fs/fat/fat_write.c

   1 /*
   2  * fat_write.c
   3  *
   4  * R/W (V)FAT 12/16/32 filesystem implementation by Donggeun Kim
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #include <common.h>
  10 #include <command.h>
  11 #include <config.h>
  12 #include <fat.h>
  13 #include <asm/byteorder.h>
  14 #include <part.h>
  15 #include <linux/ctype.h>
  16 #include <div64.h>
  17 #include <linux/math64.h>
  18 #include "fat.c"
  19
  20 static void uppercase(char *str, int len)
  21 {
  22         int i;
  23
  24         for (i = 0; i < len; i++) {
  25                 *str = toupper(*str);
  26                 str++;
  27         }
  28 }
  29
  30 static int total_sector;
  31 static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
  32 {
  33         ulong ret;
  34
  35         if (!cur_dev)
  36                 return -1;
  37
  38         if (cur_part_info.start + block + nr_blocks >
  39                 cur_part_info.start + total_sector) {
  40                 printf("error: overflow occurs\n");
  41                 return -1;
  42         }
  43
  44         ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
  45         if (nr_blocks && ret == 0)
  46                 return -1;
  47
  48         return ret;
  49 }
  50
  51 /*
  52  * Set short name in directory entry
  53  */
  54 static void set_name(dir_entry *dirent, const char *filename)
  55 {
  56         char s_name[VFAT_MAXLEN_BYTES];
  57         char *period;
  58         int period_location, len, i, ext_num;
  59
  60         if (filename == NULL)
  61                 return;
  62
  63         len = strlen(filename);
  64         if (len == 0)
  65                 return;
  66
  67         strcpy(s_name, filename);
  68         uppercase(s_name, len);
  69
  70         period = strchr(s_name, '.');
  71         if (period == NULL) {
  72                 period_location = len;
  73                 ext_num = 0;
  74         } else {
  75                 period_location = period - s_name;
  76                 ext_num = len - period_location - 1;
  77         }
  78
  79         /* Pad spaces when the length of file name is shorter than eight */
  80         if (period_location < 8) {
  81                 memcpy(dirent->name, s_name, period_location);
  82                 for (i = period_location; i < 8; i++)
  83                         dirent->name[i] = ' ';
  84         } else if (period_location == 8) {
  85                 memcpy(dirent->name, s_name, period_location);
  86         } else {
  87                 memcpy(dirent->name, s_name, 6);
  88                 dirent->name[6] = '~';
  89                 dirent->name[7] = '1';
  90         }
  91
  92         if (ext_num < 3) {
  93                 memcpy(dirent->ext, s_name + period_location + 1, ext_num);
  94                 for (i = ext_num; i < 3; i++)
  95                         dirent->ext[i] = ' ';
  96         } else
  97                 memcpy(dirent->ext, s_name + period_location + 1, 3);
  98
  99         debug("name : %s\n", dirent->name);
 100         debug("ext : %s\n", dirent->ext);
 101 }
 102
 103 static __u8 num_of_fats;
 104 /*
 105  * Write fat buffer into block device
 106  */
 107 static int flush_dirty_fat_buffer(fsdata *mydata)
 108 {
 109         int getsize = FATBUFBLOCKS;
 110         __u32 fatlength = mydata->fatlength;
 111         __u8 *bufptr = mydata->fatbuf;
 112         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 113
 114         debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
 115               (int)mydata->fat_dirty);
 116
 117         if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
 118                 return 0;
 119
 120         startblock += mydata->fat_sect;
 121
 122         if (getsize > fatlength)
 123                 getsize = fatlength;
 124
 125         /* Write FAT buf */
 126         if (disk_write(startblock, getsize, bufptr) < 0) {
 127                 debug("error: writing FAT blocks\n");
 128                 return -1;
 129         }
 130
 131         if (num_of_fats == 2) {
 132                 /* Update corresponding second FAT blocks */
 133                 startblock += mydata->fatlength;
 134                 if (disk_write(startblock, getsize, bufptr) < 0) {
 135                         debug("error: writing second FAT blocks\n");
 136                         return -1;
 137                 }
 138         }
 139         mydata->fat_dirty = 0;
 140
 141         return 0;
 142 }
 143
 144 /*
 145  * Get the entry at index 'entry' in a FAT (12/16/32) table.
 146  * On failure 0x00 is returned.
 147  * When bufnum is changed, write back the previous fatbuf to the disk.
