summaryrefslogtreecommitdiff
path: root/src/check.c
blob: 1ae91c6e7fa19a313ff0b5018d74c679572d8b17 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
/* check.c - Check and repair a PC/MS-DOS file system

   Copyright (C) 1993 Werner Almesberger <werner.almesberger@lrc.di.epfl.ch>
   Copyright (C) 1998 Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de>
   Copyright (C) 2008-2013 Daniel Baumann <mail@daniel-baumann.ch>

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program. If not, see <http://www.gnu.org/licenses/>.

   On Debian systems, the complete text of the GNU General Public License
   can be found in /usr/share/common-licenses/GPL-3 file.
*/

/* FAT32, VFAT, Atari format support, and various fixes additions May 1998
 * by Roman Hodek <Roman.Hodek@informatik.uni-erlangen.de> */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <time.h>

#include "common.h"
#include "dosfsck.h"
#include "io.h"
#include "fat.h"
#include "file.h"
#include "lfn.h"
#include "check.h"

static DOS_FILE *root;

/* get start field of a dir entry */
#define FSTART(p,fs) \
  ((unsigned long)CF_LE_W(p->dir_ent.start) | \
   (fs->fat_bits == 32 ? CF_LE_W(p->dir_ent.starthi) << 16 : 0))

#define MODIFY(p,i,v)					\
  do {							\
    if (p->offset) {					\
	p->dir_ent.i = v;				\
	fs_write(p->offset+offsetof(DIR_ENT,i),		\
		 sizeof(p->dir_ent.i),&p->dir_ent.i);	\
    }							\
  } while(0)

#define MODIFY_START(p,v,fs)						\
  do {									\
    unsigned long __v = (v);						\
    if (!p->offset) {							\
	/* writing to fake entry for FAT32 root dir */			\
	if (!__v) die("Oops, deleting FAT32 root dir!");		\
	fs->root_cluster = __v;						\
	p->dir_ent.start = CT_LE_W(__v&0xffff);				\
	p->dir_ent.starthi = CT_LE_W(__v>>16);				\
	__v = CT_LE_L(__v);						\
	fs_write((loff_t)offsetof(struct boot_sector,root_cluster),	\
	         sizeof(((struct boot_sector *)0)->root_cluster),	\
		 &__v);							\
    }									\
    else {								\
	MODIFY(p,start,CT_LE_W((__v)&0xffff));				\
	if (fs->fat_bits == 32)						\
	    MODIFY(p,starthi,CT_LE_W((__v)>>16));			\
    }									\
  } while(0)

loff_t alloc_rootdir_entry(DOS_FS * fs, DIR_ENT * de, const char *pattern)
{
    static int curr_num = 0;
    loff_t offset;

    if (fs->root_cluster) {
	DIR_ENT d2;
	int i = 0, got = 0;
	unsigned long clu_num, prev = 0;
	loff_t offset2;

	clu_num = fs->root_cluster;
	offset = cluster_start(fs, clu_num);
	while (clu_num > 0 && clu_num != -1) {
	    fs_read(offset, sizeof(DIR_ENT), &d2);
	    if (IS_FREE(d2.name) && d2.attr != VFAT_LN_ATTR) {
		got = 1;
		break;
	    }
	    i += sizeof(DIR_ENT);
	    offset += sizeof(DIR_ENT);
	    if ((i % fs->cluster_size) == 0) {
		prev = clu_num;
		if ((clu_num = next_cluster(fs, clu_num)) == 0 || clu_num == -1)
		    break;
		offset = cluster_start(fs, clu_num);
	    }
	}
	if (!got) {
	    /* no free slot, need to extend root dir: alloc next free cluster
	     * after previous one */
	    if (!prev)
		die("Root directory has no cluster allocated!");
	    for (clu_num = prev + 1; clu_num != prev; clu_num++) {
		FAT_ENTRY entry;

