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 /* define BSD_SOURCE to make sure we get the major() macro */
13 #ifndef _BSD_SOURCE
14 #define _BSD_SOURCE
15 #endif
16 #ifndef _DEFAULT_SOURCE
17 #define _DEFAULT_SOURCE /* since glibc 2.20 _SVID_SOURCE is deprecated */
18 #endif
19
20 #include "config.h"
21 #include <stdio.h>
22 #if HAVE_UNISTD_H
23 #include <unistd.h>
24 #endif
25 #if HAVE_ERRNO_H
26 #include <errno.h>
27 #endif
28 #include <fcntl.h>
29 #ifdef HAVE_LINUX_FD_H
30 #include <linux/fd.h>
31 #endif
32 #ifdef HAVE_LINUX_LOOP_H
33 #include <linux/loop.h>
34 #include <sys/ioctl.h>
35 #ifdef HAVE_LINUX_MAJOR_H
36 #include <linux/major.h>
37 #endif /* HAVE_LINUX_MAJOR_H */
38 #endif /* HAVE_LINUX_LOOP_H */
39 #ifdef HAVE_MNTENT_H
40 #include <mntent.h>
41 #endif
42 #ifdef HAVE_GETMNTINFO
43 #include <paths.h>
44 #include <sys/param.h>
45 #include <sys/mount.h>
46 #endif /* HAVE_GETMNTINFO */
47 #include <string.h>
48 #include <sys/stat.h>
49 #if HAVE_SYS_TYPES_H
50 #include <sys/types.h>
51 #endif
52 #ifdef HAVE_SYS_SYSMACROS_H
53 #include <sys/sysmacros.h>
54 #endif
55
56 #include "ext2_fs.h"
57 #include "ext2fs.h"
58
59 #ifdef HAVE_SETMNTENT
60 /*
61 * Check to see if a regular file is mounted.
62 * If /etc/mtab/ is a symlink of /proc/mounts, you will need the following check
63 * because the name in /proc/mounts is a loopback device not a regular file.
64 */
check_loop_mounted(const char * mnt_fsname,dev_t mnt_rdev,dev_t file_dev,ino_t file_ino)65 static int check_loop_mounted(const char *mnt_fsname, dev_t mnt_rdev,
66 dev_t file_dev, ino_t file_ino)
67 {
68 #if defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H)
69 struct loop_info64 loopinfo;
70 int loop_fd, ret;
71
72 if (major(mnt_rdev) == LOOP_MAJOR) {
73 loop_fd = open(mnt_fsname, O_RDONLY);
74 if (loop_fd < 0)
75 return -1;
76
77 ret = ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo);
78 close(loop_fd);
79 if (ret < 0)
80 return -1;
81
82 if (file_dev == loopinfo.lo_device &&
83 file_ino == loopinfo.lo_inode)
84 return 1;
85 }
86 #endif /* defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) */
87 return 0;
88 }
89
90 /*
91 * Helper function which checks a file in /etc/mtab format to see if a
92 * filesystem is mounted. Returns an error if the file doesn't exist
93 * or can't be opened.
94 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags,char * mtpt,int mtlen)95 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
96 int *mount_flags, char *mtpt, int mtlen)
97 {
98 struct mntent *mnt;
99 struct stat st_buf;
100 errcode_t retval = 0;
101 dev_t file_dev=0, file_rdev=0;
102 ino_t file_ino=0;
103 FILE *f;
104 int fd;
105
106 *mount_flags = 0;
107
108 if ((f = setmntent (mtab_file, "r")) == NULL) {
109 if (errno == ENOENT) {
110 if (getenv("EXT2FS_NO_MTAB_OK"))
111 return 0;
112 else
113 return EXT2_ET_NO_MTAB_FILE;
114 }
115 return errno;
116 }
117 if (stat(file, &st_buf) == 0) {
118 if (S_ISBLK(st_buf.st_mode)) {
119 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
120 file_rdev = st_buf.st_rdev;
121 #endif /* __GNU__ */
122 } else {
123 file_dev = st_buf.st_dev;
124 file_ino = st_buf.st_ino;
125 }
126 }
127 while ((mnt = getmntent (f)) != NULL) {
128 if (mnt->mnt_fsname[0] != '/')
129 continue;
130 if (strcmp(file, mnt->mnt_fsname) == 0)
131 break;
132 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
133 if (S_ISBLK(st_buf.st_mode)) {
134 #ifndef __GNU__
135 if (file_rdev && (file_rdev == st_buf.st_rdev))
136 break;
137 if (check_loop_mounted(mnt->mnt_fsname,
138 st_buf.st_rdev, file_dev,
139 file_ino) == 1)
140 break;
141 #endif /* __GNU__ */
142 } else {
143 if (file_dev && ((file_dev == st_buf.st_dev) &&
144 (file_ino == st_buf.st_ino)))
145 break;
146 }
147 }
148 }
149
150 if (mnt == 0) {
151 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
152 /*
153 * Do an extra check to see if this is the root device. We
154 * can't trust /etc/mtab, and /proc/mounts will only list
155 * /dev/root for the root filesystem. Argh. Instead we
156 * check if the given device has the same major/minor number
157 * as the device that the root directory is on.
