util-linux/mount.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini mount implementation for busybox
   4  *
   5  * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
   6  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   7  * Copyright (C) 2005 by Rob Landley <rob@landley.net>
   8  *
   9  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  10  */
  11
  12 #include <limits.h>
  13 #include <stdlib.h>
  14 #include <unistd.h>
  15 #include <errno.h>
  16 #include <string.h>
  17 #include <stdio.h>
  18 #include <mntent.h>
  19 #include <ctype.h>
  20 #include <sys/mount.h>
  21 #include <fcntl.h>              // for CONFIG_FEATURE_MOUNT_LOOP
  22 #include <sys/ioctl.h>  // for CONFIG_FEATURE_MOUNT_LOOP
  23 #include "busybox.h"
  24
  25 // These two aren't always defined in old headers
  26 #ifndef MS_BIND
  27 #define MS_BIND         4096
  28 #endif
  29 #ifndef MS_MOVE
  30 #define MS_MOVE         8192
  31 #endif
  32
  33 /* Consume standard mount options (from -o options or --options).
  34  * Set appropriate flags and collect unrecognized ones as a comma separated
  35  * string to pass to kernel */
  36
  37 struct {
  38         const char *name;
  39         long flags;
  40 } static const  mount_options[] = {
  41         {"loop", 0},
  42         {"defaults", 0},
  43         {"noauto", 0},
  44         {"ro", MS_RDONLY},
  45         {"rw", ~MS_RDONLY},
  46         {"nosuid", MS_NOSUID},
  47         {"suid", ~MS_NOSUID},
  48         {"dev", ~MS_NODEV},
  49         {"nodev", MS_NODEV},
  50         {"exec", ~MS_NOEXEC},
  51         {"noexec", MS_NOEXEC},
  52         {"sync", MS_SYNCHRONOUS},
  53         {"async", ~MS_SYNCHRONOUS},
  54         {"remount", MS_REMOUNT},
  55         {"atime", ~MS_NOATIME},
  56         {"noatime", MS_NOATIME},
  57         {"diratime", ~MS_NODIRATIME},
  58         {"nodiratime", MS_NODIRATIME},
  59         {"bind", MS_BIND},
  60         {"move", MS_MOVE}
  61 };
  62
  63 /* Uses the mount_options list above */
  64 static void parse_mount_options(char *options, int *flags, char **strflags)
  65 {
  66         // Loop through options
  67         for(;;) {
  68                 int i;
  69                 char *comma = strchr(options, ',');
  70
  71                 if(comma) *comma = 0;
  72
  73                 // Find this option in mount_options
  74                 for(i = 0; i < (sizeof(mount_options) / sizeof(*mount_options)); i++) {
  75                         if(!strcasecmp(mount_options[i].name, options)) {
  76                                 long fl = mount_options[i].flags;
  77                                 if(fl < 0) *flags &= fl;
  78                                 else *flags |= fl;
  79                                 break;
  80                         }
  81                 }
  82                 // Unrecognized mount option?
  83                 if(i == (sizeof(mount_options) / sizeof(*mount_options))) {
  84                         // Add it to strflags, to pass on to kernel
  85                         i = *strflags ? strlen(*strflags) : 0;
  86                         *strflags = xrealloc(*strflags, i+strlen(options)+2);
  87                         // Comma separated if it's not the first one
  88                         if(i) (*strflags)[i++] = ',';
  89                         strcpy((*strflags)+i, options);
  90                 }
  91                 // Advance to next option, or finish
  92                 if(comma) {
  93                         *comma = ',';
  94                         options = ++comma;
  95                 } else break;
  96         }
  97 }
  98
  99 /* This does the work */
 100
 101 extern int mount_main(int argc, char **argv)
 102 {
 103         char *string_flags = 0, *fsType = 0, *blockDevice = 0, *directory = 0,
 104                  *loopFile = 0, *buf = 0,
 105                  *files[] = {"/etc/filesystems", "/proc/filesystems", 0};
 106         int i, opt, all = FALSE, fakeIt = FALSE, allowWrite = FALSE,
 107                 rc = 1, useMtab = ENABLE_FEATURE_MTAB_SUPPORT;
 108         int flags=0xc0ed0000;   // Needed for linux 2.2, ignored by 2.4 and 2.6.
