1/* vi: set sw=4 ts=4: */ 2/* 3 * ismounted.c --- Check to see if the filesystem was mounted 4 * 5 * Copyright (C) 1995,1996,1997,1998,1999,2000 Theodore Ts'o. 6 * 7 * %Begin-Header% 8 * This file may be redistributed under the terms of the GNU Public 9 * License. 10 * %End-Header% 11 */ 12 13#include <stdio.h> 14#if HAVE_UNISTD_H 15#include <unistd.h> 16#endif 17#if HAVE_ERRNO_H 18#include <errno.h> 19#endif 20#include <fcntl.h> 21#ifdef HAVE_LINUX_FD_H 22#include <linux/fd.h> 23#endif 24#ifdef HAVE_MNTENT_H 25#include <mntent.h> 26#endif 27#ifdef HAVE_GETMNTINFO 28#include <paths.h> 29#include <sys/param.h> 30#include <sys/mount.h> 31#endif /* HAVE_GETMNTINFO */ 32#include <string.h> 33#include <sys/stat.h> 34 35#include "ext2_fs.h" 36#include "ext2fs.h" 37 38#ifdef HAVE_MNTENT_H 39/* 40 * Helper function which checks a file in /etc/mtab format to see if a 41 * filesystem is mounted. Returns an error if the file doesn't exist 42 * or can't be opened. 43 */ 44static errcode_t check_mntent_file(const char *mtab_file, const char *file, 45 int *mount_flags, char *mtpt, int mtlen) 46{ 47 struct mntent *mnt; 48 struct stat st_buf; 49 errcode_t retval = 0; 50 dev_t file_dev=0, file_rdev=0; 51 ino_t file_ino=0; 52 FILE *f; 53 int fd; 54 55 *mount_flags = 0; 56 if ((f = setmntent (mtab_file, "r")) == NULL) 57 return errno; 58 if (stat(file, &st_buf) == 0) { 59 if (S_ISBLK(st_buf.st_mode)) { 60#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 61 file_rdev = st_buf.st_rdev; 62#endif /* __GNU__ */ 63 } else { 64 file_dev = st_buf.st_dev; 65 file_ino = st_buf.st_ino; 66 } 67 } 68 while ((mnt = getmntent (f)) != NULL) { 69 if (strcmp(file, mnt->mnt_fsname) == 0) 70 break; 71 if (stat(mnt->mnt_fsname, &st_buf) == 0) { 72 if (S_ISBLK(st_buf.st_mode)) { 73#ifndef __GNU__ 74 if (file_rdev && (file_rdev == st_buf.st_rdev)) 75 break; 76#endif /* __GNU__ */ 77 } else { 78 if (file_dev && ((file_dev == st_buf.st_dev) && 79 (file_ino == st_buf.st_ino))) 80 break; 81 } 82 } 83 } 84 85 if (mnt == 0) { 86#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 87 /* 88 * Do an extra check to see if this is the root device. We 89 * can't trust /etc/mtab, and /proc/mounts will only list 90 * /dev/root for the root filesystem. Argh. Instead we 91 * check if the given device has the same major/minor number 92 * as the device that the root directory is on. 93 */ 94 if (file_rdev && stat("/", &st_buf) == 0) { 95 if (st_buf.st_dev == file_rdev) { 96 *mount_flags = EXT2_MF_MOUNTED; 97 if (mtpt) 98 strncpy(mtpt, "/", mtlen); 99 goto is_root; 100 } 101 } 102#endif /* __GNU__ */ 103 goto errout; 104 } 105#ifndef __GNU__ /* The GNU hurd is deficient; what else is new? */ 106 /* Validate the entry in case /etc/mtab is out of date */ 107 /* 108 * We need to be paranoid, because some broken distributions 109 * (read: Slackware) don't initialize /etc/mtab before checking 110 * all of the non-root filesystems on the disk. 111 */ 112 if (stat(mnt->mnt_dir, &st_buf) < 0) { 113 retval = errno; 114 if (retval == ENOENT) { 115#ifdef DEBUG 116 printf("Bogus entry