		if (clu_num >= fs->clusters + 2)
		    clu_num = 2;
		get_fat(&entry, fs->fat, clu_num, fs);
		if (!entry.value)
		    break;
	    }
	    if (clu_num == prev)
		die("Root directory full and no free cluster");
	    set_fat(fs, prev, clu_num);
	    set_fat(fs, clu_num, -1);
	    set_owner(fs, clu_num, get_owner(fs, fs->root_cluster));
	    /* clear new cluster */
	    memset(&d2, 0, sizeof(d2));
	    offset = cluster_start(fs, clu_num);
	    for (i = 0; i < fs->cluster_size; i += sizeof(DIR_ENT))
		fs_write(offset + i, sizeof(d2), &d2);
	}
	memset(de, 0, sizeof(DIR_ENT));
	while (1) {
	    char expanded[12];
	    sprintf(expanded, pattern, curr_num);
	    memcpy(de->name, expanded, 8);
	    memcpy(de->ext, expanded + 8, 3);
	    clu_num = fs->root_cluster;
	    i = 0;
	    offset2 = cluster_start(fs, clu_num);
	    while (clu_num > 0 && clu_num != -1) {
		fs_read(offset2, sizeof(DIR_ENT), &d2);
		if (offset2 != offset &&
		    !strncmp((const char *)d2.name, (const char *)de->name,
			     MSDOS_NAME))
		    break;
		i += sizeof(DIR_ENT);
		offset2 += sizeof(DIR_ENT);
		if ((i % fs->cluster_size) == 0) {
		    if ((clu_num = next_cluster(fs, clu_num)) == 0 ||
			clu_num == -1)
			break;
		    offset2 = cluster_start(fs, clu_num);
		}
	    }
	    if (clu_num == 0 || clu_num == -1)
		break;
	    if (++curr_num >= 10000)
		die("Unable to create unique name");
	}
    } else {
	DIR_ENT *root;
	int next_free = 0, scan;

	root = alloc(fs->root_entries * sizeof(DIR_ENT));
	fs_read(fs->root_start, fs->root_entries * sizeof(DIR_ENT), root);

	while (next_free < fs->root_entries)
	    if (IS_FREE(root[next_free].name) &&
		root[next_free].attr != VFAT_LN_ATTR)
		break;
	    else
		next_free++;
	if (next_free == fs->root_entries)
	    die("Root directory is full.");
	offset = fs->root_start + next_free * sizeof(DIR_ENT);
	memset(de, 0, sizeof(DIR_ENT));
	while (1) {
	    char expanded[12];
	    sprintf(expanded, pattern, curr_num);
	    memcpy(de->name, expanded, 8);
	    memcpy(de->ext, expanded + 8, 3);
	    for (scan = 0; scan < fs->root_entries; scan++)
		if (scan != next_free &&
		    !strncmp((const char *)root[scan].name,
			     (const char *)de->name, MSDOS_NAME))
		    break;
	    if (scan == fs->root_entries)
		break;
	    if (++curr_num >= 10000)
		die("Unable to create unique name");
	}
	free(root);
    }
    ++n_files;
    return offset;
}

/**
 * Construct a full path (starting with '/') for the specified dentry,
 * relative to the partition. All components are "long" names where possible.
 *
 * @param[in]   file    Information about dentry (file or directory) of interest
 *
 * return       Pointer to static string containing file's full path
 */
static char *path_name(DOS_FILE * file)
{
    static char path[PATH_MAX * 2];

    if (!file)
	*path = 0;		/* Reached the root directory */
    else {
	if (strlen(path_name(file->parent)) > PATH_MAX)
	    die("Path name too long.");
	if (strcmp(path, "/") != 0)
	    strcat(path, "/");

	/* Append the long name to the path,
	 * or the short name if there isn't a long one
	 */
	strcpy(strrchr(path, 0),
	       file->lfn ? file->lfn : file_name(file->dir_ent.name));
    }
    return path;
}

static int day_n[] =
    { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 0, 0, 0, 0 };
		  /* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */

/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */

time_t date_dos2unix(unsigned short time, unsigned short date)
{
    int month, year;
    time_t secs;

    month = ((date >> 5) & 15) - 1;
    year = date >> 9;
    secs =
	(time & 31) * 2 + 60 * ((time >> 5) & 63) + (time >> 11) * 3600 +
	86400 * ((date & 31) - 1 + day_n[month] + (year / 4) + year * 365 -
		 ((year & 3) == 0 && month < 2 ? 1 : 0) + 3653);
    /* days since 1.1.70 plus 80's leap day */
    return secs;
}

static char *file_stat(DOS_FILE * file)
{
    static char temp[100];
    struct tm *tm;
    char tmp[100];
    time_t date;

    date =
	date_dos2unix(CF_LE_W(file->dir_ent.time), CF_LE_W(file->dir_ent.date));
    tm = localtime(&date);
    strftime(tmp, 99, "%H:%M:%S %b %d %Y", tm);
    sprintf(temp, "  Size %u bytes, date %s", CF_LE_L(file->dir_ent.size), tmp);
    return temp;
}

static int bad_name(DOS_FILE * file)
{
    int i, spc, suspicious = 0;
    char *bad_chars = atari_format ? "*?\\/:" : "*?<>|\"\\/:";
    unsigned char *name = file->dir_ent.name;

