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 #include "ext2fsP.h"
59
60 #ifdef HAVE_SETMNTENT
61 /*
62 * Check to see if a regular file is mounted.
63 * If /etc/mtab/ is a symlink of /proc/mounts, you will need the following check
64 * because the name in /proc/mounts is a loopback device not a regular file.
65 */
check_loop_mounted(const char * mnt_fsname,dev_t mnt_rdev,dev_t file_dev,ino_t file_ino)66 static int check_loop_mounted(const char *mnt_fsname, dev_t mnt_rdev,
67 dev_t file_dev, ino_t file_ino)
68 {
69 #if defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H)
70 struct loop_info64 loopinfo = {0, };
71 int loop_fd, ret;
72
73 if (major(mnt_rdev) == LOOP_MAJOR) {
74 loop_fd = open(mnt_fsname, O_RDONLY);
75 if (loop_fd < 0)
76 return -1;
77
78 ret = ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo);
79 close(loop_fd);
80 if (ret < 0)
81 return -1;
82
83 if (file_dev == loopinfo.lo_device &&
84 file_ino == loopinfo.lo_inode)
85 return 1;
86 }
87 #endif /* defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) */
88 return 0;
89 }
90
91 /*
92 * Helper function which checks a file in /etc/mtab format to see if a
93 * filesystem is mounted. Returns an error if the file doesn't exist
94 * or can't be opened.
95 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags,char * mtpt,int mtlen)96 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
97 int *mount_flags, char *mtpt, int mtlen)
98 {
99 struct mntent *mnt;
100 struct stat st_buf;
101 errcode_t retval = 0;
102 dev_t file_dev=0, file_rdev=0;
103 ino_t file_ino=0;
104 FILE *f;
105 int fd;
106
107 *mount_flags = 0;
108
109 if ((f = setmntent (mtab_file, "r")) == NULL) {
110 if (errno == ENOENT) {
111 if (getenv("EXT2FS_NO_MTAB_OK"))
112 return 0;
113 else
114 return EXT2_ET_NO_MTAB_FILE;
115 }
116 return errno;
117 }
118 if (stat(file, &st_buf) == 0) {
119 if (ext2fsP_is_disk_device(st_buf.st_mode)) {
120 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
121 file_rdev = st_buf.st_rdev;
122 #endif /* __GNU__ */
123 } else {
124 file_dev = st_buf.st_dev;
125 file_ino = st_buf.st_ino;
126 }
127 }
128 while ((mnt = getmntent (f)) != NULL) {
129 if (mnt->mnt_fsname[0] != '/')
130 continue;
131 if (strcmp(file, mnt->mnt_fsname) == 0)
132 break;
133 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
134 if (ext2fsP_is_disk_device(st_buf.st_mode)) {
135 #ifndef __GNU__
136 if (file_rdev && (file_rdev == st_buf.st_rdev))
137 break;
138 if (check_loop_mounted(mnt->mnt_fsname,
139 st_buf.st_rdev, file_dev,
140 file_ino) == 1)
141 break;
142 #endif /* __GNU__ */
143 } else {
144 if (file_dev && ((file_dev == st_buf.st_dev) &&
145 (file_ino == st_buf.st_ino)))
146 break;
147 }
148 }
149 }
150
151 if (mnt == 0) {
152 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
153 /*
154 * Do an extra check to see if this is the root device. We
155 * can't trust /etc/mtab, and /proc/mounts will only list
156 * /dev/root for the root filesystem. Argh. Instead we
157 * check if the given device has the same major/minor number
158 * as the device that the root directory is on.
159 */
160 if (file_rdev && stat("/", &st_buf) == 0) {
161 if (st_buf.st_dev == file_rdev) {
162 *mount_flags = EXT2_MF_MOUNTED;
163 if (mtpt)
164 strncpy(mtpt, "/", mtlen);
165 goto is_root;
166 }
167 }
168 #endif /* __GNU__ */
169 goto errout;
170 }
171 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
172 /* Validate the entry in case /etc/mtab is out of date */
173 /*
174 * We need to be paranoid, because some broken distributions
175 * (read: Slackware) don't initialize /etc/mtab before checking
176 * all of the non-root filesystems on the disk.
