LinuxGUI/Ventoy2Disk/Lib/exfat/src/libexfat/cluster.c

   1 /*
   2         cluster.c (03.09.09)
   3         exFAT file system implementation library.
   4
   5         Free exFAT implementation.
   6         Copyright (C) 2010-2018  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 /*
  29  * Sector to absolute offset.
  30  */
  31 static off_t s2o(const struct exfat* ef, off_t sector)
  32 {
  33         return sector << ef->sb->sector_bits;
  34 }
  35
  36 /*
  37  * Cluster to sector.
  38  */
  39 static off_t c2s(const struct exfat* ef, cluster_t cluster)
  40 {
  41         if (cluster < EXFAT_FIRST_DATA_CLUSTER)
  42                 exfat_bug("invalid cluster number %u", cluster);
  43         return le32_to_cpu(ef->sb->cluster_sector_start) +
  44                 ((off_t) (cluster - EXFAT_FIRST_DATA_CLUSTER) << ef->sb->spc_bits);
  45 }
  46
  47 /*
  48  * Cluster to absolute offset.
  49  */
  50 off_t exfat_c2o(const struct exfat* ef, cluster_t cluster)
  51 {
  52         return s2o(ef, c2s(ef, cluster));
  53 }
  54
  55 /*
  56  * Sector to cluster.
  57  */
  58 static cluster_t s2c(const struct exfat* ef, off_t sector)
  59 {
  60         return ((sector - le32_to_cpu(ef->sb->cluster_sector_start)) >>
  61                         ef->sb->spc_bits) + EXFAT_FIRST_DATA_CLUSTER;
  62 }
  63
  64 /*
  65  * Size in bytes to size in clusters (rounded upwards).
  66  */
  67 static uint32_t bytes2clusters(const struct exfat* ef, uint64_t bytes)
  68 {
  69         uint64_t cluster_size = CLUSTER_SIZE(*ef->sb);
  70         return DIV_ROUND_UP(bytes, cluster_size);
  71 }
  72
  73 cluster_t exfat_next_cluster(const struct exfat* ef,
  74                 const struct exfat_node* node, cluster_t cluster)
  75 {
  76         le32_t next;
  77         off_t fat_offset;
  78
  79         if (cluster < EXFAT_FIRST_DATA_CLUSTER)
  80                 exfat_bug("bad cluster 0x%x", cluster);
  81
  82         if (node->is_contiguous)
  83                 return cluster + 1;
  84         fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
  85                 + cluster * sizeof(cluster_t);
  86         if (exfat_pread(ef->dev, &next, sizeof(next), fat_offset) < 0)
  87                 return EXFAT_CLUSTER_BAD; /* the caller should handle this and print
  88                                              appropriate error message */
  89         return le32_to_cpu(next);
  90 }
  91
  92 cluster_t exfat_advance_cluster(const struct exfat* ef,
  93                 struct exfat_node* node, uint32_t count)
  94 {
  95         uint32_t i;
  96
  97         if (node->fptr_index > count)
  98         {
  99                 node->fptr_index = 0;
 100                 node->fptr_cluster = node->start_cluster;
 101         }
 102
 103         for (i = node->fptr_index; i < count; i++)
 104         {
 105                 node->fptr_cluster = exfat_next_cluster(ef, node, node->fptr_cluster);
 106                 if (CLUSTER_INVALID(*ef->sb, node->fptr_cluster))
 107                         break; /* the caller should handle this and print appropriate
 108                                   error message */
 109         }
 110         node->fptr_index = count;
 111         return node->fptr_cluster;
 112 }
 113
 114 static cluster_t find_bit_and_set(bitmap_t* bitmap, size_t start, size_t end)
 115 {
 116         const size_t start_index = start / sizeof(bitmap_t) / 8;
 117         const size_t end_index = DIV_ROUND_UP(end, sizeof(bitmap_t) * 8);
 118         size_t i;
 119         size_t start_bitindex;
 120         size_t end_bitindex;
 121         size_t c;
 122
 123         for (i = start_index; i < end_index; i++)
 124         {
 125                 if (bitmap[i] == ~((bitmap_t) 0))
 126                         continue;
 127                 start_bitindex = MAX(i * sizeof(bitmap_t) * 8, start);
 128                 end_bitindex = MIN((i + 1) * sizeof(bitmap_t) * 8, end);
 129                 for (c = start_bitindex; c < end_bitindex; c++)
 130                         if (BMAP_GET(bitmap, c) == 0)
 131                         {
 132                                 BMAP_SET(bitmap, c);
 133                                 return c + EXFAT_FIRST_DATA_CLUSTER;
 134                         }
 135         }
 136         return EXFAT_CLUSTER_END;
 137 }
 138
 139 static int flush_nodes(struct exfat* ef, struct exfat_node* node)
 140 {
 141         struct exfat_node* p;