 109         FILE *file = 0,*f = 0;
 110         char path[PATH_MAX*2];
 111         struct mntent m;
 112         struct stat statbuf;
 113
 114         /* parse long options, like --bind and --move.  Note that -o option
 115          * and --option are synonymous.  Yes, this means --remount,rw works. */
 116
 117         for(i = opt = 0; i < argc; i++) {
 118                 if(argv[i][0] == '-' && argv[i][1] == '-')
 119                         parse_mount_options(argv[i]+2, &flags, &string_flags);
 120                 else argv[opt++] = argv[i];
 121         }
 122         argc = opt;
 123
 124         // Parse remaining options
 125
 126         while((opt = getopt(argc, argv, "o:t:rwafnv")) > 0) {
 127                 switch (opt) {
 128                 case 'o':
 129                         parse_mount_options(optarg, &flags, &string_flags);
 130                         break;
 131                 case 't':
 132                         fsType = optarg;
 133                         break;
 134                 case 'r':
 135                         flags |= MS_RDONLY;
 136                         break;
 137                 case 'w':
 138                         allowWrite=TRUE;
 139                         break;
 140                 case 'a':
 141                         all = TRUE;
 142                         break;
 143                 case 'f':
 144                         fakeIt = TRUE;
 145                         break;
 146                 case 'n':
 147                         useMtab = FALSE;
 148                         break;
 149                 case 'v':
 150                         break;          // ignore -v
 151                 default:
 152                         bb_show_usage();
 153                 }
 154         }
 155
 156         // If we have no arguments, show currently mounted filesystems
 157
 158         if(!all && (optind == argc)) {
 159                 FILE *mountTable = setmntent(bb_path_mtab_file, "r");
 160
 161                 if(!mountTable) bb_perror_msg_and_die(bb_path_mtab_file);
 162
 163                 while (getmntent_r(mountTable,&m,path,sizeof(path))) {
 164                         blockDevice = m.mnt_fsname;
 165
 166                         // Clean up display a little bit regarding root device
 167                         if(!strcmp(blockDevice, "rootfs")) continue;
 168                         if(!strcmp(blockDevice, "/dev/root"))
 169                                 blockDevice = find_block_device("/");
 170
 171                         if(!fsType || !strcmp(m.mnt_type, fsType))
 172                                 printf("%s on %s type %s (%s)\n", blockDevice, m.mnt_dir,
 173                                            m.mnt_type, m.mnt_opts);
 174                         if(ENABLE_FEATURE_CLEAN_UP && blockDevice != m.mnt_fsname)
 175                                 free(blockDevice);
 176                 }
 177                 endmntent(mountTable);
 178                 return EXIT_SUCCESS;
 179         }
 180
 181         /* The next argument is what to mount.  if there's an argument after that
 182          * it's where to mount it.  If we're not mounting all, and we have both
 183          * of these arguments, jump straight to the actual mount. */
 184
 185         statbuf.st_mode=0;
 186         if(optind < argc)
 187                 blockDevice = !stat(argv[optind], &statbuf) ?
 188                                 bb_simplify_path(argv[optind]) :
 189                                 (ENABLE_FEATURE_CLEAN_UP ? strdup(argv[optind]) : argv[optind]);
 190         if(optind+1 < argc) directory = bb_simplify_path(argv[optind+1]);
 191
 192     // If we don't have to loop through fstab, skip ahead a bit.
 193
 194         if(!all && optind+1!=argc) goto singlemount;
 195
 196         // Loop through /etc/fstab entries to look up this entry.
