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 Library
8 * General Public License, version 2.
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_LINUX_LOOP_H
24 #include <linux/loop.h>
25 #include <sys/ioctl.h>
26 #ifdef HAVE_LINUX_MAJOR_H
27 #include <linux/major.h>
28 #endif /* HAVE_LINUX_MAJOR_H */
29 #endif /* HAVE_LINUX_LOOP_H */
30 #ifdef HAVE_MNTENT_H
31 #include <mntent.h>
32 #endif
33 #ifdef HAVE_GETMNTINFO
34 #include <paths.h>
35 #include <sys/param.h>
36 #include <sys/mount.h>
37 #endif /* HAVE_GETMNTINFO */
38 #include <string.h>
39 #include <sys/stat.h>
40
41 #include "ext2_fs.h"
42 #include "ext2fs.h"
43
44 /*
45 * Check to see if a regular file is mounted.
46 * If /etc/mtab/ is a symlink of /proc/mounts, you will need the following check
47 * because the name in /proc/mounts is a loopback device not a regular file.
48 */
check_loop_mounted(const char * mnt_fsname,dev_t mnt_rdev,dev_t file_dev,ino_t file_ino)49 static int check_loop_mounted(const char *mnt_fsname, dev_t mnt_rdev,
50 dev_t file_dev, ino_t file_ino)
51 {
52 #if defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H)
53 struct loop_info64 loopinfo;
54 int loop_fd, ret;
55
56 if (major(mnt_rdev) == LOOP_MAJOR) {
57 loop_fd = open(mnt_fsname, O_RDONLY);
58 if (loop_fd < 0)
59 return -1;
60
61 ret = ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo);
62 close(loop_fd);
63 if (ret < 0)
64 return -1;
65
66 if (file_dev == loopinfo.lo_device &&
67 file_ino == loopinfo.lo_inode)
68 return 1;
69 }
70 #endif /* defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) */
71 return 0;
72 }
73
74 #ifdef HAVE_SETMNTENT
75 /*
76 * Helper function which checks a file in /etc/mtab format to see if a
77 * filesystem is mounted. Returns an error if the file doesn't exist
78 * or can't be opened.
79 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags,char * mtpt,int mtlen)80 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
81 int *mount_flags, char *mtpt, int mtlen)
82 {
83 struct mntent *mnt;
84 struct stat st_buf;
85 errcode_t retval = 0;
86 dev_t file_dev=0, file_rdev=0;
87 ino_t file_ino=0;
88 FILE *f;
89 int fd;
90
91 *mount_flags = 0;
92 if ((f = setmntent (mtab_file, "r")) == NULL) {
93 if (errno == ENOENT) {
94 if (getenv("EXT2FS_NO_MTAB_OK"))
95 return 0;
96 else
97 return EXT2_ET_NO_MTAB_FILE;
98 }
99 return errno;
100 }
101 if (stat(file, &st_buf) == 0) {
102 if (S_ISBLK(st_buf.st_mode)) {
103 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
104 file_rdev = st_buf.st_rdev;
105 #endif /* __GNU__ */
106 } else {
107 file_dev = st_buf.st_dev;
108 file_ino = st_buf.st_ino;
109 }
110 }
111 while ((mnt = getmntent (f)) != NULL) {
112 if (mnt->mnt_fsname[0] != '/')
113 continue;
114 if (strcmp(file, mnt->mnt_fsname) == 0)
115 break;
116 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
117 if (S_ISBLK(st_buf.st_mode)) {
118 #ifndef __GNU__
119 if (file_rdev && (file_rdev == st_buf.st_rdev))
120 break;
121 if (check_loop_mounted(mnt->mnt_fsname,
122 st_buf.st_rdev, file_dev,
123 file_ino) == 1)
124 break;
125 #endif /* __GNU__ */
126 } else {
127 if (file_dev && ((file_dev == st_buf.st_dev) &&
128 (file_ino == st_buf.st_ino)))
129 break;
130 }
131 }
132 }
133
134 if (mnt == 0) {
135 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
136 /*
137 * Do an extra check to see if this is the root device. We
138 * can't trust /etc/mtab, and /proc/mounts will only list
139 * /dev/root for the root filesystem. Argh. Instead we
140 * check if the given device has the same major/minor number
141 * as the device that the root directory is on.
