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_LINUX_LOOP_H 24 #include <linux/loop.h> 25 #include <sys/ioctl.h> 26 #ifdef HAVE_LINUX_MAJOR_H 27 #include <linux/major.h> 28 #endif /* HAVE_LINUX_MAJOR_H */ 29 #endif /* HAVE_LINUX_LOOP_H */ 30 #ifdef HAVE_MNTENT_H 31 #include <mntent.h> 32 #endif 33 #ifdef HAVE_GETMNTINFO 34 #include <paths.h> 35 #include <sys/param.h> 36 #include <sys/mount.h> 37 #endif /* HAVE_GETMNTINFO */ 38 #include <string.h> 39 #include <sys/stat.h> 40 41 #include "ext2_fs.h" 42 #include "ext2fs.h" 43 44 /* 45 * Check to see if a regular file is mounted. 46 * If /etc/mtab/ is a symlink of /proc/mounts, you will need the following check 47 * because the name in /proc/mounts is a loopback device not a regular file. 48 */ 49 static int check_loop_mounted(const char *mnt_fsname, dev_t mnt_rdev, 50 dev_t file_dev, ino_t file_ino) 51 { 52 #if defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) 53 struct loop_info64 loopinfo; 54 int loop_fd, ret; 55 56 if (major(mnt_rdev) == LOOP_MAJOR) { 57 loop_fd = open(mnt_fsname, O_RDONLY); 58 if (loop_fd < 0) 59 return -1; 60 61 ret = ioctl(loop_fd, LOOP_GET_STATUS64, &loopinfo); 62 close(loop_fd); 63 if (ret < 0) 64 return -1; 65 66 if (file_dev == loopinfo.lo_device && 67 file_ino == loopinfo.lo_inode) 68 return 1; 69 } 70 #endif /* defined(HAVE_LINUX_LOOP_H) && defined(HAVE_LINUX_MAJOR_H) */ 71 return 0; 72 } 73 74 #ifdef HAVE_SETMNTENT 75 /* 76 * Helper function which checks a file in /etc/mtab format to see if a 77 * filesystem is mounted. Returns an error if the file doesn't exist 78 * or can't be opened. 79 */ 80 static errcode_t check_mntent_file(const char *mtab_file, const char *file, 81 int *mount_flags, char *mtpt, int mtlen) 82 { 83 struct mntent *mnt; 84 struct stat st_buf; 85 errcode_t retval = 0; 86 dev_t file_dev=0, file_rdev=0; 87 ino_t file_ino=0; 88 FILE *f; 89 int fd; 90 91 *mount_flags = 0; 92 if ((f = setmntent (mtab_file, "r")) == NULL) { 93 if (errno == ENOENT) { 94 if (getenv("EXT2FS_NO_MTAB_OK")) 95 return 0; 96 else 97 return EXT2_ET_NO_MTAB_FILE; 98 } 99 return errno; 100 } 101 if (stat(file, &st_buf) == 0) { 102 if (S_ISBLK(st_buf.st_mode)) { 103 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 104 file_rdev = st_buf.st_rdev; 105 #endif /* __GNU__ */ 106 } else { 107 file_dev = st_buf.st_dev; 108 file_ino = st_buf.st_ino; 109 } 110 } 111 while ((mnt = getmntent (f)) != NULL) { 112 if (mnt->mnt_fsname[0] != '/') 113 continue; 114 if (strcmp(file, mnt->mnt_fsname) == 0) 115 break; 116 if (stat(mnt->mnt_fsname, &st_buf) == 0) { 117 if (S_ISBLK(st_buf.st_mode)) { 118 #ifndef __GNU__ 119 if (file_rdev && (file_rdev == st_buf.st_rdev)) 120 break; 121 if (check_loop_mounted(mnt->mnt_fsname, 122 st_buf.st_rdev, file_dev, 123 file_ino) == 1) 124 break; 125 #endif /* __GNU__ */ 126 } else { 127 if (file_dev && ((file_dev == st_buf.st_dev) && 128 (file_ino == st_buf.st_ino))) 129 break; 130 } 131 } 132 } 133 134 if (mnt == 0) { 135 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 136 /* 137 * Do an extra check to see if this is the root device. We 138 * can't trust /etc/mtab, and /proc/mounts will only list 139 * /dev/root for the root filesystem. Argh. Instead we 140 * check if the given device has the same major/minor number 141 * as the device that the root directory is on. 142 */ 143 if (file_rdev && stat("/", &st_buf) == 0) { 144 if (st_buf.st_dev == file_rdev) { 145 *mount_flags = EXT2_MF_MOUNTED; 146 if (mtpt) 147 strncpy(mtpt, "/", mtlen); 148 goto is_root; 149 } 150 } 151 #endif /* __GNU__ */ 152 goto errout; 153 } 154 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */ 155 /* Validate the entry in case /etc/mtab