git.sur5r.net Git - u-boot/blob - 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_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         startblock += mydata->fat_sect;
 115
 116         if (getsize > fatlength)
 117                 getsize = fatlength;
 118
 119         /* Write FAT buf */
 120         if (disk_write(startblock, getsize, bufptr) < 0) {
 121                 debug("error: writing FAT blocks\n");
 122                 return -1;
 123         }
 124
 125         if (num_of_fats == 2) {
 126                 /* Update corresponding second FAT blocks */
 127                 startblock += mydata->fatlength;
 128                 if (disk_write(startblock, getsize, bufptr) < 0) {
 129                         debug("error: writing second FAT blocks\n");
 130                         return -1;
 131                 }
 132         }
 133
 134         return 0;
 135 }
 136
 137 /*
 138  * Get the entry at index 'entry' in a FAT (12/16/32) table.
 139  * On failure 0x00 is returned.
 140  * When bufnum is changed, write back the previous fatbuf to the disk.
 141  */
 142 static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
 143 {
 144         __u32 bufnum;
 145         __u32 off16, offset;
 146         __u32 ret = 0x00;
 147         __u16 val1, val2;
 148
 149         if (CHECK_CLUST(entry, mydata->fatsize)) {
 150                 printf("Error: Invalid FAT entry: 0x%08x\n", entry);
 151                 return ret;
 152         }
 153
 154         switch (mydata->fatsize) {
 155         case 32:
 156                 bufnum = entry / FAT32BUFSIZE;
 157                 offset = entry - bufnum * FAT32BUFSIZE;
 158                 break;
 159         case 16:
 160                 bufnum = entry / FAT16BUFSIZE;
 161                 offset = entry - bufnum * FAT16BUFSIZE;
 162                 break;
 163         case 12:
 164                 bufnum = entry / FAT12BUFSIZE;
 165                 offset = entry - bufnum * FAT12BUFSIZE;
 166                 break;
 167
 168         default:
 169                 /* Unsupported FAT size */
 170                 return ret;
 171         }
 172
 173         debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
 174                mydata->fatsize, entry, entry, offset, offset);
 175
 176         /* Read a new block of FAT entries into the cache. */
 177         if (bufnum != mydata->fatbufnum) {
 178                 int getsize = FATBUFBLOCKS;
 179                 __u8 *bufptr = mydata->fatbuf;
 180                 __u32 fatlength = mydata->fatlength;
 181                 __u32 startblock = bufnum * FATBUFBLOCKS;
 182
 183                 if (getsize > fatlength)
 184                         getsize = fatlength;
 185
 186                 startblock += mydata->fat_sect; /* Offset from start of disk */
 187
 188                 /* Write back the fatbuf to the disk */
 189                 if (mydata->fatbufnum != -1) {
 190                         if (flush_fat_buffer(mydata) < 0)
 191                                 return -1;
 192                 }
 193
 194                 if (disk_read(startblock, getsize, bufptr) < 0) {
 195                         debug("Error reading FAT blocks\n");
 196                         return ret;
 197                 }
 198                 mydata->fatbufnum = bufnum;
 199         }
 200
 201         /* Get the actual entry from the table */
 202         switch (mydata->fatsize) {
 203         case 32:
 204                 ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
 205                 break;
 206         case 16:
 207                 ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
 208                 break;
 209         case 12:
 210                 off16 = (offset * 3) / 4;
 211
 212                 switch (offset & 0x3) {
 213                 case 0:
 214                         ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
 215                         ret &= 0xfff;
 216                         break;
 217                 case 1:
 218                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 219                         val1 &= 0xf000;
 220                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 221                         val2 &= 0x00ff;
 222                         ret = (val2 << 4) | (val1 >> 12);
 223                         break;
 224                 case 2:
 225                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 226                         val1 &= 0xff00;
 227                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 228                         val2 &= 0x000f;
 229                         ret = (val2 << 8) | (val1 >> 8);
 230                         break;
 231                 case 3:
 232                         ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 233                         ret = (ret & 0xfff0) >> 4;
 234                         break;
 235                 default:
 236                         break;
 237                 }
 238                 break;
 239         }
 240         debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
 241                mydata->fatsize, ret, entry, offset);
 242
 243         return ret;
 244 }
 245
 246 /*
 247  * Set the file name information from 'name' into 'slotptr',
 248  */
 249 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 250 {
 251         int j, end_idx = 0;
 252
 253         for (j = 0; j <= 8; j += 2) {
 254                 if (name[*idx] == 0x00) {
 255                         slotptr->name0_4[j] = 0;
 256                         slotptr->name0_4[j + 1] = 0;
 257                         end_idx++;
 258                         goto name0_4;
 259                 }
 260                 slotptr->name0_4[j] = name[*idx];
 261                 (*idx)++;
 262                 end_idx++;
 263         }
 264         for (j = 0; j <= 10; j += 2) {
 265                 if (name[*idx] == 0x00) {
 266                         slotptr->name5_10[j] = 0;
 267                         slotptr->name5_10[j + 1] = 0;
 268                         end_idx++;
 269                         goto name5_10;
 270                 }
 271                 slotptr->name5_10[j] = name[*idx];
 272                 (*idx)++;
 273                 end_idx++;
 274         }
 275         for (j = 0; j <= 2; j += 2) {
 276                 if (name[*idx] == 0x00) {
 277                         slotptr->name11_12[j] = 0;
 278                         slotptr->name11_12[j + 1] = 0;
 279                         end_idx++;
 280                         goto name11_12;
 281                 }
 282                 slotptr->name11_12[j] = name[*idx];
 283                 (*idx)++;
 284                 end_idx++;
 285         }
 286
 287         if (name[*idx] == 0x00)
 288                 return 1;
 289
 290         return 0;
 291 /* Not used characters are filled with 0xff 0xff */
 292 name0_4:
 293         for (; end_idx < 5; end_idx++) {
 294                 slotptr->name0_4[end_idx * 2] = 0xff;
 295                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 296         }
 297         end_idx = 5;
 298 name5_10:
 299         end_idx -= 5;
 300         for (; end_idx < 6; end_idx++) {
 301                 slotptr->name5_10[end_idx * 2] = 0xff;
 302                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 303         }
 304         end_idx = 11;
 305 name11_12:
 306         end_idx -= 11;
 307         for (; end_idx < 2; end_idx++) {
 308                 slotptr->name11_12[end_idx * 2] = 0xff;
 309                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 310         }
 311
 312         return 1;
 313 }
 314
 315 static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
 316 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);
 317
 318 /*
 319  * Fill dir_slot entries with appropriate name, id, and attr
 320  * The real directory entry is returned by 'dentptr'
 321  */
 322 static void
 323 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 324 {
 325         dir_slot *slotptr = (dir_slot *)get_contents_vfatname_block;
 326         __u8 counter = 0, checksum;
 327         int idx = 0, ret;
 328
 329         /* Get short file name checksum value */
 330         checksum = mkcksum((*dentptr)->name, (*dentptr)->ext);
 331
 332         do {
 333                 memset(slotptr, 0x00, sizeof(dir_slot));
 334                 ret = str2slot(slotptr, l_name, &idx);
 335                 slotptr->id = ++counter;
 336                 slotptr->attr = ATTR_VFAT;
 337                 slotptr->alias_checksum = checksum;
 338                 slotptr++;
 339         } while (ret == 0);
 340
 341         slotptr--;
 342         slotptr->id |= LAST_LONG_ENTRY_MASK;
 343
 344         while (counter >= 1) {
 345                 if (is_next_clust(mydata, *dentptr)) {
 346                         /* A new cluster is allocated for directory table */
 347                         flush_dir_table(mydata, dentptr);
 348                 }
 349                 memcpy(*dentptr, slotptr, sizeof(dir_slot));
 350                 (*dentptr)++;
 351                 slotptr--;
 352                 counter--;
 353         }
 354
 355         if (is_next_clust(mydata, *dentptr)) {
 356                 /* A new cluster is allocated for directory table */
 357                 flush_dir_table(mydata, dentptr);
 358         }
 359 }
 360
 361 static __u32 dir_curclust;
 362
 363 /*
 364  * Extract the full long filename starting at 'retdent' (which is really
 365  * a slot) into 'l_name'. If successful also copy the real directory entry
 366  * into 'retdent'
 367  * If additional adjacent cluster for directory entries is read into memory,
 368  * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and
 369  * the location of the real directory entry is returned by 'retdent'
 370  * Return 0 on success, -1 otherwise.