 148  */
 149 static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
 150 {
 151         __u32 bufnum;
 152         __u32 off16, offset;
 153         __u32 ret = 0x00;
 154         __u16 val1, val2;
 155
 156         if (CHECK_CLUST(entry, mydata->fatsize)) {
 157                 printf("Error: Invalid FAT entry: 0x%08x\n", entry);
 158                 return ret;
 159         }
 160
 161         switch (mydata->fatsize) {
 162         case 32:
 163                 bufnum = entry / FAT32BUFSIZE;
 164                 offset = entry - bufnum * FAT32BUFSIZE;
 165                 break;
 166         case 16:
 167                 bufnum = entry / FAT16BUFSIZE;
 168                 offset = entry - bufnum * FAT16BUFSIZE;
 169                 break;
 170         case 12:
 171                 bufnum = entry / FAT12BUFSIZE;
 172                 offset = entry - bufnum * FAT12BUFSIZE;
 173                 break;
 174
 175         default:
 176                 /* Unsupported FAT size */
 177                 return ret;
 178         }
 179
 180         debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
 181                mydata->fatsize, entry, entry, offset, offset);
 182
 183         /* Read a new block of FAT entries into the cache. */
 184         if (bufnum != mydata->fatbufnum) {
 185                 int getsize = FATBUFBLOCKS;
 186                 __u8 *bufptr = mydata->fatbuf;
 187                 __u32 fatlength = mydata->fatlength;
 188                 __u32 startblock = bufnum * FATBUFBLOCKS;
 189
 190                 if (getsize > fatlength)
 191                         getsize = fatlength;
 192
 193                 startblock += mydata->fat_sect; /* Offset from start of disk */
 194
 195                 /* Write back the fatbuf to the disk */
 196                 if (flush_dirty_fat_buffer(mydata) < 0)
 197                         return -1;
 198
 199                 if (disk_read(startblock, getsize, bufptr) < 0) {
 200                         debug("Error reading FAT blocks\n");
 201                         return ret;
 202                 }
 203                 mydata->fatbufnum = bufnum;
 204         }
 205
 206         /* Get the actual entry from the table */
 207         switch (mydata->fatsize) {
 208         case 32:
 209                 ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
 210                 break;
 211         case 16:
 212                 ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
 213                 break;
 214         case 12:
 215                 off16 = (offset * 3) / 4;
 216
 217                 switch (offset & 0x3) {
 218                 case 0:
 219                         ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
 220                         ret &= 0xfff;
 221                         break;
 222                 case 1:
 223                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 224                         val1 &= 0xf000;
 225                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 226                         val2 &= 0x00ff;
 227                         ret = (val2 << 4) | (val1 >> 12);
 228                         break;
 229                 case 2:
 230                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 231                         val1 &= 0xff00;
 232                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 233                         val2 &= 0x000f;
 234                         ret = (val2 << 8) | (val1 >> 8);
 235                         break;
 236                 case 3:
 237                         ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 238                         ret = (ret & 0xfff0) >> 4;
 239                         break;
 240                 default:
 241                         break;
 242                 }
 243                 break;
 244         }
 245         debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
 246                mydata->fatsize, ret, entry, offset);
 247
 248         return ret;
 249 }
 250
 251 /*
 252  * Set the file name information from 'name' into 'slotptr',
 253  */
 254 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 255 {
 256         int j, end_idx = 0;
 257
 258         for (j = 0; j <= 8; j += 2) {
 259                 if (name[*idx] == 0x00) {
 260                         slotptr->name0_4[j] = 0;
 261                         slotptr->name0_4[j + 1] = 0;
 262                         end_idx++;
 263                         goto name0_4;
 264                 }
 265                 slotptr->name0_4[j] = name[*idx];
 266                 (*idx)++;
 267                 end_idx++;
 268         }
 269         for (j = 0; j <= 10; j += 2) {
 270                 if (name[*idx] == 0x00) {
 271                         slotptr->name5_10[j] = 0;
 272                         slotptr->name5_10[j + 1] = 0;
 273                         end_idx++;
 274                         goto name5_10;
 275                 }
 276                 slotptr->name5_10[j] = name[*idx];
 277                 (*idx)++;
 278                 end_idx++;
 279         }
 280         for (j = 0; j <= 2; j += 2) {
 281                 if (name[*idx] == 0x00) {
 282                         slotptr->name11_12[j] = 0;
 283                         slotptr->name11_12[j + 1] = 0;
 284                         end_idx++;
 285                         goto name11_12;
 286                 }
 287                 slotptr->name11_12[j] = name[*idx];
 288                 (*idx)++;
 289                 end_idx++;
 290         }
 291
 292         if (name[*idx] == 0x00)
 293                 return 1;
 294
 295         return 0;
 296 /* Not used characters are filled with 0xff 0xff */
 297 name0_4:
 298         for (; end_idx < 5; end_idx++) {
 299                 slotptr->name0_4[end_idx * 2] = 0xff;
 300                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 301         }
 302         end_idx = 5;
 303 name5_10:
 304         end_idx -= 5;
 305         for (; end_idx < 6; end_idx++) {
 306                 slotptr->name5_10[end_idx * 2] = 0xff;
 307                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 308         }
 309         end_idx = 11;
 310 name11_12:
 311         end_idx -= 11;
 312         for (; end_idx < 2; end_idx++) {
