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 /*
 103  * Write fat buffer into block device
 104  */
 105 static int flush_dirty_fat_buffer(fsdata *mydata)
 106 {
 107         int getsize = FATBUFBLOCKS;
 108         __u32 fatlength = mydata->fatlength;
 109         __u8 *bufptr = mydata->fatbuf;
 110         __u32 startblock = mydata->fatbufnum * FATBUFBLOCKS;
 111
 112         debug("debug: evicting %d, dirty: %d\n", mydata->fatbufnum,
 113               (int)mydata->fat_dirty);
 114
 115         if ((!mydata->fat_dirty) || (mydata->fatbufnum == -1))
 116                 return 0;
 117
 118         /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 119         if (startblock + getsize > fatlength)
 120                 getsize = fatlength - startblock;
 121
 122         startblock += mydata->fat_sect;
 123
 124         /* Write FAT buf */
 125         if (disk_write(startblock, getsize, bufptr) < 0) {
 126                 debug("error: writing FAT blocks\n");
 127                 return -1;
 128         }
 129
 130         if (mydata->fats == 2) {
 131                 /* Update corresponding second FAT blocks */
 132                 startblock += mydata->fatlength;
 133                 if (disk_write(startblock, getsize, bufptr) < 0) {
 134                         debug("error: writing second FAT blocks\n");
 135                         return -1;
 136                 }
 137         }
 138         mydata->fat_dirty = 0;
 139
 140         return 0;
 141 }
 142
 143 /*
 144  * Set the file name information from 'name' into 'slotptr',
 145  */
 146 static int str2slot(dir_slot *slotptr, const char *name, int *idx)
 147 {
 148         int j, end_idx = 0;
 149
 150         for (j = 0; j <= 8; j += 2) {
 151                 if (name[*idx] == 0x00) {
 152                         slotptr->name0_4[j] = 0;
 153                         slotptr->name0_4[j + 1] = 0;
 154                         end_idx++;
 155                         goto name0_4;
 156                 }
 157                 slotptr->name0_4[j] = name[*idx];
 158                 (*idx)++;
 159                 end_idx++;
 160         }
 161         for (j = 0; j <= 10; j += 2) {
 162                 if (name[*idx] == 0x00) {
 163                         slotptr->name5_10[j] = 0;
 164                         slotptr->name5_10[j + 1] = 0;
 165                         end_idx++;
 166                         goto name5_10;
 167                 }
 168                 slotptr->name5_10[j] = name[*idx];
 169                 (*idx)++;
 170                 end_idx++;
 171         }
 172         for (j = 0; j <= 2; j += 2) {
 173                 if (name[*idx] == 0x00) {
 174                         slotptr->name11_12[j] = 0;
 175                         slotptr->name11_12[j + 1] = 0;
 176                         end_idx++;
 177                         goto name11_12;
 178                 }
 179                 slotptr->name11_12[j] = name[*idx];
 180                 (*idx)++;
 181                 end_idx++;
 182         }
 183
 184         if (name[*idx] == 0x00)
 185                 return 1;
 186
 187         return 0;
 188 /* Not used characters are filled with 0xff 0xff */
 189 name0_4:
 190         for (; end_idx < 5; end_idx++) {
 191                 slotptr->name0_4[end_idx * 2] = 0xff;
 192                 slotptr->name0_4[end_idx * 2 + 1] = 0xff;
 193         }
 194         end_idx = 5;
 195 name5_10:
 196         end_idx -= 5;
 197         for (; end_idx < 6; end_idx++) {
 198                 slotptr->name5_10[end_idx * 2] = 0xff;
 199                 slotptr->name5_10[end_idx * 2 + 1] = 0xff;
 200         }
 201         end_idx = 11;
 202 name11_12:
 203         end_idx -= 11;
 204         for (; end_idx < 2; end_idx++) {
 205                 slotptr->name11_12[end_idx * 2] = 0xff;
 206                 slotptr->name11_12[end_idx * 2 + 1] = 0xff;
 207         }
 208
 209         return 1;
 210 }
 211
 212 static int flush_dir_table(fat_itr *itr);
 213
 214 /*
 215  * Fill dir_slot entries with appropriate name, id, and attr
 216  * 'itr' will point to a next entry
 217  */
 218 static int
 219 fill_dir_slot(fat_itr *itr, const char *l_name)
 220 {
 221         __u8 temp_dir_slot_buffer[MAX_LFN_SLOT * sizeof(dir_slot)];
 222         dir_slot *slotptr = (dir_slot *)temp_dir_slot_buffer;
 223         __u8 counter = 0, checksum;
 224         int idx = 0, ret;
 225
 226         /* Get short file name checksum value */
 227         checksum = mkcksum(itr->dent->name, itr->dent->ext);
 228
 229         do {
 230                 memset(slotptr, 0x00, sizeof(dir_slot));
