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->attrib & 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 int read_entries(struct exfat* ef, struct exfat_node* dir,
 170                 struct exfat_entry* entries, int n, off_t offset)
 171 {
 172         ssize_t size;
 173
 174         if (!(dir->attrib & EXFAT_ATTRIB_DIR))
 175                 exfat_bug("attempted to read entries from a file");
 176
 177         size = exfat_generic_pread(ef, dir, entries,
 178                         sizeof(struct exfat_entry[n]), offset);
 179         if (size == sizeof(struct exfat_entry[n]))
 180                 return 0; /* success */
 181         if (size == 0)
 182                 return -ENOENT;
 183         if (size < 0)
 184                 return -EIO;
 185         exfat_error("read %zd bytes instead of %zu bytes", size,
 186                         sizeof(struct exfat_entry[n]));
 187         return -EIO;
 188 }
 189
 190 static int write_entries(struct exfat* ef, struct exfat_node* dir,
 191                 const struct exfat_entry* entries, int n, off_t offset)
 192 {
 193         ssize_t size;
 194
 195         if (!(dir->attrib & EXFAT_ATTRIB_DIR))
 196                 exfat_bug("attempted to write entries into a file");
 197
 198         size = exfat_generic_pwrite(ef, dir, entries,
 199                         sizeof(struct exfat_entry[n]), offset);
 200         if (size == sizeof(struct exfat_entry[n]))
 201                 return 0; /* success */
 202         if (size < 0)
 203                 return -EIO;
 204         exfat_error("wrote %zd bytes instead of %zu bytes", size,
 205                         sizeof(struct exfat_entry[n]));
 206         return -EIO;
 207 }
 208
 209 static struct exfat_node* allocate_node(void)
 210 {
 211         struct exfat_node* node = malloc(sizeof(struct exfat_node));
 212         if (node == NULL)
 213         {
 214                 exfat_error("failed to allocate node");
 215                 return NULL;
 216         }
 217         memset(node, 0, sizeof(struct exfat_node));
 218         return node;
 219 }
 220
 221 static void init_node_meta1(struct exfat_node* node,
 222                 const struct exfat_entry_meta1* meta1)
 223 {
 224         node->attrib = le16_to_cpu(meta1->attrib);
 225         node->mtime = exfat_exfat2unix(meta1->mdate, meta1->mtime,
 226                         meta1->mtime_cs);
 227         /* there is no centiseconds field for atime */
 228         node->atime = exfat_exfat2unix(meta1->adate, meta1->atime, 0);
 229 }
 230
 231 static void init_node_meta2(struct exfat_node* node,
 232                 const struct exfat_entry_meta2* meta2)
 233 {
 234         node->size = le64_to_cpu(meta2->size);
 235         node->start_cluster = le32_to_cpu(meta2->start_cluster);
 236         node->fptr_cluster = node->start_cluster;
 237         node->is_contiguous = ((meta2->flags & EXFAT_FLAG_CONTIGUOUS) != 0);
 238 }
 239
 240 static const struct exfat_entry* get_entry_ptr(const struct exfat* ef,
 241                 const struct iterator* it)
 242 {
 243         return (const struct exfat_entry*)
 244                         (it->chunk + it->offset % CLUSTER_SIZE(*ef->sb));
 245 }
 246
 247 static bool check_node(const struct exfat_node* node, uint16_t actual_checksum,
 248                 uint16_t reference_checksum, uint64_t valid_size, int cluster_size)
 249 {
 250         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
 251         bool ret = true;
 252
 253         /*
 254            Validate checksum first. If it's invalid all other fields probably
 255            contain just garbage.
 256         */
 257         if (actual_checksum != reference_checksum)
 258         {
 259                 exfat_get_name(node, buffer);
 260                 exfat_error("'%s' has invalid checksum (%#hx != %#hx)", buffer,
 261                                 actual_checksum, reference_checksum);
 262                 ret = false;
 263         }
 264
 265         /*
 266            exFAT does not support sparse files but allows files with uninitialized
 267            clusters. For such files valid_size means initialized data size and
 268            cannot be greater than file size. See SetFileValidData() function
 269            description in MSDN.
 270         */
 271         if (valid_size > node->size)
 272         {
 273                 exfat_get_name(node, buffer);
 274                 exfat_error("'%s' has valid size (%"PRIu64") greater than size "
 275                                 "(%"PRIu64")", buffer, valid_size, node->size);
 276                 ret = false;
 277         }
 278
 279         /*
 280            Empty file must have zero start cluster. Non-empty file must start
 281            with a valid cluster. Directories cannot be empty (i.e. must always
 282            have a valid start cluster), but we will check this later in opendir()
 283            to give user a chance to read current directory.
