sys-utils/losetup.c

   1 /*
   2  * Copyright (C) 2011 Karel Zak <kzak@redhat.com>
   3  * Originally from Ted's losetup.c
   4  *
   5  * losetup.c - setup and control loop devices
   6  */
   7 #include <assert.h>
   8 #include <stdio.h>
   9 #include <string.h>
  10 #include <errno.h>
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13 #include <sys/ioctl.h>
  14 #include <sys/stat.h>
  15 #include <inttypes.h>
  16 #include <getopt.h>
  17
  18 #include <libsmartcols.h>
  19
  20 #include "c.h"
  21 #include "nls.h"
  22 #include "strutils.h"
  23 #include "loopdev.h"
  24 #include "closestream.h"
  25 #include "optutils.h"
  26 #include "xalloc.h"
  27 #include "canonicalize.h"
  28
  29 enum {
  30         A_CREATE = 1,           /* setup a new device */
  31         A_DELETE,               /* delete given device(s) */
  32         A_DELETE_ALL,           /* delete all devices */
  33         A_SHOW,                 /* list devices */
  34         A_SHOW_ONE,             /* print info about one device */
  35         A_FIND_FREE,            /* find first unused */
  36         A_SET_CAPACITY,         /* set device capacity */
  37 };
  38
  39 enum {
  40         COL_NAME = 0,
  41         COL_AUTOCLR,
  42         COL_BACK_FILE,
  43         COL_BACK_INO,
  44         COL_BACK_MAJMIN,
  45         COL_MAJMIN,
  46         COL_OFFSET,
  47         COL_PARTSCAN,
  48         COL_RO,
  49         COL_SIZELIMIT,
  50 };
  51
  52 /* basic output flags */
  53 static int no_headings;
  54 static int raw;
  55
  56 struct colinfo {
  57         const char *name;
  58         double whint;
  59         int flags;
  60         const char *help;
  61 };
  62
  63 static struct colinfo infos[] = {
  64         [COL_AUTOCLR]     = { "AUTOCLEAR",    1, SCOLS_FL_RIGHT, N_("autoclear flag set")},
  65         [COL_BACK_FILE]   = { "BACK-FILE",  0.3, 0, N_("device backing file")},
  66         [COL_BACK_INO]    = { "BACK-INO",     4, SCOLS_FL_RIGHT, N_("backing file inode number")},
  67         [COL_BACK_MAJMIN] = { "BACK-MAJ:MIN", 6, 0, N_("backing file major:minor device number")},
  68         [COL_NAME]        = { "NAME",      0.25, 0, N_("loop device name")},
  69         [COL_OFFSET]      = { "OFFSET",       5, SCOLS_FL_RIGHT, N_("offset from the beginning")},
  70         [COL_PARTSCAN]    = { "PARTSCAN",     1, SCOLS_FL_RIGHT, N_("partscan flag set")},
  71         [COL_RO]          = { "RO",           1, SCOLS_FL_RIGHT, N_("read-only device")},
  72         [COL_SIZELIMIT]   = { "SIZELIMIT",    5, SCOLS_FL_RIGHT, N_("size limit of the file in bytes")},
  73         [COL_MAJMIN]      = { "MAJ:MIN",      3, 0, N_("loop device major:minor number")},
  74 };
  75
  76 #define NCOLS ARRAY_SIZE(infos)
  77
  78 static int columns[NCOLS] = {-1};
  79 static int ncolumns;
  80
  81 static int get_column_id(int num)
  82 {
  83         assert(ARRAY_SIZE(columns) == NCOLS);
  84         assert(num < ncolumns);
  85         assert(columns[num] < (int) NCOLS);
  86         return columns[num];
  87 }
  88
  89 static struct colinfo *get_column_info(int num)
  90 {
  91         return &infos[ get_column_id(num) ];
  92 }
  93
  94 static int column_name_to_id(const char *name, size_t namesz)
  95 {
  96         size_t i;
  97
  98         for (i = 0; i < NCOLS; i++) {
  99                 const char *cn = infos[i].name;
 100
 101                 if (!strncasecmp(name, cn, namesz) && !*(cn + namesz))
 102                         return i;
 103         }
 104         warnx(_("unknown column: %s"), name);
 105         return -1;
 106 }
 107
 108 static int printf_loopdev(struct loopdev_cxt *lc)
 109 {
 110         uint64_t x;
 111         dev_t dev = 0;
 112         ino_t ino = 0;
 113         char *fname = NULL;
 114         uint32_t type;
 115
 116         fname = loopcxt_get_backing_file(lc);
 117         if (!fname)
 118                 return -EINVAL;
 119
 120         if (loopcxt_get_backing_devno(lc, &dev) == 0)
 121                 loopcxt_get_backing_inode(lc, &ino);
 122
 123         if (!dev && !ino) {
 124                 /*
 125                  * Probably non-root user (no permissions to
 126                  * call LOOP_GET_STATUS ioctls).
