fs/fat/fat_write.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * fat_write.c
   4  *
   5  * R/W (V)FAT 12/16/32 filesystem implementation by Donggeun Kim
   6  */
   7
   8 #include <common.h>
   9 #include <command.h>
  10 #include <config.h>
  11 #include <fat.h>
  12 #include <asm/byteorder.h>
  13 #include <part.h>
  14 #include <linux/ctype.h>
  15 #include <div64.h>
  16 #include <linux/math64.h>
  17 #include "fat.c"
  18
  19 static void uppercase(char *str, int len)
  20 {
  21         int i;
  22
  23         for (i = 0; i < len; i++) {
  24                 *str = toupper(*str);
  25                 str++;
  26         }
  27 }
  28
  29 static int total_sector;
  30 static int disk_write(__u32 block, __u32 nr_blocks, void *buf)
  31 {
  32         ulong ret;
  33
  34         if (!cur_dev)
  35                 return -1;
  36
  37         if (cur_part_info.start + block + nr_blocks >
  38                 cur_part_info.start + total_sector) {
  39                 printf("error: overflow occurs\n");
  40                 return -1;
  41         }
  42
  43         ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
  44         if (nr_blocks && ret == 0)
  45                 return -1;
  46
  47         return ret;
  48 }
  49
  50 /*
  51  * Set short name in directory entry
  52  */
  53 static void set_name(dir_entry *dirent, const char *filename)
  54 {
  55         char s_name[VFAT_MAXLEN_BYTES];
  56         char *period;
  57         int period_location, len, i, ext_num;
  58
  59         if (filename == NULL)
  60                 return;
  61
  62         len = strlen(filename);
  63         if (len == 0)
  64                 return;
  65
  66         strcpy(s_name, filename);
  67         uppercase(s_name, len);
  68
  69         period = strchr(s_name, '.');
  70         if (period == NULL) {
  71                 period_location = len;
  72                 ext_num = 0;
  73         } else {
  74                 period_location = period - s_name;
  75                 ext_num = len - period_location - 1;
  76         }
  77
  78         /* Pad spaces when the length of file name is shorter than eight */
  79         if (period_location < 8) {
  80                 memcpy(dirent->name, s_name, period_location);
  81                 for (i = period_location; i < 8; i++)
  82                         dirent->name[i] = ' ';
  83         } else if (period_location == 8) {
  84                 memcpy(dirent->name, s_name, period_location);
  85         } else {
  86                 memcpy(dirent->name, s_name, 6);
  87                 dirent->name[6] = '~';
  88                 dirent->name[7] = '1';
  89         }
  90
  91         if (ext_num < 3) {
  92                 memcpy(dirent->ext, s_name + period_location + 1, ext_num);
  93                 for (i = ext_num; i < 3; i++)
  94                         dirent->ext[i] = ' ';
  95         } else
  96                 memcpy(dirent->ext, s_name + period_location + 1, 3);
  97
  98         debug("name : %s\n", dirent->name);
  99         debug("ext : %s\n", dirent->ext);
 100 }
 101
 102 static __u8 num_of_fats;
 103 /*
 104  * Write fat buffer into block device
 105  */
 106 static int flush_dirty_fat_buffer(fsdata *mydata)
 107 {
 108         int getsize = FATBUFBLOCKS;
 109         __u32 fatlength = mydata->fatlength;
 110         __u8 *bufptr = mydata->fatbuf;
 111         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 112
 113         debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
 114               (int)mydata->fat_dirty);
 115
 116         if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
 117                 return 0;
 118
 119         /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 120         if (startblock + getsize > fatlength)
 121                 getsize = fatlength - startblock;
 122
 123         startblock += mydata->fat_sect;
 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  * Set the file name information from 'name' into 'slotptr',
 146  */
 147 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 148 {
 149         int j, end_idx = 0;
 150
 151         for (j = 0; j <= 8; j += 2) {
 152                 if (name[*idx] == 0x00) {
 153                         slotptr->name0_4[j] = 0;
 154                         slotptr->name0_4[j + 1] = 0;