is out of date */ 156 /* 157 * We need to be paranoid, because some broken distributions 158 * (read: Slackware) don't initialize /etc/mtab before checking 159 * all of the non-root filesystems on the disk. 160 */ 161 if (stat(mnt->mnt_dir, &st_buf) < 0) { 162 retval = errno; 163 if (retval == ENOENT) { 164 #ifdef DEBUG 165 printf("Bogus entry in %s! (%s does not exist)\n", 166 mtab_file, mnt->mnt_dir); 167 #endif /* DEBUG */ 168 retval = 0; 169 } 170 goto errout; 171 } 172 if (file_rdev && (st_buf.st_dev != file_rdev)) { 173 #ifdef DEBUG 174 printf("Bogus entry in %s! (%s not mounted on %s)\n", 175 mtab_file, file, mnt->mnt_dir); 176 #endif /* DEBUG */ 177 goto errout; 178 } 179 #endif /* __GNU__ */ 180 *mount_flags = EXT2_MF_MOUNTED; 181 182 #ifdef MNTOPT_RO 183 /* Check to see if the ro option is set */ 184 if (hasmntopt(mnt, MNTOPT_RO)) 185 *mount_flags |= EXT2_MF_READONLY; 186 #endif 187 188 if (mtpt) 189 strncpy(mtpt, mnt->mnt_dir, mtlen); 190 /* 191 * Check to see if we're referring to the root filesystem. 192 * If so, do a manual check to see if we can open /etc/mtab 193 * read/write, since if the root is mounted read/only, the 194 * contents of /etc/mtab may not be accurate. 195 */ 196 if (!strcmp(mnt->mnt_dir, "/")) { 197 is_root: 198 #define TEST_FILE "/.ismount-test-file" 199 *mount_flags |= EXT2_MF_ISROOT; 200 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600); 201 if (fd < 0) { 202 if (errno == EROFS) 203 *mount_flags |= EXT2_MF_READONLY; 204 } else 205 close(fd); 206 (void) unlink(TEST_FILE); 207 } 208 retval = 0; 209 errout: 210 endmntent (f); 211 return retval; 212 } 213 214 static errcode_t check_mntent(const char *file, int *mount_flags, 215 char *mtpt, int mtlen) 216 { 217 errcode_t retval; 218 219 #ifdef DEBUG 220 retval = check_mntent_file("/tmp/mtab", file, mount_flags, 221 mtpt, mtlen); 222 if (retval == 0) 223 return 0; 224 #endif /* DEBUG */ 225 #ifdef __linux__ 226 retval = check_mntent_file("/proc/mounts", file, mount_flags, 227 mtpt, mtlen); 228 if (retval == 0 && (*mount_flags != 0)) 229 return 0; 230 #endif /* __linux__ */ 231 #if defined(MOUNTED) || defined(_PATH_MOUNTED) 232 #ifndef MOUNTED 233 #define MOUNTED _PATH_MOUNTED 234 #endif /* MOUNTED */ 235 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); 236 return retval; 237 #else 238 *mount_flags = 0; 239 return 0; 240 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */ 241 } 242 243 #else 244 #if defined(HAVE_GETMNTINFO) 245 246 static errcode_t check_getmntinfo(const char *file, int *mount_flags, 247 char *mtpt, int mtlen) 248 { 249 struct statfs *mp; 250 int len, n; 251 const char *s1; 252 char *s2; 253 254 n = getmntinfo(&mp, MNT_NOWAIT); 255 if (n == 0) 256 return errno; 257 258 len = sizeof(_PATH_DEV) - 1; 259 s1 = file; 260 if (strncmp(_PATH_DEV, s1, len) == 0) 261 s1 += len; 262 263 *mount_flags = 0; 264 while (--n >= 0) { 265 s2 = mp->f_mntfromname; 266 if (strncmp(_PATH_DEV, s2, len) == 0) { 267 s2 += len - 1; 268 *s2 = 'r'; 269 } 270 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) { 271 *mount_flags = EXT2_MF_MOUNTED; 272 break; 273 } 274 ++mp; 275 } 276 if (mtpt) 277 strncpy(mtpt, mp->f_mntonname, mtlen); 278 return 0; 279 } 280 #endif /* HAVE_GETMNTINFO */ 281 #endif /* HAVE_SETMNTENT */ 282 283 /* 284 * Check to see if we're dealing with the swap device. 285 */ 286 static int is_swap_device(const char *file) 287 { 288 FILE *f; 289 char buf[1024], *cp; 290 dev_t file_dev; 291 struct stat st_buf; 292 int ret = 0; 293 294 file_dev = 0; 295 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 296 if ((stat(file, &st_buf) == 0) && 297 S_ISBLK(st_buf.st_mode)) 298 file_dev = st_buf.st_rdev; 299 #endif /* __GNU__ */ 300 301 if (!