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  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  *
  21  * 3/21/1999    Charles P. Wright <cpwright@cpwright.com>
  22  *              searches through fstab when -a is passed
  23  *              will try mounting stuff with all fses when passed -t auto
  24  *
  25  * 1999-04-17   Dave Cinege...Rewrote -t auto. Fixed ro mtab.
  26  *
  27  * 1999-10-07   Erik Andersen <andersen@lineo.com>, <andersee@debian.org>.
  28  *              Rewrite of a lot of code. Removed mtab usage (I plan on
  29  *              putting it back as a compile-time option some time),
  30  *              major adjustments to option parsing, and some serious
  31  *              dieting all around.
  32  *
  33  * 1999-11-06   mtab suppport is back - andersee
  34  *
  35  * 2000-01-12   Ben Collins <bcollins@debian.org>, Borrowed utils-linux's
  36  *              mount to add loop support.
  37  */
  38
  39 #include "internal.h"
  40 #include <stdlib.h>
  41 #include <unistd.h>
  42 #include <errno.h>
  43 #include <string.h>
  44 #include <stdio.h>
  45 #include <mntent.h>
  46 #include <sys/mount.h>
  47 #include <ctype.h>
  48 #include <fstab.h>
  49
  50 #if defined BB_FEATURE_MOUNT_LOOP
  51 #include <fcntl.h>
  52 #include <sys/ioctl.h>
  53 #include <linux/loop.h>
  54
  55
  56 static int use_loop = FALSE;
  57 #endif
  58
  59 extern const char mtab_file[];  /* Defined in utility.c */
  60
  61 static const char mount_usage[] = "\tmount [flags]\n"
  62         "\tmount [flags] device directory [-o options,more-options]\n"
  63         "\n" "Flags:\n" "\t-a:\tMount all file systems in fstab.\n"
  64 #ifdef BB_MTAB
  65         "\t-f:\t\"Fake\" mount. Add entry to mount table but don't mount it.\n"
  66         "\t-n:\tDon't write a mount table entry.\n"
  67 #endif
  68         "\t-o option:\tOne of many filesystem options, listed below.\n"
  69         "\t-r:\tMount the filesystem read-only.\n"
  70         "\t-t filesystem-type:\tSpecify the filesystem type.\n"
  71         "\t-w:\tMount for reading and writing (default).\n"
  72         "\n"
  73         "Options for use with the \"-o\" flag:\n"
  74         "\tasync / sync:\tWrites are asynchronous / synchronous.\n"
  75         "\tdev / nodev:\tAllow use of special device files / disallow them.\n"
  76         "\texec / noexec:\tAllow use of executable files / disallow them.\n"
  77 #if defined BB_FEATURE_MOUNT_LOOP
  78         "\tloop: Mounts a file via loop device.\n"
  79 #endif
  80         "\tsuid / nosuid:\tAllow set-user-id-root programs / disallow them.\n"
  81         "\tremount: Re-mount a currently-mounted filesystem, changing its flags.\n"
  82         "\tro / rw: Mount for read-only / read-write.\n"
  83         "\t"
  84
  85         "There are EVEN MORE flags that are specific to each filesystem.\n"
  86         "You'll have to see the written documentation for those.\n";
  87
  88
  89 struct mount_options {
  90         const char *name;
  91         unsigned long and;
  92         unsigned long or;
  93 };
  94
  95 static const struct mount_options mount_options[] = {
  96         {"async", ~MS_SYNCHRONOUS, 0},
  97         {"defaults", ~0, 0},
  98         {"dev", ~MS_NODEV, 0},
  99         {"exec", ~MS_NOEXEC, 0},
 100         {"nodev", ~0, MS_NODEV},
 101         {"noexec", ~0, MS_NOEXEC},
 102         {"nosuid", ~0, MS_NOSUID},
 103         {"remount", ~0, MS_REMOUNT},
 104         {"ro", ~0, MS_RDONLY},
 105         {"rw", ~MS_RDONLY, 0},
 106         {"suid", ~MS_NOSUID, 0},
 107         {"sync", ~0, MS_SYNCHRONOUS},
 108         {0, 0, 0}
 109 };
 110
 111 static int
 112 do_mount(char *specialfile, char *dir, char *filesystemtype,
 113                  long flags, void *string_flags, int useMtab, int fakeIt,
 114                  char *mtab_opts)
 115 {
 116         int status = 0;
 117         char *lofile = NULL;
 118
 119 #if defined BB_MTAB
 120         if (fakeIt == FALSE)
 121 #endif
 122         {
 123 #if defined BB_FEATURE_MOUNT_LOOP
 124                 if (use_loop==TRUE) {
 125                         int loro = flags & MS_RDONLY;
 126                         char *lofile = specialfile;
 127
 128                         specialfile = find_unused_loop_device();
 129                         if (specialfile == NULL) {
 130                                 fprintf(stderr, "Could not find a spare loop device\n");
 131                                 return (FALSE);
 132                         }
 133                         if (set_loop(specialfile, lofile, 0, &loro)) {
 134                                 fprintf(stderr, "Could not setup loop device\n");
 135                                 return (FALSE);
 136                         }
 137                         if (!(flags & MS_RDONLY) && loro) {     /* loop is ro, but wanted rw */
 138                                 fprintf(stderr, "WARNING: loop device is read-only\n");
 139                                 flags &= ~MS_RDONLY;
 140                         }
 141                         use_loop = FALSE;
 142                 }
 143 #endif
 144                 status =
 145                         mount(specialfile, dir, filesystemtype, flags, string_flags);
 146         }
 147
 148
 149         /* If the mount was sucessful, do anything needed, then return TRUE */
 150         if (status == 0) {
 151
 152 #if defined BB_MTAB
 153                 if (useMtab == TRUE) {
 154                         write_mtab(specialfile, dir, filesystemtype, flags, mtab_opts);
 155                 }
 156 #endif
 157                 return (TRUE);
 158         }
 159
 160         /* Bummer.  mount failed.  Clean up */
 161 #if defined BB_FEATURE_MOUNT_LOOP
 162         if (lofile != NULL) {
 163                 del_loop(specialfile);
 164         }
