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 if (stat(mnt->mnt_dir, &st_buf) != 0)
133 continue;
134 if (file_rdev && (file_rdev != st_buf.st_dev)) {
135 #ifdef DEBUG
136 printf("Bogus entry in %s! "
137 "(%s is not mounted on %s)\n",
138 mtab_file, file, mnt->mnt_dir);
139 #endif /* DEBUG */
140 continue;
141 }
142 break;
143 }
144 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
145 if (ext2fsP_is_disk_device(st_buf.st_mode)) {
146 #ifndef __GNU__
147 if (file_rdev && (file_rdev == st_buf.st_rdev))
148 break;
149 if (check_loop_mounted(mnt->mnt_fsname,
150 st_buf.st_rdev, file_dev,
151 file_ino) == 1)
152 break;
153 #endif /* __GNU__ */
154 } else {
155 if (file_dev && ((file_dev == st_buf.st_dev) &&
156 (file_ino == st_buf.st_ino)))
157 break;
158 }
159 }
160 }
161
162 if (mnt == 0) {
163 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
164 /*
165 * Do an extra check to see if this is the root device. We
166 * can't trust /etc/mtab, and /proc/mounts will only list
167 * /dev/root for the root filesystem. Argh. Instead we
168 * check if the given device has the same major/minor number
169 * as the device that the root directory is on.
170 */
171 if (file_rdev && stat("/", &st_buf) == 0) {
172 if (st_buf.st_dev == file_rdev) {
173 *mount_flags = EXT2_MF_MOUNTED;
174 if (mtpt)
175 strncpy(mtpt, "/", mtlen);
176 goto is_root;
177 }
178 }
179 #endif /* __GNU__ */
180 goto errout;
181 }
182 *mount_flags = EXT2_MF_MOUNTED;
183
184 #ifdef MNTOPT_RO
185 /* Check to see if the ro option is set */
186 if (hasmntopt(mnt, MNTOPT_RO))
187 *mount_flags |= EXT2_MF_READONLY;
188 #endif
189
190 if (mtpt)
191 strncpy(mtpt, mnt->mnt_dir, mtlen);
192 /*
193 * Check to see if we're referring to the root filesystem.
194 * If so, do a manual check to see if we can open /etc/mtab
195 * read/write, since if the root is mounted read/only, the
196 * contents of /etc/mtab may not be accurate.
197 */
198 if (!strcmp(mnt->mnt_dir, "/")) {
199 is_root:
200 #define TEST_FILE "/.ismount-test-file"
201 *mount_flags |= EXT2_MF_ISROOT;
202 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
203 if (fd < 0) {
204 if (errno == EROFS)
205 *mount_flags |= EXT2_MF_READONLY;
206 } else
207 close(fd);
208 (void) unlink(TEST_FILE);
209 }
210 retval = 0;
211 errout:
212 endmntent (f);
213 return retval;
214 }
215
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)216 static errcode_t check_mntent(const char *file, int *mount_flags,
217 char *mtpt, int mtlen)
218 {
219 errcode_t retval;
220
221 #ifdef DEBUG
222 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
223 mtpt, mtlen);
224 if (retval == 0)
225 return 0;
226 #endif /* DEBUG */
227 #ifdef __linux__
228 retval = check_mntent_file("/proc/mounts", file, mount_flags,
229 mtpt, mtlen);
230 if (retval == 0)
231 return 0;
232 #endif /* __linux__ */
233 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
234 #ifndef MOUNTED
235 #define MOUNTED _PATH_MOUNTED
236 #endif /* MOUNTED */
237 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
238 return retval;
239 #else
240 *mount_flags = 0;
241 return 0;
242 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
243 }
244
245 #else
246 #if defined(HAVE_GETMNTINFO)
247
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)248 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
249 char *mtpt, int mtlen)
250 {
251 struct statfs *mp;
252 int len, n;
253 const char *s1;
254 char *s2;
255
256 n = getmntinfo(&mp, MNT_NOWAIT);
257 if (n == 0)
258 return errno;
259
260 len = sizeof(_PATH_DEV) - 1;
261 s1 = file;
262 if (strncmp(_PATH_DEV, s1, len) == 0)
263 s1 += len;
264
265 *mount_flags = 0;
266 while (--n >= 0) {
267 s2 = mp->f_mntfromname;
268 if (strncmp(_PATH_DEV, s2, len) == 0) {
269 s2 += len - 1;
270 *s2 = 'r';
271 }
272 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
273 *mount_flags = EXT2_MF_MOUNTED;
274 break;
275 }
276 ++mp;
277 }
278 if (mtpt)
279 strncpy(mtpt, mp->f_mntonname, mtlen);
280 return 0;
281 }
282 #endif /* HAVE_GETMNTINFO */
283 #endif /* HAVE_SETMNTENT */
284
285 /*
286 * Check to see if we're dealing with the swap device.
