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[UTF8_BYTES(EXFAT_NAME_MAX) + 1];
  47
  48         --node->references;
  49         if (node->references < 0)
  50         {
  51                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
  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->flags & EXFAT_ATTRIB_DIRTY)
  57                 {
  58                         exfat_get_name(node, buffer, sizeof(buffer) - 1);
  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->flags & EXFAT_ATTRIB_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[UTF8_BYTES(EXFAT_NAME_MAX) + 1];
  98
  99         if (!(dir->flags & EXFAT_ATTRIB_DIR))
 100         {
 101                 exfat_get_name(dir, buffer, sizeof(buffer) - 1);
 102                 exfat_bug("'%s' is not a directory", buffer);
 103         }
 104         if (CLUSTER_INVALID(dir->start_cluster))
 105         {
 106                 exfat_get_name(dir, buffer, sizeof(buffer) - 1);
 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, sizeof(buffer) - 1);
 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         if (meta2->flags & EXFAT_FLAG_CONTIGUOUS)
 198                 node->flags |= EXFAT_ATTRIB_CONTIGUOUS;
 199 }
 200
 201 static const struct exfat_entry* get_entry_ptr(const struct exfat* ef,
 202                 const struct iterator* it)
 203 {
 204         return (const struct exfat_entry*)
 205                         (it->chunk + it->offset % CLUSTER_SIZE(*ef->sb));
 206 }
 207
 208 static bool check_node(const struct exfat_node* node, uint16_t actual_checksum,
 209                 uint16_t reference_checksum, uint64_t valid_size)
 210 {
 211         char buffer[UTF8_BYTES(EXFAT_NAME_MAX) + 1];
 212         bool ret = true;
 213
 214         /*
 215            Validate checksum first. If it's invalid all other fields probably
 216            contain just garbage.
 217         */
 218         if (actual_checksum != reference_checksum)
 219         {
 220                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 221                 exfat_error("'%s' has invalid checksum (%#hx != %#hx)", buffer,
 222                                 actual_checksum, reference_checksum);
 223                 ret = false;
 224         }
 225
 226         /*
 227            exFAT does not support sparse files but allows files with uninitialized
 228            clusters. For such files valid_size means initialized data size and
 229            cannot be greater than file size. See SetFileValidData() function
 230            description in MSDN.
 231         */
 232         if (valid_size > node->size)
 233         {
 234                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 235                 exfat_error("'%s' has valid size (%"PRIu64") greater than size "
 236                                 "(%"PRIu64")", buffer, valid_size, node->size);
 237                 ret = false;
 238         }
 239
 240         /*
 241            Empty file must have zero start cluster. Non-empty file must start
 242            with a valid cluster. Directories cannot be empty (i.e. must always
 243            have a valid start cluster), but we will check this later in opendir()
 244            to give user a chance to read current directory.
 245         */
 246         if (node->size == 0 && node->start_cluster != EXFAT_CLUSTER_FREE)
 247         {
 248                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 249                 exfat_error("'%s' is empty but start cluster is %#x", buffer,
 250                                 node->start_cluster);
 251                 ret = false;
 252         }
 253         if (node->size > 0 && CLUSTER_INVALID(node->start_cluster))
 254         {
 255                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 256                 exfat_error("'%s' points to invalid cluster %#x", buffer,
 257                                 node->start_cluster);
 258                 ret = false;
 259         }
 260
 261         return ret;
 262 }
 263
 264 static void decompress_upcase(uint16_t* output, const le16_t* source,
 265                 size_t size)
 266 {
 267         size_t si;
 268         size_t oi;
 269
 270         for (oi = 0; oi < EXFAT_UPCASE_CHARS; oi++)
 271                 output[oi] = oi;
 272
 273         for (si = 0, oi = 0; si < size && oi < EXFAT_UPCASE_CHARS; si++)
 274         {
 275                 uint16_t ch = le16_to_cpu(source[si]);
 276
 277                 if (ch == 0xffff && si + 1 < size)      /* indicates a run */
 278                         oi += le16_to_cpu(source[++si]);
 279                 else
 280                         output[oi++] = ch;
 281         }
 282 }
 283
 284 /*
 285  * Reads one entry in directory at position pointed by iterator and fills
 286  * node structure.
