sbin/fsck_msdosfs/fat.c

   1 /*
   2  * Copyright (C) 1995, 1996, 1997 Wolfgang Solfrank
   3  * Copyright (c) 1995 Martin Husemann
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Martin Husemann
  16  *      and Wolfgang Solfrank.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
  22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  24  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * $NetBSD: fat.c,v 1.12 2000/10/10 20:24:52 is Exp $
  33  * $FreeBSD: src/sbin/fsck_msdosfs/fat.c,v 1.1.2.1 2001/08/01 05:47:56 obrien Exp $
  34  * $DragonFly: src/sbin/fsck_msdosfs/fat.c,v 1.4 2003/11/01 17:15:58 drhodus Exp $
  35  */
  36
  37
  38 #include <sys/cdefs.h>
  39
  40 #include <stdlib.h>
  41 #include <string.h>
  42 #include <ctype.h>
  43 #include <stdio.h>
  44 #include <unistd.h>
  45
  46 #include "ext.h"
  47 #include "fsutil.h"
  48
  49 static int checkclnum(struct bootblock *, int, cl_t, cl_t *);
  50 static int clustdiffer(cl_t, cl_t *, cl_t *, int);
  51 static int tryclear(struct bootblock *, struct fatEntry *, cl_t, cl_t *);
  52 static int _readfat(int, struct bootblock *, int, u_char **);
  53
  54 /*
  55  * Check a cluster number for valid value
  56  */
  57 static int
  58 checkclnum(struct bootblock *boot, int fat, cl_t cl, cl_t *next)
  59 {
  60         if (*next >= (CLUST_RSRVD&boot->ClustMask))
  61                 *next |= ~boot->ClustMask;
  62         if (*next == CLUST_FREE) {
  63                 boot->NumFree++;
  64                 return FSOK;
  65         }
  66         if (*next == CLUST_BAD) {
  67                 boot->NumBad++;
  68                 return FSOK;
  69         }
  70         if (*next < CLUST_FIRST
  71             || (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
  72                 pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
  73                       cl, fat,
  74                       *next < CLUST_RSRVD ? "out of range" : "reserved",
  75                       *next&boot->ClustMask);
  76                 if (ask(0, "Truncate")) {
  77                         *next = CLUST_EOF;
  78                         return FSFATMOD;
  79                 }
  80                 return FSERROR;
  81         }
  82         return FSOK;
  83 }
  84
  85 /*
  86  * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
  87  */
  88 static int
  89 _readfat(int fs, struct bootblock *boot, int no, u_char **buffer)
  90 {
  91         off_t off;
  92
  93         *buffer = malloc(boot->FATsecs * boot->BytesPerSec);
  94         if (*buffer == NULL) {
  95                 perror("No space for FAT");
  96                 return 0;
  97         }
  98
  99         off = boot->ResSectors + no * boot->FATsecs;
 100         off *= boot->BytesPerSec;
 101
 102         if (lseek(fs, off, SEEK_SET) != off) {
 103                 perror("Unable to read FAT");
 104                 goto err;
 105         }
 106
 107         if (read(fs, *buffer, boot->FATsecs * boot->BytesPerSec)
 108             != boot->FATsecs * boot->BytesPerSec) {
 109                 perror("Unable to read FAT");
 110                 goto err;
 111         }
 112
 113         return 1;
 114
 115     err:
 116         free(*buffer);
 117         return 0;
 118 }
 119
 120 /*
 121  * Read a FAT and decode it into internal format
 122  */
 123 int
 124 readfat(int fs, struct bootblock *boot, int no, struct fatEntry **fp)
 125 {
 126         struct fatEntry *fat;
 127         u_char *buffer, *p;
 128         cl_t cl;
 129         int ret = FSOK;
 130
 131         boot->NumFree = boot->NumBad = 0;
 132
 133         if (!_readfat(fs, boot, no, &buffer))
 134                 return FSFATAL;
 135
 136         fat = calloc(boot->NumClusters, sizeof(struct fatEntry));
 137         if (fat == NULL) {
 138                 perror("No space for FAT");
 139                 free(buffer);
 140                 return FSFATAL;
 141         }
 142
 143         if (buffer[0] != boot->Media
 144             || buffer[1] != 0xff || buffer[2] != 0xff
 145             || (boot->ClustMask == CLUST16_MASK && buffer[3] != 0xff)
 146             || (boot->ClustMask == CLUST32_MASK
 147                 && ((buffer[3]&0x0f) != 0x0f
 148                     || buffer[4] != 0xff || buffer[5] != 0xff
 149                     || buffer[6] != 0xff || (buffer[7]&0x0f) != 0x0f))) {
 150
 151                 /* Windows 95 OSR2 (and possibly any later) changes
 152                  * the FAT signature to 0xXXffff7f for FAT16 and to
 153                  * 0xXXffff0fffffff07 for FAT32 upon boot, to know that the
 154                  * filesystem is dirty if it doesn't reboot cleanly.
