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 == 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 } 165 166 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) 197 198 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 */ 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 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 */ 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 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