 287  */
 288 static int readdir(struct exfat* ef, const struct exfat_node* parent,
 289                 struct exfat_node** node, struct iterator* it)
 290 {
 291         int rc = -EIO;
 292         const struct exfat_entry* entry;
 293         const struct exfat_entry_meta1* meta1;
 294         const struct exfat_entry_meta2* meta2;
 295         const struct exfat_entry_name* file_name;
 296         const struct exfat_entry_upcase* upcase;
 297         const struct exfat_entry_bitmap* bitmap;
 298         const struct exfat_entry_label* label;
 299         uint8_t continuations = 0;
 300         le16_t* namep = NULL;
 301         uint16_t reference_checksum = 0;
 302         uint16_t actual_checksum = 0;
 303         uint64_t valid_size = 0;
 304         uint64_t upcase_size = 0;
 305         le16_t* upcase_comp = NULL;
 306
 307         *node = NULL;
 308
 309         for (;;)
 310         {
 311                 if (it->offset >= parent->size)
 312                 {
 313                         if (continuations != 0)
 314                         {
 315                                 exfat_error("expected %hhu continuations", continuations);
 316                                 goto error;
 317                         }
 318                         return -ENOENT; /* that's OK, means end of directory */
 319                 }
 320
 321                 entry = get_entry_ptr(ef, it);
 322                 switch (entry->type)
 323                 {
 324                 case EXFAT_ENTRY_FILE:
 325                         if (continuations != 0)
 326                         {
 327                                 exfat_error("expected %hhu continuations before new entry",
 328                                                 continuations);
 329                                 goto error;
 330                         }
 331                         meta1 = (const struct exfat_entry_meta1*) entry;
 332                         continuations = meta1->continuations;
 333                         /* each file entry must have at least 2 continuations:
 334                            info and name */
 335                         if (continuations < 2)
 336                         {
 337                                 exfat_error("too few continuations (%hhu)", continuations);
 338                                 goto error;
 339                         }
 340                         if (continuations > 1 +
 341                                         DIV_ROUND_UP(EXFAT_NAME_MAX, EXFAT_ENAME_MAX))
 342                         {
 343                                 exfat_error("too many continuations (%hhu)", continuations);
 344                                 goto error;
 345                         }
 346                         reference_checksum = le16_to_cpu(meta1->checksum);
 347                         actual_checksum = exfat_start_checksum(meta1);
 348                         *node = allocate_node();
 349                         if (*node == NULL)
 350                         {
 351                                 rc = -ENOMEM;
 352                                 goto error;
 353                         }
 354                         /* new node has zero reference counter */
 355                         (*node)->entry_cluster = it->cluster;
 356                         (*node)->entry_offset = it->offset;
 357                         init_node_meta1(*node, meta1);
 358                         namep = (*node)->name;
 359                         break;
 360
 361                 case EXFAT_ENTRY_FILE_INFO:
 362                         if (continuations < 2)
 363                         {
 364                                 exfat_error("unexpected continuation (%hhu)",
 365                                                 continuations);
 366                                 goto error;
 367                         }
 368                         meta2 = (const struct exfat_entry_meta2*) entry;
 369                         if (meta2->flags & ~(EXFAT_FLAG_ALWAYS1 | EXFAT_FLAG_CONTIGUOUS))
 370                         {
 371                                 exfat_error("unknown flags in meta2 (0x%hhx)", meta2->flags);
 372                                 goto error;
 373                         }
 374                         init_node_meta2(*node, meta2);
 375                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 376                         valid_size = le64_to_cpu(meta2->valid_size);
 377                         /* empty files must be marked as non-contiguous */
 378                         if ((*node)->size == 0 && (meta2->flags & EXFAT_FLAG_CONTIGUOUS))
 379                         {
 380                                 exfat_error("empty file marked as contiguous (0x%hhx)",
 381                                                 meta2->flags);
 382                                 goto error;
 383                         }
 384                         /* directories must be aligned on at cluster boundary */
 385                         if (((*node)->flags & EXFAT_ATTRIB_DIR) &&
 386                                 (*node)->size % CLUSTER_SIZE(*ef->sb) != 0)
 387                         {
 388                                 exfat_error("directory has invalid size %"PRIu64" bytes",
 389                                                 (*node)->size);
 390                                 goto error;
 391                         }
 392                         --continuations;
 393                         break;
 394
 395                 case EXFAT_ENTRY_FILE_NAME:
 396                         if (continuations == 0)
 397                         {
 398                                 exfat_error("unexpected continuation");
 399                                 goto error;
 400                         }
 401                         file_name = (const struct exfat_entry_name*) entry;
 402                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 403
 404                         memcpy(namep, file_name->name,
 405                                         MIN(EXFAT_ENAME_MAX,
 406                                                 ((*node)->name + EXFAT_NAME_MAX - namep)) *
 407                                         sizeof(le16_t));
