LinuxGUI/Ventoy2Disk/Lib/exfat/src/libexfat/mount.c

   1 /*
   2         mount.c (22.10.09)
   3         exFAT file system implementation library.
   4
   5         Free exFAT implementation.
   6         Copyright (C) 2010-2018  Andrew Nayenko
   7
   8         This program is free software; you can redistribute it and/or modify
   9         it under the terms of the GNU General Public License as published by
  10         the Free Software Foundation, either version 2 of the License, or
  11         (at your option) any later version.
  12
  13         This program is distributed in the hope that it will be useful,
  14         but WITHOUT ANY WARRANTY; without even the implied warranty of
  15         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16         GNU General Public License for more details.
  17
  18         You should have received a copy of the GNU General Public License along
  19         with this program; if not, write to the Free Software Foundation, Inc.,
  20         51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21 */
  22
  23 #include "exfat.h"
  24 #include <string.h>
  25 #include <stdlib.h>
  26 #include <errno.h>
  27 #include <inttypes.h>
  28 #include <unistd.h>
  29 #include <sys/types.h>
  30
  31 static uint64_t rootdir_size(const struct exfat* ef)
  32 {
  33         uint32_t clusters = 0;
  34         uint32_t clusters_max = le32_to_cpu(ef->sb->cluster_count);
  35         cluster_t rootdir_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
  36
  37         /* Iterate all clusters of the root directory to calculate its size.
  38            It can't be contiguous because there is no flag to indicate this. */
  39         do
  40         {
  41                 if (clusters == clusters_max) /* infinite loop detected */
  42                 {
  43                         exfat_error("root directory cannot occupy all %d clusters",
  44                                         clusters);
  45                         return 0;
  46                 }
  47                 if (CLUSTER_INVALID(*ef->sb, rootdir_cluster))
  48                 {
  49                         exfat_error("bad cluster %#x while reading root directory",
  50                                         rootdir_cluster);
  51                         return 0;
  52                 }
  53                 rootdir_cluster = exfat_next_cluster(ef, ef->root, rootdir_cluster);
  54                 clusters++;
  55         }
  56         while (rootdir_cluster != EXFAT_CLUSTER_END);
  57
  58         return (uint64_t) clusters * CLUSTER_SIZE(*ef->sb);
  59 }
  60
  61 static const char* get_option(const char* options, const char* option_name)
  62 {
  63         const char* p;
  64         size_t length = strlen(option_name);
  65
  66         for (p = strstr(options, option_name); p; p = strstr(p + 1, option_name))
  67                 if ((p == options || p[-1] == ',') && p[length] == '=')
  68                         return p + length + 1;
  69         return NULL;
  70 }
  71
  72 static int get_int_option(const char* options, const char* option_name,
  73                 int base, int default_value)
  74 {
  75         const char* p = get_option(options, option_name);
  76
  77         if (p == NULL)
  78                 return default_value;
  79         return strtol(p, NULL, base);
  80 }
  81
  82 static bool match_option(const char* options, const char* option_name)
  83 {
  84         const char* p;
  85         size_t length = strlen(option_name);
  86
  87         for (p = strstr(options, option_name); p; p = strstr(p + 1, option_name))
  88                 if ((p == options || p[-1] == ',') &&
  89                                 (p[length] == ',' || p[length] == '\0'))
  90                         return true;
  91         return false;
  92 }
  93
  94 static void parse_options(struct exfat* ef, const char* options)
  95 {
  96         int opt_umask;
  97
  98         opt_umask = get_int_option(options, "umask", 8, 0);
  99         ef->dmask = get_int_option(options, "dmask", 8, opt_umask);
 100         ef->fmask = get_int_option(options, "fmask", 8, opt_umask);
 101
 102         ef->uid = get_int_option(options, "uid", 10, geteuid());
 103         ef->gid = get_int_option(options, "gid", 10, getegid());
 104
 105         ef->noatime = match_option(options, "noatime");
 106
 107         switch (get_int_option(options, "repair", 10, 0))
 108         {
 109         case 1:
 110                 ef->repair = EXFAT_REPAIR_ASK;
 111                 break;
 112         case 2:
 113                 ef->repair = EXFAT_REPAIR_YES;
 114                 break;
 115         default:
 116                 ef->repair = EXFAT_REPAIR_NO;
 117                 break;
 118         }
 119 }
 120
 121 static bool verify_vbr_checksum(const struct exfat* ef, void* sector)
 122 {
 123         off_t sector_size = SECTOR_SIZE(*ef->sb);
 124         uint32_t vbr_checksum;
 125         int i;
 126
 127         if (exfat_pread(ef->dev, sector, sector_size, 0) < 0)
 128         {
 129                 exfat_error("failed to read boot sector");
 130                 return false;
 131         }
