+/* vi: set sw=4 ts=4: */
/*
* Mini losetup implementation for busybox
*
* Copyright (C) 2002 Matt Kraai.
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
+ * 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: select PLATFORM_LINUX
+//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
-#include <getopt.h>
-#include <stdlib.h>
+//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 "busybox.h"
+#include "libbb.h"
-int losetup_main (int argc, char **argv)
+/* 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)
{
- int offset = 0;
-
- /* This will need a "while(getopt()!=-1)" loop when we can have more than
- one option, but for now we can't. */
- switch(getopt(argc,argv, "do:")) {
- case 'd':
- /* detach takes exactly one argument */
- if(optind+1!=argc) bb_show_usage();
- if(!del_loop(argv[optind])) return EXIT_SUCCESS;
-die_failed:
- bb_perror_msg_and_die("%s",argv[optind]);
-
- case 'o':
- offset = bb_xparse_number (optarg, NULL);
- /* Fall through to do the losetup */
- case -1:
- /* losetup takes two argument:, loop_device and file */
- if(optind+2==argc) {
- if(set_loop(&argv[optind], argv[optind + 1], offset)>=0)
- return EXIT_SUCCESS;
- else goto die_failed;
- }
- if(optind+1==argc) {
- char *s=query_loop(argv[optind]);
- if (!s) goto die_failed;
- printf("%s: %s\n",argv[optind],s);
- if(ENABLE_FEATURE_CLEAN_UP) free(s);
- return EXIT_SUCCESS;
- }
- break;
- }
- bb_show_usage();
- return EXIT_FAILURE;
+ 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, 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;*/
}
projects / oweals / busybox.git / blobdiff