 231                 ret = str2slot(slotptr, l_name, &idx);
 232                 slotptr->id = ++counter;
 233                 slotptr->attr = ATTR_VFAT;
 234                 slotptr->alias_checksum = checksum;
 235                 slotptr++;
 236         } while (ret == 0);
 237
 238         slotptr--;
 239         slotptr->id |= LAST_LONG_ENTRY_MASK;
 240
 241         while (counter >= 1) {
 242                 memcpy(itr->dent, slotptr, sizeof(dir_slot));
 243                 slotptr--;
 244                 counter--;
 245                 if (!fat_itr_next(itr))
 246                         if (!itr->dent && !itr->is_root && flush_dir_table(itr))
 247                                 return -1;
 248         }
 249
 250         if (!itr->dent && !itr->is_root)
 251                 /*
 252                  * don't care return value here because we have already
 253                  * finished completing an entry with name, only ending up
 254                  * no more entry left
 255                  */
 256                 flush_dir_table(itr);
 257
 258         return 0;
 259 }
 260
 261 /*
 262  * Set the entry at index 'entry' in a FAT (12/16/32) table.
 263  */
 264 static int set_fatent_value(fsdata *mydata, __u32 entry, __u32 entry_value)
 265 {
 266         __u32 bufnum, offset, off16;
 267         __u16 val1, val2;
 268
 269         switch (mydata->fatsize) {
 270         case 32:
 271                 bufnum = entry / FAT32BUFSIZE;
 272                 offset = entry - bufnum * FAT32BUFSIZE;
 273                 break;
 274         case 16:
 275                 bufnum = entry / FAT16BUFSIZE;
 276                 offset = entry - bufnum * FAT16BUFSIZE;
 277                 break;
 278         case 12:
 279                 bufnum = entry / FAT12BUFSIZE;
 280                 offset = entry - bufnum * FAT12BUFSIZE;
 281                 break;
 282         default:
 283                 /* Unsupported FAT size */
 284                 return -1;
 285         }
 286
 287         /* Read a new block of FAT entries into the cache. */
 288         if (bufnum != mydata->fatbufnum) {
 289                 int getsize = FATBUFBLOCKS;
 290                 __u8 *bufptr = mydata->fatbuf;
 291                 __u32 fatlength = mydata->fatlength;
 292                 __u32 startblock = bufnum * FATBUFBLOCKS;
 293
 294                 /* Cap length if fatlength is not a multiple of FATBUFBLOCKS */
 295                 if (startblock + getsize > fatlength)
 296                         getsize = fatlength - startblock;
 297
 298                 if (flush_dirty_fat_buffer(mydata) < 0)
 299                         return -1;
 300
 301                 startblock += mydata->fat_sect;
 302
 303                 if (disk_read(startblock, getsize, bufptr) < 0) {
 304                         debug("Error reading FAT blocks\n");
 305                         return -1;
 306                 }
 307                 mydata->fatbufnum = bufnum;
 308         }
 309
 310         /* Mark as dirty */
 311         mydata->fat_dirty = 1;
 312
 313         /* Set the actual entry */
 314         switch (mydata->fatsize) {
 315         case 32:
 316                 ((__u32 *) mydata->fatbuf)[offset] = cpu_to_le32(entry_value);
 317                 break;
 318         case 16:
 319                 ((__u16 *) mydata->fatbuf)[offset] = cpu_to_le16(entry_value);
 320                 break;
 321         case 12:
 322                 off16 = (offset * 3) / 4;
 323
 324                 switch (offset & 0x3) {
 325                 case 0:
 326                         val1 = cpu_to_le16(entry_value) & 0xfff;
 327                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff;
 328                         ((__u16 *)mydata->fatbuf)[off16] |= val1;
 329                         break;
 330                 case 1:
 331                         val1 = cpu_to_le16(entry_value) & 0xf;
 332                         val2 = (cpu_to_le16(entry_value) >> 4) & 0xff;
 333
 334                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xf000;
 335                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 12);
 336
 337                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xff;
 338                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 339                         break;
 340                 case 2:
 341                         val1 = cpu_to_le16(entry_value) & 0xff;
 342                         val2 = (cpu_to_le16(entry_value) >> 8) & 0xf;
 343
 344                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xff00;
