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