libexfat/node.c

   1 /*
   2         node.c (09.10.09)
   3         exFAT file system implementation library.
   4
   5         Free exFAT implementation.
   6         Copyright (C) 2010-2016  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 <errno.h>
  25 #include <string.h>
  26 #include <inttypes.h>
  27
  28 /* on-disk nodes iterator */
  29 struct iterator
  30 {
  31         cluster_t cluster;
  32         off_t offset;
  33         char* chunk;
  34 };
  35
  36 struct exfat_node* exfat_get_node(struct exfat_node* node)
  37 {
  38         /* if we switch to multi-threaded mode we will need atomic
  39            increment here and atomic decrement in exfat_put_node() */
  40         node->references++;
  41         return node;
  42 }
  43
  44 void exfat_put_node(struct exfat* ef, struct exfat_node* node)
  45 {
  46         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
  47
  48         --node->references;
  49         if (node->references < 0)
  50         {
  51                 exfat_get_name(node, buffer);
  52                 exfat_bug("reference counter of '%s' is below zero", buffer);
  53         }
  54         else if (node->references == 0 && node != ef->root)
  55         {
  56                 if (node->is_dirty)
  57                 {
  58                         exfat_get_name(node, buffer);
  59                         exfat_warn("dirty node '%s' with zero references", buffer);
  60                 }
  61         }
  62 }
  63
  64 /**
  65  * This function must be called on rmdir and unlink (after the last
  66  * exfat_put_node()) to free clusters.
  67  */
  68 int exfat_cleanup_node(struct exfat* ef, struct exfat_node* node)
  69 {
  70         int rc = 0;
  71
  72         if (node->references != 0)
  73                 exfat_bug("unable to cleanup a node with %d references",
  74                                 node->references);
  75
  76         if (node->is_unlinked)
  77         {
  78                 /* free all clusters and node structure itself */
  79                 rc = exfat_truncate(ef, node, 0, true);
  80                 /* free the node even in case of error or its memory will be lost */
  81                 free(node);
  82         }
  83         return rc;
  84 }
  85
  86 /**
  87  * Cluster + offset from the beginning of the directory to absolute offset.
  88  */
  89 static off_t co2o(struct exfat* ef, cluster_t cluster, off_t offset)
  90 {
  91         return exfat_c2o(ef, cluster) + offset % CLUSTER_SIZE(*ef->sb);
  92 }
  93
  94 static int opendir(struct exfat* ef, const struct exfat_node* dir,
  95                 struct iterator* it)
  96 {
  97         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
  98
  99         if (!(dir->flags & EXFAT_ATTRIB_DIR))
 100         {
 101                 exfat_get_name(dir, buffer);
 102                 exfat_bug("'%s' is not a directory", buffer);
 103         }
 104         if (CLUSTER_INVALID(dir->start_cluster))
 105         {
 106                 exfat_get_name(dir, buffer);
 107                 exfat_error("'%s' directory starts with invalid cluster %#x", buffer,
 108                                 dir->start_cluster);
 109                 return -EIO;
 110         }
 111         it->cluster = dir->start_cluster;
 112         it->offset = 0;
 113         it->chunk = malloc(CLUSTER_SIZE(*ef->sb));
 114         if (it->chunk == NULL)
 115         {
 116                 exfat_error("failed to allocate memory for directory cluster");
 117                 return -ENOMEM;
 118         }
 119         if (exfat_pread(ef->dev, it->chunk, CLUSTER_SIZE(*ef->sb),
 120                         exfat_c2o(ef, it->cluster)) < 0)
 121         {
 122                 free(it->chunk);
 123                 exfat_get_name(dir, buffer);
 124                 exfat_error("failed to read '%s' directory cluster %#x", buffer,
 125                                 it->cluster);
 126                 return -EIO;
 127         }
 128         return 0;
 129 }
 130
 131 static void closedir(struct iterator* it)
 132 {
 133         it->cluster = 0;
 134         it->offset = 0;
 135         free(it->chunk);
 136         it->chunk = NULL;
 137 }
 138
 139 static bool fetch_next_entry(struct exfat* ef, const struct exfat_node* parent,
 140                 struct iterator* it)
 141 {
 142         /* move iterator to the next entry in the directory */
 143         it->offset += sizeof(struct exfat_entry);
 144         /* fetch the next cluster if needed */
 145         if ((it->offset & (CLUSTER_SIZE(*ef->sb) - 1)) == 0)
 146         {
 147                 /* reached the end of directory; the caller should check this
 148                    condition too */
 149                 if (it->offset >= parent->size)
 150                         return true;
 151                 it->cluster = exfat_next_cluster(ef, parent, it->cluster);
 152                 if (CLUSTER_INVALID(it->cluster))
 153                 {
 154                         exfat_error("invalid cluster 0x%x while reading directory",
 155                                         it->cluster);
 156                         return false;
 157                 }
 158                 if (exfat_pread(ef->dev, it->chunk, CLUSTER_SIZE(*ef->sb),
 159                                 exfat_c2o(ef, it->cluster)) < 0)
 160                 {
 161                         exfat_error("failed to read the next directory cluster %#x",
 162                                         it->cluster);
 163                         return false;
 164                 }
 165         }
 166         return true;
 167 }
 168
 169 static struct exfat_node* allocate_node(void)
 170 {
 171         struct exfat_node* node = malloc(sizeof(struct exfat_node));
 172         if (node == NULL)
 173         {
 174                 exfat_error("failed to allocate node");
 175                 return NULL;
 176         }
 177         memset(node, 0, sizeof(struct exfat_node));
 178         return node;
 179 }
 180
 181 static void init_node_meta1(struct exfat_node* node,
 182                 const struct exfat_entry_meta1* meta1)
 183 {
 184         node->flags = le16_to_cpu(meta1->attrib);
 185         node->mtime = exfat_exfat2unix(meta1->mdate, meta1->mtime,
 186                         meta1->mtime_cs);
 187         /* there is no centiseconds field for atime */
 188         node->atime = exfat_exfat2unix(meta1->adate, meta1->atime, 0);
 189 }
 190
 191 static void init_node_meta2(struct exfat_node* node,
 192                 const struct exfat_entry_meta2* meta2)
 193 {
 194         node->size = le64_to_cpu(meta2->size);
 195         node->start_cluster = le32_to_cpu(meta2->start_cluster);
 196         node->fptr_cluster = node->start_cluster;
 197         node->is_contiguous = ((meta2->flags & EXFAT_FLAG_CONTIGUOUS) != 0);
 198 }
 199
 200 static const struct exfat_entry* get_entry_ptr(const struct exfat* ef,
 201                 const struct iterator* it)
 202 {
 203         return (const struct exfat_entry*)
 204                         (it->chunk + it->offset % CLUSTER_SIZE(*ef->sb));
 205 }
 206
 207 static bool check_node(const struct exfat_node* node, uint16_t actual_checksum,
 208                 uint16_t reference_checksum, uint64_t valid_size, int cluster_size)
 209 {
 210         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
 211         bool ret = true;
 212
 213         /*
 214            Validate checksum first. If it's invalid all other fields probably
 215            contain just garbage.
