source: MondoRescue/branches/2.2.5/mindi-busybox/miscutils/mountpoint.c

/* vi: set sw=4 ts=4: */
/*
 * mountpoint implementation for busybox
 *
 * Copyright (C) 2005 Bernhard Fischer
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 *
 * Based on sysvinit's mountpoint
 */

#include "libbb.h"

int mountpoint_main(int argc, char **argv);
int mountpoint_main(int argc, char **argv)
{
    struct stat st;
    char *arg;
    int opt = getopt32(argv, "qdx");
#define OPT_q (1)
#define OPT_d (2)
#define OPT_x (4)

    if (optind != argc - 1)
        bb_show_usage();

    arg = argv[optind];

    if ( (opt & OPT_x && stat(arg, &st) == 0) || (lstat(arg, &st) == 0) ) {
        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;
            } else {
                if (opt & OPT_q)
                    putchar('\n');
                else
                    bb_error_msg("%s: not a block device", arg);
            }
            return EXIT_FAILURE;
        } else
        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 ret = (st_dev != st.st_dev) ||
                    (st_dev == st.st_dev && st_ino == st.st_ino);
                if (opt & OPT_d)
                    printf("%u:%u\n", major(st_dev), minor(st_dev));
                else if (!(opt & OPT_q))
                    printf("%s is %sa mountpoint\n", arg, ret?"":"not ");
                return !ret;
            }
        } else {
            if (!(opt & OPT_q))
                bb_error_msg("%s: not a directory", arg);
            return EXIT_FAILURE;
        }
    }
    if (!(opt & OPT_q))
        bb_perror_msg("%s", arg);
    return EXIT_FAILURE;
}