in %s! (%s does not exist)\n", 117 mtab_file, mnt->mnt_dir); 118#endif /* DEBUG */ 119 retval = 0; 120 } 121 goto errout; 122 } 123 if (file_rdev && (st_buf.st_dev != file_rdev)) { 124#ifdef DEBUG 125 printf("Bogus entry in %s! (%s not mounted on %s)\n", 126 mtab_file, file, mnt->mnt_dir); 127#endif /* DEBUG */ 128 goto errout; 129 } 130#endif /* __GNU__ */ 131 *mount_flags = EXT2_MF_MOUNTED; 132 133#ifdef MNTOPT_RO 134 /* Check to see if the ro option is set */ 135 if (hasmntopt(mnt, MNTOPT_RO)) 136 *mount_flags |= EXT2_MF_READONLY; 137#endif 138 139 if (mtpt) 140 strncpy(mtpt, mnt->mnt_dir, mtlen); 141 /* 142 * Check to see if we're referring to the root filesystem. 143 * If so, do a manual check to see if we can open /etc/mtab 144 * read/write, since if the root is mounted read/only, the 145 * contents of /etc/mtab may not be accurate. 146 */ 147 if (LONE_CHAR(mnt->mnt_dir, '/')) { 148is_root: 149#define TEST_FILE "/.ismount-test-file" 150 *mount_flags |= EXT2_MF_ISROOT; 151 fd = open(TEST_FILE, O_RDWR|O_CREAT); 152 if (fd < 0) { 153 if (errno == EROFS) 154 *mount_flags |= EXT2_MF_READONLY; 155 } else 156 close(fd); 157 (void) unlink(TEST_FILE); 158 } 159 retval = 0; 160errout: 161 endmntent (f); 162 return retval; 163} 164 165static errcode_t check_mntent(const char *file, int *mount_flags, 166 char *mtpt, int mtlen) 167{ 168 errcode_t retval; 169 170#ifdef DEBUG 171 retval = check_mntent_file("/tmp/mtab", file, mount_flags, 172 mtpt, mtlen); 173 if (retval == 0) 174 return 0; 175#endif /* DEBUG */ 176#ifdef __linux__ 177 retval = check_mntent_file("/proc/mounts", file, mount_flags, 178 mtpt, mtlen); 179 if (retval == 0 && (*mount_flags != 0)) 180 return 0; 181#endif /* __linux__ */ 182#if defined(MOUNTED) || defined(_PATH_MOUNTED) 183#ifndef MOUNTED 184#define MOUNTED _PATH_MOUNTED 185#endif /* MOUNTED */ 186 retval = check_mntent_file(MOUNTED, file, mount_flags, mtpt, mtlen); 187 return retval; 188#else 189 *mount_flags = 0; 190 return 0; 191#endif /* defined(MOUNTED) || defined(_PATH_MOUNTED) */ 192} 193 194#else 195#if defined(HAVE_GETMNTINFO) 196 197static errcode_t check_getmntinfo(const char *file, int *mount_flags, 198 char *mtpt, int mtlen) 199{ 200 struct statfs *mp; 201 int len, n; 202 const char *s1; 203 char *s2; 204 205 n = getmntinfo(&mp, MNT_NOWAIT); 206 if (n == 0) 207 return errno; 208 209 len = sizeof(_PATH_DEV) - 1; 210 s1 = file; 211 if (strncmp(_PATH_DEV, s1, len) == 0) 212 s1 += len; 213 214 *mount_flags = 0; 215 while (--n >= 0) { 216 s2 = mp->f_mntfromname; 217 if (strncmp(_PATH_DEV, s2, len) == 0) { 218 s2 += len - 1; 219 *s2 = 'r'; 220 } 221 if (strcmp(s1, s2) == 0 || strcmp(s1, &s2[1]) == 0) { 222 *mount_flags = EXT2_MF_MOUNTED; 223 break; 224 } 225 ++mp; 226 } 227 if (mtpt) 228 strncpy(mtpt, mp->f_mntonname, mtlen); 229 return 0; 230} 231#endif /* HAVE_GETMNTINFO */ 232#endif /* HAVE_MNTENT_H */ 233 234/* 235 * Check to see if we're dealing with the swap device. 