fs/fat/fat_write.c

   1 /*
   2  * fat_write.c
   3  *
   4  * R/W (V)FAT 12/16/32 filesystem implementation by Donggeun Kim
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <common.h>
  10 #include <command.h>
  11 #include <config.h>
  12 #include <fat.h>
  13 #include <asm/byteorder.h>
  14 #include <part.h>
  15 #include <linux/ctype.h>
  16 #include <div64.h>
  17 #include <linux/math64.h>
  18 #include "fat.c"
  19
  20 static void uppercase(char *str, int len)
  21 {
  22         int i;
  23
  24         for (i = 0; i < len; i++) {
  25                 *str = toupper(*str);
  26                 str++;
  27         }
  28 }
  29
  30 static int total_sector;
  31 static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
  32 {
  33         ulong ret;
  34
  35         if (!cur_dev)
  36                 return -1;
  37
  38         if (cur_part_info.start + block + nr_blocks >
  39                 cur_part_info.start + total_sector) {
  40                 printf("error: overflow occurs\n");
  41                 return -1;
  42         }
  43
  44         ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
  45         if (nr_blocks && ret == 0)
  46                 return -1;
  47
  48         return ret;
  49 }
  50
  51 /*
  52  * Set short name in directory entry
  53  */
  54 static void set_name(dir_entry *dirent, const char *filename)
  55 {
  56         char s_name[VFAT_MAXLEN_BYTES];
  57         char *period;
  58         int period_location, len, i, ext_num;
  59
  60         if (filename == NULL)
  61                 return;
  62
  63         len = strlen(filename);
  64         if (len == 0)
  65                 return;
  66
  67         strcpy(s_name, filename);
  68         uppercase(s_name, len);
  69
  70         period = strchr(s_name, '.');
  71         if (period == NULL) {
  72                 period_location = len;
  73                 ext_num = 0;
  74         } else {
  75                 period_location = period - s_name;
  76                 ext_num = len - period_location - 1;
  77         }
  78
  79         /* Pad spaces when the length of file name is shorter than eight */
  80         if (period_location < 8) {
  81                 memcpy(dirent->name, s_name, period_location);
  82                 for (i = period_location; i < 8; i++)
  83                         dirent->name[i] = ' ';
  84         } else if (period_location == 8) {
  85                 memcpy(dirent->name, s_name, period_location);
  86         } else {
  87                 memcpy(dirent->name, s_name, 6);
  88                 dirent->name[6] = '~';
  89                 dirent->name[7] = '1';
  90         }
  91
  92         if (ext_num < 3) {
  93                 memcpy(dirent->ext, s_name + period_location + 1, ext_num);
  94                 for (i = ext_num; i < 3; i++)
  95                         dirent->ext[i] = ' ';
  96         } else
  97                 memcpy(dirent->ext, s_name + period_location + 1, 3);
  98
  99         debug("name : %s\n", dirent->name);
 100         debug("ext : %s\n", dirent->ext);
 101 }
 102
 103 static __u8 num_of_fats;
 104 /*
 105  * Write fat buffer into block device
 106  */
 107 static int flush_dirty_fat_buffer(fsdata *mydata)
 108 {
 109         int getsize = FATBUFBLOCKS;
 110         __u32 fatlength = mydata->fatlength;
 111         __u8 *bufptr = mydata->fatbuf;
 112         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 113
 114         debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
 115               (int)mydata->fat_dirty);
 116
 117         if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
 118                 return 0;
 119
 120         startblock += mydata->fat_sect;
 121
 122         if (getsize > fatlength)
 123                 getsize = fatlength;
 124
 125         /* Write FAT buf */
 126         if (disk_write(startblock, getsize, bufptr) < 0) {
 127                 debug("error: writing FAT blocks\n");
 128                 return -1;
 129         }
 130
 131         if (num_of_fats == 2) {
 132                 /* Update corresponding second FAT blocks */
 133                 startblock += mydata->fatlength;
 134                 if (disk_write(startblock, getsize, bufptr) < 0) {
 135                         debug("error: writing second FAT blocks\n");
 136                         return -1;
 137                 }
 138         }
 139         mydata->fat_dirty = 0;
 140
 141         return 0;
 142 }
 143
 144 /*
 145  * Get the entry at index 'entry' in a FAT (12/16/32) table.
 146  * On failure 0x00 is returned.
 147  * When bufnum is changed, write back the previous fatbuf to the disk.
