fs/fat/fat_write.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * fat_write.c
   4  *
   5  * R/W (V)FAT 12/16/32 filesystem implementation by Donggeun Kim
   6  */
   7
   8 #include <common.h>
   9 #include <command.h>
  10 #include <config.h>
  11 #include <fat.h>
  12 #include <log.h>
  13 #include <malloc.h>
  14 #include <asm/byteorder.h>
  15 #include <part.h>
  16 #include <asm/cache.h>
  17 #include <linux/ctype.h>
  18 #include <div64.h>
  19 #include <linux/math64.h>
  20 #include "fat.c"
  21
  22 static void uppercase(char *str, int len)
  23 {
  24         int i;
  25
  26         for (i = 0; i < len; i++) {
  27                 *str = toupper(*str);
  28                 str++;
  29         }
  30 }
  31
  32 static int total_sector;
  33 static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
  34 {
  35         ulong ret;
  36
  37         if (!cur_dev)
  38                 return -1;
  39
  40         if (cur_part_info.start + block + nr_blocks >
  41                 cur_part_info.start + total_sector) {
  42                 printf("error: overflow occurs\n");
  43                 return -1;
  44         }
  45
  46         ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
  47         if (nr_blocks && ret == 0)
  48                 return -1;
  49
  50         return ret;
  51 }
  52
  53 /**
  54  * set_name() - set short name in directory entry
  55  *
  56  * @dirent:     directory entry
  57  * @filename:   long file name
  58  */
  59 static void set_name(dir_entry *dirent, const char *filename)
  60 {
  61         char s_name[VFAT_MAXLEN_BYTES];
  62         char *period;
  63         int period_location, len, i, ext_num;
  64
  65         if (filename == NULL)
  66                 return;
  67
  68         len = strlen(filename);
  69         if (len == 0)
  70                 return;
  71
  72         strncpy(s_name, filename, VFAT_MAXLEN_BYTES - 1);
  73         s_name[VFAT_MAXLEN_BYTES - 1] = '\0';
  74         uppercase(s_name, len);
  75
  76         period = strchr(s_name, '.');
  77         if (period == NULL) {
  78                 period_location = len;
  79                 ext_num = 0;
  80         } else {
  81                 period_location = period - s_name;
  82                 ext_num = len - period_location - 1;
  83         }
  84
  85         /* Pad spaces when the length of file name is shorter than eight */
  86         if (period_location < 8) {
  87                 memcpy(dirent->name, s_name, period_location);
  88                 for (i = period_location; i < 8; i++)
  89                         dirent->name[i] = ' ';
  90         } else if (period_location == 8) {
  91                 memcpy(dirent->name, s_name, period_location);
  92         } else {
  93                 memcpy(dirent->name, s_name, 6);
  94                 /*
  95                  * TODO: Translating two long names with the same first six
  96                  *       characters to the same short name is utterly wrong.
  97                  *       Short names must be unique.
  98                  */
  99                 dirent->name[6] = '~';
 100                 dirent->name[7] = '1';
 101         }
 102
 103         if (ext_num < 3) {
 104                 memcpy(dirent->ext, s_name + period_location + 1, ext_num);
 105                 for (i = ext_num; i < 3; i++)
 106                         dirent->ext[i] = ' ';
 107         } else
 108                 memcpy(dirent->ext, s_name + period_location + 1, 3);
 109
 110         debug("name : %s\n", dirent->name);
 111         debug("ext : %s\n", dirent->ext);
 112 }
 113
 114 /*
 115  * Write fat buffer into block device
 116  */
 117 static int flush_dirty_fat_buffer(fsdata *mydata)
 118 {
 119         int getsize = FATBUFBLOCKS;
 120         __u32 fatlength = mydata->fatlength;
 121         __u8 *bufptr = mydata->fatbuf;
 122         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 123
 124         debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
 125               (int)mydata->fat_dirty);
 126
 127         if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
 128                 return 0;
 129
 130         /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 131         if (startblock + getsize > fatlength)
 132                 getsize = fatlength - startblock;
 133
 134         startblock += mydata->fat_sect;
 135
 136         /* Write FAT buf */
 137         if (disk_write(startblock, getsize, bufptr) < 0) {
 138                 debug("error: writing FAT blocks\n");
 139                 return -1;
 140         }
 141
 142         if (mydata->fats == 2) {
 143                 /* Update corresponding second FAT blocks */
 144                 startblock += mydata->fatlength;
 145                 if (disk_write(startblock, getsize, bufptr) < 0) {
 146                         debug("error: writing second FAT blocks\n");
 147                         return -1;
 148                 }
 149         }
 150         mydata->fat_dirty = 0;
 151
 152         return 0;
 153 }
 154
 155 /*
 156  * Set the file name information from 'name' into 'slotptr',
 157  */
 158 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 159 {
 160         int j, end_idx = 0;
 161
 162         for (j = 0; j <= 8; j += 2) {
 163                 if (name[*idx] == 0x00) {
 164                         slotptr->name0_4[j] = 0;
 165                         slotptr->name0_4[j + 1] = 0;
 166                         end_idx++;
 167                         goto name0_4;
 168                 }
 169                 slotptr->name0_4[j] = name[*idx];
 170                 (*idx)++;
 171                 end_idx++;
 172         }
 173         for (j = 0; j <= 10; j += 2) {
 174                 if (name[*idx] == 0x00) {
 175                         slotptr->name5_10[j] = 0;
 176                         slotptr->name5_10[j + 1] = 0;
 177                         end_idx++;
 178                         goto name5_10;
 179                 }
 180                 slotptr->name5_10[j] = name[*idx];
 181                 (*idx)++;
 182                 end_idx++;
 183         }
 184         for (j = 0; j <= 2; j += 2) {
 185                 if (name[*idx] == 0x00) {
 186                         slotptr->name11_12[j] = 0;
 187                         slotptr->name11_12[j + 1] = 0;
 188                         end_idx++;
 189                         goto name11_12;
 190                 }
 191                 slotptr->name11_12[j] = name[*idx];
 192                 (*idx)++;
 193                 end_idx++;
 194         }
 195
 196         if (name[*idx] == 0x00)
 197                 return 1;
 198
 199         return 0;
 200 /* Not used characters are filled with 0xff 0xff */
 201 name0_4:
 202         for (; end_idx < 5; end_idx++) {