    /* Do not complain about (and auto-correct) the extended attribute files
     * of OS/2. */
    if (strncmp((const char *)name, "EA DATA  SF", 11) == 0 ||
	strncmp((const char *)name, "WP ROOT  SF", 11) == 0)
	return 0;

    /* don't complain about the dummy 11 bytes used by patched Linux
       kernels */
    if (file->dir_ent.lcase & FAT_NO_83NAME)
	return 0;

    for (i = 0; i < 8; i++) {
	if (name[i] < ' ' || name[i] == 0x7f)
	    return 1;
	if (name[i] > 0x7f)
	    ++suspicious;
	if (strchr(bad_chars, name[i]))
	    return 1;
    }

    for (i = 8; i < 11; i++) {
	if (name[i] < ' ' || name[i] == 0x7f)
	    return 1;
	if (name[i] > 0x7f)
	    ++suspicious;
	if (strchr(bad_chars, name[i]))
	    return 1;
    }

    spc = 0;
    for (i = 0; i < 8; i++) {
	if (name[i] == ' ')
	    spc = 1;
	else if (spc)
	    /* non-space after a space not allowed, space terminates the name
	     * part */
	    return 1;
    }

    spc = 0;
    for (i = 8; i < 11; i++) {
	if (name[i] == ' ')
	    spc = 1;
	else if (spc)
	    /* non-space after a space not allowed, space terminates the name
	     * part */
	    return 1;
    }

    /* Under GEMDOS, chars >= 128 are never allowed. */
    if (atari_format && suspicious)
	return 1;

    /* Under MS-DOS and Windows, chars >= 128 in short names are valid
     * (but these characters can be visualised differently depending on
     * local codepage: CP437, CP866, etc). The chars are all basically ok,
     * so we shouldn't auto-correct such names. */
    return 0;
}

static void lfn_remove(loff_t from, loff_t to)
{
    DIR_ENT empty;

    /* New dir entry is zeroed except first byte, which is set to 0xe5.
     * This is to avoid that some FAT-reading OSes (not Linux! ;) stop reading
     * a directory at the first zero entry...
     */
    memset(&empty, 0, sizeof(empty));
    empty.name[0] = DELETED_FLAG;

    for (; from < to; from += sizeof(empty)) {
	fs_write(from, sizeof(DIR_ENT), &empty);
    }
}

static void drop_file(DOS_FS * fs, DOS_FILE * file)
{
    unsigned long cluster;

    MODIFY(file, name[0], DELETED_FLAG);
    if (file->lfn)
	lfn_remove(file->lfn_offset, file->offset);
    for (cluster = FSTART(file, fs); cluster > 0 && cluster <
	 fs->clusters + 2; cluster = next_cluster(fs, cluster))
	set_owner(fs, cluster, NULL);
    --n_files;
}

static void truncate_file(DOS_FS * fs, DOS_FILE * file, unsigned long clusters)
{
    int deleting;
    unsigned long walk, next, prev;

    walk = FSTART(file, fs);
    prev = 0;
    if ((deleting = !clusters))
	MODIFY_START(file, 0, fs);
    while (walk > 0 && walk != -1) {
	next = next_cluster(fs, walk);
	if (deleting)
	    set_fat(fs, walk, 0);
	else if ((deleting = !--clusters))
	    set_fat(fs, walk, -1);
	prev = walk;
	walk = next;
    }
}

static void auto_rename(DOS_FILE * file)
{
    DOS_FILE *first, *walk;
    unsigned long int number;

