LXR toybox/toys/other/mountpoint.c

   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 [-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
  24static 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
  32void 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