source: MondoRescue/branches/3.3/mindi-busybox/util-linux/losetup.c@ 3790

/* 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.
 */

//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\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/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"

#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_d = (1 << 0),
        OPT_o = (1 << 1),
        OPT_f = (1 << 2),
        OPT_a = (1 << 3),
        OPT_r = (1 << 4), /* must be last */
    };

    opt_complementary = "?2:d--ofar:a--ofr";
    opt = getopt32(argv, "do:far", &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;
    }

    /* -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 = 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;
        }
    }

    /* [-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)) < 0)
                bb_simple_perror_msg_and_die(argv[0]);
            return EXIT_SUCCESS;
        }
    }

    bb_show_usage(); /* does not return */
    /*return EXIT_FAILURE;*/
}