    if (!file->offset)
	return;			/* cannot rename FAT32 root dir */
    first = file->parent ? file->parent->first : root;
    number = 0;
    while (1) {
	char num[8];
	sprintf(num, "%07lu", number);
	memcpy(file->dir_ent.name, "FSCK", 4);
	memcpy(file->dir_ent.name + 4, num, 4);
	memcpy(file->dir_ent.ext, num + 4, 3);
	for (walk = first; walk; walk = walk->next)
	    if (walk != file
		&& !strncmp((const char *)walk->dir_ent.name,
			    (const char *)file->dir_ent.name, MSDOS_NAME))
		break;
	if (!walk) {
	    fs_write(file->offset, MSDOS_NAME, file->dir_ent.name);
	    if (file->lfn)
		lfn_fix_checksum(file->lfn_offset, file->offset,
				 (const char *)file->dir_ent.name);
	    return;
	}
	number++;
	if (number > 9999999) {
	    die("Too many files need repair.");
	}
    }
    die("Can't generate a unique name.");
}

static void rename_file(DOS_FILE * file)
{
    unsigned char name[46];
    unsigned char *walk, *here;

    if (!file->offset) {
	printf("Cannot rename FAT32 root dir\n");
	return;			/* cannot rename FAT32 root dir */
    }
    while (1) {
	printf("New name: ");
	fflush(stdout);
	if (fgets((char *)name, 45, stdin)) {
	    if ((here = (unsigned char *)strchr((const char *)name, '\n')))
		*here = 0;
	    for (walk = (unsigned char *)strrchr((const char *)name, 0);
		 walk >= name && (*walk == ' ' || *walk == '\t'); walk--) ;
	    walk[1] = 0;
	    for (walk = name; *walk == ' ' || *walk == '\t'; walk++) ;
	    if (file_cvt(walk, file->dir_ent.name)) {
		fs_write(file->offset, MSDOS_NAME, file->dir_ent.name);
		if (file->lfn)
		    lfn_fix_checksum(file->lfn_offset, file->offset,
				     (const char *)file->dir_ent.name);
		return;
	    }
	}
    }
}

static int handle_dot(DOS_FS * fs, DOS_FILE * file, int dots)
{
    char *name;

    name =
	strncmp((const char *)file->dir_ent.name, MSDOS_DOT,
		MSDOS_NAME) ? ".." : ".";
    if (!(file->dir_ent.attr & ATTR_DIR)) {
	printf("%s\n  Is a non-directory.\n", path_name(file));
	if (interactive)
	    printf("1) Drop it\n2) Auto-rename\n3) Rename\n"
		   "4) Convert to directory\n");
	else
	    printf("  Auto-renaming it.\n");
	switch (interactive ? get_key("1234", "?") : '2') {
	case '1':
	    drop_file(fs, file);
	    return 1;
	case '2':
	    auto_rename(file);
	    printf("  Renamed to %s\n", file_name(file->dir_ent.name));
	    return 0;
	case '3':
	    rename_file(file);
	    return 0;
	case '4':
	    MODIFY(file, size, CT_LE_L(0));
	    MODIFY(file, attr, file->dir_ent.attr | ATTR_DIR);
	    break;
	}
    }
    if (!dots) {
	printf("Root contains directory \"%s\". Dropping it.\n", name);
	drop_file(fs, file);
	return 1;
    }
    return 0;
}

static int check_file(DOS_FS * fs, DOS_FILE * file)
{
    DOS_FILE *owner;
    int restart;
    unsigned long expect, curr, this, clusters, prev, walk, clusters2;

