1 /*
2 * ismounted.c --- Check to see if the filesystem was mounted
3 *
4 * Copyright (C) 1995,1996,1997,1998,1999,2000,2008 Theodore Ts'o.
5 *
6 * %Begin-Header%
7 * This file may be redistributed under the terms of the GNU Public
8 * License.
9 * %End-Header%
10 */
11
12 #include <stdio.h>
13 #if HAVE_UNISTD_H
14 #include <unistd.h>
15 #endif
16 #ifdef HAVE_STDLIB_H
17 #include <stdlib.h>
18 #endif
19 #if HAVE_ERRNO_H
20 #include <errno.h>
21 #endif
22 #include <fcntl.h>
23 #ifdef HAVE_LINUX_FD_H
24 #include <linux/fd.h>
25 #endif
26 #ifdef HAVE_MNTENT_H
27 #include <mntent.h>
28 #endif
29 #include <string.h>
30 #include <sys/stat.h>
31 #include <ctype.h>
32
33 #include "fsck.h"
34
35 /*
36 * ext2fs_check_if_mounted flags
37 */
38 #define MF_MOUNTED 1
39
40 #include "et/com_err.h"
41
42 #ifdef HAVE_SETMNTENT
skip_over_blank(char * cp)43 static char *skip_over_blank(char *cp)
44 {
45 while (*cp && isspace(*cp))
46 cp++;
47 return cp;
48 }
49
skip_over_word(char * cp)50 static char *skip_over_word(char *cp)
51 {
52 while (*cp && !isspace(*cp))
53 cp++;
54 return cp;
55 }
56
parse_word(char ** buf)57 static char *parse_word(char **buf)
58 {
59 char *word, *next;
60
61 word = *buf;
62 if (*word == 0)
63 return 0;
64
65 word = skip_over_blank(word);
66 next = skip_over_word(word);
67 if (*next)
68 *next++ = 0;
69 *buf = next;
70 return word;
71 }
72 #endif
73
74 /*
75 * Helper function which checks a file in /etc/mtab format to see if a
76 * filesystem is mounted. Returns an error if the file doesn't exist
77 * or can't be opened.
78 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags)79 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
80 int *mount_flags)
81 {
82 #ifdef HAVE_SETMNTENT
83 struct stat st_buf;
84 errcode_t retval = 0;
85 dev_t file_dev=0, file_rdev=0;
86 ino_t file_ino=0;
87 FILE *f;
88 char buf[1024], *device = 0, *mnt_dir = 0, *cp;
89
90 *mount_flags = 0;
91 if ((f = setmntent (mtab_file, "r")) == NULL)
92 return errno;
93 if (stat(file, &st_buf) == 0) {
94 if (S_ISBLK(st_buf.st_mode)) {
95 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
96 file_rdev = st_buf.st_rdev;
97 #endif /* __GNU__ */
98 } else {
99 file_dev = st_buf.st_dev;
100 file_ino = st_buf.st_ino;
101 }
102 }
103 while (1) {
104 if (!fgets(buf, sizeof(buf), f)) {
105 device = mnt_dir = 0;
106 break;
107 }
108 buf[sizeof(buf)-1] = 0;
109
110 cp = buf;
111 device = parse_word(&cp);
112 if (!device || *device == '#')
113 return 0; /* Ignore blank lines and comments */
114 mnt_dir = parse_word(&cp);
115
116 if (device[0] != '/')
117 continue;
118
119 if (strcmp(file, device) == 0)
120 break;
121 if (stat(device, &st_buf) == 0) {
122 if (S_ISBLK(st_buf.st_mode)) {
123 #ifndef __GNU__
124 if (file_rdev && (file_rdev == st_buf.st_rdev))
125 break;
126 #endif /* __GNU__ */
127 } else {
128 if (file_dev && ((file_dev == st_buf.st_dev) &&
129 (file_ino == st_buf.st_ino)))
130 break;
131 }
132 }
133 }
134
135 if (mnt_dir == 0) {
136 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
137 /*
138 * Do an extra check to see if this is the root device. We
139 * can't trust /etc/mtab, and /proc/mounts will only list
140 * /dev/root for the root filesystem. Argh. Instead we
141 * check if the given device has the same major/minor number
142 * as the device that the root directory is on.
143 */
144 if (file_rdev && (stat("/", &st_buf) == 0) &&
145 (st_buf.st_dev == file_rdev))
146 *mount_flags = MF_MOUNTED;
147 #endif /* __GNU__ */
148 goto errout;
149 }
150 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
151 /* Validate the entry in case /etc/mtab is out of date */
152 /*
153 * We need to be paranoid, because some broken distributions
154 * (read: Slackware) don't initialize /etc/mtab before checking
155 * all of the non-root filesystems on the disk.
156 */
157 if (stat(mnt_dir, &st_buf) < 0) {
158 retval = errno;
159 if (retval == ENOENT) {
160 #ifdef DEBUG
161 printf("Bogus entry in %s! (%s does not exist)\n",
162 mtab_file, mnt_dir);
163 #endif /* DEBUG */
164 retval = 0;
165 }
166 goto errout;
167 }
168 if (file_rdev && (st_buf.st_dev != file_rdev)) {
169 #ifdef DEBUG
170 printf("Bogus entry in %s! (%s not mounted on %s)\n",
171 mtab_file, file, mnt_dir);
172 #endif /* DEBUG */
173 goto errout;
174 }
175 #endif /* __GNU__ */
176 *mount_flags = MF_MOUNTED;
177
178 retval = 0;
179 errout:
180 endmntent (f);
181 return retval;
182 #else /* !HAVE_SETMNTENT */
183 return 0;
184 #endif /* HAVE_MNTENT_H */
185 }
186
is_mounted(const char * file)187 int is_mounted(const char *file)
188 {
189 errcode_t retval;
190 int mount_flags = 0;
191
192 #ifdef __linux__
193 retval = check_mntent_file("/proc/mounts", file, &mount_flags);
194 if (retval)
195 return 0;
196 if (mount_flags)
197 return 1;
198 #endif /* __linux__ */
199 retval = check_mntent_file("/etc/mtab", file, &mount_flags);
200 if (retval)
201 return 0;
202 return (mount_flags);
203 }
204
205 #ifdef DEBUG
main(int argc,char ** argv)206 int main(int argc, char **argv)
207 {
208 if (argc < 2) {
209 fprintf(stderr, "Usage: %s device\n", argv[0]);
210 exit(1);
211 }
212
213 if (is_mounted(argv[1]))
214 printf("\t%s is mounted.\n", argv[1]);
215 exit(0);
216 }
217 #endif /* DEBUG */
218