55int
56checkdirty(int fs, struct bootblock *boot)
57{
58 off_t off;
59 u_char *buffer;
60 int ret = 0;
61
62 if (boot->ClustMask == CLUST12_MASK)
63 return 0;
64
65 off = boot->ResSectors;
66 off *= boot->BytesPerSec;
67
68 buffer = malloc(boot->BytesPerSec);
69 if (buffer == NULL) {
70 perror("No space for FAT");
71 return 1;
72 }
73
74 if (lseek(fs, off, SEEK_SET) != off) {
75 perror("Unable to read FAT");
76 goto err;
77 }
78
79 if (read(fs, buffer, boot->BytesPerSec) != boot->BytesPerSec) {
80 perror("Unable to read FAT");
81 goto err;
82 }
83
84 if (buffer[0] == boot->Media && buffer[1] == 0xff && buffer[2] == 0xff
85 && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
86 || (boot->ClustMask == CLUST32_MASK && buffer[3] == 0x0f
87 && buffer[4] == 0xff && buffer[5] == 0xff
88 && buffer[6] == 0xff && buffer[7] == 0x07)))
89 ret = 0;
90 else
91 ret = 1;
92
93err:
94 free(buffer);
95 return ret;
96}
97
98/*
99 * Check a cluster number for valid value
100 */
101static int
102checkclnum(struct bootblock *boot, int fat, cl_t cl, cl_t *next)
103{
104 if (*next >= (CLUST_RSRVD&boot->ClustMask))
105 *next |= ~boot->ClustMask;
106 if (*next == CLUST_FREE) {
107 boot->NumFree++;
108 return FSOK;
109 }
110 if (*next == CLUST_BAD) {
111 boot->NumBad++;
112 return FSOK;
113 }
114 if (*next < CLUST_FIRST
115 || (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
116 pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
117 cl, fat,
118 *next < CLUST_RSRVD ? "out of range" : "reserved",
119 *next&boot->ClustMask);
120 if (ask(0, "Truncate")) {
121 *next = CLUST_EOF;
122 return FSFATMOD;
123 }
124 return FSERROR;
125 }
126 return FSOK;
127}
128
129/*
130 * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
131 */
132static int
133_readfat(int fs, struct bootblock *boot, int no, u_char **buffer)
134{
135 off_t off;
136
137 *buffer = malloc(boot->FATsecs * boot->BytesPerSec);
138 if (*buffer == NULL) {
139 perror("No space for FAT");
140 return 0;
141 }
142
143 off = boot->ResSectors + no * boot->FATsecs;
144 off *= boot->BytesPerSec;
145
146 if (lseek(fs, off, SEEK_SET) != off) {
147 perror("Unable to read FAT");
148 goto err;
149 }
150
151 if (read(fs, *buffer, boot->FATsecs * boot->BytesPerSec)
152 != boot->FATsecs * boot->BytesPerSec) {
153 perror("Unable to read FAT");
154 goto err;
155 }
156
157 return 1;
158
159 err:
160 free(*buffer);
161 return 0;
162}
163
164/*
165 * Read a FAT and decode it into internal format
166 */
167int
168readfat(int fs, struct bootblock *boot, int no, struct fatEntry **fp)
169{
170 struct fatEntry *fat;
171 u_char *buffer, *p;
172 cl_t cl;
173 int ret = FSOK;
174
175 boot->NumFree = boot->NumBad = 0;
176
177 if (!_readfat(fs, boot, no, &buffer))
178 return FSFATAL;
179
180 fat = calloc(boot->NumClusters, sizeof(struct fatEntry));
181 if (fat == NULL) {
182 perror("No space for FAT");
183 free(buffer);
184 return FSFATAL;
185 }
186
187 if (buffer[0] != boot->Media
188 || buffer[1] != 0xff || buffer[2] != 0xff
189 || (boot->ClustMask == CLUST16_MASK && buffer[3] != 0xff)
190 || (boot->ClustMask == CLUST32_MASK
191 && ((buffer[3]&0x0f) != 0x0f
192 || buffer[4] != 0xff || buffer[5] != 0xff
193 || buffer[6] != 0xff || (buffer[7]&0x0f) != 0x0f))) {
194
195 /* Windows 95 OSR2 (and possibly any later) changes
196 * the FAT signature to 0xXXffff7f for FAT16 and to
197 * 0xXXffff0fffffff07 for FAT32 upon boot, to know that the
198 * file system is dirty if it doesn't reboot cleanly.
199 * Check this special condition before errorring out.