 155                         end_idx++;
 156                         goto name0_4;
 157                 }
 158                 slotptr->name0_4[j] = name[*idx];
 159                 (*idx)++;
 160                 end_idx++;
 161         }
 162         for (j = 0; j <= 10; j += 2) {
 163                 if (name[*idx] == 0x00) {
 164                         slotptr->name5_10[j] = 0;
 165                         slotptr->name5_10[j + 1] = 0;
 166                         end_idx++;
 167                         goto name5_10;
 168                 }
 169                 slotptr->name5_10[j] = name[*idx];
 170                 (*idx)++;
 171                 end_idx++;
 172         }
 173         for (j = 0; j <= 2; j += 2) {
 174                 if (name[*idx] == 0x00) {
 175                         slotptr->name11_12[j] = 0;
 176                         slotptr->name11_12[j + 1] = 0;
 177                         end_idx++;
 178                         goto name11_12;
 179                 }
 180                 slotptr->name11_12[j] = name[*idx];
 181                 (*idx)++;
 182                 end_idx++;
 183         }
 184
 185         if (name[*idx] == 0x00)
 186                 return 1;
 187
 188         return 0;
 189 /* Not used characters are filled with 0xff 0xff */
 190 name0_4:
 191         for (; end_idx < 5; end_idx++) {
 192                 slotptr->name0_4[end_idx * 2] = 0xff;
 193                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 194         }
 195         end_idx = 5;
 196 name5_10:
 197         end_idx -= 5;
 198         for (; end_idx < 6; end_idx++) {
 199                 slotptr->name5_10[end_idx * 2] = 0xff;
 200                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 201         }
 202         end_idx = 11;
 203 name11_12:
 204         end_idx -= 11;
 205         for (; end_idx < 2; end_idx++) {
 206                 slotptr->name11_12[end_idx * 2] = 0xff;
 207                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 208         }
 209
 210         return 1;
 211 }
 212
 213 static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
 214 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);
 215
 216 /*
 217  * Fill dir_slot entries with appropriate name, id, and attr
 218  * The real directory entry is returned by 'dentptr'
 219  */
 220 static void
 221 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 222 {
 223         __u8 temp_dir_slot_buffer[MAX_LFN_SLOT * sizeof(dir_slot)];
 224         dir_slot *slotptr = (dir_slot *)temp_dir_slot_buffer;
 225         __u8 counter = 0, checksum;
 226         int idx = 0, ret;
 227
 228         /* Get short file name checksum value */
 229         checksum = mkcksum((*dentptr)->name, (*dentptr)->ext);
 230
 231         do {
 232                 memset(slotptr, 0x00, sizeof(dir_slot));
 233                 ret = str2slot(slotptr, l_name, &idx);
 234                 slotptr->id = ++counter;
 235                 slotptr->attr = ATTR_VFAT;
 236                 slotptr->alias_checksum = checksum;
 237                 slotptr++;
 238         } while (ret == 0);
 239
 240         slotptr--;
 241         slotptr->id |= LAST_LONG_ENTRY_MASK;
 242
 243         while (counter >= 1) {
 244                 if (is_next_clust(mydata, *dentptr)) {
 245                         /* A new cluster is allocated for directory table */
 246                         flush_dir_table(mydata, dentptr);
 247                 }
 248                 memcpy(*dentptr, slotptr, sizeof(dir_slot));
 249                 (*dentptr)++;
 250                 slotptr--;
 251                 counter--;
 252         }
 253
 254         if (is_next_clust(mydata, *dentptr)) {
 255                 /* A new cluster is allocated for directory table */
 256                 flush_dir_table(mydata, dentptr);
 257         }
 258 }
 259
 260 static __u32 dir_curclust;
 261
 262 /*
 263  * Extract the full long filename starting at 'retdent' (which is really
 264  * a slot) into 'l_name'. If successful also copy the real directory entry
 265  * into 'retdent'
 266  * If additional adjacent cluster for directory entries is read into memory,
 267  * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and
 268  * the location of the real directory entry is returned by 'retdent'
 269  * Return 0 on success, -1 otherwise.