 148  */
 149 static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
 150 {
 151         __u32 bufnum;
 152         __u32 off16, offset;
 153         __u32 ret = 0x00;
 154         __u16 val1, val2;
 155
 156         if (CHECK_CLUST(entry, mydata->fatsize)) {
 157                 printf("Error: Invalid FAT entry: 0x%08x\n", entry);
 158                 return ret;
 159         }
 160
 161         switch (mydata->fatsize) {
 162         case 32:
 163                 bufnum = entry / FAT32BUFSIZE;
 164                 offset = entry - bufnum * FAT32BUFSIZE;
 165                 break;
 166         case 16:
 167                 bufnum = entry / FAT16BUFSIZE;
 168                 offset = entry - bufnum * FAT16BUFSIZE;
 169                 break;
 170         case 12:
 171                 bufnum = entry / FAT12BUFSIZE;
 172                 offset = entry - bufnum * FAT12BUFSIZE;
 173                 break;
 174
 175         default:
 176                 /* Unsupported FAT size */
 177                 return ret;
 178         }
 179
 180         debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
 181                mydata->fatsize, entry, entry, offset, offset);
 182
 183         /* Read a new block of FAT entries into the cache. */
 184         if (bufnum != mydata->fatbufnum) {
 185                 int getsize = FATBUFBLOCKS;
 186                 __u8 *bufptr = mydata->fatbuf;
 187                 __u32 fatlength = mydata->fatlength;
 188                 __u32 startblock = bufnum * FATBUFBLOCKS;
 189
 190                 if (getsize > fatlength)
 191                         getsize = fatlength;
 192
 193                 startblock += mydata->fat_sect; /* Offset from start of disk */
 194
 195                 /* Write back the fatbuf to the disk */
 196                 if (flush_dirty_fat_buffer(mydata) < 0)
 197                         return -1;
 198
 199                 if (disk_read(startblock, getsize, bufptr) < 0) {
 200                         debug("Error reading FAT blocks\n");
 201                         return ret;
 202                 }
 203                 mydata->fatbufnum = bufnum;
 204         }
 205
 206         /* Get the actual entry from the table */
 207         switch (mydata->fatsize) {
 208         case 32:
 209                 ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
 210                 break;
 211         case 16:
 212                 ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
 213                 break;
 214         case 12:
 215                 off16 = (offset * 3) / 4;
 216
 217                 switch (offset & 0x3) {
 218                 case 0:
 219                         ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
 220                         ret &= 0xfff;
 221                         break;
 222                 case 1:
 223                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 224                         val1 &= 0xf000;
 225                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 226                         val2 &= 0x00ff;
 227                         ret = (val2 << 4) | (val1 >> 12);
 228                         break;
 229                 case 2:
 230                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 231                         val1 &= 0xff00;
 232                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 233                         val2 &= 0x000f;
 234                         ret = (val2 << 8) | (val1 >> 8);
 235                         break;
 236                 case 3:
 237                         ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 238                         ret = (ret & 0xfff0) >> 4;
 239                         break;
 240                 default:
 241                         break;
 242                 }
 243                 break;
 244         }
 245         debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
 246                mydata->fatsize, ret, entry, offset);
 247
 248         return ret;
 249 }
 250
 251 /*
 252  * Set the file name information from 'name' into 'slotptr',
 253  */
 254 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 255 {
 256         int j, end_idx = 0;
 257
 258         for (j = 0; j <= 8; j += 2) {
 259                 if (name[*idx] == 0x00) {
 260                         slotptr->name0_4[j] = 0;
 261                         slotptr->name0_4[j + 1] = 0;
 262                         end_idx++;
 263                         goto name0_4;
 264                 }
 265                 slotptr->name0_4[j] = name[*idx];
 266                 (*idx)++;
 267                 end_idx++;
 268         }
 269         for (j = 0; j <= 10; j += 2) {
 270                 if (name[*idx] == 0x00) {
 271                         slotptr->name5_10[j] = 0;
 272                         slotptr->name5_10[j + 1] = 0;
 273                         end_idx++;
 274                         goto name5_10;
 275                 }
 276                 slotptr->name5_10[j] = name[*idx];
 277                 (*idx)++;
 278                 end_idx++;
 279         }
 280         for (j = 0; j <= 2; j += 2) {
 281                 if (name[*idx] == 0x00) {
 282                         slotptr->name11_12[j] = 0;
 283                         slotptr->name11_12[j + 1] = 0;
 284                         end_idx++;
 285                         goto name11_12;
 286                 }
 287                 slotptr->name11_12[j] = name[*idx];
 288                 (*idx)++;
 289                 end_idx++;
 290         }
 291
 292         if (name[*idx] == 0x00)
 293                 return 1;
 294
 295         return 0;
 296 /* Not used characters are filled with 0xff 0xff */
 297 name0_4:
 298         for (; end_idx < 5; end_idx++) {
 299                 slotptr->name0_4[end_idx * 2] = 0xff;
 300                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 301         }
 302         end_idx = 5;
 303 name5_10:
 304         end_idx -= 5;
 305         for (; end_idx < 6; end_idx++) {
 306                 slotptr->name5_10[end_idx * 2] = 0xff;
 307                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 308         }
 309         end_idx = 11;
 310 name11_12:
 311         end_idx -= 11;
