1 /*
2 * ismounted.c --- Check to see if the filesystem was mounted
3 *
4 * Copyright (C) 1995,1996,1997,1998,1999,2000 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 #if HAVE_ERRNO_H
17 #include <errno.h>
18 #endif
19 #include <fcntl.h>
20 #ifdef HAVE_LINUX_FD_H
21 #include <linux/fd.h>
22 #endif
23 #ifdef HAVE_MNTENT_H
24 #include <mntent.h>
25 #endif
26 #ifdef HAVE_GETMNTINFO
27 #include <paths.h>
28 #include <sys/param.h>
29 #include <sys/mount.h>
30 #endif /* HAVE_GETMNTINFO */
31 #include <string.h>
32 #include <sys/stat.h>
33
34 #include "ext2_fs.h"
35 #include "ext2fs.h"
36
37 #ifdef HAVE_MNTENT_H
38 /*
39 * Helper function which checks a file in /etc/mtab format to see if a
40 * filesystem is mounted. Returns an error if the file doesn't exist
41 * or can't be opened.
42 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags,char * mtpt,int mtlen)43 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
44 int *mount_flags, char *mtpt, int mtlen)
45 {
46 struct mntent *mnt;
47 struct stat st_buf;
48 errcode_t retval = 0;
49 dev_t file_dev=0, file_rdev=0;
50 ino_t file_ino=0;
51 FILE *f;
52 int fd;
53
54 *mount_flags = 0;
55 if ((f = setmntent (mtab_file, "r")) == NULL)
56 return errno;
57 if (stat(file, &st_buf) == 0) {
58 if (S_ISBLK(st_buf.st_mode)) {
59 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
60 file_rdev = st_buf.st_rdev;
61 #endif /* __GNU__ */
62 } else {
63 file_dev = st_buf.st_dev;
64 file_ino = st_buf.st_ino;
65 }
66 }
67 while ((mnt = getmntent (f)) != NULL) {
68 if (strcmp(file, mnt->mnt_fsname) == 0)
69 break;
70 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
71 if (S_ISBLK(st_buf.st_mode)) {
72 #ifndef __GNU__
73 if (file_rdev && (file_rdev == st_buf.st_rdev))
74 break;
75 #endif /* __GNU__ */
76 } else {
77 if (file_dev && ((file_dev == st_buf.st_dev) &&
78 (file_ino == st_buf.st_ino)))
79 break;
80 }
81 }
82 }
83
84 if (mnt == 0) {
85 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
86 /*
87 * Do an extra check to see if this is the root device. We
88 * can't trust /etc/mtab, and /proc/mounts will only list
89 * /dev/root for the root filesystem. Argh. Instead we
90 * check if the given device has the same major/minor number
91 * as the device that the root directory is on.
92 */
93 if (file_rdev && stat("/", &st_buf) == 0) {
94 if (st_buf.st_dev == file_rdev) {
95 *mount_flags = EXT2_MF_MOUNTED;
96 if (mtpt)
97 strncpy(mtpt, "/", mtlen);
98 goto is_root;
99 }
100 }
101 #endif /* __GNU__ */
102 goto errout;
103 }
104 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
105 /* Validate the entry in case /etc/mtab is out of date */
106 /*
107 * We need to be paranoid, because some broken distributions
108 * (read: Slackware) don't initialize /etc/mtab before checking
109 * all of the non-root filesystems on the disk.
