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