 284         */
 285         if (node->size == 0 && node->start_cluster != EXFAT_CLUSTER_FREE)
 286         {
 287                 exfat_get_name(node, buffer);
 288                 exfat_error("'%s' is empty but start cluster is %#x", buffer,
 289                                 node->start_cluster);
 290                 ret = false;
 291         }
 292         if (node->size > 0 && CLUSTER_INVALID(node->start_cluster))
 293         {
 294                 exfat_get_name(node, buffer);
 295                 exfat_error("'%s' points to invalid cluster %#x", buffer,
 296                                 node->start_cluster);
 297                 ret = false;
 298         }
 299
 300         /* Empty file or directory must be marked as non-contiguous. */
 301         if (node->size == 0 && node->is_contiguous)
 302         {
 303                 exfat_get_name(node, buffer);
 304                 exfat_error("'%s' is empty but marked as contiguous (%#hx)", buffer,
 305                                 node->attrib);
 306                 ret = false;
 307         }
 308
 309         /* Directory size must be aligned on at cluster boundary. */
 310         if ((node->attrib & EXFAT_ATTRIB_DIR) && node->size % cluster_size != 0)
 311         {
 312                 exfat_get_name(node, buffer);
 313                 exfat_error("'%s' directory size %"PRIu64" is not divisible by %d", buffer,
 314                                 node->size, cluster_size);
 315                 ret = false;
 316         }
 317
 318         return ret;
 319 }
 320
 321 static void decompress_upcase(uint16_t* output, const le16_t* source,
 322                 size_t size)
 323 {
 324         size_t si;
 325         size_t oi;
 326
 327         for (oi = 0; oi < EXFAT_UPCASE_CHARS; oi++)
 328                 output[oi] = oi;
 329
 330         for (si = 0, oi = 0; si < size && oi < EXFAT_UPCASE_CHARS; si++)
 331         {
 332                 uint16_t ch = le16_to_cpu(source[si]);
 333
 334                 if (ch == 0xffff && si + 1 < size)      /* indicates a run */
 335                         oi += le16_to_cpu(source[++si]);
 336                 else
 337                         output[oi++] = ch;
 338         }
 339 }
 340
 341 /*
 342  * Reads one entry in directory at position pointed by iterator and fills
 343  * node structure.
 344  */
 345 static int readdir(struct exfat* ef, const struct exfat_node* parent,
 346                 struct exfat_node** node, struct iterator* it)
 347 {
 348         int rc = -EIO;
 349         const struct exfat_entry* entry;
 350         const struct exfat_entry_meta1* meta1;
 351         const struct exfat_entry_meta2* meta2;
 352         const struct exfat_entry_name* file_name;
 353         const struct exfat_entry_upcase* upcase;
 354         const struct exfat_entry_bitmap* bitmap;
 355         const struct exfat_entry_label* label;
 356         uint8_t continuations = 0;
 357         le16_t* namep = NULL;
 358         uint16_t reference_checksum = 0;
 359         uint16_t actual_checksum = 0;
 360         uint64_t valid_size = 0;
 361         uint64_t upcase_size = 0;
 362         le16_t* upcase_comp = NULL;
 363
 364         *node = NULL;
 365
 366         for (;;)
 367         {
 368                 if (it->offset >= parent->size)
 369                 {
 370                         if (continuations != 0)
 371                         {
 372                                 exfat_error("expected %hhu continuations", continuations);
 373                                 goto error;
 374                         }
 375                         return -ENOENT; /* that's OK, means end of directory */
 376                 }
 377
 378                 entry = get_entry_ptr(ef, it);
 379                 switch (entry->type)
 380                 {
 381                 case EXFAT_ENTRY_FILE:
 382                         if (continuations != 0)
 383                         {
 384                                 exfat_error("expected %hhu continuations before new entry",
 385                                                 continuations);
 386                                 goto error;
 387                         }
 388                         meta1 = (const struct exfat_entry_meta1*) entry;
 389                         continuations = meta1->continuations;
 390                         /* each file entry must have at least 2 continuations:
 391                            info and name */
 392                         if (continuations < 2)
 393                         {
 394                                 exfat_error("too few continuations (%hhu)", continuations);
 395                                 goto error;
 396                         }
 397                         if (continuations > 1 +
 398                                         DIV_ROUND_UP(EXFAT_NAME_MAX, EXFAT_ENAME_MAX))
 399                         {
 400                                 exfat_error("too many continuations (%hhu)", continuations);
 401                                 goto error;
 402                         }
 403                         reference_checksum = le16_to_cpu(meta1->checksum);
 404                         actual_checksum = exfat_start_checksum(meta1);
 405                         *node = allocate_node();
 406                         if (*node == NULL)
 407                         {
 408                                 rc = -ENOMEM;
 409                                 goto error;
 410                         }
 411                         /* new node has zero reference counter */
 412                         (*node)->entry_cluster = it->cluster;
 413                         (*node)->entry_offset = it->offset;
 414                         init_node_meta1(*node, meta1);
 415                         namep = (*node)->name;
 416                         break;
 417
 418                 case EXFAT_ENTRY_FILE_INFO:
 419                         if (continuations < 2)
 420                         {
 421                                 exfat_error("unexpected continuation (%hhu)",
 422                                                 continuations);
 423                                 goto error;
 424                         }
