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, int cluster_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         /* Empty file or directory must be marked as non-contiguous. */
 262         if (node->size == 0 && (node->flags & EXFAT_ATTRIB_CONTIGUOUS))
 263         {
 264                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 265                 exfat_error("'%s' is empty but marked as contiguous (%#x)", buffer,
 266                                 node->flags);
 267                 ret = false;
 268         }
 269
 270         /* Directory size must be aligned on at cluster boundary. */
 271         if ((node->flags & EXFAT_ATTRIB_DIR) && node->size % cluster_size != 0)
 272         {
 273                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 274                 exfat_error("'%s' directory size %"PRIu64" is not divisible by %d", buffer,
 275                                 node->size, cluster_size);
 276                 ret = false;
 277         }
 278
 279         return ret;
 280 }
 281
 282 static void decompress_upcase(uint16_t* output, const le16_t* source,
 283                 size_t size)
 284 {
 285         size_t si;
 286         size_t oi;
 287
 288         for (oi = 0; oi < EXFAT_UPCASE_CHARS; oi++)
 289                 output[oi] = oi;
 290
 291         for (si = 0, oi = 0; si < size && oi < EXFAT_UPCASE_CHARS; si++)
 292         {
 293                 uint16_t ch = le16_to_cpu(source[si]);
 294
 295                 if (ch == 0xffff && si + 1 < size)      /* indicates a run */
 296                         oi += le16_to_cpu(source[++si]);
 297                 else
 298                         output[oi++] = ch;
 299         }
 300 }
 301
 302 /*
 303  * Reads one entry in directory at position pointed by iterator and fills
 304  * node structure.
 305  */
 306 static int readdir(struct exfat* ef, const struct exfat_node* parent,
 307                 struct exfat_node** node, struct iterator* it)
 308 {
 309         int rc = -EIO;
 310         const struct exfat_entry* entry;
 311         const struct exfat_entry_meta1* meta1;
 312         const struct exfat_entry_meta2* meta2;
 313         const struct exfat_entry_name* file_name;
 314         const struct exfat_entry_upcase* upcase;
 315         const struct exfat_entry_bitmap* bitmap;
 316         const struct exfat_entry_label* label;
 317         uint8_t continuations = 0;
 318         le16_t* namep = NULL;
 319         uint16_t reference_checksum = 0;
 320         uint16_t actual_checksum = 0;
 321         uint64_t valid_size = 0;
 322         uint64_t upcase_size = 0;
 323         le16_t* upcase_comp = NULL;
 324
 325         *node = NULL;
 326
 327         for (;;)
 328         {
 329                 if (it->offset >= parent->size)
 330                 {
 331                         if (continuations != 0)
 332                         {
 333                                 exfat_error("expected %hhu continuations", continuations);
 334                                 goto error;
 335                         }
 336                         return -ENOENT; /* that's OK, means end of directory */
 337                 }
 338
 339                 entry = get_entry_ptr(ef, it);
 340                 switch (entry->type)
 341                 {
 342                 case EXFAT_ENTRY_FILE:
 343                         if (continuations != 0)
 344                         {
 345                                 exfat_error("expected %hhu continuations before new entry",
 346                                                 continuations);
 347                                 goto error;
 348                         }
 349                         meta1 = (const struct exfat_entry_meta1*) entry;
 350                         continuations = meta1->continuations;
 351                         /* each file entry must have at least 2 continuations:
 352                            info and name */
 353                         if (continuations < 2)
 354                         {
 355                                 exfat_error("too few continuations (%hhu)", continuations);
 356                                 goto error;
 357                         }
 358                         if (continuations > 1 +
 359                                         DIV_ROUND_UP(EXFAT_NAME_MAX, EXFAT_ENAME_MAX))
 360                         {
 361                                 exfat_error("too many continuations (%hhu)", continuations);
 362                                 goto error;
 363                         }
 364                         reference_checksum = le16_to_cpu(meta1->checksum);
 365                         actual_checksum = exfat_start_checksum(meta1);
 366                         *node = allocate_node();
 367                         if (*node == NULL)
 368                         {
 369                                 rc = -ENOMEM;
 370                                 goto error;
 371                         }
 372                         /* new node has zero reference counter */
 373                         (*node)->entry_cluster = it->cluster;
 374                         (*node)->entry_offset = it->offset;
 375                         init_node_meta1(*node, meta1);
 376                         namep = (*node)->name;
 377                         break;
 378
 379                 case EXFAT_ENTRY_FILE_INFO:
 380                         if (continuations < 2)
 381                         {
 382                                 exfat_error("unexpected continuation (%hhu)",
 383                                                 continuations);
