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  * See file CREDITS for list of people who contributed to this
   7  * project.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation; either version 2 of
  12  * the License, or (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program; if not, write to the Free Software
  21  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  22  * MA 02111-1307 USA
  23  */
  24
  25 #include <common.h>
  26 #include <command.h>
  27 #include <config.h>
  28 #include <fat.h>
  29 #include <asm/byteorder.h>
  30 #include <part.h>
  31 #include "fat.c"
  32
  33 static void uppercase(char *str, int len)
  34 {
  35         int i;
  36
  37         for (i = 0; i < len; i++) {
  38                 TOUPPER(*str);
  39                 str++;
  40         }
  41 }
  42
  43 static int total_sector;
  44 static int disk_write(__u32 startblock, __u32 getsize, __u8 *bufptr)
  45 {
  46         if (cur_dev == NULL)
  47                 return -1;
  48
  49         if (startblock + getsize > total_sector) {
  50                 printf("error: overflow occurs\n");
  51                 return -1;
  52         }
  53
  54         startblock += part_offset;
  55
  56         if (cur_dev->block_read) {
  57                 return cur_dev->block_write(cur_dev->dev, startblock, getsize,
  58                                            (unsigned long *) bufptr);
  59         }
  60         return -1;
  61 }
  62
  63 /*
  64  * Set short name in directory entry
  65  */
  66 static void set_name(dir_entry *dirent, const char *filename)
  67 {
  68         char s_name[VFAT_MAXLEN_BYTES];
  69         char *period;
  70         int period_location, len, i, ext_num;
  71
  72         if (filename == NULL)
  73                 return;
  74
  75         len = strlen(filename);
  76         if (len == 0)
  77                 return;
  78
  79         memcpy(s_name, filename, len);
  80         uppercase(s_name, len);
  81
  82         period = strchr(s_name, '.');
  83         if (period == NULL) {
  84                 period_location = len;
  85                 ext_num = 0;
  86         } else {
  87                 period_location = period - s_name;
  88                 ext_num = len - period_location - 1;
  89         }
  90
  91         /* Pad spaces when the length of file name is shorter than eight */
  92         if (period_location < 8) {
  93                 memcpy(dirent->name, s_name, period_location);
  94                 for (i = period_location; i < 8; i++)
  95                         dirent->name[i] = ' ';
  96         } else if (period_location == 8) {
  97                 memcpy(dirent->name, s_name, period_location);
  98         } else {
  99                 memcpy(dirent->name, s_name, 6);
 100                 dirent->name[6] = '~';
 101                 dirent->name[7] = '1';
 102         }
 103
 104         if (ext_num < 3) {
 105                 memcpy(dirent->ext, s_name + period_location + 1, ext_num);
 106                 for (i = ext_num; i < 3; i++)
 107                         dirent->ext[i] = ' ';
 108         } else
 109                 memcpy(dirent->ext, s_name + period_location + 1, 3);
 110
 111         debug("name : %s\n", dirent->name);
 112         debug("ext : %s\n", dirent->ext);
 113 }
 114
 115 /*
 116  * Write fat buffer into block device
 117  */
 118 static int flush_fat_buffer(fsdata *mydata)
 119 {
 120         int getsize = FATBUFBLOCKS;
 121         __u32 fatlength = mydata->fatlength;
 122         __u8 *bufptr = mydata->fatbuf;
 123         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 124
 125         fatlength *= mydata->sect_size;
 126         startblock += mydata->fat_sect;
 127
 128         if (getsize > fatlength)
 129                 getsize = fatlength;
 130
 131         /* Write FAT buf */
 132         if (disk_write(startblock, getsize, bufptr) < 0) {
 133                 debug("error: writing FAT blocks\n");
 134                 return -1;
 135         }
 136
 137         return 0;
 138 }
 139
 140 /*
 141  * Get the entry at index 'entry' in a FAT (12/16/32) table.
 142  * On failure 0x00 is returned.
 143  * When bufnum is changed, write back the previous fatbuf to the disk.