 345                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 8);
 346
 347                         ((__u16 *)mydata->fatbuf)[off16 + 1] &= ~0xf;
 348                         ((__u16 *)mydata->fatbuf)[off16 + 1] |= val2;
 349                         break;
 350                 case 3:
 351                         val1 = cpu_to_le16(entry_value) & 0xfff;
 352                         ((__u16 *)mydata->fatbuf)[off16] &= ~0xfff0;
 353                         ((__u16 *)mydata->fatbuf)[off16] |= (val1 << 4);
 354                         break;
 355                 default:
 356                         break;
 357                 }
 358
 359                 break;
 360         default:
 361                 return -1;
 362         }
 363
 364         return 0;
 365 }
 366
 367 /*
 368  * Determine the next free cluster after 'entry' in a FAT (12/16/32) table
 369  * and link it to 'entry'. EOC marker is not set on returned entry.
 370  */
 371 static __u32 determine_fatent(fsdata *mydata, __u32 entry)
 372 {
 373         __u32 next_fat, next_entry = entry + 1;
 374
 375         while (1) {
 376                 next_fat = get_fatent(mydata, next_entry);
 377                 if (next_fat == 0) {
 378                         /* found free entry, link to entry */
 379                         set_fatent_value(mydata, entry, next_entry);
 380                         break;
 381                 }
 382                 next_entry++;
 383         }
 384         debug("FAT%d: entry: %08x, entry_value: %04x\n",
 385                mydata->fatsize, entry, next_entry);
 386
 387         return next_entry;
 388 }
 389
 390 /*
 391  * Write at most 'size' bytes from 'buffer' into the specified cluster.
 392  * Return 0 on success, -1 otherwise.
 393  */
 394 static int
 395 set_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer,
 396              unsigned long size)
 397 {
 398         __u32 idx = 0;
 399         __u32 startsect;
 400         int ret;
 401
 402         if (clustnum > 0)
 403                 startsect = clust_to_sect(mydata, clustnum);
 404         else
 405                 startsect = mydata->rootdir_sect;
 406
 407         debug("clustnum: %d, startsect: %d\n", clustnum, startsect);
 408
 409         if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 410                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 411
 412                 printf("FAT: Misaligned buffer address (%p)\n", buffer);
 413
 414                 while (size >= mydata->sect_size) {
 415                         memcpy(tmpbuf, buffer, mydata->sect_size);
 416                         ret = disk_write(startsect++, 1, tmpbuf);
 417                         if (ret != 1) {
 418                                 debug("Error writing data (got %d)\n", ret);
 419                                 return -1;
 420                         }
 421
 422                         buffer += mydata->sect_size;
 423                         size -= mydata->sect_size;
 424                 }
 425         } else if (size >= mydata->sect_size) {
 426                 idx = size / mydata->sect_size;
 427                 ret = disk_write(startsect, idx, buffer);
 428                 if (ret != idx) {
 429                         debug("Error writing data (got %d)\n", ret);
 430                         return -1;
 431                 }
 432
 433                 startsect += idx;
 434                 idx *= mydata->sect_size;
 435                 buffer += idx;
 436                 size -= idx;
 437         }
 438
 439         if (size) {
 440                 ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 441
 442                 memcpy(tmpbuf, buffer, size);
 443                 ret = disk_write(startsect, 1, tmpbuf);
 444                 if (ret != 1) {
 445                         debug("Error writing data (got %d)\n", ret);
 446                         return -1;
 447                 }
 448         }
 449
 450         return 0;
 451 }
 452
 453 /*
 454  * Find the first empty cluster
 455  */
 456 static int find_empty_cluster(fsdata *mydata)
 457 {
 458         __u32 fat_val, entry = 3;
 459
 460         while (1) {
 461                 fat_val = get_fatent(mydata, entry);
 462                 if (fat_val == 0)
 463                         break;
 464                 entry++;
 465         }
 466
 467         return entry;
 468 }
 469
 470 /*
 471  * Write directory entries in itr's buffer to block device
 472  */
 473 static int flush_dir_table(fat_itr *itr)
 474 {
 475         fsdata *mydata = itr->fsdata;
 476         int dir_newclust = 0;