 312         for (; end_idx < 2; end_idx++) {
 313                 slotptr->name11_12[end_idx * 2] = 0xff;
 314                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 315         }
 316
 317         return 1;
 318 }
 319
 320 static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
 321 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);
 322
 323 /*
 324  * Fill dir_slot entries with appropriate name, id, and attr
 325  * The real directory entry is returned by 'dentptr'
 326  */
 327 static void
 328 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 329 {
 330         dir_slot *slotptr = (dir_slot *)get_contents_vfatname_block;
 331         __u8 counter = 0, checksum;
 332         int idx = 0, ret;
 333
 334         /* Get short file name checksum value */
 335         checksum = mkcksum((*dentptr)->name, (*dentptr)->ext);
 336
 337         do {
 338                 memset(slotptr, 0x00, sizeof(dir_slot));
 339                 ret = str2slot(slotptr, l_name, &idx);
 340                 slotptr->id = ++counter;
 341                 slotptr->attr = ATTR_VFAT;
 342                 slotptr->alias_checksum = checksum;
 343                 slotptr++;
 344         } while (ret == 0);
 345
 346         slotptr--;
 347         slotptr->id |= LAST_LONG_ENTRY_MASK;
 348
 349         while (counter >= 1) {
 350                 if (is_next_clust(mydata, *dentptr)) {
 351                         /* A new cluster is allocated for directory table */
 352                         flush_dir_table(mydata, dentptr);
 353                 }
 354                 memcpy(*dentptr, slotptr, sizeof(dir_slot));
 355                 (*dentptr)++;
 356                 slotptr--;
 357                 counter--;
 358         }
 359
 360         if (is_next_clust(mydata, *dentptr)) {
 361                 /* A new cluster is allocated for directory table */
 362                 flush_dir_table(mydata, dentptr);
 363         }
 364 }
 365
 366 static __u32 dir_curclust;
 367
 368 /*
 369  * Extract the full long filename starting at 'retdent' (which is really
 370  * a slot) into 'l_name'. If successful also copy the real directory entry
 371  * into 'retdent'
 372  * If additional adjacent cluster for directory entries is read into memory,
 373  * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and
 374  * the location of the real directory entry is returned by 'retdent'
 375  * Return 0 on success, -1 otherwise.
 376  */
 377 static int
 378 get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 379               dir_entry **retdent, char *l_name)
 380 {
 381         dir_entry *realdent;
 382         dir_slot *slotptr = (dir_slot *)(*retdent);
 383         dir_slot *slotptr2 = NULL;
 384         __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
 385                                                         PREFETCH_BLOCKS :
 386                                                         mydata->clust_size);
 387         __u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
 388         int idx = 0, cur_position = 0;
 389
 390         if (counter > VFAT_MAXSEQ) {
 391                 debug("Error: VFAT name is too long\n");
 392                 return -1;
 393         }
 394
 395         while ((__u8 *)slotptr < buflimit) {
 396                 if (counter == 0)
 397                         break;
 398                 if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
 399                         return -1;
 400                 slotptr++;
 401                 counter--;
 402         }
 403
 404         if ((__u8 *)slotptr >= buflimit) {
 405                 if (curclust == 0)
 406                         return -1;
 407                 curclust = get_fatent_value(mydata, dir_curclust);
 408                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 409                         debug("curclust: 0x%x\n", curclust);
 410                         printf("Invalid FAT entry\n");
 411                         return -1;
 412                 }
 413
 414                 dir_curclust = curclust;
 415
 416                 if (get_cluster(mydata, curclust, get_contents_vfatname_block,
 417                                 mydata->clust_size * mydata->sect_size) != 0) {
 418                         debug("Error: reading directory block\n");
 419                         return -1;
 420                 }
 421
 422                 slotptr2 = (dir_slot *)get_contents_vfatname_block;
 423                 while (counter > 0) {
 424                         if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
 425                             & 0xff) != counter)
 426                                 return -1;
 427                         slotptr2++;
 428                         counter--;
 429                 }
 430
 431                 /* Save the real directory entry */
 432                 realdent = (dir_entry *)slotptr2;
 433                 while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
 434                         slotptr2--;
 435                         slot2str(slotptr2, l_name, &idx);
 436                 }
 437         } else {
 438                 /* Save the real directory entry */
 439                 realdent = (dir_entry *)slotptr;
 440         }
 441
 442         do {
 443                 slotptr--;
 444                 if (slot2str(slotptr, l_name, &idx))
 445                         break;
 446         } while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
 447
 448         l_name[idx] = '\0';
 449         if (*l_name == DELETED_FLAG)
 450                 *l_name = '\0';
 451         else if (*l_name == aRING)
 452                 *l_name = DELETED_FLAG;
 453         downcase(l_name);
 454
 455         /* Return the real directory entry */
 456         *retdent = realdent;
 457
 458         if (slotptr2) {
 459                 memcpy(get_dentfromdir_block, get_contents_vfatname_block,
 460                         mydata->clust_size * mydata->sect_size);
 461                 cur_position = (__u8 *)realdent - get_contents_vfatname_block;
 462                 *retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
 463         }
 464
 465         return 0;
 466 }
 467
 468 /*
 469  * Set the entry at index 'entry' in a FAT (16/32) table.