 270  */
 271 static int
 272 get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 273               dir_entry **retdent, char *l_name)
 274 {
 275         dir_entry *realdent;
 276         dir_slot *slotptr = (dir_slot *)(*retdent);
 277         dir_slot *slotptr2 = NULL;
 278         __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
 279                                                         PREFETCH_BLOCKS :
 280                                                         mydata->clust_size);
 281         __u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
 282         int idx = 0, cur_position = 0;
 283
 284         if (counter > VFAT_MAXSEQ) {
 285                 debug("Error: VFAT name is too long\n");
 286                 return -1;
 287         }
 288
 289         while ((__u8 *)slotptr < buflimit) {
 290                 if (counter == 0)
 291                         break;
 292                 if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
 293                         return -1;
 294                 slotptr++;
 295                 counter--;
 296         }
 297
 298         if ((__u8 *)slotptr >= buflimit) {
 299                 if (curclust == 0)
 300                         return -1;
 301                 curclust = get_fatent(mydata, dir_curclust);
 302                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 303                         debug("curclust: 0x%x\n", curclust);
 304                         printf("Invalid FAT entry\n");
 305                         return -1;
 306                 }
 307
 308                 dir_curclust = curclust;
 309
 310                 if (get_cluster(mydata, curclust, get_contents_vfatname_block,
 311                                 mydata->clust_size * mydata->sect_size) != 0) {
 312                         debug("Error: reading directory block\n");
 313                         return -1;
 314                 }
 315
 316                 slotptr2 = (dir_slot *)get_contents_vfatname_block;
 317                 while (counter > 0) {
 318                         if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
 319                             & 0xff) != counter)
 320                                 return -1;
 321                         slotptr2++;
 322                         counter--;
 323                 }
 324
 325                 /* Save the real directory entry */
 326                 realdent = (dir_entry *)slotptr2;
 327                 while ((__u8 *)slotptr2 > get_contents_vfatname_block) {
 328                         slotptr2--;
 329                         slot2str(slotptr2, l_name, &idx);
 330                 }
 331         } else {
 332                 /* Save the real directory entry */
 333                 realdent = (dir_entry *)slotptr;
 334         }
 335
 336         do {
 337                 slotptr--;
 338                 if (slot2str(slotptr, l_name, &idx))
 339                         break;
 340         } while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
 341
 342         l_name[idx] = '\0';
 343         if (*l_name == DELETED_FLAG)
 344                 *l_name = '\0';
 345         else if (*l_name == aRING)
 346                 *l_name = DELETED_FLAG;
 347         downcase(l_name, INT_MAX);
 348
 349         /* Return the real directory entry */
 350         *retdent = realdent;
 351
 352         if (slotptr2) {
 353                 memcpy(get_dentfromdir_block, get_contents_vfatname_block,
 354                         mydata->clust_size * mydata->sect_size);
 355                 cur_position = (__u8 *)realdent - get_contents_vfatname_block;
 356                 *retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
 357         }
 358
 359         return 0;
 360 }
 361
 362 /*
 363  * Set the entry at index 'entry' in a FAT (12/16/32) table.
 364  */
 365 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 366 {
 367         __u32 bufnum, offset, off16;
 368         __u16 val1, val2;
 369
 370         switch (mydata->fatsize) {
 371         case 32:
 372                 bufnum = entry / FAT32BUFSIZE;
 373                 offset = entry - bufnum * FAT32BUFSIZE;
 374                 break;
 375         case 16:
 376                 bufnum = entry / FAT16BUFSIZE;
 377                 offset = entry - bufnum * FAT16BUFSIZE;
 378                 break;
 379         case 12:
 380                 bufnum = entry / FAT12BUFSIZE;
 381                 offset = entry - bufnum * FAT12BUFSIZE;
 382                 break;
 383         default:
 384                 /* Unsupported FAT size */
 385                 return -1;
 386         }
 387
 388         /* Read a new block of FAT entries into the cache. */
 389         if (bufnum != mydata->fatbufnum) {
 390                 int getsize = FATBUFBLOCKS;
 391                 __u8 *bufptr = mydata->fatbuf;
 392                 __u32 fatlength = mydata->fatlength;
 393                 __u32 startblock = bufnum * FATBUFBLOCKS;
 394
 395                 /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 396                 if (startblock + getsize > fatlength)
 397                         getsize = fatlength - startblock;
 398
 399                 if (flush_dirty_fat_buffer(mydata) < 0)
 400                         return -1;
 401
 402                 startblock += mydata->fat_sect;
 403
 404                 if (disk_read(startblock, getsize, bufptr) < 0) {
 405                         debug("Error reading FAT blocks\n");
 406                         return -1;
 407                 }
 408                 mydata->fatbufnum = bufnum;
 409         }
 410
 411         /* Mark as dirty */
 412         mydata->fat_dirty = 1;
 413