 408                         namep += EXFAT_ENAME_MAX;
 409                         if (--continuations == 0)
 410                         {
 411                                 if (!check_node(*node, actual_checksum, reference_checksum,
 412                                                 valid_size))
 413                                         goto error;
 414                                 if (!fetch_next_entry(ef, parent, it))
 415                                         goto error;
 416                                 return 0; /* entry completed */
 417                         }
 418                         break;
 419
 420                 case EXFAT_ENTRY_UPCASE:
 421                         if (ef->upcase != NULL)
 422                                 break;
 423                         upcase = (const struct exfat_entry_upcase*) entry;
 424                         if (CLUSTER_INVALID(le32_to_cpu(upcase->start_cluster)))
 425                         {
 426                                 exfat_error("invalid cluster 0x%x in upcase table",
 427                                                 le32_to_cpu(upcase->start_cluster));
 428                                 goto error;
 429                         }
 430                         upcase_size = le64_to_cpu(upcase->size);
 431                         if (upcase_size == 0 ||
 432                                 upcase_size > EXFAT_UPCASE_CHARS * sizeof(uint16_t) ||
 433                                 upcase_size % sizeof(uint16_t) != 0)
 434                         {
 435                                 exfat_error("bad upcase table size (%"PRIu64" bytes)",
 436                                                 upcase_size);
 437                                 goto error;
 438                         }
 439                         upcase_comp = malloc(upcase_size);
 440                         if (upcase_comp == NULL)
 441                         {
 442                                 exfat_error("failed to allocate upcase table (%"PRIu64" bytes)",
 443                                                 upcase_size);
 444                                 rc = -ENOMEM;
 445                                 goto error;
 446                         }
 447
 448                         /* read compressed upcase table */
 449                         if (exfat_pread(ef->dev, upcase_comp, upcase_size,
 450                                         exfat_c2o(ef, le32_to_cpu(upcase->start_cluster))) < 0)
 451                         {
 452                                 free(upcase_comp);
 453                                 exfat_error("failed to read upper case table "
 454                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 455                                                 upcase_size,
 456                                                 le32_to_cpu(upcase->start_cluster));
 457                                 goto error;
 458                         }
 459
 460                         /* decompress upcase table */
 461                         ef->upcase = calloc(EXFAT_UPCASE_CHARS, sizeof(uint16_t));
 462                         if (ef->upcase == NULL)
 463                         {
 464                                 free(upcase_comp);
 465                                 exfat_error("failed to allocate decompressed upcase table");
 466                                 rc = -ENOMEM;
 467                                 goto error;
 468                         }
 469                         decompress_upcase(ef->upcase, upcase_comp,
 470                                         upcase_size / sizeof(uint16_t));
 471                         free(upcase_comp);
 472                         break;
 473
 474                 case EXFAT_ENTRY_BITMAP:
 475                         bitmap = (const struct exfat_entry_bitmap*) entry;
 476                         ef->cmap.start_cluster = le32_to_cpu(bitmap->start_cluster);
 477                         if (CLUSTER_INVALID(ef->cmap.start_cluster))
 478                         {
 479                                 exfat_error("invalid cluster 0x%x in clusters bitmap",
 480                                                 ef->cmap.start_cluster);
 481                                 goto error;
 482                         }
 483                         ef->cmap.size = le32_to_cpu(ef->sb->cluster_count) -
 484                                 EXFAT_FIRST_DATA_CLUSTER;
 485                         if (le64_to_cpu(bitmap->size) < DIV_ROUND_UP(ef->cmap.size, 8))
 486                         {
 487                                 exfat_error("invalid clusters bitmap size: %"PRIu64
 488                                                 " (expected at least %u)",
 489                                                 le64_to_cpu(bitmap->size),
 490                                                 DIV_ROUND_UP(ef->cmap.size, 8));
 491                                 goto error;
 492                         }
 493                         /* FIXME bitmap can be rather big, up to 512 MB */
 494                         ef->cmap.chunk_size = ef->cmap.size;
 495                         ef->cmap.chunk = malloc(BMAP_SIZE(ef->cmap.chunk_size));
 496                         if (ef->cmap.chunk == NULL)
 497                         {
 498                                 exfat_error("failed to allocate clusters bitmap chunk "
 499                                                 "(%"PRIu64" bytes)", le64_to_cpu(bitmap->size));
 500                                 rc = -ENOMEM;
 501                                 goto error;
 502                         }
 503
 504                         if (exfat_pread(ef->dev, ef->cmap.chunk,
 505                                         BMAP_SIZE(ef->cmap.chunk_size),
 506                                         exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
 507                         {
 508                                 exfat_error("failed to read clusters bitmap "
 509                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 510                                                 le64_to_cpu(bitmap->size), ef->cmap.start_cluster);
 511                                 goto error;
 512                         }
 513                         break;
