release/src/router/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
  12 //usage:#define mountpoint_trivial_usage
  13 //usage:       "[-q] <[-dn] DIR | -x DEVICE>"
  14 //usage:#define mountpoint_full_usage "\n\n"
  15 //usage:       "Check if the directory is a mountpoint\n"
  16 //usage:     "\n        -q      Quiet"
  17 //usage:     "\n        -d      Print major/minor device number of the filesystem"
  18 //usage:     "\n        -n      Print device name of the filesystem"
  19 //usage:     "\n        -x      Print major/minor device number of the blockdevice"
  20 //usage:
  21 //usage:#define mountpoint_example_usage
  22 //usage:       "$ mountpoint /proc\n"
  23 //usage:       "/proc is not a mountpoint\n"
  24 //usage:       "$ mountpoint /sys\n"
  25 //usage:       "/sys is a mountpoint\n"
  26
  27 #include "libbb.h"
  28
  29 int mountpoint_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  30 int mountpoint_main(int argc UNUSED_PARAM, char **argv)
  31 {
  32         struct stat st;
  33         const char *msg;
  34         char *arg;
  35         int rc, opt;
  36
  37         opt_complementary = "=1"; /* must have one argument */
  38         opt = getopt32(argv, "qdxn");
  39 #define OPT_q (1)
  40 #define OPT_d (2)
  41 #define OPT_x (4)
  42 #define OPT_n (8)
  43         arg = argv[optind];
  44         msg = "%s";
  45
  46         rc = (opt & OPT_x) ? stat(arg, &st) : lstat(arg, &st);
  47         if (rc != 0)
  48                 goto err;
  49
  50         if (opt & OPT_x) {
  51                 if (S_ISBLK(st.st_mode)) {
  52                         printf("%u:%u\n", major(st.st_rdev),
  53                                                 minor(st.st_rdev));
  54                         return EXIT_SUCCESS;
  55                 }
  56                 errno = 0; /* make perror_msg work as error_msg */
  57                 msg = "%s: not a block device";
  58                 goto err;
  59         }
  60
  61         errno = ENOTDIR;
  62         if (S_ISDIR(st.st_mode)) {
  63                 dev_t st_dev = st.st_dev;
  64                 ino_t st_ino = st.st_ino;
  65                 char *p = xasprintf("%s/..", arg);
  66
  67                 if (stat(p, &st) == 0) {
  68                         //int is_mnt = (st_dev != st.st_dev) || (st_dev == st.st_dev && st_ino == st.st_ino);
  69                         int is_not_mnt = (st_dev == st.st_dev) && (st_ino != st.st_ino);
  70
  71                         if (opt & OPT_d)
  72                                 printf("%u:%u\n", major(st_dev), minor(st_dev));
  73                         if (opt & OPT_n) {
  74                                 const char *d = find_block_device(arg);
  75                                 /* name is undefined, but device is mounted -> anonymous superblock! */
  76                                 /* happens with btrfs */
  77                                 if (!d) {
  78                                         d = "UNKNOWN";
  79                                         /* TODO: iterate /proc/mounts, or /proc/self/mountinfo
  80                                          * to find out the device name */
  81                                 }
  82                                 printf("%s %s\n", d, arg);
  83                         }
  84                         if (!(opt & (OPT_q | OPT_d | OPT_n)))
  85                                 printf("%s is %sa mountpoint\n", arg, is_not_mnt ? "not " : "");
  86                         return is_not_mnt;
  87                 }
  88                 arg = p;
  89                 /* else: stat had set errno, just fall through */
  90         }
  91
  92  err:
  93         if (!(opt & OPT_q))
  94                 bb_perror_msg(msg, arg);
  95         return EXIT_FAILURE;
  96 }