236 */ 237static int is_swap_device(const char *file) 238{ 239 FILE *f; 240 char buf[1024], *cp; 241 dev_t file_dev; 242 struct stat st_buf; 243 int ret = 0; 244 245 file_dev = 0; 246#ifndef __GNU__ /* The GNU hurd is broken with respect to stat devices */ 247 if ((stat(file, &st_buf) == 0) && 248 S_ISBLK(st_buf.st_mode)) 249 file_dev = st_buf.st_rdev; 250#endif /* __GNU__ */ 251 252 if (!(f = fopen("/proc/swaps", "r"))) 253 return 0; 254 /* Skip the first line */ 255 fgets(buf, sizeof(buf), f); 256 while (!feof(f)) { 257 if (!fgets(buf, sizeof(buf), f)) 258 break; 259 if ((cp = strchr(buf, ' ')) != NULL) 260 *cp = 0; 261 if ((cp = strchr(buf, '\t')) != NULL) 262 *cp = 0; 263 if (strcmp(buf, file) == 0) { 264 ret++; 265 break; 266 } 267#ifndef __GNU__ 268 if (file_dev && (stat(buf, &st_buf) == 0) && 269 S_ISBLK(st_buf.st_mode) && 270 file_dev == st_buf.st_rdev) { 271 ret++; 272 break; 273 } 274#endif /* __GNU__ */ 275 } 276 fclose(f); 277 return ret; 278} 279 280 281/* 282 * ext2fs_check_mount_point() returns 1 if the device is mounted, 0 283 * otherwise. If mtpt is non-NULL, the directory where the device is 284 * mounted is copied to where mtpt is pointing, up to mtlen 285 * characters. 286 */ 287#ifdef __TURBOC__ 288# pragma argsused 289#endif 290errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags, 291 char *mtpt, int mtlen) 292{ 293 if (is_swap_device(device)) { 294 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP; 295 strncpy(mtpt, "<swap>", mtlen); 296 return 0; 297 } 298#ifdef HAVE_MNTENT_H 299 return check_mntent(device, mount_flags, mtpt, mtlen); 300#else 301#ifdef HAVE_GETMNTINFO 302 return check_getmntinfo(device, mount_flags, mtpt, mtlen); 303#else 304#ifdef __GNUC__ 305 #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!" 306#endif 307 *mount_flags = 0; 308 return 0; 309#endif /* HAVE_GETMNTINFO */ 310#endif /* HAVE_MNTENT_H */ 311} 312 313/* 314 * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED, 315 * EXT2_MF_READONLY, and EXT2_MF_ROOT 316 * 317 */ 318errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags) 319{ 320 return ext2fs_check_mount_point(file, mount_flags, NULL, 0); 321} 322 323#ifdef DEBUG 324int main(int argc, char **argv) 325{ 326 int retval, mount_flags; 327 char mntpt[80]; 328 329 if (argc < 2) { 330 fprintf(stderr, "Usage: %s device\n", argv[0]); 331 exit(1); 332 } 333 334 mntpt[0] = 0; 335 retval = ext2fs_check_mount_point(argv[1], &mount_flags, 336 mntpt, sizeof(mntpt)); 337 if (retval) { 338 com_err(argv[0], retval, 339 "while calling ext2fs_check_if_mounted"); 340 exit(1); 341 } 342 printf("Device %s reports flags %02x\n", argv[1], mount_flags); 343 if (mount_flags & EXT2_MF_BUSY) 344 printf("\t%s is apparently in use.\n", argv[1]); 345 if (mount_flags & EXT2_MF_MOUNTED) 346 printf("\t%s is mounted.\n", argv[1]); 347 if (mount_flags & EXT2_MF_SWAP) 348 printf("\t%s is a swap device.\n", argv[1]); 349 if (mount_flags & EXT2_MF_READONLY) 350 printf("\t%s is read-only.\n", argv[1]); 351 if (mount_flags & EXT2_MF_ISROOT) 352 printf("\t%s is the root filesystem.\n", argv[1]); 353 if (mntpt[0]) 354 printf("\t%s is mounted on %s.\n", argv[1], mntpt); 355 exit(0); 356} 357#endif /* DEBUG */ 358