    if (file->dir_ent.attr & ATTR_DIR) {
	if (CF_LE_L(file->dir_ent.size)) {
	    printf("%s\n  Directory has non-zero size. Fixing it.\n",
		   path_name(file));
	    MODIFY(file, size, CT_LE_L(0));
	}
	if (file->parent
	    && !strncmp((const char *)file->dir_ent.name, MSDOS_DOT,
			MSDOS_NAME)) {
	    expect = FSTART(file->parent, fs);
	    if (FSTART(file, fs) != expect) {
		printf("%s\n  Start (%ld) does not point to parent (%ld)\n",
		       path_name(file), FSTART(file, fs), expect);
		MODIFY_START(file, expect, fs);
	    }
	    return 0;
	}
	if (file->parent
	    && !strncmp((const char *)file->dir_ent.name, MSDOS_DOTDOT,
			MSDOS_NAME)) {
	    expect =
		file->parent->parent ? FSTART(file->parent->parent, fs) : 0;
	    if (fs->root_cluster && expect == fs->root_cluster)
		expect = 0;
	    if (FSTART(file, fs) != expect) {
		printf("%s\n  Start (%lu) does not point to .. (%lu)\n",
		       path_name(file), FSTART(file, fs), expect);
		MODIFY_START(file, expect, fs);
	    }
	    return 0;
	}
	if (FSTART(file, fs) == 0) {
	    printf("%s\n Start does point to root directory. Deleting dir. \n",
		   path_name(file));
	    MODIFY(file, name[0], DELETED_FLAG);
	    return 0;
	}
    }
    if (FSTART(file, fs) >= fs->clusters + 2) {
	printf
	    ("%s\n  Start cluster beyond limit (%lu > %lu). Truncating file.\n",
	     path_name(file), FSTART(file, fs), fs->clusters + 1);
	if (!file->offset)
	    die("Bad FAT32 root directory! (bad start cluster)\n");
	MODIFY_START(file, 0, fs);
    }
    clusters = prev = 0;
    for (curr = FSTART(file, fs) ? FSTART(file, fs) :
	 -1; curr != -1; curr = next_cluster(fs, curr)) {
	FAT_ENTRY curEntry;
	get_fat(&curEntry, fs->fat, curr, fs);

	if (!curEntry.value || bad_cluster(fs, curr)) {
	    printf("%s\n  Contains a %s cluster (%lu). Assuming EOF.\n",
		   path_name(file), curEntry.value ? "bad" : "free", curr);
	    if (prev)
		set_fat(fs, prev, -1);
	    else if (!file->offset)
		die("FAT32 root dir starts with a bad cluster!");
	    else
		MODIFY_START(file, 0, fs);
	    break;
	}
	if (!(file->dir_ent.attr & ATTR_DIR) && CF_LE_L(file->dir_ent.size) <=
	    (unsigned long long)clusters * fs->cluster_size) {
	    printf
		("%s\n  File size is %u bytes, cluster chain length is > %llu "
		 "bytes.\n  Truncating file to %u bytes.\n", path_name(file),
		 CF_LE_L(file->dir_ent.size),
		 (unsigned long long)clusters * fs->cluster_size,
		 CF_LE_L(file->dir_ent.size));
	    truncate_file(fs, file, clusters);
	    break;
	}
	if ((owner = get_owner(fs, curr))) {
	    int do_trunc = 0;
	    printf("%s  and\n", path_name(owner));
	    printf("%s\n  share clusters.\n", path_name(file));
	    clusters2 = 0;
	    for (walk = FSTART(owner, fs); walk > 0 && walk != -1; walk =
		 next_cluster(fs, walk))
		if (walk == curr)
		    break;
		else
		    clusters2++;
	    restart = file->dir_ent.attr & ATTR_DIR;
	    if (!owner->offset) {
		printf("  Truncating second to %llu bytes because first "
		       "is FAT32 root dir.\n",
		       (unsigned long long)clusters2 * fs->cluster_size);
		do_trunc = 2;
	    } else if (!file->offset) {
		printf("  Truncating first to %llu bytes because second "
		       "is FAT32 root dir.\n",
		       (unsigned long long)clusters * fs->cluster_size);
		do_trunc = 1;
	    } else if (interactive)
		printf("1) Truncate first to %llu bytes%s\n"
		       "2) Truncate second to %llu bytes\n",
		       (unsigned long long)clusters * fs->cluster_size,
		       restart ? " and restart" : "",
		       (unsigned long long)clusters2 * fs->cluster_size);
	    else
		printf("  Truncating second to %llu bytes.\n",
		       (unsigned long long)clusters2 * fs->cluster_size);
	    if (do_trunc != 2
		&& (do_trunc == 1
		    || (interactive && get_key("12", "?") == '1'))) {
		prev = 0;
		clusters = 0;
		for (this = FSTART(owner, fs); this > 0 && this != -1; this =
		     next_cluster(fs, this)) {
		    if (this == curr) {
			if (prev)
			    set_fat(fs, prev, -1);
			else
			    MODIFY_START(owner, 0, fs);
			MODIFY(owner, size,
			       CT_LE_L((unsigned long long)clusters *
				       fs->cluster_size));
			if (restart)
			    return 1;
			while (this > 0 && this != -1) {
			    set_owner(fs, this, NULL);
			    this = next_cluster(fs, this);
			}
			this = curr;
			break;
		    }
		    clusters++;
		    prev = this;
		}
		if (this != curr)
		    die("Internal error: didn't find cluster %d in chain"
			" starting at %d", curr, FSTART(owner, fs));
	    } else {
		if (prev)
		    set_fat(fs, prev, -1);
		else
		    MODIFY_START(file, 0, fs);
		break;
	    }
	}
	set_owner(fs, curr, file);
	clusters++;
	prev = curr;
    }
    if (!(file->dir_ent.attr & ATTR_DIR) && CF_LE_L(file->dir_ent.size) >
	(unsigned long long)clusters * fs->cluster_size) {
	printf
	    ("%s\n  File size is %u bytes, cluster chain length is %llu bytes."
	     "\n  Truncating file to %llu bytes.\n", path_name(file),
	     CF_LE_L(file->dir_ent.size),
	     (unsigned long long)clusters * fs->cluster_size,
	     (unsigned long long)clusters * fs->cluster_size);
	MODIFY(file, size,
	       CT_LE_L((unsigned long long)clusters * fs->cluster_size));
    }
    return 0;
}