 144  */
 145 static __u32 get_fatent_value(fsdata *mydata, __u32 entry)
 146 {
 147         __u32 bufnum;
 148         __u32 off16, offset;
 149         __u32 ret = 0x00;
 150         __u16 val1, val2;
 151
 152         switch (mydata->fatsize) {
 153         case 32:
 154                 bufnum = entry / FAT32BUFSIZE;
 155                 offset = entry - bufnum * FAT32BUFSIZE;
 156                 break;
 157         case 16:
 158                 bufnum = entry / FAT16BUFSIZE;
 159                 offset = entry - bufnum * FAT16BUFSIZE;
 160                 break;
 161         case 12:
 162                 bufnum = entry / FAT12BUFSIZE;
 163                 offset = entry - bufnum * FAT12BUFSIZE;
 164                 break;
 165
 166         default:
 167                 /* Unsupported FAT size */
 168                 return ret;
 169         }
 170
 171         debug("FAT%d: entry: 0x%04x = %d, offset: 0x%04x = %d\n",
 172                mydata->fatsize, entry, entry, offset, offset);
 173
 174         /* Read a new block of FAT entries into the cache. */
 175         if (bufnum != mydata->fatbufnum) {
 176                 int getsize = FATBUFBLOCKS;
 177                 __u8 *bufptr = mydata->fatbuf;
 178                 __u32 fatlength = mydata->fatlength;
 179                 __u32 startblock = bufnum * FATBUFBLOCKS;
 180
 181                 if (getsize > fatlength)
 182                         getsize = fatlength;
 183
 184                 fatlength *= mydata->sect_size; /* We want it in bytes now */
 185                 startblock += mydata->fat_sect; /* Offset from start of disk */
 186
 187                 /* Write back the fatbuf to the disk */
 188                 if (mydata->fatbufnum != -1) {
 189                         if (flush_fat_buffer(mydata) < 0)
 190                                 return -1;
 191                 }
 192
 193                 if (disk_read(startblock, getsize, bufptr) < 0) {
 194                         debug("Error reading FAT blocks\n");
 195                         return ret;
 196                 }
 197                 mydata->fatbufnum = bufnum;
 198         }
 199
 200         /* Get the actual entry from the table */
 201         switch (mydata->fatsize) {
 202         case 32:
 203                 ret = FAT2CPU32(((__u32 *) mydata->fatbuf)[offset]);
 204                 break;
 205         case 16:
 206                 ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[offset]);
 207                 break;
 208         case 12:
 209                 off16 = (offset * 3) / 4;
 210
 211                 switch (offset & 0x3) {
 212                 case 0:
 213                         ret = FAT2CPU16(((__u16 *) mydata->fatbuf)[off16]);
 214                         ret &= 0xfff;
 215                         break;
 216                 case 1:
 217                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 218                         val1 &= 0xf000;
 219                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 220                         val2 &= 0x00ff;
 221                         ret = (val2 << 4) | (val1 >> 12);
 222                         break;
 223                 case 2:
 224                         val1 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 225                         val1 &= 0xff00;
 226                         val2 = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16 + 1]);
 227                         val2 &= 0x000f;
 228                         ret = (val2 << 8) | (val1 >> 8);
 229                         break;
 230                 case 3:
 231                         ret = FAT2CPU16(((__u16 *)mydata->fatbuf)[off16]);
 232                         ret = (ret & 0xfff0) >> 4;
 233                         break;
 234                 default:
 235                         break;
 236                 }
 237                 break;
 238         }
 239         debug("FAT%d: ret: %08x, entry: %08x, offset: %04x\n",
 240                mydata->fatsize, ret, entry, offset);
 241
 242         return ret;
 243 }
 244
 245 #ifdef CONFIG_SUPPORT_VFAT
 246 /*
 247  * Set the file name information from 'name' into 'slotptr',
 248  */
 249 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 250 {
 251         int j, end_idx = 0;
 252
 253         for (j = 0; j <= 8; j += 2) {
 254                 if (name[*idx] == 0x00) {
 255                         slotptr->name0_4[j] = 0;
 256                         slotptr->name0_4[j + 1] = 0;
 257                         end_idx++;
 258                         goto name0_4;
 259                 }
