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 Public 8 * License. 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 */ 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; 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 (strcmp(file, mnt->mnt_fsname) == 0) 69 break; 70 if (stat(mnt->mnt_fsname, &st_buf) == 0) { 71 if (S_ISBLK(st_buf.st_mode)) { 72 #ifndef __GNU__ 73 if (file_rdev && (file_rdev == st_buf.st_rdev)) 74 break; 75 #endif /* __GNU__ */ 76 } else { 77 if (file_dev && ((file_dev == st_buf.st_dev) && 78 (file_ino == st_buf.st_ino))) 79 break; 80 } 81 } 82 } 83 84 if (mnt == 0) { 85 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 86 /* 87 * Do an extra check to see if this is the root device. We 88 * can't trust /etc/mtab, and /proc/mounts will only list 89 * /dev/root for the root filesystem. Argh. Instead we 90 * check if the given device has the same major/minor number 91 * as the device that the root directory is on. 92 */ 93 if (file_rdev && stat("/", &st_buf) == 0) { 94 if (st_buf.st_dev == file_rdev) { 95 *mount_flags = EXT2_MF_MOUNTED; 96 if (mtpt) 97 strncpy(mtpt, "/", mtlen); 98 goto is_root; 99 } 100 } 101 #endif /* __GNU__ */ 102 goto errout; 103 } 104 #ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */ 105 /* Validate the entry in case /etc/mtab is out of date */ 106 /* 107 * We need to be paranoid, because some broken distributions 108 * (read: Slackware) don't initialize /etc/mtab before checking 109 * all of the non-root filesystems on the disk. 110 */ 111 if (stat(mnt->mnt_dir, &st_buf) < 0) { 112 retval = errno; 113 if (retval == ENOENT) { 114 #ifdef DEBUG 115 printf("Bogus entry in %s! (%s does not exist)\n", 116 mtab_file, mnt->mnt_dir); 117 #endif /* DEBUG */ 118 retval = 0; 119 } 120 goto errout; 121 } 122 if (file_rdev && (st_buf.st_dev != file_rdev)) { 123 #ifdef DEBUG 124 printf("Bogus entry in %s! (%s not mounted on %s)\n", 125 mtab_file, file, mnt->mnt_dir); 126 #endif /* DEBUG */ 127 goto errout; 128 } 129 #endif /* __GNU__ */ 130 *mount_flags = EXT2_MF_MOUNTED; 131 132 #ifdef MNTOPT_RO 133 /* Check to see if the ro option is set */ 134 if (hasmntopt(mnt, MNTOPT_RO)) 135 *mount_flags |= EXT2_MF_READONLY; 136 #endif 137 138 if (mtpt) 139 strncpy(mtpt, mnt->mnt_dir, mtlen); 140 /* 141 * Check to see if we're referring to the root filesystem. 142 * If so, do a manual check to see if we can open /etc/mtab 143 * read/write, since if the root is mounted read/only, the 144 * contents of /etc/mtab may not be accurate. 145 */ 146 if (!strcmp(mnt->mnt_dir, "/")) { 147 is_root: 148 #define TEST_FILE "/.ismount-test-file" 149 *mount_flags |= EXT2_MF_ISROOT; 150 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0600); 151 if (fd < 0) { 152 if (errno == EROFS) 153 *mount_flags |= EXT2_MF_READONLY; 154 } else 155 close(fd); 156 (void) unlink(TEST_FILE); 157 } 158 retval = 0; 159 errout: 160 endmntent (f); 161 return retval; 162 } 163 164 static errcode_t check_mntent(const char *file, int *mount_flags, 165 char *mtpt, int mtlen) 166 { 167 errcode_t retval; 168 169 #ifdef DEBUG 170 retval = check_mntent_file("/tmp/mtab", file, mount_flags, 171 mtpt, mtlen); 172 if (retval == 0) 173 return 0; 174 #endif /* DEBUG */ 175 #ifdef __linux__ 176 retval = check_mntent_file("/proc/mounts", file, mount_flags, 177 mtpt, mtlen); 178 if (retval == 0 && (*mount_flags != 0)) 179 return 0; 180 #endif /* __linux__ */ 181 #if defined(MOUNTED) || defined(_PATH_MOUNTED) 182 #ifndef MOUNTED 183 #define MOUNTED _PATH_MOUNTED 184 #endif /* MOUNTED */ 185 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); 186 return retval; 187 #else 188 *mount_flags = 0; 189 return 0; 190 #endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */ 191 } 192 193 #else 194 #if defined(HAVE_GETMNTINFO) 195 196 static errcode_t check_getmntinfo(const char *file, int *mount_flags, 197 char *mtpt, int mtlen) 198 { 199 struct statfs *mp; 200 int len, n; 201 const char *s1; 202 char *s2; 203 204 n = getmntinfo(&mp, MNT_NOWAIT); 205 if (n == 0) 206 return errno; 207 208 len = sizeof(_PATH_DEV) - 1; 209 s1 = file; 210 if (strncmp(_PATH_DEV, s1, len) == 0) 211 s1 += len; 212 213 *mount_flags = 0; 214 while (--n >= 0) { 215 s2 = mp->f_mntfromname; 216 if (strncmp(_PATH_DEV, s2, len) == 0) { 217 s2 += len - 1; 218 *s2 = 'r'; 219 } 220 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) { 221 *mount_flags = EXT2_MF_MOUNTED; 222 break; 223 } 224 ++mp; 225 } 226 if (mtpt) 227 strncpy(mtpt, mp->f_mntonname, mtlen); 228 return 0; 229 } 230 #endif /* HAVE_GETMNTINFO */ 231 #endif /* HAVE_MNTENT_H */ 232 233 /* 234 * Check to see if we're dealing with the swap device. 