 203                 slotptr->name0_4[end_idx * 2] = 0xff;
 204                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 205         }
 206         end_idx = 5;
 207 name5_10:
 208         end_idx -= 5;
 209         for (; end_idx < 6; end_idx++) {
 210                 slotptr->name5_10[end_idx * 2] = 0xff;
 211                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 212         }
 213         end_idx = 11;
 214 name11_12:
 215         end_idx -= 11;
 216         for (; end_idx < 2; end_idx++) {
 217                 slotptr->name11_12[end_idx * 2] = 0xff;
 218                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 219         }
 220
 221         return 1;
 222 }
 223
 224 static int new_dir_table(fat_itr *itr);
 225 static int flush_dir(fat_itr *itr);
 226
 227 /*
 228  * Fill dir_slot entries with appropriate name, id, and attr
 229  * 'itr' will point to a next entry
 230  */
 231 static int
 232 fill_dir_slot(fat_itr *itr, const char *l_name)
 233 {
 234         __u8 temp_dir_slot_buffer[MAX_LFN_SLOT * sizeof(dir_slot)];
 235         dir_slot *slotptr = (dir_slot *)temp_dir_slot_buffer;
 236         __u8 counter = 0, checksum;
 237         int idx = 0, ret;
 238
 239         /* Get short file name checksum value */
 240         checksum = mkcksum(itr->dent->name, itr->dent->ext);
 241
 242         do {
 243                 memset(slotptr, 0x00, sizeof(dir_slot));
 244                 ret = str2slot(slotptr, l_name, &idx);
 245                 slotptr->id = ++counter;
 246                 slotptr->attr = ATTR_VFAT;
 247                 slotptr->alias_checksum = checksum;
 248                 slotptr++;
 249         } while (ret == 0);
 250
 251         slotptr--;
 252         slotptr->id |= LAST_LONG_ENTRY_MASK;
 253
 254         while (counter >= 1) {
 255                 memcpy(itr->dent, slotptr, sizeof(dir_slot));
 256                 slotptr--;
 257                 counter--;
 258
 259                 if (itr->remaining == 0)
 260                         flush_dir(itr);
 261
 262                 /* allocate a cluster for more entries */
 263                 if (!fat_itr_next(itr))
 264                         if (!itr->dent &&
 265                             (!itr->is_root || itr->fsdata->fatsize == 32) &&
 266                             new_dir_table(itr))
 267                                 return -1;
 268         }
 269
 270         return 0;
 271 }
 272
 273 /*
 274  * Set the entry at index 'entry' in a FAT (12/16/32) table.
 275  */
 276 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 277 {
 278         __u32 bufnum, offset, off16;
 279         __u16 val1, val2;
 280
 281         switch (mydata->fatsize) {
 282         case 32:
 283                 bufnum = entry / FAT32BUFSIZE;
 284                 offset = entry - bufnum * FAT32BUFSIZE;
 285                 break;
 286         case 16:
 287                 bufnum = entry / FAT16BUFSIZE;
 288                 offset = entry - bufnum * FAT16BUFSIZE;
 289                 break;
 290         case 12:
 291                 bufnum = entry / FAT12BUFSIZE;
 292                 offset = entry - bufnum * FAT12BUFSIZE;
 293                 break;
 294         default:
 295                 /* Unsupported FAT size */
 296                 return -1;
 297         }
 298
 299         /* Read a new block of FAT entries into the cache. */
 300         if (bufnum != mydata->fatbufnum) {
 301                 int getsize = FATBUFBLOCKS;
 302                 __u8 *bufptr = mydata->fatbuf;
 303                 __u32 fatlength = mydata->fatlength;
 304                 __u32 startblock = bufnum * FATBUFBLOCKS;
 305
 306                 /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 307                 if (startblock + getsize > fatlength)
 308                         getsize = fatlength - startblock;
 309
 310                 if (flush_dirty_fat_buffer(mydata) < 0)
 311                         return -1;
 312
 313                 startblock += mydata->fat_sect;
 314
 315                 if (disk_read(startblock, getsize, bufptr) < 0) {
 316                         debug("Error reading FAT blocks\n");
 317                         return -1;
 318                 }
 319                 mydata->fatbufnum = bufnum;
 320         }
 321
 322         /* Mark as dirty */
 323         mydata->fat_dirty = 1;
 324
 325         /* Set the actual entry */
 326         switch (mydata->fatsize) {
 327         case 32:
 328                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 329                 break;
 330         case 16:
 331                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 332                 break;
 333         case 12:
 334                 off16 = (offset * 3) / 4;
 335
 336                 switch (offset & 0x3) {
 337                 case 0:
 338                         val1 = cpu_to_le16(entry_value) & 0xfff;
 339                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff;
 340                         ((__u16 *)mydata->fatbuf)[off16] |= val1;
 341                         break;
 342                 case 1:
 343                         val1 = cpu_to_le16(entry_value) & 0xf;
 344                         val2 = (cpu_to_le16(entry_value) >> 4) & 0xff;
 345
 346                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xf000;
 347                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 12);
 348
 349                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xff;
 350                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 351                         break;
 352                 case 2:
 353                         val1 = cpu_to_le16(entry_value) & 0xff;
 354                         val2 = (cpu_to_le16(entry_value) >> 8) & 0xf;
 355
 356                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xff00;
 357                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 8);
 358
 359                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xf;
 360                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 361                         break;
 362                 case 3:
 363                         val1 = cpu_to_le16(entry_value) & 0xfff;
 364                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff0;
 365                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 4);
 366                         break;
 367                 default:
 368                         break;
 369                 }
 370
 371                 break;
 372         default:
 373                 return -1;
 374         }
 375
 376         return 0;
 377 }
 378
 379 /*
 380  * Determine the next free cluster after 'entry' in a FAT (12/16/32) table
 381  * and link it to 'entry'. EOC marker is not set on returned entry.