static int check_files(DOS_FS * fs, DOS_FILE * start)
{
    while (start) {
	if (check_file(fs, start))
	    return 1;
	start = start->next;
    }
    return 0;
}

static int check_dir(DOS_FS * fs, DOS_FILE ** root, int dots)
{
    DOS_FILE *parent, **walk, **scan;
    int dot, dotdot, skip, redo;
    int good, bad;

    if (!*root)
	return 0;
    parent = (*root)->parent;
    good = bad = 0;
    for (walk = root; *walk; walk = &(*walk)->next)
	if (bad_name(*walk))
	    bad++;
	else
	    good++;
    if (*root && parent && good + bad > 4 && bad > good / 2) {
	printf("%s\n  Has a large number of bad entries. (%d/%d)\n",
	       path_name(parent), bad, good + bad);
	if (!dots)
	    printf("  Not dropping root directory.\n");
	else if (!interactive)
	    printf("  Not dropping it in auto-mode.\n");
	else if (get_key("yn", "Drop directory ? (y/n)") == 'y') {
	    truncate_file(fs, parent, 0);
	    MODIFY(parent, name[0], DELETED_FLAG);
	    /* buglet: deleted directory stays in the list. */
	    return 1;
	}
    }
    dot = dotdot = redo = 0;
    walk = root;
    while (*walk) {
	if (!strncmp
	    ((const char *)((*walk)->dir_ent.name), MSDOS_DOT, MSDOS_NAME)
	    || !strncmp((const char *)((*walk)->dir_ent.name), MSDOS_DOTDOT,
			MSDOS_NAME)) {
	    if (handle_dot(fs, *walk, dots)) {
		*walk = (*walk)->next;
		continue;
	    }
	    if (!strncmp
		((const char *)((*walk)->dir_ent.name), MSDOS_DOT, MSDOS_NAME))
		dot++;
	    else
		dotdot++;
	}
	if (!((*walk)->dir_ent.attr & ATTR_VOLUME) && bad_name(*walk)) {
	    puts(path_name(*walk));
	    printf("  Bad short file name (%s).\n",
		   file_name((*walk)->dir_ent.name));
	    if (interactive)
		printf("1) Drop file\n2) Rename file\n3) Auto-rename\n"
		       "4) Keep it\n");
	    else
		printf("  Auto-renaming it.\n");
	    switch (interactive ? get_key("1234", "?") : '3') {
	    case '1':
		drop_file(fs, *walk);
		walk = &(*walk)->next;
		continue;
	    case '2':
		rename_file(*walk);
		redo = 1;
		break;
	    case '3':
		auto_rename(*walk);
		printf("  Renamed to %s\n", file_name((*walk)->dir_ent.name));
		break;
	    case '4':
		break;
	    }
	}
	/* don't check for duplicates of the volume label */
	if (!((*walk)->dir_ent.attr & ATTR_VOLUME)) {
	    scan = &(*walk)->next;
	    skip = 0;
	    while (*scan && !skip) {
		if (!((*scan)->dir_ent.attr & ATTR_VOLUME) &&
		    !memcmp((*walk)->dir_ent.name, (*scan)->dir_ent.name,
			    MSDOS_NAME)) {
		    printf("%s\n  Duplicate directory entry.\n  First  %s\n",
			   path_name(*walk), file_stat(*walk));
		    printf("  Second %s\n", file_stat(*scan));
		    if (interactive)
			printf
			    ("1) Drop first\n2) Drop second\n3) Rename first\n"
			     "4) Rename second\n5) Auto-rename first\n"
			     "6) Auto-rename second\n");
		    else
			printf("  Auto-renaming second.\n");
		    switch (interactive ? get_key("123456", "?") : '6') {
		    case '1':
			drop_file(fs, *walk);
			*walk = (*walk)->next;
			skip = 1;
			break;
		    case '2':
			drop_file(fs, *scan);
			*scan = (*scan)->next;
			continue;
		    case '3':
			rename_file(*walk);
			printf("  Renamed to %s\n", path_name(*walk));
			redo = 1;
			break;
		    case '4':
			rename_file(*scan);
			printf("  Renamed to %s\n", path_name(*walk));
			redo = 1;
			break;
		    case '5':
			auto_rename(*walk);
			printf("  Renamed to %s\n",
			       file_name((*walk)->dir_ent.name));
			break;
		    case '6':
			auto_rename(*scan);
			printf("  Renamed to %s\n",
			       file_name((*scan)->dir_ent.name));
			break;
		    }
		}
		scan = &(*scan)->next;
	    }
	    if (skip)
		continue;
	}
	if (!redo)
	    walk = &(*walk)->next;
	else {
	    walk = root;
	    dot = dotdot = redo = 0;
	}
    }
    if (dots && !dot)
	printf("%s\n  \".\" is missing. Can't fix this yet.\n",
	       path_name(parent));
    if (dots && !dotdot)
	printf("%s\n  \"..\" is missing. Can't fix this yet.\n",
	       path_name(parent));
    return 0;
}

