1 /* mountpoint.c - Check if a directory is a mountpoint.
2 *
3 * Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
4
5 USE_MOUNTPOINT(NEWTOY(mountpoint, "<1qdx[-dx]", TOYFLAG_BIN))
6
7 config MOUNTPOINT
8 bool "mountpoint"
9 default y
10 help
11 usage: mountpoint [-qd] DIR
12 mountpoint [-qx] DEVICE
13
14 Check whether the directory or device is a mountpoint.
15
16 -q Be quiet, return zero if directory is a mountpoint
17 -d Print major/minor device number of the directory
18 -x Print major/minor device number of the block device
19 */
20
21 #define FOR_mountpoint
22 #include "toys.h"
23
die(char * gripe)24 static void die(char *gripe)
25 {
26 if (!(toys.optflags & FLAG_q)) printf("%s: not a %s\n", *toys.optargs, gripe);
27
28 toys.exitval++;
29 xexit();
30 }
31
mountpoint_main(void)32 void mountpoint_main(void)
33 {
34 struct stat st1, st2;
35 char *arg = *toys.optargs;
36 int quiet = toys.optflags & FLAG_q;
37
38 if (lstat(arg, &st1)) perror_exit_raw(arg);
39
40 if (toys.optflags & FLAG_x) {
41 if (S_ISBLK(st1.st_mode)) {
42 if (!quiet)
43 printf("%u:%u\n", dev_major(st1.st_rdev), dev_minor(st1.st_rdev));
44
45 return;
46 }
47 die("block device");
48 }
49
50 // TODO: Ignore the fact a file can be a mountpoint for --bind mounts.
51 if (!S_ISDIR(st1.st_mode)) die("directory");
52
53 arg = xmprintf("%s/..", arg);
54 xstat(arg, &st2);
55 if (CFG_TOYBOX_FREE) free(arg);
56
57 // If the device is different, it's a mount point. If the device _and_
58 // inode are the same, it's probably "/". This misses --bind mounts from
59 // elsewhere in the same filesystem, but so does the other one and in the
60 // absence of a spec I guess that's the expected behavior?
61 toys.exitval = !(st1.st_dev != st2.st_dev || st1.st_ino == st2.st_ino);
62 if (toys.optflags & FLAG_d)
63 printf("%u:%u\n", dev_major(st1.st_dev), dev_minor(st1.st_dev));
64 else if (!quiet)
65 printf("%s is %sa mountpoint\n", *toys.optargs, toys.exitval ? "not " : "");
66 }
67