisk->label);
 406         } else {
 407                 fprintf(stderr, "pfs-upgrade of PFS#%d (%s) failed: %s\n",
 408                         pfs.pfs_id, pfs.ondisk->label, strerror(errno));
 409         }
 410 }
 411
 412 void
 413 hammer_cmd_pseudofs_update(char **av, int ac)
 414 {
 415         struct hammer_ioc_pseudofs_rw pfs;
 416         int fd;
 417
 418         if (ac == 0)
 419                 pseudofs_usage(1);
 420         bzero(&pfs, sizeof(pfs));
 421         fd = getpfs(&pfs, av[0]);
 422
 423         printf("%s\n", av[0]);
 424         fflush(stdout);
 425
 426         if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) == 0) {
 427                 parse_pfsd_options(av + 1, ac - 1, pfs.ondisk);
 428                 if ((pfs.ondisk->mirror_flags & HAMMER_PFSD_SLAVE) &&
 429                     pfs.pfs_id == 0) {
 430                         printf("The real mount point cannot be made a PFS "
 431                                "slave, only PFS sub-directories can be made "
 432                                "slaves\n");
 433                         exit(1);
 434                 }
 435                 pfs.bytes = sizeof(*pfs.ondisk);
 436                 if (ioctl(fd, HAMMERIOC_SET_PSEUDOFS, &pfs) == 0) {
 437                         if (ioctl(fd, HAMMERIOC_GET_PSEUDOFS, &pfs) == 0) {
 438                                 dump_pfsd(pfs.ondisk);
 439                         } else {
 440                                 printf("Unable to retrieve pfs configuration "
 441                                         "after successful update: %s\n",
 442                                         strerror(errno));
 443                                 exit(1);
 444                         }
 445                 } else {
 446                         printf("Unable to adjust pfs configuration: %s\n",
 447                                 strerror(errno));
 448                         exit(1);
 449                 }
 450         }
 451 }
 452
 453 static void
 454 init_pfsd(hammer_pseudofs_data_t pfsd, int is_slave)
 455 {
 456         uint32_t status;
 457
 458         pfsd->sync_beg_tid = 1;
 459         pfsd->sync_end_tid = 1;
 460         pfsd->sync_beg_ts = 0;
 461         pfsd->sync_end_ts = 0;
 462         uuid_create(&pfsd->shared_uuid, &status);
 463         uuid_create(&pfsd->unique_uuid, &status);
 464         if (is_slave)
 465                 pfsd->mirror_flags |= HAMMER_PFSD_SLAVE;
 466 }
 467
 468 static
 469 void
 470 dump_pfsd(hammer_pseudofs_data_t pfsd)
 471 {
 472         u_int32_t status;
 473         char *str = NULL;
 474
 475         printf("    sync-beg-tid=0x%016llx\n", pfsd->sync_beg_tid);
 476         printf("    sync-end-tid=0x%016llx\n", pfsd->sync_end_tid);
 477         uuid_to_string(&pfsd->shared_uuid, &str, &status);
 478         printf("    shared-uuid=%s\n", str);
 479         uuid_to_string(&pfsd->unique_uuid, &str, &status);
 480         printf("    unique-uuid=%s\n", str);
 481         if (pfsd->mirror_flags & HAMMER_PFSD_SLAVE) {
 482                 printf("    slave\n");
 483         }
 484         printf("    label=\"%s\"\n", pfsd->label);
 485         if (pfsd->snapshots[0])
 486                 printf("    snapshots=\"%s\"\n", pfsd->snapshots);
 487         if (pfsd->mirror_flags & HAMMER_PFSD_SLAVE) {
 488                 printf("    operating as a SLAVE\n");
 489                 if (pfsd->snapshots[0] == 0)
 490                         printf("    snapshots directory not set for slave\n");
 491         } else {
 492                 printf("    operating as a MASTER\n");
 493                 if (pfsd->snapshots[0] == 0) {
 494                         printf("    snapshots dir for master "
 495                                "defaults to <fs>/snapshots\n");
 496                 }
 497         }
 498 }
 499
 500 static void
 501 parse_pfsd_options(char **av, int ac, hammer_pseudofs_data_t pfsd)
 502 {
 503         char *cmd;
 504         char *ptr;
 505         int len;
 506         uint32_t status;
 507
 508         while (ac) {
 509                 cmd = *av;
 510                 if ((ptr = strchr(cmd, '=')) != NULL)
 511                         *ptr++ = 0;
 512
 513                 /*
 514                  * Basic assignment value test
 515                  */
 516                 if (ptr == NULL) {
 517                         fprintf(stderr,
 518                                 "option %s requires an assignment\n",
 519                                 cmd);
 520                         exit(1);
 521                 }
 522
 523                 status = uuid_s_ok;