110 */
111 if (stat(mnt->mnt_dir, &st_buf) < 0) {
112 retval = errno;
113 if (retval == ENOENT) {
114 #ifdef DEBUG
115 printf("Bogus entry in %s! (%s does not exist)\n",
116 mtab_file, mnt->mnt_dir);
117 #endif /* DEBUG */
118 retval = 0;
119 }
120 goto errout;
121 }
122 if (file_rdev && (st_buf.st_dev != file_rdev)) {
123 #ifdef DEBUG
124 printf("Bogus entry in %s! (%s not mounted on %s)\n",
125 mtab_file, file, mnt->mnt_dir);
126 #endif /* DEBUG */
127 goto errout;
128 }
129 #endif /* __GNU__ */
130 *mount_flags = EXT2_MF_MOUNTED;
131
132 #ifdef MNTOPT_RO
133 /* Check to see if the ro option is set */
134 if (hasmntopt(mnt, MNTOPT_RO))
135 *mount_flags |= EXT2_MF_READONLY;
136 #endif
137
138 if (mtpt)
139 strncpy(mtpt, mnt->mnt_dir, mtlen);
140 /*
141 * Check to see if we're referring to the root filesystem.
142 * If so, do a manual check to see if we can open /etc/mtab
143 * read/write, since if the root is mounted read/only, the
144 * contents of /etc/mtab may not be accurate.
145 */
146 if (!strcmp(mnt->mnt_dir, "/")) {
147 is_root:
148 #define TEST_FILE "/.ismount-test-file"
149 *mount_flags |= EXT2_MF_ISROOT;
150 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
151 if (fd < 0) {
152 if (errno == EROFS)
153 *mount_flags |= EXT2_MF_READONLY;
154 } else
155 close(fd);
156 (void) unlink(TEST_FILE);
157 }
158 retval = 0;
159 errout:
160 endmntent (f);
161 return retval;
162 }
163
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)164 static errcode_t check_mntent(const char *file, int *mount_flags,
165 char *mtpt, int mtlen)
166 {
167 errcode_t retval;
168
169 #ifdef DEBUG
170 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
171 mtpt, mtlen);
172 if (retval == 0)
173 return 0;
174 #endif /* DEBUG */
175 #ifdef __linux__
176 retval = check_mntent_file("/proc/mounts", file, mount_flags,
177 mtpt, mtlen);
178 if (retval == 0 && (*mount_flags != 0))
179 return 0;
180 #endif /* __linux__ */
181 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
182 #ifndef MOUNTED
183 #define MOUNTED _PATH_MOUNTED
184 #endif /* MOUNTED */
185 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
186 return retval;
187 #else
188 *mount_flags = 0;
189 return 0;
190 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
191 }
192
193 #else
194 #if defined(HAVE_GETMNTINFO)
195
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)196 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
197 char *mtpt, int mtlen)
198 {
199 struct statfs *mp;
200 int len, n;
201 const char *s1;
202 char *s2;
203
204 n = getmntinfo(&mp, MNT_NOWAIT);
205 if (n == 0)
206 return errno;
207
208 len = sizeof(_PATH_DEV) - 1;
209 s1 = file;
210 if (strncmp(_PATH_DEV, s1, len) == 0)
211 s1 += len;
212
213 *mount_flags = 0;
214 while (--n >= 0) {
215 s2 = mp->f_mntfromname;
216 if (strncmp(_PATH_DEV, s2, len) == 0) {
217 s2 += len - 1;
218 *s2 = 'r';
219 }
220 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
221 *mount_flags = EXT2_MF_MOUNTED;
222 break;
223 }
224 ++mp;
225 }
226 if (mtpt)
227 strncpy(mtpt, mp->f_mntonname, mtlen);
228 return 0;
229 }
230 #endif /* HAVE_GETMNTINFO */
231 #endif /* HAVE_MNTENT_H */
232
233 /*
234 * Check to see if we're dealing with the swap device.