 260                 slotptr->name0_4[j] = name[*idx];
 261                 (*idx)++;
 262                 end_idx++;
 263         }
 264         for (j = 0; j <= 10; j += 2) {
 265                 if (name[*idx] == 0x00) {
 266                         slotptr->name5_10[j] = 0;
 267                         slotptr->name5_10[j + 1] = 0;
 268                         end_idx++;
 269                         goto name5_10;
 270                 }
 271                 slotptr->name5_10[j] = name[*idx];
 272                 (*idx)++;
 273                 end_idx++;
 274         }
 275         for (j = 0; j <= 2; j += 2) {
 276                 if (name[*idx] == 0x00) {
 277                         slotptr->name11_12[j] = 0;
 278                         slotptr->name11_12[j + 1] = 0;
 279                         end_idx++;
 280                         goto name11_12;
 281                 }
 282                 slotptr->name11_12[j] = name[*idx];
 283                 (*idx)++;
 284                 end_idx++;
 285         }
 286
 287         if (name[*idx] == 0x00)
 288                 return 1;
 289
 290         return 0;
 291 /* Not used characters are filled with 0xff 0xff */
 292 name0_4:
 293         for (; end_idx < 5; end_idx++) {
 294                 slotptr->name0_4[end_idx * 2] = 0xff;
 295                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 296         }
 297         end_idx = 5;
 298 name5_10:
 299         end_idx -= 5;
 300         for (; end_idx < 6; end_idx++) {
 301                 slotptr->name5_10[end_idx * 2] = 0xff;
 302                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 303         }
 304         end_idx = 11;
 305 name11_12:
 306         end_idx -= 11;
 307         for (; end_idx < 2; end_idx++) {
 308                 slotptr->name11_12[end_idx * 2] = 0xff;
 309                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 310         }
 311
 312         return 1;
 313 }
 314
 315 static int is_next_clust(fsdata *mydata, dir_entry *dentptr);
 316 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr);
 317
 318 /*
 319  * Fill dir_slot entries with appropriate name, id, and attr
 320  * The real directory entry is returned by 'dentptr'
 321  */
 322 static void
 323 fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name)
 324 {
 325         dir_slot *slotptr = (dir_slot *)get_vfatname_block;
 326         __u8 counter = 0, checksum;
 327         int idx = 0, ret;
 328         char s_name[16];
 329
 330         /* Get short file name and checksum value */
 331         strncpy(s_name, (*dentptr)->name, 16);
 332         checksum = mkcksum(s_name);
 333
 334         do {
 335                 memset(slotptr, 0x00, sizeof(dir_slot));
 336                 ret = str2slot(slotptr, l_name, &idx);
 337                 slotptr->id = ++counter;
 338                 slotptr->attr = ATTR_VFAT;
 339                 slotptr->alias_checksum = checksum;
 340                 slotptr++;
 341         } while (ret == 0);
 342
 343         slotptr--;
 344         slotptr->id |= LAST_LONG_ENTRY_MASK;
 345
 346         while (counter >= 1) {
 347                 if (is_next_clust(mydata, *dentptr)) {
 348                         /* A new cluster is allocated for directory table */
 349                         flush_dir_table(mydata, dentptr);
 350                 }
 351                 memcpy(*dentptr, slotptr, sizeof(dir_slot));
 352                 (*dentptr)++;
 353                 slotptr--;
 354                 counter--;
 355         }
 356
 357         if (is_next_clust(mydata, *dentptr)) {
 358                 /* A new cluster is allocated for directory table */
 359                 flush_dir_table(mydata, dentptr);
 360         }
 361 }
 362
 363 static __u32 dir_curclust;
 364
 365 /*
 366  * Extract the full long filename starting at 'retdent' (which is really
 367  * a slot) into 'l_name'. If successful also copy the real directory entry
 368  * into 'retdent'
 369  * If additional adjacent cluster for directory entries is read into memory,
 370  * then 'get_vfatname_block' is copied into 'get_dentfromdir_block' and
 371  * the location of the real directory entry is returned by 'retdent'
 372  * Return 0 on success, -1 otherwise.
 373  */
 374 static int
 375 get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster,
 376               dir_entry **retdent, char *l_name)
 377 {
 378         dir_entry *realdent;
 379         dir_slot *slotptr = (dir_slot *)(*retdent);
 380         dir_slot *slotptr2 = NULL;
 381         __u8 *buflimit = cluster + mydata->sect_size * ((curclust == 0) ?