 382  */
 383 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 384 {
 385         __u32 next_fat, next_entry = entry + 1;
 386
 387         while (1) {
 388                 next_fat = get_fatent(mydata, next_entry);
 389                 if (next_fat == 0) {
 390                         /* found free entry, link to entry */
 391                         set_fatent_value(mydata, entry, next_entry);
 392                         break;
 393                 }
 394                 next_entry++;
 395         }
 396         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 397                mydata->fatsize, entry, next_entry);
 398
 399         return next_entry;
 400 }
 401
 402 /**
 403  * set_sectors() - write data to sectors
 404  *
 405  * Write 'size' bytes from 'buffer' into the specified sector.
 406  *
 407  * @mydata:     data to be written
 408  * @startsect:  sector to be written to
 409  * @buffer:     data to be written
 410  * @size:       bytes to be written (but not more than the size of a cluster)
 411  * Return:      0 on success, -1 otherwise
 412  */
 413 static int
 414 set_sectors(fsdata *mydata, u32 startsect, u8 *buffer, u32 size)
 415 {
 416         u32 nsects = 0;
 417         int ret;
 418
 419         debug("startsect: %d\n", startsect);
 420
 421         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 422                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 423
 424                 debug("FAT: Misaligned buffer address (%p)\n", buffer);
 425
 426                 while (size >= mydata->sect_size) {
 427                         memcpy(tmpbuf, buffer, mydata->sect_size);
 428                         ret = disk_write(startsect++, 1, tmpbuf);
 429                         if (ret != 1) {
 430                                 debug("Error writing data (got %d)\n", ret);
 431                                 return -1;
 432                         }
 433
 434                         buffer += mydata->sect_size;
 435                         size -= mydata->sect_size;
 436                 }
 437         } else if (size >= mydata->sect_size) {
 438                 nsects = size / mydata->sect_size;
 439                 ret = disk_write(startsect, nsects, buffer);
 440                 if (ret != nsects) {
 441                         debug("Error writing data (got %d)\n", ret);
 442                         return -1;
 443                 }
 444
 445                 startsect += nsects;
 446                 buffer += nsects * mydata->sect_size;
 447                 size -= nsects * mydata->sect_size;
 448         }
 449
 450         if (size) {
 451                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 452                 /* Do not leak content of stack */
 453                 memset(tmpbuf, 0, mydata->sect_size);
 454                 memcpy(tmpbuf, buffer, size);
 455                 ret = disk_write(startsect, 1, tmpbuf);
 456                 if (ret != 1) {
 457                         debug("Error writing data (got %d)\n", ret);
 458                         return -1;
 459                 }
 460         }
 461
 462         return 0;
 463 }
 464
 465 /**
 466  * set_cluster() - write data to cluster
 467  *
 468  * Write 'size' bytes from 'buffer' into the specified cluster.
 469  *
 470  * @mydata:     data to be written
 471  * @clustnum:   cluster to be written to
 472  * @buffer:     data to be written
 473  * @size:       bytes to be written (but not more than the size of a cluster)
 474  * Return:      0 on success, -1 otherwise
 475  */
 476 static int
 477 set_cluster(fsdata *mydata, u32 clustnum, u8 *buffer, u32 size)
 478 {
 479         return set_sectors(mydata, clust_to_sect(mydata, clustnum),
 480                            buffer, size);
 481 }
 482
 483 static int
 484 flush_dir(fat_itr *itr)
 485 {
 486         fsdata *mydata = itr->fsdata;
 487         u32 startsect, sect_offset, nsects;
 488
 489         if (!itr->is_root || mydata->fatsize == 32)
 490                 return set_cluster(mydata, itr->clust, itr->block,
 491                                    mydata->clust_size * mydata->sect_size);
 492
 493         sect_offset = itr->clust * mydata->clust_size;
 494         startsect = mydata->rootdir_sect + sect_offset;
 495         /* do not write past the end of rootdir */
 496         nsects = min_t(u32, mydata->clust_size,
 497                        mydata->rootdir_size - sect_offset);
 498
 499         return set_sectors(mydata, startsect, itr->block,
 500                            nsects * mydata->sect_size);
 501 }
 502
 503 /*
 504  * Read and modify data on existing and consecutive cluster blocks
 505  */
 506 static int
 507 get_set_cluster(fsdata *mydata, __u32 clustnum, loff_t pos, __u8 *buffer,
 508                 loff_t size, loff_t *gotsize)
 509 {
 510         static u8 *tmpbuf_cluster;
 511         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 512         __u32 startsect;
 513         loff_t wsize;
 514         int clustcount, i, ret;
 515
 516         *gotsize = 0;
 517         if (!size)
 518                 return 0;
 519
 520         if (!tmpbuf_cluster) {
 521                 tmpbuf_cluster = memalign(ARCH_DMA_MINALIGN, MAX_CLUSTSIZE);
 522                 if (!tmpbuf_cluster)
 523                         return -1;
 524         }
 525
 526         assert(pos < bytesperclust);
 527         startsect = clust_to_sect(mydata, clustnum);
 528
 529         debug("clustnum: %d, startsect: %d, pos: %lld\n",
 530               clustnum, startsect, pos);
 531
 532         /* partial write at beginning */
 533         if (pos) {
 534                 wsize = min(bytesperclust - pos, size);
 535                 ret = disk_read(startsect, mydata->clust_size, tmpbuf_cluster);
 536                 if (ret != mydata->clust_size) {
 537                         debug("Error reading data (got %d)\n", ret);
 538                         return -1;
 539                 }
 540
 541                 memcpy(tmpbuf_cluster + pos, buffer, wsize);
 542                 ret = disk_write(startsect, mydata->clust_size, tmpbuf_cluster);
 543                 if (ret != mydata->clust_size) {
 544                         debug("Error writing data (got %d)\n", ret);
 545                         return -1;
 546                 }
 547
 548                 size -= wsize;
 549                 buffer += wsize;
 550                 *gotsize += wsize;
 551
 552                 startsect += mydata->clust_size;
 553
 554                 if (!size)
 555                         return 0;