(f = fopen("/proc/swaps", "r"))) 302 return 0; 303 /* Skip the first line */ 304 if (!fgets(buf, sizeof(buf), f)) 305 goto leave; 306 if (*buf && strncmp(buf, "Filename\t", 9)) 307 /* Linux <=2.6.19 contained a bug in the /proc/swaps 308 * code where the header would not be displayed 309 */ 310 goto valid_first_line; 311 312 while (fgets(buf, sizeof(buf), f)) { 313 valid_first_line: 314 if ((cp = strchr(buf, ' ')) != NULL) 315 *cp = 0; 316 if ((cp = strchr(buf, '\t')) != NULL) 317 *cp = 0; 318 if (strcmp(buf, file) == 0) { 319 ret++; 320 break; 321 } 322 #ifndef __GNU__ 323 if (file_dev && (stat(buf, &st_buf) == 0) && 324 S_ISBLK(st_buf.st_mode) && 325 file_dev == st_buf.st_rdev) { 326 ret++; 327 break; 328 } 329 #endif /* __GNU__ */ 330 } 331 332 leave: 333 fclose(f); 334 return ret; 335 } 336 337 338 /* 339 * ext2fs_check_mount_point() fills determines if the device is 340 * mounted or otherwise busy, and fills in mount_flags with one or 341 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT, 342 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is 343 * non-NULL, the directory where the device is mounted is copied to 344 * where mtpt is pointing, up to mtlen characters. 345 */ 346 #ifdef __TURBOC__ 347 #pragma argsused 348 #endif 349 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, 350 char *mtpt, int mtlen) 351 { 352 errcode_t retval = 0; 353 354 if (is_swap_device(device)) { 355 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP; 356 strncpy(mtpt, "<swap>", mtlen); 357 } else { 358 #ifdef HAVE_SETMNTENT 359 retval = check_mntent(device, mount_flags, mtpt, mtlen); 360 #else 361 #ifdef HAVE_GETMNTINFO 362 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen); 363 #else 364 #ifdef __GNUC__ 365 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!" 366 #endif 367 *mount_flags = 0; 368 #endif /* HAVE_GETMNTINFO */ 369 #endif /* HAVE_SETMNTENT */ 370 } 371 if (retval) 372 return retval; 373 374 #ifdef __linux__ /* This only works on Linux 2.6+ systems */ 375 { 376 struct stat st_buf; 377 378 if (stat(device, &st_buf) == 0 && S_ISBLK(st_buf.st_mode)) { 379 int fd = open(device, O_RDONLY | O_EXCL); 380 381 if (fd >= 0) 382 close(fd); 383 else if (errno == EBUSY) 384 *mount_flags |= EXT2_MF_BUSY; 385 } 386 } 387 #endif 388 389 return 0; 390 } 391 392 /* 393 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED, 394 * EXT2_MF_READONLY, and EXT2_MF_ROOT 395 * 396 */ 397 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags) 398 { 399 return ext2fs_check_mount_point(file, mount_flags, NULL, 0); 400 } 401 402 #ifdef DEBUG 403 int main(int argc, char **argv) 404 { 405 int retval, mount_flags; 406 char mntpt[80]; 407 408 if (argc < 2) { 409 fprintf(stderr, "Usage: %s device\n", argv[0]); 410 exit(1); 411 } 412 413 add_error_table(&et_ext2_error_table); 414 mntpt[0] = 0; 415 retval = ext2fs_check_mount_point(argv[1], &mount_flags, 416 mntpt, sizeof(mntpt)); 417 if (retval) { 418 com_err(argv[0], retval, 419 "while calling ext2fs_check_if_mounted"); 420 exit(1); 421 } 422 printf("Device %s reports flags %02x\n", argv[1], mount_flags); 423 if (mount_flags & EXT2_MF_BUSY) 424 printf("\t%s is apparently in use.\n", argv[1]); 425 if (mount_flags & EXT2_MF_MOUNTED) 426 printf("\t%s is mounted.\n", argv[1]); 427 if (mount_flags & EXT2_MF_SWAP) 428 printf("\t%s is a swap device.\n", argv[1]); 429 if (mount_flags & EXT2_MF_READONLY) 430 printf("\t%s is read-only.\n", argv[1]); 431 if (mount_flags & EXT2_MF_ISROOT) 432 printf("\t%s is the root filesystem.\n", argv[1]); 433 if (mntpt[0]) 434 printf("\t%s is mounted on %s.\n", argv[1], mntpt); 435 exit(0); 436 } 437 #endif /* DEBUG */ 438
