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  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17  * General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  *
  23  */
  24
  25 #include <limits.h>
  26 #include <stdlib.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <stdio.h>
  31 #include <mntent.h>
  32 #include <ctype.h>
  33 #include <sys/mount.h>
  34 #include <fcntl.h>              // for CONFIG_FEATURE_MOUNT_LOOP
  35 #include <sys/ioctl.h>  // for CONFIG_FEATURE_MOUNT_LOOP
  36 #include "busybox.h"
  37
  38 /* This is just a warning of a common mistake.  Possibly this should be a
  39  * uclibc faq entry rather than in busybox... */
  40 #if ENABLE_NFSMOUNT && defined(__UCLIBC__) && ! defined(__UCLIBC_HAS_RPC__)
  41 #error "You need to build uClibc with UCLIBC_HAS_RPC for busybox mount with NFS support to compile."
  42 #endif
  43
  44 // These two aren't always defined in old headers
  45 #ifndef MS_BIND
  46 #define MS_BIND         4096
  47 #endif
  48 #ifndef MS_MOVE
  49 #define MS_MOVE         8192
  50 #endif
  51
  52 /* Consume standard mount options (from -o options or --options).
  53  * Set appropriate flags and collect unrecognized ones as a comma separated
  54  * string to pass to kernel */
  55
  56 struct {
  57         const char *name;
  58         long flags;
  59 } static const  mount_options[] = {
  60         {"loop", 0},
  61         {"defaults", 0},
  62         {"noauto", 0},
  63         {"ro", MS_RDONLY},
  64         {"rw", ~MS_RDONLY},
  65         {"nosuid", MS_NOSUID},
  66         {"suid", ~MS_NOSUID},
  67         {"dev", ~MS_NODEV},
  68         {"nodev", MS_NODEV},
  69         {"exec", ~MS_NOEXEC},
  70         {"noexec", MS_NOEXEC},
  71         {"sync", MS_SYNCHRONOUS},
  72         {"async", ~MS_SYNCHRONOUS},
  73         {"remount", MS_REMOUNT},
  74         {"atime", MS_NOATIME},
  75         {"noatime", MS_NOATIME},
  76         {"diratime", MS_NODIRATIME},
  77         {"nodiratime", MS_NODIRATIME},
  78         {"bind", MS_BIND},
  79         {"move", MS_MOVE}
  80 };
  81
  82 /* Uses the mount_options list above */
  83 static void parse_mount_options(char *options, int *flags, char **strflags)
  84 {
  85         // Loop through options
  86         for(;;) {
  87                 int i;
  88                 char *comma = strchr(options, ',');
  89
  90                 if(comma) *comma = 0;
  91
  92                 // Find this option in mount_options
  93                 for(i = 0; i < (sizeof(mount_options) / sizeof(*mount_options)); i++) {
  94                         if(!strcasecmp(mount_options[i].name, options)) {
  95                                 long fl = mount_options[i].flags;
  96                                 if(fl < 0) *flags &= fl;
  97                                 else *flags |= fl;
  98                                 break;
  99                         }
 100                 }
 101                 // Unrecognized mount option?
 102                 if(i == sizeof(mount_options)) {
 103                         // Add it to strflags, to pass on to kernel
 104                         i = *strflags ? strlen(*strflags) : 0;
 105                         *strflags = xrealloc(*strflags, i+strlen(options)+2);
 106                         // Comma separated if it's not the first one
 107                         if(i) (*strflags)[i] = ',';
 108                         strcpy((*strflags)+i, options);
 109                 }
 110                 // Advance to next option, or finish
 111                 if(comma) {
 112                         *comma = ',';
 113                         options = ++comma;
 114                 } else break;
 115         }
 116 }
 117
 118 /* This does the work */
 119
 120 extern int mount_main(int argc, char **argv)
 121 {
 122         char *string_flags = 0, *fsType = 0, *blockDevice = 0, *directory = 0,
 123                  *loopFile = 0, *buf = 0,
 124                  *files[] = {"/etc/filesystems", "/proc/filesystems", 0};
 125         int i, opt, all = FALSE, fakeIt = FALSE, allowWrite = FALSE,
 126                 rc = EXIT_FAILURE, useMtab = ENABLE_FEATURE_MTAB_SUPPORT;
 127         int flags=0xc0ed0000;   // Needed for linux 2.2, ignored by 2.4 and 2.6.