 470  */
 471 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 472 {
 473         __u32 bufnum, offset;
 474
 475         switch (mydata->fatsize) {
 476         case 32:
 477                 bufnum = entry / FAT32BUFSIZE;
 478                 offset = entry - bufnum * FAT32BUFSIZE;
 479                 break;
 480         case 16:
 481                 bufnum = entry / FAT16BUFSIZE;
 482                 offset = entry - bufnum * FAT16BUFSIZE;
 483                 break;
 484         default:
 485                 /* Unsupported FAT size */
 486                 return -1;
 487         }
 488
 489         /* Read a new block of FAT entries into the cache. */
 490         if (bufnum != mydata->fatbufnum) {
 491                 int getsize = FATBUFBLOCKS;
 492                 __u8 *bufptr = mydata->fatbuf;
 493                 __u32 fatlength = mydata->fatlength;
 494                 __u32 startblock = bufnum * FATBUFBLOCKS;
 495
 496                 fatlength *= mydata->sect_size;
 497                 startblock += mydata->fat_sect;
 498
 499                 if (getsize > fatlength)
 500                         getsize = fatlength;
 501
 502                 if (flush_dirty_fat_buffer(mydata) < 0)
 503                         return -1;
 504
 505                 if (disk_read(startblock, getsize, bufptr) < 0) {
 506                         debug("Error reading FAT blocks\n");
 507                         return -1;
 508                 }
 509                 mydata->fatbufnum = bufnum;
 510         }
 511
 512         /* Mark as dirty */
 513         mydata->fat_dirty = 1;
 514
 515         /* Set the actual entry */
 516         switch (mydata->fatsize) {
 517         case 32:
 518                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 519                 break;
 520         case 16:
 521                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 522                 break;
 523         default:
 524                 return -1;
 525         }
 526
 527         return 0;
 528 }
 529
 530 /*
 531  * Determine the next free cluster after 'entry' in a FAT (16/32) table
 532  * and link it to 'entry'. EOC marker is not set on returned entry.
 533  */
 534 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 535 {
 536         __u32 next_fat, next_entry = entry + 1;
 537
 538         while (1) {
 539                 next_fat = get_fatent_value(mydata, next_entry);
 540                 if (next_fat == 0) {
 541                         /* found free entry, link to entry */
 542                         set_fatent_value(mydata, entry, next_entry);
 543                         break;
 544                 }
 545                 next_entry++;
 546         }
 547         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 548                mydata->fatsize, entry, next_entry);
 549
 550         return next_entry;
 551 }
 552
 553 /*
 554  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 555  * Return 0 on success, -1 otherwise.