 127                  */
 128                 printf("%s: []: (%s)",
 129                         loopcxt_get_device(lc), fname);
 130
 131                 if (loopcxt_get_offset(lc, &x) == 0 && x)
 132                                 printf(_(", offset %ju"), x);
 133
 134                 if (loopcxt_get_sizelimit(lc, &x) == 0 && x)
 135                                 printf(_(", sizelimit %ju"), x);
 136                 printf("\n");
 137                 return 0;
 138         }
 139
 140         printf("%s: [%04d]:%" PRIu64 " (%s)",
 141                 loopcxt_get_device(lc), (int) dev, ino, fname);
 142
 143         if (loopcxt_get_offset(lc, &x) == 0 && x)
 144                         printf(_(", offset %ju"), x);
 145
 146         if (loopcxt_get_sizelimit(lc, &x) == 0 && x)
 147                         printf(_(", sizelimit %ju"), x);
 148
 149         if (loopcxt_get_encrypt_type(lc, &type) == 0) {
 150                 const char *e = loopcxt_get_crypt_name(lc);
 151
 152                 if ((!e || !*e) && type == 1)
 153                         e = "XOR";
 154                 if (e && *e)
 155                         printf(_(", encryption %s (type %u)"), e, type);
 156         }
 157         printf("\n");
 158         return 0;
 159 }
 160
 161 static int show_all_loops(struct loopdev_cxt *lc, const char *file,
 162                           uint64_t offset, int flags)
 163 {
 164         struct stat sbuf, *st = &sbuf;
 165         char *cn_file = NULL;
 166
 167         if (loopcxt_init_iterator(lc, LOOPITER_FL_USED))
 168                 return -1;
 169
 170         if (!file || stat(file, st))
 171                 st = NULL;
 172
 173         while (loopcxt_next(lc) == 0) {
 174                 if (file) {
 175                         int used;
 176                         const char *bf = cn_file ? cn_file : file;
 177
 178                         used = loopcxt_is_used(lc, st, bf, offset, flags);
 179                         if (!used && !cn_file) {
 180                                 bf = cn_file = canonicalize_path(file);
 181                                 used = loopcxt_is_used(lc, st, bf, offset, flags);
 182                         }
 183                         if (!used)
 184                                 continue;
 185                 }
 186                 printf_loopdev(lc);
 187         }
 188         loopcxt_deinit_iterator(lc);
 189         free(cn_file);
 190         return 0;
 191 }
 192
 193 static int delete_loop(struct loopdev_cxt *lc)
 194 {
 195         if (loopcxt_delete_device(lc))
 196                 warn(_("%s: detach failed"), loopcxt_get_device(lc));
 197         else
 198                 return 0;
 199
 200         return -1;
 201 }
 202
 203 static int delete_all_loops(struct loopdev_cxt *lc)
 204 {
 205         int res = 0;
 206
 207         if (loopcxt_init_iterator(lc, LOOPITER_FL_USED))
 208                 return -1;
 209
 210         while (loopcxt_next(lc) == 0)
 211                 res += delete_loop(lc);
 212
 213         loopcxt_deinit_iterator(lc);
 214         return res;
 215 }
 216
 217 static int set_scols_data(struct loopdev_cxt *lc, struct libscols_line *ln)
 218 {
 219         int i;
 220
 221         for (i = 0; i < ncolumns; i++) {
 222                 const char *p = NULL;                   /* external data */
 223                 char *np = NULL;                        /* allocated here */
 224                 uint64_t x = 0;
 225
 226                 switch(get_column_id(i)) {
 227                 case COL_NAME:
 228                         p = loopcxt_get_device(lc);
 229                         break;
 230                 case COL_BACK_FILE:
 231                         p = loopcxt_get_backing_file(lc);
 232                         break;
 233                 case COL_OFFSET:
 234                         if (loopcxt_get_offset(lc, &x) == 0)
 235                                 xasprintf(&np, "%jd", x);
 236                         break;
 237                 case COL_SIZELIMIT:
 238                         if (loopcxt_get_sizelimit(lc, &x) == 0)
 239                                 xasprintf(&np, "%jd", x);
 240                         break;
 241                 case COL_BACK_MAJMIN:
 242                 {
