*
* 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: "[-r] [-o OFS] {-f|LOOPDEV} FILE - associate loop devices\n"
//usage: " losetup -d LOOPDEV - disassociate\n"
-//usage: " losetup -a - show status of all\n"
-//usage: " losetup -f - show next available"
+//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 -r Read-only"
-//usage: "\n -f Show/find first free loop device"
+//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"
#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)
{
OPT_r = (1 << 4), /* must be last */
};
- opt_complementary = "?2:d--ofar:a--ofr";
- opt = getopt32(argv, "do:far", &opt_o);
+ opt = getopt32(argv, "^" "do:far" "\0" "?2:d--ofar:a--ofr", &opt_o);
argv += optind;
/* LOOPDEV */
}
/* -d LOOPDEV */
- if (opt == OPT_d) {
+ 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 < 10; 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);
+ free(s);
}
}
return EXIT_SUCCESS;
int n = 0;
do {
- sprintf(dev, LOOP_FORMAT, n);
+ if (n > MAX_LOOP_NUM)
+ bb_error_msg_and_die("no free loop devices");
+ sprintf(dev, LOOP_FORMAT, n++);
s = query_loop(dev);
- if (s && ENABLE_FEATURE_CLEAN_UP)
- free(s);
+ free(s);
} while (s);
+ /* now: dev is next free "/dev/loopN" */
if ((opt == OPT_f) && !argv[0]) {
puts(dev);
return EXIT_SUCCESS;
unsigned long long offset = 0;
char *d = dev;
- if (opt == OPT_o)
+ if (opt & OPT_o)
offset = xatoull(opt_o);
- if (opt != OPT_f)
- d = *(argv++);
+ if (!(opt & OPT_f))
+ d = *argv++;
if (argv[0]) {
- if (set_loop(&d, argv[0], offset, (opt / OPT_r)) < 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;
}
}
- bb_show_usage();
- return EXIT_FAILURE;
+ /* 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;*/
}