 556         }
 557
 558         /* full-cluster write */
 559         if (size >= bytesperclust) {
 560                 clustcount = lldiv(size, bytesperclust);
 561
 562                 if (!((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1))) {
 563                         wsize = clustcount * bytesperclust;
 564                         ret = disk_write(startsect,
 565                                          clustcount * mydata->clust_size,
 566                                          buffer);
 567                         if (ret != clustcount * mydata->clust_size) {
 568                                 debug("Error writing data (got %d)\n", ret);
 569                                 return -1;
 570                         }
 571
 572                         size -= wsize;
 573                         buffer += wsize;
 574                         *gotsize += wsize;
 575
 576                         startsect += clustcount * mydata->clust_size;
 577                 } else {
 578                         for (i = 0; i < clustcount; i++) {
 579                                 memcpy(tmpbuf_cluster, buffer, bytesperclust);
 580                                 ret = disk_write(startsect,
 581                                                  mydata->clust_size,
 582                                                  tmpbuf_cluster);
 583                                 if (ret != mydata->clust_size) {
 584                                         debug("Error writing data (got %d)\n",
 585                                               ret);
 586                                         return -1;
 587                                 }
 588
 589                                 size -= bytesperclust;
 590                                 buffer += bytesperclust;
 591                                 *gotsize += bytesperclust;
 592
 593                                 startsect += mydata->clust_size;
 594                         }
 595                 }
 596         }
 597
 598         /* partial write at end */
 599         if (size) {
 600                 wsize = size;
 601                 ret = disk_read(startsect, mydata->clust_size, tmpbuf_cluster);
 602                 if (ret != mydata->clust_size) {
 603                         debug("Error reading data (got %d)\n", ret);
 604                         return -1;
 605                 }
 606                 memcpy(tmpbuf_cluster, buffer, wsize);
 607                 ret = disk_write(startsect, mydata->clust_size, tmpbuf_cluster);
 608                 if (ret != mydata->clust_size) {
 609                         debug("Error writing data (got %d)\n", ret);
 610                         return -1;
 611                 }
 612
 613                 size -= wsize;
 614                 buffer += wsize;
 615                 *gotsize += wsize;
 616         }
 617
 618         assert(!size);
 619
 620         return 0;
 621 }
 622
 623 /*
 624  * Find the first empty cluster
 625  */
 626 static int find_empty_cluster(fsdata *mydata)
 627 {
 628         __u32 fat_val, entry = 3;
 629
 630         while (1) {
 631                 fat_val = get_fatent(mydata, entry);
 632                 if (fat_val == 0)
 633                         break;
 634                 entry++;
 635         }
 636
 637         return entry;
 638 }
 639
 640 /*
 641  * Allocate a cluster for additional directory entries
 642  */
 643 static int new_dir_table(fat_itr *itr)
 644 {
 645         fsdata *mydata = itr->fsdata;
 646         int dir_newclust = 0;
 647         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 648
 649         dir_newclust = find_empty_cluster(mydata);
 650         set_fatent_value(mydata, itr->clust, dir_newclust);
 651         if (mydata->fatsize == 32)
 652                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 653         else if (mydata->fatsize == 16)
 654                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 655         else if (mydata->fatsize == 12)
 656                 set_fatent_value(mydata, dir_newclust, 0xff8);
 657
 658         itr->clust = dir_newclust;
 659         itr->next_clust = dir_newclust;
 660
 661         if (flush_dirty_fat_buffer(mydata) < 0)
 662                 return -1;
 663
 664         memset(itr->block, 0x00, bytesperclust);
 665
 666         itr->dent = (dir_entry *)itr->block;
 667         itr->last_cluster = 1;
 668         itr->remaining = bytesperclust / sizeof(dir_entry) - 1;
 669
 670         return 0;
 671 }
 672
 673 /*
 674  * Set empty cluster from 'entry' to the end of a file
 675  */
 676 static int clear_fatent(fsdata *mydata, __u32 entry)
 677 {
 678         __u32 fat_val;
 679
 680         while (!CHECK_CLUST(entry, mydata->fatsize)) {
 681                 fat_val = get_fatent(mydata, entry);
 682                 if (fat_val != 0)
 683                         set_fatent_value(mydata, entry, 0);
 684                 else
 685                         break;
 686
 687                 entry = fat_val;
 688         }
 689
 690         /* Flush fat buffer */
 691         if (flush_dirty_fat_buffer(mydata) < 0)
 692                 return -1;
 693
 694         return 0;
 695 }
 696
 697 /*
 698  * Set start cluster in directory entry
 699  */
 700 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 701                               __u32 start_cluster)
 702 {
 703         if (mydata->fatsize == 32)
 704                 dentptr->starthi =
 705                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 706         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 707 }
 708
 709 /*
 710  * Check whether adding a file makes the file system to
 711  * exceed the size of the block device
 712  * Return -1 when overflow occurs, otherwise return 0
 713  */
 714 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 715 {
 716         __u32 startsect, sect_num, offset;
 717
 718         if (clustnum > 0)
 719                 startsect = clust_to_sect(mydata, clustnum);
 720         else
 721                 startsect = mydata->rootdir_sect;
 722
 723         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 724
 725         if (offset != 0)
 726                 sect_num++;
 727
 728         if (startsect + sect_num > total_sector)
 729                 return -1;
 730         return 0;
 731 }
 732
 733 /*
 734  * Write at most 'maxsize' bytes from 'buffer' into
 735  * the file associated with 'dentptr'
 736  * Update the number of bytes written in *gotsize and return 0
 737  * or return -1 on fatal errors.