 514
 515                 case EXFAT_ENTRY_LABEL:
 516                         label = (const struct exfat_entry_label*) entry;
 517                         if (label->length > EXFAT_ENAME_MAX)
 518                         {
 519                                 exfat_error("too long label (%hhu chars)", label->length);
 520                                 goto error;
 521                         }
 522                         if (utf16_to_utf8(ef->label, label->name,
 523                                                 sizeof(ef->label) - 1, EXFAT_ENAME_MAX) != 0)
 524                                 goto error;
 525                         break;
 526
 527                 default:
 528                         if (!(entry->type & EXFAT_ENTRY_VALID))
 529                                 break; /* deleted entry, ignore it */
 530                         if (!(entry->type & EXFAT_ENTRY_OPTIONAL))
 531                         {
 532                                 exfat_error("unknown entry type %#hhx", entry->type);
 533                                 goto error;
 534                         }
 535                         /* optional entry, warn and skip */
 536                         exfat_warn("unknown entry type %#hhx", entry->type);
 537                         if (continuations == 0)
 538                         {
 539                                 exfat_error("unexpected continuation");
 540                                 goto error;
 541                         }
 542                         --continuations;
 543                         break;
 544                 }
 545
 546                 if (!fetch_next_entry(ef, parent, it))
 547                         goto error;
 548         }
 549         /* we never reach here */
 550
 551 error:
 552         free(*node);
 553         *node = NULL;
 554         return rc;
 555 }
 556
 557 int exfat_cache_directory(struct exfat* ef, struct exfat_node* dir)
 558 {
 559         struct iterator it;
 560         int rc;
 561         struct exfat_node* node;
 562         struct exfat_node* current = NULL;
 563
 564         if (dir->flags & EXFAT_ATTRIB_CACHED)
 565                 return 0; /* already cached */
 566
 567         rc = opendir(ef, dir, &it);
 568         if (rc != 0)
 569                 return rc;
 570         while ((rc = readdir(ef, dir, &node, &it)) == 0)
 571         {
 572                 node->parent = dir;
 573                 if (current != NULL)
 574                 {
 575                         current->next = node;
 576                         node->prev = current;
 577                 }
 578                 else
 579                         dir->child = node;
 580
 581                 current = node;
 582         }
 583         closedir(&it);
 584
 585         if (rc != -ENOENT)
 586         {
 587                 /* rollback */
 588                 for (current = dir->child; current; current = node)
 589                 {
 590                         node = current->next;
 591                         free(current);
 592                 }
 593                 dir->child = NULL;
 594                 return rc;
 595         }
 596
 597         dir->flags |= EXFAT_ATTRIB_CACHED;
 598         return 0;
 599 }
 600
 601 static void tree_attach(struct exfat_node* dir, struct exfat_node* node)
 602 {
 603         node->parent = dir;
 604         if (dir->child)
 605         {
 606                 dir->child->prev = node;
 607                 node->next = dir->child;
 608         }
 609         dir->child = node;
 610 }
 611
 612 static void tree_detach(struct exfat_node* node)
 613 {
 614         if (node->prev)
 615                 node->prev->next = node->next;
 616         else /* this is the first node in the list */
 617                 node->parent->child = node->next;
 618         if (node->next)
 619                 node->next->prev = node->prev;
 620         node->parent = NULL;
 621         node->prev = NULL;
 622         node->next = NULL;
 623 }
 624
 625 static void reset_cache(struct exfat* ef, struct exfat_node* node)
 626 {
 627         char buffer[UTF8_BYTES(EXFAT_NAME_MAX) + 1];
 628
 629         while (node->child)
 630         {
 631                 struct exfat_node* p = node->child;
 632                 reset_cache(ef, p);
 633                 tree_detach(p);
 634                 free(p);
 635         }
 636         node->flags &= ~EXFAT_ATTRIB_CACHED;
 637         if (node->references != 0)
 638         {
 639                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 640                 exfat_warn("non-zero reference counter (%d) for '%s'",
 641                                 node->references, buffer);
 642         }
 643         if (node != ef->root && (node->flags & EXFAT_ATTRIB_DIRTY))
 644         {
 645                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 646                 exfat_bug("node '%s' is dirty", buffer);
 647         }
 648         while (node->references)
 649                 exfat_put_node(ef, node);
 650 }
 651
 652 void exfat_reset_cache(struct exfat* ef)
 653 {
 654         reset_cache(ef, ef->root);
 655 }
 656
 657 static bool next_entry(struct exfat* ef, const struct exfat_node* parent,
 658                 cluster_t* cluster, off_t* offset)
 659 {
 660         *offset += sizeof(struct exfat_entry);
 661         if (*offset % CLUSTER_SIZE(*ef->sb) == 0)
 662         {
 663                 *cluster = exfat_next_cluster(ef, parent, *cluster);
 664                 if (CLUSTER_INVALID(*cluster))
 665                 {
 666                         exfat_error("invalid cluster %#x while getting next entry",
 667                                         *cluster);
 668                         return false;
 669                 }
 670         }
 671         return true;
 672 }
 673
 674 int exfat_flush_node(struct exfat* ef, struct exfat_node* node)
 675 {
 676         cluster_t cluster;
 677         off_t offset;
 678         off_t meta1_offset, meta2_offset;
 679         struct exfat_entry_meta1 meta1;
 680         struct exfat_entry_meta2 meta2;
 681
 682         if (!(node->flags & EXFAT_ATTRIB_DIRTY))
 683                 return 0; /* no need to flush */
 684
 685         if (ef->ro)
