1/* mountpoint.c - Check if a directory is a mountpoint.
2 *
3 * Copyright 2012 Elie De Brauwer <eliedebrauwer@gmail.com>
4
5USE_MOUNTPOINT(NEWTOY(mountpoint, "<1qdx[-dx]", TOYFLAG_BIN))
6
7config 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
22static 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
30void 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