 556  */
 557 static int
 558 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 559              unsigned long size)
 560 {
 561         __u32 idx = 0;
 562         __u32 startsect;
 563         int ret;
 564
 565         if (clustnum > 0)
 566                 startsect = mydata->data_begin +
 567                                 clustnum * mydata->clust_size;
 568         else
 569                 startsect = mydata->rootdir_sect;
 570
 571         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 572
 573         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 574                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 575
 576                 printf("FAT: Misaligned buffer address (%p)\n", buffer);
 577
 578                 while (size >= mydata->sect_size) {
 579                         memcpy(tmpbuf, buffer, mydata->sect_size);
 580                         ret = disk_write(startsect++, 1, tmpbuf);
 581                         if (ret != 1) {
 582                                 debug("Error writing data (got %d)\n", ret);
 583                                 return -1;
 584                         }
 585
 586                         buffer += mydata->sect_size;
 587                         size -= mydata->sect_size;
 588                 }
 589         } else if (size >= mydata->sect_size) {
 590                 idx = size / mydata->sect_size;
 591                 ret = disk_write(startsect, idx, buffer);
 592                 if (ret != idx) {
 593                         debug("Error writing data (got %d)\n", ret);
 594                         return -1;
 595                 }
 596
 597                 startsect += idx;
 598                 idx *= mydata->sect_size;
 599                 buffer += idx;
 600                 size -= idx;
 601         }
 602
 603         if (size) {
 604                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 605
 606                 memcpy(tmpbuf, buffer, size);
 607                 ret = disk_write(startsect, 1, tmpbuf);
 608                 if (ret != 1) {
 609                         debug("Error writing data (got %d)\n", ret);
 610                         return -1;
 611                 }
 612         }
 613
 614         return 0;
 615 }
 616
 617 /*
 618  * Find the first empty cluster
 619  */
 620 static int find_empty_cluster(fsdata *mydata)
 621 {
 622         __u32 fat_val, entry = 3;
 623
 624         while (1) {
 625                 fat_val = get_fatent_value(mydata, entry);
 626                 if (fat_val == 0)
 627                         break;
 628                 entry++;
 629         }
 630
 631         return entry;
 632 }
 633
 634 /*
 635  * Write directory entries in 'get_dentfromdir_block' to block device
 636  */
 637 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 638 {
 639         int dir_newclust = 0;
 640
 641         if (set_cluster(mydata, dir_curclust,
 642                     get_dentfromdir_block,
 643                     mydata->clust_size * mydata->sect_size) != 0) {
 644                 printf("error: wrinting directory entry\n");
 645                 return;
 646         }
 647         dir_newclust = find_empty_cluster(mydata);
 648         set_fatent_value(mydata, dir_curclust, dir_newclust);
 649         if (mydata->fatsize == 32)
 650                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 651         else if (mydata->fatsize == 16)
 652                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 653
 654         dir_curclust = dir_newclust;
 655
 656         if (flush_dirty_fat_buffer(mydata) < 0)
 657                 return;
 658
 659         memset(get_dentfromdir_block, 0x00,
 660                 mydata->clust_size * mydata->sect_size);
 661
 662         *dentptr = (dir_entry *) get_dentfromdir_block;
 663 }
 664
 665 /*
 666  * Set empty cluster from 'entry' to the end of a file
 667  */
 668 static int clear_fatent(fsdata *mydata, __u32 entry)
 669 {
 670         __u32 fat_val;
 671
 672         while (1) {
 673                 fat_val = get_fatent_value(mydata, entry);
 674                 if (fat_val != 0)
 675                         set_fatent_value(mydata, entry, 0);
 676                 else
 677                         break;
 678
 679                 if (fat_val == 0xfffffff || fat_val == 0xffff)
 680                         break;
 681
 682                 entry = fat_val;
 683         }
 684
 685         /* Flush fat buffer */
 686         if (flush_dirty_fat_buffer(mydata) < 0)
 687                 return -1;
 688
 689         return 0;
 690 }
 691
 692 /*
 693  * Write at most 'maxsize' bytes from 'buffer' into
 694  * the file associated with 'dentptr'
 695  * Update the number of bytes written in *gotsize and return 0
 696  * or return -1 on fatal errors.