 414         /* Set the actual entry */
 415         switch (mydata->fatsize) {
 416         case 32:
 417                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 418                 break;
 419         case 16:
 420                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 421                 break;
 422         case 12:
 423                 off16 = (offset * 3) / 4;
 424
 425                 switch (offset & 0x3) {
 426                 case 0:
 427                         val1 = cpu_to_le16(entry_value) & 0xfff;
 428                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff;
 429                         ((__u16 *)mydata->fatbuf)[off16] |= val1;
 430                         break;
 431                 case 1:
 432                         val1 = cpu_to_le16(entry_value) & 0xf;
 433                         val2 = (cpu_to_le16(entry_value) >> 4) & 0xff;
 434
 435                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xf000;
 436                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 12);
 437
 438                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xff;
 439                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 440                         break;
 441                 case 2:
 442                         val1 = cpu_to_le16(entry_value) & 0xff;
 443                         val2 = (cpu_to_le16(entry_value) >> 8) & 0xf;
 444
 445                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xff00;
 446                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 8);
 447
 448                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xf;
 449                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 450                         break;
 451                 case 3:
 452                         val1 = cpu_to_le16(entry_value) & 0xfff;
 453                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff0;
 454                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 4);
 455                         break;
 456                 default:
 457                         break;
 458                 }
 459
 460                 break;
 461         default:
 462                 return -1;
 463         }
 464
 465         return 0;
 466 }
 467
 468 /*
 469  * Determine the next free cluster after 'entry' in a FAT (12/16/32) table
 470  * and link it to 'entry'. EOC marker is not set on returned entry.
 471  */
 472 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 473 {
 474         __u32 next_fat, next_entry = entry + 1;
 475
 476         while (1) {
 477                 next_fat = get_fatent(mydata, next_entry);
 478                 if (next_fat == 0) {
 479                         /* found free entry, link to entry */
 480                         set_fatent_value(mydata, entry, next_entry);
 481                         break;
 482                 }
 483                 next_entry++;
 484         }
 485         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 486                mydata->fatsize, entry, next_entry);
 487
 488         return next_entry;
 489 }
 490
 491 /*
 492  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 493  * Return 0 on success, -1 otherwise.
 494  */
 495 static int
 496 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 497              unsigned long size)
 498 {
 499         __u32 idx = 0;
 500         __u32 startsect;
 501         int ret;
 502
 503         if (clustnum > 0)
 504                 startsect = clust_to_sect(mydata, clustnum);
 505         else
 506                 startsect = mydata->rootdir_sect;
 507
 508         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 509
 510         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 511                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 512
 513                 printf("FAT: Misaligned buffer address (%p)\n", buffer);
 514
 515                 while (size >= mydata->sect_size) {
 516                         memcpy(tmpbuf, buffer, mydata->sect_size);
 517                         ret = disk_write(startsect++, 1, tmpbuf);
 518                         if (ret != 1) {
 519                                 debug("Error writing data (got %d)\n", ret);
 520                                 return -1;
 521                         }
 522
 523                         buffer += mydata->sect_size;
 524                         size -= mydata->sect_size;
 525                 }
 526         } else if (size >= mydata->sect_size) {
 527                 idx = size / mydata->sect_size;
 528                 ret = disk_write(startsect, idx, buffer);
 529                 if (ret != idx) {
 530                         debug("Error writing data (got %d)\n", ret);
 531                         return -1;
 532                 }
 533
 534                 startsect += idx;
 535                 idx *= mydata->sect_size;
 536                 buffer += idx;
 537                 size -= idx;
 538         }
 539
 540         if (size) {
 541                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 542
 543                 memcpy(tmpbuf, buffer, size);
 544                 ret = disk_write(startsect, 1, tmpbuf);
 545                 if (ret != 1) {
 546                         debug("Error writing data (got %d)\n", ret);
 547                         return -1;
 548                 }
 549         }
 550
 551         return 0;
 552 }
 553
 554 /*
 555  * Find the first empty cluster
 556  */
 557 static int find_empty_cluster(fsdata *mydata)
 558 {
 559         __u32 fat_val, entry = 3;
 560
 561         while (1) {
 562                 fat_val = get_fatent(mydata, entry);