 371  */
 372 static int
 373 get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 374               dir_entry **retdent, char *l_name)
 375 {
 376         dir_entry *realdent;
 377         dir_slot *slotptr = (dir_slot *)(*retdent);
 378         dir_slot *slotptr2 = NULL;
 379         __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
 380                                                         PREFETCH_BLOCKS :
 381                                                         mydata->clust_size);
 382         __u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
 383         int idx = 0, cur_position = 0;
 384
 385         if (counter > VFAT_MAXSEQ) {
 386                 debug("Error: VFAT name is too long\n");
 387                 return -1;
 388         }
 389
 390         while ((__u8 *)slotptr < buflimit) {
 391                 if (counter == 0)
 392                         break;
 393                 if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
 394                         return -1;
 395                 slotptr++;
 396                 counter--;
 397         }
 398
 399         if ((__u8 *)slotptr >= buflimit) {
 400                 if (curclust == 0)
 401                         return -1;
 402                 curclust = get_fatent_value(mydata, dir_curclust);
 403                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 404                         debug("curclust: 0x%x\n", curclust);
 405                         printf("Invalid FAT entry\n");
 406                         return -1;
 407                 }
 408
 409                 dir_curclust = curclust;
 410
 411                 if (get_cluster(mydata, curclust, get_contents_vfatname_block,
 412                                 mydata->clust_size * mydata->sect_size) != 0) {
 413                         debug("Error: reading directory block\n");
 414                         return -1;
 415                 }
 416
 417                 slotptr2 = (dir_slot *)get_contents_vfatname_block;
 418                 while (counter > 0) {
 419                         if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
 420                             & 0xff) != counter)
 421                                 return -1;
 422                         slotptr2++;
 423                         counter--;
 424                 }
 425
 426                 /* Save the real directory entry */
 427                 realdent = (dir_entry *)slotptr2;
 428                 while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
 429                         slotptr2--;
 430                         slot2str(slotptr2, l_name, &idx);
 431                 }
 432         } else {
 433                 /* Save the real directory entry */
 434                 realdent = (dir_entry *)slotptr;
 435         }
 436
 437         do {
 438                 slotptr--;
 439                 if (slot2str(slotptr, l_name, &idx))
 440                         break;
 441         } while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
 442
 443         l_name[idx] = '\0';
 444         if (*l_name == DELETED_FLAG)
 445                 *l_name = '\0';
 446         else if (*l_name == aRING)
 447                 *l_name = DELETED_FLAG;
 448         downcase(l_name);
 449
 450         /* Return the real directory entry */
 451         *retdent = realdent;
 452
 453         if (slotptr2) {
 454                 memcpy(get_dentfromdir_block, get_contents_vfatname_block,
 455                         mydata->clust_size * mydata->sect_size);
 456                 cur_position = (__u8 *)realdent - get_contents_vfatname_block;
 457                 *retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
 458         }
 459
 460         return 0;
 461 }
 462
 463 /*
 464  * Set the entry at index 'entry' in a FAT (16/32) table.