 216         */
 217         if (actual_checksum != reference_checksum)
 218         {
 219                 exfat_get_name(node, buffer);
 220                 exfat_error("'%s' has invalid checksum (%#hx != %#hx)", buffer,
 221                                 actual_checksum, reference_checksum);
 222                 ret = false;
 223         }
 224
 225         /*
 226            exFAT does not support sparse files but allows files with uninitialized
 227            clusters. For such files valid_size means initialized data size and
 228            cannot be greater than file size. See SetFileValidData() function
 229            description in MSDN.
 230         */
 231         if (valid_size > node->size)
 232         {
 233                 exfat_get_name(node, buffer);
 234                 exfat_error("'%s' has valid size (%"PRIu64") greater than size "
 235                                 "(%"PRIu64")", buffer, valid_size, node->size);
 236                 ret = false;
 237         }
 238
 239         /*
 240            Empty file must have zero start cluster. Non-empty file must start
 241            with a valid cluster. Directories cannot be empty (i.e. must always
 242            have a valid start cluster), but we will check this later in opendir()
 243            to give user a chance to read current directory.
 244         */
 245         if (node->size == 0 && node->start_cluster != EXFAT_CLUSTER_FREE)
 246         {
 247                 exfat_get_name(node, buffer);
 248                 exfat_error("'%s' is empty but start cluster is %#x", buffer,
 249                                 node->start_cluster);
 250                 ret = false;
 251         }
 252         if (node->size > 0 && CLUSTER_INVALID(node->start_cluster))
 253         {
 254                 exfat_get_name(node, buffer);
 255                 exfat_error("'%s' points to invalid cluster %#x", buffer,
 256                                 node->start_cluster);
 257                 ret = false;
 258         }
 259
 260         /* Empty file or directory must be marked as non-contiguous. */
 261         if (node->size == 0 && node->is_contiguous)
 262         {
 263                 exfat_get_name(node, buffer);
 264                 exfat_error("'%s' is empty but marked as contiguous (%#x)", buffer,
 265                                 node->flags);
 266                 ret = false;
 267         }
 268
 269         /* Directory size must be aligned on at cluster boundary. */
 270         if ((node->flags & EXFAT_ATTRIB_DIR) && node->size % cluster_size != 0)
 271         {
 272                 exfat_get_name(node, buffer);
 273                 exfat_error("'%s' directory size %"PRIu64" is not divisible by %d", buffer,
 274                                 node->size, cluster_size);
 275                 ret = false;
 276         }
 277
 278         return ret;
 279 }
 280
 281 static void decompress_upcase(uint16_t* output, const le16_t* source,
 282                 size_t size)
 283 {
 284         size_t si;
 285         size_t oi;
 286
 287         for (oi = 0; oi < EXFAT_UPCASE_CHARS; oi++)
 288                 output[oi] = oi;
 289
 290         for (si = 0, oi = 0; si < size && oi < EXFAT_UPCASE_CHARS; si++)
 291         {
 292                 uint16_t ch = le16_to_cpu(source[si]);
 293
 294                 if (ch == 0xffff && si + 1 < size)      /* indicates a run */
 295                         oi += le16_to_cpu(source[++si]);
 296                 else
 297                         output[oi++] = ch;
 298         }
 299 }
 300
 301 /*
 302  * Reads one entry in directory at position pointed by iterator and fills
 303  * node structure.