200 */
201 if (buffer[0] == boot->Media && buffer[1] == 0xff
202 && buffer[2] == 0xff
203 && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
204 || (boot->ClustMask == CLUST32_MASK
205 && buffer[3] == 0x0f && buffer[4] == 0xff
206 && buffer[5] == 0xff && buffer[6] == 0xff
207 && buffer[7] == 0x07)))
208 ret |= FSDIRTY;
209 else {
210 /* just some odd byte sequence in FAT */
211
212 switch (boot->ClustMask) {
213 case CLUST32_MASK:
214 pwarn("%s (%02x%02x%02x%02x%02x%02x%02x%02x)\n",
215 "FAT starts with odd byte sequence",
216 buffer[0], buffer[1], buffer[2], buffer[3],
217 buffer[4], buffer[5], buffer[6], buffer[7]);
218 break;
219 case CLUST16_MASK:
220 pwarn("%s (%02x%02x%02x%02x)\n",
221 "FAT starts with odd byte sequence",
222 buffer[0], buffer[1], buffer[2], buffer[3]);
223 break;
224 default:
225 pwarn("%s (%02x%02x%02x)\n",
226 "FAT starts with odd byte sequence",
227 buffer[0], buffer[1], buffer[2]);
228 break;
229 }
230
231
232 if (ask(1, "Correct"))
233 ret |= FSFIXFAT;
234 }
235 }
236 switch (boot->ClustMask) {
237 case CLUST32_MASK:
238 p = buffer + 8;
239 break;
240 case CLUST16_MASK:
241 p = buffer + 4;
242 break;
243 default:
244 p = buffer + 3;
245 break;
246 }
247 for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
248 switch (boot->ClustMask) {
249 case CLUST32_MASK:
250 fat[cl].next = p[0] + (p[1] << 8)
251 + (p[2] << 16) + (p[3] << 24);
252 fat[cl].next &= boot->ClustMask;
253 ret |= checkclnum(boot, no, cl, &fat[cl].next);
254 cl++;
255 p += 4;
256 break;
257 case CLUST16_MASK:
258 fat[cl].next = p[0] + (p[1] << 8);
259 ret |= checkclnum(boot, no, cl, &fat[cl].next);
260 cl++;
261 p += 2;
262 break;
263 default:
264 fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
265 ret |= checkclnum(boot, no, cl, &fat[cl].next);
266 cl++;
267 if (cl >= boot->NumClusters)
268 break;
269 fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
270 ret |= checkclnum(boot, no, cl, &fat[cl].next);
271 cl++;
272 p += 3;
273 break;
274 }
275 }
276
277 free(buffer);
278 *fp = fat;
279 return ret;
280}
281
282/*
283 * Get type of reserved cluster
284 */
285char *
286rsrvdcltype(cl_t cl)
287{
288 if (cl == CLUST_FREE)
289 return "free";
290 if (cl < CLUST_BAD)
291 return "reserved";
292 if (cl > CLUST_BAD)
293 return "as EOF";
294 return "bad";
295}
296
297static int
298clustdiffer(cl_t cl, cl_t *cp1, cl_t *cp2, int fatnum)
299{
300 if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
301 if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
302 if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
303 && *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
304 || (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
305 pwarn("Cluster %u is marked %s with different indicators, ",
306 cl, rsrvdcltype(*cp1));
307 if (ask(1, "fix")) {
308 *cp2 = *cp1;
309 return FSFATMOD;
310 }
311 return FSFATAL;
312 }
313 pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %d\n",
314 cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
315 if (ask(0, "use FAT 0's entry")) {
316 *cp2 = *cp1;
317 return FSFATMOD;
318 }
319 if (ask(0, "use FAT %d's entry", fatnum)) {
320 *cp1 = *cp2;
321 return FSFATMOD;
322 }
323 return FSFATAL;
324 }
325 pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
326 cl, rsrvdcltype(*cp1), *cp2, fatnum);
327 if (ask(0, "Use continuation from FAT %d", fatnum)) {
328 *cp1 = *cp2;
329 return FSFATMOD;
330 }
331 if (ask(0, "Use mark from FAT 0")) {
332 *cp2 = *cp1;
333 return FSFATMOD;
334 }
335 return FSFATAL;
336 }
337 if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
338 pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %d\n",
339 cl, *cp1, rsrvdcltype(*cp2), fatnum);
340 if (ask(0, "Use continuation from FAT 0")) {
341 *cp2 = *cp1;
342 return FSFATMOD;
343 }
344 if (ask(0, "Use mark from FAT %d", fatnum)) {
345 *cp1 = *cp2;
346 return FSFATMOD;
347 }
348 return FSERROR;
349 }
350 pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %d\n",
351 cl, *cp1, *cp2, fatnum);
352 if (ask(0, "Use continuation from FAT 0")) {
353 *cp2 = *cp1;
354 return FSFATMOD;
355 }
356 if (ask(0, "Use continuation from FAT %d", fatnum)) {
357 *cp1 = *cp2;
358 return FSFATMOD;
359 }
360 return FSERROR;
361}
362
363/*
364 * Compare two FAT copies in memory. Resolve any conflicts and merge them
365 * into the first one.