 563                 if (fat_val == 0)
 564                         break;
 565                 entry++;
 566         }
 567
 568         return entry;
 569 }
 570
 571 /*
 572  * Write directory entries in 'get_dentfromdir_block' to block device
 573  */
 574 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 575 {
 576         int dir_newclust = 0;
 577
 578         if (set_cluster(mydata, dir_curclust,
 579                     get_dentfromdir_block,
 580                     mydata->clust_size * mydata->sect_size) != 0) {
 581                 printf("error: wrinting directory entry\n");
 582                 return;
 583         }
 584         dir_newclust = find_empty_cluster(mydata);
 585         set_fatent_value(mydata, dir_curclust, dir_newclust);
 586         if (mydata->fatsize == 32)
 587                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 588         else if (mydata->fatsize == 16)
 589                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 590         else if (mydata->fatsize == 12)
 591                 set_fatent_value(mydata, dir_newclust, 0xff8);
 592
 593         dir_curclust = dir_newclust;
 594
 595         if (flush_dirty_fat_buffer(mydata) < 0)
 596                 return;
 597
 598         memset(get_dentfromdir_block, 0x00,
 599                 mydata->clust_size * mydata->sect_size);
 600
 601         *dentptr = (dir_entry *) get_dentfromdir_block;
 602 }
 603
 604 /*
 605  * Set empty cluster from 'entry' to the end of a file
 606  */
 607 static int clear_fatent(fsdata *mydata, __u32 entry)
 608 {
 609         __u32 fat_val;
 610
 611         while (!CHECK_CLUST(entry, mydata->fatsize)) {
 612                 fat_val = get_fatent(mydata, entry);
 613                 if (fat_val != 0)
 614                         set_fatent_value(mydata, entry, 0);
 615                 else
 616                         break;
 617
 618                 entry = fat_val;
 619         }
 620
 621         /* Flush fat buffer */
 622         if (flush_dirty_fat_buffer(mydata) < 0)
 623                 return -1;
 624
 625         return 0;
 626 }
 627
 628 /*
 629  * Write at most 'maxsize' bytes from 'buffer' into
 630  * the file associated with 'dentptr'
 631  * Update the number of bytes written in *gotsize and return 0
 632  * or return -1 on fatal errors.
 633  */
 634 static int
 635 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 636               loff_t maxsize, loff_t *gotsize)
 637 {
 638         loff_t filesize = FAT2CPU32(dentptr->size);
 639         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 640         __u32 curclust = START(dentptr);
 641         __u32 endclust = 0, newclust = 0;
 642         loff_t actsize;
 643
 644         *gotsize = 0;
 645         debug("Filesize: %llu bytes\n", filesize);
 646
 647         if (maxsize > 0 && filesize > maxsize)
 648                 filesize = maxsize;
 649
 650         debug("%llu bytes\n", filesize);
 651
 652         if (!curclust) {
 653                 if (filesize) {
 654                         debug("error: nonempty clusterless file!\n");
 655                         return -1;
 656                 }
 657                 return 0;
 658         }
 659
 660         actsize = bytesperclust;
 661         endclust = curclust;
 662         do {
 663                 /* search for consecutive clusters */
 664                 while (actsize < filesize) {
 665                         newclust = determine_fatent(mydata, endclust);
 666
 667                         if ((newclust - 1) != endclust)
 668                                 goto getit;
 669
 670                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 671                                 debug("newclust: 0x%x\n", newclust);
 672                                 debug("Invalid FAT entry\n");
 673                                 return 0;
 674                         }
 675                         endclust = newclust;
 676                         actsize += bytesperclust;
 677                 }
 678
 679                 /* set remaining bytes */
 680                 actsize = filesize;
 681                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 682                         debug("error: writing cluster\n");
 683                         return -1;
 684                 }
 685                 *gotsize += actsize;
 686
 687                 /* Mark end of file in FAT */
 688                 if (mydata->fatsize == 12)
 689                         newclust = 0xfff;
 690                 else if (mydata->fatsize == 16)
 691                         newclust = 0xffff;
 692                 else if (mydata->fatsize == 32)
 693                         newclust = 0xfffffff;
 694                 set_fatent_value(mydata, endclust, newclust);
 695
 696                 return 0;
 697 getit:
 698                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 699                         debug("error: writing cluster\n");
 700                         return -1;
 701                 }
 702                 *gotsize += actsize;
 703                 filesize -= actsize;
 704                 buffer += actsize;
 705
 706                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 707                         debug("newclust: 0x%x\n", newclust);
 708                         debug("Invalid FAT entry\n");
 709                         return 0;
 710                 }
 711                 actsize = bytesperclust;
 712                 curclust = endclust = newclust;
 713         } while (1);
 714 }
 715
 716 /*
 717  * Set start cluster in directory entry
 718  */