 304  */
 305 static int readdir(struct exfat* ef, const struct exfat_node* parent,
 306                 struct exfat_node** node, struct iterator* it)
 307 {
 308         int rc = -EIO;
 309         const struct exfat_entry* entry;
 310         const struct exfat_entry_meta1* meta1;
 311         const struct exfat_entry_meta2* meta2;
 312         const struct exfat_entry_name* file_name;
 313         const struct exfat_entry_upcase* upcase;
 314         const struct exfat_entry_bitmap* bitmap;
 315         const struct exfat_entry_label* label;
 316         uint8_t continuations = 0;
 317         le16_t* namep = NULL;
 318         uint16_t reference_checksum = 0;
 319         uint16_t actual_checksum = 0;
 320         uint64_t valid_size = 0;
 321         uint64_t upcase_size = 0;
 322         le16_t* upcase_comp = NULL;
 323
 324         *node = NULL;
 325
 326         for (;;)
 327         {
 328                 if (it->offset >= parent->size)
 329                 {
 330                         if (continuations != 0)
 331                         {
 332                                 exfat_error("expected %hhu continuations", continuations);
 333                                 goto error;
 334                         }
 335                         return -ENOENT; /* that's OK, means end of directory */
 336                 }
 337
 338                 entry = get_entry_ptr(ef, it);
 339                 switch (entry->type)
 340                 {
 341                 case EXFAT_ENTRY_FILE:
 342                         if (continuations != 0)
 343                         {
 344                                 exfat_error("expected %hhu continuations before new entry",
 345                                                 continuations);
 346                                 goto error;
 347                         }
 348                         meta1 = (const struct exfat_entry_meta1*) entry;
 349                         continuations = meta1->continuations;
 350                         /* each file entry must have at least 2 continuations:
 351                            info and name */
 352                         if (continuations < 2)
 353                         {
 354                                 exfat_error("too few continuations (%hhu)", continuations);
 355                                 goto error;
 356                         }
 357                         if (continuations > 1 +
 358                                         DIV_ROUND_UP(EXFAT_NAME_MAX, EXFAT_ENAME_MAX))
 359                         {
 360                                 exfat_error("too many continuations (%hhu)", continuations);
 361                                 goto error;
 362                         }
 363                         reference_checksum = le16_to_cpu(meta1->checksum);
 364                         actual_checksum = exfat_start_checksum(meta1);
 365                         *node = allocate_node();
 366                         if (*node == NULL)
 367                         {
 368                                 rc = -ENOMEM;
 369                                 goto error;
 370                         }
 371                         /* new node has zero reference counter */
 372                         (*node)->entry_cluster = it->cluster;
 373                         (*node)->entry_offset = it->offset;
 374                         init_node_meta1(*node, meta1);
 375                         namep = (*node)->name;
 376                         break;
 377
 378                 case EXFAT_ENTRY_FILE_INFO:
 379                         if (continuations < 2)
 380                         {
 381                                 exfat_error("unexpected continuation (%hhu)",
 382                                                 continuations);
 383                                 goto error;
 384                         }
 385                         meta2 = (const struct exfat_entry_meta2*) entry;
 386                         if (meta2->flags & ~(EXFAT_FLAG_ALWAYS1 | EXFAT_FLAG_CONTIGUOUS))
 387                         {
 388                                 exfat_error("unknown flags in meta2 (0x%hhx)", meta2->flags);
 389                                 goto error;
 390                         }
 391                         init_node_meta2(*node, meta2);
 392                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 393                         valid_size = le64_to_cpu(meta2->valid_size);
 394                         --continuations;
 395                         break;
 396
 397                 case EXFAT_ENTRY_FILE_NAME:
 398                         if (continuations == 0)
 399                         {
 400                                 exfat_error("unexpected continuation");
 401                                 goto error;
 402                         }
 403                         file_name = (const struct exfat_entry_name*) entry;
 404                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 405
 406                         memcpy(namep, file_name->name,
 407                                         MIN(EXFAT_ENAME_MAX,
 408                                                 ((*node)->name + EXFAT_NAME_MAX - namep)) *
 409                                         sizeof(le16_t));
 410                         namep += EXFAT_ENAME_MAX;
 411                         if (--continuations == 0)
 412                         {
 413                                 if (!check_node(*node, actual_checksum, reference_checksum,
 414                                                 valid_size, CLUSTER_SIZE(*ef->sb)))
 415                                         goto error;
 416                                 if (!fetch_next_entry(ef, parent, it))
 417                                         goto error;
 418                                 return 0; /* entry completed */
 419                         }
 420                         break;
 421
 422                 case EXFAT_ENTRY_UPCASE:
 423                         if (ef->upcase != NULL)
 424                                 break;
 425                         upcase = (const struct exfat_entry_upcase*) entry;
 426                         if (CLUSTER_INVALID(le32_to_cpu(upcase->start_cluster)))
 427                         {
 428                                 exfat_error("invalid cluster 0x%x in upcase table",
 429                                                 le32_to_cpu(upcase->start_cluster));
 430                                 goto error;
 431                         }
 432                         upcase_size = le64_to_cpu(upcase->size);
 433                         if (upcase_size == 0 ||
 434                                 upcase_size > EXFAT_UPCASE_CHARS * sizeof(uint16_t) ||
 435                                 upcase_size % sizeof(uint16_t) != 0)
 436                         {
 437                                 exfat_error("bad upcase table size (%"PRIu64" bytes)",
 438                                                 upcase_size);
 439                                 goto error;
 440                         }