 382                                                         PREFETCH_BLOCKS :
 383                                                         mydata->clust_size);
 384         __u8 counter = (slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff;
 385         int idx = 0, cur_position = 0;
 386
 387         if (counter > VFAT_MAXSEQ) {
 388                 debug("Error: VFAT name is too long\n");
 389                 return -1;
 390         }
 391
 392         while ((__u8 *)slotptr < buflimit) {
 393                 if (counter == 0)
 394                         break;
 395                 if (((slotptr->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter)
 396                         return -1;
 397                 slotptr++;
 398                 counter--;
 399         }
 400
 401         if ((__u8 *)slotptr >= buflimit) {
 402                 if (curclust == 0)
 403                         return -1;
 404                 curclust = get_fatent_value(mydata, dir_curclust);
 405                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 406                         debug("curclust: 0x%x\n", curclust);
 407                         printf("Invalid FAT entry\n");
 408                         return -1;
 409                 }
 410
 411                 dir_curclust = curclust;
 412
 413                 if (get_cluster(mydata, curclust, get_vfatname_block,
 414                                 mydata->clust_size * mydata->sect_size) != 0) {
 415                         debug("Error: reading directory block\n");
 416                         return -1;
 417                 }
 418
 419                 slotptr2 = (dir_slot *)get_vfatname_block;
 420                 while (counter > 0) {
 421                         if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK)
 422                             & 0xff) != counter)
 423                                 return -1;
 424                         slotptr2++;
 425                         counter--;
 426                 }
 427
 428                 /* Save the real directory entry */
 429                 realdent = (dir_entry *)slotptr2;
 430                 while ((__u8 *)slotptr2 > get_vfatname_block) {
 431                         slotptr2--;
 432                         slot2str(slotptr2, l_name, &idx);
 433                 }
 434         } else {
 435                 /* Save the real directory entry */
 436                 realdent = (dir_entry *)slotptr;
 437         }
 438
 439         do {
 440                 slotptr--;
 441                 if (slot2str(slotptr, l_name, &idx))
 442                         break;
 443         } while (!(slotptr->id & LAST_LONG_ENTRY_MASK));
 444
 445         l_name[idx] = '\0';
 446         if (*l_name == DELETED_FLAG)
 447                 *l_name = '\0';
 448         else if (*l_name == aRING)
 449                 *l_name = DELETED_FLAG;
 450         downcase(l_name);
 451
 452         /* Return the real directory entry */
 453         *retdent = realdent;
 454
 455         if (slotptr2) {
 456                 memcpy(get_dentfromdir_block, get_vfatname_block,
 457                         mydata->clust_size * mydata->sect_size);
 458                 cur_position = (__u8 *)realdent - get_vfatname_block;
 459                 *retdent = (dir_entry *) &get_dentfromdir_block[cur_position];
 460         }
 461
 462         return 0;
 463 }
 464
 465 #endif
 466
 467 /*
 468  * Set the entry at index 'entry' in a FAT (16/32) table.
 469  */
 470 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 471 {
 472         __u32 bufnum, offset;
 473
 474         switch (mydata->fatsize) {
 475         case 32:
 476                 bufnum = entry / FAT32BUFSIZE;
 477                 offset = entry - bufnum * FAT32BUFSIZE;
 478                 break;
 479         case 16:
 480                 bufnum = entry / FAT16BUFSIZE;
 481                 offset = entry - bufnum * FAT16BUFSIZE;
 482                 break;
 483         default:
 484                 /* Unsupported FAT size */
 485                 return -1;
 486         }
 487
 488         /* Read a new block of FAT entries into the cache. */
 489         if (bufnum != mydata->fatbufnum) {
 490                 int getsize = FATBUFBLOCKS;
 491                 __u8 *bufptr = mydata->fatbuf;
 492                 __u32 fatlength = mydata->fatlength;
 493                 __u32 startblock = bufnum * FATBUFBLOCKS;
 494
 495                 fatlength *= mydata->sect_size;
 496                 startblock += mydata->fat_sect;
 497
 498                 if (getsize > fatlength)
 499                         getsize = fatlength;
 500
 501                 if (mydata->fatbufnum != -1) {
 502                         if (flush_fat_buffer(mydata) < 0)
 503                                 return -1;
 504                 }
 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         /* Set the actual entry */
 514         switch (mydata->fatsize) {
 515         case 32:
 516                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 517                 break;
 518         case 16:
 519                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 520                 break;
 521         default:
 522                 return -1;
 523         }
 524
 525         return 0;
 526 }
 527
 528 /*
 529  * Determine the entry value at index 'entry' in a FAT (16/32) table
 530  */
 531 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 532 {
 533         __u32 next_fat, next_entry = entry + 1;
 534
 535         while (1) {
 536                 next_fat = get_fatent_value(mydata, next_entry);
 537                 if (next_fat == 0) {
 538                         set_fatent_value(mydata, entry, next_entry);
 539                         break;
 540                 }
 541                 next_entry++;
 542         }
 543         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 544                mydata->fatsize, entry, next_entry);
 545
 546         return next_entry;
 547 }
 548
 549 /*
 550  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 551  * Return 0 on success, -1 otherwise.