 477         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 478
 479         if (set_cluster(mydata, itr->clust, itr->block, bytesperclust) != 0) {
 480                 printf("error: writing directory entry\n");
 481                 return -1;
 482         }
 483         dir_newclust = find_empty_cluster(mydata);
 484         set_fatent_value(mydata, itr->clust, dir_newclust);
 485         if (mydata->fatsize == 32)
 486                 set_fatent_value(mydata, dir_newclust, 0xffffff8);
 487         else if (mydata->fatsize == 16)
 488                 set_fatent_value(mydata, dir_newclust, 0xfff8);
 489         else if (mydata->fatsize == 12)
 490                 set_fatent_value(mydata, dir_newclust, 0xff8);
 491
 492         itr->clust = dir_newclust;
 493         itr->next_clust = dir_newclust;
 494
 495         if (flush_dirty_fat_buffer(mydata) < 0)
 496                 return -1;
 497
 498         memset(itr->block, 0x00, bytesperclust);
 499
 500         itr->dent = (dir_entry *)itr->block;
 501         itr->last_cluster = 1;
 502         itr->remaining = bytesperclust / sizeof(dir_entry) - 1;
 503
 504         return 0;
 505 }
 506
 507 /*
 508  * Set empty cluster from 'entry' to the end of a file
 509  */
 510 static int clear_fatent(fsdata *mydata, __u32 entry)
 511 {
 512         __u32 fat_val;
 513
 514         while (!CHECK_CLUST(entry, mydata->fatsize)) {
 515                 fat_val = get_fatent(mydata, entry);
 516                 if (fat_val != 0)
 517                         set_fatent_value(mydata, entry, 0);
 518                 else
 519                         break;
 520
 521                 entry = fat_val;
 522         }
 523
 524         /* Flush fat buffer */
 525         if (flush_dirty_fat_buffer(mydata) < 0)
 526                 return -1;
 527
 528         return 0;
 529 }
 530
 531 /*
 532  * Write at most 'maxsize' bytes from 'buffer' into
 533  * the file associated with 'dentptr'
 534  * Update the number of bytes written in *gotsize and return 0
 535  * or return -1 on fatal errors.
 536  */
 537 static int
 538 set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
 539               loff_t maxsize, loff_t *gotsize)
 540 {
 541         loff_t filesize = FAT2CPU32(dentptr->size);
 542         unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 543         __u32 curclust = START(dentptr);
 544         __u32 endclust = 0, newclust = 0;
 545         loff_t actsize;
 546
 547         *gotsize = 0;
 548         debug("Filesize: %llu bytes\n", filesize);
 549
 550         if (maxsize > 0 && filesize > maxsize)
 551                 filesize = maxsize;
 552
 553         debug("%llu bytes\n", filesize);
 554
 555         if (!curclust) {
 556                 if (filesize) {
 557                         debug("error: nonempty clusterless file!\n");
 558                         return -1;
 559                 }
 560                 return 0;
 561         }
 562
 563         actsize = bytesperclust;
 564         endclust = curclust;
 565         do {
 566                 /* search for consecutive clusters */
 567                 while (actsize < filesize) {
 568                         newclust = determine_fatent(mydata, endclust);
 569
 570                         if ((newclust - 1) != endclust)
 571                                 goto getit;
 572
 573                         if (CHECK_CLUST(newclust, mydata->fatsize)) {
 574                                 debug("newclust: 0x%x\n", newclust);
 575                                 debug("Invalid FAT entry\n");
 576                                 return 0;
 577                         }
 578                         endclust = newclust;
 579                         actsize += bytesperclust;
 580                 }
 581
 582                 /* set remaining bytes */
 583                 actsize = filesize;
 584                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 585                         debug("error: writing cluster\n");
 586                         return -1;
 587                 }
 588                 *gotsize += actsize;
 589
 590                 /* Mark end of file in FAT */
 591                 if (mydata->fatsize == 12)
 592                         newclust = 0xfff;
 593                 else if (mydata->fatsize == 16)
 594                         newclust = 0xffff;
 595                 else if (mydata->fatsize == 32)
 596                         newclust = 0xfffffff;
 597                 set_fatent_value(mydata, endclust, newclust);
 598
 599                 return 0;
 600 getit:
 601                 if (set_cluster(mydata, curclust, buffer, (int)actsize) != 0) {