366 */
367int
368comparefat(struct bootblock *boot, struct fatEntry *first,
369 struct fatEntry *second, int fatnum)
370{
371 cl_t cl;
372 int ret = FSOK;
373
374 for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
375 if (first[cl].next != second[cl].next)
376 ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
377 return ret;
378}
379
380void
381clearchain(struct bootblock *boot, struct fatEntry *fat, cl_t head)
382{
383 cl_t p, q;
384
385 for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
386 if (fat[p].head != head)
387 break;
388 q = fat[p].next;
389 fat[p].next = fat[p].head = CLUST_FREE;
390 fat[p].length = 0;
391 }
392}
393
394int
395tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *trunc)
396{
397 if (ask(0, "Clear chain starting at %u", head)) {
398 clearchain(boot, fat, head);
399 return FSFATMOD;
400 } else if (ask(0, "Truncate")) {
401 *trunc = CLUST_EOF;
402 return FSFATMOD;
403 } else
404 return FSERROR;
405}
406
407/*
408 * Check a complete FAT in-memory for crosslinks
409 */
410int
411checkfat(struct bootblock *boot, struct fatEntry *fat)
412{
413 cl_t head, p, h, n;
414 u_int len;
415 int ret = 0;
416 int conf;
417
418 /*
419 * pass 1: figure out the cluster chains.
420 */
421 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
422 /* find next untravelled chain */
423 if (fat[head].head != 0 /* cluster already belongs to some chain */
424 || fat[head].next == CLUST_FREE
425 || fat[head].next == CLUST_BAD)
426 continue; /* skip it. */
427
428 /* follow the chain and mark all clusters on the way */
429 for (len = 0, p = head;
430 p >= CLUST_FIRST && p < boot->NumClusters;
431 p = fat[p].next) {
432 fat[p].head = head;
433 len++;
434 }
435
436 /* the head record gets the length */
437 fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
438 }
439
440 /*
441 * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
442 * we didn't know the real start of the chain then - would have treated partial
443 * chains as interlinked with their main chain)
444 */
445 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
446 /* find next untravelled chain */
447 if (fat[head].head != head)
448 continue;
449
450 /* follow the chain to its end (hopefully) */
451 for (p = head;
452 (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
453 p = n)
454 if (fat[n].head != head)
455 break;
456 if (n >= CLUST_EOFS)
457 continue;
458
459 if (n == CLUST_FREE || n >= CLUST_RSRVD) {
460 pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
461 head, rsrvdcltype(n));
462 ret |= tryclear(boot, fat, head, &fat[p].next);
463 continue;
464 }
465 if (n < CLUST_FIRST || n >= boot->NumClusters) {
466 pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
467 head, n);
468 ret |= tryclear(boot, fat, head, &fat[p].next);
469 continue;
470 }
471 pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
472 head, fat[n].head, n);
473 conf = tryclear(boot, fat, head, &fat[p].next);
474 if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
475 if (conf == FSERROR) {
476 /*
477 * Transfer the common chain to the one not cleared above.
478 */
479 for (p = n;
480 p >= CLUST_FIRST && p < boot->NumClusters;
481 p = fat[p].next) {
482 if (h != fat[p].head) {
483 /*
484 * Have to reexamine this chain.
485 */
486 head--;
487 break;
488 }
489 fat[p].head = head;
490 }
491 }
492 clearchain(boot, fat, h);
493 conf |= FSFATMOD;
494 }
495 ret |= conf;
496 }
497
498 return ret;
499}
500
501/*
502 * Write out FATs encoding them from the internal format
503 */
504int
505writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
506{
507 u_char *buffer, *p;
508 cl_t cl;
509 int i;
510 u_int32_t fatsz;
511 off_t off;
512 int ret = FSOK;
513
514 buffer = malloc(fatsz = boot->FATsecs * boot->BytesPerSec);
515 if (buffer == NULL) {
516 perror("No space for FAT");
517 return FSFATAL;
518 }
519 memset(buffer, 0, fatsz);
520 boot->NumFree = 0;
521 p = buffer;
522 if (correct_fat) {
523 *p++ = (u_char)boot->Media;
524 *p++ = 0xff;
525 *p++ = 0xff;
526 switch (boot->ClustMask) {
527 case CLUST16_MASK:
528 *p++ = 0xff;
529 break;
530 case CLUST32_MASK:
531 *p++ = 0x0f;
532 *p++ = 0xff;
533 *p++ = 0xff;
534 *p++ = 0xff;
535 *p++ = 0x0f;
536 break;
537 }
538 } else {
539 /* use same FAT signature as the old FAT has */
540 int count;
541 u_char *old_fat;
542
543 switch (boot->ClustMask) {
544 case CLUST32_MASK:
545 count = 8;
546 break;
547 case CLUST16_MASK:
548 count = 4;
549 break;
550 default:
551 count = 3;
552 break;
553 }
554
555 if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
556 &old_fat)) {