 425                         meta2 = (const struct exfat_entry_meta2*) entry;
 426                         if (meta2->flags & ~(EXFAT_FLAG_ALWAYS1 | EXFAT_FLAG_CONTIGUOUS))
 427                         {
 428                                 exfat_error("unknown flags in meta2 (0x%hhx)", meta2->flags);
 429                                 goto error;
 430                         }
 431                         init_node_meta2(*node, meta2);
 432                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 433                         valid_size = le64_to_cpu(meta2->valid_size);
 434                         --continuations;
 435                         break;
 436
 437                 case EXFAT_ENTRY_FILE_NAME:
 438                         if (continuations == 0)
 439                         {
 440                                 exfat_error("unexpected continuation");
 441                                 goto error;
 442                         }
 443                         file_name = (const struct exfat_entry_name*) entry;
 444                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 445
 446                         memcpy(namep, file_name->name,
 447                                         MIN(EXFAT_ENAME_MAX,
 448                                                 ((*node)->name + EXFAT_NAME_MAX - namep)) *
 449                                         sizeof(le16_t));
 450                         namep += EXFAT_ENAME_MAX;
 451                         if (--continuations == 0)
 452                         {
 453                                 if (!check_node(*node, actual_checksum, reference_checksum,
 454                                                 valid_size, CLUSTER_SIZE(*ef->sb)))
 455                                         goto error;
 456                                 if (!fetch_next_entry(ef, parent, it))
 457                                         goto error;
 458                                 return 0; /* entry completed */
 459                         }
 460                         break;
 461
 462                 case EXFAT_ENTRY_UPCASE:
 463                         if (ef->upcase != NULL)
 464                                 break;
 465                         upcase = (const struct exfat_entry_upcase*) entry;
 466                         if (CLUSTER_INVALID(le32_to_cpu(upcase->start_cluster)))
 467                         {
 468                                 exfat_error("invalid cluster 0x%x in upcase table",
 469                                                 le32_to_cpu(upcase->start_cluster));
 470                                 goto error;
 471                         }
 472                         upcase_size = le64_to_cpu(upcase->size);
 473                         if (upcase_size == 0 ||
 474                                 upcase_size > EXFAT_UPCASE_CHARS * sizeof(uint16_t) ||
 475                                 upcase_size % sizeof(uint16_t) != 0)
 476                         {
 477                                 exfat_error("bad upcase table size (%"PRIu64" bytes)",
 478                                                 upcase_size);
 479                                 goto error;
 480                         }
 481                         upcase_comp = malloc(upcase_size);
 482                         if (upcase_comp == NULL)
 483                         {
 484                                 exfat_error("failed to allocate upcase table (%"PRIu64" bytes)",
 485                                                 upcase_size);
 486                                 rc = -ENOMEM;
 487                                 goto error;
 488                         }
 489
 490                         /* read compressed upcase table */
 491                         if (exfat_pread(ef->dev, upcase_comp, upcase_size,
 492                                         exfat_c2o(ef, le32_to_cpu(upcase->start_cluster))) < 0)
 493                         {
 494                                 free(upcase_comp);
 495                                 exfat_error("failed to read upper case table "
 496                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 497                                                 upcase_size,
 498                                                 le32_to_cpu(upcase->start_cluster));
 499                                 goto error;
 500                         }
 501
 502                         /* decompress upcase table */
 503                         ef->upcase = calloc(EXFAT_UPCASE_CHARS, sizeof(uint16_t));
 504                         if (ef->upcase == NULL)
 505                         {
 506                                 free(upcase_comp);
 507                                 exfat_error("failed to allocate decompressed upcase table");
 508                                 rc = -ENOMEM;
 509                                 goto error;
 510                         }
 511                         decompress_upcase(ef->upcase, upcase_comp,
 512                                         upcase_size / sizeof(uint16_t));
 513                         free(upcase_comp);
 514                         break;
 515
 516                 case EXFAT_ENTRY_BITMAP:
 517                         bitmap = (const struct exfat_entry_bitmap*) entry;
 518                         ef->cmap.start_cluster = le32_to_cpu(bitmap->start_cluster);
 519                         if (CLUSTER_INVALID(ef->cmap.start_cluster))
 520                         {
 521                                 exfat_error("invalid cluster 0x%x in clusters bitmap",
 522                                                 ef->cmap.start_cluster);
 523                                 goto error;
 524                         }
 525                         ef->cmap.size = le32_to_cpu(ef->sb->cluster_count) -
 526                                 EXFAT_FIRST_DATA_CLUSTER;
 527                         if (le64_to_cpu(bitmap->size) < DIV_ROUND_UP(ef->cmap.size, 8))
 528                         {
 529                                 exfat_error("invalid clusters bitmap size: %"PRIu64
 530                                                 " (expected at least %u)",
 531                                                 le64_to_cpu(bitmap->size),