 686                 exfat_bug("unable to flush node to read-only FS");
 687
 688         if (node->parent == NULL)
 689                 return 0; /* do not flush unlinked node */
 690
 691         cluster = node->entry_cluster;
 692         offset = node->entry_offset;
 693         meta1_offset = co2o(ef, cluster, offset);
 694         if (!next_entry(ef, node->parent, &cluster, &offset))
 695                 return -EIO;
 696         meta2_offset = co2o(ef, cluster, offset);
 697
 698         if (exfat_pread(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 699         {
 700                 exfat_error("failed to read meta1 entry on flush");
 701                 return -EIO;
 702         }
 703         if (meta1.type != EXFAT_ENTRY_FILE)
 704                 exfat_bug("invalid type of meta1: 0x%hhx", meta1.type);
 705         meta1.attrib = cpu_to_le16(node->flags);
 706         exfat_unix2exfat(node->mtime, &meta1.mdate, &meta1.mtime, &meta1.mtime_cs);
 707         exfat_unix2exfat(node->atime, &meta1.adate, &meta1.atime, NULL);
 708
 709         if (exfat_pread(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 710         {
 711                 exfat_error("failed to read meta2 entry on flush");
 712                 return -EIO;
 713         }
 714         if (meta2.type != EXFAT_ENTRY_FILE_INFO)
 715                 exfat_bug("invalid type of meta2: 0x%hhx", meta2.type);
 716         meta2.size = meta2.valid_size = cpu_to_le64(node->size);
 717         meta2.start_cluster = cpu_to_le32(node->start_cluster);
 718         meta2.flags = EXFAT_FLAG_ALWAYS1;
 719         /* empty files must not be marked as contiguous */
 720         if (node->size != 0 && IS_CONTIGUOUS(*node))
 721                 meta2.flags |= EXFAT_FLAG_CONTIGUOUS;
 722         /* name hash remains unchanged, no need to recalculate it */
 723
 724         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 725
 726         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 727         {
 728                 exfat_error("failed to write meta1 entry on flush");
 729                 return -EIO;
 730         }
 731         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 732         {
 733                 exfat_error("failed to write meta2 entry on flush");
 734                 return -EIO;
 735         }
 736
 737         node->flags &= ~EXFAT_ATTRIB_DIRTY;
 738         return exfat_flush(ef);
 739 }
 740
 741 static bool erase_entry(struct exfat* ef, struct exfat_node* node)
 742 {
 743         cluster_t cluster = node->entry_cluster;
 744         off_t offset = node->entry_offset;
 745         int name_entries = DIV_ROUND_UP(utf16_length(node->name), EXFAT_ENAME_MAX);
 746         uint8_t entry_type;
 747
 748         entry_type = EXFAT_ENTRY_FILE & ~EXFAT_ENTRY_VALID;
 749         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 750         {
 751                 exfat_error("failed to erase meta1 entry");
 752                 return false;
 753         }
 754
 755         if (!next_entry(ef, node->parent, &cluster, &offset))
 756                 return false;
 757         entry_type = EXFAT_ENTRY_FILE_INFO & ~EXFAT_ENTRY_VALID;
 758         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 759         {
 760                 exfat_error("failed to erase meta2 entry");
 761                 return false;
 762         }
 763
 764         while (name_entries--)
 765         {
 766                 if (!next_entry(ef, node->parent, &cluster, &offset))
 767                         return false;
 768                 entry_type = EXFAT_ENTRY_FILE_NAME & ~EXFAT_ENTRY_VALID;
 769                 if (exfat_pwrite(ef->dev, &entry_type, 1,
 770                                 co2o(ef, cluster, offset)) < 0)
 771                 {
 772                         exfat_error("failed to erase name entry");
 773                         return false;
 774                 }
 775         }
 776         return true;
 777 }
 778
 779 static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
 780                 off_t deleted_offset)
 781 {
 782         const struct exfat_node* node;
 783         const struct exfat_node* last_node;
 784         uint64_t entries = 0;
 785         uint64_t new_size;
 786
 787         if (!(dir->flags & EXFAT_ATTRIB_DIR))
 788                 exfat_bug("attempted to shrink a file");
 789         if (!(dir->flags & EXFAT_ATTRIB_CACHED))
 790                 exfat_bug("attempted to shrink uncached directory");
 791
 792         for (last_node = node = dir->child; node; node = node->next)
 793         {
 794                 if (deleted_offset < node->entry_offset)
 795                 {
 796                         /* there are other entries after the removed one, no way to shrink
 797                            this directory */
 798                         return 0;
 799                 }
 800                 if (last_node->entry_offset < node->entry_offset)
 801                         last_node = node;
 802         }
 803
 804         if (last_node)
 805         {
 806                 /* offset of the last entry */
 807                 entries += last_node->entry_offset / sizeof(struct exfat_entry);
 808                 /* two subentries with meta info */
 809                 entries += 2;
 810                 /* subentries with file name */
 811                 entries += DIV_ROUND_UP(utf16_length(last_node->name),
 812                                 EXFAT_ENAME_MAX);
 813         }
 814
 815         new_size = DIV_ROUND_UP(entries * sizeof(struct exfat_entry),
 816                                  CLUSTER_SIZE(*ef->sb)) * CLUSTER_SIZE(*ef->sb);
 817         if (new_size == 0) /* directory always has at least 1 cluster */
 818                 new_size = CLUSTER_SIZE(*ef->sb);
 819         if (new_size == dir->size)
 820                 return 0;
 821         return exfat_truncate(ef, dir, new_size, true);
 822 }
 823
 824 static int delete(struct exfat* ef, struct exfat_node* node)
 825 {
 826         struct exfat_node* parent = node->parent;
 827         off_t deleted_offset = node->entry_offset;
 828         int rc;
 829
 830         exfat_get_node(parent);
 831         if (!erase_entry(ef, node))
 832         {
 833                 exfat_put_node(ef, parent);