177 */
178 if (stat(mnt->mnt_dir, &st_buf) < 0) {
179 retval = errno;
180 if (retval == ENOENT) {
181 #ifdef DEBUG
182 printf("Bogus entry in %s! (%s does not exist)\n",
183 mtab_file, mnt->mnt_dir);
184 #endif /* DEBUG */
185 retval = 0;
186 }
187 goto errout;
188 }
189 if (file_rdev && (st_buf.st_dev != file_rdev)) {
190 #ifdef DEBUG
191 printf("Bogus entry in %s! (%s not mounted on %s)\n",
192 mtab_file, file, mnt->mnt_dir);
193 #endif /* DEBUG */
194 goto errout;
195 }
196 #endif /* __GNU__ */
197 *mount_flags = EXT2_MF_MOUNTED;
198
199 #ifdef MNTOPT_RO
200 /* Check to see if the ro option is set */
201 if (hasmntopt(mnt, MNTOPT_RO))
202 *mount_flags |= EXT2_MF_READONLY;
203 #endif
204
205 if (mtpt)
206 strncpy(mtpt, mnt->mnt_dir, mtlen);
207 /*
208 * Check to see if we're referring to the root filesystem.
209 * If so, do a manual check to see if we can open /etc/mtab
210 * read/write, since if the root is mounted read/only, the
211 * contents of /etc/mtab may not be accurate.
212 */
213 if (!strcmp(mnt->mnt_dir, "/")) {
214 is_root:
215 #define TEST_FILE "/.ismount-test-file"
216 *mount_flags |= EXT2_MF_ISROOT;
217 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
218 if (fd < 0) {
219 if (errno == EROFS)
220 *mount_flags |= EXT2_MF_READONLY;
221 } else
222 close(fd);
223 (void) unlink(TEST_FILE);
224 }
225 retval = 0;
226 errout:
227 endmntent (f);
228 return retval;
229 }
230
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)231 static errcode_t check_mntent(const char *file, int *mount_flags,
232 char *mtpt, int mtlen)
233 {
234 errcode_t retval;
235
236 #ifdef DEBUG
237 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
238 mtpt, mtlen);
239 if (retval == 0)
240 return 0;
241 #endif /* DEBUG */
242 #ifdef __linux__
243 retval = check_mntent_file("/proc/mounts", file, mount_flags,
244 mtpt, mtlen);
245 if (retval == 0 && (*mount_flags != 0))
246 return 0;
247 #endif /* __linux__ */
248 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
249 #ifndef MOUNTED
250 #define MOUNTED _PATH_MOUNTED
251 #endif /* MOUNTED */
252 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
253 return retval;
254 #else
255 *mount_flags = 0;
256 return 0;
257 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
258 }
259
260 #else
261 #if defined(HAVE_GETMNTINFO)
262
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)263 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
264 char *mtpt, int mtlen)
265 {
266 struct statfs *mp;
267 int len, n;
268 const char *s1;
269 char *s2;
270
271 n = getmntinfo(&mp, MNT_NOWAIT);
272 if (n == 0)
273 return errno;
274
275 len = sizeof(_PATH_DEV) - 1;
276 s1 = file;
277 if (strncmp(_PATH_DEV, s1, len) == 0)
278 s1 += len;
279
280 *mount_flags = 0;
281 while (--n >= 0) {
282 s2 = mp->f_mntfromname;
283 if (strncmp(_PATH_DEV, s2, len) == 0) {
284 s2 += len - 1;
285 *s2 = 'r';
286 }
287 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
288 *mount_flags = EXT2_MF_MOUNTED;
289 break;
290 }
291 ++mp;
292 }
293 if (mtpt)
294 strncpy(mtpt, mp->f_mntonname, mtlen);
295 return 0;
296 }
297 #endif /* HAVE_GETMNTINFO */
298 #endif /* HAVE_SETMNTENT */
299
300 /*
301 * Check to see if we're dealing with the swap device.