 155                  * Check this special condition before errorring out.
 156                  */
 157                 if (buffer[0] == boot->Media && buffer[1] == 0xff
 158                     && buffer[2] == 0xff
 159                     && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
 160                         || (boot->ClustMask == CLUST32_MASK
 161                             && buffer[3] == 0x0f && buffer[4] == 0xff
 162                             && buffer[5] == 0xff && buffer[6] == 0xff
 163                             && buffer[7] == 0x07)))
 164                         ret |= FSDIRTY;
 165                 else {
 166                         /* just some odd byte sequence in FAT */
 167
 168                         switch (boot->ClustMask) {
 169                         case CLUST32_MASK:
 170                                 pwarn("%s (%02x%02x%02x%02x%02x%02x%02x%02x)\n",
 171                                       "FAT starts with odd byte sequence",
 172                                       buffer[0], buffer[1], buffer[2], buffer[3],
 173                                       buffer[4], buffer[5], buffer[6], buffer[7]);
 174                                 break;
 175                         case CLUST16_MASK:
 176                                 pwarn("%s (%02x%02x%02x%02x)\n",
 177                                     "FAT starts with odd byte sequence",
 178                                     buffer[0], buffer[1], buffer[2], buffer[3]);
 179                                 break;
 180                         default:
 181                                 pwarn("%s (%02x%02x%02x)\n",
 182                                     "FAT starts with odd byte sequence",
 183                                     buffer[0], buffer[1], buffer[2]);
 184                                 break;
 185                         }
 186
 187
 188                         if (ask(1, "Correct"))
 189                                 ret |= FSFIXFAT;
 190                 }
 191         }
 192         switch (boot->ClustMask) {
 193         case CLUST32_MASK:
 194                 p = buffer + 8;
 195                 break;
 196         case CLUST16_MASK:
 197                 p = buffer + 4;
 198                 break;
 199         default:
 200                 p = buffer + 3;
 201                 break;
 202         }
 203         for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
 204                 switch (boot->ClustMask) {
 205                 case CLUST32_MASK:
 206                         fat[cl].next = p[0] + (p[1] << 8)
 207                                        + (p[2] << 16) + (p[3] << 24);
 208                         fat[cl].next &= boot->ClustMask;
 209                         ret |= checkclnum(boot, no, cl, &fat[cl].next);
 210                         cl++;
 211                         p += 4;
 212                         break;
 213                 case CLUST16_MASK:
 214                         fat[cl].next = p[0] + (p[1] << 8);
 215                         ret |= checkclnum(boot, no, cl, &fat[cl].next);
 216                         cl++;
 217                         p += 2;
 218                         break;
 219                 default:
 220                         fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
 221                         ret |= checkclnum(boot, no, cl, &fat[cl].next);
 222                         cl++;
 223                         if (cl >= boot->NumClusters)
 224                                 break;
 225                         fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
 226                         ret |= checkclnum(boot, no, cl, &fat[cl].next);
 227                         cl++;
 228                         p += 3;
 229                         break;
 230                 }
 231         }
 232
 233         free(buffer);
 234         *fp = fat;
 235         return ret;
 236 }
 237
 238 /*
 239  * Get type of reserved cluster
 240  */
 241 char *
 242 rsrvdcltype(cl_t cl)
 243 {
 244         if (cl == CLUST_FREE)
 245                 return "free";
 246         if (cl < CLUST_BAD)
 247                 return "reserved";
 248         if (cl > CLUST_BAD)
 249                 return "as EOF";
 250         return "bad";
 251 }
 252
 253 static int
 254 clustdiffer(cl_t cl, cl_t *cp1, cl_t *cp2, int fatnum)
 255 {
 256         if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
 257                 if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
 258                         if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
 259                              && *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
