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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 | /* vi: set sw=4 ts=4: */ /* * Mini losetup implementation for busybox * * Copyright (C) 2002 Matt Kraai. * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ //config:config LOSETUP //config: bool "losetup (5.5 kb)" //config: default y //config: help //config: losetup is used to associate or detach a loop device with a regular //config: file or block device, and to query the status of a loop device. This //config: version does not currently support enabling data encryption. //applet:IF_LOSETUP(APPLET_NOEXEC(losetup, losetup, BB_DIR_SBIN, BB_SUID_DROP, losetup)) //kbuild:lib-$(CONFIG_LOSETUP) += losetup.o //usage:#define losetup_trivial_usage //usage: "[-rP] [-o OFS] {-f|LOOPDEV} FILE: associate loop devices\n" //usage: " losetup -c LOOPDEV: reread file size\n" //usage: " losetup -d LOOPDEV: disassociate\n" //usage: " losetup -a: show status\n" //usage: " losetup -f: show next free loop device" //usage:#define losetup_full_usage "\n\n" //usage: " -o OFS Start OFS bytes into FILE" //usage: "\n -P Scan for partitions" //usage: "\n -r Read-only" //usage: "\n -f Show/use next free loop device" //usage: //usage:#define losetup_notes_usage //usage: "One argument (losetup /dev/loop1) will display the current association\n" //usage: "(if any), or disassociate it (with -d). The display shows the offset\n" //usage: "and filename of the file the loop device is currently bound to.\n\n" //usage: "Two arguments (losetup /dev/loop1 file.img) create a new association,\n" //usage: "with optional partition scanning (creates /dev/loop1p1, /dev/loop1p2\n" //usage: "etc. with -P) and with an optional offset (-o 12345). Encryption is\n" //usage: "not yet supported. losetup -f will show the first free loop device\n\n" #include "libbb.h" /* 1048575 is a max possible minor number in Linux circa 2010 */ /* for now use something less extreme */ #define MAX_LOOP_NUM 1023 int losetup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int losetup_main(int argc UNUSED_PARAM, char **argv) { unsigned opt; char *opt_o; char dev[LOOP_NAMESIZE]; enum { OPT_c = (1 << 0), OPT_d = (1 << 1), OPT_P = (1 << 2), OPT_o = (1 << 3), OPT_f = (1 << 4), OPT_a = (1 << 5), OPT_r = (1 << 6), }; opt = getopt32(argv, "^" "cdPo:far" "\0" "?2:d--Pofar:a--Pofr", &opt_o); argv += optind; /* LOOPDEV */ if (!opt && argv[0] && !argv[1]) { char *s; s = query_loop(argv[0]); if (!s) bb_simple_perror_msg_and_die(argv[0]); printf("%s: %s\n", argv[0], s); if (ENABLE_FEATURE_CLEAN_UP) free(s); return EXIT_SUCCESS; } /* -c LOOPDEV */ if (opt == OPT_c && argv[0]) { int fd = xopen(argv[0], O_RDONLY); #ifndef LOOP_SET_CAPACITY # define LOOP_SET_CAPACITY 0x4C07 #endif xioctl(fd, LOOP_SET_CAPACITY, /*ignored:*/0); return EXIT_SUCCESS; } /* -d LOOPDEV */ if (opt == OPT_d && argv[0]) { if (del_loop(argv[0])) bb_simple_perror_msg_and_die(argv[0]); return EXIT_SUCCESS; } /* -a */ if (opt == OPT_a) { int n; for (n = 0; n < MAX_LOOP_NUM; n++) { char *s; sprintf(dev, LOOP_FORMAT, n); s = query_loop(dev); if (s) { printf("%s: %s\n", dev, s); free(s); } } return EXIT_SUCCESS; } /* contains -f */ if (opt & OPT_f) { char *s; int n; n = get_free_loop(); if (n == -1) bb_simple_error_msg_and_die("no free loop devices"); if (n < 0) /* n == -2: no /dev/loop-control, use legacy method */ n = 0; /* or: n >= 0: the number of next free loopdev, just verify it */ do { if (n > MAX_LOOP_NUM) bb_simple_error_msg_and_die("no free loop devices"); sprintf(dev, LOOP_FORMAT, n++); s = query_loop(dev); free(s); } while (s); /* now: dev is next free "/dev/loopN" */ if ((opt == OPT_f) && !argv[0]) { puts(dev); return EXIT_SUCCESS; } } /* [-rP] [-o OFS] {-f|LOOPDEV} FILE */ if (argv[0] && ((opt & OPT_f) || argv[1])) { unsigned long long offset = 0; char *d = dev; if (opt & OPT_o) offset = xatoull(opt_o); if (!(opt & OPT_f)) d = *argv++; if (argv[0]) { unsigned flags = (opt & OPT_r) ? BB_LO_FLAGS_READ_ONLY : 0; if (opt & OPT_P) { flags |= BB_LO_FLAGS_PARTSCAN; } if (set_loop(&d, argv[0], offset, 0, flags) < 0) bb_simple_perror_msg_and_die(argv[0]); return EXIT_SUCCESS; } } /* TODO: util-linux 2.28 shows this when run w/o params: * NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO * /dev/loop0 0 0 1 0 /PATH/TO/FILE 0 * * implemented by reading /sys: * * open("/sys/block", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3 * newfstatat(3, "loop0/loop/backing_file", {st_mode=S_IFREG|0444, st_size=4096, ...}, 0) = 0 * stat("/dev/loop0", {st_mode=S_IFBLK|0660, st_rdev=makedev(7, 0), ...}) = 0 * open("/sys/dev/block/7:0/loop/offset", O_RDONLY|O_CLOEXEC) = 5 * read(5, "0\n", 4096) = 2 * open("/sys/dev/block/7:0/loop/sizelimit", O_RDONLY|O_CLOEXEC) = 5 * read(5, "0\n", 4096) = 2 * open("/sys/dev/block/7:0/loop/offset", O_RDONLY|O_CLOEXEC) = 5 * read(5, "0\n", 4096) = 2 * open("/sys/dev/block/7:0/loop/autoclear", O_RDONLY|O_CLOEXEC) = 5 * read(5, "1\n", 4096) = 2 * open("/sys/dev/block/7:0/ro", O_RDONLY|O_CLOEXEC) = 5 * read(5, "0\n", 4096) = 2 * open("/sys/dev/block/7:0/loop/backing_file", O_RDONLY|O_CLOEXEC) = 5 * read(5, "/PATH/TO/FILE", 4096) = 37 * open("/sys/dev/block/7:0/loop/dio", O_RDONLY|O_CLOEXEC) = 5 * read(5, "0\n", 4096) = 2 */ bb_show_usage(); /* does not return */ /*return EXIT_FAILURE;*/ } |