557 free(buffer);
558 return FSFATAL;
559 }
560
561 memcpy(p, old_fat, count);
562 free(old_fat);
563 p += count;
564 }
565
566 for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
567 switch (boot->ClustMask) {
568 case CLUST32_MASK:
569 if (fat[cl].next == CLUST_FREE)
570 boot->NumFree++;
571 *p++ = (u_char)fat[cl].next;
572 *p++ = (u_char)(fat[cl].next >> 8);
573 *p++ = (u_char)(fat[cl].next >> 16);
574 *p &= 0xf0;
575 *p++ |= (fat[cl].next >> 24)&0x0f;
576 break;
577 case CLUST16_MASK:
578 if (fat[cl].next == CLUST_FREE)
579 boot->NumFree++;
580 *p++ = (u_char)fat[cl].next;
581 *p++ = (u_char)(fat[cl].next >> 8);
582 break;
583 default:
584 if (fat[cl].next == CLUST_FREE)
585 boot->NumFree++;
586 if (cl + 1 < boot->NumClusters
587 && fat[cl + 1].next == CLUST_FREE)
588 boot->NumFree++;
589 *p++ = (u_char)fat[cl].next;
590 *p++ = (u_char)((fat[cl].next >> 8) & 0xf)
591 |(u_char)(fat[cl+1].next << 4);
592 *p++ = (u_char)(fat[++cl].next >> 4);
593 break;
594 }
595 }
596 for (i = 0; i < boot->FATs; i++) {
597 off = boot->ResSectors + i * boot->FATsecs;
598 off *= boot->BytesPerSec;
599 if (lseek(fs, off, SEEK_SET) != off
600 || write(fs, buffer, fatsz) != fatsz) {
601 perror("Unable to write FAT");
602 ret = FSFATAL; /* Return immediately? XXX */
603 }
604 }
605 free(buffer);
606 return ret;
607}
608
609/*
610 * Check a complete in-memory FAT for lost cluster chains
611 */
612int
613checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
614{
615 cl_t head;
616 int mod = FSOK;
617 int ret;
618
619 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
620 /* find next untravelled chain */
621 if (fat[head].head != head
622 || fat[head].next == CLUST_FREE
623 || (fat[head].next >= CLUST_RSRVD
624 && fat[head].next < CLUST_EOFS)
625 || (fat[head].flags & FAT_USED))
626 continue;
627
628 pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
629 head, fat[head].length);
630 mod |= ret = reconnect(dosfs, boot, fat, head);
631 if (mod & FSFATAL)
632 break;
633 if (ret == FSERROR && ask(0, "Clear")) {
634 clearchain(boot, fat, head);
635 mod |= FSFATMOD;
636 }
637 }
638 finishlf();
639
640 if (boot->FSInfo) {
641 ret = 0;
642 if (boot->FSFree != boot->NumFree) {
643 pwarn("Free space in FSInfo block (%d) not correct (%d)\n",
644 boot->FSFree, boot->NumFree);
645 if (ask(1, "fix")) {
646 boot->FSFree = boot->NumFree;
647 ret = 1;
648 }
649 }
650 if (boot->NumFree && fat[boot->FSNext].next != CLUST_FREE) {
651 pwarn("Next free cluster in FSInfo block (%u) not free\n",
652 boot->FSNext);
653 if (ask(1, "fix"))
654 for (head = CLUST_FIRST; head < boot->NumClusters; head++)
655 if (fat[head].next == CLUST_FREE) {
656 boot->FSNext = head;
657 ret = 1;
658 break;
659 }
660 }
661 if (ret)
662 mod |= writefsinfo(dosfs, boot);
663 }
664
665 return mod;
666}
| 73int
74checkdirty(int fs, struct bootblock *boot)
75{
76 off_t off;
77 u_char *buffer;
78 int ret = 0;
79
80 if (boot->ClustMask == CLUST12_MASK)
81 return 0;
82
83 off = boot->ResSectors;
84 off *= boot->BytesPerSec;
85
86 buffer = malloc(boot->BytesPerSec);
87 if (buffer == NULL) {
88 perror("No space for FAT");
89 return 1;
90 }
91
92 if (lseek(fs, off, SEEK_SET) != off) {
93 perror("Unable to read FAT");
94 goto err;
95 }
96
97 if (read(fs, buffer, boot->BytesPerSec) != boot->BytesPerSec) {
98 perror("Unable to read FAT");
99 goto err;
100 }
101
102 if (buffer[0] == boot->Media && buffer[1] == 0xff && buffer[2] == 0xff
103 && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
104 || (boot->ClustMask == CLUST32_MASK && buffer[3] == 0x0f
105 && buffer[4] == 0xff && buffer[5] == 0xff
106 && buffer[6] == 0xff && buffer[7] == 0x07)))
107 ret = 0;
108 else
109 ret = 1;
110
111err:
112 free(buffer);
113 return ret;
114}
115
116/*
117 * Check a cluster number for valid value
118 */
119static int
120checkclnum(struct bootblock *boot, int fat, cl_t cl, cl_t *next)
121{
122 if (*next >= (CLUST_RSRVD&boot->ClustMask))
123 *next |= ~boot->ClustMask;
124 if (*next == CLUST_FREE) {
125 boot->NumFree++;
126 return FSOK;
127 }
128 if (*next == CLUST_BAD) {
129 boot->NumBad++;
130 return FSOK;
131 }
132 if (*next < CLUST_FIRST
133 || (*next >= boot->NumClusters && *next < CLUST_EOFS)) {
134 pwarn("Cluster %u in FAT %d continues with %s cluster number %u\n",
135 cl, fat,
136 *next < CLUST_RSRVD ? "out of range" : "reserved",
137 *next&boot->ClustMask);
138 if (ask(0, "Truncate")) {
139 *next = CLUST_EOF;
140 return FSFATMOD;
141 }
142 return FSERROR;
143 }
144 return FSOK;
145}
146
147/*
148 * Read a FAT from disk. Returns 1 if successful, 0 otherwise.
