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, dir_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 &&
148 (file_rdev == st_buf.st_rdev)) {
149 if (stat(mnt->mnt_dir,
150 &dir_st_buf) != 0)
151 continue;
152 if (file_rdev == dir_st_buf.st_dev)
153 break;
154 }
155 if (check_loop_mounted(mnt->mnt_fsname,
156 st_buf.st_rdev, file_dev,
157 file_ino) == 1)
158 break;
159 #endif /* __GNU__ */
160 } else {
161 if (file_dev && ((file_dev == st_buf.st_dev) &&
162 (file_ino == st_buf.st_ino)))
163 break;
164 }
165 }
166 }
167
168 if (mnt == 0) {
169 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
170 /*
171 * Do an extra check to see if this is the root device. We
172 * can't trust /etc/mtab, and /proc/mounts will only list
173 * /dev/root for the root filesystem. Argh. Instead we
174 * check if the given device has the same major/minor number
175 * as the device that the root directory is on.
176 */
177 if (file_rdev && stat("/", &st_buf) == 0) {
178 if (st_buf.st_dev == file_rdev) {
179 *mount_flags = EXT2_MF_MOUNTED;
180 if (mtpt)
181 strncpy(mtpt, "/", mtlen);
182 goto is_root;
183 }
184 }
185 #endif /* __GNU__ */
186 goto errout;
187 }
188 *mount_flags = EXT2_MF_MOUNTED;
189
190 #ifdef MNTOPT_RO
191 /* Check to see if the ro option is set */
192 if (hasmntopt(mnt, MNTOPT_RO))
193 *mount_flags |= EXT2_MF_READONLY;
194 #endif
195
196 if (mtpt)
197 strncpy(mtpt, mnt->mnt_dir, mtlen);
198 /*
199 * Check to see if we're referring to the root filesystem.
200 * If so, do a manual check to see if we can open /etc/mtab
201 * read/write, since if the root is mounted read/only, the
202 * contents of /etc/mtab may not be accurate.
203 */
204 if (!strcmp(mnt->mnt_dir, "/")) {
205 is_root:
206 #define TEST_FILE "/.ismount-test-file"
207 *mount_flags |= EXT2_MF_ISROOT;
208 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
209 if (fd < 0) {
210 if (errno == EROFS)
211 *mount_flags |= EXT2_MF_READONLY;
212 } else
213 close(fd);
214 (void) unlink(TEST_FILE);
215 }
216 retval = 0;
217 errout:
218 endmntent (f);
219 return retval;
220 }
221
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)222 static errcode_t check_mntent(const char *file, int *mount_flags,
223 char *mtpt, int mtlen)
224 {
225 errcode_t retval;
226
227 #ifdef DEBUG
228 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
229 mtpt, mtlen);
230 if (retval == 0)
231 return 0;
232 #endif /* DEBUG */
233 #ifdef __linux__
234 retval = check_mntent_file("/proc/mounts", file, mount_flags,
235 mtpt, mtlen);
236 if (retval == 0)
237 return 0;
238 #endif /* __linux__ */
239 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
240 #ifndef MOUNTED
241 #define MOUNTED _PATH_MOUNTED
242 #endif /* MOUNTED */
243 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
244 return retval;
245 #else
246 *mount_flags = 0;
247 return 0;
248 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
249 }
250
251 #else
252 #if defined(HAVE_GETMNTINFO)
253
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)254 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
255 char *mtpt, int mtlen)
256 {
257 struct statfs *mp;
258 int len, n;
259 const char *s1;
260 char *s2;
261
262 n = getmntinfo(&mp, MNT_NOWAIT);
263 if (n == 0)
264 return errno;
265
266 len = sizeof(_PATH_DEV) - 1;
267 s1 = file;
268 if (strncmp(_PATH_DEV, s1, len) == 0)
269 s1 += len;
270
271 *mount_flags = 0;
272 while (--n >= 0) {
273 s2 = mp->f_mntfromname;
274 if (strncmp(_PATH_DEV, s2, len) == 0) {
275 s2 += len - 1;
276 *s2 = 'r';
277 }
278 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
279 *mount_flags = EXT2_MF_MOUNTED;
280 break;
281 }
282 ++mp;
283 }
284 if (mtpt)
285 strncpy(mtpt, mp->f_mntonname, mtlen);
286 return 0;
287 }
288 #endif /* HAVE_GETMNTINFO */
289 #endif /* HAVE_SETMNTENT */
290
291 /*
292 * Check to see if we're dealing with the swap device.