 384                                 goto error;
 385                         }
 386                         meta2 = (const struct exfat_entry_meta2*) entry;
 387                         if (meta2->flags & ~(EXFAT_FLAG_ALWAYS1 | EXFAT_FLAG_CONTIGUOUS))
 388                         {
 389                                 exfat_error("unknown flags in meta2 (0x%hhx)", meta2->flags);
 390                                 goto error;
 391                         }
 392                         init_node_meta2(*node, meta2);
 393                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 394                         valid_size = le64_to_cpu(meta2->valid_size);
 395                         --continuations;
 396                         break;
 397
 398                 case EXFAT_ENTRY_FILE_NAME:
 399                         if (continuations == 0)
 400                         {
 401                                 exfat_error("unexpected continuation");
 402                                 goto error;
 403                         }
 404                         file_name = (const struct exfat_entry_name*) entry;
 405                         actual_checksum = exfat_add_checksum(entry, actual_checksum);
 406
 407                         memcpy(namep, file_name->name,
 408                                         MIN(EXFAT_ENAME_MAX,
 409                                                 ((*node)->name + EXFAT_NAME_MAX - namep)) *
 410                                         sizeof(le16_t));
 411                         namep += EXFAT_ENAME_MAX;
 412                         if (--continuations == 0)
 413                         {
 414                                 if (!check_node(*node, actual_checksum, reference_checksum,
 415                                                 valid_size, CLUSTER_SIZE(*ef->sb)))
 416                                         goto error;
 417                                 if (!fetch_next_entry(ef, parent, it))
 418                                         goto error;
 419                                 return 0; /* entry completed */
 420                         }
 421                         break;
 422
 423                 case EXFAT_ENTRY_UPCASE:
 424                         if (ef->upcase != NULL)
 425                                 break;
 426                         upcase = (const struct exfat_entry_upcase*) entry;
 427                         if (CLUSTER_INVALID(le32_to_cpu(upcase->start_cluster)))
 428                         {
 429                                 exfat_error("invalid cluster 0x%x in upcase table",
 430                                                 le32_to_cpu(upcase->start_cluster));
 431                                 goto error;
 432                         }
 433                         upcase_size = le64_to_cpu(upcase->size);
 434                         if (upcase_size == 0 ||
 435                                 upcase_size > EXFAT_UPCASE_CHARS * sizeof(uint16_t) ||
 436                                 upcase_size % sizeof(uint16_t) != 0)
 437                         {
 438                                 exfat_error("bad upcase table size (%"PRIu64" bytes)",
 439                                                 upcase_size);
 440                                 goto error;
 441                         }
 442                         upcase_comp = malloc(upcase_size);
 443                         if (upcase_comp == NULL)
 444                         {
 445                                 exfat_error("failed to allocate upcase table (%"PRIu64" bytes)",
 446                                                 upcase_size);
 447                                 rc = -ENOMEM;
 448                                 goto error;
 449                         }
 450
 451                         /* read compressed upcase table */
 452                         if (exfat_pread(ef->dev, upcase_comp, upcase_size,
 453                                         exfat_c2o(ef, le32_to_cpu(upcase->start_cluster))) < 0)
 454                         {
 455                                 free(upcase_comp);
 456                                 exfat_error("failed to read upper case table "
 457                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 458                                                 upcase_size,
 459                                                 le32_to_cpu(upcase->start_cluster));
 460                                 goto error;
 461                         }
 462
 463                         /* decompress upcase table */
 464                         ef->upcase = calloc(EXFAT_UPCASE_CHARS, sizeof(uint16_t));
 465                         if (ef->upcase == NULL)
 466                         {
 467                                 free(upcase_comp);
 468                                 exfat_error("failed to allocate decompressed upcase table");
 469                                 rc = -ENOMEM;
 470                                 goto error;
 471                         }
 472                         decompress_upcase(ef->upcase, upcase_comp,
 473                                         upcase_size / sizeof(uint16_t));
 474                         free(upcase_comp);
 475                         break;
 476
 477                 case EXFAT_ENTRY_BITMAP:
 478                         bitmap = (const struct exfat_entry_bitmap*) entry;
 479                         ef->cmap.start_cluster = le32_to_cpu(bitmap->start_cluster);
 480                         if (CLUSTER_INVALID(ef->cmap.start_cluster))
 481                         {