 697  */
 698 static int
 699 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 700               loff_t maxsize, loff_t *gotsize)
 701 {
 702         loff_t filesize = FAT2CPU32(dentptr->size);
 703         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 704         __u32 curclust = START(dentptr);
 705         __u32 endclust = 0, newclust = 0;
 706         loff_t actsize;
 707
 708         *gotsize = 0;
 709         debug("Filesize: %llu bytes\n", filesize);
 710
 711         if (maxsize > 0 && filesize > maxsize)
 712                 filesize = maxsize;
 713
 714         debug("%llu bytes\n", filesize);
 715
 716         if (!curclust) {
 717                 if (filesize) {
 718                         debug("error: nonempty clusterless file!\n");
 719                         return -1;
 720                 }
 721                 return 0;
 722         }
 723
 724         actsize = bytesperclust;
 725         endclust = curclust;
 726         do {
 727                 /* search for consecutive clusters */
 728                 while (actsize < filesize) {
 729                         newclust = determine_fatent(mydata, endclust);
 730
 731                         if ((newclust - 1) != endclust)
 732                                 goto getit;
 733
 734                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 735                                 debug("newclust: 0x%x\n", newclust);
 736                                 debug("Invalid FAT entry\n");
 737                                 return 0;
 738                         }
 739                         endclust = newclust;
 740                         actsize += bytesperclust;
 741                 }
 742
 743                 /* set remaining bytes */
 744                 actsize = filesize;
 745                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 746                         debug("error: writing cluster\n");
 747                         return -1;
 748                 }
 749                 *gotsize += actsize;
 750
 751                 /* Mark end of file in FAT */
 752                 if (mydata->fatsize == 16)
 753                         newclust = 0xffff;
 754                 else if (mydata->fatsize == 32)
 755                         newclust = 0xfffffff;
 756                 set_fatent_value(mydata, endclust, newclust);
 757
 758                 return 0;
 759 getit:
 760                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 761                         debug("error: writing cluster\n");
 762                         return -1;
 763                 }
 764                 *gotsize += actsize;
 765                 filesize -= actsize;
 766                 buffer += actsize;
 767
 768                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 769                         debug("newclust: 0x%x\n", newclust);
 770                         debug("Invalid FAT entry\n");
 771                         return 0;
 772                 }
 773                 actsize = bytesperclust;
 774                 curclust = endclust = newclust;
 775         } while (1);
 776 }
 777
 778 /*
 779  * Set start cluster in directory entry
 780  */
 781 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 782                                 __u32 start_cluster)
 783 {
 784         if (mydata->fatsize == 32)
 785                 dentptr->starthi =
 786                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 787         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 788 }
 789
 790 /*
 791  * Fill dir_entry
 792  */
 793 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 794         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 795 {
 796         set_start_cluster(mydata, dentptr, start_cluster);
 797         dentptr->size = cpu_to_le32(size);
 798
 799         dentptr->attr = attr;
 800
 801         set_name(dentptr, filename);
 802 }
 803
 804 /*
 805  * Check whether adding a file makes the file system to
 806  * exceed the size of the block device
 807  * Return -1 when overflow occurs, otherwise return 0
 808  */
 809 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 810 {
 811         __u32 startsect, sect_num, offset;
 812
 813         if (clustnum > 0) {
 814                 startsect = mydata->data_begin +
 815                                 clustnum * mydata->clust_size;
 816         } else {
 817                 startsect = mydata->rootdir_sect;
 818         }
 819
 820         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 821
 822         if (offset != 0)
 823                 sect_num++;
 824
 825         if (startsect + sect_num > cur_part_info.start + total_sector)
 826                 return -1;
 827         return 0;
 828 }
 829
 830 /*
 831  * Check if adding several entries exceed one cluster boundary
 832  */
 833 static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
 834 {
 835         int cur_position;
 836
 837         cur_position = (__u8 *)dentptr - get_dentfromdir_block;
 838
 839         if (cur_position >= mydata->clust_size * mydata->sect_size)
 840                 return 1;
 841         else
 842                 return 0;
 843 }
 844
 845 static dir_entry *empty_dentptr;
 846 /*
 847  * Find a directory entry based on filename or start cluster number
 848  * If the directory entry is not found,
 849  * the new position for writing a directory entry will be returned
 850  */
 851 static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
 852         char *filename, dir_entry *retdent, __u32 start)
 853 {
 854         __u32 curclust = (startsect - mydata->data_begin) / mydata->clust_size;
 855
 856         debug("get_dentfromdir: %s\n", filename);
 857
 858         while (1) {
 859                 dir_entry *dentptr;
 860
 861                 int i;
 862
 863                 if (get_cluster(mydata, curclust, get_dentfromdir_block,
 864                             mydata->clust_size * mydata->sect_size) != 0) {
 865                         printf("Error: reading directory block\n");
 866                         return NULL;
 867                 }
 868
 869                 dentptr = (dir_entry *)get_dentfromdir_block;
 870
 871                 dir_curclust = curclust;
 872
 873                 for (i = 0; i < DIRENTSPERCLUST; i++) {
 874                         char s_name[14], l_name[VFAT_MAXLEN_BYTES];
 875
 876                         l_name[0] = '\0';
 877                         if (dentptr->name[0] == DELETED_FLAG) {
 878                                 dentptr++;
 879                                 if (is_next_clust(mydata, dentptr))
 880                                         break;
 881                                 continue;
 882                         }
 883                         if ((dentptr->attr & ATTR_VOLUME)) {
 884                                 if (vfat_enabled &&
 885                                     (dentptr->attr & ATTR_VFAT) &&
 886                                     (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
 887                                         get_long_file_name(mydata, curclust,
 888                                                      get_dentfromdir_block,
 889                                                      &dentptr, l_name);
 890                                         debug("vfatname: |%s|\n", l_name);
 891                                 } else {
 892                                         /* Volume label or VFAT entry */
 893                                         dentptr++;
 894                                         if (is_next_clust(mydata, dentptr))
 895                                                 break;
 896                                         continue;
 897                                 }
 898                         }
 899                         if (dentptr->name[0] == 0) {
 900                                 debug("Dentname == NULL - %d\n", i);
 901                                 empty_dentptr = dentptr;
 902                                 return NULL;
 903                         }
 904
 905                         get_name(dentptr, s_name);
 906
 907                         if (strcmp(filename, s_name)
 908                             && strcmp(filename, l_name)) {
 909                                 debug("Mismatch: |%s|%s|\n",
 910                                         s_name, l_name);
 911                                 dentptr++;
 912                                 if (is_next_clust(mydata, dentptr))
 913                                         break;
 914                                 continue;
 915                         }
 916
 917                         memcpy(retdent, dentptr, sizeof(dir_entry));
 918
 919                         debug("DentName: %s", s_name);
 920                         debug(", start: 0x%x", START(dentptr));
 921                         debug(", size:  0x%x %s\n",
 922                               FAT2CPU32(dentptr->size),
 923                               (dentptr->attr & ATTR_DIR) ?
