src/mountpoint.c

   1 /*
   2  * mountpoint   See if a directory is a mountpoint.
   3  *
   4  * Author:      Miquel van Smoorenburg.
   5  *
   6  * Version:     @(#)mountpoint  2.85-12  17-Mar-2004     miquels@cistron.nl
   7  *
   8  *              This file is part of the sysvinit suite,
   9  *              Copyright (C) 1991-2004 Miquel van Smoorenburg.
  10  *
  11  *              This program is free software; you can redistribute it and/or modify
  12  *              it under the terms of the GNU General Public License as published by
  13  *              the Free Software Foundation; either version 2 of the License, or
  14  *              (at your option) any later version.
  15  *
  16  *              This program is distributed in the hope that it will be useful,
  17  *              but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  *              MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  *              GNU General Public License for more details.
  20  *
  21  *              You should have received a copy of the GNU General Public License
  22  *              along with this program; if not, write to the Free Software
  23  *              Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <sys/stat.h>
  27 #include <unistd.h>
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <errno.h>
  31 #include <stdarg.h>
  32 #include <getopt.h>
  33 #include <stdio.h>
  34
  35 int dostat(char *path, struct stat *st, int do_lstat, int quiet)
  36 {
  37         int             n;
  38
  39         if (do_lstat)
  40                 n = lstat(path, st);
  41         else
  42                 n = stat(path, st);
  43
  44         if (n != 0) {
  45                 if (!quiet)
  46                         fprintf(stderr, "mountpoint: %s: %s\n", path,
  47                                 strerror(errno));
  48                 return -1;
  49         }
  50         return 0;
  51 }
  52
  53 void usage(void) {
  54         fprintf(stderr, "Usage: mountpoint [-q] [-d] [-x] path\n");
  55         exit(1);
  56 }
  57
  58 int main(int argc, char **argv)
  59 {
  60         struct stat     st, st2;
  61         char            buf[256];
  62         char            *path;
  63         int             quiet = 0;
  64         int             showdev = 0;
  65         int             xdev = 0;
  66         int             c, r;
  67
  68         while ((c = getopt(argc, argv, "dqx")) != EOF) switch(c) {
  69                 case 'd':
  70                         showdev = 1;
  71                         break;
  72                 case 'q':
  73                         quiet = 1;
  74                         break;
  75                 case 'x':
  76                         xdev = 1;
  77                         break;
  78                 default:
  79                         usage();
  80                         break;
  81         }
  82         if (optind != argc - 1) usage();
  83         path = argv[optind];
  84
  85         if (dostat(path, &st, !xdev, quiet) < 0)
  86                 return 1;
  87
  88         if (xdev) {
  89 #ifdef __linux__
  90                 if (!S_ISBLK(st.st_mode))
  91 #else
  92                 if (!S_ISBLK(st.st_mode) && !S_ISCHR(st.st_mode))
  93 #endif
  94                 {
  95                         if (quiet)
  96                                 printf("\n");
  97                         else
  98                         fprintf(stderr, "mountpoint: %s: not a block device\n",
  99                                 path);
 100                         return 1;
 101                 }
 102                 printf("%u:%u\n", major(st.st_rdev), minor(st.st_rdev));
 103                 return 0;
 104         }
 105
 106         if (!S_ISDIR(st.st_mode)) {
 107                 if (!quiet)
 108                         fprintf(stderr, "mountpoint: %s: not a directory\n",
 109                                 path);
 110                 return 1;
 111         }
 112
 113         memset(buf, 0, sizeof(buf));
 114         strncpy(buf, path, sizeof(buf) - 4);
 115         strcat(buf, "/..");
 116         if (dostat(buf, &st2, 0, quiet) < 0)
 117                 return 1;
 118
 119         r = (st.st_dev != st2.st_dev) ||
 120             (st.st_dev == st2.st_dev && st.st_ino == st2.st_ino);
 121
 122         if (!quiet && !showdev)
 123                 printf("%s is %sa mountpoint\n", path, r ? "" : "not ");
 124         if (showdev)
 125                 printf("%u:%u\n", major(st.st_dev), minor(st.st_dev));
 126
 127         return r ? 0 : 1;
 128 }