/**
 * Check a dentry's cluster chain for bad clusters.
 * If requested, we verify readability and mark unreadable clusters as bad.
 *
 * @param[inout]    fs          Information about the filesystem
 * @param[in]       file        dentry to check
 * @param[in]       read_test   Nonzero == verify that dentry's clusters can
 *                              be read
 */
static void test_file(DOS_FS * fs, DOS_FILE * file, int read_test)
{
    DOS_FILE *owner;
    unsigned long walk, prev, clusters, next_clu;

    prev = clusters = 0;
    for (walk = FSTART(file, fs); walk > 0 && walk < fs->clusters + 2;
	 walk = next_clu) {
	next_clu = next_cluster(fs, walk);

	/* In this stage we are checking only for a loop within our own
	 * cluster chain.
	 * Cross-linking of clusters is handled in check_file()
	 */
	if ((owner = get_owner(fs, walk))) {
	    if (owner == file) {
		printf("%s\n  Circular cluster chain. Truncating to %lu "
		       "cluster%s.\n", path_name(file), clusters,
		       clusters == 1 ? "" : "s");
		if (prev)
		    set_fat(fs, prev, -1);
		else if (!file->offset)
		    die("Bad FAT32 root directory! (bad start cluster)\n");
		else
		    MODIFY_START(file, 0, fs);
	    }
	    break;
	}
	if (bad_cluster(fs, walk))
	    break;
	if (read_test) {
	    if (fs_test(cluster_start(fs, walk), fs->cluster_size)) {
		prev = walk;
		clusters++;
	    } else {
		printf("%s\n  Cluster %lu (%lu) is unreadable. Skipping it.\n",
		       path_name(file), clusters, walk);
		if (prev)
		    set_fat(fs, prev, next_cluster(fs, walk));
		else
		    MODIFY_START(file, next_cluster(fs, walk), fs);
		set_fat(fs, walk, -2);
	    }
	}
	set_owner(fs, walk, file);
    }
    /* Revert ownership (for now) */
    for (walk = FSTART(file, fs); walk > 0 && walk < fs->clusters + 2;
	 walk = next_cluster(fs, walk))
	if (bad_cluster(fs, walk))
	    break;
	else if (get_owner(fs, walk) == file)
	    set_owner(fs, walk, NULL);
	else
	    break;
}

static void undelete(DOS_FS * fs, DOS_FILE * file)
{
    unsigned long clusters, left, prev, walk;