 441                         upcase_comp = malloc(upcase_size);
 442                         if (upcase_comp == NULL)
 443                         {
 444                                 exfat_error("failed to allocate upcase table (%"PRIu64" bytes)",
 445                                                 upcase_size);
 446                                 rc = -ENOMEM;
 447                                 goto error;
 448                         }
 449
 450                         /* read compressed upcase table */
 451                         if (exfat_pread(ef->dev, upcase_comp, upcase_size,
 452                                         exfat_c2o(ef, le32_to_cpu(upcase->start_cluster))) < 0)
 453                         {
 454                                 free(upcase_comp);
 455                                 exfat_error("failed to read upper case table "
 456                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 457                                                 upcase_size,
 458                                                 le32_to_cpu(upcase->start_cluster));
 459                                 goto error;
 460                         }
 461
 462                         /* decompress upcase table */
 463                         ef->upcase = calloc(EXFAT_UPCASE_CHARS, sizeof(uint16_t));
 464                         if (ef->upcase == NULL)
 465                         {
 466                                 free(upcase_comp);
 467                                 exfat_error("failed to allocate decompressed upcase table");
 468                                 rc = -ENOMEM;
 469                                 goto error;
 470                         }
 471                         decompress_upcase(ef->upcase, upcase_comp,
 472                                         upcase_size / sizeof(uint16_t));
 473                         free(upcase_comp);
 474                         break;
 475
 476                 case EXFAT_ENTRY_BITMAP:
 477                         bitmap = (const struct exfat_entry_bitmap*) entry;
 478                         ef->cmap.start_cluster = le32_to_cpu(bitmap->start_cluster);
 479                         if (CLUSTER_INVALID(ef->cmap.start_cluster))
 480                         {
 481                                 exfat_error("invalid cluster 0x%x in clusters bitmap",
 482                                                 ef->cmap.start_cluster);
 483                                 goto error;
 484                         }
 485                         ef->cmap.size = le32_to_cpu(ef->sb->cluster_count) -
 486                                 EXFAT_FIRST_DATA_CLUSTER;
 487                         if (le64_to_cpu(bitmap->size) < DIV_ROUND_UP(ef->cmap.size, 8))
 488                         {
 489                                 exfat_error("invalid clusters bitmap size: %"PRIu64
 490                                                 " (expected at least %u)",
 491                                                 le64_to_cpu(bitmap->size),
 492                                                 DIV_ROUND_UP(ef->cmap.size, 8));
 493                                 goto error;
 494                         }
 495                         /* FIXME bitmap can be rather big, up to 512 MB */
 496                         ef->cmap.chunk_size = ef->cmap.size;
 497                         ef->cmap.chunk = malloc(BMAP_SIZE(ef->cmap.chunk_size));
 498                         if (ef->cmap.chunk == NULL)
 499                         {
 500                                 exfat_error("failed to allocate clusters bitmap chunk "
 501                                                 "(%"PRIu64" bytes)", le64_to_cpu(bitmap->size));
 502                                 rc = -ENOMEM;
 503                                 goto error;
 504                         }
 505
 506                         if (exfat_pread(ef->dev, ef->cmap.chunk,
 507                                         BMAP_SIZE(ef->cmap.chunk_size),
 508                                         exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
 509                         {
 510                                 exfat_error("failed to read clusters bitmap "
 511                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 512                                                 le64_to_cpu(bitmap->size), ef->cmap.start_cluster);
 513                                 goto error;
 514                         }
 515                         break;
 516
 517                 case EXFAT_ENTRY_LABEL:
 518                         label = (const struct exfat_entry_label*) entry;
 519                         if (label->length > EXFAT_ENAME_MAX)
 520                         {
 521                                 exfat_error("too long label (%hhu chars)", label->length);
 522                                 goto error;
 523                         }
 524                         if (utf16_to_utf8(ef->label, label->name,
 525                                                 sizeof(ef->label), EXFAT_ENAME_MAX) != 0)
 526                                 goto error;
 527                         break;
 528
 529                 default:
 530                         if (!(entry->type & EXFAT_ENTRY_VALID))
 531                                 break; /* deleted entry, ignore it */
 532                         if (!(entry->type & EXFAT_ENTRY_OPTIONAL))
 533                         {
 534                                 exfat_error("unknown entry type %#hhx", entry->type);
 535                                 goto error;
 536                         }
 537                         /* optional entry, warn and skip */
 538                         exfat_warn("unknown entry type %#hhx", entry->type);
 539                         if (continuations == 0)
 540                         {
 541                                 exfat_error("unexpected continuation");
 542                                 goto error;
 543                         }
 544                         --continuations;
 545                         break;
 546                 }
 547
 548                 if (!fetch_next_entry(ef, parent, it))
 549                         goto error;
 550         }
 551         /* we never reach here */
 552
 553 error:
 554         free(*node);
 555         *node = NULL;
 556         return rc;
 557 }
 558
 559 int exfat_cache_directory(struct exfat* ef, struct exfat_node* dir)
 560 {
 561         struct iterator it;
 562         int rc;
 563         struct exfat_node* node;
 564         struct exfat_node* current = NULL;
 565
 566         if (dir->is_cached)
 567                 return 0; /* already cached */
 568
 569         rc = opendir(ef, dir, &it);
 570         if (rc != 0)
 571                 return rc;
 572         while ((rc = readdir(ef, dir, &node, &it)) == 0)
 573         {
 574                 node->parent = dir;
 575                 if (current != NULL)
 576                 {
 577                         current->next = node;
 578                         node->prev = current;
 579                 }
 580                 else
 581                         dir->child = node;