 142
 143         for (p = node->child; p != NULL; p = p->next)
 144         {
 145                 int rc = flush_nodes(ef, p);
 146                 if (rc != 0)
 147                         return rc;
 148         }
 149         return exfat_flush_node(ef, node);
 150 }
 151
 152 int exfat_flush_nodes(struct exfat* ef)
 153 {
 154         return flush_nodes(ef, ef->root);
 155 }
 156
 157 int exfat_flush(struct exfat* ef)
 158 {
 159         if (ef->cmap.dirty)
 160         {
 161                 if (exfat_pwrite(ef->dev, ef->cmap.chunk,
 162                                 BMAP_SIZE(ef->cmap.chunk_size),
 163                                 exfat_c2o(ef, ef->cmap.start_cluster)) < 0)
 164                 {
 165                         exfat_error("failed to write clusters bitmap");
 166                         return -EIO;
 167                 }
 168                 ef->cmap.dirty = false;
 169         }
 170
 171         return 0;
 172 }
 173
 174 static bool set_next_cluster(const struct exfat* ef, bool contiguous,
 175                 cluster_t current, cluster_t next)
 176 {
 177         off_t fat_offset;
 178         le32_t next_le32;
 179
 180         if (contiguous)
 181                 return true;
 182         fat_offset = s2o(ef, le32_to_cpu(ef->sb->fat_sector_start))
 183                 + current * sizeof(cluster_t);
 184         next_le32 = cpu_to_le32(next);
 185         if (exfat_pwrite(ef->dev, &next_le32, sizeof(next_le32), fat_offset) < 0)
 186         {
 187                 exfat_error("failed to write the next cluster %#x after %#x", next,
 188                                 current);
 189                 return false;
 190         }
 191         return true;
 192 }
 193
 194 static cluster_t allocate_cluster(struct exfat* ef, cluster_t hint)
 195 {
 196         cluster_t cluster;
 197
 198         hint -= EXFAT_FIRST_DATA_CLUSTER;
 199         if (hint >= ef->cmap.chunk_size)
 200                 hint = 0;
 201
 202         cluster = find_bit_and_set(ef->cmap.chunk, hint, ef->cmap.chunk_size);
 203         if (cluster == EXFAT_CLUSTER_END)
 204                 cluster = find_bit_and_set(ef->cmap.chunk, 0, hint);
 205         if (cluster == EXFAT_CLUSTER_END)
 206         {
 207                 exfat_error("no free space left");
 208                 return EXFAT_CLUSTER_END;
 209         }
 210
 211         ef->cmap.dirty = true;
 212         return cluster;
 213 }
 214
 215 static void free_cluster(struct exfat* ef, cluster_t cluster)
 216 {
 217         if (cluster - EXFAT_FIRST_DATA_CLUSTER >= ef->cmap.size)
 218                 exfat_bug("caller must check cluster validity (%#x, %#x)", cluster,
 219                                 ef->cmap.size);
 220
 221         BMAP_CLR(ef->cmap.chunk, cluster - EXFAT_FIRST_DATA_CLUSTER);
 222         ef->cmap.dirty = true;
 223 }
 224
 225 static bool make_noncontiguous(const struct exfat* ef, cluster_t first,
 226                 cluster_t last)
 227 {
 228         cluster_t c;
 229
 230         for (c = first; c < last; c++)
 231                 if (!set_next_cluster(ef, false, c, c + 1))
 232                         return false;
 233         return true;
 234 }
 235
 236 static int shrink_file(struct exfat* ef, struct exfat_node* node,
 237                 uint32_t current, uint32_t difference);
 238
 239 static int grow_file(struct exfat* ef, struct exfat_node* node,
 240                 uint32_t current, uint32_t difference)
 241 {
 242         cluster_t previous;
 243         cluster_t next;
 244         uint32_t allocated = 0;
 245
 246         if (difference == 0)
 247                 exfat_bug("zero clusters count passed");
 248
 249         if (node->start_cluster != EXFAT_CLUSTER_FREE)
 250         {
 251                 /* get the last cluster of the file */
 252                 previous = exfat_advance_cluster(ef, node, current - 1);
 253                 if (CLUSTER_INVALID(*ef->sb, previous))
 254                 {
 255                         exfat_error("invalid cluster 0x%x while growing", previous);
 256                         return -EIO;
 257                 }
 258         }
 259         else
 260         {
 261                 if (node->fptr_index != 0)
 262                         exfat_bug("non-zero pointer index (%u)", node->fptr_index);
 263                 /* file does not have clusters (i.e. is empty), allocate
 264                    the first one for it */