 552  */
 553 static int
 554 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 555              unsigned long size)
 556 {
 557         int idx = 0;
 558         __u32 startsect;
 559
 560         if (clustnum > 0)
 561                 startsect = mydata->data_begin +
 562                                 clustnum * mydata->clust_size;
 563         else
 564                 startsect = mydata->rootdir_sect;
 565
 566         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 567
 568         if (disk_write(startsect, size / mydata->sect_size, buffer) < 0) {
 569                 debug("Error writing data\n");
 570                 return -1;
 571         }
 572
 573         if (size % mydata->sect_size) {
 574                 __u8 tmpbuf[mydata->sect_size];
 575
 576                 idx = size / mydata->sect_size;
 577                 buffer += idx * mydata->sect_size;
 578                 memcpy(tmpbuf, buffer, size % mydata->sect_size);
 579
 580                 if (disk_write(startsect + idx, 1, tmpbuf) < 0) {
 581                         debug("Error writing data\n");
 582                         return -1;
 583                 }
 584
 585                 return 0;
 586         }
 587
 588         return 0;
 589 }
 590
 591 /*
 592  * Find the first empty cluster
 593  */
 594 static int find_empty_cluster(fsdata *mydata)
 595 {
 596         __u32 fat_val, entry = 3;
 597
 598         while (1) {
 599                 fat_val = get_fatent_value(mydata, entry);
 600                 if (fat_val == 0)
 601                         break;
 602                 entry++;
 603         }
 604
 605         return entry;
 606 }
 607
 608 /*
 609  * Write directory entries in 'get_dentfromdir_block' to block device
 610  */
 611 static void flush_dir_table(fsdata *mydata, dir_entry **dentptr)
 612 {
 613         int dir_newclust = 0;
 614
 615         if (set_cluster(mydata, dir_curclust,
 616                     get_dentfromdir_block,
 617                     mydata->clust_size * mydata->sect_size) != 0) {
 618                 printf("error: wrinting directory entry\n");
 619                 return;
 620         }
 621         dir_newclust = find_empty_cluster(mydata);
 622         set_fatent_value(mydata, dir_curclust, dir_newclust);
 623         if (mydata->fatsize == 32)
 624                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 625         else if (mydata->fatsize == 16)
 626                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 627
 628         dir_curclust = dir_newclust;
 629
 630         if (flush_fat_buffer(mydata) < 0)
 631                 return;
 632
 633         memset(get_dentfromdir_block, 0x00,
 634                 mydata->clust_size * mydata->sect_size);
 635
 636         *dentptr = (dir_entry *) get_dentfromdir_block;
 637 }
 638
 639 /*
 640  * Set empty cluster from 'entry' to the end of a file
 641  */
 642 static int clear_fatent(fsdata *mydata, __u32 entry)
 643 {
 644         __u32 fat_val;
 645
 646         while (1) {
 647                 fat_val = get_fatent_value(mydata, entry);
 648                 if (fat_val != 0)
 649                         set_fatent_value(mydata, entry, 0);
 650                 else
 651                         break;
 652
 653                 if (fat_val == 0xfffffff || fat_val == 0xffff)
 654                         break;
 655
 656                 entry = fat_val;
 657         }
 658
 659         /* Flush fat buffer */
 660         if (flush_fat_buffer(mydata) < 0)
 661                 return -1;
 662
 663         return 0;
 664 }
 665
 666 /*
 667  * Write at most 'maxsize' bytes from 'buffer' into
 668  * the file associated with 'dentptr'
 669  * Return the number of bytes read or -1 on fatal errors.