 313                 slotptr->name11_12[end_idx * 2] = 0xff;
 314                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 315         }
 316
 317         return 1;
 318 }
 319
 320 static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
 321 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);
 322
 323 /*
 324  * Fill dir_slot entries with appropriate name, id, and attr
 325  * The real directory entry is returned by 'dentptr'
 326  */
 327 static void
 328 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 329 {
 330         __u8 temp_dir_slot_buffer[MAX_LFN_SLOT * sizeof(dir_slot)];
 331         dir_slot *slotptr = (dir_slot *)temp_dir_slot_buffer;
 332         __u8 counter = 0, checksum;
 333         int idx = 0, ret;
 334
 335         /* Get short file name checksum value */
 336         checksum = mkcksum((*dentptr)->name, (*dentptr)->ext);
 337
 338         do {
 339                 memset(slotptr, 0x00, sizeof(dir_slot));
 340                 ret = str2slot(slotptr, l_name, &idx);
 341                 slotptr->id = ++counter;
 342                 slotptr->attr = ATTR_VFAT;
 343                 slotptr->alias_checksum = checksum;
 344                 slotptr++;
 345         } while (ret == 0);
 346
 347         slotptr--;
 348         slotptr->id |= LAST_LONG_ENTRY_MASK;
 349
 350         while (counter >= 1) {
 351                 if (is_next_clust(mydata, *dentptr)) {
 352                         /* A new cluster is allocated for directory table */
 353                         flush_dir_table(mydata, dentptr);
 354                 }
 355                 memcpy(*dentptr, slotptr, sizeof(dir_slot));
 356                 (*dentptr)++;
 357                 slotptr--;
 358                 counter--;
 359         }
 360
 361         if (is_next_clust(mydata, *dentptr)) {
 362                 /* A new cluster is allocated for directory table */
 363                 flush_dir_table(mydata, dentptr);
 364         }
 365 }
 366
 367 static __u32 dir_curclust;
 368
 369 /*
 370  * Extract the full long filename starting at 'retdent' (which is really
 371  * a slot) into 'l_name'. If successful also copy the real directory entry
 372  * into 'retdent'
 373  * If additional adjacent cluster for directory entries is read into memory,
 374  * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and
 375  * the location of the real directory entry is returned by 'retdent'
 376  * Return 0 on success, -1 otherwise.
 377  */
 378 static int
 379 get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 380               dir_entry **retdent, char *l_name)
 381 {
 382         dir_entry *realdent;
 383         dir_slot *slotptr = (dir_slot *)(*retdent);
 384         dir_slot *slotptr2 = NULL;
 385         __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
 386                                                         PREFETCH_BLOCKS :
 387                                                         mydata->clust_size);
 388         __u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
 389         int idx = 0, cur_position = 0;
 390
 391         if (counter > VFAT_MAXSEQ) {
 392                 debug("Error: VFAT name is too long\n");
 393                 return -1;
 394         }
 395
 396         while ((__u8 *)slotptr < buflimit) {
 397                 if (counter == 0)
 398                         break;
 399                 if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
 400                         return -1;
 401                 slotptr++;
 402                 counter--;
 403         }
 404
 405         if ((__u8 *)slotptr >= buflimit) {
 406                 if (curclust == 0)
 407                         return -1;
 408                 curclust = get_fatent_value(mydata, dir_curclust);
 409                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 410                         debug("curclust: 0x%x\n", curclust);
 411                         printf("Invalid FAT entry\n");
 412                         return -1;
 413                 }
 414
 415                 dir_curclust = curclust;
 416
 417                 if (get_cluster(mydata, curclust, get_contents_vfatname_block,
 418                                 mydata->clust_size * mydata->sect_size) != 0) {
 419                         debug("Error: reading directory block\n");
 420                         return -1;
 421                 }
 422
 423                 slotptr2 = (dir_slot *)get_contents_vfatname_block;
 424                 while (counter > 0) {
 425                         if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
 426                             & 0xff) != counter)
 427                                 return -1;
 428                         slotptr2++;
 429                         counter--;
 430                 }
 431
 432                 /* Save the real directory entry */
 433                 realdent = (dir_entry *)slotptr2;
 434                 while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
 435                         slotptr2--;
 436                         slot2str(slotptr2, l_name, &idx);
 437                 }
 438         } else {
 439                 /* Save the real directory entry */
 440                 realdent = (dir_entry *)slotptr;
 441         }
 442
 443         do {
 444                 slotptr--;
 445                 if (slot2str(slotptr, l_name, &idx))
 446                         break;
 447         } while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
 448
 449         l_name[idx] = '\0';
 450         if (*l_name == DELETED_FLAG)
 451                 *l_name = '\0';
 452         else if (*l_name == aRING)
 453                 *l_name = DELETED_FLAG;
 454         downcase(l_name);
 455
 456         /* Return the real directory entry */
 457         *retdent = realdent;
 458
 459         if (slotptr2) {
 460                 memcpy(get_dentfromdir_block, get_contents_vfatname_block,
 461                         mydata->clust_size * mydata->sect_size);
 462                 cur_position = (__u8 *)realdent - get_contents_vfatname_block;
 463                 *retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
 464         }
 465
 466         return 0;
 467 }
 468
 469 /*
 470  * Set the entry at index 'entry' in a FAT (16/32) table.