 165 #endif
 166         return (FALSE);
 167 }
 168
 169
 170
 171 /* Seperate standard mount options from the nonstandard string options */
 172 static void
 173 parse_mount_options(char *options, unsigned long *flags, char *strflags)
 174 {
 175         while (options) {
 176                 int gotone = FALSE;
 177                 char *comma = strchr(options, ',');
 178                 const struct mount_options *f = mount_options;
 179
 180                 if (comma)
 181                         *comma = '\0';
 182
 183                 while (f->name != 0) {
 184                         if (strcasecmp(f->name, options) == 0) {
 185
 186                                 *flags &= f->and;
 187                                 *flags |= f->or;
 188                                 gotone = TRUE;
 189                                 break;
 190                         }
 191                         f++;
 192                 }
 193 #if defined BB_FEATURE_MOUNT_LOOP
 194                 if (gotone == FALSE && !strcasecmp("loop", options)) {  /* loop device support */
 195                         use_loop = TRUE;
 196                         gotone = TRUE;
 197                 }
 198 #endif
 199                 if (*strflags && strflags != '\0' && gotone == FALSE) {
 200                         char *temp = strflags;
 201
 202                         temp += strlen(strflags);
 203                         *temp++ = ',';
 204                         *temp++ = '\0';
 205                 }
 206                 if (gotone == FALSE)
 207                         strcat(strflags, options);
 208                 if (comma) {
 209                         *comma = ',';
 210                         options = ++comma;
 211                 } else {
 212                         break;
 213                 }
 214         }
 215 }
 216
 217 int
 218 mount_one(char *blockDevice, char *directory, char *filesystemType,
 219                   unsigned long flags, char *string_flags, int useMtab, int fakeIt,
 220                   char *mtab_opts, int whineOnErrors)
 221 {
 222         int status = 0;
 223
 224         char buf[255];
 225
 226 #if defined BB_FEATURE_USE_PROCFS
 227         if (strcmp(filesystemType, "auto") == 0) {
 228                 FILE *f = fopen("/proc/filesystems", "r");
 229
 230                 if (f == NULL)
 231                         return (FALSE);
 232
 233                 while (fgets(buf, sizeof(buf), f) != NULL) {
 234                         filesystemType = buf;
 235                         if (*filesystemType == '\t') {  // Not a nodev filesystem
 236
 237                                 // Add NULL termination to each line
 238                                 while (*filesystemType && *filesystemType != '\n')
 239                                         filesystemType++;
 240                                 *filesystemType = '\0';
 241
 242                                 filesystemType = buf;
 243                                 filesystemType++;       // hop past tab
 244
 245                                 status = do_mount(blockDevice, directory, filesystemType,
 246                                                                   flags | MS_MGC_VAL, string_flags,
 247                                                                   useMtab, fakeIt, mtab_opts);
 248                                 if (status == TRUE)
 249                                         break;
 250                         }
 251                 }
 252                 fclose(f);
 253         } else
 254 #endif
 255         {
 256                 status = do_mount(blockDevice, directory, filesystemType,
 257                                                   flags | MS_MGC_VAL, string_flags, useMtab,
 258                                                   fakeIt, mtab_opts);
 259         }
 260
 261         if (status == FALSE && whineOnErrors == TRUE) {
 262                 if (whineOnErrors == TRUE) {
 263                         fprintf(stderr, "Mounting %s on %s failed: %s\n",
 264                                         blockDevice, directory, strerror(errno));
 265                 }
 266                 return (FALSE);
 267         }
 268         return (TRUE);
 269 }
 270
 271 extern int mount_main(int argc, char **argv)
 272 {
 273         char string_flags_buf[1024] = "";
 274         char *string_flags = string_flags_buf;
 275         char *extra_opts = string_flags_buf;
 276         unsigned long flags = 0;
 277         char *filesystemType = "auto";
 278         char *device = NULL;
 279         char *directory = NULL;
 280         int all = FALSE;
 281         int fakeIt = FALSE;
 282         int useMtab = TRUE;
 283         int i;
 284
 285         /* Only compiled in if BB_MTAB is not defined */
 286         whine_if_fstab_is_missing();
 287
 288         if (argc == 1) {
 289                 FILE *mountTable = setmntent(mtab_file, "r");
 290
 291                 if (mountTable) {
 292                         struct mntent *m;
 293
 294                         while ((m = getmntent(mountTable)) != 0) {
 295                                 struct fstab *fstabItem;
 296                                 char *blockDevice = m->mnt_fsname;
 297
 298                                 /* Note that if /etc/fstab is missing, libc can't fix up /dev/root for us */
 299                                 if (strcmp(blockDevice, "/dev/root") == 0) {
 300                                         fstabItem = getfsfile("/");
 301                                         if (fstabItem != NULL)
 302                                                 blockDevice = fstabItem->fs_spec;
 303                                 }
 304                                 printf("%s on %s type %s (%s)\n", blockDevice, m->mnt_dir,