 465  */
 466 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 467 {
 468         __u32 bufnum, offset;
 469
 470         switch (mydata->fatsize) {
 471         case 32:
 472                 bufnum = entry / FAT32BUFSIZE;
 473                 offset = entry - bufnum * FAT32BUFSIZE;
 474                 break;
 475         case 16:
 476                 bufnum = entry / FAT16BUFSIZE;
 477                 offset = entry - bufnum * FAT16BUFSIZE;
 478                 break;
 479         default:
 480                 /* Unsupported FAT size */
 481                 return -1;
 482         }
 483
 484         /* Read a new block of FAT entries into the cache. */
 485         if (bufnum != mydata->fatbufnum) {
 486                 int getsize = FATBUFBLOCKS;
 487                 __u8 *bufptr = mydata->fatbuf;
 488                 __u32 fatlength = mydata->fatlength;
 489                 __u32 startblock = bufnum * FATBUFBLOCKS;
 490
 491                 fatlength *= mydata->sect_size;
 492                 startblock += mydata->fat_sect;
 493
 494                 if (getsize > fatlength)
 495                         getsize = fatlength;
 496
 497                 if (mydata->fatbufnum != -1) {
 498                         if (flush_fat_buffer(mydata) < 0)
 499                                 return -1;
 500                 }
 501
 502                 if (disk_read(startblock, getsize, bufptr) < 0) {
 503                         debug("Error reading FAT blocks\n");
 504                         return -1;
 505                 }
 506                 mydata->fatbufnum = bufnum;
 507         }
 508
 509         /* Set the actual entry */
 510         switch (mydata->fatsize) {
 511         case 32:
 512                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 513                 break;
 514         case 16:
 515                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 516                 break;
 517         default:
 518                 return -1;
 519         }
 520
 521         return 0;
 522 }
 523
 524 /*
 525  * Determine the entry value at index 'entry' in a FAT (16/32) table
 526  */
 527 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 528 {
 529         __u32 next_fat, next_entry = entry + 1;
 530
 531         while (1) {
 532                 next_fat = get_fatent_value(mydata, next_entry);
 533                 if (next_fat == 0) {
 534                         set_fatent_value(mydata, entry, next_entry);
 535                         break;
 536                 }
 537                 next_entry++;
 538         }
 539         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 540                mydata->fatsize, entry, next_entry);
 541
 542         return next_entry;
 543 }
 544
 545 /*
 546  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 547  * Return 0 on success, -1 otherwise.
 548  */
 549 static int
 550 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 551              unsigned long size)
 552 {
 553         __u32 idx = 0;
 554         __u32 startsect;
 555         int ret;
 556
 557         if (clustnum > 0)
 558                 startsect = mydata->data_begin +
 559                                 clustnum * mydata->clust_size;
 560         else
 561                 startsect = mydata->rootdir_sect;
 562
 563         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 564
 565         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 566                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 567
 568                 printf("FAT: Misaligned buffer address (%p)\n", buffer);
 569
 570                 while (size >= mydata->sect_size) {
 571                         memcpy(tmpbuf, buffer, mydata->sect_size);
 572                         ret = disk_write(startsect++, 1, tmpbuf);
 573                         if (ret != 1) {
 574                                 debug("Error writing data (got %d)\n", ret);
 575                                 return -1;
 576                         }
 577
 578                         buffer += mydata->sect_size;
 579                         size -= mydata->sect_size;
 580                 }
 581         } else if (size >= mydata->sect_size) {
 582                 idx = size / mydata->sect_size;
 583                 ret = disk_write(startsect, idx, buffer);
 584                 if (ret != idx) {
 585                         debug("Error writing data (got %d)\n", ret);
 586                         return -1;
 587                 }
 588
 589                 startsect += idx;
 590                 idx *= mydata->sect_size;
 591                 buffer += idx;
 592                 size -= idx;
 593         }
 594
 595         if (size) {
 596                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 597
 598                 memcpy(tmpbuf, buffer, size);
 599                 ret = disk_write(startsect, 1, tmpbuf);
 600                 if (ret != 1) {
 601                         debug("Error writing data (got %d)\n", ret);
 602                         return -1;
 603                 }
 604         }
 605
 606         return 0;
 607 }
 608
 609 /*
 610  * Find the first empty cluster
 611  */
 612 static int find_empty_cluster(fsdata *mydata)
 613 {
 614         __u32 fat_val, entry = 3;
 615
 616         while (1) {
 617                 fat_val = get_fatent_value(mydata, entry);
 618                 if (fat_val == 0)
 619                         break;
 620                 entry++;
 621         }
 622
 623         return entry;
 624 }
 625
 626 /*