 471  */
 472 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 473 {
 474         __u32 bufnum, offset;
 475
 476         switch (mydata->fatsize) {
 477         case 32:
 478                 bufnum = entry / FAT32BUFSIZE;
 479                 offset = entry - bufnum * FAT32BUFSIZE;
 480                 break;
 481         case 16:
 482                 bufnum = entry / FAT16BUFSIZE;
 483                 offset = entry - bufnum * FAT16BUFSIZE;
 484                 break;
 485         default:
 486                 /* Unsupported FAT size */
 487                 return -1;
 488         }
 489
 490         /* Read a new block of FAT entries into the cache. */
 491         if (bufnum != mydata->fatbufnum) {
 492                 int getsize = FATBUFBLOCKS;
 493                 __u8 *bufptr = mydata->fatbuf;
 494                 __u32 fatlength = mydata->fatlength;
 495                 __u32 startblock = bufnum * FATBUFBLOCKS;
 496
 497                 fatlength *= mydata->sect_size;
 498                 startblock += mydata->fat_sect;
 499
 500                 if (getsize > fatlength)
 501                         getsize = fatlength;
 502
 503                 if (flush_dirty_fat_buffer(mydata) < 0)
 504                         return -1;
 505
 506                 if (disk_read(startblock, getsize, bufptr) < 0) {
 507                         debug("Error reading FAT blocks\n");
 508                         return -1;
 509                 }
 510                 mydata->fatbufnum = bufnum;
 511         }
 512
 513         /* Mark as dirty */
 514         mydata->fat_dirty = 1;
 515
 516         /* Set the actual entry */
 517         switch (mydata->fatsize) {
 518         case 32:
 519                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 520                 break;
 521         case 16:
 522                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 523                 break;
 524         default:
 525                 return -1;
 526         }
 527
 528         return 0;
 529 }
 530
 531 /*
 532  * Determine the next free cluster after 'entry' in a FAT (16/32) table
 533  * and link it to 'entry'. EOC marker is not set on returned entry.
 534  */
 535 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 536 {
 537         __u32 next_fat, next_entry = entry + 1;
 538
 539         while (1) {
 540                 next_fat = get_fatent_value(mydata, next_entry);
 541                 if (next_fat == 0) {
 542                         /* found free entry, link to entry */
 543                         set_fatent_value(mydata, entry, next_entry);
 544                         break;
 545                 }
 546                 next_entry++;
 547         }
 548         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 549                mydata->fatsize, entry, next_entry);
 550
 551         return next_entry;
 552 }
 553
 554 /*
 555  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 556  * Return 0 on success, -1 otherwise.