 719 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 720                                 __u32 start_cluster)
 721 {
 722         if (mydata->fatsize == 32)
 723                 dentptr->starthi =
 724                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 725         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 726 }
 727
 728 /*
 729  * Fill dir_entry
 730  */
 731 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 732         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 733 {
 734         set_start_cluster(mydata, dentptr, start_cluster);
 735         dentptr->size = cpu_to_le32(size);
 736
 737         dentptr->attr = attr;
 738
 739         set_name(dentptr, filename);
 740 }
 741
 742 /*
 743  * Check whether adding a file makes the file system to
 744  * exceed the size of the block device
 745  * Return -1 when overflow occurs, otherwise return 0
 746  */
 747 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 748 {
 749         __u32 startsect, sect_num, offset;
 750
 751         if (clustnum > 0) {
 752                 startsect = clust_to_sect(mydata, clustnum);
 753         } else {
 754                 startsect = mydata->rootdir_sect;
 755         }
 756
 757         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 758
 759         if (offset != 0)
 760                 sect_num++;
 761
 762         if (startsect + sect_num > total_sector)
 763                 return -1;
 764         return 0;
 765 }
 766
 767 /*
 768  * Check if adding several entries exceed one cluster boundary
 769  */
 770 static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
 771 {
 772         int cur_position;
 773
 774         cur_position = (__u8 *)dentptr - get_dentfromdir_block;
 775
 776         if (cur_position >= mydata->clust_size * mydata->sect_size)
 777                 return 1;
 778         else
 779                 return 0;
 780 }
 781
 782 static dir_entry *empty_dentptr;
 783 /*
 784  * Find a directory entry based on filename or start cluster number
 785  * If the directory entry is not found,
 786  * the new position for writing a directory entry will be returned
 787  */
 788 static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
 789         char *filename, dir_entry *retdent, __u32 start)
 790 {
 791         __u32 curclust = sect_to_clust(mydata, startsect);
 792
 793         debug("get_dentfromdir: %s\n", filename);
 794
 795         while (1) {
 796                 dir_entry *dentptr;
 797
 798                 int i;
 799
 800                 if (get_cluster(mydata, curclust, get_dentfromdir_block,
 801                             mydata->clust_size * mydata->sect_size) != 0) {
 802                         printf("Error: reading directory block\n");
 803                         return NULL;
 804                 }
 805
 806                 dentptr = (dir_entry *)get_dentfromdir_block;
 807
 808                 dir_curclust = curclust;
 809
 810                 for (i = 0; i < DIRENTSPERCLUST; i++) {
 811                         char s_name[14], l_name[VFAT_MAXLEN_BYTES];
 812
 813                         l_name[0] = '\0';
 814                         if (dentptr->name[0] == DELETED_FLAG) {
 815                                 dentptr++;
 816                                 if (is_next_clust(mydata, dentptr))
 817                                         break;
 818                                 continue;
 819                         }
 820                         if ((dentptr->attr & ATTR_VOLUME)) {
 821                                 if ((dentptr->attr & ATTR_VFAT) &&
 822                                     (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
 823                                         get_long_file_name(mydata, curclust,
 824                                                      get_dentfromdir_block,
 825                                                      &dentptr, l_name);
 826                                         debug("vfatname: |%s|\n", l_name);
 827                                 } else {
 828                                         /* Volume label or VFAT entry */
 829                                         dentptr++;
 830                                         if (is_next_clust(mydata, dentptr))
 831                                                 break;
 832                                         continue;
 833                                 }
 834                         }
 835                         if (dentptr->name[0] == 0) {
 836                                 debug("Dentname == NULL - %d\n", i);
 837                                 empty_dentptr = dentptr;
 838                                 return NULL;
 839                         }
 840
 841                         get_name(dentptr, s_name);
 842
 843                         if (strncasecmp(filename, s_name, sizeof(s_name)) &&
 844                             strncasecmp(filename, l_name, sizeof(l_name))) {
 845                                 debug("Mismatch: |%s|%s|\n",
 846                                         s_name, l_name);
 847                                 dentptr++;
 848                                 if (is_next_clust(mydata, dentptr))
 849                                         break;
 850                                 continue;
 851                         }
 852
 853                         memcpy(retdent, dentptr, sizeof(dir_entry));
 854
 855                         debug("DentName: %s", s_name);
 856                         debug(", start: 0x%x", START(dentptr));
 857                         debug(", size:  0x%x %s\n",
 858                               FAT2CPU32(dentptr->size),
 859                               (dentptr->attr & ATTR_DIR) ?