 132         vbr_checksum = exfat_vbr_start_checksum(sector, sector_size);
 133         for (i = 1; i < 11; i++)
 134         {
 135                 if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
 136                 {
 137                         exfat_error("failed to read VBR sector");
 138                         return false;
 139                 }
 140                 vbr_checksum = exfat_vbr_add_checksum(sector, sector_size,
 141                                 vbr_checksum);
 142         }
 143         if (exfat_pread(ef->dev, sector, sector_size, i * sector_size) < 0)
 144         {
 145                 exfat_error("failed to read VBR checksum sector");
 146                 return false;
 147         }
 148         for (i = 0; i < sector_size / sizeof(vbr_checksum); i++)
 149                 if (le32_to_cpu(((const le32_t*) sector)[i]) != vbr_checksum)
 150                 {
 151                         exfat_error("invalid VBR checksum 0x%x (expected 0x%x)",
 152                                         le32_to_cpu(((const le32_t*) sector)[i]), vbr_checksum);
 153                         if (!EXFAT_REPAIR(invalid_vbr_checksum, ef, sector, vbr_checksum))
 154                                 return false;
 155                 }
 156         return true;
 157 }
 158
 159 static int commit_super_block(const struct exfat* ef)
 160 {
 161         if (exfat_pwrite(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
 162         {
 163                 exfat_error("failed to write super block");
 164                 return 1;
 165         }
 166         return exfat_fsync(ef->dev);
 167 }
 168
 169 static int prepare_super_block(const struct exfat* ef)
 170 {
 171         if (le16_to_cpu(ef->sb->volume_state) & EXFAT_STATE_MOUNTED)
 172                 exfat_warn("volume was not unmounted cleanly");
 173
 174         if (ef->ro)
 175                 return 0;
 176
 177         ef->sb->volume_state = cpu_to_le16(
 178                         le16_to_cpu(ef->sb->volume_state) | EXFAT_STATE_MOUNTED);
 179         return commit_super_block(ef);
 180 }
 181
 182 static void exfat_free(struct exfat* ef)
 183 {
 184         exfat_close(ef->dev);   /* first of all, close the descriptor */
 185         ef->dev = NULL;                 /* struct exfat_dev is freed by exfat_close() */
 186         free(ef->root);
 187         ef->root = NULL;
 188         free(ef->zero_cluster);
 189         ef->zero_cluster = NULL;
 190         free(ef->cmap.chunk);
 191         ef->cmap.chunk = NULL;
 192         free(ef->upcase);
 193         ef->upcase = NULL;
 194         free(ef->sb);
 195         ef->sb = NULL;
 196 }
 197
 198 int exfat_mount(struct exfat* ef, const char* spec, const char* options)
 199 {
 200         int rc;
 201         enum exfat_mode mode;
 202
 203         exfat_tzset();
 204         memset(ef, 0, sizeof(struct exfat));
 205
 206         parse_options(ef, options);
 207
 208         if (match_option(options, "ro"))
 209                 mode = EXFAT_MODE_RO;
 210         else if (match_option(options, "ro_fallback"))
 211                 mode = EXFAT_MODE_ANY;
 212         else
 213                 mode = EXFAT_MODE_RW;
 214         ef->dev = exfat_open(spec, mode);
 215         if (ef->dev == NULL)
 216                 return -EIO;
 217         if (exfat_get_mode(ef->dev) == EXFAT_MODE_RO)
 218         {
 219                 if (mode == EXFAT_MODE_ANY)
 220                         ef->ro = -1;
 221                 else
 222                         ef->ro = 1;
 223         }
 224
 225         ef->sb = malloc(sizeof(struct exfat_super_block));
 226         if (ef->sb == NULL)
 227         {
 228                 exfat_error("failed to allocate memory for the super block");
 229                 exfat_free(ef);
 230                 return -ENOMEM;
 231         }
 232         memset(ef->sb, 0, sizeof(struct exfat_super_block));
 233
 234         if (exfat_pread(ef->dev, ef->sb, sizeof(struct exfat_super_block), 0) < 0)
 235         {
 236                 exfat_error("failed to read boot sector");
 237                 exfat_free(ef);
 238                 return -EIO;
 239         }
 240         if (memcmp(ef->sb->oem_name, "EXFAT   ", 8) != 0)
 241         {
 242                 exfat_error("exFAT file system is not found");
 243                 exfat_free(ef);
 244                 return -EIO;
 245         }
 246         /* sector cannot be smaller than 512 bytes */
 247         if (ef->sb->sector_bits < 9)
 248         {
 249                 exfat_error("too small sector size: 2^%hhd", ef->sb->sector_bits);
 250                 exfat_free(ef);
 251                 return -EIO;
 252         }
 253         /* officially exFAT supports cluster size up to 32 MB */
 254         if ((int) ef->sb->sector_bits + (int) ef->sb->spc_bits > 25)
 255         {
 256                 exfat_error("too big cluster size: 2^(%hhd+%hhd)",
 257                                 ef->sb->sector_bits, ef->sb->spc_bits);
 258                 exfat_free(ef);
 259                 return -EIO;
 260         }
 261         ef->zero_cluster = malloc(CLUSTER_SIZE(*ef->sb));
 262         if (ef->zero_cluster == NULL)