 738  */
 739 static int
 740 set_contents(fsdata *mydata, dir_entry *dentptr, loff_t pos, __u8 *buffer,
 741              loff_t maxsize, loff_t *gotsize)
 742 {
 743         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 744         __u32 curclust = START(dentptr);
 745         __u32 endclust = 0, newclust = 0;
 746         u64 cur_pos, filesize;
 747         loff_t offset, actsize, wsize;
 748
 749         *gotsize = 0;
 750         filesize = pos + maxsize;
 751
 752         debug("%llu bytes\n", filesize);
 753
 754         if (!filesize) {
 755                 if (!curclust)
 756                         return 0;
 757                 if (!CHECK_CLUST(curclust, mydata->fatsize) ||
 758                     IS_LAST_CLUST(curclust, mydata->fatsize)) {
 759                         clear_fatent(mydata, curclust);
 760                         set_start_cluster(mydata, dentptr, 0);
 761                         return 0;
 762                 }
 763                 debug("curclust: 0x%x\n", curclust);
 764                 debug("Invalid FAT entry\n");
 765                 return -1;
 766         }
 767
 768         if (!curclust) {
 769                 assert(pos == 0);
 770                 goto set_clusters;
 771         }
 772
 773         /* go to cluster at pos */
 774         cur_pos = bytesperclust;
 775         while (1) {
 776                 if (pos <= cur_pos)
 777                         break;
 778                 if (IS_LAST_CLUST(curclust, mydata->fatsize))
 779                         break;
 780
 781                 newclust = get_fatent(mydata, curclust);
 782                 if (!IS_LAST_CLUST(newclust, mydata->fatsize) &&
 783                     CHECK_CLUST(newclust, mydata->fatsize)) {
 784                         debug("curclust: 0x%x\n", curclust);
 785                         debug("Invalid FAT entry\n");
 786                         return -1;
 787                 }
 788
 789                 cur_pos += bytesperclust;
 790                 curclust = newclust;
 791         }
 792         if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 793                 assert(pos == cur_pos);
 794                 goto set_clusters;
 795         }
 796
 797         assert(pos < cur_pos);
 798         cur_pos -= bytesperclust;
 799
 800         /* overwrite */
 801         assert(IS_LAST_CLUST(curclust, mydata->fatsize) ||
 802                !CHECK_CLUST(curclust, mydata->fatsize));
 803
 804         while (1) {
 805                 /* search for allocated consecutive clusters */
 806                 actsize = bytesperclust;
 807                 endclust = curclust;
 808                 while (1) {
 809                         if (filesize <= (cur_pos + actsize))
 810                                 break;
 811
 812                         newclust = get_fatent(mydata, endclust);
 813
 814                         if (newclust != endclust + 1)
 815                                 break;
 816                         if (IS_LAST_CLUST(newclust, mydata->fatsize))
 817                                 break;
 818                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 819                                 debug("curclust: 0x%x\n", curclust);
 820                                 debug("Invalid FAT entry\n");
 821                                 return -1;
 822                         }
 823
 824                         actsize += bytesperclust;
 825                         endclust = newclust;
 826                 }
 827
 828                 /* overwrite to <curclust..endclust> */
 829                 if (pos < cur_pos)
 830                         offset = 0;
 831                 else
 832                         offset = pos - cur_pos;
 833                 wsize = min_t(unsigned long long, actsize, filesize - cur_pos);
 834                 wsize -= offset;
 835
 836                 if (get_set_cluster(mydata, curclust, offset,
 837                                     buffer, wsize, &actsize)) {
 838                         printf("Error get-and-setting cluster\n");
 839                         return -1;
 840                 }
 841                 buffer += wsize;
 842                 *gotsize += wsize;
 843                 cur_pos += offset + wsize;
 844
 845                 if (filesize <= cur_pos)
 846                         break;
 847
 848                 if (IS_LAST_CLUST(newclust, mydata->fatsize))
 849                         /* no more clusters */
 850                         break;
 851
 852                 curclust = newclust;
 853         }
 854
 855         if (filesize <= cur_pos) {
 856                 /* no more write */
 857                 newclust = get_fatent(mydata, endclust);
 858                 if (!IS_LAST_CLUST(newclust, mydata->fatsize)) {
 859                         /* truncate the rest */
 860                         clear_fatent(mydata, newclust);
 861
 862                         /* Mark end of file in FAT */
 863                         if (mydata->fatsize == 12)
 864                                 newclust = 0xfff;
 865                         else if (mydata->fatsize == 16)
 866                                 newclust = 0xffff;
 867                         else if (mydata->fatsize == 32)
 868                                 newclust = 0xfffffff;
 869                         set_fatent_value(mydata, endclust, newclust);
 870                 }
 871
 872                 return 0;
 873         }
 874
 875         curclust = endclust;
 876         filesize -= cur_pos;
 877         assert(!do_div(cur_pos, bytesperclust));
 878
 879 set_clusters:
 880         /* allocate and write */
 881         assert(!pos);
 882
 883         /* Assure that curclust is valid */
 884         if (!curclust) {
 885                 curclust = find_empty_cluster(mydata);
 886                 set_start_cluster(mydata, dentptr, curclust);
 887         } else {
 888                 newclust = get_fatent(mydata, curclust);
 889
 890                 if (IS_LAST_CLUST(newclust, mydata->fatsize)) {
 891                         newclust = determine_fatent(mydata, curclust);
 892                         set_fatent_value(mydata, curclust, newclust);
 893                         curclust = newclust;
 894                 } else {
 895                         debug("error: something wrong\n");
 896                         return -1;
 897                 }
 898         }
 899
 900         /* TODO: already partially written */
 901         if (check_overflow(mydata, curclust, filesize)) {
 902                 printf("Error: no space left: %llu\n", filesize);
 903                 return -1;
 904         }
 905
 906         actsize = bytesperclust;
 907         endclust = curclust;
 908         do {
 909                 /* search for consecutive clusters */
 910                 while (actsize < filesize) {
 911                         newclust = determine_fatent(mydata, endclust);