 860                               "(DIR)" : "");
 861
 862                         return dentptr;
 863                 }
 864
 865                 /*
 866                  * In FAT16/12, the root dir is locate before data area, shows
 867                  * in following:
 868                  * -------------------------------------------------------------
 869                  * | Boot | FAT1 & 2 | Root dir | Data (start from cluster #2) |
 870                  * -------------------------------------------------------------
 871                  *
 872                  * As a result if curclust is in Root dir, it is a negative
 873                  * number or 0, 1.
 874                  *
 875                  */
 876                 if (mydata->fatsize != 32 && (int)curclust <= 1) {
 877                         /* Current clust is in root dir, set to next clust */
 878                         curclust++;
 879                         if ((int)curclust <= 1)
 880                                 continue;       /* continue to find */
 881
 882                         /* Reach the end of root dir */
 883                         empty_dentptr = dentptr;
 884                         return NULL;
 885                 }
 886
 887                 curclust = get_fatent(mydata, dir_curclust);
 888                 if (IS_LAST_CLUST(curclust, mydata->fatsize)) {
 889                         empty_dentptr = dentptr;
 890                         return NULL;
 891                 }
 892                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 893                         debug("curclust: 0x%x\n", curclust);
 894                         debug("Invalid FAT entry\n");
 895                         return NULL;
 896                 }
 897         }
 898
 899         return NULL;
 900 }
 901
 902 static int do_fat_write(const char *filename, void *buffer, loff_t size,
 903                         loff_t *actwrite)
 904 {
 905         dir_entry *dentptr, *retdent;
 906         __u32 startsect;
 907         __u32 start_cluster;
 908         boot_sector bs;
 909         volume_info volinfo;
 910         fsdata datablock;
 911         fsdata *mydata = &datablock;
 912         int cursect, i;
 913         int ret = -1, name_len;
 914         char l_filename[VFAT_MAXLEN_BYTES];
 915         char bad[2] = " ";
 916         const char illegal[] = "<>:\"/\\|?*";
 917
 918         *actwrite = size;
 919         dir_curclust = 0;
 920
 921         if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
 922                 debug("error: reading boot sector\n");
 923                 return -1;
 924         }
 925
 926         total_sector = bs.total_sect;
 927         if (total_sector == 0)
 928                 total_sector = (int)cur_part_info.size; /* cast of lbaint_t */
 929
 930         if (mydata->fatsize == 32)
 931                 mydata->fatlength = bs.fat32_length;
 932         else
 933                 mydata->fatlength = bs.fat_length;
 934
 935         mydata->fat_sect = bs.reserved;
 936
 937         cursect = mydata->rootdir_sect
 938                 = mydata->fat_sect + mydata->fatlength * bs.fats;
 939         num_of_fats = bs.fats;
 940
 941         mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
 942         mydata->clust_size = bs.cluster_size;
 943
 944         if (mydata->fatsize == 32) {
 945                 mydata->data_begin = mydata->rootdir_sect -
 946                                         (mydata->clust_size * 2);
 947         } else {
 948                 int rootdir_size;
 949
 950                 rootdir_size = ((bs.dir_entries[1]  * (int)256 +
 951                                  bs.dir_entries[0]) *
 952                                  sizeof(dir_entry)) /
 953                                  mydata->sect_size;
 954                 mydata->data_begin = mydata->rootdir_sect +
 955                                         rootdir_size -
 956                                         (mydata->clust_size * 2);
 957         }
 958
 959         mydata->fatbufnum = -1;
 960         mydata->fat_dirty = 0;
 961         mydata->fatbuf = memalign(ARCH_DMA_MINALIGN, FATBUFSIZE);
 962         if (mydata->fatbuf == NULL) {
 963                 debug("Error: allocating memory\n");
 964                 return -1;
 965         }
 966
 967         if (disk_read(cursect,
 968                 (mydata->fatsize == 32) ?