235 */
is_swap_device(const char * file)236 static int is_swap_device(const char *file)
237 {
238 FILE *f;
239 char buf[1024], *cp;
240 dev_t file_dev;
241 struct stat st_buf;
242 int ret = 0;
243
244 file_dev = 0;
245 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
246 if ((stat(file, &st_buf) == 0) &&
247 S_ISBLK(st_buf.st_mode))
248 file_dev = st_buf.st_rdev;
249 #endif /* __GNU__ */
250
251 if (!(f = fopen("/proc/swaps", "r")))
252 return 0;
253 /* Skip the first line */
254 fgets(buf, sizeof(buf), f);
255 while (!feof(f)) {
256 if (!fgets(buf, sizeof(buf), f))
257 break;
258 if ((cp = strchr(buf, ' ')) != NULL)
259 *cp = 0;
260 if ((cp = strchr(buf, '\t')) != NULL)
261 *cp = 0;
262 if (strcmp(buf, file) == 0) {
263 ret++;
264 break;
265 }
266 #ifndef __GNU__
267 if (file_dev && (stat(buf, &st_buf) == 0) &&
268 S_ISBLK(st_buf.st_mode) &&
269 file_dev == st_buf.st_rdev) {
270 ret++;
271 break;
272 }
273 #endif /* __GNU__ */
274 }
275 fclose(f);
276 return ret;
277 }
278
279
280 /*
281 * ext2fs_check_mount_point() fills determines if the device is
282 * mounted or otherwise busy, and fills in mount_flags with one or
283 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
284 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
285 * non-NULL, the directory where the device is mounted is copied to
286 * where mtpt is pointing, up to mtlen characters.
287 */
288 #ifdef __TURBOC__
289 #pragma argsused
290 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)291 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
292 char *mtpt, int mtlen)
293 {
294 struct stat st_buf;
295 errcode_t retval = 0;
296 int fd;
297
298 if (is_swap_device(device)) {
299 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
300 strncpy(mtpt, "<swap>", mtlen);
301 } else {
302 #ifdef HAVE_MNTENT_H
303 retval = check_mntent(device, mount_flags, mtpt, mtlen);
304 #else
305 #ifdef HAVE_GETMNTINFO
306 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
307 #else
308 #ifdef __GNUC__
309 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
310 #endif
311 *mount_flags = 0;
312 #endif /* HAVE_GETMNTINFO */
313 #endif /* HAVE_MNTENT_H */
314 }
315 if (retval)
316 return retval;
317
318 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
319 if ((stat(device, &st_buf) != 0) ||
320 !S_ISBLK(st_buf.st_mode))
321 return 0;
322 fd = open(device, O_RDONLY | O_EXCL);
323 if (fd < 0) {
324 if (errno == EBUSY)
325 *mount_flags |= EXT2_MF_BUSY;
326 } else
327 close(fd);
328 #endif
329
330 return 0;
331 }
332
333 /*
334 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
335 * EXT2_MF_READONLY, and EXT2_MF_ROOT
336 *
337 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)338 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
339 {
340 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
341 }
342
343 #ifdef DEBUG
main(int argc,char ** argv)344 int main(int argc, char **argv)
345 {
346 int retval, mount_flags;
347 char mntpt[80];
348
349 if (argc < 2) {
350 fprintf(stderr, "Usage: %s device\n", argv[0]);
351 exit(1);
352 }
353
354 mntpt[0] = 0;
355 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
356 mntpt, sizeof(mntpt));
357 if (retval) {
358 com_err(argv[0], retval,
359 "while calling ext2fs_check_if_mounted");
360 exit(1);
361 }
362 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
363 if (mount_flags & EXT2_MF_BUSY)
364 printf("\t%s is apparently in use.\n", argv[1]);
365 if (mount_flags & EXT2_MF_MOUNTED)
366 printf("\t%s is mounted.\n", argv[1]);
367 if (mount_flags & EXT2_MF_SWAP)
368 printf("\t%s is a swap device.\n", argv[1]);
369 if (mount_flags & EXT2_MF_READONLY)
370 printf("\t%s is read-only.\n", argv[1]);
371 if (mount_flags & EXT2_MF_ISROOT)
372 printf("\t%s is the root filesystem.\n", argv[1]);
373 if (mntpt[0])
374 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
375 exit(0);
376 }
377 #endif /* DEBUG */
378