 602                         debug("error: writing cluster\n");
 603                         return -1;
 604                 }
 605                 *gotsize += actsize;
 606                 filesize -= actsize;
 607                 buffer += actsize;
 608
 609                 if (CHECK_CLUST(newclust, mydata->fatsize)) {
 610                         debug("newclust: 0x%x\n", newclust);
 611                         debug("Invalid FAT entry\n");
 612                         return 0;
 613                 }
 614                 actsize = bytesperclust;
 615                 curclust = endclust = newclust;
 616         } while (1);
 617 }
 618
 619 /*
 620  * Set start cluster in directory entry
 621  */
 622 static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr,
 623                                 __u32 start_cluster)
 624 {
 625         if (mydata->fatsize == 32)
 626                 dentptr->starthi =
 627                         cpu_to_le16((start_cluster & 0xffff0000) >> 16);
 628         dentptr->start = cpu_to_le16(start_cluster & 0xffff);
 629 }
 630
 631 /*
 632  * Fill dir_entry
 633  */
 634 static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 635         const char *filename, __u32 start_cluster, __u32 size, __u8 attr)
 636 {
 637         set_start_cluster(mydata, dentptr, start_cluster);
 638         dentptr->size = cpu_to_le32(size);
 639
 640         dentptr->attr = attr;
 641
 642         set_name(dentptr, filename);
 643 }
 644
 645 /*
 646  * Check whether adding a file makes the file system to
 647  * exceed the size of the block device
 648  * Return -1 when overflow occurs, otherwise return 0
 649  */
 650 static int check_overflow(fsdata *mydata, __u32 clustnum, loff_t size)
 651 {
 652         __u32 startsect, sect_num, offset;
 653
 654         if (clustnum > 0) {
 655                 startsect = clust_to_sect(mydata, clustnum);
 656         } else {
 657                 startsect = mydata->rootdir_sect;
 658         }
 659
 660         sect_num = div_u64_rem(size, mydata->sect_size, &offset);
 661
 662         if (offset != 0)
 663                 sect_num++;
 664
 665         if (startsect + sect_num > total_sector)
 666                 return -1;
 667         return 0;
 668 }
 669
 670 /*
 671  * Find a directory entry based on filename or start cluster number
 672  * If the directory entry is not found,
 673  * the new position for writing a directory entry will be returned
 674  */
 675 static dir_entry *find_directory_entry(fat_itr *itr, char *filename)
 676 {
 677         int match = 0;
 678
 679         while (fat_itr_next(itr)) {
 680                 /* check both long and short name: */
 681                 if (!strcasecmp(filename, itr->name))
 682                         match = 1;
 683                 else if (itr->name != itr->s_name &&
 684                          !strcasecmp(filename, itr->s_name))
 685                         match = 1;
 686
 687                 if (!match)
 688                         continue;
 689
 690                 if (itr->dent->name[0] == '\0')
 691                         return NULL;
 692                 else
 693                         return itr->dent;
 694         }
 695
 696         if (!itr->dent && !itr->is_root && flush_dir_table(itr))
 697                 /* indicate that allocating dent failed */
 698                 itr->dent = NULL;
 699
 700         return NULL;
 701 }
 702
 703 static int split_filename(char *filename, char **dirname, char **basename)
 704 {
 705         char *p, *last_slash, *last_slash_cont;
 706
 707 again:
 708         p = filename;
 709         last_slash = NULL;
 710         last_slash_cont = NULL;
 711         while (*p) {
 712                 if (ISDIRDELIM(*p)) {
 713                         last_slash = p;
 714                         last_slash_cont = p;
 715                         /* continuous slashes */
 716                         while (ISDIRDELIM(*p))
 717                                 last_slash_cont = p++;
 718                         if (!*p)
 719                                 break;
 720                 }
 721                 p++;
 722         }
 723
 724         if (last_slash) {
 725                 if (last_slash_cont == (filename + strlen(filename) - 1)) {
 726                         /* remove trailing slashes */
 727                         *last_slash = '\0';
 728                         goto again;
 729                 }
 730
 731                 if (last_slash == filename) {
 732                         /* avoid ""(null) directory */
