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