 627  * Write directory entries in 'get_dentfromdir_block' to block device
 628  */
 629 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 630 {
 631         int dir_newclust = 0;
 632
 633         if (set_cluster(mydata, dir_curclust,
 634                     get_dentfromdir_block,
 635                     mydata->clust_size * mydata->sect_size) != 0) {
 636                 printf("error: wrinting directory entry\n");
 637                 return;
 638         }
 639         dir_newclust = find_empty_cluster(mydata);
 640         set_fatent_value(mydata, dir_curclust, dir_newclust);
 641         if (mydata->fatsize == 32)
 642                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 643         else if (mydata->fatsize == 16)
 644                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 645
 646         dir_curclust = dir_newclust;
 647
 648         if (flush_fat_buffer(mydata) < 0)
 649                 return;
 650
 651         memset(get_dentfromdir_block, 0x00,
 652                 mydata->clust_size * mydata->sect_size);
 653
 654         *dentptr = (dir_entry *) get_dentfromdir_block;
 655 }
 656
 657 /*
 658  * Set empty cluster from 'entry' to the end of a file
 659  */
 660 static int clear_fatent(fsdata *mydata, __u32 entry)
 661 {
 662         __u32 fat_val;
 663
 664         while (1) {
 665                 fat_val = get_fatent_value(mydata, entry);
 666                 if (fat_val != 0)
 667                         set_fatent_value(mydata, entry, 0);
 668                 else
 669                         break;
 670
 671                 if (fat_val == 0xfffffff || fat_val == 0xffff)
 672                         break;
 673
 674                 entry = fat_val;
 675         }
 676
 677         /* Flush fat buffer */
 678         if (flush_fat_buffer(mydata) < 0)
 679                 return -1;
 680
 681         return 0;
 682 }
 683
 684 /*
 685  * Write at most 'maxsize' bytes from 'buffer' into
 686  * the file associated with 'dentptr'
 687  * Update the number of bytes written in *gotsize and return 0
 688  * or return -1 on fatal errors.
 689  */
 690 static int
 691 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 692               loff_t maxsize, loff_t *gotsize)
 693 {
 694         loff_t filesize = FAT2CPU32(dentptr->size);
 695         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 696         __u32 curclust = START(dentptr);
 697         __u32 endclust = 0, newclust = 0;
 698         loff_t actsize;
 699
 700         *gotsize = 0;
 701         debug("Filesize: %llu bytes\n", filesize);
 702
 703         if (maxsize > 0 && filesize > maxsize)
 704                 filesize = maxsize;
 705
 706         debug("%llu bytes\n", filesize);
 707
 708         if (!curclust) {
 709                 if (filesize) {
 710                         debug("error: nonempty clusterless file!\n");
 711                         return -1;
 712                 }
 713                 return 0;
 714         }
 715
 716         actsize = bytesperclust;
 717         endclust = curclust;
 718         do {
 719                 /* search for consecutive clusters */
 720                 while (actsize < filesize) {
 721                         newclust = determine_fatent(mydata, endclust);
 722
 723                         if ((newclust - 1) != endclust)
 724                                 goto getit;
 725
 726                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 727                                 debug("newclust: 0x%x\n", newclust);
 728                                 debug("Invalid FAT entry\n");
 729                                 return 0;
 730                         }
 731                         endclust = newclust;
 732                         actsize += bytesperclust;
 733                 }
 734
 735                 /* set remaining bytes */
 736                 actsize = filesize;
 737                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 738                         debug("error: writing cluster\n");
 739                         return -1;
 740                 }
 741                 *gotsize += actsize;
 742
 743                 /* Mark end of file in FAT */
 744                 if (mydata->fatsize == 16)
 745                         newclust = 0xffff;
 746                 else if (mydata->fatsize == 32)
 747                         newclust = 0xfffffff;
 748                 set_fatent_value(mydata, endclust, newclust);
 749
 750                 return 0;
 751 getit:
 752                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 753                         debug("error: writing cluster\n");
 754                         return -1;
 755                 }
 756                 *gotsize += actsize;
 757                 filesize -= actsize;
 758                 buffer += actsize;
 759
 760                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 761                         debug("newclust: 0x%x\n", newclust);
 762                         debug("Invalid FAT entry\n");
 763                         return 0;
 764                 }
 765                 actsize = bytesperclust;
 766                 curclust = endclust = newclust;
 767         } while (1);
 768 }
 769
 770 /*
 771  * Set start cluster in directory entry
 772  */
 773 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 774                                 __u32 start_cluster)
 775 {
 776         if (mydata->fatsize == 32)
 777                 dentptr->starthi =
 778                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 779         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 780 }
