*
* 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
//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: "[-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/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"
//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 an optional offset (-o 12345). Encryption is not yet supported.\n"
-//usage: "losetup -f will show the first loop free loop device\n\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)
{
char *opt_o;
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 */
+ 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_complementary = "?2:d--ofar:a--ofr";
- opt = getopt32(argv, "do:far", &opt_o);
+ opt = getopt32(argv, "^" "cdPo:far" "\0" "?2:d--Pofar:a--Pofr", &opt_o);
argv += optind;
/* LOOPDEV */
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) {
+ 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;
/* contains -f */
if (opt & OPT_f) {
char *s;
- int n = 0;
+ 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 {
- sprintf(dev, LOOP_FORMAT, n);
+ if (n > MAX_LOOP_NUM)
+ bb_simple_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;
}
}
- /* [-r] [-o OFS] {-f|LOOPDEV} FILE */
+ /* [-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)
+ 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)
+ 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;
}
}
- 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;*/
}
projects / oweals / busybox.git / blobdiff