 733                         *dirname = "/";
 734                 } else {
 735                         *last_slash = '\0';
 736                         *dirname = filename;
 737                 }
 738
 739                 *last_slash_cont = '\0';
 740                 *basename = last_slash_cont + 1;
 741         } else {
 742                 *dirname = "/"; /* root by default */
 743                 *basename = filename;
 744         }
 745
 746         return 0;
 747 }
 748
 749 static int normalize_longname(char *l_filename, const char *filename)
 750 {
 751         const char *p, legal[] = "!#$%&\'()-.@^`_{}~";
 752         char c;
 753         int name_len;
 754
 755         /* Check that the filename is valid */
 756         for (p = filename; p < filename + strlen(filename); p++) {
 757                 c = *p;
 758
 759                 if (('0' <= c) && (c <= '9'))
 760                         continue;
 761                 if (('A' <= c) && (c <= 'Z'))
 762                         continue;
 763                 if (('a' <= c) && (c <= 'z'))
 764                         continue;
 765                 if (strchr(legal, c))
 766                         continue;
 767                 /* extended code */
 768                 if ((0x80 <= c) && (c <= 0xff))
 769                         continue;
 770
 771                 return -1;
 772         }
 773
 774         /* Normalize it */
 775         name_len = strlen(filename);
 776         if (name_len >= VFAT_MAXLEN_BYTES)
 777                 /* should return an error? */
 778                 name_len = VFAT_MAXLEN_BYTES - 1;
 779
 780         memcpy(l_filename, filename, name_len);
 781         l_filename[name_len] = 0; /* terminate the string */
 782         downcase(l_filename, INT_MAX);
 783
 784         return 0;
 785 }
 786
 787 static int do_fat_write(const char *filename, void *buffer, loff_t size,
 788                         loff_t *actwrite)
 789 {
 790         dir_entry *retdent;
 791         __u32 start_cluster;
 792         fsdata datablock = { .fatbuf = NULL, };
 793         fsdata *mydata = &datablock;
 794         fat_itr *itr = NULL;
 795         int ret = -1;
 796         char *filename_copy, *parent, *basename;
 797         char l_filename[VFAT_MAXLEN_BYTES];
 798
 799         filename_copy = strdup(filename);
 800         if (!filename_copy)
 801                 return -ENOMEM;
 802
 803         split_filename(filename_copy, &parent, &basename);
 804         if (!strlen(basename)) {
 805                 ret = -EINVAL;
 806                 goto exit;
 807         }
 808
 809         filename = basename;
 810         if (normalize_longname(l_filename, filename)) {
 811                 printf("FAT: illegal filename (%s)\n", filename);
 812                 ret = -EINVAL;
 813                 goto exit;
 814         }
 815
 816         itr = malloc_cache_aligned(sizeof(fat_itr));
 817         if (!itr) {
 818                 ret = -ENOMEM;
 819                 goto exit;
 820         }
 821
 822         ret = fat_itr_root(itr, &datablock);
 823         if (ret)
 824                 goto exit;
 825
 826         total_sector = datablock.total_sect;
 827
 828         ret = fat_itr_resolve(itr, parent, TYPE_DIR);
 829         if (ret) {
 830                 printf("%s: doesn't exist (%d)\n", parent, ret);
 831                 goto exit;
 832         }
 833
 834         retdent = find_directory_entry(itr, l_filename);
 835
 836         if (retdent) {
 837                 if (fat_itr_isdir(itr)) {
 838                         ret = -EISDIR;
 839                         goto exit;
 840                 }
 841
 842                 /* Update file size and start_cluster in a directory entry */
 843                 retdent->size = cpu_to_le32(size);
 844                 start_cluster = START(retdent);
 845
 846                 if (start_cluster) {
 847                         if (size) {
 848                                 ret = check_overflow(mydata, start_cluster,
 849                                                         size);
 850                                 if (ret) {
 851                                         printf("Error: %llu overflow\n", size);
 852                                         ret = -ENOSPC;
 853                                         goto exit;
 854                                 }
 855                         }
 856
 857                         ret = clear_fatent(mydata, start_cluster);
 858                         if (ret) {
 859                                 printf("Error: clearing FAT entries\n");
 860                                 ret = -EIO;