235 */ 236 static int is_swap_device(const char *file) 237 { 238 FILE *f; 239 char buf[1024], *cp; 240 dev_t file_dev; 241 struct stat st_buf; 242 int ret = 0; 243 244 file_dev = 0; 245 #ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 246 if ((stat(file, &st_buf) == 0) && 247 S_ISBLK(st_buf.st_mode)) 248 file_dev = st_buf.st_rdev; 249 #endif /* __GNU__ */ 250 251 if (!(f = fopen("/proc/swaps", "r"))) 252 return 0; 253 /* Skip the first line */ 254 fgets(buf, sizeof(buf), f); 255 while (!feof(f)) { 256 if (!fgets(buf, sizeof(buf), f)) 257 break; 258 if ((cp = strchr(buf, ' ')) != NULL) 259 *cp = 0; 260 if ((cp = strchr(buf, '\t')) != NULL) 261 *cp = 0; 262 if (strcmp(buf, file) == 0) { 263 ret++; 264 break; 265 } 266 #ifndef __GNU__ 267 if (file_dev && (stat(buf, &st_buf) == 0) && 268 S_ISBLK(st_buf.st_mode) && 269 file_dev == st_buf.st_rdev) { 270 ret++; 271 break; 272 } 273 #endif /* __GNU__ */ 274 } 275 fclose(f); 276 return ret; 277 } 278 279 280 /* 281 * ext2fs_check_mount_point() fills determines if the device is 282 * mounted or otherwise busy, and fills in mount_flags with one or 283 * more of the following flags: EXT2_MF_MOUNTED, EXT2_MF_ISROOT, 284 * EXT2_MF_READONLY, EXT2_MF_SWAP, and EXT2_MF_BUSY. If mtpt is 285 * non-NULL, the directory where the device is mounted is copied to 286 * where mtpt is pointing, up to mtlen characters. 287 */ 288 #ifdef __TURBOC__ 289 #pragma argsused 290 #endif 291 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, 292 char *mtpt, int mtlen) 293 { 294 struct stat st_buf; 295 errcode_t retval = 0; 296 int fd; 297 298 if (is_swap_device(device)) { 299 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP; 300 strncpy(mtpt, "<swap>", mtlen); 301 } else { 302 #ifdef HAVE_MNTENT_H 303 retval = check_mntent(device, mount_flags, mtpt, mtlen); 304 #else 305 #ifdef HAVE_GETMNTINFO 306 retval = check_getmntinfo(device, mount_flags, mtpt, mtlen); 307 #else 308 #ifdef __GNUC__ 309 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!" 310 #endif 311 *mount_flags = 0; 312 #endif /* HAVE_GETMNTINFO */ 313 #endif /* HAVE_MNTENT_H */ 314 } 315 if (retval) 316 return retval; 317 318 #ifdef __linux__ /* This only works on Linux 2.6+ systems */ 319 if ((stat(device, &st_buf) != 0) || 320 !S_ISBLK(st_buf.st_mode)) 321 return 0; 322 fd = open(device, O_RDONLY | O_EXCL); 323 if (fd < 0) { 324 if (errno == EBUSY) 325 *mount_flags |= EXT2_MF_BUSY; 326 } else 327 close(fd); 328 #endif 329 330 return 0; 331 } 332 333 /* 334 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED, 335 * EXT2_MF_READONLY, and EXT2_MF_ROOT 336 * 337 */ 338 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags) 339 { 340 return ext2fs_check_mount_point(file, mount_flags, NULL, 0); 341 } 342 343 #ifdef DEBUG 344 int main(int argc, char **argv) 345 { 346 int retval, mount_flags; 347 char mntpt[80]; 348 349 if (argc < 2) { 350 fprintf(stderr, "Usage: %s device\n", argv[0]); 351 exit(1); 352 } 353 354 mntpt[0] = 0; 355 retval = ext2fs_check_mount_point(argv[1], &mount_flags, 356 mntpt, sizeof(mntpt)); 357 if (retval) { 358 com_err(argv[0], retval, 359 "while calling ext2fs_check_if_mounted"); 360 exit(1); 361 } 362 printf("Device %s reports flags %02x\n", argv[1], mount_flags); 363 if (mount_flags & EXT2_MF_BUSY) 364 printf("\t%s is apparently in use.\n", argv[1]); 365 if (mount_flags & EXT2_MF_MOUNTED) 366 printf("\t%s is mounted.\n", argv[1]); 367 if (mount_flags & EXT2_MF_SWAP) 368 printf("\t%s is a swap device.\n", argv[1]); 369 if (mount_flags & EXT2_MF_READONLY) 370 printf("\t%s is read-only.\n", argv[1]); 371 if (mount_flags & EXT2_MF_ISROOT) 372 printf("\t%s is the root filesystem.\n", argv[1]); 373 if (mntpt[0]) 374 printf("\t%s is mounted on %s.\n", argv[1], mntpt); 375 exit(0); 376 } 377 #endif /* DEBUG */ 378