 532                                                 DIV_ROUND_UP(ef->cmap.size, 8));
 533                                 goto error;
 534                         }
 535                         /* FIXME bitmap can be rather big, up to 512 MB */
 536                         ef->cmap.chunk_size = ef->cmap.size;
 537                         ef->cmap.chunk = malloc(BMAP_SIZE(ef->cmap.chunk_size));
 538                         if (ef->cmap.chunk == NULL)
 539                         {
 540                                 exfat_error("failed to allocate clusters bitmap chunk "
 541                                                 "(%"PRIu64" bytes)", le64_to_cpu(bitmap->size));
 542                                 rc = -ENOMEM;
 543                                 goto error;
 544                         }
 545
 546                         if (exfat_pread(ef->dev, ef->cmap.chunk,
 547                                         BMAP_SIZE(ef->cmap.chunk_size),
 548                                         exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
 549                         {
 550                                 exfat_error("failed to read clusters bitmap "
 551                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 552                                                 le64_to_cpu(bitmap->size), ef->cmap.start_cluster);
 553                                 goto error;
 554                         }
 555                         break;
 556
 557                 case EXFAT_ENTRY_LABEL:
 558                         label = (const struct exfat_entry_label*) entry;
 559                         if (label->length > EXFAT_ENAME_MAX)
 560                         {
 561                                 exfat_error("too long label (%hhu chars)", label->length);
 562                                 goto error;
 563                         }
 564                         if (utf16_to_utf8(ef->label, label->name,
 565                                                 sizeof(ef->label), EXFAT_ENAME_MAX) != 0)
 566                                 goto error;
 567                         break;
 568
 569                 default:
 570                         if (!(entry->type & EXFAT_ENTRY_VALID))
 571                                 break; /* deleted entry, ignore it */
 572                         if (!(entry->type & EXFAT_ENTRY_OPTIONAL))
 573                         {
 574                                 exfat_error("unknown entry type %#hhx", entry->type);
 575                                 goto error;
 576                         }
 577                         /* optional entry, warn and skip */
 578                         exfat_warn("unknown entry type %#hhx", entry->type);
 579                         if (continuations == 0)
 580                         {
 581                                 exfat_error("unexpected continuation");
 582                                 goto error;
 583                         }
 584                         --continuations;
 585                         break;
 586                 }
 587
 588                 if (!fetch_next_entry(ef, parent, it))
 589                         goto error;
 590         }
 591         /* we never reach here */
 592
 593 error:
 594         free(*node);
 595         *node = NULL;
 596         return rc;
 597 }
 598
 599 int exfat_cache_directory(struct exfat* ef, struct exfat_node* dir)
 600 {
 601         struct iterator it;
 602         int rc;
 603         struct exfat_node* node;
 604         struct exfat_node* current = NULL;
 605
 606         if (dir->is_cached)
 607                 return 0; /* already cached */
 608
 609         rc = opendir(ef, dir, &it);
 610         if (rc != 0)
 611                 return rc;
 612         while ((rc = readdir(ef, dir, &node, &it)) == 0)
 613         {
 614                 node->parent = dir;
 615                 if (current != NULL)
 616                 {
 617                         current->next = node;
 618                         node->prev = current;
 619                 }
 620                 else
 621                         dir->child = node;
 622
 623                 current = node;
 624         }
 625         closedir(&it);
 626
 627         if (rc != -ENOENT)
 628         {
 629                 /* rollback */
 630                 for (current = dir->child; current; current = node)
 631                 {
 632                         node = current->next;
 633                         free(current);
 634                 }
 635                 dir->child = NULL;
 636                 return rc;
 637         }
 638
 639         dir->is_cached = true;
 640         return 0;
 641 }
 642
 643 static void tree_attach(struct exfat_node* dir, struct exfat_node* node)
 644 {
 645         node->parent = dir;
 646         if (dir->child)
 647         {
 648                 dir->child->prev = node;
 649                 node->next = dir->child;
 650         }
 651         dir->child = node;
 652 }
 653
 654 static void tree_detach(struct exfat_node* node)
 655 {
 656         if (node->prev)
 657                 node->prev->next = node->next;
 658         else /* this is the first node in the list */
 659                 node->parent->child = node->next;
 660         if (node->next)
 661                 node->next->prev = node->prev;
 662         node->parent = NULL;
 663         node->prev = NULL;
 664         node->next = NULL;
 665 }
 666
 667 static void reset_cache(struct exfat* ef, struct exfat_node* node)
 668 {
 669         char buffer[EXFAT_UTF8_NAME_BUFFER_MAX];
 670
 671         while (node->child)
 672         {
 673                 struct exfat_node* p = node->child;
 674                 reset_cache(ef, p);
 675                 tree_detach(p);
 676                 free(p);
 677         }
 678         node->is_cached = false;
 679         if (node->references != 0)
 680         {
 681                 exfat_get_name(node, buffer);
 682                 exfat_warn("non-zero reference counter (%d) for '%s'",
 683                                 node->references, buffer);
 684         }
 685         if (node != ef->root && node->is_dirty)
 686         {
 687                 exfat_get_name(node, buffer);
 688                 exfat_bug("node '%s' is dirty", buffer);
 689         }