 557  */
 558 static int
 559 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 560              unsigned long size)
 561 {
 562         __u32 idx = 0;
 563         __u32 startsect;
 564         int ret;
 565
 566         if (clustnum > 0)
 567                 startsect = mydata->data_begin +
 568                                 clustnum * mydata->clust_size;
 569         else
 570                 startsect = mydata->rootdir_sect;
 571
 572         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 573
 574         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 575                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 576
 577                 printf("FAT: Misaligned buffer address (%p)\n", buffer);
 578
 579                 while (size >= mydata->sect_size) {
 580                         memcpy(tmpbuf, buffer, mydata->sect_size);
 581                         ret = disk_write(startsect++, 1, tmpbuf);
 582                         if (ret != 1) {
 583                                 debug("Error writing data (got %d)\n", ret);
 584                                 return -1;
 585                         }
 586
 587                         buffer += mydata->sect_size;
 588                         size -= mydata->sect_size;
 589                 }
 590         } else if (size >= mydata->sect_size) {
 591                 idx = size / mydata->sect_size;
 592                 ret = disk_write(startsect, idx, buffer);
 593                 if (ret != idx) {
 594                         debug("Error writing data (got %d)\n", ret);
 595                         return -1;
 596                 }
 597
 598                 startsect += idx;
 599                 idx *= mydata->sect_size;
 600                 buffer += idx;
 601                 size -= idx;
 602         }
 603
 604         if (size) {
 605                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 606
 607                 memcpy(tmpbuf, buffer, size);
 608                 ret = disk_write(startsect, 1, tmpbuf);
 609                 if (ret != 1) {
 610                         debug("Error writing data (got %d)\n", ret);
 611                         return -1;
 612                 }
 613         }
 614
 615         return 0;
 616 }
 617
 618 /*
 619  * Find the first empty cluster
 620  */
 621 static int find_empty_cluster(fsdata *mydata)
 622 {
 623         __u32 fat_val, entry = 3;
 624
 625         while (1) {
 626                 fat_val = get_fatent_value(mydata, entry);
 627                 if (fat_val == 0)
 628                         break;
 629                 entry++;
 630         }
 631
 632         return entry;
 633 }
 634
 635 /*
 636  * Write directory entries in 'get_dentfromdir_block' to block device
 637  */
 638 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 639 {
 640         int dir_newclust = 0;
 641
 642         if (set_cluster(mydata, dir_curclust,
 643                     get_dentfromdir_block,
 644                     mydata->clust_size * mydata->sect_size) != 0) {
 645                 printf("error: wrinting directory entry\n");
 646                 return;
 647         }
 648         dir_newclust = find_empty_cluster(mydata);
 649         set_fatent_value(mydata, dir_curclust, dir_newclust);
 650         if (mydata->fatsize == 32)
 651                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 652         else if (mydata->fatsize == 16)
 653                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 654
 655         dir_curclust = dir_newclust;
 656
 657         if (flush_dirty_fat_buffer(mydata) < 0)
 658                 return;
 659
 660         memset(get_dentfromdir_block, 0x00,
 661                 mydata->clust_size * mydata->sect_size);
 662
 663         *dentptr = (dir_entry *) get_dentfromdir_block;
 664 }
 665
 666 /*
 667  * Set empty cluster from 'entry' to the end of a file
 668  */
 669 static int clear_fatent(fsdata *mydata, __u32 entry)
 670 {
 671         __u32 fat_val;
 672
 673         while (1) {
 674                 fat_val = get_fatent_value(mydata, entry);
 675                 if (fat_val != 0)
 676                         set_fatent_value(mydata, entry, 0);
 677                 else
 678                         break;
 679
 680                 if (fat_val == 0xfffffff || fat_val == 0xffff)
 681                         break;
 682
 683                 entry = fat_val;
 684         }
 685
 686         /* Flush fat buffer */
 687         if (flush_dirty_fat_buffer(mydata) < 0)
 688                 return -1;
 689
 690         return 0;
 691 }
 692
 693 /*
 694  * Write at most 'maxsize' bytes from 'buffer' into
 695  * the file associated with 'dentptr'
 696  * Update the number of bytes written in *gotsize and return 0
 697  * or return -1 on fatal errors.