 197
 198         if(!(file=setmntent("/etc/fstab","r")))
 199                 bb_perror_msg_and_die("\nCannot read /etc/fstab");
 200         for(;;) {
 201
 202                 // Get next fstab entry
 203
 204                 if(!getmntent_r(file,&m,path,sizeof(path))) {
 205                         if(!all)
 206                                 bb_perror_msg("Can't find %s in /etc/fstab\n", blockDevice);
 207                         break;
 208                 }
 209
 210                 // If we're mounting all and all doesn't mount this one, skip it.
 211
 212                 if(all) {
 213                         if(strstr(m.mnt_opts,"noauto") || strstr(m.mnt_type,"swap"))
 214                                 continue;
 215                         flags=0;
 216
 217                 /* If we're mounting something specific and this isn't it, skip it.
 218                  * Note we must match both the exact text in fstab (ala "proc") or
 219                  * a full path from root */
 220
 221                 } else if(strcmp(blockDevice,m.mnt_fsname) &&
 222                                   strcmp(argv[optind],m.mnt_fsname) &&
 223                                   strcmp(blockDevice,m.mnt_dir) &&
 224                                   strcmp(argv[optind],m.mnt_dir)) continue;
 225
 226                 /* Parse flags from /etc/fstab (unless this is a single mount
 227                  * overriding fstab -- note the "all" test above zeroed the flags,
 228                  * to prevent flags from previous entries affecting this one, so
 229                  * the only way we could get here with nonzero flags is a single
 230                  * mount). */
 231
 232                 if(!flags) {
 233                         if(ENABLE_FEATURE_CLEAN_UP) free(string_flags);
 234                         string_flags=NULL;
 235                         parse_mount_options(m.mnt_opts, &flags, &string_flags);
 236                 }
 237
 238                 /* Fill out remaining fields with info from mtab */
 239
 240                 if(ENABLE_FEATURE_CLEAN_UP) {
 241                         free(blockDevice);
 242                         blockDevice=strdup(m.mnt_fsname);
 243                         free(directory);
 244                         directory=strdup(m.mnt_dir);
 245                 } else {
 246                         blockDevice=m.mnt_fsname;
 247                         directory=m.mnt_dir;
 248                 }
 249                 fsType=m.mnt_type;
 250
 251                 /* Ok, we're ready to actually mount a specific source on a specific
 252                  * directory now. */
 253
 254 singlemount:
 255
 256                 // If they said -w, override fstab
 257
 258                 if(allowWrite) flags&=~MS_RDONLY;
 259
 260                 // Might this be an NFS filesystem?
 261
 262                 if(ENABLE_FEATURE_MOUNT_NFS && (!fsType || !strcmp(fsType,"nfs")) &&
 263                         strchr(blockDevice, ':') != NULL)
 264                 {
 265                         if(nfsmount(blockDevice, directory, &flags, &string_flags, 1))
 266                                 bb_perror_msg("nfsmount failed");
 267                         else {
 268                                 rc = 0;
 269                                 fsType="nfs";
 270                                 // Strangely enough, nfsmount() doesn't actually mount()
 271                                 goto mount_it_now;
 272                         }
 273                 } else {
 274
 275                         // Do we need to allocate a loopback device?
 276
 277                         if(ENABLE_FEATURE_MOUNT_LOOP && !fakeIt && S_ISREG(statbuf.st_mode))
 278                         {
 279                                 loopFile = blockDevice;
 280                                 blockDevice = 0;
 281                                 switch(set_loop(&blockDevice, loopFile, 0)) {
 282                                         case 0:
 283                                         case 1:
 284                                                 break;
 285                                         default:
 286                                                 bb_error_msg_and_die(
 287                                                         errno == EPERM || errno == EACCES ?