 861                                 goto exit;
 862                         }
 863
 864                         if (!size)
 865                                 set_start_cluster(mydata, retdent, 0);
 866                 } else if (size) {
 867                         ret = start_cluster = find_empty_cluster(mydata);
 868                         if (ret < 0) {
 869                                 printf("Error: finding empty cluster\n");
 870                                 ret = -ENOSPC;
 871                                 goto exit;
 872                         }
 873
 874                         ret = check_overflow(mydata, start_cluster, size);
 875                         if (ret) {
 876                                 printf("Error: %llu overflow\n", size);
 877                                 ret = -ENOSPC;
 878                                 goto exit;
 879                         }
 880
 881                         set_start_cluster(mydata, retdent, start_cluster);
 882                 }
 883         } else {
 884                 /* Create a new file */
 885
 886                 if (itr->is_root) {
 887                         /* root dir cannot have "." or ".." */
 888                         if (!strcmp(l_filename, ".") ||
 889                             !strcmp(l_filename, "..")) {
 890                                 ret = -EINVAL;
 891                                 goto exit;
 892                         }
 893                 }
 894
 895                 if (!itr->dent) {
 896                         printf("Error: allocating new dir entry\n");
 897                         ret = -EIO;
 898                         goto exit;
 899                 }
 900
 901                 memset(itr->dent, 0, sizeof(*itr->dent));
 902
 903                 /* Set short name to set alias checksum field in dir_slot */
 904                 set_name(itr->dent, filename);
 905                 if (fill_dir_slot(itr, filename)) {
 906                         ret = -EIO;
 907                         goto exit;
 908                 }
 909
 910                 if (size) {
 911                         ret = start_cluster = find_empty_cluster(mydata);
 912                         if (ret < 0) {
 913                                 printf("Error: finding empty cluster\n");
 914                                 ret = -ENOSPC;
 915                                 goto exit;
 916                         }
 917
 918                         ret = check_overflow(mydata, start_cluster, size);
 919                         if (ret) {
 920                                 printf("Error: %llu overflow\n", size);
 921                                 ret = -ENOSPC;
 922                                 goto exit;
 923                         }
 924                 } else {
 925                         start_cluster = 0;
 926                 }
 927
 928                 /* Set attribute as archive for regular file */
 929                 fill_dentry(itr->fsdata, itr->dent, filename,
 930                             start_cluster, size, 0x20);
 931
 932                 retdent = itr->dent;
 933         }
 934
 935         ret = set_contents(mydata, retdent, buffer, size, actwrite);
 936         if (ret < 0) {
 937                 printf("Error: writing contents\n");
 938                 ret = -EIO;
 939                 goto exit;
 940         }
 941         debug("attempt to write 0x%llx bytes\n", *actwrite);
 942
 943         /* Flush fat buffer */
 944         ret = flush_dirty_fat_buffer(mydata);
 945         if (ret) {
 946                 printf("Error: flush fat buffer\n");
 947                 ret = -EIO;
 948                 goto exit;
 949         }
 950
 951         /* Write directory table to device */
 952         ret = set_cluster(mydata, itr->clust, itr->block,
 953                           mydata->clust_size * mydata->sect_size);
 954         if (ret) {
 955                 printf("Error: writing directory entry\n");
 956                 ret = -EIO;
 957         }
 958
 959 exit:
 960         free(filename_copy);
 961         free(mydata->fatbuf);
 962         free(itr);
 963         return ret;
 964 }
 965
 966 int file_fat_write(const char *filename, void *buffer, loff_t offset,
 967                    loff_t maxsize, loff_t *actwrite)
 968 {
 969         if (offset != 0) {
 970                 printf("Error: non zero offset is currently not supported.\n");
 971                 return -EINVAL;
 972         }
 973
 974         printf("writing %s\n", filename);
 975         return do_fat_write(filename, buffer, maxsize, actwrite);
 976 }