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