 698  */
 699 static int
 700 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 701               loff_t maxsize, loff_t *gotsize)
 702 {
 703         loff_t filesize = FAT2CPU32(dentptr->size);
 704         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 705         __u32 curclust = START(dentptr);
 706         __u32 endclust = 0, newclust = 0;
 707         loff_t actsize;
 708
 709         *gotsize = 0;
 710         debug("Filesize: %llu bytes\n", filesize);
 711
 712         if (maxsize > 0 && filesize > maxsize)
 713                 filesize = maxsize;
 714
 715         debug("%llu bytes\n", filesize);
 716
 717         if (!curclust) {
 718                 if (filesize) {
 719                         debug("error: nonempty clusterless file!\n");
 720                         return -1;
 721                 }
 722                 return 0;
 723         }
 724
 725         actsize = bytesperclust;
 726         endclust = curclust;
 727         do {
 728                 /* search for consecutive clusters */
 729                 while (actsize < filesize) {
 730                         newclust = determine_fatent(mydata, endclust);
 731
 732                         if ((newclust - 1) != endclust)
 733                                 goto getit;
 734
 735                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 736                                 debug("newclust: 0x%x\n", newclust);
 737                                 debug("Invalid FAT entry\n");
 738                                 return 0;
 739                         }
 740                         endclust = newclust;
 741                         actsize += bytesperclust;
 742                 }
 743
 744                 /* set remaining bytes */
 745                 actsize = filesize;
 746                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 747                         debug("error: writing cluster\n");
 748                         return -1;
 749                 }
 750                 *gotsize += actsize;
 751
 752                 /* Mark end of file in FAT */
 753                 if (mydata->fatsize == 16)
 754                         newclust = 0xffff;
 755                 else if (mydata->fatsize == 32)
 756                         newclust = 0xfffffff;
 757                 set_fatent_value(mydata, endclust, newclust);
 758
 759                 return 0;
 760 getit:
 761                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 762                         debug("error: writing cluster\n");
 763                         return -1;
 764                 }
 765                 *gotsize += actsize;
 766                 filesize -= actsize;
 767                 buffer += actsize;
 768
 769                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 770                         debug("newclust: 0x%x\n", newclust);
 771                         debug("Invalid FAT entry\n");
 772                         return 0;
 773                 }
 774                 actsize = bytesperclust;
 775                 curclust = endclust = newclust;
 776         } while (1);
 777 }
 778
 779 /*
 780  * Set start cluster in directory entry
 781  */
 782 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 783                                 __u32 start_cluster)
 784 {
 785         if (mydata->fatsize == 32)
 786                 dentptr->starthi =
 787                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 788         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 789 }
 790
 791 /*
 792  * Fill dir_entry
 793  */
 794 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 795         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 796 {
 797         set_start_cluster(mydata, dentptr, start_cluster);
 798         dentptr->size = cpu_to_le32(size);
 799
 800         dentptr->attr = attr;
 801
 802         set_name(dentptr, filename);
 803 }
 804
 805 /*
 806  * Check whether adding a file makes the file system to
 807  * exceed the size of the block device
 808  * Return -1 when overflow occurs, otherwise return 0
 809  */
 810 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 811 {
 812         __u32 startsect, sect_num, offset;
 813
 814         if (clustnum > 0) {
 815                 startsect = mydata->data_begin +
 816                                 clustnum * mydata->clust_size;
 817         } else {
 818                 startsect = mydata->rootdir_sect;
 819         }
 820
 821         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 822
 823         if (offset != 0)
 824                 sect_num++;
 825
 826         if (startsect + sect_num > cur_part_info.start + total_sector)
 827                 return -1;
 828         return 0;
 829 }
 830
 831 /*
 832  * Check if adding several entries exceed one cluster boundary
 833  */
 834 static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
 835 {
 836         int cur_position;
 837
 838         cur_position = (__u8 *)dentptr - get_dentfromdir_block;
 839
 840         if (cur_position >= mydata->clust_size * mydata->sect_size)
 841                 return 1;
 842         else
 843                 return 0;
 844 }
 845
 846 static dir_entry *empty_dentptr;
 847 /*
 848  * Find a directory entry based on filename or start cluster number
 849  * If the directory entry is not found,
 850  * the new position for writing a directory entry will be returned
 851  */
 852 static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
 853         char *filename, dir_entry *retdent, __u32 start)
 854 {
 855         __u32 curclust = (startsect - mydata->data_begin) / mydata->clust_size;
 856
 857         debug("get_dentfromdir: %s\n", filename);
 858
 859         while (1) {
 860                 dir_entry *dentptr;
 861
 862                 int i;
 863
 864                 if (get_cluster(mydata, curclust, get_dentfromdir_block,
 865                             mydata->clust_size * mydata->sect_size) != 0) {
 866                         printf("Error: reading directory block\n");
 867                         return NULL;
 868                 }
 869
 870                 dentptr = (dir_entry *)get_dentfromdir_block;
 871
 872                 dir_curclust = curclust;
 873
 874                 for (i = 0; i < DIRENTSPERCLUST; i++) {
 875                         char s_name[14], l_name[VFAT_MAXLEN_BYTES];
 876
 877                         l_name[0] = '\0';
 878                         if (dentptr->name[0] == DELETED_FLAG) {
 879                                 dentptr++;
 880                                 if (is_next_clust(mydata, dentptr))
 881                                         break;
 882                                 continue;
 883                         }
 884                         if ((dentptr->attr & ATTR_VOLUME)) {
 885                                 if (vfat_enabled &&
 886                                     (dentptr->attr & ATTR_VFAT) &&
 887                                     (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
 888                                         get_long_file_name(mydata, curclust,
 889                                                      get_dentfromdir_block,
 890                                                      &dentptr, l_name);
 891                                         debug("vfatname: |%s|\n", l_name);
 892                                 } else {
 893                                         /* Volume label or VFAT entry */
 894                                         dentptr++;
 895                                         if (is_next_clust(mydata, dentptr))
 896                                                 break;
 897                                         continue;
 898                                 }
 899                         }
 900                         if (dentptr->name[0] == 0) {
 901                                 debug("Dentname == NULL - %d\n", i);
 902                                 empty_dentptr = dentptr;
 903                                 return NULL;
 904                         }
 905
 906                         get_name(dentptr, s_name);
 907
 908                         if (strcmp(filename, s_name)
 909                             && strcmp(filename, l_name)) {
 910                                 debug("Mismatch: |%s|%s|\n",
 911                                         s_name, l_name);
 912                                 dentptr++;
 913                                 if (is_next_clust(mydata, dentptr))
 914                                         break;
 915                                 continue;
 916                         }
 917
 918                         memcpy(retdent, dentptr, sizeof(dir_entry));
 919
 920                         debug("DentName: %s", s_name);
 921                         debug(", start: 0x%x", START(dentptr));
 922                         debug(", size:  0x%x %s\n",
 923                               FAT2CPU32(dentptr->size),
 924                               (dentptr->attr & ATTR_DIR) ?
