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 #include <stdio.h>
13 #if HAVE_UNISTD_H
14 #include <unistd.h>
15 #endif
16 #if HAVE_ERRNO_H
17 #include <errno.h>
18 #endif
19 #include <fcntl.h>
20 #ifdef HAVE_LINUX_FD_H
21 #include <linux/fd.h>
22 #endif
23 #ifdef HAVE_MNTENT_H
24 #include <mntent.h>
25 #endif
26 #ifdef HAVE_GETMNTINFO
27 #include <paths.h>
28 #include <sys/param.h>
29 #include <sys/mount.h>
30 #endif /* HAVE_GETMNTINFO */
31 #include <string.h>
32 #include <sys/stat.h>
33
34 #include "ext2_fs.h"
35 #include "ext2fs.h"
36
37 #ifdef HAVE_MNTENT_H
38 /*
39 * Helper function which checks a file in /etc/mtab format to see if a
40 * filesystem is mounted. Returns an error if the file doesn't exist
41 * or can't be opened.
42 */
check_mntent_file(const char * mtab_file,const char * file,int * mount_flags,char * mtpt,int mtlen)43 static errcode_t check_mntent_file(const char *mtab_file, const char *file,
44 int *mount_flags, char *mtpt, int mtlen)
45 {
46 struct mntent *mnt;
47 struct stat st_buf;
48 errcode_t retval = 0;
49 dev_t file_dev=0, file_rdev=0;
50 ino_t file_ino=0;
51 FILE *f;
52 int fd;
53
54 *mount_flags = 0;
55 if ((f = setmntent (mtab_file, "r")) == NULL)
56 return (errno == ENOENT ? EXT2_NO_MTAB_FILE : errno);
57 if (stat(file, &st_buf) == 0) {
58 if (S_ISBLK(st_buf.st_mode)) {
59 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
60 file_rdev = st_buf.st_rdev;
61 #endif /* __GNU__ */
62 } else {
63 file_dev = st_buf.st_dev;
64 file_ino = st_buf.st_ino;
65 }
66 }
67 while ((mnt = getmntent (f)) != NULL) {
68 if (mnt->mnt_fsname[0] != '/')
69 continue;
70 if (strcmp(file, mnt->mnt_fsname) == 0)
71 break;
72 if (stat(mnt->mnt_fsname, &st_buf) == 0) {
73 if (S_ISBLK(st_buf.st_mode)) {
74 #ifndef __GNU__
75 if (file_rdev && (file_rdev == st_buf.st_rdev))
76 break;
77 #endif /* __GNU__ */
78 } else {
79 if (file_dev && ((file_dev == st_buf.st_dev) &&
80 (file_ino == st_buf.st_ino)))
81 break;
82 }
83 }
84 }
85
86 if (mnt == 0) {
87 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
88 /*
89 * Do an extra check to see if this is the root device. We
90 * can't trust /etc/mtab, and /proc/mounts will only list
91 * /dev/root for the root filesystem. Argh. Instead we
92 * check if the given device has the same major/minor number
93 * as the device that the root directory is on.
94 */
95 if (file_rdev && stat("/", &st_buf) == 0) {
96 if (st_buf.st_dev == file_rdev) {
97 *mount_flags = EXT2_MF_MOUNTED;
98 if (mtpt)
99 strncpy(mtpt, "/", mtlen);
100 goto is_root;
101 }
102 }
103 #endif /* __GNU__ */
104 goto errout;
105 }
106 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */
107 /* Validate the entry in case /etc/mtab is out of date */
108 /*
109 * We need to be paranoid, because some broken distributions
110 * (read: Slackware) don't initialize /etc/mtab before checking
111 * all of the non-root filesystems on the disk.
112 */
113 if (stat(mnt->mnt_dir, &st_buf) < 0) {
114 retval = errno;
115 if (retval == ENOENT) {
116 #ifdef DEBUG
117 printf("Bogus entry in %s! (%s does not exist)\n",
118 mtab_file, mnt->mnt_dir);
119 #endif /* DEBUG */
120 retval = 0;
121 }
122 goto errout;
123 }
124 if (file_rdev && (st_buf.st_dev != file_rdev)) {
125 #ifdef DEBUG
126 printf("Bogus entry in %s! (%s not mounted on %s)\n",
127 mtab_file, file, mnt->mnt_dir);
128 #endif /* DEBUG */
129 goto errout;
130 }
131 #endif /* __GNU__ */
132 *mount_flags = EXT2_MF_MOUNTED;
133
134 #ifdef MNTOPT_RO
135 /* Check to see if the ro option is set */
136 if (hasmntopt(mnt, MNTOPT_RO))
137 *mount_flags |= EXT2_MF_READONLY;
138 #endif
139
140 if (mtpt)
141 strncpy(mtpt, mnt->mnt_dir, mtlen);
142 /*
143 * Check to see if we're referring to the root filesystem.