 288                                                         bb_msg_perm_denied_are_you_root :
 289                                                         "Couldn't setup loop device");
 290                                                 break;
 291                                 }
 292                         }
 293
 294                         /* If we know the fstype (or don't need to), jump straight
 295                          * to the actual mount. */
 296
 297                         if(fsType || (flags & (MS_REMOUNT | MS_BIND | MS_MOVE)))
 298                                 goto mount_it_now;
 299                 }
 300
 301                 // Loop through filesystem types until mount succeeds or we run out
 302
 303                 for(i = 0; files[i] && rc; i++) {
 304                         f = fopen(files[i], "r");
 305                         if(!f) continue;
 306                         // Get next block device backed filesystem
 307                         for(buf = 0; (buf = fsType = bb_get_chomped_line_from_file(f));
 308                                         free(buf))
 309                         {
 310                                 // Skip funky entries in /proc
 311                                 if(!strncmp(buf,"nodev",5) && isspace(buf[5])) continue;
 312
 313                                 while(isspace(*fsType)) fsType++;
 314                                 if(*buf=='#' || *buf=='*') continue;
 315                                 if(!*fsType) continue;
 316 mount_it_now:
 317                                 // Okay, try to mount
 318
 319                                 if (!fakeIt) {
 320                                         for(;;) {
 321                                                 rc = mount(blockDevice, directory, fsType, flags, string_flags);
 322                                                 if(!rc || (flags&MS_RDONLY) || (errno!=EACCES && errno!=EROFS))
 323                                                         break;
 324                                                 bb_error_msg("%s is write-protected, mounting read-only", blockDevice);
 325                                                 flags|=MS_RDONLY;
 326                                         }
 327                                 }
 328                                 if(!rc || !f) break;
 329                         }
 330                         if(!f) break;
 331                         fclose(f);
 332                         // goto mount_it_now with -a can jump past the initialization
 333                         f=0;
 334                         if(!rc) break;
 335                 }
 336
 337                 /* If the mount was successful, and we're maintaining an old-style
 338                  * mtab file by hand, add new entry to it now. */
 339                 if((!rc || fakeIt) && useMtab) {
 340                         FILE *mountTable = setmntent(bb_path_mtab_file, "a+");
 341
 342                         if(!mountTable) bb_perror_msg(bb_path_mtab_file);
 343                         else {
 344                                 // Remove trailing / (if any) from directory we mounted on
 345                                 int length=strlen(directory);
 346                                 if(length>1 && directory[length-1] == '/')
 347                                         directory[length-1]=0;
 348
 349                                 // Fill out structure (should be ok to re-use existing one).
 350                                 m.mnt_fsname=blockDevice;
 351                                 m.mnt_dir=directory;
 352                                 m.mnt_type=fsType ? : "--bind";
 353                                 m.mnt_opts=string_flags ? :
 354                                         ((flags & MS_RDONLY) ? "ro" : "rw");
 355                                 m.mnt_freq = 0;
 356                                 m.mnt_passno = 0;
 357
 358                                 // Write and close
 359                                 addmntent(mountTable, &m);
 360                                 endmntent(mountTable);
 361                         }
 362                 } else {
 363                         // Mount failed.  Clean up
 364                         if(loopFile) {
 365                                 del_loop(blockDevice);
 366                                 if(ENABLE_FEATURE_CLEAN_UP) free(loopFile);
 367                         }
 368                         // Don't whine about already mounted fs when mounting all.
 369                         if(rc<0 && errno == EBUSY && all) rc = 0;
 370                         else if (errno == EPERM)
 371                                 bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
 372                 }
 373                 // We couldn't free this earlier becase fsType could be in buf.
 374                 if(ENABLE_FEATURE_CLEAN_UP) free(buf);
 375                 if(!all) break;
 376         }
 377
 378         if(file) endmntent(file);
 379         if(rc) bb_perror_msg("Mounting %s on %s failed", blockDevice, directory);
 380         if(ENABLE_FEATURE_CLEAN_UP) {
 381                 free(blockDevice);
 382                 free(directory);
 383         }
 384
 385         return rc;
 386 }