 834                 return -EIO;
 835         }
 836         exfat_update_mtime(parent);
 837         tree_detach(node);
 838         rc = shrink_directory(ef, parent, deleted_offset);
 839         node->flags |= EXFAT_ATTRIB_UNLINKED;
 840         if (rc != 0)
 841         {
 842                 exfat_flush_node(ef, parent);
 843                 exfat_put_node(ef, parent);
 844                 return rc;
 845         }
 846         rc = exfat_flush_node(ef, parent);
 847         exfat_put_node(ef, parent);
 848         return rc;
 849 }
 850
 851 int exfat_unlink(struct exfat* ef, struct exfat_node* node)
 852 {
 853         if (node->flags & EXFAT_ATTRIB_DIR)
 854                 return -EISDIR;
 855         return delete(ef, node);
 856 }
 857
 858 int exfat_rmdir(struct exfat* ef, struct exfat_node* node)
 859 {
 860         int rc;
 861
 862         if (!(node->flags & EXFAT_ATTRIB_DIR))
 863                 return -ENOTDIR;
 864         /* check that directory is empty */
 865         rc = exfat_cache_directory(ef, node);
 866         if (rc != 0)
 867                 return rc;
 868         if (node->child)
 869                 return -ENOTEMPTY;
 870         return delete(ef, node);
 871 }
 872
 873 static int grow_directory(struct exfat* ef, struct exfat_node* dir,
 874                 uint64_t asize, uint32_t difference)
 875 {
 876         return exfat_truncate(ef, dir,
 877                         DIV_ROUND_UP(asize + difference, CLUSTER_SIZE(*ef->sb))
 878                                 * CLUSTER_SIZE(*ef->sb), true);
 879 }
 880
 881 static int find_slot(struct exfat* ef, struct exfat_node* dir,
 882                 cluster_t* cluster, off_t* offset, int subentries)
 883 {
 884         struct iterator it;
 885         int rc;
 886         const struct exfat_entry* entry;
 887         int contiguous = 0;
 888
 889         rc = opendir(ef, dir, &it);
 890         if (rc != 0)
 891                 return rc;
 892         for (;;)
 893         {
 894                 if (contiguous == 0)
 895                 {
 896                         *cluster = it.cluster;
 897                         *offset = it.offset;
 898                 }
 899                 entry = get_entry_ptr(ef, &it);
 900                 if (entry->type & EXFAT_ENTRY_VALID)
 901                         contiguous = 0;
 902                 else
 903                         contiguous++;
 904                 if (contiguous == subentries)
 905                         break;  /* suitable slot is found */
 906                 if (it.offset + sizeof(struct exfat_entry) >= dir->size)
 907                 {
 908                         rc = grow_directory(ef, dir, dir->size,
 909                                         (subentries - contiguous) * sizeof(struct exfat_entry));
 910                         if (rc != 0)
 911                         {
 912                                 closedir(&it);
 913                                 return rc;
 914                         }
 915                 }
 916                 if (!fetch_next_entry(ef, dir, &it))
 917                 {
 918                         closedir(&it);
 919                         return -EIO;
 920                 }
 921         }
 922         closedir(&it);
 923         return 0;
 924 }
 925
 926 static int write_entry(struct exfat* ef, struct exfat_node* dir,
 927                 const le16_t* name, cluster_t cluster, off_t offset, uint16_t attrib)
 928 {
 929         struct exfat_node* node;
 930         struct exfat_entry_meta1 meta1;
 931         struct exfat_entry_meta2 meta2;
 932         const size_t name_length = utf16_length(name);
 933         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
 934         int i;
 935
 936         node = allocate_node();
 937         if (node == NULL)
 938                 return -ENOMEM;
 939         node->entry_cluster = cluster;
 940         node->entry_offset = offset;
 941         memcpy(node->name, name, name_length * sizeof(le16_t));
 942
 943         memset(&meta1, 0, sizeof(meta1));
 944         meta1.type = EXFAT_ENTRY_FILE;
 945         meta1.continuations = 1 + name_entries;
 946         meta1.attrib = cpu_to_le16(attrib);
 947         exfat_unix2exfat(time(NULL), &meta1.crdate, &meta1.crtime,
 948                         &meta1.crtime_cs);
 949         meta1.adate = meta1.mdate = meta1.crdate;
 950         meta1.atime = meta1.mtime = meta1.crtime;
 951         meta1.mtime_cs = meta1.crtime_cs; /* there is no atime_cs */
 952
 953         memset(&meta2, 0, sizeof(meta2));
 954         meta2.type = EXFAT_ENTRY_FILE_INFO;
 955         meta2.flags = EXFAT_FLAG_ALWAYS1;
 956         meta2.name_length = name_length;
 957         meta2.name_hash = exfat_calc_name_hash(ef, node->name);
 958         meta2.start_cluster = cpu_to_le32(EXFAT_CLUSTER_FREE);
 959
 960         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 961
 962         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
 963                         co2o(ef, cluster, offset)) < 0)
 964         {
 965                 exfat_error("failed to write meta1 entry");
 966                 return -EIO;
 967         }
 968         if (!next_entry(ef, dir, &cluster, &offset))
 969                 return -EIO;
 970         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
 971                         co2o(ef, cluster, offset)) < 0)
 972         {
 973                 exfat_error("failed to write meta2 entry");
 974                 return -EIO;
 975         }
 976         for (i = 0; i < name_entries; i++)
 977         {
 978                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
 979                 memcpy(name_entry.name, node->name + i * EXFAT_ENAME_MAX,
 980                                 MIN(EXFAT_ENAME_MAX, EXFAT_NAME_MAX - i * EXFAT_ENAME_MAX) *
 981                                 sizeof(le16_t));
 982                 if (!next_entry(ef, dir, &cluster, &offset))
 983                         return -EIO;
 984                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
 985                                 co2o(ef, cluster, offset)) < 0)
 986                 {
 987                         exfat_error("failed to write name entry");
 988                         return -EIO;