 912
 913                         if ((newclust - 1) != endclust)
 914                                 /* write to <curclust..endclust> */
 915                                 goto getit;
 916
 917                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 918                                 debug("newclust: 0x%x\n", newclust);
 919                                 debug("Invalid FAT entry\n");
 920                                 return 0;
 921                         }
 922                         endclust = newclust;
 923                         actsize += bytesperclust;
 924                 }
 925
 926                 /* set remaining bytes */
 927                 actsize = filesize;
 928                 if (set_cluster(mydata, curclust, buffer, (u32)actsize) != 0) {
 929                         debug("error: writing cluster\n");
 930                         return -1;
 931                 }
 932                 *gotsize += actsize;
 933
 934                 /* Mark end of file in FAT */
 935                 if (mydata->fatsize == 12)
 936                         newclust = 0xfff;
 937                 else if (mydata->fatsize == 16)
 938                         newclust = 0xffff;
 939                 else if (mydata->fatsize == 32)
 940                         newclust = 0xfffffff;
 941                 set_fatent_value(mydata, endclust, newclust);
 942
 943                 return 0;
 944 getit:
 945                 if (set_cluster(mydata, curclust, buffer, (u32)actsize) != 0) {
 946                         debug("error: writing cluster\n");
 947                         return -1;
 948                 }
 949                 *gotsize += actsize;
 950                 filesize -= actsize;
 951                 buffer += actsize;
 952
 953                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 954                         debug("newclust: 0x%x\n", newclust);
 955                         debug("Invalid FAT entry\n");
 956                         return 0;
 957                 }
 958                 actsize = bytesperclust;
 959                 curclust = endclust = newclust;
 960         } while (1);
 961
 962         return 0;
 963 }
 964
 965 /*
 966  * Fill dir_entry
 967  */
 968 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 969         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 970 {
 971         set_start_cluster(mydata, dentptr, start_cluster);
 972         dentptr->size = cpu_to_le32(size);
 973
 974         dentptr->attr = attr;
 975
 976         set_name(dentptr, filename);
 977 }
 978
 979 /*
 980  * Find a directory entry based on filename or start cluster number
 981  * If the directory entry is not found,
 982  * the new position for writing a directory entry will be returned
 983  */
 984 static dir_entry *find_directory_entry(fat_itr *itr, char *filename)
 985 {
 986         int match = 0;
 987
 988         while (fat_itr_next(itr)) {
 989                 /* check both long and short name: */
 990                 if (!strcasecmp(filename, itr->name))
 991                         match = 1;
 992                 else if (itr->name != itr->s_name &&
 993                          !strcasecmp(filename, itr->s_name))
 994                         match = 1;
 995
 996                 if (!match)
 997                         continue;
 998
 999                 if (itr->dent->name[0] == '\0')
1000                         return NULL;
1001                 else
1002                         return itr->dent;
1003         }
1004
1005         /* allocate a cluster for more entries */
1006         if (!itr->dent &&
1007             (!itr->is_root || itr->fsdata->fatsize == 32) &&
1008             new_dir_table(itr))
1009                 /* indicate that allocating dent failed */
1010                 itr->dent = NULL;
1011
1012         return NULL;
1013 }
1014
1015 static int split_filename(char *filename, char **dirname, char **basename)
1016 {
1017         char *p, *last_slash, *last_slash_cont;
1018
1019 again:
1020         p = filename;
1021         last_slash = NULL;
1022         last_slash_cont = NULL;
1023         while (*p) {
1024                 if (ISDIRDELIM(*p)) {
1025                         last_slash = p;
1026                         last_slash_cont = p;
1027                         /* continuous slashes */
1028                         while (ISDIRDELIM(*p))
1029                                 last_slash_cont = p++;
1030                         if (!*p)
1031                                 break;
1032                 }
1033                 p++;
1034         }
1035
1036         if (last_slash) {
1037                 if (last_slash_cont == (filename + strlen(filename) - 1)) {
1038                         /* remove trailing slashes */
1039                         *last_slash = '\0';
1040                         goto again;
1041                 }
1042
1043                 if (last_slash == filename) {
1044                         /* avoid ""(null) directory */
1045                         *dirname = "/";
1046                 } else {
1047                         *last_slash = '\0';
1048                         *dirname = filename;
1049                 }
1050
1051                 *last_slash_cont = '\0';
1052                 *basename = last_slash_cont + 1;
1053         } else {
1054                 *dirname = "/"; /* root by default */
1055                 *basename = filename;
1056         }
1057
1058         return 0;
1059 }
1060
1061 /**
1062  * normalize_longname() - check long file name and convert to lower case
1063  *
1064  * We assume here that the FAT file system is using an 8bit code page.
1065  * Linux typically uses CP437, EDK2 assumes CP1250.
1066  *
1067  * @l_filename: preallocated buffer receiving the normalized name
1068  * @filename:   filename to normalize
1069  * Return:      0 on success, -1 on failure
1070  */
1071 static int normalize_longname(char *l_filename, const char *filename)
1072 {
1073         const char *p, illegal[] = "<>:\"/\\|?*";
1074
1075         if (strlen(filename) >= VFAT_MAXLEN_BYTES)
1076                 return -1;
1077
1078         for (p = filename; *p; ++p) {
1079                 if ((unsigned char)*p < 0x20)
1080                         return -1;
1081                 if (strchr(illegal, *p))
1082                         return -1;
1083         }
1084
1085         strcpy(l_filename, filename);
1086         downcase(l_filename, VFAT_MAXLEN_BYTES);
1087
1088         return 0;
1089 }
1090
1091 int file_fat_write_at(const char *filename, loff_t pos, void *buffer,
1092                       loff_t size, loff_t *actwrite)
1093 {
1094         dir_entry *retdent;
1095         fsdata datablock = { .fatbuf = NULL, };
1096         fsdata *mydata = &datablock;
1097         fat_itr *itr = NULL;
1098         int ret = -1;
1099         char *filename_copy, *parent, *basename;