 263         {
 264                 exfat_error("failed to allocate zero sector");
 265                 exfat_free(ef);
 266                 return -ENOMEM;
 267         }
 268         /* use zero_cluster as a temporary buffer for VBR checksum verification */
 269         if (!verify_vbr_checksum(ef, ef->zero_cluster))
 270         {
 271                 exfat_free(ef);
 272                 return -EIO;
 273         }
 274         memset(ef->zero_cluster, 0, CLUSTER_SIZE(*ef->sb));
 275         if (ef->sb->version.major != 1 || ef->sb->version.minor != 0)
 276         {
 277                 exfat_error("unsupported exFAT version: %hhu.%hhu",
 278                                 ef->sb->version.major, ef->sb->version.minor);
 279                 exfat_free(ef);
 280                 return -EIO;
 281         }
 282         if (ef->sb->fat_count != 1)
 283         {
 284                 exfat_error("unsupported FAT count: %hhu", ef->sb->fat_count);
 285                 exfat_free(ef);
 286                 return -EIO;
 287         }
 288         if (le64_to_cpu(ef->sb->sector_count) * SECTOR_SIZE(*ef->sb) >
 289                         exfat_get_size(ef->dev))
 290         {
 291                 /* this can cause I/O errors later but we don't fail mounting to let
 292                    user rescue data */
 293                 exfat_warn("file system in sectors is larger than device: "
 294                                 "%"PRIu64" * %d > %"PRIu64,
 295                                 le64_to_cpu(ef->sb->sector_count), SECTOR_SIZE(*ef->sb),
 296                                 exfat_get_size(ef->dev));
 297         }
 298         if ((off_t) le32_to_cpu(ef->sb->cluster_count) * CLUSTER_SIZE(*ef->sb) >
 299                         exfat_get_size(ef->dev))
 300         {
 301                 exfat_error("file system in clusters is larger than device: "
 302                                 "%u * %d > %"PRIu64,
 303                                 le32_to_cpu(ef->sb->cluster_count), CLUSTER_SIZE(*ef->sb),
 304                                 exfat_get_size(ef->dev));
 305                 exfat_free(ef);
 306                 return -EIO;
 307         }
 308
 309         ef->root = malloc(sizeof(struct exfat_node));
 310         if (ef->root == NULL)
 311         {
 312                 exfat_error("failed to allocate root node");
 313                 exfat_free(ef);
 314                 return -ENOMEM;
 315         }
 316         memset(ef->root, 0, sizeof(struct exfat_node));
 317         ef->root->attrib = EXFAT_ATTRIB_DIR;
 318         ef->root->start_cluster = le32_to_cpu(ef->sb->rootdir_cluster);
 319         ef->root->fptr_cluster = ef->root->start_cluster;
 320         ef->root->name[0] = cpu_to_le16('\0');
 321         ef->root->size = rootdir_size(ef);
 322         if (ef->root->size == 0)
 323         {
 324                 exfat_free(ef);
 325                 return -EIO;
 326         }
 327         /* exFAT does not have time attributes for the root directory */
 328         ef->root->mtime = 0;
 329         ef->root->atime = 0;
 330         /* always keep at least 1 reference to the root node */
 331         exfat_get_node(ef->root);
 332
 333         rc = exfat_cache_directory(ef, ef->root);
 334         if (rc != 0)
 335                 goto error;
 336         if (ef->upcase == NULL)
 337         {
 338                 exfat_error("upcase table is not found");
 339                 goto error;
 340         }
 341         if (ef->cmap.chunk == NULL)
 342         {
 343                 exfat_error("clusters bitmap is not found");
 344                 goto error;
 345         }
 346
 347         if (prepare_super_block(ef) != 0)
 348                 goto error;
 349
 350         return 0;
 351
 352 error:
 353         exfat_put_node(ef, ef->root);
 354         exfat_reset_cache(ef);
 355         exfat_free(ef);
 356         return -EIO;
 357 }
 358
 359 static void finalize_super_block(struct exfat* ef)
 360 {
 361         if (ef->ro)
 362                 return;
 363
 364         ef->sb->volume_state = cpu_to_le16(
 365                         le16_to_cpu(ef->sb->volume_state) & ~EXFAT_STATE_MOUNTED);
 366
 367         /* Some implementations set the percentage of allocated space to 0xff
 368            on FS creation and never update it. In this case leave it as is. */
 369         if (ef->sb->allocated_percent != 0xff)
 370         {
 371                 uint32_t free, total;
 372
 373                 free = exfat_count_free_clusters(ef);
 374                 total = le32_to_cpu(ef->sb->cluster_count);
 375                 ef->sb->allocated_percent = ((total - free) * 100 + total / 2) / total;
 376         }
 377
 378         commit_super_block(ef); /* ignore return code */
 379 }
 380
 381 void exfat_unmount(struct exfat* ef)
 382 {
 383         exfat_flush_nodes(ef);  /* ignore return code */
 384         exfat_flush(ef);                /* ignore return code */
 385         exfat_put_node(ef, ef->root);
 386         exfat_reset_cache(ef);
 387         finalize_super_block(ef);
 388         exfat_free(ef);                 /* will close the descriptor */
 389 }