158 */
159 if (file_rdev && stat("/", &st_buf) == 0) {
160 if (st_buf.st_dev == file_rdev) {
161 *mount_flags = EXT2_MF_MOUNTED;
162 if (mtpt)
163 strncpy(mtpt, "/", mtlen);
164 goto is_root;
165 }
166 }
167 #endif /* __GNU__ */
168 goto errout;
169 }
170 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
171 /* Validate the entry in case /etc/mtab is out of date */
172 /*
173 * We need to be paranoid, because some broken distributions
174 * (read: Slackware) don't initialize /etc/mtab before checking
175 * all of the non-root filesystems on the disk.
176 */
177 if (stat(mnt->mnt_dir, &st_buf) < 0) {
178 retval = errno;
179 if (retval == ENOENT) {
180 #ifdef DEBUG
181 printf("Bogus entry in %s! (%s does not exist)\n",
182 mtab_file, mnt->mnt_dir);
183 #endif /* DEBUG */
184 retval = 0;
185 }
186 goto errout;
187 }
188 if (file_rdev && (st_buf.st_dev != file_rdev)) {
189 #ifdef DEBUG
190 printf("Bogus entry in %s! (%s not mounted on %s)\n",
191 mtab_file, file, mnt->mnt_dir);
192 #endif /* DEBUG */
193 goto errout;
194 }
195 #endif /* __GNU__ */
196 *mount_flags = EXT2_MF_MOUNTED;
197
198 #ifdef MNTOPT_RO
199 /* Check to see if the ro option is set */
200 if (hasmntopt(mnt, MNTOPT_RO))
201 *mount_flags |= EXT2_MF_READONLY;
202 #endif
203
204 if (mtpt)
205 strncpy(mtpt, mnt->mnt_dir, mtlen);
206 /*
207 * Check to see if we're referring to the root filesystem.
208 * If so, do a manual check to see if we can open /etc/mtab
209 * read/write, since if the root is mounted read/only, the
210 * contents of /etc/mtab may not be accurate.
211 */
212 if (!strcmp(mnt->mnt_dir, "/")) {
213 is_root:
214 #define TEST_FILE "/.ismount-test-file"
215 *mount_flags |= EXT2_MF_ISROOT;
216 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
217 if (fd < 0) {
218 if (errno == EROFS)
219 *mount_flags |= EXT2_MF_READONLY;
220 } else
221 close(fd);
222 (void) unlink(TEST_FILE);
223 }
224 retval = 0;
225 errout:
226 endmntent (f);
227 return retval;
228 }
229
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)230 static errcode_t check_mntent(const char *file, int *mount_flags,
231 char *mtpt, int mtlen)
232 {
233 errcode_t retval;
234
235 #ifdef DEBUG
236 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
237 mtpt, mtlen);
238 if (retval == 0)
239 return 0;
240 #endif /* DEBUG */
241 #ifdef __linux__
242 retval = check_mntent_file("/proc/mounts", file, mount_flags,
243 mtpt, mtlen);
244 if (retval == 0 && (*mount_flags != 0))
245 return 0;
246 #endif /* __linux__ */
247 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
248 #ifndef MOUNTED
249 #define MOUNTED _PATH_MOUNTED
250 #endif /* MOUNTED */
251 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
252 return retval;
253 #else
254 *mount_flags = 0;
255 return 0;
256 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
257 }
258
259 #else
260 #if defined(HAVE_GETMNTINFO)
261
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)262 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
263 char *mtpt, int mtlen)
264 {
265 struct statfs *mp;
266 int len, n;
267 const char *s1;
268 char *s2;
269
270 n = getmntinfo(&mp, MNT_NOWAIT);
271 if (n == 0)
272 return errno;
273
274 len = sizeof(_PATH_DEV) - 1;
275 s1 = file;
276 if (strncmp(_PATH_DEV, s1, len) == 0)
277 s1 += len;
278
279 *mount_flags = 0;
280 while (--n >= 0) {
281 s2 = mp->f_mntfromname;
282 if (strncmp(_PATH_DEV, s2, len) == 0) {
283 s2 += len - 1;
284 *s2 = 'r';
285 }
286 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
287 *mount_flags = EXT2_MF_MOUNTED;
288 break;
289 }
290 ++mp;
291 }
292 if (mtpt)
293 strncpy(mtpt, mp->f_mntonname, mtlen);
294 return 0;
295 }
296 #endif /* HAVE_GETMNTINFO */
297 #endif /* HAVE_SETMNTENT */
298
299 /*
300 * Check to see if we're dealing with the swap device.