1100         char l_filename[VFAT_MAXLEN_BYTES];
1101
1102         debug("writing %s\n", filename);
1103
1104         filename_copy = strdup(filename);
1105         if (!filename_copy)
1106                 return -ENOMEM;
1107
1108         split_filename(filename_copy, &parent, &basename);
1109         if (!strlen(basename)) {
1110                 ret = -EINVAL;
1111                 goto exit;
1112         }
1113
1114         filename = basename;
1115         if (normalize_longname(l_filename, filename)) {
1116                 printf("FAT: illegal filename (%s)\n", filename);
1117                 ret = -EINVAL;
1118                 goto exit;
1119         }
1120
1121         itr = malloc_cache_aligned(sizeof(fat_itr));
1122         if (!itr) {
1123                 ret = -ENOMEM;
1124                 goto exit;
1125         }
1126
1127         ret = fat_itr_root(itr, &datablock);
1128         if (ret)
1129                 goto exit;
1130
1131         total_sector = datablock.total_sect;
1132
1133         ret = fat_itr_resolve(itr, parent, TYPE_DIR);
1134         if (ret) {
1135                 printf("%s: doesn't exist (%d)\n", parent, ret);
1136                 goto exit;
1137         }
1138
1139         retdent = find_directory_entry(itr, l_filename);
1140
1141         if (retdent) {
1142                 if (fat_itr_isdir(itr)) {
1143                         ret = -EISDIR;
1144                         goto exit;
1145                 }
1146
1147                 /* A file exists */
1148                 if (pos == -1)
1149                         /* Append to the end */
1150                         pos = FAT2CPU32(retdent->size);
1151                 if (pos > retdent->size) {
1152                         /* No hole allowed */
1153                         ret = -EINVAL;
1154                         goto exit;
1155                 }
1156
1157                 /* Update file size in a directory entry */
1158                 retdent->size = cpu_to_le32(pos + size);
1159         } else {
1160                 /* Create a new file */
1161
1162                 if (itr->is_root) {
1163                         /* root dir cannot have "." or ".." */
1164                         if (!strcmp(l_filename, ".") ||
1165                             !strcmp(l_filename, "..")) {
1166                                 ret = -EINVAL;
1167                                 goto exit;
1168                         }
1169                 }
1170
1171                 if (!itr->dent) {
1172                         printf("Error: allocating new dir entry\n");
1173                         ret = -EIO;
1174                         goto exit;
1175                 }
1176
1177                 if (pos) {
1178                         /* No hole allowed */
1179                         ret = -EINVAL;
1180                         goto exit;
1181                 }
1182
1183                 memset(itr->dent, 0, sizeof(*itr->dent));
1184
1185                 /* Calculate checksum for short name */
1186                 set_name(itr->dent, filename);
1187
1188                 /* Set long name entries */
1189                 if (fill_dir_slot(itr, filename)) {
1190                         ret = -EIO;
1191                         goto exit;
1192                 }
1193
1194                 /* Set short name entry */
1195                 fill_dentry(itr->fsdata, itr->dent, filename, 0, size, 0x20);
1196
1197                 retdent = itr->dent;
1198         }
1199
1200         ret = set_contents(mydata, retdent, pos, buffer, size, actwrite);
1201         if (ret < 0) {
1202                 printf("Error: writing contents\n");
1203                 ret = -EIO;
1204                 goto exit;
1205         }
1206         debug("attempt to write 0x%llx bytes\n", *actwrite);
1207
1208         /* Flush fat buffer */
1209         ret = flush_dirty_fat_buffer(mydata);
1210         if (ret) {
1211                 printf("Error: flush fat buffer\n");
1212                 ret = -EIO;
1213                 goto exit;
1214         }
1215
1216         /* Write directory table to device */
1217         ret = flush_dir(itr);
1218         if (ret) {
1219                 printf("Error: writing directory entry\n");
1220                 ret = -EIO;
1221         }
1222
1223 exit:
1224         free(filename_copy);
1225         free(mydata->fatbuf);
1226         free(itr);
1227         return ret;
1228 }
1229
1230 int file_fat_write(const char *filename, void *buffer, loff_t offset,
1231                    loff_t maxsize, loff_t *actwrite)
1232 {
1233         return file_fat_write_at(filename, offset, buffer, maxsize, actwrite);
1234 }
1235
1236 static int fat_dir_entries(fat_itr *itr)
1237 {
1238         fat_itr *dirs;
1239         fsdata fsdata = { .fatbuf = NULL, }, *mydata = &fsdata;
1240                                                 /* for FATBUFSIZE */
1241         int count;
1242
1243         dirs = malloc_cache_aligned(sizeof(fat_itr));
1244         if (!dirs) {
1245                 debug("Error: allocating memory\n");
1246                 count = -ENOMEM;
1247                 goto exit;
1248         }
1249
1250         /* duplicate fsdata */
1251         fat_itr_child(dirs, itr);
1252         fsdata = *dirs->fsdata;
1253
1254         /* allocate local fat buffer */
1255         fsdata.fatbuf = malloc_cache_aligned(FATBUFSIZE);
1256         if (!fsdata.fatbuf) {
1257                 debug("Error: allocating memory\n");
1258                 count = -ENOMEM;
1259                 goto exit;
1260         }
1261         fsdata.fatbufnum = -1;
1262         dirs->fsdata = &fsdata;
1263
1264         for (count = 0; fat_itr_next(dirs); count++)
1265                 ;
1266
1267 exit:
1268         free(fsdata.fatbuf);
1269         free(dirs);
1270         return count;
1271 }
1272
1273 static int delete_dentry(fat_itr *itr)
1274 {
1275         fsdata *mydata = itr->fsdata;
1276         dir_entry *dentptr = itr->dent;
1277
1278         /* free cluster blocks */
1279         clear_fatent(mydata, START(dentptr));
1280         if (flush_dirty_fat_buffer(mydata) < 0) {
1281                 printf("Error: flush fat buffer\n");
1282                 return -EIO;
1283         }
1284
1285         /*
1286          * update a directory entry
1287          * TODO:
1288          *  - long file name support
1289          *  - find and mark the "new" first invalid entry as name[0]=0x00
1290          */
1291         memset(dentptr, 0, sizeof(*dentptr));
1292         dentptr->name[0] = 0xe5;
1293
1294         if (flush_dir(itr)) {
1295                 printf("error: writing directory entry\n");
1296                 return -EIO;
1297         }
1298
1299         return 0;
1300 }
1301
1302 int fat_unlink(const char *filename)
1303 {
1304         fsdata fsdata = { .fatbuf = NULL, };
1305         fat_itr *itr = NULL;
1306         int n_entries, ret;
1307         char *filename_copy, *dirname, *basename;