 128         FILE *file = 0,*f = 0;
 129         char path[PATH_MAX*2];
 130         struct mntent m;
 131         struct stat statbuf;
 132
 133         /* parse long options, like --bind and --move.  Note that -o option
 134          * and --option are synonymous.  Yes, this means --remount,rw works. */
 135
 136         for(i = opt = 0; i < argc; i++) {
 137                 if(argv[i][0] == '-' && argv[i][1] == '-')
 138                         parse_mount_options(argv[i]+2, &flags, &string_flags);
 139                 else argv[opt++] = argv[i];
 140         }
 141         argc = opt;
 142
 143         // Parse remaining options
 144
 145         while((opt = getopt(argc, argv, "o:t:rwafnv")) > 0) {
 146                 switch (opt) {
 147                 case 'o':
 148                         parse_mount_options(optarg, &flags, &string_flags);
 149                         break;
 150                 case 't':
 151                         fsType = optarg;
 152                         break;
 153                 case 'r':
 154                         flags |= MS_RDONLY;
 155                         break;
 156                 case 'w':
 157                         allowWrite=TRUE;
 158                         break;
 159                 case 'a':
 160                         all = TRUE;
 161                         break;
 162                 case 'f':
 163                         fakeIt = TRUE;
 164                         break;
 165                 case 'n':
 166                         useMtab = FALSE;
 167                         break;
 168                 case 'v':
 169                         break;          // ignore -v
 170                 default:
 171                         bb_show_usage();
 172                 }
 173         }
 174
 175         // If we have no arguments, show currently mounted filesystems
 176
 177         if(!all && (optind == argc)) {
 178                 FILE *mountTable = setmntent(bb_path_mtab_file, "r");
 179
 180                 if(!mountTable) bb_perror_msg_and_die(bb_path_mtab_file);
 181
 182                 while (getmntent_r(mountTable,&m,path,sizeof(path))) {
 183                         blockDevice = m.mnt_fsname;
 184
 185                         // Clean up display a little bit regarding root devie
 186                         if(!strcmp(blockDevice, "rootfs")) continue;
 187                         if(!strcmp(blockDevice, "/dev/root"))
 188                                 blockDevice = find_block_device("/");
 189
 190                         if(!fsType || !strcmp(m.mnt_type, fsType))
 191                                 printf("%s on %s type %s (%s)\n", blockDevice, m.mnt_dir,
 192                                            m.mnt_type, m.mnt_opts);
 193                         if(ENABLE_FEATURE_CLEAN_UP && blockDevice != m.mnt_fsname)
 194                                 free(blockDevice);
 195                 }
 196                 endmntent(mountTable);
 197                 return EXIT_SUCCESS;
 198         }
 199
 200         /* The next argument is what to mount.  if there's an argument after that
 201          * it's where to mount it.  If we're not mounting all, and we have both
 202          * of these arguments, jump straight to the actual mount. */
 203
 204         statbuf.st_mode=0;
 205         if(optind < argc)
 206                 blockDevice = !stat(argv[optind], &statbuf) ?
 207                                 bb_simplify_path(argv[optind]) :
 208                                 (ENABLE_FEATURE_CLEAN_UP ? strdup(argv[optind]) : argv[optind]);
 209         if(optind+1 < argc) directory = bb_simplify_path(argv[optind+1]);
 210
 211     // If we don't have to loop through fstab, skip ahead a bit.