149 */
150static int
151_readfat(int fs, struct bootblock *boot, int no, u_char **buffer)
152{
153 off_t off;
154
155 *buffer = malloc(boot->FATsecs * boot->BytesPerSec);
156 if (*buffer == NULL) {
157 perror("No space for FAT");
158 return 0;
159 }
160
161 off = boot->ResSectors + no * boot->FATsecs;
162 off *= boot->BytesPerSec;
163
164 if (lseek(fs, off, SEEK_SET) != off) {
165 perror("Unable to read FAT");
166 goto err;
167 }
168
169 if (read(fs, *buffer, boot->FATsecs * boot->BytesPerSec)
170 != boot->FATsecs * boot->BytesPerSec) {
171 perror("Unable to read FAT");
172 goto err;
173 }
174
175 return 1;
176
177 err:
178 free(*buffer);
179 return 0;
180}
181
182/*
183 * Read a FAT and decode it into internal format
184 */
185int
186readfat(int fs, struct bootblock *boot, int no, struct fatEntry **fp)
187{
188 struct fatEntry *fat;
189 u_char *buffer, *p;
190 cl_t cl;
191 int ret = FSOK;
192
193 boot->NumFree = boot->NumBad = 0;
194
195 if (!_readfat(fs, boot, no, &buffer))
196 return FSFATAL;
197
198 fat = calloc(boot->NumClusters, sizeof(struct fatEntry));
199 if (fat == NULL) {
200 perror("No space for FAT");
201 free(buffer);
202 return FSFATAL;
203 }
204
205 if (buffer[0] != boot->Media
206 || buffer[1] != 0xff || buffer[2] != 0xff
207 || (boot->ClustMask == CLUST16_MASK && buffer[3] != 0xff)
208 || (boot->ClustMask == CLUST32_MASK
209 && ((buffer[3]&0x0f) != 0x0f
210 || buffer[4] != 0xff || buffer[5] != 0xff
211 || buffer[6] != 0xff || (buffer[7]&0x0f) != 0x0f))) {
212
213 /* Windows 95 OSR2 (and possibly any later) changes
214 * the FAT signature to 0xXXffff7f for FAT16 and to
215 * 0xXXffff0fffffff07 for FAT32 upon boot, to know that the
216 * file system is dirty if it doesn't reboot cleanly.
217 * Check this special condition before errorring out.