144 * If so, do a manual check to see if we can open /etc/mtab
145 * read/write, since if the root is mounted read/only, the
146 * contents of /etc/mtab may not be accurate.
147 */
148 if (!strcmp(mnt->mnt_dir, "/")) {
149 is_root:
150 #define TEST_FILE "/.ismount-test-file"
151 *mount_flags |= EXT2_MF_ISROOT;
152 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600);
153 if (fd < 0) {
154 if (errno == EROFS)
155 *mount_flags |= EXT2_MF_READONLY;
156 } else
157 close(fd);
158 (void) unlink(TEST_FILE);
159 }
160 retval = 0;
161 errout:
162 endmntent (f);
163 return retval;
164 }
165
check_mntent(const char * file,int * mount_flags,char * mtpt,int mtlen)166 static errcode_t check_mntent(const char *file, int *mount_flags,
167 char *mtpt, int mtlen)
168 {
169 errcode_t retval;
170
171 #ifdef DEBUG
172 retval = check_mntent_file("/tmp/mtab", file, mount_flags,
173 mtpt, mtlen);
174 if (retval == 0)
175 return 0;
176 #endif /* DEBUG */
177 #ifdef __linux__
178 retval = check_mntent_file("/proc/mounts", file, mount_flags,
179 mtpt, mtlen);
180 if (retval == 0 && (*mount_flags != 0))
181 return 0;
182 #endif /* __linux__ */
183 #if defined(MOUNTED) || defined(_PATH_MOUNTED)
184 #ifndef MOUNTED
185 #define MOUNTED _PATH_MOUNTED
186 #endif /* MOUNTED */
187 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen);
188 return retval;
189 #else
190 *mount_flags = 0;
191 return 0;
192 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */
193 }
194
195 #else
196 #if defined(HAVE_GETMNTINFO)
197
check_getmntinfo(const char * file,int * mount_flags,char * mtpt,int mtlen)198 static errcode_t check_getmntinfo(const char *file, int *mount_flags,
199 char *mtpt, int mtlen)
200 {
201 struct statfs *mp;
202 int len, n;
203 const char *s1;
204 char *s2;
205
206 n = getmntinfo(&mp, MNT_NOWAIT);
207 if (n == 0)
208 return errno;
209
210 len = sizeof(_PATH_DEV) - 1;
211 s1 = file;
212 if (strncmp(_PATH_DEV, s1, len) == 0)
213 s1 += len;
214
215 *mount_flags = 0;
216 while (--n >= 0) {
217 s2 = mp->f_mntfromname;
218 if (strncmp(_PATH_DEV, s2, len) == 0) {
219 s2 += len - 1;
220 *s2 = 'r';
221 }
222 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) {
223 *mount_flags = EXT2_MF_MOUNTED;
224 break;
225 }
226 ++mp;
227 }
228 if (mtpt)
229 strncpy(mtpt, mp->f_mntonname, mtlen);
230 return 0;
231 }
232 #endif /* HAVE_GETMNTINFO */
233 #endif /* HAVE_MNTENT_H */
234
235 /*
236 * Check to see if we're dealing with the swap device.