142 */
143 if (file_rdev && stat("/", &st_buf) == 0) {
144 if (st_buf.st_dev == file_rdev) {
145 *mount_flags = EXT2_MF_MOUNTED;
146 if (mtpt)
147 strncpy(mtpt, "/", mtlen);
148 goto is_root;
149 }
150 }
151 #endif /* __GNU__ */
152 goto errout;
153 }
154 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
155 /* Validate the entry in case /etc/mtab is out of date */
156 /*
157 * We need to be paranoid, because some broken distributions
158 * (read: Slackware) don't initialize /etc/mtab before checking
159 * all of the non-root filesystems on the disk.
160 */
161 if (stat(mnt->mnt_dir, &st_buf) < 0) {
162 retval = errno;
163 if (retval == ENOENT) {
164 #ifdef DEBUG
165 printf("Bogus entry in %s! (%s does not exist)\n",
166 mtab_file, mnt->mnt_dir);
167 #endif /* DEBUG */
168 retval = 0;
169 }
170 goto errout;
171 }
172 if (file_rdev && (st_buf.st_dev != file_rdev)) {
173 #ifdef DEBUG
174 printf("Bogus entry in %s! (%s not mounted on %s)\n",
175 mtab_file, file, mnt->mnt_dir);
176 #endif /* DEBUG */
177 goto errout;
178 }
179 #endif /* __GNU__ */
180 *mount_flags = EXT2_MF_MOUNTED;
181
182 #ifdef MNTOPT_RO
183 /* Check to see if the ro option is set */
184 if (hasmntopt(mnt, MNTOPT_RO))
185 *mount_flags |= EXT2_MF_READONLY;
186 #endif
187
188 if (mtpt)
189 strncpy(mtpt, mnt->mnt_dir, mtlen);
190 /*
191 * Check to see if we're referring to the root filesystem.
192 * If so, do a manual check to see if we can open /etc/mtab
193 * read/write, since if the root is mounted read/only, the
194 * contents of /etc/mtab may not be accurate.
195 */
196 if (!strcmp(mnt->mnt_dir, "/")) {
197 is_root:
198 #define TEST_FILE "/.ismount-test-file"
199 *mount_flags |= EXT2_MF_ISROOT;
200 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
201 if (fd < 0) {
202 if (errno == EROFS)
203 *mount_flags |= EXT2_MF_READONLY;
204 } else
205 close(fd);
206 (void) unlink(TEST_FILE);
207 }
208 retval = 0;
209 errout:
210 endmntent (f);
211 return retval;
212 }
213
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)214 static errcode_t check_mntent(const char *file, int *mount_flags,
215 char *mtpt, int mtlen)
216 {
217 errcode_t retval;
218
219 #ifdef DEBUG
220 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
221 mtpt, mtlen);
222 if (retval == 0)
223 return 0;
224 #endif /* DEBUG */
225 #ifdef __linux__
226 retval = check_mntent_file("/proc/mounts", file, mount_flags,
227 mtpt, mtlen);
228 if (retval == 0 && (*mount_flags != 0))
229 return 0;
230 #endif /* __linux__ */
231 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
232 #ifndef MOUNTED
233 #define MOUNTED _PATH_MOUNTED
234 #endif /* MOUNTED */
235 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
236 return retval;
237 #else
238 *mount_flags = 0;
239 return 0;
240 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
241 }
242
243 #else
244 #if defined(HAVE_GETMNTINFO)
245
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)246 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
247 char *mtpt, int mtlen)
248 {
249 struct statfs *mp;
250 int len, n;
251 const char *s1;
252 char *s2;
253
254 n = getmntinfo(&mp, MNT_NOWAIT);
255 if (n == 0)
256 return errno;
257
258 len = sizeof(_PATH_DEV) - 1;
259 s1 = file;
260 if (strncmp(_PATH_DEV, s1, len) == 0)
261 s1 += len;
262
263 *mount_flags = 0;
264 while (--n >= 0) {
265 s2 = mp->f_mntfromname;
266 if (strncmp(_PATH_DEV, s2, len) == 0) {
267 s2 += len - 1;
268 *s2 = 'r';
269 }
270 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
271 *mount_flags = EXT2_MF_MOUNTED;
272 break;
273 }
274 ++mp;
275 }
276 if (mtpt)
277 strncpy(mtpt, mp->f_mntonname, mtlen);
278 return 0;
279 }
280 #endif /* HAVE_GETMNTINFO */
281 #endif /* HAVE_SETMNTENT */
282
283 /*
284 * Check to see if we're dealing with the swap device.
