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