 925                               "(DIR)" : "");
 926
 927                         return dentptr;
 928                 }
 929
 930                 /*
 931                  * In FAT16/12, the root dir is locate before data area, shows
 932                  * in following:
 933                  * -------------------------------------------------------------
 934                  * | Boot | FAT1 & 2 | Root dir | Data (start from cluster #2) |
 935                  * -------------------------------------------------------------
 936                  *
 937                  * As a result if curclust is in Root dir, it is a negative
 938                  * number or 0, 1.
 939                  *
 940                  */
 941                 if (mydata->fatsize != 32 && (int)curclust <= 1) {
 942                         /* Current clust is in root dir, set to next clust */
 943                         curclust++;
 944                         if ((int)curclust <= 1)
 945                                 continue;       /* continue to find */
 946
 947                         /* Reach the end of root dir */
 948                         empty_dentptr = dentptr;
 949                         return NULL;
 950                 }
 951
 952                 curclust = get_fatent_value(mydata, dir_curclust);
 953                 if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 954                         empty_dentptr = dentptr;
 955                         return NULL;
 956                 }
 957                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 958                         debug("curclust: 0x%x\n", curclust);
 959                         debug("Invalid FAT entry\n");
 960                         return NULL;
 961                 }
 962         }
 963
 964         return NULL;
 965 }
 966
 967 static int do_fat_write(const char *filename, void *buffer, loff_t size,
 968                         loff_t *actwrite)
 969 {
 970         dir_entry *dentptr, *retdent;
 971         __u32 startsect;
 972         __u32 start_cluster;
 973         boot_sector bs;
 974         volume_info volinfo;
 975         fsdata datablock;
 976         fsdata *mydata = &datablock;
 977         int cursect;
 978         int ret = -1, name_len;
 979         char l_filename[VFAT_MAXLEN_BYTES];
 980
 981         *actwrite = size;
 982         dir_curclust = 0;
 983
 984         if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
 985                 debug("error: reading boot sector\n");
 986                 return -1;
 987         }
 988
 989         total_sector = bs.total_sect;
 990         if (total_sector == 0)
 991                 total_sector = (int)cur_part_info.size; /* cast of lbaint_t */
 992
 993         if (mydata->fatsize == 32)
 994                 mydata->fatlength = bs.fat32_length;
 995         else
 996                 mydata->fatlength = bs.fat_length;
 997
 998         mydata->fat_sect = bs.reserved;
 999
1000         cursect = mydata->rootdir_sect
1001                 = mydata->fat_sect + mydata->fatlength * bs.fats;
1002         num_of_fats = bs.fats;
1003
1004         mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
1005         mydata->clust_size = bs.cluster_size;
1006
1007         if (mydata->fatsize == 32) {
1008                 mydata->data_begin = mydata->rootdir_sect -
1009                                         (mydata->clust_size * 2);
1010         } else {
1011                 int rootdir_size;
1012
1013                 rootdir_size = ((bs.dir_entries[1]  * (int)256 +
1014                                  bs.dir_entries[0]) *
1015                                  sizeof(dir_entry)) /
1016                                  mydata->sect_size;
1017                 mydata->data_begin = mydata->rootdir_sect +
1018                                         rootdir_size -
1019                                         (mydata->clust_size * 2);
1020         }
1021
1022         mydata->fatbufnum = -1;
1023         mydata->fat_dirty = 0;
1024         mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
1025         if (mydata->fatbuf == NULL) {
1026                 debug("Error: allocating memory\n");
1027                 return -1;
1028         }
1029
1030         if (disk_read(cursect,
1031                 (mydata->fatsize == 32) ?