 212
 213         if(!all && optind+1!=argc) goto singlemount;
 214
 215         // Loop through /etc/fstab entries to look up this entry.
 216
 217         if(!(file=setmntent("/etc/fstab","r")))
 218                 bb_perror_msg_and_die("\nCannot read /etc/fstab");
 219         for(;;) {
 220
 221                 // Get next fstab entry
 222
 223                 if(!getmntent_r(file,&m,path,sizeof(path))) {
 224                         if(!all)
 225                                 bb_perror_msg("Can't find %s in /etc/fstab\n", blockDevice);
 226                         break;
 227                 }
 228
 229                 // If we're mounting all and all doesn't mount this one, skip it.
 230
 231                 if(all) {
 232                         if(strstr(m.mnt_opts,"noauto") || strstr(m.mnt_type,"swap"))
 233                                 continue;
 234                         flags=0;
 235
 236                 /* If we're mounting something specific and this isn't it, skip it.
 237                  * Note we must match both the exact text in fstab (ala "proc") or
 238                  * a full path from root */
 239
 240                 } else if(strcmp(blockDevice,m.mnt_fsname) &&
 241                                   strcmp(argv[optind],m.mnt_fsname) &&
 242                                   strcmp(blockDevice,m.mnt_dir) &&
 243                                   strcmp(argv[optind],m.mnt_dir)) continue;
 244
 245                 /* Parse flags from /etc/fstab (unless this is a single mount
 246                  * overriding fstab -- note the "all" test above zeroed the flags,
 247                  * to prevent flags from previous entries affecting this one, so
 248                  * the only way we could get here with nonzero flags is a single
 249                  * mount). */
 250
 251                 if(!flags) {
 252                         if(ENABLE_FEATURE_CLEAN_UP) free(string_flags);
 253                         string_flags=NULL;
 254                         parse_mount_options(m.mnt_opts, &flags, &string_flags);
 255                 }
 256
 257                 /* Fill out remaining fields with info from mtab */
 258
 259                 if(ENABLE_FEATURE_CLEAN_UP) {
 260                         free(blockDevice);
 261                         blockDevice=strdup(m.mnt_fsname);
 262                         free(directory);
 263                         directory=strdup(m.mnt_type);
 264                 } else {
 265                         blockDevice=m.mnt_fsname;
 266                         directory=m.mnt_dir;
 267                 }
 268                 fsType=m.mnt_type;
 269
 270                 /* Ok, we're ready to actually mount a specific source on a specific
 271                  * directory now. */
 272
 273 singlemount:
 274
 275                 // If they said -w, override fstab
 276
 277                 if(allowWrite) flags&=~MS_RDONLY;
 278
 279                 // Might this be an NFS filesystem?
 280
 281                 if(ENABLE_NFSMOUNT && (!fsType || !strcmp(fsType,"nfs")) &&
 282                         strchr(blockDevice, ':') != NULL)
 283                 {
 284                         if(nfsmount(blockDevice, directory, &flags, &string_flags, 1))
 285                                 bb_perror_msg("nfsmount failed");
 286                         else {
 287                                 rc=EXIT_SUCCESS;
 288                                 fsType="nfs";
 289                         }
 290                 } else {
 291
 292                         // Do we need to allocate a loopback device?
 293
 294                         if(ENABLE_FEATURE_MOUNT_LOOP && !fakeIt && S_ISREG(statbuf.st_mode))
 295                         {
 296                                 loopFile = blockDevice;
 297                                 blockDevice = 0;
 298                                 switch(set_loop(&blockDevice, loopFile, 0)) {
 299                                         case 0:
 300                                         case 1:
 301                                                 break;
 302                                         default:
 303                                                 bb_error_msg_and_die(
 304                                                         errno == EPERM || errno == EACCES ?