 260                             || (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
 261                                 pwarn("Cluster %u is marked %s with different indicators, ",
 262                                       cl, rsrvdcltype(*cp1));
 263                                 if (ask(1, "fix")) {
 264                                         *cp2 = *cp1;
 265                                         return FSFATMOD;
 266                                 }
 267                                 return FSFATAL;
 268                         }
 269                         pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %d\n",
 270                               cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
 271                         if (ask(0, "use FAT 0's entry")) {
 272                                 *cp2 = *cp1;
 273                                 return FSFATMOD;
 274                         }
 275                         if (ask(0, "use FAT %d's entry", fatnum)) {
 276                                 *cp1 = *cp2;
 277                                 return FSFATMOD;
 278                         }
 279                         return FSFATAL;
 280                 }
 281                 pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
 282                       cl, rsrvdcltype(*cp1), *cp2, fatnum);
 283                 if (ask(0, "Use continuation from FAT %d", fatnum)) {
 284                         *cp1 = *cp2;
 285                         return FSFATMOD;
 286                 }
 287                 if (ask(0, "Use mark from FAT 0")) {
 288                         *cp2 = *cp1;
 289                         return FSFATMOD;
 290                 }
 291                 return FSFATAL;
 292         }
 293         if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
 294                 pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %d\n",
 295                       cl, *cp1, rsrvdcltype(*cp2), fatnum);
 296                 if (ask(0, "Use continuation from FAT 0")) {
 297                         *cp2 = *cp1;
 298                         return FSFATMOD;
 299                 }
 300                 if (ask(0, "Use mark from FAT %d", fatnum)) {
 301                         *cp1 = *cp2;
 302                         return FSFATMOD;
 303                 }
 304                 return FSERROR;
 305         }
 306         pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %d\n",
 307               cl, *cp1, *cp2, fatnum);
 308         if (ask(0, "Use continuation from FAT 0")) {
 309                 *cp2 = *cp1;
 310                 return FSFATMOD;
 311         }
 312         if (ask(0, "Use continuation from FAT %d", fatnum)) {
 313                 *cp1 = *cp2;
 314                 return FSFATMOD;
 315         }
 316         return FSERROR;
 317 }
 318
 319 /*
 320  * Compare two FAT copies in memory. Resolve any conflicts and merge them
 321  * into the first one.
 322  */
 323 int
 324 comparefat(struct bootblock *boot, struct fatEntry *first,
 325            struct fatEntry *second, int fatnum)
 326 {
 327         cl_t cl;
 328         int ret = FSOK;
 329
 330         for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
 331                 if (first[cl].next != second[cl].next)
 332                         ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
 333         return ret;
 334 }
 335
 336 void
 337 clearchain(struct bootblock *boot, struct fatEntry *fat, cl_t head)
 338 {
 339         cl_t p, q;
 340
 341         for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
 342                 if (fat[p].head != head)
 343                         break;
 344                 q = fat[p].next;
 345                 fat[p].next = fat[p].head = CLUST_FREE;
 346                 fat[p].length = 0;
 347         }
 348 }
 349
 350 int
 351 tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *trunc)
 352 {
 353         if (ask(0, "Clear chain starting at %u", head)) {
 354                 clearchain(boot, fat, head);
 355                 return FSFATMOD;
 356         } else if (ask(0, "Truncate")) {
 357                 *trunc = CLUST_EOF;
 358                 return FSFATMOD;
 359         } else
 360                 return FSERROR;
 361 }
 362
 363 /*
 364  * Check a complete FAT in-memory for crosslinks
 365  */
 366 int
 367 checkfat(struct bootblock *boot, struct fatEntry *fat)
 368 {
 369         cl_t head, p, h, n;
 370         u_int len;
 371         int ret = 0;
 372         int conf;
 373
 374         /*
 375          * pass 1: figure out the cluster chains.
