source: MondoRescue/branches/3.2/mindi-busybox/miscutils/mountpoint.c@ 3232

/* vi: set sw=4 ts=4: */
/*
 * mountpoint implementation for busybox
 *
 * Copyright (C) 2005 Bernhard Reutner-Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Based on sysvinit's mountpoint
 */

//usage:#define mountpoint_trivial_usage
//usage:       "[-q] <[-dn] DIR | -x DEVICE>"
//usage:#define mountpoint_full_usage "\n\n"
//usage:       "Check if the directory is a mountpoint\n"
//usage:     "\n    -q  Quiet"
//usage:     "\n    -d  Print major/minor device number of the filesystem"
//usage:     "\n    -n  Print device name of the filesystem"
//usage:     "\n    -x  Print major/minor device number of the blockdevice"
//usage:
//usage:#define mountpoint_example_usage
//usage:       "$ mountpoint /proc\n"
//usage:       "/proc is not a mountpoint\n"
//usage:       "$ mountpoint /sys\n"
//usage:       "/sys is a mountpoint\n"

#include "libbb.h"

int mountpoint_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int mountpoint_main(int argc UNUSED_PARAM, char **argv)
{
    struct stat st;
    const char *msg;
    char *arg;
    int rc, opt;

    opt_complementary = "=1"; /* must have one argument */
    opt = getopt32(argv, "qdxn");
#define OPT_q (1)
#define OPT_d (2)
#define OPT_x (4)
#define OPT_n (8)
    arg = argv[optind];
    msg = "%s";

    rc = (opt & OPT_x) ? stat(arg, &st) : lstat(arg, &st);
    if (rc != 0)
        goto err;

    if (opt & OPT_x) {
        if (S_ISBLK(st.st_mode)) {
            printf("%u:%u\n", major(st.st_rdev),
                        minor(st.st_rdev));
            return EXIT_SUCCESS;
        }
        errno = 0; /* make perror_msg work as error_msg */
        msg = "%s: not a block device";
        goto err;
    }

    errno = ENOTDIR;
    if (S_ISDIR(st.st_mode)) {
        dev_t st_dev = st.st_dev;
        ino_t st_ino = st.st_ino;
        char *p = xasprintf("%s/..", arg);

        if (stat(p, &st) == 0) {
            //int is_mnt = (st_dev != st.st_dev) || (st_dev == st.st_dev && st_ino == st.st_ino);
            int is_not_mnt = (st_dev == st.st_dev) && (st_ino != st.st_ino);

            if (opt & OPT_d)
                printf("%u:%u\n", major(st_dev), minor(st_dev));
            if (opt & OPT_n) {
                const char *d = find_block_device(arg);
                /* name is undefined, but device is mounted -> anonymous superblock! */
                /* happens with btrfs */
                if (!d) {
                    d = "UNKNOWN";
                    /* TODO: iterate /proc/mounts, or /proc/self/mountinfo
                     * to find out the device name */
                }
                printf("%s %s\n", d, arg);
            }
            if (!(opt & (OPT_q | OPT_d | OPT_n)))
                printf("%s is %sa mountpoint\n", arg, is_not_mnt ? "not " : "");
            return is_not_mnt;
        }
        arg = p;
        /* else: stat had set errno, just fall through */
    }

 err:
    if (!(opt & OPT_q))
        bb_perror_msg(msg, arg);
    return EXIT_FAILURE;
}