 924                               "(DIR)" : "");
 925
 926                         return dentptr;
 927                 }
 928
 929                 /*
 930                  * In FAT16/12, the root dir is locate before data area, shows
 931                  * in following:
 932                  * -------------------------------------------------------------
 933                  * | Boot | FAT1 & 2 | Root dir | Data (start from cluster #2) |
 934                  * -------------------------------------------------------------
 935                  *
 936                  * As a result if curclust is in Root dir, it is a negative
 937                  * number or 0, 1.
 938                  *
 939                  */
 940                 if (mydata->fatsize != 32 && (int)curclust <= 1) {
 941                         /* Current clust is in root dir, set to next clust */
 942                         curclust++;
 943                         if ((int)curclust <= 1)
 944                                 continue;       /* continue to find */
 945
 946                         /* Reach the end of root dir */
 947                         empty_dentptr = dentptr;
 948                         return NULL;
 949                 }
 950
 951                 curclust = get_fatent_value(mydata, dir_curclust);
 952                 if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 953                         empty_dentptr = dentptr;
 954                         return NULL;
 955                 }
 956                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 957                         debug("curclust: 0x%x\n", curclust);
 958                         debug("Invalid FAT entry\n");
 959                         return NULL;
 960                 }
 961         }
 962
 963         return NULL;
 964 }
 965
 966 static int do_fat_write(const char *filename, void *buffer, loff_t size,
 967                         loff_t *actwrite)
 968 {
 969         dir_entry *dentptr, *retdent;
 970         __u32 startsect;
 971         __u32 start_cluster;
 972         boot_sector bs;
 973         volume_info volinfo;
 974         fsdata datablock;
 975         fsdata *mydata = &datablock;
 976         int cursect;
 977         int ret = -1, name_len;
 978         char l_filename[VFAT_MAXLEN_BYTES];
 979
 980         *actwrite = size;
 981         dir_curclust = 0;
 982
 983         if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
 984                 debug("error: reading boot sector\n");
 985                 return -1;
 986         }
 987
 988         total_sector = bs.total_sect;
 989         if (total_sector == 0)
 990                 total_sector = (int)cur_part_info.size; /* cast of lbaint_t */
 991
 992         if (mydata->fatsize == 32)
 993                 mydata->fatlength = bs.fat32_length;
 994         else
 995                 mydata->fatlength = bs.fat_length;
 996
 997         mydata->fat_sect = bs.reserved;
 998
 999         cursect = mydata->rootdir_sect
1000                 = mydata->fat_sect + mydata->fatlength * bs.fats;
1001         num_of_fats = bs.fats;
1002
1003         mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
1004         mydata->clust_size = bs.cluster_size;
1005
1006         if (mydata->fatsize == 32) {
1007                 mydata->data_begin = mydata->rootdir_sect -
1008                                         (mydata->clust_size * 2);
1009         } else {
1010                 int rootdir_size;
1011
1012                 rootdir_size = ((bs.dir_entries[1]  * (int)256 +
1013                                  bs.dir_entries[0]) *
1014                                  sizeof(dir_entry)) /
1015                                  mydata->sect_size;
1016                 mydata->data_begin = mydata->rootdir_sect +
1017                                         rootdir_size -
1018                                         (mydata->clust_size * 2);
1019         }
1020
1021         mydata->fatbufnum = -1;
1022         mydata->fat_dirty = 0;
1023         mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
1024         if (mydata->fatbuf == NULL) {
1025                 debug("Error: allocating memory\n");
1026                 return -1;
1027         }
1028
1029         if (disk_read(cursect,
1030                 (mydata->fatsize == 32) ?
