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 (4.9 kb)"
13 //config: default y
14 //config: help
15 //config: mountpoint checks if the directory is a mountpoint.
16
17 //applet:IF_MOUNTPOINT(APPLET_NOEXEC(mountpoint, mountpoint, BB_DIR_BIN, BB_SUID_DROP, mountpoint))
18
19 //kbuild:lib-$(CONFIG_MOUNTPOINT) += mountpoint.o
20
21 //usage:#define mountpoint_trivial_usage
22 //usage: "[-q] { [-dn] DIR | -x DEVICE }"
23 //usage:#define mountpoint_full_usage "\n\n"
24 //usage: "Check if DIR is a mountpoint\n"
25 //usage: "\n -q Quiet"
26 //usage: "\n -d Print major:minor of the filesystem"
27 //usage: "\n -n Print device name of the filesystem"
28 //////// -n is not supported by util-linux-2.36.1 ^^^^^^^^^^^^^^^^^^
29 //usage: "\n -x Print major:minor of DEVICE"
30 //usage:
31 //usage:#define mountpoint_example_usage
32 //usage: "$ mountpoint /proc\n"
33 //usage: "/proc is not a mountpoint\n"
34 //usage: "$ mountpoint /sys\n"
35 //usage: "/sys is a mountpoint\n"
36
37 #include "libbb.h"
38
39 int mountpoint_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
mountpoint_main(int argc UNUSED_PARAM,char ** argv)40 int mountpoint_main(int argc UNUSED_PARAM, char **argv)
41 {
42 struct stat st;
43 const char *msg;
44 char *arg;
45 int rc, opt;
46
47 opt = getopt32(argv, "^" "qdxn" "\0" "=1");
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