 376          */
 377         for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
 378                 /* find next untravelled chain */
 379                 if (fat[head].head != 0         /* cluster already belongs to some chain */
 380                     || fat[head].next == CLUST_FREE
 381                     || fat[head].next == CLUST_BAD)
 382                         continue;               /* skip it. */
 383
 384                 /* follow the chain and mark all clusters on the way */
 385                 for (len = 0, p = head;
 386                      p >= CLUST_FIRST && p < boot->NumClusters;
 387                      p = fat[p].next) {
 388                         fat[p].head = head;
 389                         len++;
 390                 }
 391
 392                 /* the head record gets the length */
 393                 fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
 394         }
 395
 396         /*
 397          * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
 398          * we didn't know the real start of the chain then - would have treated partial
 399          * chains as interlinked with their main chain)
 400          */
 401         for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
 402                 /* find next untravelled chain */
 403                 if (fat[head].head != head)
 404                         continue;
 405
 406                 /* follow the chain to its end (hopefully) */
 407                 for (p = head;
 408                      (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
 409                      p = n)
 410                         if (fat[n].head != head)
 411                                 break;
 412                 if (n >= CLUST_EOFS)
 413                         continue;
 414
 415                 if (n == CLUST_FREE || n >= CLUST_RSRVD) {
 416                         pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
 417                               head, rsrvdcltype(n));
 418                         ret |= tryclear(boot, fat, head, &fat[p].next);
 419                         continue;
 420                 }
 421                 if (n < CLUST_FIRST || n >= boot->NumClusters) {
 422                         pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
 423                               head, n);
 424                         ret |= tryclear(boot, fat, head, &fat[p].next);
 425                         continue;
 426                 }
 427                 pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
 428                       head, fat[n].head, n);
 429                 conf = tryclear(boot, fat, head, &fat[p].next);
 430                 if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
 431                         if (conf == FSERROR) {
 432                                 /*
 433                                  * Transfer the common chain to the one not cleared above.
 434                                  */
 435                                 for (p = n;
 436                                      p >= CLUST_FIRST && p < boot->NumClusters;
 437                                      p = fat[p].next) {
 438                                         if (h != fat[p].head) {
 439                                                 /*
 440                                                  * Have to reexamine this chain.
 441                                                  */
 442                                                 head--;
 443                                                 break;
 444                                         }
 445                                         fat[p].head = head;
 446                                 }
 447                         }
 448                         clearchain(boot, fat, h);
 449                         conf |= FSFATMOD;
 450                 }
 451                 ret |= conf;
 452         }
 453
 454         return ret;
 455 }
 456
 457 /*
 458  * Write out FATs encoding them from the internal format
 459  */
 460 int
 461 writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
 462 {
 463         u_char *buffer, *p;
 464         cl_t cl;
 465         int i;
 466         u_int32_t fatsz;
 467         off_t off;
 468         int ret = FSOK;
 469
 470         buffer = malloc(fatsz = boot->FATsecs * boot->BytesPerSec);
 471         if (buffer == NULL) {
 472                 perror("No space for FAT");
 473                 return FSFATAL;
 474         }
 475         memset(buffer, 0, fatsz);
 476         boot->NumFree = 0;
 477         p = buffer;
 478         if (correct_fat) {
 479                 *p++ = (u_char)boot->Media;
 480                 *p++ = 0xff;
 481                 *p++ = 0xff;
 482                 switch (boot->ClustMask) {
 483                 case CLUST16_MASK:
 484                         *p++ = 0xff;
 485                         break;
 486                 case CLUST32_MASK:
 487                         *p++ = 0x0f;
 488                         *p++ = 0xff;
 489                         *p++ = 0xff;
 490                         *p++ = 0xff;
 491                         *p++ = 0x0f;
 492                         break;
 493                 }
 494         } else {
 495                 /* use same FAT signature as the old FAT has */
 496                 int count;
 497                 u_char *old_fat;
 498
 499                 switch (boot->ClustMask) {
 500                 case CLUST32_MASK:
 501                         count = 8;
 502                         break;
 503                 case CLUST16_MASK:
 504                         count = 4;
 505                         break;
 506                 default:
 507                         count = 3;
 508                         break;
 509                 }
 510
 511                 if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
 512                                          &old_fat)) {
 513                         free(buffer);
 514                         return FSFATAL;
 515                 }
 516
 517                 memcpy(p, old_fat, count);
 518                 free(old_fat);
 519                 p += count;
 520         }
 521
 522         for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
 523                 switch (boot->ClustMask) {
 524                 case CLUST32_MASK:
 525                         if (fat[cl].next == CLUST_FREE)
 526                                 boot->NumFree++;
 527                         *p++ = (u_char)fat[cl].next;
 528                         *p++ = (u_char)(fat[cl].next >> 8);
 529                         *p++ = (u_char)(fat[cl].next >> 16);
 530                         *p &= 0xf0;
 531                         *p++ |= (fat[cl].next >> 24)&0x0f;
 532                         break;
 533                 case CLUST16_MASK:
 534                         if (fat[cl].next == CLUST_FREE)
 535                                 boot->NumFree++;
 536                         *p++ = (u_char)fat[cl].next;
 537                         *p++ = (u_char)(fat[cl].next >> 8);
 538                         break;
 539                 default:
 540                         if (fat[cl].next == CLUST_FREE)
 541                                 boot->NumFree++;
 542                         if (cl + 1 < boot->NumClusters
 543                             && fat[cl + 1].next == CLUST_FREE)
 544                                 boot->NumFree++;
 545                         *p++ = (u_char)fat[cl].next;
 546                         *p++ = (u_char)((fat[cl].next >> 8) & 0xf)
 547                                |(u_char)(fat[cl+1].next << 4);
 548                         *p++ = (u_char)(fat[++cl].next >> 4);
 549                         break;
 550                 }
 551         }
 552         for (i = 0; i < boot->FATs; i++) {
 553                 off = boot->ResSectors + i * boot->FATsecs;
 554                 off *= boot->BytesPerSec;
 555                 if (lseek(fs, off, SEEK_SET) != off
 556                     || write(fs, buffer, fatsz) != fatsz) {
 557                         perror("Unable to write FAT");
 558                         ret = FSFATAL; /* Return immediately?           XXX */
 559                 }
 560         }
 561         free(buffer);
 562         return ret;
 563 }
 564
 565 /*
 566  * Check a complete in-memory FAT for lost cluster chains
 567  */
 568 int
 569 checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
 570 {
 571         cl_t head;
 572         int mod = FSOK;
 573         int ret;
 574
 575         for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
 576                 /* find next untravelled chain */
 577                 if (fat[head].head != head
 578                     || fat[head].next == CLUST_FREE
 579                     || (fat[head].next >= CLUST_RSRVD
 580                         && fat[head].next < CLUST_EOFS)
 581                     || (fat[head].flags & FAT_USED))
 582                         continue;
 583
 584                 pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
 585                       head, fat[head].length);
 586                 mod |= ret = reconnect(dosfs, boot, fat, head);
 587                 if (mod & FSFATAL)
 588                         break;
 589                 if (ret == FSERROR && ask(0, "Clear")) {
 590                         clearchain(boot, fat, head);
 591                         mod |= FSFATMOD;
 592                 }
 593         }
 594         finishlf();
 595
 596         if (boot->FSInfo) {
 597                 ret = 0;
 598                 if (boot->FSFree != boot->NumFree) {
 599                         pwarn("Free space in FSInfo block (%d) not correct (%d)\n",
 600                               boot->FSFree, boot->NumFree);
 601                         if (ask(1, "fix")) {
 602                                 boot->FSFree = boot->NumFree;
 603                                 ret = 1;
 604                         }
 605                 }
 606                 if (boot->NumFree && (boot->FSNext >= boot->NumClusters ||
 607                                       fat[boot->FSNext].next != CLUST_FREE)) {
 608                         pwarn("Next free cluster in FSInfo block (%u) not free\n",
 609                               boot->FSNext);
 610                         if (ask(1, "fix"))
 611                                 for (head = CLUST_FIRST; head < boot->NumClusters; head++)
 612                                         if (fat[head].next == CLUST_FREE) {
 613                                                 boot->FSNext = head;
 614                                                 ret = 1;
 615                                                 break;
 616                                         }
 617                 }
 618                 if (ret)
 619                         mod |= writefsinfo(dosfs, boot);
 620         }
 621
 622         return mod;
 623 }