 989                 }
 990         }
 991
 992         init_node_meta1(node, &meta1);
 993         init_node_meta2(node, &meta2);
 994
 995         tree_attach(dir, node);
 996         exfat_update_mtime(dir);
 997         return 0;
 998 }
 999
1000 static int create(struct exfat* ef, const char* path, uint16_t attrib)
1001 {
1002         struct exfat_node* dir;
1003         struct exfat_node* existing;
1004         cluster_t cluster = EXFAT_CLUSTER_BAD;
1005         off_t offset = -1;
1006         le16_t name[EXFAT_NAME_MAX + 1];
1007         int rc;
1008
1009         rc = exfat_split(ef, &dir, &existing, name, path);
1010         if (rc != 0)
1011                 return rc;
1012         if (existing != NULL)
1013         {
1014                 exfat_put_node(ef, existing);
1015                 exfat_put_node(ef, dir);
1016                 return -EEXIST;
1017         }
1018
1019         rc = find_slot(ef, dir, &cluster, &offset,
1020                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1021         if (rc != 0)
1022         {
1023                 exfat_put_node(ef, dir);
1024                 return rc;
1025         }
1026         rc = write_entry(ef, dir, name, cluster, offset, attrib);
1027         if (rc != 0)
1028         {
1029                 exfat_put_node(ef, dir);
1030                 return rc;
1031         }
1032         rc = exfat_flush_node(ef, dir);
1033         exfat_put_node(ef, dir);
1034         return rc;
1035 }
1036
1037 int exfat_mknod(struct exfat* ef, const char* path)
1038 {
1039         return create(ef, path, EXFAT_ATTRIB_ARCH);
1040 }
1041
1042 int exfat_mkdir(struct exfat* ef, const char* path)
1043 {
1044         int rc;
1045         struct exfat_node* node;
1046
1047         rc = create(ef, path, EXFAT_ATTRIB_DIR);
1048         if (rc != 0)
1049                 return rc;
1050         rc = exfat_lookup(ef, &node, path);
1051         if (rc != 0)
1052                 return 0;
1053         /* directories always have at least one cluster */
1054         rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
1055         if (rc != 0)
1056         {
1057                 delete(ef, node);
1058                 exfat_put_node(ef, node);
1059                 return rc;
1060         }
1061         rc = exfat_flush_node(ef, node);
1062         if (rc != 0)
1063         {
1064                 delete(ef, node);
1065                 exfat_put_node(ef, node);
1066                 return rc;
1067         }
1068         exfat_put_node(ef, node);
1069         return 0;
1070 }
1071
1072 static int rename_entry(struct exfat* ef, struct exfat_node* dir,
1073                 struct exfat_node* node, const le16_t* name, cluster_t new_cluster,
1074                 off_t new_offset)
1075 {
1076         struct exfat_entry_meta1 meta1;
1077         struct exfat_entry_meta2 meta2;
1078         cluster_t old_cluster = node->entry_cluster;
1079         off_t old_offset = node->entry_offset;
1080         const size_t name_length = utf16_length(name);
1081         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
1082         int i;
1083
1084         if (exfat_pread(ef->dev, &meta1, sizeof(meta1),
1085                         co2o(ef, old_cluster, old_offset)) < 0)
1086         {
1087                 exfat_error("failed to read meta1 entry on rename");
1088                 return -EIO;
1089         }
1090         if (!next_entry(ef, node->parent, &old_cluster, &old_offset))
1091                 return -EIO;
1092         if (exfat_pread(ef->dev, &meta2, sizeof(meta2),
1093                         co2o(ef, old_cluster, old_offset)) < 0)
1094         {
1095                 exfat_error("failed to read meta2 entry on rename");
1096                 return -EIO;
1097         }
1098         meta1.continuations = 1 + name_entries;
1099         meta2.name_hash = exfat_calc_name_hash(ef, name);
1100         meta2.name_length = name_length;
1101         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, name);
1102
1103         if (!erase_entry(ef, node))
1104                 return -EIO;
1105
1106         node->entry_cluster = new_cluster;
1107         node->entry_offset = new_offset;
1108
1109         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
1110                         co2o(ef, new_cluster, new_offset)) < 0)
1111         {
1112                 exfat_error("failed to write meta1 entry on rename");
1113                 return -EIO;
1114         }
1115         if (!next_entry(ef, dir, &new_cluster, &new_offset))
1116                 return -EIO;
1117         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
1118                         co2o(ef, new_cluster, new_offset)) < 0)
1119         {
1120                 exfat_error("failed to write meta2 entry on rename");
1121                 return -EIO;
1122         }
1123
1124         for (i = 0; i < name_entries; i++)
1125         {
1126                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
1127                 memcpy(name_entry.name, name + i * EXFAT_ENAME_MAX,
1128                                 EXFAT_ENAME_MAX * sizeof(le16_t));
1129                 if (!next_entry(ef, dir, &new_cluster, &new_offset))
1130                         return -EIO;
1131                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
1132                                 co2o(ef, new_cluster, new_offset)) < 0)
1133                 {
1134                         exfat_error("failed to write name entry on rename");
1135                         return -EIO;
1136                 }
1137         }
1138
1139         memcpy(node->name, name, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
1140         tree_detach(node);
1141         tree_attach(dir, node);
1142         return 0;
1143 }
1144
1145 int exfat_rename(struct exfat* ef, const char* old_path, const char* new_path)
1146 {
1147         struct exfat_node* node;
1148         struct exfat_node* existing;
1149         struct exfat_node* dir;
1150         cluster_t cluster = EXFAT_CLUSTER_BAD;
1151         off_t offset = -1;
1152         le16_t name[EXFAT_NAME_MAX + 1];
1153         int rc;
1154
1155         rc = exfat_lookup(ef, &node, old_path);
1156         if (rc != 0)
1157                 return rc;
1158
