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