util-linux/losetup.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini losetup implementation for busybox
   4  *
   5  * Copyright (C) 2002  Matt Kraai.
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 //usage:#define losetup_trivial_usage
  11 //usage:       "[-o OFS] LOOPDEV FILE - associate loop devices\n"
  12 //usage:       "        losetup -d LOOPDEV - disassociate\n"
  13 //usage:       "        losetup [-f] - show"
  14 //usage:#define losetup_full_usage "\n\n"
  15 //usage:       "Options:"
  16 //usage:     "\n        -o OFS  Start OFS bytes into FILE"
  17 //usage:     "\n        -f      Show first free loop device"
  18 //usage:
  19 //usage:#define losetup_notes_usage
  20 //usage:       "No arguments will display all current associations.\n"
  21 //usage:       "One argument (losetup /dev/loop1) will display the current association\n"
  22 //usage:       "(if any), or disassociate it (with -d). The display shows the offset\n"
  23 //usage:       "and filename of the file the loop device is currently bound to.\n\n"
  24 //usage:       "Two arguments (losetup /dev/loop1 file.img) create a new association,\n"
  25 //usage:       "with an optional offset (-o 12345). Encryption is not yet supported.\n"
  26 //usage:       "losetup -f will show the first loop free loop device\n\n"
  27
  28 #include "libbb.h"
  29
  30 int losetup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  31 int losetup_main(int argc UNUSED_PARAM, char **argv)
  32 {
  33         unsigned opt;
  34         int n;
  35         char *opt_o;
  36         unsigned long long offset = 0;
  37         enum {
  38                 OPT_d = (1 << 0),
  39                 OPT_o = (1 << 1),
  40                 OPT_f = (1 << 2),
  41         };
  42
  43         /* max 2 args, all opts are mutually exclusive */
  44         opt_complementary = "?2:d--of:o--df:f--do";
  45         opt = getopt32(argv, "do:f", &opt_o);
  46         argv += optind;
  47
  48         if (opt == OPT_o)
  49                 offset = xatoull(opt_o);
  50
  51         if (opt == OPT_d) {
  52                 /* -d BLOCKDEV */
  53                 if (!argv[0] || argv[1])
  54                         bb_show_usage();
  55                 if (del_loop(argv[0]))
  56                         bb_simple_perror_msg_and_die(argv[0]);
  57                 return EXIT_SUCCESS;
  58         }
  59
  60         if (argv[0]) {
  61                 char *s;
  62
  63                 if (opt == OPT_f) /* -f should not have arguments */
  64                         bb_show_usage();
  65
  66                 if (argv[1]) {
  67                         /* [-o OFS] BLOCKDEV FILE */
  68                         if (set_loop(&argv[0], argv[1], offset) < 0)
  69                                 bb_simple_perror_msg_and_die(argv[0]);
  70                         return EXIT_SUCCESS;
  71                 }
  72                 /* [-o OFS] BLOCKDEV */
  73                 s = query_loop(argv[0]);
  74                 if (!s)
  75                         bb_simple_perror_msg_and_die(argv[0]);
  76                 printf("%s: %s\n", argv[0], s);
  77                 if (ENABLE_FEATURE_CLEAN_UP)
  78                         free(s);
  79                 return EXIT_SUCCESS;
  80         }
  81
  82         /* [-o OFS|-f] with no params */
  83         n = 0;
  84         while (1) {
  85                 char *s;
  86                 char dev[LOOP_NAMESIZE];
  87
  88                 sprintf(dev, LOOP_FORMAT, n);
  89                 s = query_loop(dev);
  90                 n++;
  91                 if (!s) {
  92                         if (n > 9 && errno && errno != ENXIO)
  93                                 return EXIT_SUCCESS;
  94                         if (opt == OPT_f) {
  95                                 puts(dev);
  96                                 return EXIT_SUCCESS;
  97                         }
  98                 } else {
  99                         if (opt != OPT_f)
 100                                 printf("%s: %s\n", dev, s);
 101                         if (ENABLE_FEATURE_CLEAN_UP)
 102                                 free(s);
 103                 }
 104         }
 105         return EXIT_SUCCESS;
 106 }