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