 969                 (mydata->clust_size) :
 970                 PREFETCH_BLOCKS, do_fat_read_at_block) < 0) {
 971                 debug("Error: reading rootdir block\n");
 972                 goto exit;
 973         }
 974         dentptr = (dir_entry *) do_fat_read_at_block;
 975
 976         /* Strip leading (back-)slashes */
 977         while ISDIRDELIM(*filename)
 978                 ++filename;
 979         /* Check that the filename is valid */
 980         for (i = 0; i < strlen(illegal); ++i) {
 981                 *bad = illegal[i];
 982                 if (strstr(filename, bad)) {
 983                         printf("FAT: illegal filename (%s)\n", filename);
 984                         return -1;
 985                 }
 986         }
 987
 988         name_len = strlen(filename);
 989         if (name_len >= VFAT_MAXLEN_BYTES)
 990                 name_len = VFAT_MAXLEN_BYTES - 1;
 991
 992         memcpy(l_filename, filename, name_len);
 993         l_filename[name_len] = 0; /* terminate the string */
 994         downcase(l_filename, INT_MAX);
 995
 996         startsect = mydata->rootdir_sect;
 997         retdent = find_directory_entry(mydata, startsect,
 998                                 l_filename, dentptr, 0);
 999         if (retdent) {
1000                 /* Update file size and start_cluster in a directory entry */
1001                 retdent->size = cpu_to_le32(size);
1002                 start_cluster = START(retdent);
1003
1004                 if (start_cluster) {
1005                         if (size) {
1006                                 ret = check_overflow(mydata, start_cluster,
1007                                                         size);
1008                                 if (ret) {
1009                                         printf("Error: %llu overflow\n", size);
1010                                         goto exit;
1011                                 }
1012                         }
1013
1014                         ret = clear_fatent(mydata, start_cluster);
1015                         if (ret) {
1016                                 printf("Error: clearing FAT entries\n");
1017                                 goto exit;
1018                         }
1019
1020                         if (!size)
1021                                 set_start_cluster(mydata, retdent, 0);
1022                 } else if (size) {
1023                         ret = start_cluster = find_empty_cluster(mydata);
1024                         if (ret < 0) {
1025                                 printf("Error: finding empty cluster\n");
1026                                 goto exit;
1027                         }
1028
1029                         ret = check_overflow(mydata, start_cluster, size);
1030                         if (ret) {
1031                                 printf("Error: %llu overflow\n", size);
1032                                 goto exit;
1033                         }
1034
1035                         set_start_cluster(mydata, retdent, start_cluster);
1036                 }
1037         } else {
1038                 /* Set short name to set alias checksum field in dir_slot */
1039                 set_name(empty_dentptr, filename);
1040                 fill_dir_slot(mydata, &empty_dentptr, filename);
1041
1042                 if (size) {
1043                         ret = start_cluster = find_empty_cluster(mydata);
1044                         if (ret < 0) {
1045                                 printf("Error: finding empty cluster\n");
1046                                 goto exit;
1047                         }
1048
1049                         ret = check_overflow(mydata, start_cluster, size);
1050                         if (ret) {
1051                                 printf("Error: %llu overflow\n", size);
1052                                 goto exit;
1053                         }
1054                 } else {
1055                         start_cluster = 0;
1056                 }
1057
1058                 /* Set attribute as archieve for regular file */
1059                 fill_dentry(mydata, empty_dentptr, filename,
1060                         start_cluster, size, 0x20);
1061
1062                 retdent = empty_dentptr;
1063         }
1064
1065         ret = set_contents(mydata, retdent, buffer, size, actwrite);
1066         if (ret < 0) {
1067                 printf("Error: writing contents\n");
1068                 goto exit;
1069         }
1070         debug("attempt to write 0x%llx bytes\n", *actwrite);
1071
1072         /* Flush fat buffer */
1073         ret = flush_dirty_fat_buffer(mydata);
1074         if (ret) {
1075                 printf("Error: flush fat buffer\n");
1076                 goto exit;
1077         }
1078
1079         /* Write directory table to device */
1080         ret = set_cluster(mydata, dir_curclust, get_dentfromdir_block,
1081                         mydata->clust_size * mydata->sect_size);
1082         if (ret)
1083                 printf("Error: writing directory entry\n");
1084
1085 exit:
1086         free(mydata->fatbuf);
1087         return ret;
1088 }
1089
1090 int file_fat_write(const char *filename, void *buffer, loff_t offset,
1091                    loff_t maxsize, loff_t *actwrite)
1092 {
1093         if (offset != 0) {
1094                 printf("Error: non zero offset is currently not supported.\n");
1095                 return -1;
1096         }
1097
1098         printf("writing %s\n", filename);
1099         return do_fat_write(filename, buffer, maxsize, actwrite);
1100 }