287 */
is_swap_device(const char * file)288 static int is_swap_device(const char *file)
289 {
290 FILE *f;
291 char buf[1024], *cp;
292 dev_t file_dev;
293 struct stat st_buf;
294 int ret = 0;
295
296 file_dev = 0;
297 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
298 if ((stat(file, &st_buf) == 0) &&
299 ext2fsP_is_disk_device(st_buf.st_mode))
300 file_dev = st_buf.st_rdev;
301 #endif /* __GNU__ */
302
303 if (!(f = fopen("/proc/swaps", "r")))
304 return 0;
305 /* Skip the first line */
306 if (!fgets(buf, sizeof(buf), f))
307 goto leave;
308 if (*buf && strncmp(buf, "Filename\t", 9))
309 /* Linux <=2.6.19 contained a bug in the /proc/swaps
310 * code where the header would not be displayed
311 */
312 goto valid_first_line;
313
314 while (fgets(buf, sizeof(buf), f)) {
315 valid_first_line:
316 if ((cp = strchr(buf, ' ')) != NULL)
317 *cp = 0;
318 if ((cp = strchr(buf, '\t')) != NULL)
319 *cp = 0;
320 if (strcmp(buf, file) == 0) {
321 ret++;
322 break;
323 }
324 #ifndef __GNU__
325 if (file_dev && (stat(buf, &st_buf) == 0) &&
326 ext2fsP_is_disk_device(st_buf.st_mode) &&
327 file_dev == st_buf.st_rdev) {
328 ret++;
329 break;
330 }
331 #endif /* __GNU__ */
332 }
333
334 leave:
335 fclose(f);
336 return ret;
337 }
338
339
340 /*
341 * ext2fs_check_mount_point() fills determines if the device is
342 * mounted or otherwise busy, and fills in mount_flags with one or
343 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
344 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
345 * non-NULL, the directory where the device is mounted is copied to
346 * where mtpt is pointing, up to mtlen characters.
347 */
348 #ifdef __TURBOC__
349 #pragma argsused
350 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)351 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
352 char *mtpt, int mtlen)
353 {
354 errcode_t retval = 0;
355 int busy = 0;
356
357 if (getenv("EXT2FS_PRETEND_RO_MOUNT")) {
358 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY;
359 if (getenv("EXT2FS_PRETEND_ROOTFS"))
360 *mount_flags = EXT2_MF_ISROOT;
361 return 0;
362 }
363 if (getenv("EXT2FS_PRETEND_RW_MOUNT")) {
364 *mount_flags = EXT2_MF_MOUNTED;
365 if (getenv("EXT2FS_PRETEND_ROOTFS"))
366 *mount_flags = EXT2_MF_ISROOT;
367 return 0;
368 }
369
370 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
371 {
372 struct stat st_buf;
373
374 if (stat(device, &st_buf) == 0 &&
375 ext2fsP_is_disk_device(st_buf.st_mode)) {
376 int fd = open(device, O_RDONLY | O_EXCL);
377
378 if (fd >= 0) {
379 /*
380 * The device is not busy so it's
381 * definitelly not mounted. No need to
382 * to perform any more checks.
383 */
384 close(fd);
385 *mount_flags = 0;
386 return 0;
387 } else if (errno == EBUSY) {
388 busy = 1;
389 }
390 }
391 }
392 #endif
393
394 if (is_swap_device(device)) {
395 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
396 if (mtpt)
397 strncpy(mtpt, "<swap>", mtlen);
398 } else {
399 #ifdef HAVE_SETMNTENT
400 retval = check_mntent(device, mount_flags, mtpt, mtlen);
401 #else
402 #ifdef HAVE_GETMNTINFO
403 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
404 #else
405 #ifdef __GNUC__
406 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
407 #endif
408 *mount_flags = 0;
409 #endif /* HAVE_GETMNTINFO */
410 #endif /* HAVE_SETMNTENT */
411 }
412 if (retval)
413 return retval;
414
415 if (busy)
416 *mount_flags |= EXT2_MF_BUSY;
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