release/src/router/busybox/e2fsprogs/old_e2fsprogs/ext2fs/ismounted.c

   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  */
  44 static 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, '/')) {
 148 is_root:
 149 #define TEST_FILE "/.ismount-test-file"
 150                 *mount_flags |= EXT2_MF_ISROOT;
 151                 fd = open(TEST_FILE, O_RDWR|O_CREAT, 0777);
 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;
 160 errout:
 161         endmntent (f);
 162         return retval;
 163 }
 164
 165 static 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         return retval;
 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_for_read("/proc/swaps")))
 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() returns 1 if the device is mounted, 0
 282  * otherwise.  If mtpt is non-NULL, the directory where the device is
 283  * mounted is copied to where mtpt is pointing, up to mtlen
 284  * characters.
 285  */
 286 #ifdef __TURBOC__
 287 # pragma argsused
 288 #endif
 289 errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
 290                                   char *mtpt, int mtlen)
 291 {
 292         if (is_swap_device(device)) {
 293                 *mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
 294                 strncpy(mtpt, "<swap>", mtlen);
 295                 return 0;
 296         }
 297 #ifdef HAVE_MNTENT_H
 298         return check_mntent(device, mount_flags, mtpt, mtlen);
 299 #else
 300 #ifdef HAVE_GETMNTINFO
 301         return check_getmntinfo(device, mount_flags, mtpt, mtlen);
 302 #else
 303 #ifdef __GNUC__
 304  #warning "Can't use getmntent or getmntinfo to check for mounted filesystems!"
 305 #endif
 306         *mount_flags = 0;
 307         return 0;
 308 #endif /* HAVE_GETMNTINFO */
 309 #endif /* HAVE_MNTENT_H */
 310 }
 311
 312 /*
 313  * ext2fs_check_if_mounted() sets the mount_flags EXT2_MF_MOUNTED,
 314  * EXT2_MF_READONLY, and EXT2_MF_ROOT
 315  *
 316  */
 317 errcode_t ext2fs_check_if_mounted(const char *file, int *mount_flags)
 318 {
 319         return ext2fs_check_mount_point(file, mount_flags, NULL, 0);
 320 }
 321
 322 #ifdef DEBUG
 323 int main(int argc, char **argv)
 324 {
 325         int     retval, mount_flags;
 326         char    mntpt[80];
 327
 328         if (argc < 2) {
 329                 fprintf(stderr, "Usage: %s device\n", argv[0]);
 330                 exit(1);
 331         }
 332
 333         mntpt[0] = 0;
 334         retval = ext2fs_check_mount_point(argv[1], &mount_flags,
 335                                           mntpt, sizeof(mntpt));
 336         if (retval) {
 337                 com_err(argv[0], retval,
 338                         "while calling ext2fs_check_if_mounted");
 339                 exit(1);
 340         }
 341         printf("Device %s reports flags %02x\n", argv[1], mount_flags);
 342         if (mount_flags & EXT2_MF_BUSY)
 343                 printf("\t%s is apparently in use.\n", argv[1]);
 344         if (mount_flags & EXT2_MF_MOUNTED)
 345                 printf("\t%s is mounted.\n", argv[1]);
 346         if (mount_flags & EXT2_MF_SWAP)
 347                 printf("\t%s is a swap device.\n", argv[1]);
 348         if (mount_flags & EXT2_MF_READONLY)
 349                 printf("\t%s is read-only.\n", argv[1]);
 350         if (mount_flags & EXT2_MF_ISROOT)
 351                 printf("\t%s is the root filesystem.\n", argv[1]);
 352         if (mntpt[0])
 353                 printf("\t%s is mounted on %s.\n", argv[1], mntpt);
 354         exit(0);
 355 }
 356 #endif /* DEBUG */