 670  */
 671 static int
 672 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 673               unsigned long maxsize)
 674 {
 675         unsigned long filesize = FAT2CPU32(dentptr->size), gotsize = 0;
 676         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 677         __u32 curclust = START(dentptr);
 678         __u32 endclust = 0, newclust = 0;
 679         unsigned long actsize;
 680
 681         debug("Filesize: %ld bytes\n", filesize);
 682
 683         if (maxsize > 0 && filesize > maxsize)
 684                 filesize = maxsize;
 685
 686         debug("%ld bytes\n", filesize);
 687
 688         actsize = bytesperclust;
 689         endclust = curclust;
 690         do {
 691                 /* search for consecutive clusters */
 692                 while (actsize < filesize) {
 693                         newclust = determine_fatent(mydata, endclust);
 694
 695                         if ((newclust - 1) != endclust)
 696                                 goto getit;
 697
 698                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 699                                 debug("curclust: 0x%x\n", newclust);
 700                                 debug("Invalid FAT entry\n");
 701                                 return gotsize;
 702                         }
 703                         endclust = newclust;
 704                         actsize += bytesperclust;
 705                 }
 706                 /* actsize >= file size */
 707                 actsize -= bytesperclust;
 708                 /* set remaining clusters */
 709                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 710                         debug("error: writing cluster\n");
 711                         return -1;
 712                 }
 713
 714                 /* set remaining bytes */
 715                 gotsize += (int)actsize;
 716                 filesize -= actsize;
 717                 buffer += actsize;
 718                 actsize = filesize;
 719
 720                 if (set_cluster(mydata, endclust, buffer, (int)actsize) != 0) {
 721                         debug("error: writing cluster\n");
 722                         return -1;
 723                 }
 724                 gotsize += actsize;
 725
 726                 /* Mark end of file in FAT */
 727                 if (mydata->fatsize == 16)
 728                         newclust = 0xffff;
 729                 else if (mydata->fatsize == 32)
 730                         newclust = 0xfffffff;
 731                 set_fatent_value(mydata, endclust, newclust);
 732
 733                 return gotsize;
 734 getit:
 735                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 736                         debug("error: writing cluster\n");
 737                         return -1;
 738                 }
 739                 gotsize += (int)actsize;
 740                 filesize -= actsize;
 741                 buffer += actsize;
 742
 743                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 744                         debug("curclust: 0x%x\n", curclust);
 745                         debug("Invalid FAT entry\n");
 746                         return gotsize;
 747                 }
 748                 actsize = bytesperclust;
 749                 curclust = endclust = newclust;
 750         } while (1);
 751 }
 752
 753 /*
 754  * Fill dir_entry
 755  */
 756 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 757         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 758 {
 759         if (mydata->fatsize == 32)
 760                 dentptr->starthi =
 761                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 762         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 763         dentptr->size = cpu_to_le32(size);
 764
 765         dentptr->attr = attr;
 766
 767         set_name(dentptr, filename);
 768 }
 769
 770 /*
 771  * Check whether adding a file makes the file system to
 772  * exceed the size of the block device
 773  * Return -1 when overflow occurs, otherwise return 0
 774  */
 775 static int check_overflow(fsdata *mydata, __u32 clustnum, unsigned long size)
 776 {
 777         __u32 startsect, sect_num;
 778
 779         if (clustnum > 0) {
 780                 startsect = mydata->data_begin +
 781                                 clustnum * mydata->clust_size;
 782         } else {
 783                 startsect = mydata->rootdir_sect;
 784         }
 785
 786         sect_num = size / mydata->sect_size;
 787         if (size % mydata->sect_size)
 788                 sect_num++;
 789
 790         if (startsect + sect_num > total_sector)
 791                 return -1;
 792
 793         return 0;
 794 }
 795
 796 /*
 797  * Check if adding several entries exceed one cluster boundary
 798  */
 799 static int is_next_clust(fsdata *mydata, dir_entry *dentptr)
 800 {
 801         int cur_position;
 802
 803         cur_position = (__u8 *)dentptr - get_dentfromdir_block;
 804
 805         if (cur_position >= mydata->clust_size * mydata->sect_size)
 806                 return 1;
 807         else
 808                 return 0;
 809 }
 810
 811 static dir_entry *empty_dentptr;
 812 /*
 813  * Find a directory entry based on filename or start cluster number
 814  * If the directory entry is not found,
 815  * the new position for writing a directory entry will be returned
 816  */
 817 static dir_entry *find_directory_entry(fsdata *mydata, int startsect,
 818         char *filename, dir_entry *retdent, __u32 start)
 819 {
 820         __u16 prevcksum = 0xffff;
 821         __u32 curclust = (startsect - mydata->data_begin) / mydata->clust_size;
 822
 823         debug("get_dentfromdir: %s\n", filename);
 824
 825         while (1) {
 826                 dir_entry *dentptr;
 827
 828                 int i;
 829
 830                 if (get_cluster(mydata, curclust, get_dentfromdir_block,
 831                             mydata->clust_size * mydata->sect_size) != 0) {
 832                         printf("Error: reading directory block\n");
 833                         return NULL;
 834                 }
 835
 836                 dentptr = (dir_entry *)get_dentfromdir_block;