 582
 583                 current = node;
 584         }
 585         closedir(&it);
 586
 587         if (rc != -ENOENT)
 588         {
 589                 /* rollback */
 590                 for (current = dir->child; current; current = node)
 591                 {
 592                         node = current->next;
 593                         free(current);
 594                 }
 595                 dir->child = NULL;
 596                 return rc;
 597         }
 598
 599         dir->is_cached = true;
 600         return 0;
 601 }
 602
 603 static void tree_attach(struct exfat_node* dir, struct exfat_node* node)
 604 {
 605         node->parent = dir;
 606         if (dir->child)
 607         {
 608                 dir->child->prev = node;
 609                 node->next = dir->child;
 610         }
 611         dir->child = node;
 612 }
 613
 614 static void tree_detach(struct exfat_node* node)
 615 {
 616         if (node->prev)
 617                 node->prev->next = node->next;
 618         else /* this is the first node in the list */
 619                 node->parent->child = node->next;
 620         if (node->next)
 621                 node->next->prev = node->prev;
 622         node->parent = NULL;
 623         node->prev = NULL;
 624         node->next = NULL;
 625 }
 626
 627 static void reset_cache(struct exfat* ef, struct exfat_node* node)
 628 {
 629         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
 630
 631         while (node->child)
 632         {
 633                 struct exfat_node* p = node->child;
 634                 reset_cache(ef, p);
 635                 tree_detach(p);
 636                 free(p);
 637         }
 638         node->is_cached = false;
 639         if (node->references != 0)
 640         {
 641                 exfat_get_name(node, buffer);
 642                 exfat_warn("non-zero reference counter (%d) for '%s'",
 643                                 node->references, buffer);
 644         }
 645         if (node != ef->root && node->is_dirty)
 646         {
 647                 exfat_get_name(node, buffer);
 648                 exfat_bug("node '%s' is dirty", buffer);
 649         }
 650         while (node->references)
 651                 exfat_put_node(ef, node);
 652 }
 653
 654 void exfat_reset_cache(struct exfat* ef)
 655 {
 656         reset_cache(ef, ef->root);
 657 }
 658
 659 static bool next_entry(struct exfat* ef, const struct exfat_node* parent,
 660                 cluster_t* cluster, off_t* offset)
 661 {
 662         *offset += sizeof(struct exfat_entry);
 663         if (*offset % CLUSTER_SIZE(*ef->sb) == 0)
 664         {
 665                 *cluster = exfat_next_cluster(ef, parent, *cluster);
 666                 if (CLUSTER_INVALID(*cluster))
 667                 {
 668                         exfat_error("invalid cluster %#x while getting next entry",
 669                                         *cluster);
 670                         return false;
 671                 }
 672         }
 673         return true;
 674 }
 675
 676 int exfat_flush_node(struct exfat* ef, struct exfat_node* node)
 677 {
 678         cluster_t cluster;
 679         off_t offset;
 680         off_t meta1_offset, meta2_offset;
 681         struct exfat_entry_meta1 meta1;
 682         struct exfat_entry_meta2 meta2;
 683
 684         if (!node->is_dirty)
 685                 return 0; /* no need to flush */
 686
 687         if (ef->ro)
 688                 exfat_bug("unable to flush node to read-only FS");
 689
 690         if (node->parent == NULL)
 691                 return 0; /* do not flush unlinked node */
 692
 693         cluster = node->entry_cluster;
 694         offset = node->entry_offset;
 695         meta1_offset = co2o(ef, cluster, offset);
 696         if (!next_entry(ef, node->parent, &cluster, &offset))
 697                 return -EIO;
 698         meta2_offset = co2o(ef, cluster, offset);
 699
 700         if (exfat_pread(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 701         {
 702                 exfat_error("failed to read meta1 entry on flush");
 703                 return -EIO;
 704         }
 705         if (meta1.type != EXFAT_ENTRY_FILE)
 706                 exfat_bug("invalid type of meta1: 0x%hhx", meta1.type);
 707         meta1.attrib = cpu_to_le16(node->flags);
 708         exfat_unix2exfat(node->mtime, &meta1.mdate, &meta1.mtime, &meta1.mtime_cs);
 709         exfat_unix2exfat(node->atime, &meta1.adate, &meta1.atime, NULL);
 710
 711         if (exfat_pread(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 712         {
 713                 exfat_error("failed to read meta2 entry on flush");
 714                 return -EIO;
 715         }
 716         if (meta2.type != EXFAT_ENTRY_FILE_INFO)
 717                 exfat_bug("invalid type of meta2: 0x%hhx", meta2.type);
 718         meta2.size = meta2.valid_size = cpu_to_le64(node->size);
 719         meta2.start_cluster = cpu_to_le32(node->start_cluster);
 720         meta2.flags = EXFAT_FLAG_ALWAYS1;
 721         /* empty files must not be marked as contiguous */
 722         if (node->size != 0 && node->is_contiguous)
 723                 meta2.flags |= EXFAT_FLAG_CONTIGUOUS;
 724         /* name hash remains unchanged, no need to recalculate it */
 725
 726         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 727
 728         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 729         {
 730                 exfat_error("failed to write meta1 entry on flush");
 731                 return -EIO;
 732         }
 733         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 734         {
 735                 exfat_error("failed to write meta2 entry on flush");
 736                 return -EIO;
 737         }
 738
 739         node->is_dirty = false;
 740         return exfat_flush(ef);
 741 }
 742
 743 static bool erase_entry(struct exfat* ef, struct exfat_node* node)
 744 {
 745         cluster_t cluster = node->entry_cluster;
 746         off_t offset = node->entry_offset;
 747         int name_entries = DIV_ROUND_UP(utf16_length(node->name), EXFAT_ENAME_MAX);
 748         uint8_t entry_type;
 749
 750         entry_type = EXFAT_ENTRY_FILE & ~EXFAT_ENTRY_VALID;
 751         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 752         {
 753                 exfat_error("failed to erase meta1 entry");
 754                 return false;
 755         }
 756
 757         if (!next_entry(ef, node->parent, &cluster, &offset))
 758                 return false;
 759         entry_type = EXFAT_ENTRY_FILE_INFO & ~EXFAT_ENTRY_VALID;
 760         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 761         {
 762                 exfat_error("failed to erase meta2 entry");
 763                 return false;
 764         }
 765
 766         while (name_entries--)
 767         {
 768                 if (!next_entry(ef, node->parent, &cluster, &offset))
 769                         return false;
 770                 entry_type = EXFAT_ENTRY_FILE_NAME & ~EXFAT_ENTRY_VALID;
 771                 if (exfat_pwrite(ef->dev, &entry_type, 1,