237 */
is_swap_device(const char * file)238 static int is_swap_device(const char *file)
239 {
240 FILE *f;
241 char buf[1024], *cp;
242 dev_t file_dev;
243 struct stat st_buf;
244 int ret = 0;
245
246 file_dev = 0;
247 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */
248 if ((stat(file, &st_buf) == 0) &&
249 S_ISBLK(st_buf.st_mode))
250 file_dev = st_buf.st_rdev;
251 #endif /* __GNU__ */
252
253 if (!(f = fopen("/proc/swaps", "r")))
254 return 0;
255 /* Skip the first line */
256 if (!fgets(buf, sizeof(buf), f))
257 goto leave;
258 if (*buf && strncmp(buf, "Filename\t", 9))
259 /* Linux <=2.6.19 contained a bug in the /proc/swaps
260 * code where the header would not be displayed
261 */
262 goto valid_first_line;
263
264 while (fgets(buf, sizeof(buf), f)) {
265 valid_first_line:
266 if ((cp = strchr(buf, ' ')) != NULL)
267 *cp = 0;
268 if ((cp = strchr(buf, '\t')) != NULL)
269 *cp = 0;
270 if (strcmp(buf, file) == 0) {
271 ret++;
272 break;
273 }
274 #ifndef __GNU__
275 if (file_dev && (stat(buf, &st_buf) == 0) &&
276 S_ISBLK(st_buf.st_mode) &&
277 file_dev == st_buf.st_rdev) {
278 ret++;
279 break;
280 }
281 #endif /* __GNU__ */
282 }
283
284 leave:
285 fclose(f);
286 return ret;
287 }
288
289
290 /*
291 * ext2fs_check_mount_point() fills determines if the device is
292 * mounted or otherwise busy, and fills in mount_flags with one or
293 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT,
294 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is
295 * non-NULL, the directory where the device is mounted is copied to
296 * where mtpt is pointing, up to mtlen characters.
297 */
298 #ifdef __TURBOC__
299 #pragma argsused
300 #endif
ext2fs_check_mount_point(const char * device,int * mount_flags,char * mtpt,int mtlen)301 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
302 char *mtpt, int mtlen)
303 {
304 struct stat st_buf;
305 errcode_t retval = 0;
306 int fd;
307
308 if (is_swap_device(device)) {
309 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
310 strncpy(mtpt, "<swap>", mtlen);
311 } else {
312 #ifdef HAVE_MNTENT_H
313 retval = check_mntent(device, mount_flags, mtpt, mtlen);
314 #else
315 #ifdef HAVE_GETMNTINFO
316 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen);
317 #else
318 #ifdef __GNUC__
319 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
320 #endif
321 *mount_flags = 0;
322 #endif /* HAVE_GETMNTINFO */
323 #endif /* HAVE_MNTENT_H */
324 }
325 if (retval)
326 return retval;
327
328 #ifdef __linux__ /* This only works on Linux 2.6+ systems */
329 if ((stat(device, &st_buf) != 0) ||
330 !S_ISBLK(st_buf.st_mode))
331 return 0;
332 fd = open(device, O_RDONLY | O_EXCL);
333 if (fd < 0) {
334 if (errno == EBUSY)
335 *mount_flags |= EXT2_MF_BUSY;
336 } else
337 close(fd);
338 #endif
339
340 return 0;
341 }
342
343 /*
344 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
345 * EXT2_MF_READONLY, and EXT2_MF_ROOT
346 *
347 */
ext2fs_check_if_mounted(const char * file,int * mount_flags)348 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
349 {
350 return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
351 }
352
353 #ifdef DEBUG
main(int argc,char ** argv)354 int main(int argc, char **argv)
355 {
356 int retval, mount_flags;
357 char mntpt[80];
358
359 if (argc < 2) {
360 fprintf(stderr, "Usage: %s device\n", argv[0]);
361 exit(1);
362 }
363
364 add_error_table(&et_ext2_error_table);
365 mntpt[0] = 0;
366 retval = ext2fs_check_mount_point(argv[1], &mount_flags,
367 mntpt, sizeof(mntpt));
368 if (retval) {
369 com_err(argv[0], retval,
370 "while calling ext2fs_check_if_mounted");
371 exit(1);
372 }
373 printf("Device %s reports flags %02x\n", argv[1], mount_flags);
374 if (mount_flags & EXT2_MF_BUSY)
375 printf("\t%s is apparently in use.\n", argv[1]);
376 if (mount_flags & EXT2_MF_MOUNTED)
377 printf("\t%s is mounted.\n", argv[1]);
378 if (mount_flags & EXT2_MF_SWAP)
379 printf("\t%s is a swap device.\n", argv[1]);
380 if (mount_flags & EXT2_MF_READONLY)
381 printf("\t%s is read-only.\n", argv[1]);
382 if (mount_flags & EXT2_MF_ISROOT)
383 printf("\t%s is the root filesystem.\n", argv[1]);
384 if (mntpt[0])
385 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
386 exit(0);
387 }
388 #endif /* DEBUG */
389