 305                                            m->mnt_type, m->mnt_opts);
 306                         }
 307                         endmntent(mountTable);
 308                 } else {
 309                         perror(mtab_file);
 310                 }
 311                 exit(TRUE);
 312         }
 313
 314
 315         /* Parse options */
 316         i = --argc;
 317         argv++;
 318         while (i > 0 && **argv) {
 319                 if (**argv == '-') {
 320                         char *opt = *argv;
 321
 322                         while (i > 0 && *++opt)
 323                                 switch (*opt) {
 324                                 case 'o':
 325                                         if (--i == 0) {
 326                                                 goto goodbye;
 327                                         }
 328                                         parse_mount_options(*(++argv), &flags, string_flags);
 329                                         break;
 330                                 case 'r':
 331                                         flags |= MS_RDONLY;
 332                                         break;
 333                                 case 't':
 334                                         if (--i == 0) {
 335                                                 goto goodbye;
 336                                         }
 337                                         filesystemType = *(++argv);
 338                                         break;
 339                                 case 'w':
 340                                         flags &= ~MS_RDONLY;
 341                                         break;
 342                                 case 'a':
 343                                         all = TRUE;
 344                                         break;
 345 #ifdef BB_MTAB
 346                                 case 'f':
 347                                         fakeIt = TRUE;
 348                                         break;
 349                                 case 'n':
 350                                         useMtab = FALSE;
 351                                         break;
 352 #endif
 353                                 case 'v':
 354                                 case 'h':
 355                                 case '-':
 356                                         goto goodbye;
 357                                 }
 358                 } else {
 359                         if (device == NULL)
 360                                 device = *argv;
 361                         else if (directory == NULL)
 362                                 directory = *argv;
 363                         else {
 364                                 goto goodbye;
 365                         }
 366                 }
 367                 i--;
 368                 argv++;
 369         }
 370
 371         if (all == TRUE) {
 372                 struct mntent *m;
 373                 FILE *f = setmntent("/etc/fstab", "r");
 374
 375                 if (f == NULL) {
 376                         perror("/etc/fstab");
 377                         exit(FALSE);
 378                 }
 379                 while ((m = getmntent(f)) != NULL) {
 380                         // If the file system isn't noauto,
 381                         // and isn't swap or nfs, then mount it
 382                         if ((!strstr(m->mnt_opts, "noauto")) &&
 383                                 (!strstr(m->mnt_type, "swap")) &&
 384                                 (!strstr(m->mnt_type, "nfs"))) {
 385                                 flags = 0;
 386                                 *string_flags = '\0';
 387                                 parse_mount_options(m->mnt_opts, &flags, string_flags);
 388                                 /* If the directory is /, try to remount
 389                                  * with the options specified in fstab */
 390                                 if (m->mnt_dir[0] == '/' && m->mnt_dir[1] == '\0') {
 391                                         flags |= MS_REMOUNT;
 392                                 }
 393                                 if (mount_one(m->mnt_fsname, m->mnt_dir, m->mnt_type,
 394                                                   flags, string_flags, useMtab, fakeIt,
 395                                                   extra_opts, FALSE))
 396                                 {
 397                                         /* Try again, but this time try a remount */
 398                                         mount_one(m->mnt_fsname, m->mnt_dir, m->mnt_type,
 399                                                           flags|MS_REMOUNT, string_flags, useMtab, fakeIt,
 400                                                           extra_opts, TRUE);
 401                                 }
 402                         }
 403                 }
 404                 endmntent(f);
 405         } else {
 406                 if (device && directory) {
 407 #ifdef BB_NFSMOUNT
 408                         if (strcmp(filesystemType, "nfs") == 0) {
 409                                 if (nfsmount
 410                                         (device, directory, &flags, &extra_opts, &string_flags,
 411                                          1) != 0)
 412                                         exit(FALSE);
 413                         }
 414 #endif
 415                         exit(mount_one(device, directory, filesystemType,
 416                                                    flags, string_flags, useMtab, fakeIt,
 417                                                    extra_opts, TRUE));
 418                 } else {
 419                         goto goodbye;
 420                 }
 421         }
 422         exit(TRUE);
 423
 424   goodbye:
 425         usage(mount_usage);
 426 }