 482                                 exfat_error("invalid cluster 0x%x in clusters bitmap",
 483                                                 ef->cmap.start_cluster);
 484                                 goto error;
 485                         }
 486                         ef->cmap.size = le32_to_cpu(ef->sb->cluster_count) -
 487                                 EXFAT_FIRST_DATA_CLUSTER;
 488                         if (le64_to_cpu(bitmap->size) < DIV_ROUND_UP(ef->cmap.size, 8))
 489                         {
 490                                 exfat_error("invalid clusters bitmap size: %"PRIu64
 491                                                 " (expected at least %u)",
 492                                                 le64_to_cpu(bitmap->size),
 493                                                 DIV_ROUND_UP(ef->cmap.size, 8));
 494                                 goto error;
 495                         }
 496                         /* FIXME bitmap can be rather big, up to 512 MB */
 497                         ef->cmap.chunk_size = ef->cmap.size;
 498                         ef->cmap.chunk = malloc(BMAP_SIZE(ef->cmap.chunk_size));
 499                         if (ef->cmap.chunk == NULL)
 500                         {
 501                                 exfat_error("failed to allocate clusters bitmap chunk "
 502                                                 "(%"PRIu64" bytes)", le64_to_cpu(bitmap->size));
 503                                 rc = -ENOMEM;
 504                                 goto error;
 505                         }
 506
 507                         if (exfat_pread(ef->dev, ef->cmap.chunk,
 508                                         BMAP_SIZE(ef->cmap.chunk_size),
 509                                         exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
 510                         {
 511                                 exfat_error("failed to read clusters bitmap "
 512                                                 "(%"PRIu64" bytes starting at cluster %#x)",
 513                                                 le64_to_cpu(bitmap->size), ef->cmap.start_cluster);
 514                                 goto error;
 515                         }
 516                         break;
 517
 518                 case EXFAT_ENTRY_LABEL:
 519                         label = (const struct exfat_entry_label*) entry;
 520                         if (label->length > EXFAT_ENAME_MAX)
 521                         {
 522                                 exfat_error("too long label (%hhu chars)", label->length);
 523                                 goto error;
 524                         }
 525                         if (utf16_to_utf8(ef->label, label->name,
 526                                                 sizeof(ef->label) - 1, EXFAT_ENAME_MAX) != 0)
 527                                 goto error;
 528                         break;
 529
 530                 default:
 531                         if (!(entry->type & EXFAT_ENTRY_VALID))
 532                                 break; /* deleted entry, ignore it */
 533                         if (!(entry->type & EXFAT_ENTRY_OPTIONAL))
 534                         {
 535                                 exfat_error("unknown entry type %#hhx", entry->type);
 536                                 goto error;
 537                         }
 538                         /* optional entry, warn and skip */
 539                         exfat_warn("unknown entry type %#hhx", entry->type);
 540                         if (continuations == 0)
 541                         {
 542                                 exfat_error("unexpected continuation");
 543                                 goto error;
 544                         }
 545                         --continuations;
 546                         break;
 547                 }
 548
 549                 if (!fetch_next_entry(ef, parent, it))
 550                         goto error;
 551         }
 552         /* we never reach here */
 553
 554 error:
 555         free(*node);
 556         *node = NULL;
 557         return rc;
 558 }
 559
 560 int exfat_cache_directory(struct exfat* ef, struct exfat_node* dir)
 561 {
 562         struct iterator it;
 563         int rc;
 564         struct exfat_node* node;
 565         struct exfat_node* current = NULL;
 566
 567         if (dir->flags & EXFAT_ATTRIB_CACHED)
 568                 return 0; /* already cached */
 569
 570         rc = opendir(ef, dir, &it);
 571         if (rc != 0)
 572                 return rc;
 573         while ((rc = readdir(ef, dir, &node, &it)) == 0)
 574         {
 575                 node->parent = dir;
 576                 if (current != NULL)
 577                 {
 578                         current->next = node;
 579                         node->prev = current;
 580                 }
 581                 else
 582                         dir->child = node;
 583
 584                 current = node;
 585         }
 586         closedir(&it);
 587
 588         if (rc != -ENOENT)
 589         {
 590                 /* rollback */
 591                 for (current = dir->child; current; current = node)
 592                 {
 593                         node = current->next;
 594                         free(current);
 595                 }
 596                 dir->child = NULL;
 597                 return rc;
 598         }
 599
 600         dir->flags |= EXFAT_ATTRIB_CACHED;
 601         return 0;
 602 }
 603
 604 static void tree_attach(struct exfat_node* dir, struct exfat_node* node)
 605 {
 606         node->parent = dir;