 837
 838                 dir_curclust = curclust;
 839
 840                 for (i = 0; i < DIRENTSPERCLUST; i++) {
 841                         char s_name[14], l_name[VFAT_MAXLEN_BYTES];
 842
 843                         l_name[0] = '\0';
 844                         if (dentptr->name[0] == DELETED_FLAG) {
 845                                 dentptr++;
 846                                 if (is_next_clust(mydata, dentptr))
 847                                         break;
 848                                 continue;
 849                         }
 850                         if ((dentptr->attr & ATTR_VOLUME)) {
 851 #ifdef CONFIG_SUPPORT_VFAT
 852                                 if ((dentptr->attr & ATTR_VFAT) &&
 853                                     (dentptr->name[0] & LAST_LONG_ENTRY_MASK)) {
 854                                         prevcksum =
 855                                         ((dir_slot *)dentptr)->alias_checksum;
 856                                         get_long_file_name(mydata, curclust,
 857                                                      get_dentfromdir_block,
 858                                                      &dentptr, l_name);
 859                                         debug("vfatname: |%s|\n", l_name);
 860                                 } else
 861 #endif
 862                                 {
 863                                         /* Volume label or VFAT entry */
 864                                         dentptr++;
 865                                         if (is_next_clust(mydata, dentptr))
 866                                                 break;
 867                                         continue;
 868                                 }
 869                         }
 870                         if (dentptr->name[0] == 0) {
 871                                 debug("Dentname == NULL - %d\n", i);
 872                                 empty_dentptr = dentptr;
 873                                 return NULL;
 874                         }
 875
 876                         get_name(dentptr, s_name);
 877
 878                         if (strcmp(filename, s_name)
 879                             && strcmp(filename, l_name)) {
 880                                 debug("Mismatch: |%s|%s|\n",
 881                                         s_name, l_name);
 882                                 dentptr++;
 883                                 if (is_next_clust(mydata, dentptr))
 884                                         break;
 885                                 continue;
 886                         }
 887
 888                         memcpy(retdent, dentptr, sizeof(dir_entry));
 889
 890                         debug("DentName: %s", s_name);
 891                         debug(", start: 0x%x", START(dentptr));
 892                         debug(", size:  0x%x %s\n",
 893                               FAT2CPU32(dentptr->size),
 894                               (dentptr->attr & ATTR_DIR) ?
 895                               "(DIR)" : "");
 896
 897                         return dentptr;
 898                 }
 899
 900                 curclust = get_fatent_value(mydata, dir_curclust);
 901                 if ((curclust >= 0xffffff8) || (curclust >= 0xfff8)) {
 902                         empty_dentptr = dentptr;
 903                         return NULL;
 904                 }
 905                 if (CHECK_CLUST(curclust, mydata->fatsize)) {
 906                         debug("curclust: 0x%x\n", curclust);
 907                         debug("Invalid FAT entry\n");
 908                         return NULL;
 909                 }
 910         }
 911
 912         return NULL;
 913 }
 914
 915 static int do_fat_write(const char *filename, void *buffer,
 916         unsigned long size)
 917 {
 918         dir_entry *dentptr, *retdent;
 919         dir_slot *slotptr;
 920         __u32 startsect;
 921         __u32 start_cluster;
 922         boot_sector bs;
 923         volume_info volinfo;
 924         fsdata datablock;
 925         fsdata *mydata = &datablock;
 926         int cursect;
 927         int root_cluster, ret = -1, name_len;
 928         char l_filename[VFAT_MAXLEN_BYTES];
 929         int write_size = size;
 930
 931         dir_curclust = 0;
 932
 933         if (read_bootsectandvi(&bs, &volinfo, &mydata->fatsize)) {
 934                 debug("error: reading boot sector\n");
 935                 return -1;
 936         }
 937
 938         total_sector = bs.total_sect;
 939         if (total_sector == 0)
 940                 total_sector = part_size;
 941
 942         root_cluster = bs.root_cluster;
 943
 944         if (mydata->fatsize == 32)
 945                 mydata->fatlength = bs.fat32_length;
 946         else
 947                 mydata->fatlength = bs.fat_length;
 948
 949         mydata->fat_sect = bs.reserved;
 950
 951         cursect = mydata->rootdir_sect
 952                 = mydata->fat_sect + mydata->fatlength * bs.fats;
 953
 954         mydata->sect_size = (bs.sector_size[1] << 8) + bs.sector_size[0];
 955         mydata->clust_size = bs.cluster_size;
 956
 957         if (mydata->fatsize == 32) {
 958                 mydata->data_begin = mydata->rootdir_sect -
 959                                         (mydata->clust_size * 2);
 960         } else {
 961                 int rootdir_size;
 962
 963                 rootdir_size = ((bs.dir_entries[1]  * (int)256 +
 964                                  bs.dir_entries[0]) *
 965                                  sizeof(dir_entry)) /
 966                                  mydata->sect_size;
 967                 mydata->data_begin = mydata->rootdir_sect +
 968                                         rootdir_size -
 969                                         (mydata->clust_size * 2);
 970         }
 971
 972         mydata->fatbufnum = -1;
 973         mydata->fatbuf = malloc(FATBUFSIZE);
 974         if (mydata->fatbuf == NULL) {
 975                 debug("Error: allocating memory\n");
 976                 return -1;
 977         }
 978
 979         if (disk_read(cursect,
 980                 (mydata->fatsize == 32) ?