 690         while (node->references)
 691                 exfat_put_node(ef, node);
 692 }
 693
 694 void exfat_reset_cache(struct exfat* ef)
 695 {
 696         reset_cache(ef, ef->root);
 697 }
 698
 699 static bool next_entry(struct exfat* ef, const struct exfat_node* parent,
 700                 cluster_t* cluster, off_t* offset)
 701 {
 702         *offset += sizeof(struct exfat_entry);
 703         if (*offset % CLUSTER_SIZE(*ef->sb) == 0)
 704         {
 705                 *cluster = exfat_next_cluster(ef, parent, *cluster);
 706                 if (CLUSTER_INVALID(*cluster))
 707                 {
 708                         exfat_error("invalid cluster %#x while getting next entry",
 709                                         *cluster);
 710                         return false;
 711                 }
 712         }
 713         return true;
 714 }
 715
 716 int exfat_flush_node(struct exfat* ef, struct exfat_node* node)
 717 {
 718         cluster_t cluster;
 719         off_t offset;
 720         off_t meta1_offset, meta2_offset;
 721         struct exfat_entry_meta1 meta1;
 722         struct exfat_entry_meta2 meta2;
 723
 724         if (!node->is_dirty)
 725                 return 0; /* no need to flush */
 726
 727         if (ef->ro)
 728                 exfat_bug("unable to flush node to read-only FS");
 729
 730         if (node->parent == NULL)
 731                 return 0; /* do not flush unlinked node */
 732
 733         cluster = node->entry_cluster;
 734         offset = node->entry_offset;
 735         meta1_offset = co2o(ef, cluster, offset);
 736         if (!next_entry(ef, node->parent, &cluster, &offset))
 737                 return -EIO;
 738         meta2_offset = co2o(ef, cluster, offset);
 739
 740         if (exfat_pread(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 741         {
 742                 exfat_error("failed to read meta1 entry on flush");
 743                 return -EIO;
 744         }
 745         if (meta1.type != EXFAT_ENTRY_FILE)
 746                 exfat_bug("invalid type of meta1: 0x%hhx", meta1.type);
 747         meta1.attrib = cpu_to_le16(node->attrib);
 748         exfat_unix2exfat(node->mtime, &meta1.mdate, &meta1.mtime, &meta1.mtime_cs);
 749         exfat_unix2exfat(node->atime, &meta1.adate, &meta1.atime, NULL);
 750
 751         if (exfat_pread(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 752         {
 753                 exfat_error("failed to read meta2 entry on flush");
 754                 return -EIO;
 755         }
 756         if (meta2.type != EXFAT_ENTRY_FILE_INFO)
 757                 exfat_bug("invalid type of meta2: 0x%hhx", meta2.type);
 758         meta2.size = meta2.valid_size = cpu_to_le64(node->size);
 759         meta2.start_cluster = cpu_to_le32(node->start_cluster);
 760         meta2.flags = EXFAT_FLAG_ALWAYS1;
 761         /* empty files must not be marked as contiguous */
 762         if (node->size != 0 && node->is_contiguous)
 763                 meta2.flags |= EXFAT_FLAG_CONTIGUOUS;
 764         /* name hash remains unchanged, no need to recalculate it */
 765
 766         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 767
 768         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 769         {
 770                 exfat_error("failed to write meta1 entry on flush");
 771                 return -EIO;
 772         }
 773         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 774         {
 775                 exfat_error("failed to write meta2 entry on flush");
 776                 return -EIO;
 777         }
 778
 779         node->is_dirty = false;
 780         return exfat_flush(ef);
 781 }
 782
 783 static bool erase_entry(struct exfat* ef, struct exfat_node* node)
 784 {
 785         cluster_t cluster = node->entry_cluster;
 786         off_t offset = node->entry_offset;
 787         int name_entries = DIV_ROUND_UP(utf16_length(node->name), EXFAT_ENAME_MAX);
 788         uint8_t entry_type;
 789
 790         entry_type = EXFAT_ENTRY_FILE & ~EXFAT_ENTRY_VALID;
 791         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 792         {
 793                 exfat_error("failed to erase meta1 entry");
 794                 return false;
 795         }
 796
 797         if (!next_entry(ef, node->parent, &cluster, &offset))
 798                 return false;
 799         entry_type = EXFAT_ENTRY_FILE_INFO & ~EXFAT_ENTRY_VALID;
 800         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 801         {
 802                 exfat_error("failed to erase meta2 entry");
 803                 return false;
 804         }
 805
 806         while (name_entries--)
 807         {
 808                 if (!next_entry(ef, node->parent, &cluster, &offset))
 809                         return false;
 810                 entry_type = EXFAT_ENTRY_FILE_NAME & ~EXFAT_ENTRY_VALID;
 811                 if (exfat_pwrite(ef->dev, &entry_type, 1,
 812                                 co2o(ef, cluster, offset)) < 0)
 813                 {
 814                         exfat_error("failed to erase name entry");
 815                         return false;
 816                 }
 817         }
 818         return true;
 819 }
 820
 821 static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
 822                 off_t deleted_offset)
 823 {
 824         const struct exfat_node* node;
 825         const struct exfat_node* last_node;
 826         uint64_t entries = 0;
 827         uint64_t new_size;
 828
 829         if (!(dir->attrib & EXFAT_ATTRIB_DIR))
 830                 exfat_bug("attempted to shrink a file");
 831         if (!dir->is_cached)
 832                 exfat_bug("attempted to shrink uncached directory");
 833
 834         for (last_node = node = dir->child; node; node = node->next)
 835         {
 836                 if (deleted_offset < node->entry_offset)
 837                 {
 838                         /* there are other entries after the removed one, no way to shrink
 839                            this directory */
 840                         return 0;
 841                 }
 842                 if (last_node->entry_offset < node->entry_offset)
 843                         last_node = node;
 844         }