1308
1309         filename_copy = strdup(filename);
1310         if (!filename_copy) {
1311                 printf("Error: allocating memory\n");
1312                 ret = -ENOMEM;
1313                 goto exit;
1314         }
1315         split_filename(filename_copy, &dirname, &basename);
1316
1317         if (!strcmp(dirname, "/") && !strcmp(basename, "")) {
1318                 printf("Error: cannot remove root\n");
1319                 ret = -EINVAL;
1320                 goto exit;
1321         }
1322
1323         itr = malloc_cache_aligned(sizeof(fat_itr));
1324         if (!itr) {
1325                 printf("Error: allocating memory\n");
1326                 ret = -ENOMEM;
1327                 goto exit;
1328         }
1329
1330         ret = fat_itr_root(itr, &fsdata);
1331         if (ret)
1332                 goto exit;
1333
1334         total_sector = fsdata.total_sect;
1335
1336         ret = fat_itr_resolve(itr, dirname, TYPE_DIR);
1337         if (ret) {
1338                 printf("%s: doesn't exist (%d)\n", dirname, ret);
1339                 ret = -ENOENT;
1340                 goto exit;
1341         }
1342
1343         if (!find_directory_entry(itr, basename)) {
1344                 printf("%s: doesn't exist\n", basename);
1345                 ret = -ENOENT;
1346                 goto exit;
1347         }
1348
1349         if (fat_itr_isdir(itr)) {
1350                 n_entries = fat_dir_entries(itr);
1351                 if (n_entries < 0) {
1352                         ret = n_entries;
1353                         goto exit;
1354                 }
1355                 if (n_entries > 2) {
1356                         printf("Error: directory is not empty: %d\n",
1357                                n_entries);
1358                         ret = -EINVAL;
1359                         goto exit;
1360                 }
1361         }
1362
1363         ret = delete_dentry(itr);
1364
1365 exit:
1366         free(fsdata.fatbuf);
1367         free(itr);
1368         free(filename_copy);
1369
1370         return ret;
1371 }
1372
1373 int fat_mkdir(const char *new_dirname)
1374 {
1375         dir_entry *retdent;
1376         fsdata datablock = { .fatbuf = NULL, };
1377         fsdata *mydata = &datablock;
1378         fat_itr *itr = NULL;
1379         char *dirname_copy, *parent, *dirname;
1380         char l_dirname[VFAT_MAXLEN_BYTES];
1381         int ret = -1;
1382         loff_t actwrite;
1383         unsigned int bytesperclust;
1384         dir_entry *dotdent = NULL;
1385
1386         dirname_copy = strdup(new_dirname);
1387         if (!dirname_copy)
1388                 goto exit;
1389
1390         split_filename(dirname_copy, &parent, &dirname);
1391         if (!strlen(dirname)) {
1392                 ret = -EINVAL;
1393                 goto exit;
1394         }
1395
1396         if (normalize_longname(l_dirname, dirname)) {
1397                 printf("FAT: illegal filename (%s)\n", dirname);
1398                 ret = -EINVAL;
1399                 goto exit;
1400         }
1401
1402         itr = malloc_cache_aligned(sizeof(fat_itr));
1403         if (!itr) {
1404                 ret = -ENOMEM;
1405                 goto exit;
1406         }
1407
1408         ret = fat_itr_root(itr, &datablock);
1409         if (ret)
1410                 goto exit;
1411
1412         total_sector = datablock.total_sect;
1413
1414         ret = fat_itr_resolve(itr, parent, TYPE_DIR);
1415         if (ret) {
1416                 printf("%s: doesn't exist (%d)\n", parent, ret);
1417                 goto exit;
1418         }
1419
1420         retdent = find_directory_entry(itr, l_dirname);
1421
1422         if (retdent) {
1423                 printf("%s: already exists\n", l_dirname);
1424                 ret = -EEXIST;
1425                 goto exit;
1426         } else {
1427                 if (itr->is_root) {
1428                         /* root dir cannot have "." or ".." */
1429                         if (!strcmp(l_dirname, ".") ||
1430                             !strcmp(l_dirname, "..")) {
1431                                 ret = -EINVAL;
1432                                 goto exit;
1433                         }
1434                 }
1435
1436                 if (!itr->dent) {
1437                         printf("Error: allocating new dir entry\n");
1438                         ret = -EIO;
1439                         goto exit;
1440                 }
1441
1442                 memset(itr->dent, 0, sizeof(*itr->dent));
1443
1444                 /* Set short name to set alias checksum field in dir_slot */
1445                 set_name(itr->dent, dirname);
1446                 fill_dir_slot(itr, dirname);
1447
1448                 /* Set attribute as archive for regular file */
1449                 fill_dentry(itr->fsdata, itr->dent, dirname, 0, 0,
1450                             ATTR_DIR | ATTR_ARCH);
1451
1452                 retdent = itr->dent;
1453         }
1454
1455         /* Default entries */
1456         bytesperclust = mydata->clust_size * mydata->sect_size;
1457         dotdent = malloc_cache_aligned(bytesperclust);
1458         if (!dotdent) {
1459                 ret = -ENOMEM;
1460                 goto exit;
1461         }
1462         memset(dotdent, 0, bytesperclust);
1463
1464         memcpy(dotdent[0].name, ".       ", 8);
1465         memcpy(dotdent[0].ext, "   ", 3);
1466         dotdent[0].attr = ATTR_DIR | ATTR_ARCH;
1467
1468         memcpy(dotdent[1].name, "..      ", 8);
1469         memcpy(dotdent[1].ext, "   ", 3);
1470         dotdent[1].attr = ATTR_DIR | ATTR_ARCH;
1471         set_start_cluster(mydata, &dotdent[1], itr->start_clust);
1472
1473         ret = set_contents(mydata, retdent, 0, (__u8 *)dotdent,
1474                            bytesperclust, &actwrite);
1475         if (ret < 0) {
1476                 printf("Error: writing contents\n");
1477                 goto exit;
1478         }
1479         /* Write twice for "." */
1480         set_start_cluster(mydata, &dotdent[0], START(retdent));
1481         ret = set_contents(mydata, retdent, 0, (__u8 *)dotdent,
1482                            bytesperclust, &actwrite);
1483         if (ret < 0) {
1484                 printf("Error: writing contents\n");
1485                 goto exit;
1486         }
1487
1488         /* Flush fat buffer */
1489         ret = flush_dirty_fat_buffer(mydata);
1490         if (ret) {
1491                 printf("Error: flush fat buffer\n");
1492                 goto exit;
1493         }
1494
1495         /* Write directory table to device */
1496         ret = flush_dir(itr);
1497         if (ret)
1498                 printf("Error: writing directory entry\n");
1499
1500 exit:
1501         free(dirname_copy);
1502         free(mydata->fatbuf);
1503         free(itr);
1504         free(dotdent);
1505         return ret;
1506 }