302 */
is_swap_device(const char * file)303 static int is_swap_device(const char *file)
304 {
305 FILE *f;
306 char buf[1024], *cp;
307 dev_t file_dev;
308 struct stat st_buf;
309 int ret = 0;
310
311 file_dev = 0;
312 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
313 if ((stat(file, &st_buf) == 0) &&
314 ext2fsP_is_disk_device(st_buf.st_mode))
315 file_dev = st_buf.st_rdev;
316 #endif /* __GNU__ */
317
318 if (!(f = fopen("/proc/swaps", "r")))
319 return 0;
320 /* Skip the first line */
321 if (!fgets(buf, sizeof(buf), f))
322 goto leave;
323 if (*buf && strncmp(buf, "Filename\t", 9))
324 /* Linux <=2.6.19 contained a bug in the /proc/swaps
325 * code where the header would not be displayed
326 */
327 goto valid_first_line;
328
329 while (fgets(buf, sizeof(buf), f)) {
330 valid_first_line:
331 if ((cp = strchr(buf, ' ')) != NULL)
332 *cp = 0;
333 if ((cp = strchr(buf, '\t')) != NULL)
334 *cp = 0;
335 if (strcmp(buf, file) == 0) {
336 ret++;
337 break;
338 }
339 #ifndef __GNU__
340 if (file_dev && (stat(buf, &st_buf) == 0) &&
341 ext2fsP_is_disk_device(st_buf.st_mode) &&
342 file_dev == st_buf.st_rdev) {
343 ret++;
344 break;
345 }
346 #endif /* __GNU__ */
347 }
348
349 leave:
350 fclose(f);
351 return ret;
352 }
353
354
355 /*
356 * ext2fs_check_mount_point() fills determines if the device is
357 * mounted or otherwise busy, and fills in mount_flags with one or
358 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
359 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
360 * non-NULL, the directory where the device is mounted is copied to
361 * where mtpt is pointing, up to mtlen characters.
362 */
363 #ifdef __TURBOC__
364 #pragma argsused
365 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)366 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
367 char *mtpt, int mtlen)
368 {
369 errcode_t retval = 0;
370
371 if (getenv("EXT2FS_PRETEND_RO_MOUNT")) {
372 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY;
373 if (getenv("EXT2FS_PRETEND_ROOTFS"))
374 *mount_flags = EXT2_MF_ISROOT;
375 return 0;
376 }
377 if (getenv("EXT2FS_PRETEND_RW_MOUNT")) {
378 *mount_flags = EXT2_MF_MOUNTED;
379 if (getenv("EXT2FS_PRETEND_ROOTFS"))
380 *mount_flags = EXT2_MF_ISROOT;
381 return 0;
382 }
383
384 if (is_swap_device(device)) {
385 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
386 strncpy(mtpt, "<swap>", mtlen);
387 } else {
388 #ifdef HAVE_SETMNTENT
389 retval = check_mntent(device, mount_flags, mtpt, mtlen);
390 #else
391 #ifdef HAVE_GETMNTINFO
392 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
393 #else
394 #ifdef __GNUC__
395 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
396 #endif
397 *mount_flags = 0;
398 #endif /* HAVE_GETMNTINFO */
399 #endif /* HAVE_SETMNTENT */
400 }
401 if (retval)
402 return retval;
403
404 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
405 {
406 struct stat st_buf;
407
408 if (stat(device, &st_buf) == 0 &&
409 ext2fsP_is_disk_device(st_buf.st_mode)) {
410 int fd = open(device, O_RDONLY | O_EXCL);
411
412 if (fd >= 0)
413 close(fd);
414 else if (errno == EBUSY)
415 *mount_flags |= EXT2_MF_BUSY;
416 }
417 }
418 #endif
419
420 return 0;
421 }
422
423 /*
424 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
425 * EXT2_MF_READONLY, and EXT2_MF_ROOT
426 *
427 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)428 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
429 {
430 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
431 }
432
433 #ifdef DEBUG
main(int argc,char ** argv)434 int main(int argc, char **argv)
435 {
436 int retval, mount_flags;
437 char mntpt[80];
438
439 if (argc < 2) {
440 fprintf(stderr, "Usage: %s device\n", argv[0]);
441 exit(1);
442 }
443
444 add_error_table(&et_ext2_error_table);
445 mntpt[0] = 0;
446 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
447 mntpt, sizeof(mntpt));
448 if (retval) {
449 com_err(argv[0], retval,
450 "while calling ext2fs_check_if_mounted");
451 exit(1);
452 }
453 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
454 if (mount_flags & EXT2_MF_BUSY)
455 printf("\t%s is apparently in use.\n", argv[1]);
456 if (mount_flags & EXT2_MF_MOUNTED)
457 printf("\t%s is mounted.\n", argv[1]);
458 if (mount_flags & EXT2_MF_SWAP)
459 printf("\t%s is a swap device.\n", argv[1]);
460 if (mount_flags & EXT2_MF_READONLY)
461 printf("\t%s is read-only.\n", argv[1]);
462 if (mount_flags & EXT2_MF_ISROOT)
463 printf("\t%s is the root filesystem.\n", argv[1]);
464 if (mntpt[0])
465 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
466 exit(0);
467 }
468 #endif /* DEBUG */
469