 845
 846         if (last_node)
 847         {
 848                 /* offset of the last entry */
 849                 entries += last_node->entry_offset / sizeof(struct exfat_entry);
 850                 /* two subentries with meta info */
 851                 entries += 2;
 852                 /* subentries with file name */
 853                 entries += DIV_ROUND_UP(utf16_length(last_node->name),
 854                                 EXFAT_ENAME_MAX);
 855         }
 856
 857         new_size = DIV_ROUND_UP(entries * sizeof(struct exfat_entry),
 858                                  CLUSTER_SIZE(*ef->sb)) * CLUSTER_SIZE(*ef->sb);
 859         if (new_size == 0) /* directory always has at least 1 cluster */
 860                 new_size = CLUSTER_SIZE(*ef->sb);
 861         if (new_size == dir->size)
 862                 return 0;
 863         return exfat_truncate(ef, dir, new_size, true);
 864 }
 865
 866 static int delete(struct exfat* ef, struct exfat_node* node)
 867 {
 868         struct exfat_node* parent = node->parent;
 869         off_t deleted_offset = node->entry_offset;
 870         int rc;
 871
 872         exfat_get_node(parent);
 873         if (!erase_entry(ef, node))
 874         {
 875                 exfat_put_node(ef, parent);
 876                 return -EIO;
 877         }
 878         exfat_update_mtime(parent);
 879         tree_detach(node);
 880         rc = shrink_directory(ef, parent, deleted_offset);
 881         node->is_unlinked = true;
 882         if (rc != 0)
 883         {
 884                 exfat_flush_node(ef, parent);
 885                 exfat_put_node(ef, parent);
 886                 return rc;
 887         }
 888         rc = exfat_flush_node(ef, parent);
 889         exfat_put_node(ef, parent);
 890         return rc;
 891 }
 892
 893 int exfat_unlink(struct exfat* ef, struct exfat_node* node)
 894 {
 895         if (node->attrib & EXFAT_ATTRIB_DIR)
 896                 return -EISDIR;
 897         return delete(ef, node);
 898 }
 899
 900 int exfat_rmdir(struct exfat* ef, struct exfat_node* node)
 901 {
 902         int rc;
 903
 904         if (!(node->attrib & EXFAT_ATTRIB_DIR))
 905                 return -ENOTDIR;
 906         /* check that directory is empty */
 907         rc = exfat_cache_directory(ef, node);
 908         if (rc != 0)
 909                 return rc;
 910         if (node->child)
 911                 return -ENOTEMPTY;
 912         return delete(ef, node);
 913 }
 914
 915 static int grow_directory(struct exfat* ef, struct exfat_node* dir,
 916                 uint64_t asize, uint32_t difference)
 917 {
 918         return exfat_truncate(ef, dir,
 919                         DIV_ROUND_UP(asize + difference, CLUSTER_SIZE(*ef->sb))
 920                                 * CLUSTER_SIZE(*ef->sb), true);
 921 }
 922
 923 static int find_slot(struct exfat* ef, struct exfat_node* dir,
 924                 cluster_t* cluster, off_t* offset, int subentries)
 925 {
 926         struct iterator it;
 927         int rc;
 928         const struct exfat_entry* entry;
 929         int contiguous = 0;
 930
 931         rc = opendir(ef, dir, &it);
 932         if (rc != 0)
 933                 return rc;
 934         for (;;)
 935         {
 936                 if (contiguous == 0)
 937                 {
 938                         *cluster = it.cluster;
 939                         *offset = it.offset;
 940                 }
 941                 entry = get_entry_ptr(ef, &it);
 942                 if (entry->type & EXFAT_ENTRY_VALID)
 943                         contiguous = 0;
 944                 else
 945                         contiguous++;
 946                 if (contiguous == subentries)
 947                         break;  /* suitable slot is found */
 948                 if (it.offset + sizeof(struct exfat_entry) >= dir->size)
 949                 {
 950                         rc = grow_directory(ef, dir, dir->size,
 951                                         (subentries - contiguous) * sizeof(struct exfat_entry));
 952                         if (rc != 0)
 953                         {
 954                                 closedir(&it);
 955                                 return rc;
 956                         }
 957                 }
 958                 if (!fetch_next_entry(ef, dir, &it))
 959                 {
 960                         closedir(&it);
 961                         return -EIO;
 962                 }
 963         }
 964         closedir(&it);
 965         return 0;
 966 }
 967
 968 static int commit_entry(struct exfat* ef, struct exfat_node* dir,
 969                 const le16_t* name, cluster_t cluster, off_t offset, uint16_t attrib)
 970 {
 971         struct exfat_node* node;
 972         const size_t name_length = utf16_length(name);
 973         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
 974         struct exfat_entry entries[2 + name_entries];
 975         struct exfat_entry_meta1* meta1 = (struct exfat_entry_meta1*) &entries[0];
 976         struct exfat_entry_meta2* meta2 = (struct exfat_entry_meta2*) &entries[1];
 977         int i;
 978         int rc;
 979
 980         memset(entries, 0, sizeof(struct exfat_entry[2]));
 981
 982         meta1->type = EXFAT_ENTRY_FILE;
 983         meta1->continuations = 1 + name_entries;
 984         meta1->attrib = cpu_to_le16(attrib);
 985         exfat_unix2exfat(time(NULL), &meta1->crdate, &meta1->crtime,
 986                         &meta1->crtime_cs);
 987         meta1->adate = meta1->mdate = meta1->crdate;
 988         meta1->atime = meta1->mtime = meta1->crtime;
 989         meta1->mtime_cs = meta1->crtime_cs; /* there is no atime_cs */
 990
 991         meta2->type = EXFAT_ENTRY_FILE_INFO;
 992         meta2->flags = EXFAT_FLAG_ALWAYS1;
 993         meta2->name_length = name_length;
 994         meta2->name_hash = exfat_calc_name_hash(ef, name, name_length);
 995         meta2->start_cluster = cpu_to_le32(EXFAT_CLUSTER_FREE);
 996
 997         meta1->checksum = exfat_calc_checksum(meta1, meta2, name);
 998
 999         for (i = 0; i < name_entries; i++)
1000         {
1001                 struct exfat_entry_name* name_entry;
1002
1003                 name_entry = (struct exfat_entry_name*) &entries[2 + i];
