1 /* mountpoint.c - Check if a directory is a mountpoint.
2 *
3 * Copyright 2012 Elie De Brauwer <[email protected]>
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 (!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
37 if (lstat(arg, &st1)) (FLAG(q) ? die : perror_exit_raw)(arg);
38
39 if (FLAG(x)) {
40 if (!S_ISBLK(st1.st_mode)) die("block device");
41 if (!FLAG(q))
42 printf("%u:%u\n", dev_major(st1.st_rdev), dev_minor(st1.st_rdev));
43
44 return;
45 }
46
47 // TODO: a file can be a mountpoint for --bind mounts.
48 if (!S_ISDIR(st1.st_mode)) die("directory");
49
50 arg = xmprintf("%s/..", arg);
51 xstat(arg, &st2);
52 free(arg);
53
54 // If the device is different, it's a mount point. If the device _and_
55 // inode are the same, it's probably "/". This misses --bind mounts from
56 // elsewhere in the same filesystem, but so does the other one and in the
57 // absence of a spec I guess that's the expected behavior?
58 toys.exitval = !(st1.st_dev != st2.st_dev || st1.st_ino == st2.st_ino);
59 if (FLAG(d)) printf("%u:%u\n", dev_major(st1.st_dev), dev_minor(st1.st_dev));
60 else if (!FLAG(q))
61 printf("%s is %sa mountpoint\n", *toys.optargs, toys.exitval ? "not " : "");
62 }
63