 607         if (dir->child)
 608         {
 609                 dir->child->prev = node;
 610                 node->next = dir->child;
 611         }
 612         dir->child = node;
 613 }
 614
 615 static void tree_detach(struct exfat_node* node)
 616 {
 617         if (node->prev)
 618                 node->prev->next = node->next;
 619         else /* this is the first node in the list */
 620                 node->parent->child = node->next;
 621         if (node->next)
 622                 node->next->prev = node->prev;
 623         node->parent = NULL;
 624         node->prev = NULL;
 625         node->next = NULL;
 626 }
 627
 628 static void reset_cache(struct exfat* ef, struct exfat_node* node)
 629 {
 630         char buffer[UTF8_BYTES(EXFAT_NAME_MAX) + 1];
 631
 632         while (node->child)
 633         {
 634                 struct exfat_node* p = node->child;
 635                 reset_cache(ef, p);
 636                 tree_detach(p);
 637                 free(p);
 638         }
 639         node->flags &= ~EXFAT_ATTRIB_CACHED;
 640         if (node->references != 0)
 641         {
 642                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 643                 exfat_warn("non-zero reference counter (%d) for '%s'",
 644                                 node->references, buffer);
 645         }
 646         if (node != ef->root && (node->flags & EXFAT_ATTRIB_DIRTY))
 647         {
 648                 exfat_get_name(node, buffer, sizeof(buffer) - 1);
 649                 exfat_bug("node '%s' is dirty", buffer);
 650         }
 651         while (node->references)
 652                 exfat_put_node(ef, node);
 653 }
 654
 655 void exfat_reset_cache(struct exfat* ef)
 656 {
 657         reset_cache(ef, ef->root);
 658 }
 659
 660 static bool next_entry(struct exfat* ef, const struct exfat_node* parent,
 661                 cluster_t* cluster, off_t* offset)
 662 {
 663         *offset += sizeof(struct exfat_entry);
 664         if (*offset % CLUSTER_SIZE(*ef->sb) == 0)
 665         {
 666                 *cluster = exfat_next_cluster(ef, parent, *cluster);
 667                 if (CLUSTER_INVALID(*cluster))
 668                 {
 669                         exfat_error("invalid cluster %#x while getting next entry",
 670                                         *cluster);
 671                         return false;
 672                 }
 673         }
 674         return true;
 675 }
 676
 677 int exfat_flush_node(struct exfat* ef, struct exfat_node* node)
 678 {
 679         cluster_t cluster;
 680         off_t offset;
 681         off_t meta1_offset, meta2_offset;
 682         struct exfat_entry_meta1 meta1;
 683         struct exfat_entry_meta2 meta2;
 684
 685         if (!(node->flags & EXFAT_ATTRIB_DIRTY))
 686                 return 0; /* no need to flush */
 687
 688         if (ef->ro)
 689                 exfat_bug("unable to flush node to read-only FS");
 690
 691         if (node->parent == NULL)
 692                 return 0; /* do not flush unlinked node */
 693
 694         cluster = node->entry_cluster;
 695         offset = node->entry_offset;
 696         meta1_offset = co2o(ef, cluster, offset);
 697         if (!next_entry(ef, node->parent, &cluster, &offset))
 698                 return -EIO;
 699         meta2_offset = co2o(ef, cluster, offset);
 700
 701         if (exfat_pread(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 702         {
 703                 exfat_error("failed to read meta1 entry on flush");
 704                 return -EIO;
 705         }
 706         if (meta1.type != EXFAT_ENTRY_FILE)
 707                 exfat_bug("invalid type of meta1: 0x%hhx", meta1.type);
 708         meta1.attrib = cpu_to_le16(node->flags);
 709         exfat_unix2exfat(node->mtime, &meta1.mdate, &meta1.mtime, &meta1.mtime_cs);
 710         exfat_unix2exfat(node->atime, &meta1.adate, &meta1.atime, NULL);
 711
 712         if (exfat_pread(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 713         {
 714                 exfat_error("failed to read meta2 entry on flush");
 715                 return -EIO;
 716         }
 717         if (meta2.type != EXFAT_ENTRY_FILE_INFO)
 718                 exfat_bug("invalid type of meta2: 0x%hhx", meta2.type);
 719         meta2.size = meta2.valid_size = cpu_to_le64(node->size);
 720         meta2.start_cluster = cpu_to_le32(node->start_cluster);
 721         meta2.flags = EXFAT_FLAG_ALWAYS1;
 722         /* empty files must not be marked as contiguous */
 723         if (node->size != 0 && IS_CONTIGUOUS(*node))
 724                 meta2.flags |= EXFAT_FLAG_CONTIGUOUS;
 725         /* name hash remains unchanged, no need to recalculate it */
 726
 727         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 728
 729         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1), meta1_offset) < 0)
 730         {
 731                 exfat_error("failed to write meta1 entry on flush");
 732                 return -EIO;
 733         }
 734         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2), meta2_offset) < 0)
 735         {
 736                 exfat_error("failed to write meta2 entry on flush");
 737                 return -EIO;
 738         }
 739
 740         node->flags &= ~EXFAT_ATTRIB_DIRTY;
 741         return exfat_flush(ef);
 742 }
 743
 744 static bool erase_entry(struct exfat* ef, struct exfat_node* node)
 745 {
 746         cluster_t cluster = node->entry_cluster;
 747         off_t offset = node->entry_offset;
 748         int name_entries = DIV_ROUND_UP(utf16_length(node->name), EXFAT_ENAME_MAX);