 265                 previous = allocate_cluster(ef, 0);
 266                 if (CLUSTER_INVALID(*ef->sb, previous))
 267                         return -ENOSPC;
 268                 node->fptr_cluster = node->start_cluster = previous;
 269                 allocated = 1;
 270                 /* file consists of only one cluster, so it's contiguous */
 271                 node->is_contiguous = true;
 272         }
 273
 274         while (allocated < difference)
 275         {
 276                 next = allocate_cluster(ef, previous + 1);
 277                 if (CLUSTER_INVALID(*ef->sb, next))
 278                 {
 279                         if (allocated != 0)
 280                                 shrink_file(ef, node, current + allocated, allocated);
 281                         return -ENOSPC;
 282                 }
 283                 if (next != previous - 1 && node->is_contiguous)
 284                 {
 285                         /* it's a pity, but we are not able to keep the file contiguous
 286                            anymore */
 287                         if (!make_noncontiguous(ef, node->start_cluster, previous))
 288                                 return -EIO;
 289                         node->is_contiguous = false;
 290                         node->is_dirty = true;
 291                 }
 292                 if (!set_next_cluster(ef, node->is_contiguous, previous, next))
 293                         return -EIO;
 294                 previous = next;
 295                 allocated++;
 296         }
 297
 298         if (!set_next_cluster(ef, node->is_contiguous, previous,
 299                         EXFAT_CLUSTER_END))
 300                 return -EIO;
 301         return 0;
 302 }
 303
 304 static int shrink_file(struct exfat* ef, struct exfat_node* node,
 305                 uint32_t current, uint32_t difference)
 306 {
 307         cluster_t previous;
 308         cluster_t next;
 309
 310         if (difference == 0)
 311                 exfat_bug("zero difference passed");
 312         if (node->start_cluster == EXFAT_CLUSTER_FREE)
 313                 exfat_bug("unable to shrink empty file (%u clusters)", current);
 314         if (current < difference)
 315                 exfat_bug("file underflow (%u < %u)", current, difference);
 316
 317         /* crop the file */
 318         if (current > difference)
 319         {
 320                 cluster_t last = exfat_advance_cluster(ef, node,
 321                                 current - difference - 1);
 322                 if (CLUSTER_INVALID(*ef->sb, last))
 323                 {
 324                         exfat_error("invalid cluster 0x%x while shrinking", last);
 325                         return -EIO;
 326                 }
 327                 previous = exfat_next_cluster(ef, node, last);
 328                 if (!set_next_cluster(ef, node->is_contiguous, last,
 329                                 EXFAT_CLUSTER_END))
 330                         return -EIO;
 331         }
 332         else
 333         {
 334                 previous = node->start_cluster;
 335                 node->start_cluster = EXFAT_CLUSTER_FREE;
 336                 node->is_dirty = true;
 337         }
 338         node->fptr_index = 0;
 339         node->fptr_cluster = node->start_cluster;
 340
 341         /* free remaining clusters */
 342         while (difference--)
 343         {
 344                 if (CLUSTER_INVALID(*ef->sb, previous))
 345                 {
 346                         exfat_error("invalid cluster 0x%x while freeing after shrink",
 347                                         previous);
 348                         return -EIO;
 349                 }
 350
 351                 next = exfat_next_cluster(ef, node, previous);
 352                 if (!set_next_cluster(ef, node->is_contiguous, previous,
 353                                 EXFAT_CLUSTER_FREE))
 354                         return -EIO;
 355                 free_cluster(ef, previous);
 356                 previous = next;
 357         }
 358         return 0;
 359 }
 360
 361 static bool erase_raw(struct exfat* ef, size_t size, off_t offset)
 362 {
 363         if (exfat_pwrite(ef->dev, ef->zero_cluster, size, offset) < 0)
 364         {
 365                 exfat_error("failed to erase %zu bytes at %"PRId64, size, offset);
 366                 return false;
 367         }
 368         return true;