1004                 name_entry->type = EXFAT_ENTRY_FILE_NAME;
1005                 name_entry->__unknown = 0;
1006                 memcpy(name_entry->name, name + i * EXFAT_ENAME_MAX,
1007                                 EXFAT_ENAME_MAX * sizeof(le16_t));
1008         }
1009
1010         rc = write_entries(ef, dir, entries, 2 + name_entries, offset);
1011         if (rc != 0)
1012                 return rc;
1013
1014         node = allocate_node();
1015         if (node == NULL)
1016                 return -ENOMEM;
1017         node->entry_cluster = cluster;
1018         node->entry_offset = offset;
1019         memcpy(node->name, name, name_length * sizeof(le16_t));
1020         init_node_meta1(node, meta1);
1021         init_node_meta2(node, meta2);
1022
1023         tree_attach(dir, node);
1024         return 0;
1025 }
1026
1027 static int create(struct exfat* ef, const char* path, uint16_t attrib)
1028 {
1029         struct exfat_node* dir;
1030         struct exfat_node* existing;
1031         cluster_t cluster = EXFAT_CLUSTER_BAD;
1032         off_t offset = -1;
1033         le16_t name[EXFAT_NAME_MAX + 1];
1034         int rc;
1035
1036         rc = exfat_split(ef, &dir, &existing, name, path);
1037         if (rc != 0)
1038                 return rc;
1039         if (existing != NULL)
1040         {
1041                 exfat_put_node(ef, existing);
1042                 exfat_put_node(ef, dir);
1043                 return -EEXIST;
1044         }
1045
1046         rc = find_slot(ef, dir, &cluster, &offset,
1047                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1048         if (rc != 0)
1049         {
1050                 exfat_put_node(ef, dir);
1051                 return rc;
1052         }
1053         rc = commit_entry(ef, dir, name, cluster, offset, attrib);
1054         if (rc != 0)
1055         {
1056                 exfat_put_node(ef, dir);
1057                 return rc;
1058         }
1059         exfat_update_mtime(dir);
1060         rc = exfat_flush_node(ef, dir);
1061         exfat_put_node(ef, dir);
1062         return rc;
1063 }
1064
1065 int exfat_mknod(struct exfat* ef, const char* path)
1066 {
1067         return create(ef, path, EXFAT_ATTRIB_ARCH);
1068 }
1069
1070 int exfat_mkdir(struct exfat* ef, const char* path)
1071 {
1072         int rc;
1073         struct exfat_node* node;
1074
1075         rc = create(ef, path, EXFAT_ATTRIB_DIR);
1076         if (rc != 0)
1077                 return rc;
1078         rc = exfat_lookup(ef, &node, path);
1079         if (rc != 0)
1080                 return 0;
1081         /* directories always have at least one cluster */
1082         rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
1083         if (rc != 0)
1084         {
1085                 delete(ef, node);
1086                 exfat_put_node(ef, node);
1087                 return rc;
1088         }
1089         rc = exfat_flush_node(ef, node);
1090         if (rc != 0)
1091         {
1092                 delete(ef, node);
1093                 exfat_put_node(ef, node);
1094                 return rc;
1095         }
1096         exfat_put_node(ef, node);
1097         return 0;
1098 }
1099
1100 static int rename_entry(struct exfat* ef, struct exfat_node* dir,
1101                 struct exfat_node* node, const le16_t* name, cluster_t new_cluster,
1102                 off_t new_offset)
1103 {
1104         struct exfat_entry_meta1 meta1;
1105         struct exfat_entry_meta2 meta2;
1106         cluster_t old_cluster = node->entry_cluster;
1107         off_t old_offset = node->entry_offset;
1108         const size_t name_length = utf16_length(name);
1109         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
1110         int i;
1111
1112         if (exfat_pread(ef->dev, &meta1, sizeof(meta1),
1113                         co2o(ef, old_cluster, old_offset)) < 0)
1114         {
1115                 exfat_error("failed to read meta1 entry on rename");
1116                 return -EIO;
1117         }
1118         if (!next_entry(ef, node->parent, &old_cluster, &old_offset))
1119                 return -EIO;
1120         if (exfat_pread(ef->dev, &meta2, sizeof(meta2),
1121                         co2o(ef, old_cluster, old_offset)) < 0)
1122         {
1123                 exfat_error("failed to read meta2 entry on rename");
1124                 return -EIO;
1125         }
1126         meta1.continuations = 1 + name_entries;
1127         meta2.name_hash = exfat_calc_name_hash(ef, name, name_length);
1128         meta2.name_length = name_length;
1129         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, name);
1130
1131         if (!erase_entry(ef, node))
1132                 return -EIO;
1133
1134         node->entry_cluster = new_cluster;
1135         node->entry_offset = new_offset;
1136
1137         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
1138                         co2o(ef, new_cluster, new_offset)) < 0)
1139         {
1140                 exfat_error("failed to write meta1 entry on rename");
1141                 return -EIO;
1142         }
1143         if (!next_entry(ef, dir, &new_cluster, &new_offset))
1144                 return -EIO;
1145         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
1146                         co2o(ef, new_cluster, new_offset)) < 0)
1147         {
1148                 exfat_error("failed to write meta2 entry on rename");
1149                 return -EIO;
1150         }
1151
1152         for (i = 0; i < name_entries; i++)
1153         {
1154                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
1155                 memcpy(name_entry.name, name + i * EXFAT_ENAME_MAX,
1156                                 EXFAT_ENAME_MAX * sizeof(le16_t));
1157                 if (!next_entry(ef, dir, &new_cluster, &new_offset))
1158                         return -EIO;
1159                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
1160                                 co2o(ef, new_cluster, new_offset)) < 0)
1161                 {
1162                         exfat_error("failed to write name entry on rename");
1163                         return -EIO;
1164                 }
1165         }
1166