 781
 782 /*
 783  * Fill dir_entry
 784  */
 785 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 786         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 787 {
 788         set_start_cluster(mydata, dentptr, start_cluster);
 789         dentptr->size = cpu_to_le32(size);
 790
 791         dentptr->attr = attr;
 792
 793         set_name(dentptr, filename);
 794 }
 795
 796 /*
 797  * Check whether adding a file makes the file system to
 798  * exceed the size of the block device
 799  * Return -1 when overflow occurs, otherwise return 0
 800  */
 801 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 802 {
 803         __u32 startsect, sect_num, offset;
 804
 805         if (clustnum > 0) {
 806                 startsect = mydata->data_begin +
 807                                 clustnum * mydata->clust_size;
 808         } else {
 809                 startsect = mydata->rootdir_sect;
 810         }
 811
 812         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 813
 814         if (offset != 0)
 815                 sect_num++;
 816
 817         if (startsect + sect_num > cur_part_info.start + total_sector)
 818                 return -1;
 819         return 0;
 820 }
 821
 822 /*
 823  * Check if adding several entries exceed one cluster boundary
 824  */
 825 static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
 826 {
 827         int cur_position;
 828
 829         cur_position = (__u8 *)dentptr - get_dentfromdir_block;
 830
 831         if (cur_position >= mydata->clust_size * mydata->sect_size)
 832                 return 1;
 833         else
 834                 return 0;
 835 }
 836
 837 static dir_entry *empty_dentptr;
 838 /*
 839  * Find a directory entry based on filename or start cluster number
 840  * If the directory entry is not found,
 841  * the new position for writing a directory entry will be returned
 842  */
 843 static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
 844         char *filename, dir_entry *retdent, __u32 start)
 845 {
 846         __u32 curclust = (startsect - mydata->data_begin) / mydata->clust_size;
 847
 848         debug("get_dentfromdir: %s\n", filename);
 849
 850         while (1) {
 851                 dir_entry *dentptr;
 852
 853                 int i;
 854
 855                 if (get_cluster(mydata, curclust, get_dentfromdir_block,
 856                             mydata->clust_size * mydata->sect_size) != 0) {
 857                         printf("Error: reading directory block\n");
 858                         return NULL;
 859                 }
 860
 861                 dentptr = (dir_entry *)get_dentfromdir_block;
 862
 863                 dir_curclust = curclust;
 864
 865                 for (i = 0; i < DIRENTSPERCLUST; i++) {
 866                         char s_name[14], l_name[VFAT_MAXLEN_BYTES];
 867
 868                         l_name[0] = '\0';
 869                         if (dentptr->name[0] == DELETED_FLAG) {
 870                                 dentptr++;
 871                                 if (is_next_clust(mydata, dentptr))
 872                                         break;
 873                                 continue;
 874                         }
 875                         if ((dentptr->attr & ATTR_VOLUME)) {
 876                                 if (vfat_enabled &&
 877                                     (dentptr->attr & ATTR_VFAT) &&
 878                                     (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
 879                                         get_long_file_name(mydata, curclust,
 880                                                      get_dentfromdir_block,
 881                                                      &dentptr, l_name);
 882                                         debug("vfatname: |%s|\n", l_name);
 883                                 } else {
 884                                         /* Volume label or VFAT entry */
 885                                         dentptr++;
 886                                         if (is_next_clust(mydata, dentptr))
 887                                                 break;
 888                                         continue;
 889                                 }
 890                         }
 891                         if (dentptr->name[0] == 0) {
 892                                 debug("Dentname == NULL - %d\n", i);
 893                                 empty_dentptr = dentptr;
 894                                 return NULL;
 895                         }
 896
 897                         get_name(dentptr, s_name);
 898
 899                         if (strcmp(filename, s_name)
 900                             && strcmp(filename, l_name)) {
 901                                 debug("Mismatch: |%s|%s|\n",
 902                                         s_name, l_name);
 903                                 dentptr++;
 904                                 if (is_next_clust(mydata, dentptr))
 905                                         break;
 906                                 continue;
 907                         }
 908
 909                         memcpy(retdent, dentptr, sizeof(dir_entry));
 910
 911                         debug("DentName: %s", s_name);
 912                         debug(", start: 0x%x", START(dentptr));
 913                         debug(", size:  0x%x %s\n",
 914                               FAT2CPU32(dentptr->size),
 915                               (dentptr->attr & ATTR_DIR) ?