301 */
is_swap_device(const char * file)302 static int is_swap_device(const char *file)
303 {
304 FILE *f;
305 char buf[1024], *cp;
306 dev_t file_dev;
307 struct stat st_buf;
308 int ret = 0;
309
310 file_dev = 0;
311 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
312 if ((stat(file, &st_buf) == 0) &&
313 S_ISBLK(st_buf.st_mode))
314 file_dev = st_buf.st_rdev;
315 #endif /* __GNU__ */
316
317 if (!(f = fopen("/proc/swaps", "r")))
318 return 0;
319 /* Skip the first line */
320 if (!fgets(buf, sizeof(buf), f))
321 goto leave;
322 if (*buf && strncmp(buf, "Filename\t", 9))
323 /* Linux <=2.6.19 contained a bug in the /proc/swaps
324 * code where the header would not be displayed
325 */
326 goto valid_first_line;
327
328 while (fgets(buf, sizeof(buf), f)) {
329 valid_first_line:
330 if ((cp = strchr(buf, ' ')) != NULL)
331 *cp = 0;
332 if ((cp = strchr(buf, '\t')) != NULL)
333 *cp = 0;
334 if (strcmp(buf, file) == 0) {
335 ret++;
336 break;
337 }
338 #ifndef __GNU__
339 if (file_dev && (stat(buf, &st_buf) == 0) &&
340 S_ISBLK(st_buf.st_mode) &&
341 file_dev == st_buf.st_rdev) {
342 ret++;
343 break;
344 }
345 #endif /* __GNU__ */
346 }
347
348 leave:
349 fclose(f);
350 return ret;
351 }
352
353
354 /*
355 * ext2fs_check_mount_point() fills determines if the device is
356 * mounted or otherwise busy, and fills in mount_flags with one or
357 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
358 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
359 * non-NULL, the directory where the device is mounted is copied to
360 * where mtpt is pointing, up to mtlen characters.
361 */
362 #ifdef __TURBOC__
363 #pragma argsused
364 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)365 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
366 char *mtpt, int mtlen)
367 {
368 errcode_t retval = 0;
369
370 if (getenv("EXT2FS_PRETEND_RO_MOUNT")) {
371 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY;
372 if (getenv("EXT2FS_PRETEND_ROOTFS"))
373 *mount_flags = EXT2_MF_ISROOT;
374 return 0;
375 }
376 if (getenv("EXT2FS_PRETEND_RW_MOUNT")) {
377 *mount_flags = EXT2_MF_MOUNTED;
378 if (getenv("EXT2FS_PRETEND_ROOTFS"))
379 *mount_flags = EXT2_MF_ISROOT;
380 return 0;
381 }
382
383 if (is_swap_device(device)) {
384 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
385 strncpy(mtpt, "<swap>", mtlen);
386 } else {
387 #ifdef HAVE_SETMNTENT
388 retval = check_mntent(device, mount_flags, mtpt, mtlen);
389 #else
390 #ifdef HAVE_GETMNTINFO
391 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
392 #else
393 #ifdef __GNUC__
394 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
395 #endif
396 *mount_flags = 0;
397 #endif /* HAVE_GETMNTINFO */
398 #endif /* HAVE_SETMNTENT */
399 }
400 if (retval)
401 return retval;
402
403 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
404 {
405 struct stat st_buf;
406
407 if (stat(device, &st_buf) == 0 && S_ISBLK(st_buf.st_mode)) {
408 int fd = open(device, O_RDONLY | O_EXCL);
409
410 if (fd >= 0)
411 close(fd);
412 else if (errno == EBUSY)
413 *mount_flags |= EXT2_MF_BUSY;
414 }
415 }
416 #endif
417
418 return 0;
419 }
420
421 /*
422 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
423 * EXT2_MF_READONLY, and EXT2_MF_ROOT
424 *
425 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)426 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
427 {
428 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
429 }
430
431 #ifdef DEBUG
main(int argc,char ** argv)432 int main(int argc, char **argv)
433 {
434 int retval, mount_flags;
435 char mntpt[80];
436
437 if (argc < 2) {
438 fprintf(stderr, "Usage: %s device\n", argv[0]);
439 exit(1);
440 }
441
442 add_error_table(&et_ext2_error_table);
443 mntpt[0] = 0;
444 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
445 mntpt, sizeof(mntpt));
446 if (retval) {
447 com_err(argv[0], retval,
448 "while calling ext2fs_check_if_mounted");
449 exit(1);
450 }
451 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
452 if (mount_flags & EXT2_MF_BUSY)
453 printf("\t%s is apparently in use.\n", argv[1]);
454 if (mount_flags & EXT2_MF_MOUNTED)
455 printf("\t%s is mounted.\n", argv[1]);
456 if (mount_flags & EXT2_MF_SWAP)
457 printf("\t%s is a swap device.\n", argv[1]);
458 if (mount_flags & EXT2_MF_READONLY)
459 printf("\t%s is read-only.\n", argv[1]);
460 if (mount_flags & EXT2_MF_ISROOT)
461 printf("\t%s is the root filesystem.\n", argv[1]);
462 if (mntpt[0])
463 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
464 exit(0);
465 }
466 #endif /* DEBUG */
467