1159         rc = exfat_split(ef, &dir, &existing, name, new_path);
1160         if (rc != 0)
1161         {
1162                 exfat_put_node(ef, node);
1163                 return rc;
1164         }
1165
1166         /* check that target is not a subdirectory of the source */
1167         if (node->flags & EXFAT_ATTRIB_DIR)
1168         {
1169                 struct exfat_node* p;
1170
1171                 for (p = dir; p; p = p->parent)
1172                         if (node == p)
1173                         {
1174                                 if (existing != NULL)
1175                                         exfat_put_node(ef, existing);
1176                                 exfat_put_node(ef, dir);
1177                                 exfat_put_node(ef, node);
1178                                 return -EINVAL;
1179                         }
1180         }
1181
1182         if (existing != NULL)
1183         {
1184                 /* remove target if it's not the same node as source */
1185                 if (existing != node)
1186                 {
1187                         if (existing->flags & EXFAT_ATTRIB_DIR)
1188                         {
1189                                 if (node->flags & EXFAT_ATTRIB_DIR)
1190                                         rc = exfat_rmdir(ef, existing);
1191                                 else
1192                                         rc = -ENOTDIR;
1193                         }
1194                         else
1195                         {
1196                                 if (!(node->flags & EXFAT_ATTRIB_DIR))
1197                                         rc = exfat_unlink(ef, existing);
1198                                 else
1199                                         rc = -EISDIR;
1200                         }
1201                         exfat_put_node(ef, existing);
1202                         if (rc != 0)
1203                         {
1204                                 /* free clusters even if something went wrong; overwise they
1205                                    will be just lost */
1206                                 exfat_cleanup_node(ef, existing);
1207                                 exfat_put_node(ef, dir);
1208                                 exfat_put_node(ef, node);
1209                                 return rc;
1210                         }
1211                         rc = exfat_cleanup_node(ef, existing);
1212                         if (rc != 0)
1213                         {
1214                                 exfat_put_node(ef, dir);
1215                                 exfat_put_node(ef, node);
1216                                 return rc;
1217                         }
1218                 }
1219                 else
1220                         exfat_put_node(ef, existing);
1221         }
1222
1223         rc = find_slot(ef, dir, &cluster, &offset,
1224                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1225         if (rc != 0)
1226         {
1227                 exfat_put_node(ef, dir);
1228                 exfat_put_node(ef, node);
1229                 return rc;
1230         }
1231         rc = rename_entry(ef, dir, node, name, cluster, offset);
1232         exfat_put_node(ef, dir);
1233         exfat_put_node(ef, node);
1234         return rc;
1235 }
1236
1237 void exfat_utimes(struct exfat_node* node, const struct timespec tv[2])
1238 {
1239         node->atime = tv[0].tv_sec;
1240         node->mtime = tv[1].tv_sec;
1241         node->flags |= EXFAT_ATTRIB_DIRTY;
1242 }
1243
1244 void exfat_update_atime(struct exfat_node* node)
1245 {
1246         node->atime = time(NULL);
1247         node->flags |= EXFAT_ATTRIB_DIRTY;
1248 }
1249
1250 void exfat_update_mtime(struct exfat_node* node)
1251 {
1252         node->mtime = time(NULL);
1253         node->flags |= EXFAT_ATTRIB_DIRTY;
1254 }
1255
1256 const char* exfat_get_label(struct exfat* ef)
1257 {
1258         return ef->label;
1259 }
1260
1261 static int find_label(struct exfat* ef, cluster_t* cluster, off_t* offset)
1262 {
1263         struct iterator it;
1264         int rc;
1265
1266         rc = opendir(ef, ef->root, &it);
1267         if (rc != 0)
1268                 return rc;
1269
1270         for (;;)
1271         {
1272                 if (it.offset >= ef->root->size)
1273                 {
1274                         closedir(&it);
1275                         return -ENOENT;
1276                 }
1277
1278                 if (get_entry_ptr(ef, &it)->type == EXFAT_ENTRY_LABEL)
1279                 {
1280                         *cluster = it.cluster;
1281                         *offset = it.offset;
1282                         closedir(&it);
1283                         return 0;
1284                 }
1285
1286                 if (!fetch_next_entry(ef, ef->root, &it))
1287                 {
1288                         closedir(&it);
1289                         return -EIO;
1290                 }
1291         }
1292 }
1293
1294 int exfat_set_label(struct exfat* ef, const char* label)
1295 {
1296         le16_t label_utf16[EXFAT_ENAME_MAX + 1];
1297         int rc;
1298         cluster_t cluster;
1299         off_t offset;
1300         struct exfat_entry_label entry;
1301
1302         memset(label_utf16, 0, sizeof(label_utf16));
1303         rc = utf8_to_utf16(label_utf16, label, EXFAT_ENAME_MAX, strlen(label));
1304         if (rc != 0)
1305                 return rc;
1306
1307         rc = find_label(ef, &cluster, &offset);
1308         if (rc == -ENOENT)
1309                 rc = find_slot(ef, ef->root, &cluster, &offset, 1);
1310         if (rc != 0)
1311                 return rc;
1312
1313         entry.type = EXFAT_ENTRY_LABEL;
1314         entry.length = utf16_length(label_utf16);
1315         memcpy(entry.name, label_utf16, sizeof(entry.name));
1316         if (entry.length == 0)
1317                 entry.type ^= EXFAT_ENTRY_VALID;
1318
1319         if (exfat_pwrite(ef->dev, &entry, sizeof(struct exfat_entry_label),
1320                         co2o(ef, cluster, offset)) < 0)
1321         {
1322                 exfat_error("failed to write label entry");
1323                 return -EIO;
1324         }
1325         strcpy(ef->label, label);
1326         return 0;
1327 }