 749         uint8_t entry_type;
 750
 751         entry_type = EXFAT_ENTRY_FILE & ~EXFAT_ENTRY_VALID;
 752         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 753         {
 754                 exfat_error("failed to erase meta1 entry");
 755                 return false;
 756         }
 757
 758         if (!next_entry(ef, node->parent, &cluster, &offset))
 759                 return false;
 760         entry_type = EXFAT_ENTRY_FILE_INFO & ~EXFAT_ENTRY_VALID;
 761         if (exfat_pwrite(ef->dev, &entry_type, 1, co2o(ef, cluster, offset)) < 0)
 762         {
 763                 exfat_error("failed to erase meta2 entry");
 764                 return false;
 765         }
 766
 767         while (name_entries--)
 768         {
 769                 if (!next_entry(ef, node->parent, &cluster, &offset))
 770                         return false;
 771                 entry_type = EXFAT_ENTRY_FILE_NAME & ~EXFAT_ENTRY_VALID;
 772                 if (exfat_pwrite(ef->dev, &entry_type, 1,
 773                                 co2o(ef, cluster, offset)) < 0)
 774                 {
 775                         exfat_error("failed to erase name entry");
 776                         return false;
 777                 }
 778         }
 779         return true;
 780 }
 781
 782 static int shrink_directory(struct exfat* ef, struct exfat_node* dir,
 783                 off_t deleted_offset)
 784 {
 785         const struct exfat_node* node;
 786         const struct exfat_node* last_node;
 787         uint64_t entries = 0;
 788         uint64_t new_size;
 789
 790         if (!(dir->flags & EXFAT_ATTRIB_DIR))
 791                 exfat_bug("attempted to shrink a file");
 792         if (!(dir->flags & EXFAT_ATTRIB_CACHED))
 793                 exfat_bug("attempted to shrink uncached directory");
 794
 795         for (last_node = node = dir->child; node; node = node->next)
 796         {
 797                 if (deleted_offset < node->entry_offset)
 798                 {
 799                         /* there are other entries after the removed one, no way to shrink
 800                            this directory */
 801                         return 0;
 802                 }
 803                 if (last_node->entry_offset < node->entry_offset)
 804                         last_node = node;
 805         }
 806
 807         if (last_node)
 808         {
 809                 /* offset of the last entry */
 810                 entries += last_node->entry_offset / sizeof(struct exfat_entry);
 811                 /* two subentries with meta info */
 812                 entries += 2;
 813                 /* subentries with file name */
 814                 entries += DIV_ROUND_UP(utf16_length(last_node->name),
 815                                 EXFAT_ENAME_MAX);
 816         }
 817
 818         new_size = DIV_ROUND_UP(entries * sizeof(struct exfat_entry),
 819                                  CLUSTER_SIZE(*ef->sb)) * CLUSTER_SIZE(*ef->sb);
 820         if (new_size == 0) /* directory always has at least 1 cluster */
 821                 new_size = CLUSTER_SIZE(*ef->sb);
 822         if (new_size == dir->size)
 823                 return 0;
 824         return exfat_truncate(ef, dir, new_size, true);
 825 }
 826
 827 static int delete(struct exfat* ef, struct exfat_node* node)
 828 {
 829         struct exfat_node* parent = node->parent;
 830         off_t deleted_offset = node->entry_offset;
 831         int rc;
 832
 833         exfat_get_node(parent);
 834         if (!erase_entry(ef, node))
 835         {
 836                 exfat_put_node(ef, parent);
 837                 return -EIO;
 838         }
 839         exfat_update_mtime(parent);
 840         tree_detach(node);
 841         rc = shrink_directory(ef, parent, deleted_offset);
 842         node->flags |= EXFAT_ATTRIB_UNLINKED;
 843         if (rc != 0)
 844         {
 845                 exfat_flush_node(ef, parent);
 846                 exfat_put_node(ef, parent);
 847                 return rc;
 848         }
 849         rc = exfat_flush_node(ef, parent);
 850         exfat_put_node(ef, parent);
 851         return rc;
 852 }
 853
 854 int exfat_unlink(struct exfat* ef, struct exfat_node* node)
 855 {
 856         if (node->flags & EXFAT_ATTRIB_DIR)
 857                 return -EISDIR;
 858         return delete(ef, node);
 859 }
 860
 861 int exfat_rmdir(struct exfat* ef, struct exfat_node* node)
 862 {
 863         int rc;
 864
 865         if (!(node->flags & EXFAT_ATTRIB_DIR))
 866                 return -ENOTDIR;
 867         /* check that directory is empty */
 868         rc = exfat_cache_directory(ef, node);
 869         if (rc != 0)
 870                 return rc;
 871         if (node->child)
 872                 return -ENOTEMPTY;
 873         return delete(ef, node);
 874 }
 875
 876 static int grow_directory(struct exfat* ef, struct exfat_node* dir,
 877                 uint64_t asize, uint32_t difference)
 878 {
 879         return exfat_truncate(ef, dir,
 880                         DIV_ROUND_UP(asize + difference, CLUSTER_SIZE(*ef->sb))
 881                                 * CLUSTER_SIZE(*ef->sb), true);
 882 }
 883
 884 static int find_slot(struct exfat* ef, struct exfat_node* dir,
 885                 cluster_t* cluster, off_t* offset, int subentries)
 886 {
 887         struct iterator it;
 888         int rc;
 889         const struct exfat_entry* entry;
 890         int contiguous = 0;
 891
 892         rc = opendir(ef, dir, &it);
 893         if (rc != 0)
 894                 return rc;
 895         for (;;)
 896         {