 243                         dev_t dev = 0;
 244                         if (loopcxt_get_backing_devno(lc, &dev) == 0 && dev)
 245                                 xasprintf(&np, "%8u:%-3u", major(dev), minor(dev));
 246                         break;
 247                 }
 248                 case COL_MAJMIN:
 249                 {
 250                         struct stat st;
 251
 252                         if (loopcxt_get_device(lc)
 253                             && stat(loopcxt_get_device(lc), &st) == 0
 254                             && S_ISBLK(st.st_mode)
 255                             && major(st.st_rdev) == LOOPDEV_MAJOR)
 256                                 xasprintf(&np, "%3u:%-3u", major(st.st_rdev),
 257                                                            minor(st.st_rdev));
 258                         break;
 259                 }
 260                 case COL_BACK_INO:
 261                 {
 262                         ino_t ino = 0;
 263                         if (loopcxt_get_backing_inode(lc, &ino) == 0 && ino)
 264                                 xasprintf(&np, "%ju", ino);
 265                         break;
 266                 }
 267                 case COL_AUTOCLR:
 268                         p = loopcxt_is_autoclear(lc) ? "1" : "0";
 269                         break;
 270                 case COL_RO:
 271                         p = loopcxt_is_readonly(lc) ? "1" : "0";
 272                         break;
 273                 case COL_PARTSCAN:
 274                         p = loopcxt_is_partscan(lc) ? "1" : "0";
 275                         break;
 276                 default:
 277                         return -EINVAL;
 278                 }
 279
 280
 281                 if (p)
 282                         scols_line_set_data(ln, i, p);          /* calls strdup() */
 283                 else if (np)
 284                         scols_line_refer_data(ln, i, np);       /* only refers */
 285         }
 286
 287         return 0;
 288 }
 289
 290 static int show_table(struct loopdev_cxt *lc,
 291                       const char *file,
 292                       uint64_t offset,
 293                       int flags)
 294 {
 295         struct stat sbuf, *st = &sbuf;
 296         struct libscols_table *tb;
 297         struct libscols_line *ln;
 298         int i, rc = 0;
 299
 300         if (!(tb = scols_new_table()))
 301                 err(EXIT_FAILURE, _("failed to initialize output table"));
 302         scols_table_enable_raw(tb, raw);
 303         scols_table_enable_noheadings(tb, no_headings);
 304
 305         for (i = 0; i < ncolumns; i++) {
 306                 struct colinfo *ci = get_column_info(i);
 307
 308                 if (!scols_table_new_column(tb, ci->name, ci->whint, ci->flags))
 309                         err(EXIT_FAILURE, _("failed to initialize output column"));
 310         }
 311
 312         /* only one loopdev requested (already assigned to loopdev_cxt) */
 313         if (loopcxt_get_device(lc)) {
 314                 ln = scols_table_new_line(tb, NULL);
 315                 if (!ln)
 316                         err(EXIT_FAILURE, _("failed to initialize output line"));
 317                 rc = set_scols_data(lc, ln);
 318
 319         /* list all loopdevs */
 320         } else {
 321                 char *cn_file = NULL;
 322
 323                 rc = loopcxt_init_iterator(lc, LOOPITER_FL_USED);
 324                 if (rc)
 325                         goto done;
 326                 if (!file || stat(file, st))
 327                         st = NULL;
 328
 329                 while (loopcxt_next(lc) == 0) {
 330                         if (file) {
 331                                 int used;
 332                                 const char *bf = cn_file ? cn_file : file;
 333
 334                                 used = loopcxt_is_used(lc, st, bf, offset, flags);
 335                                 if (!used && !cn_file) {
 336                                         bf = cn_file = canonicalize_path(file);
 337                                         used = loopcxt_is_used(lc, st, bf, offset, flags);
 338                                 }
 339                                 if (!used)
 340                                         continue;