 772                                 co2o(ef, cluster, offset)) < 0)
 773                 {
 774                         exfat_error("failed to erase name entry");
 775                         return false;
 776                 }
 777         }
 778         return true;
 779 }
 780
 781 static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
 782                 off_t deleted_offset)
 783 {
 784         const struct exfat_node* node;
 785         const struct exfat_node* last_node;
 786         uint64_t entries = 0;
 787         uint64_t new_size;
 788
 789         if (!(dir->flags & EXFAT_ATTRIB_DIR))
 790                 exfat_bug("attempted to shrink a file");
 791         if (!dir->is_cached)
 792                 exfat_bug("attempted to shrink uncached directory");
 793
 794         for (last_node = node = dir->child; node; node = node->next)
 795         {
 796                 if (deleted_offset < node->entry_offset)
 797                 {
 798                         /* there are other entries after the removed one, no way to shrink
 799                            this directory */
 800                         return 0;
 801                 }
 802                 if (last_node->entry_offset < node->entry_offset)
 803                         last_node = node;
 804         }
 805
 806         if (last_node)
 807         {
 808                 /* offset of the last entry */
 809                 entries += last_node->entry_offset / sizeof(struct exfat_entry);
 810                 /* two subentries with meta info */
 811                 entries += 2;
 812                 /* subentries with file name */
 813                 entries += DIV_ROUND_UP(utf16_length(last_node->name),
 814                                 EXFAT_ENAME_MAX);
 815         }
 816
 817         new_size = DIV_ROUND_UP(entries * sizeof(struct exfat_entry),
 818                                  CLUSTER_SIZE(*ef->sb)) * CLUSTER_SIZE(*ef->sb);
 819         if (new_size == 0) /* directory always has at least 1 cluster */
 820                 new_size = CLUSTER_SIZE(*ef->sb);
 821         if (new_size == dir->size)
 822                 return 0;
 823         return exfat_truncate(ef, dir, new_size, true);
 824 }
 825
 826 static int delete(struct exfat* ef, struct exfat_node* node)
 827 {
 828         struct exfat_node* parent = node->parent;
 829         off_t deleted_offset = node->entry_offset;
 830         int rc;
 831
 832         exfat_get_node(parent);
 833         if (!erase_entry(ef, node))
 834         {
 835                 exfat_put_node(ef, parent);
 836                 return -EIO;
 837         }
 838         exfat_update_mtime(parent);
 839         tree_detach(node);
 840         rc = shrink_directory(ef, parent, deleted_offset);
 841         node->is_unlinked = true;
 842         if (rc != 0)
 843         {
 844                 exfat_flush_node(ef, parent);
 845                 exfat_put_node(ef, parent);
 846                 return rc;
 847         }
 848         rc = exfat_flush_node(ef, parent);
 849         exfat_put_node(ef, parent);
 850         return rc;
 851 }
 852
 853 int exfat_unlink(struct exfat* ef, struct exfat_node* node)
 854 {
 855         if (node->flags & EXFAT_ATTRIB_DIR)
 856                 return -EISDIR;
 857         return delete(ef, node);
 858 }
 859
 860 int exfat_rmdir(struct exfat* ef, struct exfat_node* node)
 861 {
 862         int rc;
 863
 864         if (!(node->flags & EXFAT_ATTRIB_DIR))
 865                 return -ENOTDIR;
 866         /* check that directory is empty */
 867         rc = exfat_cache_directory(ef, node);
 868         if (rc != 0)
 869                 return rc;
 870         if (node->child)
 871                 return -ENOTEMPTY;
 872         return delete(ef, node);
 873 }
 874
 875 static int grow_directory(struct exfat* ef, struct exfat_node* dir,
 876                 uint64_t asize, uint32_t difference)
 877 {
 878         return exfat_truncate(ef, dir,
 879                         DIV_ROUND_UP(asize + difference, CLUSTER_SIZE(*ef->sb))
 880                                 * CLUSTER_SIZE(*ef->sb), true);
 881 }
 882
 883 static int find_slot(struct exfat* ef, struct exfat_node* dir,
 884                 cluster_t* cluster, off_t* offset, int subentries)
 885 {
 886         struct iterator it;
 887         int rc;
 888         const struct exfat_entry* entry;
 889         int contiguous = 0;
 890
 891         rc = opendir(ef, dir, &it);
 892         if (rc != 0)
 893                 return rc;
 894         for (;;)
 895         {
 896                 if (contiguous == 0)
 897                 {
 898                         *cluster = it.cluster;
 899                         *offset = it.offset;
 900                 }
 901                 entry = get_entry_ptr(ef, &it);
 902                 if (entry->type & EXFAT_ENTRY_VALID)
 903                         contiguous = 0;
 904                 else
 905                         contiguous++;
 906                 if (contiguous == subentries)
 907                         break;  /* suitable slot is found */
 908                 if (it.offset + sizeof(struct exfat_entry) >= dir->size)
 909                 {
 910                         rc = grow_directory(ef, dir, dir->size,
 911                                         (subentries - contiguous) * sizeof(struct exfat_entry));
 912                         if (rc != 0)
 913                         {
 914                                 closedir(&it);
 915                                 return rc;
 916                         }
 917                 }
 918                 if (!fetch_next_entry(ef, dir, &it))
 919                 {
 920                         closedir(&it);
 921                         return -EIO;
 922                 }
 923         }
 924         closedir(&it);
 925         return 0;
 926 }
 927
 928 static int commit_entry(struct exfat* ef, struct exfat_node* dir,
 929                 const le16_t* name, cluster_t cluster, off_t offset, uint16_t attrib)
 930 {
 931         struct exfat_node* node;
 932         struct exfat_entry_meta1 meta1;
 933         struct exfat_entry_meta2 meta2;
 934         const size_t name_length = utf16_length(name);
 935         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
 936         int i;
 937
 938         node = allocate_node();
 939         if (node == NULL)
 940                 return -ENOMEM;
 941         node->entry_cluster = cluster;
 942         node->entry_offset = offset;
 943         memcpy(node->name, name, name_length * sizeof(le16_t));
 944
 945         memset(&meta1, 0, sizeof(meta1));
 946         meta1.type = EXFAT_ENTRY_FILE;
 947         meta1.continuations = 1 + name_entries;
 948         meta1.attrib = cpu_to_le16(attrib);
 949         exfat_unix2exfat(time(NULL), &meta1.crdate, &meta1.crtime,
 950                         &meta1.crtime_cs);
 951         meta1.adate = meta1.mdate = meta1.crdate;
 952         meta1.atime = meta1.mtime = meta1.crtime;
 953         meta1.mtime_cs = meta1.crtime_cs; /* there is no atime_cs */
 954
 955         memset(&meta2, 0, sizeof(meta2));