1031                 (mydata->clust_size) :
1032                 PREFETCH_BLOCKS, do_fat_read_at_block) < 0) {
1033                 debug("Error: reading rootdir block\n");
1034                 goto exit;
1035         }
1036         dentptr = (dir_entry *) do_fat_read_at_block;
1037
1038         name_len = strlen(filename);
1039         if (name_len >= VFAT_MAXLEN_BYTES)
1040                 name_len = VFAT_MAXLEN_BYTES - 1;
1041
1042         memcpy(l_filename, filename, name_len);
1043         l_filename[name_len] = 0; /* terminate the string */
1044         downcase(l_filename);
1045
1046         startsect = mydata->rootdir_sect;
1047         retdent = find_directory_entry(mydata, startsect,
1048                                 l_filename, dentptr, 0);
1049         if (retdent) {
1050                 /* Update file size and start_cluster in a directory entry */
1051                 retdent->size = cpu_to_le32(size);
1052                 start_cluster = START(retdent);
1053
1054                 if (start_cluster) {
1055                         if (size) {
1056                                 ret = check_overflow(mydata, start_cluster,
1057                                                         size);
1058                                 if (ret) {
1059                                         printf("Error: %llu overflow\n", size);
1060                                         goto exit;
1061                                 }
1062                         }
1063
1064                         ret = clear_fatent(mydata, start_cluster);
1065                         if (ret) {
1066                                 printf("Error: clearing FAT entries\n");
1067                                 goto exit;
1068                         }
1069
1070                         if (!size)
1071                                 set_start_cluster(mydata, retdent, 0);
1072                 } else if (size) {
1073                         ret = start_cluster = find_empty_cluster(mydata);
1074                         if (ret < 0) {
1075                                 printf("Error: finding empty cluster\n");
1076                                 goto exit;
1077                         }
1078
1079                         ret = check_overflow(mydata, start_cluster, size);
1080                         if (ret) {
1081                                 printf("Error: %llu overflow\n", size);
1082                                 goto exit;
1083                         }
1084
1085                         set_start_cluster(mydata, retdent, start_cluster);
1086                 }
1087         } else {
1088                 /* Set short name to set alias checksum field in dir_slot */
1089                 set_name(empty_dentptr, filename);
1090                 fill_dir_slot(mydata, &empty_dentptr, filename);
1091
1092                 if (size) {
1093                         ret = start_cluster = find_empty_cluster(mydata);
1094                         if (ret < 0) {
1095                                 printf("Error: finding empty cluster\n");
1096                                 goto exit;
1097                         }
1098
1099                         ret = check_overflow(mydata, start_cluster, size);
1100                         if (ret) {
1101                                 printf("Error: %llu overflow\n", size);
1102                                 goto exit;
1103                         }
1104                 } else {
1105                         start_cluster = 0;
1106                 }
1107
1108                 /* Set attribute as archieve for regular file */
1109                 fill_dentry(mydata, empty_dentptr, filename,
1110                         start_cluster, size, 0x20);
1111
1112                 retdent = empty_dentptr;
1113         }
1114
1115         ret = set_contents(mydata, retdent, buffer, size, actwrite);
1116         if (ret < 0) {
1117                 printf("Error: writing contents\n");
1118                 goto exit;
1119         }
1120         debug("attempt to write 0x%llx bytes\n", *actwrite);
1121
1122         /* Flush fat buffer */
1123         ret = flush_dirty_fat_buffer(mydata);
1124         if (ret) {
1125                 printf("Error: flush fat buffer\n");
1126                 goto exit;
1127         }
1128
1129         /* Write directory table to device */
1130         ret = set_cluster(mydata, dir_curclust, get_dentfromdir_block,
1131                         mydata->clust_size * mydata->sect_size);
1132         if (ret)
1133                 printf("Error: writing directory entry\n");
1134
1135 exit:
1136         free(mydata->fatbuf);
1137         return ret;
1138 }
1139
1140 int file_fat_write(const char *filename, void *buffer, loff_t offset,
1141                    loff_t maxsize, loff_t *actwrite)
1142 {
1143         if (offset != 0) {
1144                 printf("Error: non zero offset is currently not supported.\n");
1145                 return -1;
1146         }
1147
1148         printf("writing %s\n", filename);
1149         return do_fat_write(filename, buffer, maxsize, actwrite);
1150 }