 341                         }
 342
 343                         ln = scols_table_new_line(tb, NULL);
 344                         if (!ln)
 345                                 err(EXIT_FAILURE, _("failed to initialize output column"));
 346                         rc = set_scols_data(lc, ln);
 347                         if (rc)
 348                                 break;
 349                 }
 350
 351                 loopcxt_deinit_iterator(lc);
 352                 free(cn_file);
 353         }
 354 done:
 355         if (rc == 0)
 356                 rc = scols_print_table(tb);
 357         scols_unref_table(tb);
 358         return rc;
 359 }
 360
 361 static void usage(FILE *out)
 362 {
 363         size_t i;
 364
 365         fputs(USAGE_HEADER, out);
 366
 367         fprintf(out,
 368               _(" %1$s [options] [<loopdev>]\n"
 369                 " %1$s [options] -f | <loopdev> <file>\n"),
 370                 program_invocation_short_name);
 371
 372         fputs(USAGE_OPTIONS, out);
 373         fputs(_(" -a, --all                     list all used devices\n"), out);
 374         fputs(_(" -d, --detach <loopdev>...     detach one or more devices\n"), out);
 375         fputs(_(" -D, --detach-all              detach all used devices\n"), out);
 376         fputs(_(" -f, --find                    find first unused device\n"), out);
 377         fputs(_(" -c, --set-capacity <loopdev>  resize the device\n"), out);
 378         fputs(_(" -j, --associated <file>       list all devices associated with <file>\n"), out);
 379
 380         fputs(USAGE_SEPARATOR, out);
 381
 382         fputs(_(" -o, --offset <num>            start at offset <num> into file\n"), out);
 383         fputs(_("     --sizelimit <num>         device is limited to <num> bytes of the file\n"), out);
 384         fputs(_(" -P, --partscan                create a partitioned loop device\n"), out);
 385         fputs(_(" -r, --read-only               set up a read-only loop device\n"), out);
 386         fputs(_("     --show                    print device name after setup (with -f)\n"), out);
 387         fputs(_(" -v, --verbose                 verbose mode\n"), out);
 388
 389         fputs(USAGE_SEPARATOR, out);
 390
 391         fputs(_(" -l, --list                    list info about all or specified (default)\n"), out);
 392         fputs(_(" -O, --output <cols>           specify columns to output for --list\n"), out);
 393         fputs(_(" -n, --noheadings              don't print headings for --list output\n"), out);
 394         fputs(_("     --raw                     use raw --list output format\n"), out);
 395
 396         fputs(USAGE_SEPARATOR, out);
 397         fputs(USAGE_HELP, out);
 398         fputs(USAGE_VERSION, out);
 399
 400         fputs(_("\nAvailable --list columns:\n"), out);
 401         for (i = 0; i < NCOLS; i++)
 402                 fprintf(out, " %12s  %s\n", infos[i].name, _(infos[i].help));
 403
 404         fprintf(out, USAGE_MAN_TAIL("losetup(8)"));
 405
 406         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
 407 }
 408
 409 static void warn_size(const char *filename, uint64_t size)
 410 {
 411         struct stat st;
 412
 413         if (!size) {
 414                 if (stat(filename, &st) || S_ISBLK(st.st_mode))
 415                         return;
 416                 size = st.st_size;
 417         }
 418
 419         if (size < 512)
 420                 warnx(_("%s: Warning: file is smaller than 512 bytes; the loop device "
 421                         "may be useless or invisible for system tools."),
 422                         filename);
 423         else if (size % 512)
 424                 warnx(_("%s: Warning: file does not fit into a 512-byte sector; "
 425                         "the end of the file will be ignored."),
 426                         filename);
 427 }
 428
 429 int main(int argc, char **argv)
 430 {
 431         struct loopdev_cxt lc;
 432         int act = 0, flags = 0, c;
 433         char *file = NULL;
 434         uint64_t offset = 0, sizelimit = 0;
 435         int res = 0, showdev = 0, lo_flags = 0;
 436         char *outarg = NULL;
 437         int list = 0;
 438
 439         enum {
