*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//config:config LOSETUP
+//config: bool "losetup (5.4 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
//usage:#define losetup_trivial_usage
-//usage: "[-o OFS] LOOPDEV FILE - associate loop devices\n"
+//usage: "[-r] [-o OFS] {-f|LOOPDEV} FILE - associate loop devices\n"
//usage: " losetup -d LOOPDEV - disassociate\n"
-//usage: " losetup [-f] - show"
+//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 -f Show first free loop device"
+//usage: "\n -r Read-only"
+//usage: "\n -f Show/use next free loop device"
//usage:
//usage:#define losetup_notes_usage
-//usage: "No arguments will display all current associations.\n"
//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"
#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;
- int n;
char *opt_o;
- unsigned long long offset = 0;
+ char dev[LOOP_NAMESIZE];
enum {
OPT_d = (1 << 0),
OPT_o = (1 << 1),
OPT_f = (1 << 2),
+ OPT_a = (1 << 3),
+ OPT_r = (1 << 4), /* must be last */
};
- /* max 2 args, all opts are mutually exclusive */
- opt_complementary = "?2:d--of:o--df:f--do";
- opt = getopt32(argv, "do:f", &opt_o);
+ opt = getopt32(argv, "^" "do:far" "\0" "?2:d--ofar:a--ofr", &opt_o);
argv += optind;
- if (opt == OPT_o)
- offset = xatoull(opt_o);
-
- if (opt == OPT_d) {
- /* -d BLOCKDEV */
- if (!argv[0] || argv[1])
- bb_show_usage();
- if (del_loop(argv[0]))
- bb_simple_perror_msg_and_die(argv[0]);
- return EXIT_SUCCESS;
- }
-
- if (argv[0]) {
+ /* LOOPDEV */
+ if (!opt && argv[0] && !argv[1]) {
char *s;
- if (opt == OPT_f) /* -f should not have arguments */
- bb_show_usage();
-
- if (argv[1]) {
- /* [-o OFS] BLOCKDEV FILE */
- if (set_loop(&argv[0], argv[1], offset) < 0)
- bb_simple_perror_msg_and_die(argv[0]);
- return EXIT_SUCCESS;
- }
- /* [-o OFS] BLOCKDEV */
s = query_loop(argv[0]);
if (!s)
bb_simple_perror_msg_and_die(argv[0]);
return EXIT_SUCCESS;
}
- /* [-o OFS|-f] with no params */
- n = 0;
- while (1) {
- char *s;
- char dev[LOOP_NAMESIZE];
-
- sprintf(dev, LOOP_FORMAT, n);
- s = query_loop(dev);
- n++;
- if (!s) {
- if (n > 9 && errno && errno != ENXIO)
- return EXIT_SUCCESS;
- if (opt == OPT_f) {
- puts(dev);
- return EXIT_SUCCESS;
- }
- } else {
- if (opt != OPT_f)
+ /* -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);
- if (ENABLE_FEATURE_CLEAN_UP)
free(s);
+ }
+ }
+ return EXIT_SUCCESS;
+ }
+
+ /* contains -f */
+ if (opt & OPT_f) {
+ char *s;
+ int n = 0;
+
+ do {
+ if (n > MAX_LOOP_NUM)
+ bb_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;
}
}
- return EXIT_SUCCESS;
+
+ /* [-r] [-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]) {
+ if (set_loop(&d, argv[0], offset, (opt & OPT_r) ? BB_LO_FLAGS_READ_ONLY : 0) < 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