 956         meta2.type = EXFAT_ENTRY_FILE_INFO;
 957         meta2.flags = EXFAT_FLAG_ALWAYS1;
 958         meta2.name_length = name_length;
 959         meta2.name_hash = exfat_calc_name_hash(ef, node->name, name_length);
 960         meta2.start_cluster = cpu_to_le32(EXFAT_CLUSTER_FREE);
 961
 962         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 963
 964         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
 965                         co2o(ef, cluster, offset)) < 0)
 966         {
 967                 exfat_error("failed to write meta1 entry");
 968                 return -EIO;
 969         }
 970         if (!next_entry(ef, dir, &cluster, &offset))
 971                 return -EIO;
 972         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
 973                         co2o(ef, cluster, offset)) < 0)
 974         {
 975                 exfat_error("failed to write meta2 entry");
 976                 return -EIO;
 977         }
 978         for (i = 0; i < name_entries; i++)
 979         {
 980                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
 981                 memcpy(name_entry.name, node->name + i * EXFAT_ENAME_MAX,
 982                                 MIN(EXFAT_ENAME_MAX, EXFAT_NAME_MAX - i * EXFAT_ENAME_MAX) *
 983                                 sizeof(le16_t));
 984                 if (!next_entry(ef, dir, &cluster, &offset))
 985                         return -EIO;
 986                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
 987                                 co2o(ef, cluster, offset)) < 0)
 988                 {
 989                         exfat_error("failed to write name entry");
 990                         return -EIO;
 991                 }
 992         }
 993
 994         init_node_meta1(node, &meta1);
 995         init_node_meta2(node, &meta2);
 996
 997         tree_attach(dir, node);
 998         exfat_update_mtime(dir);
 999         return 0;
1000 }
1001
1002 static int create(struct exfat* ef, const char* path, uint16_t attrib)
1003 {
1004         struct exfat_node* dir;
1005         struct exfat_node* existing;
1006         cluster_t cluster = EXFAT_CLUSTER_BAD;
1007         off_t offset = -1;
1008         le16_t name[EXFAT_NAME_MAX + 1];
1009         int rc;
1010
1011         rc = exfat_split(ef, &dir, &existing, name, path);
1012         if (rc != 0)
1013                 return rc;
1014         if (existing != NULL)
1015         {
1016                 exfat_put_node(ef, existing);
1017                 exfat_put_node(ef, dir);
1018                 return -EEXIST;
1019         }
1020
1021         rc = find_slot(ef, dir, &cluster, &offset,
1022                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1023         if (rc != 0)
1024         {
1025                 exfat_put_node(ef, dir);
1026                 return rc;
1027         }
1028         rc = commit_entry(ef, dir, name, cluster, offset, attrib);
1029         if (rc != 0)
1030         {
1031                 exfat_put_node(ef, dir);
1032                 return rc;
1033         }
1034         rc = exfat_flush_node(ef, dir);
1035         exfat_put_node(ef, dir);
1036         return rc;
1037 }
1038
1039 int exfat_mknod(struct exfat* ef, const char* path)
1040 {
1041         return create(ef, path, EXFAT_ATTRIB_ARCH);
1042 }
1043
1044 int exfat_mkdir(struct exfat* ef, const char* path)
1045 {
1046         int rc;
1047         struct exfat_node* node;
1048
1049         rc = create(ef, path, EXFAT_ATTRIB_DIR);
1050         if (rc != 0)
1051                 return rc;
1052         rc = exfat_lookup(ef, &node, path);
1053         if (rc != 0)
1054                 return 0;
1055         /* directories always have at least one cluster */
1056         rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
1057         if (rc != 0)
1058         {
1059                 delete(ef, node);
1060                 exfat_put_node(ef, node);
1061                 return rc;
1062         }
1063         rc = exfat_flush_node(ef, node);
1064         if (rc != 0)
1065         {
1066                 delete(ef, node);
1067                 exfat_put_node(ef, node);
1068                 return rc;
1069         }
1070         exfat_put_node(ef, node);
1071         return 0;
1072 }
1073
1074 static int rename_entry(struct exfat* ef, struct exfat_node* dir,
1075                 struct exfat_node* node, const le16_t* name, cluster_t new_cluster,
1076                 off_t new_offset)
1077 {
1078         struct exfat_entry_meta1 meta1;
1079         struct exfat_entry_meta2 meta2;
1080         cluster_t old_cluster = node->entry_cluster;
1081         off_t old_offset = node->entry_offset;
1082         const size_t name_length = utf16_length(name);
1083         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
1084         int i;
1085
1086         if (exfat_pread(ef->dev, &meta1, sizeof(meta1),
1087                         co2o(ef, old_cluster, old_offset)) < 0)
1088         {
1089                 exfat_error("failed to read meta1 entry on rename");
1090                 return -EIO;
1091         }
1092         if (!next_entry(ef, node->parent, &old_cluster, &old_offset))
1093                 return -EIO;
1094         if (exfat_pread(ef->dev, &meta2, sizeof(meta2),
1095                         co2o(ef, old_cluster, old_offset)) < 0)
1096         {
1097                 exfat_error("failed to read meta2 entry on rename");
1098                 return -EIO;
1099         }
1100         meta1.continuations = 1 + name_entries;
1101         meta2.name_hash = exfat_calc_name_hash(ef, name, name_length);
1102         meta2.name_length = name_length;
1103         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, name);
1104
1105         if (!erase_entry(ef, node))
1106                 return -EIO;
1107
1108         node->entry_cluster = new_cluster;
1109         node->entry_offset = new_offset;
1110
1111         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
1112                         co2o(ef, new_cluster, new_offset)) < 0)
1113         {
1114                 exfat_error("failed to write meta1 entry on rename");
1115                 return -EIO;
1116         }
1117         if (!next_entry(ef, dir, &new_cluster, &new_offset))
1118                 return -EIO;
1119         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
1120                         co2o(ef, new_cluster, new_offset)) < 0)
1121         {
1122                 exfat_error("failed to write meta2 entry on rename");
1123                 return -EIO;
1124         }
1125
1126         for (i = 0; i < name_entries; i++)
1127         {
1128                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
1129                 memcpy(name_entry.name, name + i * EXFAT_ENAME_MAX,
1130                                 EXFAT_ENAME_MAX * sizeof(le16_t));
1131                 if (!next_entry(ef, dir, &new_cluster, &new_offset))
1132                         return -EIO;
1133                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
1134                                 co2o(ef, new_cluster, new_offset)) < 0)