 305                                                         bb_msg_perm_denied_are_you_root :
 306                                                         "Couldn't setup loop device");
 307                                                 break;
 308                                 }
 309                         }
 310
 311                         /* If we know the fstype (or don't need to), jump straight
 312                          * to the actual mount. */
 313
 314                         if(fsType || (flags & (MS_REMOUNT | MS_BIND | MS_MOVE)))
 315                                 goto mount_it_now;
 316                 }
 317
 318                 // Loop through filesystem types until mount succeeds or we run out
 319
 320                 for(i = 0; files[i] && rc; i++) {
 321                         f = fopen(files[i], "r");
 322                         if(!f) continue;
 323                         // Get next block device backed filesystem
 324                         for(buf = 0; (buf = fsType = bb_get_chomped_line_from_file(f));
 325                                         free(buf))
 326                         {
 327                                 // Skip funky entries in /proc
 328                                 if(!strncmp(buf,"nodev",5) && isspace(buf[5])) continue;
 329
 330                                 while(isspace(*fsType)) fsType++;
 331                                 if(*buf=='#' || *buf=='*') continue;
 332                                 if(!*fsType) continue;
 333 mount_it_now:
 334                                 // Okay, try to mount
 335
 336                                 if (!fakeIt) {
 337                                         for(;;) {
 338                                                 rc = mount(blockDevice, directory, fsType, flags, string_flags);
 339                                                 if(!rc || (flags&MS_RDONLY) || (errno!=EACCES && errno!=EROFS))
 340                                                         break;
 341                                                 bb_error_msg("%s is write-protected, mounting read-only", blockDevice);
 342                                                 flags|=MS_RDONLY;
 343                                         }
 344                                 }
 345                                 if(!rc) break;
 346                         }
 347                         if(f) fclose(f);
 348                         if(!f || !rc) break;
 349                 }
 350
 351                 /* If the mount was sucessful, and we're maintaining an old-style
 352                  * mtab file by hand, add new entry to it now. */
 353                 if((!rc || fakeIt) && useMtab) {
 354                         FILE *mountTable = setmntent(bb_path_mtab_file, "a+");
 355
 356                         if(!mountTable) bb_perror_msg(bb_path_mtab_file);
 357                         else {
 358                                 // Remove trailing / (if any) from directory we mounted on
 359                                 int length=strlen(directory);
 360                                 if(length>1 && directory[length-1] == '/')
 361                                         directory[length-1]=0;
 362
 363                                 // Fill out structure (should be ok to re-use existing one).
 364                                 m.mnt_fsname=blockDevice;
 365                                 m.mnt_dir=directory;
 366                                 m.mnt_type=fsType ? : "--bind";
 367                                 m.mnt_opts=string_flags ? :
 368                                         ((flags & MS_RDONLY) ? "ro" : "rw");
 369                                 m.mnt_freq = 0;
 370                                 m.mnt_passno = 0;
 371
 372                                 // Write and close
 373                                 addmntent(mountTable, &m);
 374                                 endmntent(mountTable);
 375                         }
 376                 } else {
 377                         // Mount failed.  Clean up
 378                         if(loopFile) {
 379                                 del_loop(blockDevice);
 380                                 if(ENABLE_FEATURE_CLEAN_UP) free(loopFile);
 381                         }
 382                         // Don't whine about already mounted fs when mounting all.
 383                         if(rc<0 && errno == EBUSY && all) rc=0;
 384                         else if (errno == EPERM)
 385                                 bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
 386                 }
 387                 // We couldn't free this earlier becase fsType could be in buf.
 388                 if(ENABLE_FEATURE_CLEAN_UP) {
 389                         free(buf);
 390                         free(blockDevice);
 391                         free(directory);
 392                 }
 393                 if(!all) break;
 394         }
 395
 396         if(file) endmntent(file);
 397         if(rc) bb_perror_msg("Mounting %s on %s failed", blockDevice, directory);
 398
 399         return rc ? : EXIT_FAILURE;
 400 }