 981                 (mydata->clust_size) :
 982                 PREFETCH_BLOCKS, do_fat_read_block) < 0) {
 983                 debug("Error: reading rootdir block\n");
 984                 goto exit;
 985         }
 986         dentptr = (dir_entry *) do_fat_read_block;
 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);
 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 = FAT2CPU16(retdent->start);
1003                 if (mydata->fatsize == 32)
1004                         start_cluster |=
1005                                 (FAT2CPU16(retdent->starthi) << 16);
1006
1007                 ret = check_overflow(mydata, start_cluster, size);
1008                 if (ret) {
1009                         printf("Error: %ld overflow\n", size);
1010                         goto exit;
1011                 }
1012
1013                 ret = clear_fatent(mydata, start_cluster);
1014                 if (ret) {
1015                         printf("Error: clearing FAT entries\n");
1016                         goto exit;
1017                 }
1018
1019                 ret = set_contents(mydata, retdent, buffer, size);
1020                 if (ret < 0) {
1021                         printf("Error: writing contents\n");
1022                         goto exit;
1023                 }
1024                 write_size = ret;
1025                 debug("attempt to write 0x%x bytes\n", write_size);
1026
1027                 /* Flush fat buffer */
1028                 ret = flush_fat_buffer(mydata);
1029                 if (ret) {
1030                         printf("Error: flush fat buffer\n");
1031                         goto exit;
1032                 }
1033
1034                 /* Write directory table to device */
1035                 ret = set_cluster(mydata, dir_curclust,
1036                             get_dentfromdir_block,
1037                             mydata->clust_size * mydata->sect_size);
1038                 if (ret) {
1039                         printf("Error: writing directory entry\n");
1040                         goto exit;
1041                 }
1042         } else {
1043                 slotptr = (dir_slot *)empty_dentptr;
1044
1045                 /* Set short name to set alias checksum field in dir_slot */
1046                 set_name(empty_dentptr, filename);
1047                 fill_dir_slot(mydata, &empty_dentptr, filename);
1048
1049                 ret = start_cluster = find_empty_cluster(mydata);
1050                 if (ret < 0) {
1051                         printf("Error: finding empty cluster\n");
1052                         goto exit;
1053                 }
1054
1055                 ret = check_overflow(mydata, start_cluster, size);
1056                 if (ret) {
1057                         printf("Error: %ld overflow\n", size);
1058                         goto exit;
1059                 }
1060
1061                 /* Set attribute as archieve for regular file */
1062                 fill_dentry(mydata, empty_dentptr, filename,
1063                         start_cluster, size, 0x20);
1064
1065                 ret = set_contents(mydata, empty_dentptr, buffer, size);
1066                 if (ret < 0) {
1067                         printf("Error: writing contents\n");
1068                         goto exit;
1069                 }
1070                 write_size = ret;
1071                 debug("attempt to write 0x%x bytes\n", write_size);
1072
1073                 /* Flush fat buffer */
1074                 ret = flush_fat_buffer(mydata);
1075                 if (ret) {
1076                         printf("Error: flush fat buffer\n");
1077                         goto exit;
1078                 }
1079
1080                 /* Write directory table to device */
1081                 ret = set_cluster(mydata, dir_curclust,
1082                             get_dentfromdir_block,
1083                             mydata->clust_size * mydata->sect_size);
1084                 if (ret) {
1085                         printf("Error: writing directory entry\n");
1086                         goto exit;
1087                 }
1088         }
1089
1090 exit:
1091         free(mydata->fatbuf);
1092         return ret < 0 ? ret : write_size;
1093 }
1094
1095 int file_fat_write(const char *filename, void *buffer, unsigned long maxsize)
1096 {
1097         printf("writing %s\n", filename);
1098         return do_fat_write(filename, buffer, maxsize);
1099 }