 897                 if (contiguous == 0)
 898                 {
 899                         *cluster = it.cluster;
 900                         *offset = it.offset;
 901                 }
 902                 entry = get_entry_ptr(ef, &it);
 903                 if (entry->type & EXFAT_ENTRY_VALID)
 904                         contiguous = 0;
 905                 else
 906                         contiguous++;
 907                 if (contiguous == subentries)
 908                         break;  /* suitable slot is found */
 909                 if (it.offset + sizeof(struct exfat_entry) >= dir->size)
 910                 {
 911                         rc = grow_directory(ef, dir, dir->size,
 912                                         (subentries - contiguous) * sizeof(struct exfat_entry));
 913                         if (rc != 0)
 914                         {
 915                                 closedir(&it);
 916                                 return rc;
 917                         }
 918                 }
 919                 if (!fetch_next_entry(ef, dir, &it))
 920                 {
 921                         closedir(&it);
 922                         return -EIO;
 923                 }
 924         }
 925         closedir(&it);
 926         return 0;
 927 }
 928
 929 static int write_entry(struct exfat* ef, struct exfat_node* dir,
 930                 const le16_t* name, cluster_t cluster, off_t offset, uint16_t attrib)
 931 {
 932         struct exfat_node* node;
 933         struct exfat_entry_meta1 meta1;
 934         struct exfat_entry_meta2 meta2;
 935         const size_t name_length = utf16_length(name);
 936         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
 937         int i;
 938
 939         node = allocate_node();
 940         if (node == NULL)
 941                 return -ENOMEM;
 942         node->entry_cluster = cluster;
 943         node->entry_offset = offset;
 944         memcpy(node->name, name, name_length * sizeof(le16_t));
 945
 946         memset(&meta1, 0, sizeof(meta1));
 947         meta1.type = EXFAT_ENTRY_FILE;
 948         meta1.continuations = 1 + name_entries;
 949         meta1.attrib = cpu_to_le16(attrib);
 950         exfat_unix2exfat(time(NULL), &meta1.crdate, &meta1.crtime,
 951                         &meta1.crtime_cs);
 952         meta1.adate = meta1.mdate = meta1.crdate;
 953         meta1.atime = meta1.mtime = meta1.crtime;
 954         meta1.mtime_cs = meta1.crtime_cs; /* there is no atime_cs */
 955
 956         memset(&meta2, 0, sizeof(meta2));
 957         meta2.type = EXFAT_ENTRY_FILE_INFO;
 958         meta2.flags = EXFAT_FLAG_ALWAYS1;
 959         meta2.name_length = name_length;
 960         meta2.name_hash = exfat_calc_name_hash(ef, node->name);
 961         meta2.start_cluster = cpu_to_le32(EXFAT_CLUSTER_FREE);
 962
 963         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, node->name);
 964
 965         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
 966                         co2o(ef, cluster, offset)) < 0)
 967         {
 968                 exfat_error("failed to write meta1 entry");
 969                 return -EIO;
 970         }
 971         if (!next_entry(ef, dir, &cluster, &offset))
 972                 return -EIO;
 973         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
 974                         co2o(ef, cluster, offset)) < 0)
 975         {
 976                 exfat_error("failed to write meta2 entry");
 977                 return -EIO;
 978         }
 979         for (i = 0; i < name_entries; i++)
 980         {
 981                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
 982                 memcpy(name_entry.name, node->name + i * EXFAT_ENAME_MAX,
 983                                 MIN(EXFAT_ENAME_MAX, EXFAT_NAME_MAX - i * EXFAT_ENAME_MAX) *
 984                                 sizeof(le16_t));
 985                 if (!next_entry(ef, dir, &cluster, &offset))
 986                         return -EIO;
 987                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
 988                                 co2o(ef, cluster, offset)) < 0)
 989                 {
 990                         exfat_error("failed to write name entry");
 991                         return -EIO;
 992                 }
 993         }
 994
 995         init_node_meta1(node, &meta1);
 996         init_node_meta2(node, &meta2);
 997
 998         tree_attach(dir, node);
 999         exfat_update_mtime(dir);
1000         return 0;
1001 }
1002
1003 static int create(struct exfat* ef, const char* path, uint16_t attrib)
1004 {
1005         struct exfat_node* dir;
1006         struct exfat_node* existing;
1007         cluster_t cluster = EXFAT_CLUSTER_BAD;
1008         off_t offset = -1;
1009         le16_t name[EXFAT_NAME_MAX + 1];
1010         int rc;
1011
1012         rc = exfat_split(ef, &dir, &existing, name, path);
1013         if (rc != 0)
1014                 return rc;
1015         if (existing != NULL)
1016         {
1017                 exfat_put_node(ef, existing);
1018                 exfat_put_node(ef, dir);
1019                 return -EEXIST;
1020         }
1021
1022         rc = find_slot(ef, dir, &cluster, &offset,
1023                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1024         if (rc != 0)
1025         {
1026                 exfat_put_node(ef, dir);
1027                 return rc;
1028         }
1029         rc = write_entry(ef, dir, name, cluster, offset, attrib);
1030         if (rc != 0)
1031         {
1032                 exfat_put_node(ef, dir);
1033                 return rc;