 440                 OPT_SIZELIMIT = CHAR_MAX + 1,
 441                 OPT_SHOW,
 442                 OPT_RAW
 443         };
 444         static const struct option longopts[] = {
 445                 { "all", 0, 0, 'a' },
 446                 { "set-capacity", 1, 0, 'c' },
 447                 { "detach", 1, 0, 'd' },
 448                 { "detach-all", 0, 0, 'D' },
 449                 { "find", 0, 0, 'f' },
 450                 { "help", 0, 0, 'h' },
 451                 { "associated", 1, 0, 'j' },
 452                 { "list", 0, 0, 'l' },
 453                 { "noheadings", 0, 0, 'n' },
 454                 { "offset", 1, 0, 'o' },
 455                 { "output", 1, 0, 'O' },
 456                 { "sizelimit", 1, 0, OPT_SIZELIMIT },
 457                 { "partscan", 0, 0, 'P' },
 458                 { "read-only", 0, 0, 'r' },
 459                 { "raw", 0, 0, OPT_RAW },
 460                 { "show", 0, 0, OPT_SHOW },
 461                 { "verbose", 0, 0, 'v' },
 462                 { "version", 0, 0, 'V' },
 463                 { NULL, 0, 0, 0 }
 464         };
 465
 466         static const ul_excl_t excl[] = {       /* rows and cols in ASCII order */
 467                 { 'D','a','c','d','f','j' },
 468                 { 'D','c','d','f','l' },
 469                 { 'D','c','d','f','O' },
 470                 { 0 }
 471         };
 472         int excl_st[ARRAY_SIZE(excl)] = UL_EXCL_STATUS_INIT;
 473
 474         setlocale(LC_ALL, "");
 475         bindtextdomain(PACKAGE, LOCALEDIR);
 476         textdomain(PACKAGE);
 477         atexit(close_stdout);
 478
 479         if (loopcxt_init(&lc, 0))
 480                 err(EXIT_FAILURE, _("failed to initialize loopcxt"));
 481
 482         while ((c = getopt_long(argc, argv, "ac:d:Dfhj:lno:O:PrvV",
 483                                 longopts, NULL)) != -1) {
 484
 485                 err_exclusive_options(c, longopts, excl, excl_st);
 486
 487                 switch (c) {
 488                 case 'a':
 489                         act = A_SHOW;
 490                         break;
 491                 case 'c':
 492                         act = A_SET_CAPACITY;
 493                         if (!is_loopdev(optarg) ||
 494                             loopcxt_set_device(&lc, optarg))
 495                                 err(EXIT_FAILURE, _("%s: failed to use device"),
 496                                                 optarg);
 497                         break;
 498                 case 'r':
 499                         lo_flags |= LO_FLAGS_READ_ONLY;
 500                         break;
 501                 case 'd':
 502                         act = A_DELETE;
 503                         if (!is_loopdev(optarg) ||
 504                             loopcxt_set_device(&lc, optarg))
 505                                 err(EXIT_FAILURE, _("%s: failed to use device"),
 506                                                 optarg);
 507                         break;
 508                 case 'D':
 509                         act = A_DELETE_ALL;
 510                         break;
 511                 case 'f':
 512                         act = A_FIND_FREE;
 513                         break;
 514                 case 'h':
 515                         usage(stdout);
 516                         break;
 517                 case 'j':
 518                         act = A_SHOW;
 519                         file = optarg;
 520                         break;
 521                 case 'l':
 522                         list = 1;
 523                         break;
 524                 case 'n':
 525                         no_headings = 1;
 526                         break;
 527                 case OPT_RAW:
 528                         raw = 1;
 529                         break;
 530                 case 'o':
 531                         offset = strtosize_or_err(optarg, _("failed to parse offset"));
 532                         flags |= LOOPDEV_FL_OFFSET;
 533                         break;
 534                 case 'O':
 535                         outarg = optarg;
 536                         list = 1;
 537                         break;
 538                 case 'P':
 539                         lo_flags |= LO_FLAGS_PARTSCAN;