 524                 if (strcmp(cmd, "sync-beg-tid") == 0) {
 525                         pfsd->sync_beg_tid = strtoull(ptr, NULL, 16);
 526                 } else if (strcmp(cmd, "sync-end-tid") == 0) {
 527                         pfsd->sync_end_tid = strtoull(ptr, NULL, 16);
 528                 } else if (strcmp(cmd, "shared-uuid") == 0) {
 529                         uuid_from_string(ptr, &pfsd->shared_uuid, &status);
 530                 } else if (strcmp(cmd, "unique-uuid") == 0) {
 531                         uuid_from_string(ptr, &pfsd->unique_uuid, &status);
 532                 } else if (strcmp(cmd, "label") == 0) {
 533                         len = strlen(ptr);
 534                         if (ptr[0] == '"' && ptr[len-1] == '"') {
 535                                 ptr[len-1] = 0;
 536                                 ++ptr;
 537                         } else if (ptr[0] == '"') {
 538                                 fprintf(stderr,
 539                                         "option %s: malformed string\n",
 540                                         cmd);
 541                                 exit(1);
 542                         }
 543                         snprintf(pfsd->label, sizeof(pfsd->label), "%s", ptr);
 544                 } else if (strcmp(cmd, "snapshots") == 0) {
 545                         len = strlen(ptr);
 546                         if (ptr[0] != '/') {
 547                                 fprintf(stderr,
 548                                         "option %s: '%s' must be an "
 549                                         "absolute path\n", cmd, ptr);
 550                                 if (ptr[0] == 0) {
 551                                         fprintf(stderr,
 552                                                 "use 'snapshots-clear' "
 553                                                 "to unset snapshots dir\n");
 554                                 }
 555                                 exit(1);
 556                         }
 557                         if (len >= (int)sizeof(pfsd->snapshots)) {
 558                                 fprintf(stderr,
 559                                         "option %s: path too long, %d "
 560                                         "character limit\n", cmd, len);
 561                                 exit(1);
 562                         }
 563                         snprintf(pfsd->snapshots, sizeof(pfsd->snapshots),
 564                                  "%s", ptr);
 565                 } else if (strcmp(cmd, "snapshots-clear") == 0) {
 566                         pfsd->snapshots[0] = 0;
 567                 } else {
 568                         fprintf(stderr, "invalid option: %s\n", cmd);
 569                         exit(1);
 570                 }
 571                 if (status != uuid_s_ok) {
 572                         fprintf(stderr, "option %s: error parsing uuid %s\n",
 573                                 cmd, ptr);
 574                         exit(1);
 575                 }
 576                 --ac;
 577                 ++av;
 578         }
 579 }
 580
 581 static
 582 void
 583 pseudofs_usage(int code)
 584 {
 585         fprintf(stderr,
 586                 "hammer pfs-status <dirpath> ...\n"
 587                 "hammer pfs-master <dirpath> [options]\n"
 588                 "hammer pfs-slave <dirpath> [options]\n"
 589                 "hammer pfs-update <dirpath> [options]\n"
 590                 "hammer pfs-upgrade <dirpath>\n"
 591                 "hammer pfs-downgrade <dirpath>\n"
 592                 "hammer pfs-destroy <dirpath>\n"
 593                 "\n"
 594                 "options:\n"
 595                 "    sync-beg-tid=0x16llx\n"
 596                 "    sync-end-tid=0x16llx\n"
 597                 "    shared-uuid=0x16llx\n"
 598                 "    unique-uuid=0x16llx\n"
 599                 "    label=\"string\"\n"
 600                 "    snapshots=\"/path\"\n"
 601                 "    snapshots-clear\n"
 602         );
 603         exit(code);
 604 }
 605
 606 static
 607 int
 608 getyn(void)
 609 {
 610         char buf[256];
 611         int len;
 612
 613         if (fgets(buf, sizeof(buf), stdin) == NULL)
 614                 return(0);
 615         len = strlen(buf);
 616         while (len && (buf[len-1] == '\n' || buf[len-1] == '\r'))
 617                 --len;
 618         buf[len] = 0;
 619         if (strcmp(buf, "y") == 0 ||
 620             strcmp(buf, "yes") == 0 ||
 621             strcmp(buf, "Y") == 0 ||
 622             strcmp(buf, "YES") == 0) {
 623                 return(1);
 624         }
 625         return(0);
 626 }
 627