1135                 {
1136                         exfat_error("failed to write name entry on rename");
1137                         return -EIO;
1138                 }
1139         }
1140
1141         memcpy(node->name, name, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
1142         tree_detach(node);
1143         tree_attach(dir, node);
1144         return 0;
1145 }
1146
1147 int exfat_rename(struct exfat* ef, const char* old_path, const char* new_path)
1148 {
1149         struct exfat_node* node;
1150         struct exfat_node* existing;
1151         struct exfat_node* dir;
1152         cluster_t cluster = EXFAT_CLUSTER_BAD;
1153         off_t offset = -1;
1154         le16_t name[EXFAT_NAME_MAX + 1];
1155         int rc;
1156
1157         rc = exfat_lookup(ef, &node, old_path);
1158         if (rc != 0)
1159                 return rc;
1160
1161         rc = exfat_split(ef, &dir, &existing, name, new_path);
1162         if (rc != 0)
1163         {
1164                 exfat_put_node(ef, node);
1165                 return rc;
1166         }
1167
1168         /* check that target is not a subdirectory of the source */
1169         if (node->flags & EXFAT_ATTRIB_DIR)
1170         {
1171                 struct exfat_node* p;
1172
1173                 for (p = dir; p; p = p->parent)
1174                         if (node == p)
1175                         {
1176                                 if (existing != NULL)
1177                                         exfat_put_node(ef, existing);
1178                                 exfat_put_node(ef, dir);
1179                                 exfat_put_node(ef, node);
1180                                 return -EINVAL;
1181                         }
1182         }
1183
1184         if (existing != NULL)
1185         {
1186                 /* remove target if it's not the same node as source */
1187                 if (existing != node)
1188                 {
1189                         if (existing->flags & EXFAT_ATTRIB_DIR)
1190                         {
1191                                 if (node->flags & EXFAT_ATTRIB_DIR)
1192                                         rc = exfat_rmdir(ef, existing);
1193                                 else
1194                                         rc = -ENOTDIR;
1195                         }
1196                         else
1197                         {
1198                                 if (!(node->flags & EXFAT_ATTRIB_DIR))
1199                                         rc = exfat_unlink(ef, existing);
1200                                 else
1201                                         rc = -EISDIR;
1202                         }
1203                         exfat_put_node(ef, existing);
1204                         if (rc != 0)
1205                         {
1206                                 /* free clusters even if something went wrong; overwise they
1207                                    will be just lost */
1208                                 exfat_cleanup_node(ef, existing);
1209                                 exfat_put_node(ef, dir);
1210                                 exfat_put_node(ef, node);
1211                                 return rc;
1212                         }
1213                         rc = exfat_cleanup_node(ef, existing);
1214                         if (rc != 0)
1215                         {
1216                                 exfat_put_node(ef, dir);
1217                                 exfat_put_node(ef, node);
1218                                 return rc;
1219                         }
1220                 }
1221                 else
1222                         exfat_put_node(ef, existing);
1223         }
1224
1225         rc = find_slot(ef, dir, &cluster, &offset,
1226                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1227         if (rc != 0)
1228         {
1229                 exfat_put_node(ef, dir);
1230                 exfat_put_node(ef, node);
1231                 return rc;
1232         }
1233         rc = rename_entry(ef, dir, node, name, cluster, offset);
1234         exfat_put_node(ef, dir);
1235         exfat_put_node(ef, node);
1236         return rc;
1237 }
1238
1239 void exfat_utimes(struct exfat_node* node, const struct timespec tv[2])
1240 {
1241         node->atime = tv[0].tv_sec;
1242         node->mtime = tv[1].tv_sec;
1243         node->is_dirty = true;
1244 }
1245
1246 void exfat_update_atime(struct exfat_node* node)
1247 {
1248         node->atime = time(NULL);
1249         node->is_dirty = true;
1250 }
1251
1252 void exfat_update_mtime(struct exfat_node* node)
1253 {
1254         node->mtime = time(NULL);
1255         node->is_dirty = true;
1256 }
1257
1258 const char* exfat_get_label(struct exfat* ef)
1259 {
1260         return ef->label;
1261 }
1262
1263 static int find_label(struct exfat* ef, cluster_t* cluster, off_t* offset)
1264 {
1265         struct iterator it;
1266         int rc;
1267
1268         rc = opendir(ef, ef->root, &it);
1269         if (rc != 0)
1270                 return rc;
1271
1272         for (;;)
1273         {
1274                 if (it.offset >= ef->root->size)
1275                 {
1276                         closedir(&it);
1277                         return -ENOENT;
1278                 }
1279
1280                 if (get_entry_ptr(ef, &it)->type == EXFAT_ENTRY_LABEL)
1281                 {
1282                         *cluster = it.cluster;
1283                         *offset = it.offset;
1284                         closedir(&it);
1285                         return 0;
1286                 }
1287
1288                 if (!fetch_next_entry(ef, ef->root, &it))
1289                 {
1290                         closedir(&it);
1291                         return -EIO;
1292                 }
1293         }
1294 }
1295
1296 int exfat_set_label(struct exfat* ef, const char* label)
1297 {
1298         le16_t label_utf16[EXFAT_ENAME_MAX + 1];
1299         int rc;
1300         cluster_t cluster;
1301         off_t offset;
1302         struct exfat_entry_label entry;
1303
1304         memset(label_utf16, 0, sizeof(label_utf16));
1305         rc = utf8_to_utf16(label_utf16, label, EXFAT_ENAME_MAX + 1, strlen(label));
1306         if (rc != 0)
1307                 return rc;
1308
1309         rc = find_label(ef, &cluster, &offset);
1310         if (rc == -ENOENT)
1311                 rc = find_slot(ef, ef->root, &cluster, &offset, 1);
1312         if (rc != 0)
1313                 return rc;
1314
1315         entry.type = EXFAT_ENTRY_LABEL;
1316         entry.length = utf16_length(label_utf16);
1317         memcpy(entry.name, label_utf16, sizeof(entry.name));
1318         if (entry.length == 0)
1319                 entry.type ^= EXFAT_ENTRY_VALID;
1320
1321         if (exfat_pwrite(ef->dev, &entry, sizeof(struct exfat_entry_label),
1322                         co2o(ef, cluster, offset)) < 0)
1323         {
1324                 exfat_error("failed to write label entry");
1325                 return -EIO;
1326         }
1327         strcpy(ef->label, label);
1328         return 0;
1329 }