 916                               "(DIR)" : "");
 917
 918                         return dentptr;
 919                 }
 920
 921                 /*
 922                  * In FAT16/12, the root dir is locate before data area, shows
 923                  * in following:
 924                  * -------------------------------------------------------------
 925                  * | Boot | FAT1 & 2 | Root dir | Data (start from cluster #2) |
 926                  * -------------------------------------------------------------
 927                  *
 928                  * As a result if curclust is in Root dir, it is a negative
 929                  * number or 0, 1.
 930                  *
 931                  */
 932                 if (mydata->fatsize != 32 && (int)curclust <= 1) {
 933                         /* Current clust is in root dir, set to next clust */
 934                         curclust++;
 935                         if ((int)curclust <= 1)
 936                                 continue;       /* continue to find */
 937
 938                         /* Reach the end of root dir */
 939                         empty_dentptr = dentptr;
 940                         return NULL;
 941                 }
 942
 943                 curclust = get_fatent_value(mydata, dir_curclust);
 944                 if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 945                         empty_dentptr = dentptr;
 946                         return NULL;
 947                 }
 948                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 949                         debug("curclust: 0x%x\n", curclust);
 950                         debug("Invalid FAT entry\n");
 951                         return NULL;
 952                 }
 953         }
 954
 955         return NULL;
 956 }
 957
 958 static int do_fat_write(const char *filename, void *buffer, loff_t size,
 959                         loff_t *actwrite)
 960 {
 961         dir_entry *dentptr, *retdent;
 962         __u32 startsect;
 963         __u32 start_cluster;
 964         boot_sector bs;
 965         volume_info volinfo;
 966         fsdata datablock;
 967         fsdata *mydata = &datablock;
 968         int cursect;
 969         int ret = -1, name_len;
 970         char l_filename[VFAT_MAXLEN_BYTES];
 971
 972         *actwrite = size;
 973         dir_curclust = 0;
 974
 975         if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
 976                 debug("error: reading boot sector\n");
 977                 return -1;
 978         }
 979
 980         total_sector = bs.total_sect;
 981         if (total_sector == 0)
 982                 total_sector = (int)cur_part_info.size; /* cast of lbaint_t */
 983
 984         if (mydata->fatsize == 32)
 985                 mydata->fatlength = bs.fat32_length;
 986         else
 987                 mydata->fatlength = bs.fat_length;
 988
 989         mydata->fat_sect = bs.reserved;
 990
 991         cursect = mydata->rootdir_sect
 992                 = mydata->fat_sect + mydata->fatlength * bs.fats;
 993         num_of_fats = bs.fats;
 994
 995         mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
 996         mydata->clust_size = bs.cluster_size;
 997
 998         if (mydata->fatsize == 32) {
 999                 mydata->data_begin = mydata->rootdir_sect -
1000                                         (mydata->clust_size * 2);
1001         } else {
1002                 int rootdir_size;
1003
1004                 rootdir_size = ((bs.dir_entries[1]  * (int)256 +
1005                                  bs.dir_entries[0]) *
1006                                  sizeof(dir_entry)) /
1007                                  mydata->sect_size;
1008                 mydata->data_begin = mydata->rootdir_sect +
1009                                         rootdir_size -
1010                                         (mydata->clust_size * 2);
1011         }
1012
1013         mydata->fatbufnum = -1;
1014         mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
1015         if (mydata->fatbuf == NULL) {
1016                 debug("Error: allocating memory\n");
1017                 return -1;
1018         }
1019
1020         if (disk_read(cursect,
1021                 (mydata->fatsize == 32) ?