1034         }
1035         rc = exfat_flush_node(ef, dir);
1036         exfat_put_node(ef, dir);
1037         return rc;
1038 }
1039
1040 int exfat_mknod(struct exfat* ef, const char* path)
1041 {
1042         return create(ef, path, EXFAT_ATTRIB_ARCH);
1043 }
1044
1045 int exfat_mkdir(struct exfat* ef, const char* path)
1046 {
1047         int rc;
1048         struct exfat_node* node;
1049
1050         rc = create(ef, path, EXFAT_ATTRIB_DIR);
1051         if (rc != 0)
1052                 return rc;
1053         rc = exfat_lookup(ef, &node, path);
1054         if (rc != 0)
1055                 return 0;
1056         /* directories always have at least one cluster */
1057         rc = exfat_truncate(ef, node, CLUSTER_SIZE(*ef->sb), true);
1058         if (rc != 0)
1059         {
1060                 delete(ef, node);
1061                 exfat_put_node(ef, node);
1062                 return rc;
1063         }
1064         rc = exfat_flush_node(ef, node);
1065         if (rc != 0)
1066         {
1067                 delete(ef, node);
1068                 exfat_put_node(ef, node);
1069                 return rc;
1070         }
1071         exfat_put_node(ef, node);
1072         return 0;
1073 }
1074
1075 static int rename_entry(struct exfat* ef, struct exfat_node* dir,
1076                 struct exfat_node* node, const le16_t* name, cluster_t new_cluster,
1077                 off_t new_offset)
1078 {
1079         struct exfat_entry_meta1 meta1;
1080         struct exfat_entry_meta2 meta2;
1081         cluster_t old_cluster = node->entry_cluster;
1082         off_t old_offset = node->entry_offset;
1083         const size_t name_length = utf16_length(name);
1084         const int name_entries = DIV_ROUND_UP(name_length, EXFAT_ENAME_MAX);
1085         int i;
1086
1087         if (exfat_pread(ef->dev, &meta1, sizeof(meta1),
1088                         co2o(ef, old_cluster, old_offset)) < 0)
1089         {
1090                 exfat_error("failed to read meta1 entry on rename");
1091                 return -EIO;
1092         }
1093         if (!next_entry(ef, node->parent, &old_cluster, &old_offset))
1094                 return -EIO;
1095         if (exfat_pread(ef->dev, &meta2, sizeof(meta2),
1096                         co2o(ef, old_cluster, old_offset)) < 0)
1097         {
1098                 exfat_error("failed to read meta2 entry on rename");
1099                 return -EIO;
1100         }
1101         meta1.continuations = 1 + name_entries;
1102         meta2.name_hash = exfat_calc_name_hash(ef, name);
1103         meta2.name_length = name_length;
1104         meta1.checksum = exfat_calc_checksum(&meta1, &meta2, name);
1105
1106         if (!erase_entry(ef, node))
1107                 return -EIO;
1108
1109         node->entry_cluster = new_cluster;
1110         node->entry_offset = new_offset;
1111
1112         if (exfat_pwrite(ef->dev, &meta1, sizeof(meta1),
1113                         co2o(ef, new_cluster, new_offset)) < 0)
1114         {
1115                 exfat_error("failed to write meta1 entry on rename");
1116                 return -EIO;
1117         }
1118         if (!next_entry(ef, dir, &new_cluster, &new_offset))
1119                 return -EIO;
1120         if (exfat_pwrite(ef->dev, &meta2, sizeof(meta2),
1121                         co2o(ef, new_cluster, new_offset)) < 0)
1122         {
1123                 exfat_error("failed to write meta2 entry on rename");
1124                 return -EIO;
1125         }
1126
1127         for (i = 0; i < name_entries; i++)
1128         {
1129                 struct exfat_entry_name name_entry = {EXFAT_ENTRY_FILE_NAME, 0};
1130                 memcpy(name_entry.name, name + i * EXFAT_ENAME_MAX,
1131                                 EXFAT_ENAME_MAX * sizeof(le16_t));
1132                 if (!next_entry(ef, dir, &new_cluster, &new_offset))
1133                         return -EIO;
1134                 if (exfat_pwrite(ef->dev, &name_entry, sizeof(name_entry),
1135                                 co2o(ef, new_cluster, new_offset)) < 0)
1136                 {
1137                         exfat_error("failed to write name entry on rename");
1138                         return -EIO;
1139                 }
1140         }
1141
1142         memcpy(node->name, name, (EXFAT_NAME_MAX + 1) * sizeof(le16_t));
1143         tree_detach(node);
1144         tree_attach(dir, node);
1145         return 0;
1146 }
1147
1148 int exfat_rename(struct exfat* ef, const char* old_path, const char* new_path)
1149 {
1150         struct exfat_node* node;
1151         struct exfat_node* existing;
1152         struct exfat_node* dir;
1153         cluster_t cluster = EXFAT_CLUSTER_BAD;
1154         off_t offset = -1;
1155         le16_t name[EXFAT_NAME_MAX + 1];
1156         int rc;
1157
1158         rc = exfat_lookup(ef, &node, old_path);
1159         if (rc != 0)
1160                 return rc;
1161
1162         rc = exfat_split(ef, &dir, &existing, name, new_path);
1163         if (rc != 0)
1164         {
1165                 exfat_put_node(ef, node);
1166                 return rc;
1167         }
1168
1169         /* check that target is not a subdirectory of the source */
1170         if (node->flags & EXFAT_ATTRIB_DIR)
1171         {
1172                 struct exfat_node* p;
1173
1174                 for (p = dir; p; p = p->parent)
1175                         if (node == p)
1176                         {
1177                                 if (existing != NULL)
1178                                         exfat_put_node(ef, existing);