1032                 (mydata->clust_size) :
1033                 PREFETCH_BLOCKS, do_fat_read_at_block) < 0) {
1034                 debug("Error: reading rootdir block\n");
1035                 goto exit;
1036         }
1037         dentptr = (dir_entry *) do_fat_read_at_block;
1038
1039         name_len = strlen(filename);
1040         if (name_len >= VFAT_MAXLEN_BYTES)
1041                 name_len = VFAT_MAXLEN_BYTES - 1;
1042
1043         memcpy(l_filename, filename, name_len);
1044         l_filename[name_len] = 0; /* terminate the string */
1045         downcase(l_filename);
1046
1047         startsect = mydata->rootdir_sect;
1048         retdent = find_directory_entry(mydata, startsect,
1049                                 l_filename, dentptr, 0);
1050         if (retdent) {
1051                 /* Update file size and start_cluster in a directory entry */
1052                 retdent->size = cpu_to_le32(size);
1053                 start_cluster = START(retdent);
1054
1055                 if (start_cluster) {
1056                         if (size) {
1057                                 ret = check_overflow(mydata, start_cluster,
1058                                                         size);
1059                                 if (ret) {
1060                                         printf("Error: %llu overflow\n", size);
1061                                         goto exit;
1062                                 }
1063                         }
1064
1065                         ret = clear_fatent(mydata, start_cluster);
1066                         if (ret) {
1067                                 printf("Error: clearing FAT entries\n");
1068                                 goto exit;
1069                         }
1070
1071                         if (!size)
1072                                 set_start_cluster(mydata, retdent, 0);
1073                 } else if (size) {
1074                         ret = start_cluster = find_empty_cluster(mydata);
1075                         if (ret < 0) {
1076                                 printf("Error: finding empty cluster\n");
1077                                 goto exit;
1078                         }
1079
1080                         ret = check_overflow(mydata, start_cluster, size);
1081                         if (ret) {
1082                                 printf("Error: %llu overflow\n", size);
1083                                 goto exit;
1084                         }
1085
1086                         set_start_cluster(mydata, retdent, start_cluster);
1087                 }
1088         } else {
1089                 /* Set short name to set alias checksum field in dir_slot */
1090                 set_name(empty_dentptr, filename);
1091                 fill_dir_slot(mydata, &empty_dentptr, filename);
1092
1093                 if (size) {
1094                         ret = start_cluster = find_empty_cluster(mydata);
1095                         if (ret < 0) {
1096                                 printf("Error: finding empty cluster\n");
1097                                 goto exit;
1098                         }
1099
1100                         ret = check_overflow(mydata, start_cluster, size);
1101                         if (ret) {
1102                                 printf("Error: %llu overflow\n", size);
1103                                 goto exit;
1104                         }
1105                 } else {
1106                         start_cluster = 0;
1107                 }
1108
1109                 /* Set attribute as archieve for regular file */
1110                 fill_dentry(mydata, empty_dentptr, filename,
1111                         start_cluster, size, 0x20);
1112
1113                 retdent = empty_dentptr;
1114         }
1115
1116         ret = set_contents(mydata, retdent, buffer, size, actwrite);
1117         if (ret < 0) {
1118                 printf("Error: writing contents\n");
1119                 goto exit;
1120         }
1121         debug("attempt to write 0x%llx bytes\n", *actwrite);
1122
1123         /* Flush fat buffer */
1124         ret = flush_dirty_fat_buffer(mydata);
1125         if (ret) {
1126                 printf("Error: flush fat buffer\n");
1127                 goto exit;
1128         }
1129
1130         /* Write directory table to device */
1131         ret = set_cluster(mydata, dir_curclust, get_dentfromdir_block,
1132                         mydata->clust_size * mydata->sect_size);
1133         if (ret)
1134                 printf("Error: writing directory entry\n");
1135
1136 exit:
1137         free(mydata->fatbuf);
1138         return ret;
1139 }
1140
1141 int file_fat_write(const char *filename, void *buffer, loff_t offset,
1142                    loff_t maxsize, loff_t *actwrite)
1143 {
1144         if (offset != 0) {
1145                 printf("Error: non zero offset is currently not supported.\n");
1146                 return -1;
1147         }
1148
1149         printf("writing %s\n", filename);
1150         return do_fat_write(filename, buffer, maxsize, actwrite);
1151 }