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 [-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