218 */
219 if (buffer[0] == boot->Media && buffer[1] == 0xff
220 && buffer[2] == 0xff
221 && ((boot->ClustMask == CLUST16_MASK && buffer[3] == 0x7f)
222 || (boot->ClustMask == CLUST32_MASK
223 && buffer[3] == 0x0f && buffer[4] == 0xff
224 && buffer[5] == 0xff && buffer[6] == 0xff
225 && buffer[7] == 0x07)))
226 ret |= FSDIRTY;
227 else {
228 /* just some odd byte sequence in FAT */
229
230 switch (boot->ClustMask) {
231 case CLUST32_MASK:
232 pwarn("%s (%02x%02x%02x%02x%02x%02x%02x%02x)\n",
233 "FAT starts with odd byte sequence",
234 buffer[0], buffer[1], buffer[2], buffer[3],
235 buffer[4], buffer[5], buffer[6], buffer[7]);
236 break;
237 case CLUST16_MASK:
238 pwarn("%s (%02x%02x%02x%02x)\n",
239 "FAT starts with odd byte sequence",
240 buffer[0], buffer[1], buffer[2], buffer[3]);
241 break;
242 default:
243 pwarn("%s (%02x%02x%02x)\n",
244 "FAT starts with odd byte sequence",
245 buffer[0], buffer[1], buffer[2]);
246 break;
247 }
248
249
250 if (ask(1, "Correct"))
251 ret |= FSFIXFAT;
252 }
253 }
254 switch (boot->ClustMask) {
255 case CLUST32_MASK:
256 p = buffer + 8;
257 break;
258 case CLUST16_MASK:
259 p = buffer + 4;
260 break;
261 default:
262 p = buffer + 3;
263 break;
264 }
265 for (cl = CLUST_FIRST; cl < boot->NumClusters;) {
266 switch (boot->ClustMask) {
267 case CLUST32_MASK:
268 fat[cl].next = p[0] + (p[1] << 8)
269 + (p[2] << 16) + (p[3] << 24);
270 fat[cl].next &= boot->ClustMask;
271 ret |= checkclnum(boot, no, cl, &fat[cl].next);
272 cl++;
273 p += 4;
274 break;
275 case CLUST16_MASK:
276 fat[cl].next = p[0] + (p[1] << 8);
277 ret |= checkclnum(boot, no, cl, &fat[cl].next);
278 cl++;
279 p += 2;
280 break;
281 default:
282 fat[cl].next = (p[0] + (p[1] << 8)) & 0x0fff;
283 ret |= checkclnum(boot, no, cl, &fat[cl].next);
284 cl++;
285 if (cl >= boot->NumClusters)
286 break;
287 fat[cl].next = ((p[1] >> 4) + (p[2] << 4)) & 0x0fff;
288 ret |= checkclnum(boot, no, cl, &fat[cl].next);
289 cl++;
290 p += 3;
291 break;
292 }
293 }
294
295 free(buffer);
296 *fp = fat;
297 return ret;
298}
299
300/*
301 * Get type of reserved cluster
302 */
303char *
304rsrvdcltype(cl_t cl)
305{
306 if (cl == CLUST_FREE)
307 return "free";
308 if (cl < CLUST_BAD)
309 return "reserved";
310 if (cl > CLUST_BAD)
311 return "as EOF";
312 return "bad";
313}
314
315static int
316clustdiffer(cl_t cl, cl_t *cp1, cl_t *cp2, int fatnum)
317{
318 if (*cp1 == CLUST_FREE || *cp1 >= CLUST_RSRVD) {
319 if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
320 if ((*cp1 != CLUST_FREE && *cp1 < CLUST_BAD
321 && *cp2 != CLUST_FREE && *cp2 < CLUST_BAD)
322 || (*cp1 > CLUST_BAD && *cp2 > CLUST_BAD)) {
323 pwarn("Cluster %u is marked %s with different indicators, ",
324 cl, rsrvdcltype(*cp1));
325 if (ask(1, "fix")) {
326 *cp2 = *cp1;
327 return FSFATMOD;
328 }
329 return FSFATAL;
330 }
331 pwarn("Cluster %u is marked %s in FAT 0, %s in FAT %d\n",
332 cl, rsrvdcltype(*cp1), rsrvdcltype(*cp2), fatnum);
333 if (ask(0, "use FAT 0's entry")) {
334 *cp2 = *cp1;
335 return FSFATMOD;
336 }
337 if (ask(0, "use FAT %d's entry", fatnum)) {
338 *cp1 = *cp2;
339 return FSFATMOD;
340 }
341 return FSFATAL;
342 }
343 pwarn("Cluster %u is marked %s in FAT 0, but continues with cluster %u in FAT %d\n",
344 cl, rsrvdcltype(*cp1), *cp2, fatnum);
345 if (ask(0, "Use continuation from FAT %d", fatnum)) {
346 *cp1 = *cp2;
347 return FSFATMOD;
348 }
349 if (ask(0, "Use mark from FAT 0")) {
350 *cp2 = *cp1;
351 return FSFATMOD;
352 }
353 return FSFATAL;
354 }
355 if (*cp2 == CLUST_FREE || *cp2 >= CLUST_RSRVD) {
356 pwarn("Cluster %u continues with cluster %u in FAT 0, but is marked %s in FAT %d\n",
357 cl, *cp1, rsrvdcltype(*cp2), fatnum);
358 if (ask(0, "Use continuation from FAT 0")) {
359 *cp2 = *cp1;
360 return FSFATMOD;
361 }
362 if (ask(0, "Use mark from FAT %d", fatnum)) {
363 *cp1 = *cp2;
364 return FSFATMOD;
365 }
366 return FSERROR;
367 }
368 pwarn("Cluster %u continues with cluster %u in FAT 0, but with cluster %u in FAT %d\n",
369 cl, *cp1, *cp2, fatnum);
370 if (ask(0, "Use continuation from FAT 0")) {
371 *cp2 = *cp1;
372 return FSFATMOD;
373 }
374 if (ask(0, "Use continuation from FAT %d", fatnum)) {
375 *cp1 = *cp2;
376 return FSFATMOD;
377 }
378 return FSERROR;
379}
380
381/*
382 * Compare two FAT copies in memory. Resolve any conflicts and merge them
383 * into the first one.