1167         memcpy(node->name, name, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
1168         tree_detach(node);
1169         tree_attach(dir, node);
1170         return 0;
1171 }
1172
1173 int exfat_rename(struct exfat* ef, const char* old_path, const char* new_path)
1174 {
1175         struct exfat_node* node;
1176         struct exfat_node* existing;
1177         struct exfat_node* dir;
1178         cluster_t cluster = EXFAT_CLUSTER_BAD;
1179         off_t offset = -1;
1180         le16_t name[EXFAT_NAME_MAX + 1];
1181         int rc;
1182
1183         rc = exfat_lookup(ef, &node, old_path);
1184         if (rc != 0)
1185                 return rc;
1186
1187         rc = exfat_split(ef, &dir, &existing, name, new_path);
1188         if (rc != 0)
1189         {
1190                 exfat_put_node(ef, node);
1191                 return rc;
1192         }
1193
1194         /* check that target is not a subdirectory of the source */
1195         if (node->attrib & EXFAT_ATTRIB_DIR)
1196         {
1197                 struct exfat_node* p;
1198
1199                 for (p = dir; p; p = p->parent)
1200                         if (node == p)
1201                         {
1202                                 if (existing != NULL)
1203                                         exfat_put_node(ef, existing);
1204                                 exfat_put_node(ef, dir);
1205                                 exfat_put_node(ef, node);
1206                                 return -EINVAL;
1207                         }
1208         }
1209
1210         if (existing != NULL)
1211         {
1212                 /* remove target if it's not the same node as source */
1213                 if (existing != node)
1214                 {
1215                         if (existing->attrib & EXFAT_ATTRIB_DIR)
1216                         {
1217                                 if (node->attrib & EXFAT_ATTRIB_DIR)
1218                                         rc = exfat_rmdir(ef, existing);
1219                                 else
1220                                         rc = -ENOTDIR;
1221                         }
1222                         else
1223                         {
1224                                 if (!(node->attrib & EXFAT_ATTRIB_DIR))
1225                                         rc = exfat_unlink(ef, existing);
1226                                 else
1227                                         rc = -EISDIR;
1228                         }
1229                         exfat_put_node(ef, existing);
1230                         if (rc != 0)
1231                         {
1232                                 /* free clusters even if something went wrong; overwise they
1233                                    will be just lost */
1234                                 exfat_cleanup_node(ef, existing);
1235                                 exfat_put_node(ef, dir);
1236                                 exfat_put_node(ef, node);
1237                                 return rc;
1238                         }
1239                         rc = exfat_cleanup_node(ef, existing);
1240                         if (rc != 0)
1241                         {
1242                                 exfat_put_node(ef, dir);
1243                                 exfat_put_node(ef, node);
1244                                 return rc;
1245                         }
1246                 }
1247                 else
1248                         exfat_put_node(ef, existing);
1249         }
1250
1251         rc = find_slot(ef, dir, &cluster, &offset,
1252                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1253         if (rc != 0)
1254         {
1255                 exfat_put_node(ef, dir);
1256                 exfat_put_node(ef, node);
1257                 return rc;
1258         }
1259         rc = rename_entry(ef, dir, node, name, cluster, offset);
1260         exfat_put_node(ef, dir);
1261         exfat_put_node(ef, node);
1262         return rc;
1263 }
1264
1265 void exfat_utimes(struct exfat_node* node, const struct timespec tv[2])
1266 {
1267         node->atime = tv[0].tv_sec;
1268         node->mtime = tv[1].tv_sec;
1269         node->is_dirty = true;
1270 }
1271
1272 void exfat_update_atime(struct exfat_node* node)
1273 {
1274         node->atime = time(NULL);
1275         node->is_dirty = true;
1276 }
1277
1278 void exfat_update_mtime(struct exfat_node* node)
1279 {
1280         node->mtime = time(NULL);
1281         node->is_dirty = true;
1282 }
1283
1284 const char* exfat_get_label(struct exfat* ef)
1285 {
1286         return ef->label;
1287 }
1288
1289 static int find_label(struct exfat* ef, off_t* offset)
1290 {
1291         struct exfat_entry entry;
1292         int rc;
1293
1294         for (*offset = 0; ; *offset += sizeof(entry))
1295         {
1296                 rc = read_entries(ef, ef->root, &entry, 1, *offset);
1297                 if (rc != 0)
1298                         return rc;
1299
1300                 if (entry.type == EXFAT_ENTRY_LABEL)
1301                         return 0;
1302         }
1303 }
1304
1305 int exfat_set_label(struct exfat* ef, const char* label)
1306 {
1307         le16_t label_utf16[EXFAT_ENAME_MAX + 1];
1308         int rc;
1309         cluster_t cluster;
1310         off_t offset;
1311         struct exfat_entry_label entry;
1312
1313         memset(label_utf16, 0, sizeof(label_utf16));
1314         rc = utf8_to_utf16(label_utf16, label, EXFAT_ENAME_MAX + 1, strlen(label));
1315         if (rc != 0)
1316                 return rc;
1317
1318         rc = find_label(ef, &offset);
1319         if (rc == -ENOENT)
1320                 rc = find_slot(ef, ef->root, &cluster, &offset, 1);
1321         if (rc != 0)
1322                 return rc;
1323
1324         entry.type = EXFAT_ENTRY_LABEL;
1325         entry.length = utf16_length(label_utf16);
1326         memcpy(entry.name, label_utf16, sizeof(entry.name));
1327         if (entry.length == 0)
1328                 entry.type ^= EXFAT_ENTRY_VALID;
1329
1330         rc = write_entries(ef, ef->root, (struct exfat_entry*) &entry, 1, offset);
1331         if (rc != 0)
1332                 return rc;
1333
1334         strcpy(ef->label, label);
1335         return 0;
1336 }