 540                         break;
 541                 case OPT_SHOW:
 542                         showdev = 1;
 543                         break;
 544                 case 'v':
 545                         break;
 546                 case 'V':
 547                         printf(UTIL_LINUX_VERSION);
 548                         return EXIT_SUCCESS;
 549                 case OPT_SIZELIMIT:                     /* --sizelimit */
 550                         sizelimit = strtosize_or_err(optarg, _("failed to parse size"));
 551                         flags |= LOOPDEV_FL_SIZELIMIT;
 552                         break;
 553                 default:
 554                         usage(stderr);
 555                 }
 556         }
 557
 558         /* default is --list --all */
 559         if (argc == 1) {
 560                 act = A_SHOW;
 561                 list = 1;
 562         }
 563
 564         /* default --list output columns */
 565         if (list && !ncolumns) {
 566                 columns[ncolumns++] = COL_NAME;
 567                 columns[ncolumns++] = COL_SIZELIMIT;
 568                 columns[ncolumns++] = COL_OFFSET;
 569                 columns[ncolumns++] = COL_AUTOCLR;
 570                 columns[ncolumns++] = COL_RO;
 571                 columns[ncolumns++] = COL_BACK_FILE;
 572         }
 573
 574         if (act == A_FIND_FREE && optind < argc) {
 575                 /*
 576                  * losetup -f <backing_file>
 577                  */
 578                 act = A_CREATE;
 579                 file = argv[optind++];
 580         }
 581
 582         if (list && !act && optind == argc)
 583                 /*
 584                  * losetup --list       defaults to --all
 585                  */
 586                 act = A_SHOW;
 587
 588         if (!act && optind + 1 == argc) {
 589                 /*
 590                  * losetup [--list] <device>
 591                  */
 592                 act = A_SHOW_ONE;
 593                 if (!is_loopdev(argv[optind]) ||
 594                     loopcxt_set_device(&lc, argv[optind]))
 595                         err(EXIT_FAILURE, _("%s: failed to use device"),
 596                                         argv[optind]);
 597                 optind++;
 598         }
 599         if (!act) {
 600                 /*
 601                  * losetup <loopdev> <backing_file>
 602                  */
 603                 act = A_CREATE;
 604
 605                 if (optind >= argc)
 606                         errx(EXIT_FAILURE, _("no loop device specified"));
 607                 /* don't use is_loopdev() here, the device does not have exist yet */
 608                 if (loopcxt_set_device(&lc, argv[optind]))
 609                         err(EXIT_FAILURE, _("%s: failed to use device"),
 610                                         argv[optind]);
 611                 optind++;
 612
 613                 if (optind >= argc)
 614                         errx(EXIT_FAILURE, _("no file specified"));
 615                 file = argv[optind++];
 616         }
 617
 618         if (act != A_CREATE &&
 619             (sizelimit || lo_flags || showdev))
 620                 errx(EXIT_FAILURE,
 621                         _("the options %s are allowed during loop device setup only"),
 622                         "--{sizelimit,read-only,show}");
 623
 624         if ((flags & LOOPDEV_FL_OFFSET) &&
 625             act != A_CREATE && (act != A_SHOW || !file))
 626                 errx(EXIT_FAILURE, _("the option --offset is not allowed in this context"));
 627
 628         if (outarg && string_add_to_idarray(outarg, columns, ARRAY_SIZE(columns),
 629                                          &ncolumns, column_name_to_id) < 0)
 630                 return EXIT_FAILURE;
 631
 632         switch (act) {
 633         case A_CREATE:
 634         {
 635                 int hasdev = loopcxt_has_device(&lc);
 636
 637                 if (hasdev && !is_loopdev(loopcxt_get_device(&lc)))
 638                         loopcxt_add_device(&lc);
 639                 do {
 640                         const char *errpre;
 641
 642                         /* Note that loopcxt_{find_unused,set_device}() resets
 643                          * loopcxt struct.