384 */
385int
386comparefat(struct bootblock *boot, struct fatEntry *first,
387 struct fatEntry *second, int fatnum)
388{
389 cl_t cl;
390 int ret = FSOK;
391
392 for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++)
393 if (first[cl].next != second[cl].next)
394 ret |= clustdiffer(cl, &first[cl].next, &second[cl].next, fatnum);
395 return ret;
396}
397
398void
399clearchain(struct bootblock *boot, struct fatEntry *fat, cl_t head)
400{
401 cl_t p, q;
402
403 for (p = head; p >= CLUST_FIRST && p < boot->NumClusters; p = q) {
404 if (fat[p].head != head)
405 break;
406 q = fat[p].next;
407 fat[p].next = fat[p].head = CLUST_FREE;
408 fat[p].length = 0;
409 }
410}
411
412int
413tryclear(struct bootblock *boot, struct fatEntry *fat, cl_t head, cl_t *trunc)
414{
415 if (ask(0, "Clear chain starting at %u", head)) {
416 clearchain(boot, fat, head);
417 return FSFATMOD;
418 } else if (ask(0, "Truncate")) {
419 *trunc = CLUST_EOF;
420 return FSFATMOD;
421 } else
422 return FSERROR;
423}
424
425/*
426 * Check a complete FAT in-memory for crosslinks
427 */
428int
429checkfat(struct bootblock *boot, struct fatEntry *fat)
430{
431 cl_t head, p, h, n;
432 u_int len;
433 int ret = 0;
434 int conf;
435
436 /*
437 * pass 1: figure out the cluster chains.
438 */
439 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
440 /* find next untravelled chain */
441 if (fat[head].head != 0 /* cluster already belongs to some chain */
442 || fat[head].next == CLUST_FREE
443 || fat[head].next == CLUST_BAD)
444 continue; /* skip it. */
445
446 /* follow the chain and mark all clusters on the way */
447 for (len = 0, p = head;
448 p >= CLUST_FIRST && p < boot->NumClusters;
449 p = fat[p].next) {
450 fat[p].head = head;
451 len++;
452 }
453
454 /* the head record gets the length */
455 fat[head].length = fat[head].next == CLUST_FREE ? 0 : len;
456 }
457
458 /*
459 * pass 2: check for crosslinked chains (we couldn't do this in pass 1 because
460 * we didn't know the real start of the chain then - would have treated partial
461 * chains as interlinked with their main chain)
462 */
463 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
464 /* find next untravelled chain */
465 if (fat[head].head != head)
466 continue;
467
468 /* follow the chain to its end (hopefully) */
469 for (p = head;
470 (n = fat[p].next) >= CLUST_FIRST && n < boot->NumClusters;
471 p = n)
472 if (fat[n].head != head)
473 break;
474 if (n >= CLUST_EOFS)
475 continue;
476
477 if (n == CLUST_FREE || n >= CLUST_RSRVD) {
478 pwarn("Cluster chain starting at %u ends with cluster marked %s\n",
479 head, rsrvdcltype(n));
480 ret |= tryclear(boot, fat, head, &fat[p].next);
481 continue;
482 }
483 if (n < CLUST_FIRST || n >= boot->NumClusters) {
484 pwarn("Cluster chain starting at %u ends with cluster out of range (%u)\n",
485 head, n);
486 ret |= tryclear(boot, fat, head, &fat[p].next);
487 continue;
488 }
489 pwarn("Cluster chains starting at %u and %u are linked at cluster %u\n",
490 head, fat[n].head, n);
491 conf = tryclear(boot, fat, head, &fat[p].next);
492 if (ask(0, "Clear chain starting at %u", h = fat[n].head)) {
493 if (conf == FSERROR) {
494 /*
495 * Transfer the common chain to the one not cleared above.
496 */
497 for (p = n;
498 p >= CLUST_FIRST && p < boot->NumClusters;
499 p = fat[p].next) {
500 if (h != fat[p].head) {
501 /*
502 * Have to reexamine this chain.