285 */
is_swap_device(const char * file)286 static int is_swap_device(const char *file)
287 {
288 FILE *f;
289 char buf[1024], *cp;
290 dev_t file_dev;
291 struct stat st_buf;
292 int ret = 0;
293
294 file_dev = 0;
295 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
296 if ((stat(file, &st_buf) == 0) &&
297 S_ISBLK(st_buf.st_mode))
298 file_dev = st_buf.st_rdev;
299 #endif /* __GNU__ */
300
301 if (!(f = fopen("/proc/swaps", "r")))
302 return 0;
303 /* Skip the first line */
304 if (!fgets(buf, sizeof(buf), f))
305 goto leave;
306 if (*buf && strncmp(buf, "Filename\t", 9))
307 /* Linux <=2.6.19 contained a bug in the /proc/swaps
308 * code where the header would not be displayed
309 */
310 goto valid_first_line;
311
312 while (fgets(buf, sizeof(buf), f)) {
313 valid_first_line:
314 if ((cp = strchr(buf, ' ')) != NULL)
315 *cp = 0;
316 if ((cp = strchr(buf, '\t')) != NULL)
317 *cp = 0;
318 if (strcmp(buf, file) == 0) {
319 ret++;
320 break;
321 }
322 #ifndef __GNU__
323 if (file_dev && (stat(buf, &st_buf) == 0) &&
324 S_ISBLK(st_buf.st_mode) &&
325 file_dev == st_buf.st_rdev) {
326 ret++;
327 break;
328 }
329 #endif /* __GNU__ */
330 }
331
332 leave:
333 fclose(f);
334 return ret;
335 }
336
337
338 /*
339 * ext2fs_check_mount_point() fills determines if the device is
340 * mounted or otherwise busy, and fills in mount_flags with one or
341 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
342 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
343 * non-NULL, the directory where the device is mounted is copied to
344 * where mtpt is pointing, up to mtlen characters.
345 */
346 #ifdef __TURBOC__
347 #pragma argsused
348 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)349 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
350 char *mtpt, int mtlen)
351 {
352 errcode_t retval = 0;
353
354 if (is_swap_device(device)) {
355 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
356 strncpy(mtpt, "<swap>", mtlen);
357 } else {
358 #ifdef HAVE_SETMNTENT
359 retval = check_mntent(device, mount_flags, mtpt, mtlen);
360 #else
361 #ifdef HAVE_GETMNTINFO
362 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
363 #else
364 #ifdef __GNUC__
365 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
366 #endif
367 *mount_flags = 0;
368 #endif /* HAVE_GETMNTINFO */
369 #endif /* HAVE_SETMNTENT */
370 }
371 if (retval)
372 return retval;
373
374 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
375 {
376 struct stat st_buf;
377
378 if (stat(device, &st_buf) == 0 && S_ISBLK(st_buf.st_mode)) {
379 int fd = open(device, O_RDONLY | O_EXCL);
380
381 if (fd >= 0)
382 close(fd);
383 else if (errno == EBUSY)
384 *mount_flags |= EXT2_MF_BUSY;
385 }
386 }
387 #endif
388
389 return 0;
390 }
391
392 /*
393 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
394 * EXT2_MF_READONLY, and EXT2_MF_ROOT
395 *
396 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)397 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
398 {
399 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
400 }
401
402 #ifdef DEBUG
main(int argc,char ** argv)403 int main(int argc, char **argv)
404 {
405 int retval, mount_flags;
406 char mntpt[80];
407
408 if (argc < 2) {
409 fprintf(stderr, "Usage: %s device\n", argv[0]);
410 exit(1);
411 }
412
413 add_error_table(&et_ext2_error_table);
414 mntpt[0] = 0;
415 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
416 mntpt, sizeof(mntpt));
417 if (retval) {
418 com_err(argv[0], retval,
419 "while calling ext2fs_check_if_mounted");
420 exit(1);
421 }
422 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
423 if (mount_flags & EXT2_MF_BUSY)
424 printf("\t%s is apparently in use.\n", argv[1]);
425 if (mount_flags & EXT2_MF_MOUNTED)
426 printf("\t%s is mounted.\n", argv[1]);
427 if (mount_flags & EXT2_MF_SWAP)
428 printf("\t%s is a swap device.\n", argv[1]);
429 if (mount_flags & EXT2_MF_READONLY)
430 printf("\t%s is read-only.\n", argv[1]);
431 if (mount_flags & EXT2_MF_ISROOT)
432 printf("\t%s is the root filesystem.\n", argv[1]);
433 if (mntpt[0])
434 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
435 exit(0);
436 }
437 #endif /* DEBUG */
438