 644                          */
 645                         if (!hasdev && (res = loopcxt_find_unused(&lc))) {
 646                                 warnx(_("cannot find an unused loop device"));
 647                                 break;
 648                         }
 649                         if (flags & LOOPDEV_FL_OFFSET)
 650                                 loopcxt_set_offset(&lc, offset);
 651                         if (flags & LOOPDEV_FL_SIZELIMIT)
 652                                 loopcxt_set_sizelimit(&lc, sizelimit);
 653                         if (lo_flags)
 654                                 loopcxt_set_flags(&lc, lo_flags);
 655                         if ((res = loopcxt_set_backing_file(&lc, file))) {
 656                                 warn(_("%s: failed to use backing file"), file);
 657                                 break;
 658                         }
 659                         errno = 0;
 660                         res = loopcxt_setup_device(&lc);
 661                         if (res == 0)
 662                                 break;                  /* success */
 663                         if (errno == EBUSY && !hasdev)
 664                                 continue;
 665
 666                         /* errors */
 667                         errpre = hasdev && loopcxt_get_fd(&lc) < 0 ?
 668                                          loopcxt_get_device(&lc) : file;
 669                         warn(_("%s: failed to set up loop device"), errpre);
 670                         break;
 671                 } while (hasdev == 0);
 672
 673                 if (res == 0) {
 674                         if (showdev)
 675                                 printf("%s\n", loopcxt_get_device(&lc));
 676                         warn_size(file, sizelimit);
 677                 }
 678                 break;
 679         }
 680         case A_DELETE:
 681                 res = delete_loop(&lc);
 682                 while (optind < argc) {
 683                         if (!is_loopdev(argv[optind]) ||
 684                             loopcxt_set_device(&lc, argv[optind]))
 685                                 warn(_("%s: failed to use device"),
 686                                                 argv[optind]);
 687                         optind++;
 688                         res += delete_loop(&lc);
 689                 }
 690                 break;
 691         case A_DELETE_ALL:
 692                 res = delete_all_loops(&lc);
 693                 break;
 694         case A_FIND_FREE:
 695                 res = loopcxt_find_unused(&lc);
 696                 if (res)
 697                         warn(_("cannot find an unused loop device"));
 698                 else
 699                         printf("%s\n", loopcxt_get_device(&lc));
 700                 break;
 701         case A_SHOW:
 702                 if (list)
 703                         res = show_table(&lc, file, offset, flags);
 704                 else
 705                         res = show_all_loops(&lc, file, offset, flags);
 706                 break;
 707         case A_SHOW_ONE:
 708                 if (list)
 709                         res = show_table(&lc, NULL, 0, 0);
 710                 else
 711                         res = printf_loopdev(&lc);
 712                 if (res)
 713                         warn("%s", loopcxt_get_device(&lc));
 714                 break;
 715         case A_SET_CAPACITY:
 716                 res = loopcxt_set_capacity(&lc);
 717                 if (res)
 718                         warn(_("%s: set capacity failed"),
 719                                 loopcxt_get_device(&lc));
 720                 break;
 721         default:
 722                 usage(stderr);
 723                 break;
 724         }
 725
 726         loopcxt_deinit(&lc);
 727         return res ? EXIT_FAILURE : EXIT_SUCCESS;
 728 }
 729