293 */
is_swap_device(const char * file)294 static int is_swap_device(const char *file)
295 {
296 FILE *f;
297 char buf[1024], *cp;
298 dev_t file_dev;
299 struct stat st_buf;
300 int ret = 0;
301
302 file_dev = 0;
303 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
304 if ((stat(file, &st_buf) == 0) &&
305 ext2fsP_is_disk_device(st_buf.st_mode))
306 file_dev = st_buf.st_rdev;
307 #endif /* __GNU__ */
308
309 if (!(f = fopen("/proc/swaps", "r")))
310 return 0;
311 /* Skip the first line */
312 if (!fgets(buf, sizeof(buf), f))
313 goto leave;
314 if (*buf && strncmp(buf, "Filename\t", 9))
315 /* Linux <=2.6.19 contained a bug in the /proc/swaps
316 * code where the header would not be displayed
317 */
318 goto valid_first_line;
319
320 while (fgets(buf, sizeof(buf), f)) {
321 valid_first_line:
322 if ((cp = strchr(buf, ' ')) != NULL)
323 *cp = 0;
324 if ((cp = strchr(buf, '\t')) != NULL)
325 *cp = 0;
326 if (strcmp(buf, file) == 0) {
327 ret++;
328 break;
329 }
330 #ifndef __GNU__
331 if (file_dev && (stat(buf, &st_buf) == 0) &&
332 ext2fsP_is_disk_device(st_buf.st_mode) &&
333 file_dev == st_buf.st_rdev) {
334 ret++;
335 break;
336 }
337 #endif /* __GNU__ */
338 }
339
340 leave:
341 fclose(f);
342 return ret;
343 }
344
345
346 /*
347 * ext2fs_check_mount_point() fills determines if the device is
348 * mounted or otherwise busy, and fills in mount_flags with one or
349 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
350 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
351 * non-NULL, the directory where the device is mounted is copied to
352 * where mtpt is pointing, up to mtlen characters.
353 */
354 #ifdef __TURBOC__
355 #pragma argsused
356 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)357 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
358 char *mtpt, int mtlen)
359 {
360 errcode_t retval = 0;
361 int busy = 0;
362
363 if (getenv("EXT2FS_PRETEND_RO_MOUNT")) {
364 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_READONLY;
365 if (getenv("EXT2FS_PRETEND_ROOTFS"))
366 *mount_flags = EXT2_MF_ISROOT;
367 return 0;
368 }
369 if (getenv("EXT2FS_PRETEND_RW_MOUNT")) {
370 *mount_flags = EXT2_MF_MOUNTED;
371 if (getenv("EXT2FS_PRETEND_ROOTFS"))
372 *mount_flags = EXT2_MF_ISROOT;
373 return 0;
374 }
375
376 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
377 {
378 struct stat st_buf;
379
380 if (stat(device, &st_buf) == 0 &&
381 ext2fsP_is_disk_device(st_buf.st_mode)) {
382 int fd = open(device, O_RDONLY | O_EXCL);
383
384 if (fd >= 0) {
385 /*
386 * The device is not busy so it's
387 * definitelly not mounted. No need to
388 * to perform any more checks.
389 */
390 close(fd);
391 *mount_flags = 0;
392 return 0;
393 } else if (errno == EBUSY) {
394 busy = 1;
395 }
396 }
397 }
398 #endif
399
400 if (is_swap_device(device)) {
401 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
402 if (mtpt)
403 strncpy(mtpt, "<swap>", mtlen);
404 } else {
405 #ifdef HAVE_SETMNTENT
406 retval = check_mntent(device, mount_flags, mtpt, mtlen);
407 #else
408 #ifdef HAVE_GETMNTINFO
409 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
410 #else
411 #if defined(__GNUC__) && !defined(_WIN32)
412 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
413 #endif
414 *mount_flags = 0;
415 #endif /* HAVE_GETMNTINFO */
416 #endif /* HAVE_SETMNTENT */
417 }
418 if (retval)
419 return retval;
420
421 if (busy)
422 *mount_flags |= EXT2_MF_BUSY;
423
424 return 0;
425 }
426
427 /*
428 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
429 * EXT2_MF_READONLY, and EXT2_MF_ROOT
430 *
431 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)432 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
433 {
434 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
435 }
436
437 #ifdef DEBUG
main(int argc,char ** argv)438 int main(int argc, char **argv)
439 {
440 int retval, mount_flags;
441 char mntpt[80];
442
443 if (argc < 2) {
444 fprintf(stderr, "Usage: %s device\n", argv[0]);
445 exit(1);
446 }
447
448 add_error_table(&et_ext2_error_table);
449 mntpt[0] = 0;
450 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
451 mntpt, sizeof(mntpt));
452 if (retval) {
453 com_err(argv[0], retval,
454 "while calling ext2fs_check_if_mounted");
455 exit(1);
456 }
457 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
458 if (mount_flags & EXT2_MF_BUSY)
459 printf("\t%s is apparently in use.\n", argv[1]);
460 if (mount_flags & EXT2_MF_MOUNTED)
461 printf("\t%s is mounted.\n", argv[1]);
462 if (mount_flags & EXT2_MF_SWAP)
463 printf("\t%s is a swap device.\n", argv[1]);
464 if (mount_flags & EXT2_MF_READONLY)
465 printf("\t%s is read-only.\n", argv[1]);
466 if (mount_flags & EXT2_MF_ISROOT)
467 printf("\t%s is the root filesystem.\n", argv[1]);
468 if (mntpt[0])
469 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
470 exit(0);
471 }
472 #endif /* DEBUG */
473