1022                 (mydata->clust_size) :
1023                 PREFETCH_BLOCKS, do_fat_read_at_block) < 0) {
1024                 debug("Error: reading rootdir block\n");
1025                 goto exit;
1026         }
1027         dentptr = (dir_entry *) do_fat_read_at_block;
1028
1029         name_len = strlen(filename);
1030         if (name_len >= VFAT_MAXLEN_BYTES)
1031                 name_len = VFAT_MAXLEN_BYTES - 1;
1032
1033         memcpy(l_filename, filename, name_len);
1034         l_filename[name_len] = 0; /* terminate the string */
1035         downcase(l_filename);
1036
1037         startsect = mydata->rootdir_sect;
1038         retdent = find_directory_entry(mydata, startsect,
1039                                 l_filename, dentptr, 0);
1040         if (retdent) {
1041                 /* Update file size and start_cluster in a directory entry */
1042                 retdent->size = cpu_to_le32(size);
1043                 start_cluster = START(retdent);
1044
1045                 if (start_cluster) {
1046                         if (size) {
1047                                 ret = check_overflow(mydata, start_cluster,
1048                                                         size);
1049                                 if (ret) {
1050                                         printf("Error: %llu overflow\n", size);
1051                                         goto exit;
1052                                 }
1053                         }
1054
1055                         ret = clear_fatent(mydata, start_cluster);
1056                         if (ret) {
1057                                 printf("Error: clearing FAT entries\n");
1058                                 goto exit;
1059                         }
1060
1061                         if (!size)
1062                                 set_start_cluster(mydata, retdent, 0);
1063                 } else if (size) {
1064                         ret = start_cluster = find_empty_cluster(mydata);
1065                         if (ret < 0) {
1066                                 printf("Error: finding empty cluster\n");
1067                                 goto exit;
1068                         }
1069
1070                         ret = check_overflow(mydata, start_cluster, size);
1071                         if (ret) {
1072                                 printf("Error: %llu overflow\n", size);
1073                                 goto exit;
1074                         }
1075
1076                         set_start_cluster(mydata, retdent, start_cluster);
1077                 }
1078         } else {
1079                 /* Set short name to set alias checksum field in dir_slot */
1080                 set_name(empty_dentptr, filename);
1081                 fill_dir_slot(mydata, &empty_dentptr, filename);
1082
1083                 if (size) {
1084                         ret = start_cluster = find_empty_cluster(mydata);
1085                         if (ret < 0) {
1086                                 printf("Error: finding empty cluster\n");
1087                                 goto exit;
1088                         }
1089
1090                         ret = check_overflow(mydata, start_cluster, size);
1091                         if (ret) {
1092                                 printf("Error: %llu overflow\n", size);
1093                                 goto exit;
1094                         }
1095                 } else {
1096                         start_cluster = 0;
1097                 }
1098
1099                 /* Set attribute as archieve for regular file */
1100                 fill_dentry(mydata, empty_dentptr, filename,
1101                         start_cluster, size, 0x20);
1102
1103                 retdent = empty_dentptr;
1104         }
1105
1106         ret = set_contents(mydata, retdent, buffer, size, actwrite);
1107         if (ret < 0) {
1108                 printf("Error: writing contents\n");
1109                 goto exit;
1110         }
1111         debug("attempt to write 0x%llx bytes\n", *actwrite);
1112
1113         /* Flush fat buffer */
1114         ret = flush_fat_buffer(mydata);
1115         if (ret) {
1116                 printf("Error: flush fat buffer\n");
1117                 goto exit;
1118         }
1119
1120         /* Write directory table to device */
1121         ret = set_cluster(mydata, dir_curclust, get_dentfromdir_block,
1122                         mydata->clust_size * mydata->sect_size);
1123         if (ret)
1124                 printf("Error: writing directory entry\n");
1125
1126 exit:
1127         free(mydata->fatbuf);
1128         return ret;
1129 }
1130
1131 int file_fat_write(const char *filename, void *buffer, loff_t offset,
1132                    loff_t maxsize, loff_t *actwrite)
1133 {
1134         if (offset != 0) {
1135                 printf("Error: non zero offset is currently not supported.\n");
1136                 return -1;
1137         }
1138
1139         printf("writing %s\n", filename);
1140         return do_fat_write(filename, buffer, maxsize, actwrite);
1141 }