1179                                 exfat_put_node(ef, dir);
1180                                 exfat_put_node(ef, node);
1181                                 return -EINVAL;
1182                         }
1183         }
1184
1185         if (existing != NULL)
1186         {
1187                 /* remove target if it's not the same node as source */
1188                 if (existing != node)
1189                 {
1190                         if (existing->flags & EXFAT_ATTRIB_DIR)
1191                         {
1192                                 if (node->flags & EXFAT_ATTRIB_DIR)
1193                                         rc = exfat_rmdir(ef, existing);
1194                                 else
1195                                         rc = -ENOTDIR;
1196                         }
1197                         else
1198                         {
1199                                 if (!(node->flags & EXFAT_ATTRIB_DIR))
1200                                         rc = exfat_unlink(ef, existing);
1201                                 else
1202                                         rc = -EISDIR;
1203                         }
1204                         exfat_put_node(ef, existing);
1205                         if (rc != 0)
1206                         {
1207                                 /* free clusters even if something went wrong; overwise they
1208                                    will be just lost */
1209                                 exfat_cleanup_node(ef, existing);
1210                                 exfat_put_node(ef, dir);
1211                                 exfat_put_node(ef, node);
1212                                 return rc;
1213                         }
1214                         rc = exfat_cleanup_node(ef, existing);
1215                         if (rc != 0)
1216                         {
1217                                 exfat_put_node(ef, dir);
1218                                 exfat_put_node(ef, node);
1219                                 return rc;
1220                         }
1221                 }
1222                 else
1223                         exfat_put_node(ef, existing);
1224         }
1225
1226         rc = find_slot(ef, dir, &cluster, &offset,
1227                         2 + DIV_ROUND_UP(utf16_length(name), EXFAT_ENAME_MAX));
1228         if (rc != 0)
1229         {
1230                 exfat_put_node(ef, dir);
1231                 exfat_put_node(ef, node);
1232                 return rc;
1233         }
1234         rc = rename_entry(ef, dir, node, name, cluster, offset);
1235         exfat_put_node(ef, dir);
1236         exfat_put_node(ef, node);
1237         return rc;
1238 }
1239
1240 void exfat_utimes(struct exfat_node* node, const struct timespec tv[2])
1241 {
1242         node->atime = tv[0].tv_sec;
1243         node->mtime = tv[1].tv_sec;
1244         node->flags |= EXFAT_ATTRIB_DIRTY;
1245 }
1246
1247 void exfat_update_atime(struct exfat_node* node)
1248 {
1249         node->atime = time(NULL);
1250         node->flags |= EXFAT_ATTRIB_DIRTY;
1251 }
1252
1253 void exfat_update_mtime(struct exfat_node* node)
1254 {
1255         node->mtime = time(NULL);
1256         node->flags |= EXFAT_ATTRIB_DIRTY;
1257 }
1258
1259 const char* exfat_get_label(struct exfat* ef)
1260 {
1261         return ef->label;
1262 }
1263
1264 static int find_label(struct exfat* ef, cluster_t* cluster, off_t* offset)
1265 {
1266         struct iterator it;
1267         int rc;
1268
1269         rc = opendir(ef, ef->root, &it);
1270         if (rc != 0)
1271                 return rc;
1272
1273         for (;;)
1274         {
1275                 if (it.offset >= ef->root->size)
1276                 {
1277                         closedir(&it);
1278                         return -ENOENT;
1279                 }
1280
1281                 if (get_entry_ptr(ef, &it)->type == EXFAT_ENTRY_LABEL)
1282                 {
1283                         *cluster = it.cluster;
1284                         *offset = it.offset;
1285                         closedir(&it);
1286                         return 0;
1287                 }
1288
1289                 if (!fetch_next_entry(ef, ef->root, &it))
1290                 {
1291                         closedir(&it);
1292                         return -EIO;
1293                 }
1294         }
1295 }
1296
1297 int exfat_set_label(struct exfat* ef, const char* label)
1298 {
1299         le16_t label_utf16[EXFAT_ENAME_MAX + 1];
1300         int rc;
1301         cluster_t cluster;
1302         off_t offset;
1303         struct exfat_entry_label entry;
1304
1305         memset(label_utf16, 0, sizeof(label_utf16));
1306         rc = utf8_to_utf16(label_utf16, label, EXFAT_ENAME_MAX, strlen(label));
1307         if (rc != 0)
1308                 return rc;
1309
1310         rc = find_label(ef, &cluster, &offset);
1311         if (rc == -ENOENT)
1312                 rc = find_slot(ef, ef->root, &cluster, &offset, 1);
1313         if (rc != 0)
1314                 return rc;
1315
1316         entry.type = EXFAT_ENTRY_LABEL;
1317         entry.length = utf16_length(label_utf16);
1318         memcpy(entry.name, label_utf16, sizeof(entry.name));
1319         if (entry.length == 0)
1320                 entry.type ^= EXFAT_ENTRY_VALID;
1321
1322         if (exfat_pwrite(ef->dev, &entry, sizeof(struct exfat_entry_label),
1323                         co2o(ef, cluster, offset)) < 0)
1324         {
1325                 exfat_error("failed to write label entry");
1326                 return -EIO;
1327         }
1328         strcpy(ef->label, label);
1329         return 0;
1330 }