LXR busybox/miscutils/mountpoint.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * mountpoint implementation for busybox
   4 *
   5 * Copyright (C) 2005 Bernhard Reutner-Fischer
   6 *
   7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8 *
   9 * Based on sysvinit's mountpoint
  10 */
  11//config:config MOUNTPOINT
  12//config:       bool "mountpoint"
  13//config:       default y
  14//config:       help
  15//config:         mountpoint checks if the directory is a mountpoint.
  16
  17//applet:IF_MOUNTPOINT(APPLET(mountpoint, BB_DIR_BIN, BB_SUID_DROP))
  18
  19//kbuild:lib-$(CONFIG_MOUNTPOINT) += mountpoint.o
  20
  21//usage:#define mountpoint_trivial_usage
  22//usage:       "[-q] <[-dn] DIR | -x DEVICE>"
  23//usage:#define mountpoint_full_usage "\n\n"
  24//usage:       "Check if the directory is a mountpoint\n"
  25//usage:     "\n        -q      Quiet"
  26//usage:     "\n        -d      Print major/minor device number of the filesystem"
  27//usage:     "\n        -n      Print device name of the filesystem"
  28//usage:     "\n        -x      Print major/minor device number of the blockdevice"
  29//usage:
  30//usage:#define mountpoint_example_usage
  31//usage:       "$ mountpoint /proc\n"
  32//usage:       "/proc is not a mountpoint\n"
  33//usage:       "$ mountpoint /sys\n"
  34//usage:       "/sys is a mountpoint\n"
  35
  36#include "libbb.h"
  37
  38int mountpoint_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  39int mountpoint_main(int argc UNUSED_PARAM, char **argv)
  40{
  41        struct stat st;
  42        const char *msg;
  43        char *arg;
  44        int rc, opt;
  45
  46        opt_complementary = "=1"; /* must have one argument */
  47        opt = getopt32(argv, "qdxn");
  48#define OPT_q (1)
  49#define OPT_d (2)
  50#define OPT_x (4)
  51#define OPT_n (8)
  52        arg = argv[optind];
  53        msg = "%s";
  54
  55        rc = (opt & OPT_x) ? stat(arg, &st) : lstat(arg, &st);
  56        if (rc != 0)
  57                goto err;
  58
  59        if (opt & OPT_x) {
  60                if (S_ISBLK(st.st_mode)) {
  61                        printf("%u:%u\n", major(st.st_rdev),
  62                                                minor(st.st_rdev));
  63                        return EXIT_SUCCESS;
  64                }
  65                errno = 0; /* make perror_msg work as error_msg */
  66                msg = "%s: not a block device";
  67                goto err;
  68        }
  69
  70        errno = ENOTDIR;
  71        if (S_ISDIR(st.st_mode)) {
  72                dev_t st_dev = st.st_dev;
  73                ino_t st_ino = st.st_ino;
  74                char *p = xasprintf("%s/..", arg);
  75
  76                if (stat(p, &st) == 0) {
  77                        //int is_mnt = (st_dev != st.st_dev) || (st_dev == st.st_dev && st_ino == st.st_ino);
  78                        int is_not_mnt = (st_dev == st.st_dev) && (st_ino != st.st_ino);
  79
  80                        if (opt & OPT_d)
  81                                printf("%u:%u\n", major(st_dev), minor(st_dev));
  82                        if (opt & OPT_n) {
  83                                const char *d = find_block_device(arg);
  84                                /* name is undefined, but device is mounted -> anonymous superblock! */
  85                                /* happens with btrfs */
  86                                if (!d) {
  87                                        d = "UNKNOWN";
  88                                        /* TODO: iterate /proc/mounts, or /proc/self/mountinfo
  89                                         * to find out the device name */
  90                                }
  91                                printf("%s %s\n", d, arg);
  92                        }
  93                        if (!(opt & (OPT_q | OPT_d | OPT_n)))
  94                                printf("%s is %sa mountpoint\n", arg, is_not_mnt ? "not " : "");
  95                        return is_not_mnt;
  96                }
  97                arg = p;
  98                /* else: stat had set errno, just fall through */
  99        }
 100
 101 err:
 102        if (!(opt & OPT_q))
 103                bb_perror_msg(msg, arg);
 104        return EXIT_FAILURE;
 105}
 106