 369 }
 370
 371 static int erase_range(struct exfat* ef, struct exfat_node* node,
 372                 uint64_t begin, uint64_t end)
 373 {
 374         uint64_t cluster_boundary;
 375         cluster_t cluster;
 376
 377         if (begin >= end)
 378                 return 0;
 379
 380         cluster_boundary = (begin | (CLUSTER_SIZE(*ef->sb) - 1)) + 1;
 381         cluster = exfat_advance_cluster(ef, node,
 382                         begin / CLUSTER_SIZE(*ef->sb));
 383         if (CLUSTER_INVALID(*ef->sb, cluster))
 384         {
 385                 exfat_error("invalid cluster 0x%x while erasing", cluster);
 386                 return -EIO;
 387         }
 388         /* erase from the beginning to the closest cluster boundary */
 389         if (!erase_raw(ef, MIN(cluster_boundary, end) - begin,
 390                         exfat_c2o(ef, cluster) + begin % CLUSTER_SIZE(*ef->sb)))
 391                 return -EIO;
 392         /* erase whole clusters */
 393         while (cluster_boundary < end)
 394         {
 395                 cluster = exfat_next_cluster(ef, node, cluster);
 396                 /* the cluster cannot be invalid because we have just allocated it */
 397                 if (CLUSTER_INVALID(*ef->sb, cluster))
 398                         exfat_bug("invalid cluster 0x%x after allocation", cluster);
 399                 if (!erase_raw(ef, CLUSTER_SIZE(*ef->sb), exfat_c2o(ef, cluster)))
 400                         return -EIO;
 401                 cluster_boundary += CLUSTER_SIZE(*ef->sb);
 402         }
 403         return 0;
 404 }
 405
 406 int exfat_truncate(struct exfat* ef, struct exfat_node* node, uint64_t size,
 407                 bool erase)
 408 {
 409         uint32_t c1 = bytes2clusters(ef, node->size);
 410         uint32_t c2 = bytes2clusters(ef, size);
 411         int rc = 0;
 412
 413         if (node->references == 0 && node->parent)
 414                 exfat_bug("no references, node changes can be lost");
 415
 416         if (node->size == size)
 417                 return 0;
 418
 419         if (c1 < c2)
 420                 rc = grow_file(ef, node, c1, c2 - c1);
 421         else if (c1 > c2)
 422                 rc = shrink_file(ef, node, c1, c1 - c2);
 423
 424         if (rc != 0)
 425                 return rc;
 426
 427         if (erase)
 428         {
 429                 rc = erase_range(ef, node, node->size, size);
 430                 if (rc != 0)
 431                         return rc;
 432         }
 433
 434         exfat_update_mtime(node);
 435         node->size = size;
 436         node->is_dirty = true;
 437         return 0;
 438 }
 439
 440 uint32_t exfat_count_free_clusters(const struct exfat* ef)
 441 {
 442         uint32_t free_clusters = 0;
 443         uint32_t i;
 444
 445         for (i = 0; i < ef->cmap.size; i++)
 446                 if (BMAP_GET(ef->cmap.chunk, i) == 0)
 447                         free_clusters++;
 448         return free_clusters;
 449 }
 450
 451 static int find_used_clusters(const struct exfat* ef,
 452                 cluster_t* a, cluster_t* b)
 453 {
 454         const cluster_t end = le32_to_cpu(ef->sb->cluster_count);
 455
 456         /* find first used cluster */
 457         for (*a = *b + 1; *a < end; (*a)++)
 458                 if (BMAP_GET(ef->cmap.chunk, *a - EXFAT_FIRST_DATA_CLUSTER))
 459                         break;
 460         if (*a >= end)
 461                 return 1;
 462
 463         /* find last contiguous used cluster */
 464         for (*b = *a; *b < end; (*b)++)
 465                 if (BMAP_GET(ef->cmap.chunk, *b - EXFAT_FIRST_DATA_CLUSTER) == 0)
 466                 {
 467                         (*b)--;
 468                         break;
 469                 }
 470
 471         return 0;
 472 }
 473
 474 int exfat_find_used_sectors(const struct exfat* ef, off_t* a, off_t* b)
 475 {
 476         cluster_t ca, cb;
 477
 478         if (*a == 0 && *b == 0)
 479                 ca = cb = EXFAT_FIRST_DATA_CLUSTER - 1;
 480         else
 481         {
 482                 ca = s2c(ef, *a);
 483                 cb = s2c(ef, *b);
 484         }
 485         if (find_used_clusters(ef, &ca, &cb) != 0)
 486                 return 1;
 487         if (*a != 0 || *b != 0)
 488                 *a = c2s(ef, ca);
 489         *b = c2s(ef, cb) + (CLUSTER_SIZE(*ef->sb) - 1) / SECTOR_SIZE(*ef->sb);
 490         return 0;
 491 }