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