503 */
504 head--;
505 break;
506 }
507 fat[p].head = head;
508 }
509 }
510 clearchain(boot, fat, h);
511 conf |= FSFATMOD;
512 }
513 ret |= conf;
514 }
515
516 return ret;
517}
518
519/*
520 * Write out FATs encoding them from the internal format
521 */
522int
523writefat(int fs, struct bootblock *boot, struct fatEntry *fat, int correct_fat)
524{
525 u_char *buffer, *p;
526 cl_t cl;
527 int i;
528 u_int32_t fatsz;
529 off_t off;
530 int ret = FSOK;
531
532 buffer = malloc(fatsz = boot->FATsecs * boot->BytesPerSec);
533 if (buffer == NULL) {
534 perror("No space for FAT");
535 return FSFATAL;
536 }
537 memset(buffer, 0, fatsz);
538 boot->NumFree = 0;
539 p = buffer;
540 if (correct_fat) {
541 *p++ = (u_char)boot->Media;
542 *p++ = 0xff;
543 *p++ = 0xff;
544 switch (boot->ClustMask) {
545 case CLUST16_MASK:
546 *p++ = 0xff;
547 break;
548 case CLUST32_MASK:
549 *p++ = 0x0f;
550 *p++ = 0xff;
551 *p++ = 0xff;
552 *p++ = 0xff;
553 *p++ = 0x0f;
554 break;
555 }
556 } else {
557 /* use same FAT signature as the old FAT has */
558 int count;
559 u_char *old_fat;
560
561 switch (boot->ClustMask) {
562 case CLUST32_MASK:
563 count = 8;
564 break;
565 case CLUST16_MASK:
566 count = 4;
567 break;
568 default:
569 count = 3;
570 break;
571 }
572
573 if (!_readfat(fs, boot, boot->ValidFat >= 0 ? boot->ValidFat :0,
574 &old_fat)) {
575 free(buffer);
576 return FSFATAL;
577 }
578
579 memcpy(p, old_fat, count);
580 free(old_fat);
581 p += count;
582 }
583
584 for (cl = CLUST_FIRST; cl < boot->NumClusters; cl++) {
585 switch (boot->ClustMask) {
586 case CLUST32_MASK:
587 if (fat[cl].next == CLUST_FREE)
588 boot->NumFree++;
589 *p++ = (u_char)fat[cl].next;
590 *p++ = (u_char)(fat[cl].next >> 8);
591 *p++ = (u_char)(fat[cl].next >> 16);
592 *p &= 0xf0;
593 *p++ |= (fat[cl].next >> 24)&0x0f;
594 break;
595 case CLUST16_MASK:
596 if (fat[cl].next == CLUST_FREE)
597 boot->NumFree++;
598 *p++ = (u_char)fat[cl].next;
599 *p++ = (u_char)(fat[cl].next >> 8);
600 break;
601 default:
602 if (fat[cl].next == CLUST_FREE)
603 boot->NumFree++;
604 if (cl + 1 < boot->NumClusters
605 && fat[cl + 1].next == CLUST_FREE)
606 boot->NumFree++;
607 *p++ = (u_char)fat[cl].next;
608 *p++ = (u_char)((fat[cl].next >> 8) & 0xf)
609 |(u_char)(fat[cl+1].next << 4);
610 *p++ = (u_char)(fat[++cl].next >> 4);
611 break;
612 }
613 }
614 for (i = 0; i < boot->FATs; i++) {
615 off = boot->ResSectors + i * boot->FATsecs;
616 off *= boot->BytesPerSec;
617 if (lseek(fs, off, SEEK_SET) != off
618 || write(fs, buffer, fatsz) != fatsz) {
619 perror("Unable to write FAT");
620 ret = FSFATAL; /* Return immediately? XXX */
621 }
622 }
623 free(buffer);
624 return ret;
625}
626
627/*
628 * Check a complete in-memory FAT for lost cluster chains
629 */
630int
631checklost(int dosfs, struct bootblock *boot, struct fatEntry *fat)
632{
633 cl_t head;
634 int mod = FSOK;
635 int ret;
636
637 for (head = CLUST_FIRST; head < boot->NumClusters; head++) {
638 /* find next untravelled chain */
639 if (fat[head].head != head
640 || fat[head].next == CLUST_FREE
641 || (fat[head].next >= CLUST_RSRVD
642 && fat[head].next < CLUST_EOFS)
643 || (fat[head].flags & FAT_USED))
644 continue;
645
646 pwarn("Lost cluster chain at cluster %u\n%d Cluster(s) lost\n",
647 head, fat[head].length);
648 mod |= ret = reconnect(dosfs, boot, fat, head);
649 if (mod & FSFATAL)
650 break;
651 if (ret == FSERROR && ask(0, "Clear")) {
652 clearchain(boot, fat, head);
653 mod |= FSFATMOD;
654 }
655 }
656 finishlf();
657
658 if (boot->FSInfo) {
659 ret = 0;
660 if (boot->FSFree != boot->NumFree) {
661 pwarn("Free space in FSInfo block (%d) not correct (%d)\n",
662 boot->FSFree, boot->NumFree);
663 if (ask(1, "fix")) {
664 boot->FSFree = boot->NumFree;
665 ret = 1;
666 }
667 }
668 if (boot->NumFree && fat[boot->FSNext].next != CLUST_FREE) {
669 pwarn("Next free cluster in FSInfo block (%u) not free\n",
670 boot->FSNext);
671 if (ask(1, "fix"))
672 for (head = CLUST_FIRST; head < boot->NumClusters; head++)
673 if (fat[head].next == CLUST_FREE) {
674 boot->FSNext = head;
675 ret = 1;
676 break;
677 }
678 }
679 if (ret)
680 mod |= writefsinfo(dosfs, boot);
681 }
682
683 return mod;
684}
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