    clusters = left = (CF_LE_L(file->dir_ent.size) + fs->cluster_size - 1) /
	fs->cluster_size;
    prev = 0;

    walk = FSTART(file, fs);

    while (left && (walk >= 2) && (walk < fs->clusters + 2)) {

	FAT_ENTRY curEntry;
	get_fat(&curEntry, fs->fat, walk, fs);

	if (!curEntry.value)
	    break;

	left--;
	if (prev)
	    set_fat(fs, prev, walk);
	prev = walk;
	walk++;
    }
    if (prev)
	set_fat(fs, prev, -1);
    else
	MODIFY_START(file, 0, fs);
    if (left)
	printf("Warning: Did only undelete %lu of %lu cluster%s.\n",
	       clusters - left, clusters, clusters == 1 ? "" : "s");

}

static void new_dir(void)
{
    lfn_reset();
}

/**
 * Create a description for a referenced dentry and insert it in our dentry
 * tree. Then, go check the dentry's cluster chain for bad clusters and
 * cluster loops.
 *
 * @param[inout]    fs      Information about the filesystem
 * @param[out]      chain
 * @param[in]       parent  Information about parent directory of this file
 *                          NULL == no parent ('file' is root directory)
 * @param[in]       offset  Partition-relative byte offset of directory entry of interest
 *                          0 == Root directory
 * @param           cp
 */
static void add_file(DOS_FS * fs, DOS_FILE *** chain, DOS_FILE * parent,
		     loff_t offset, FDSC ** cp)
{
    DOS_FILE *new;
    DIR_ENT de;
    FD_TYPE type;

    if (offset)
	fs_read(offset, sizeof(DIR_ENT), &de);
    else {
	/* Construct a DIR_ENT for the root directory */
	memcpy(de.name, "           ", MSDOS_NAME);
	de.attr = ATTR_DIR;
	de.size = de.time = de.date = 0;
	de.start = CT_LE_W(fs->root_cluster & 0xffff);
	de.starthi = CT_LE_W((fs->root_cluster >> 16) & 0xffff);
    }
    if ((type = file_type(cp, (char *)de.name)) != fdt_none) {
	if (type == fdt_undelete && (de.attr & ATTR_DIR))
	    die("Can't undelete directories.");
	file_modify(cp, (char *)de.name);
	fs_write(offset, 1, &de);
    }
    if (IS_FREE(de.name)) {
	lfn_check_orphaned();
	return;
    }
    if (de.attr == VFAT_LN_ATTR) {
	lfn_add_slot(&de, offset);
	return;
    }
    new = qalloc(&mem_queue, sizeof(DOS_FILE));
    new->lfn = lfn_get(&de, &new->lfn_offset);
    new->offset = offset;
    memcpy(&new->dir_ent, &de, sizeof(de));
    new->next = new->first = NULL;
    new->parent = parent;
    if (type == fdt_undelete)
	undelete(fs, new);
    **chain = new;
    *chain = &new->next;
    if (list) {
	printf("Checking file %s", path_name(new));
	if (new->lfn)
	    printf(" (%s)", file_name(new->dir_ent.name));	/* (8.3) */
	printf("\n");
    }
    /* Don't include root directory, '.', or '..' in the total file count */
    if (offset &&
	strncmp((const char *)de.name, MSDOS_DOT, MSDOS_NAME) != 0 &&
	strncmp((const char *)de.name, MSDOS_DOTDOT, MSDOS_NAME) != 0)
	++n_files;
    test_file(fs, new, test);	/* Bad cluster check */
}

static int subdirs(DOS_FS * fs, DOS_FILE * parent, FDSC ** cp);

static int scan_dir(DOS_FS * fs, DOS_FILE * this, FDSC ** cp)
{
    DOS_FILE **chain;
    int i;
    unsigned long clu_num;

    chain = &this->first;
    i = 0;
    clu_num = FSTART(this, fs);
    new_dir();
    while (clu_num > 0 && clu_num != -1) {
	add_file(fs, &chain, this,
		 cluster_start(fs, clu_num) + (i % fs->cluster_size), cp);
	i += sizeof(DIR_ENT);
	if (!(i % fs->cluster_size))
	    if ((clu_num = next_cluster(fs, clu_num)) == 0 || clu_num == -1)
		break;
    }
    lfn_check_orphaned();
    if (check_dir(fs, &this->first, this->offset))
	return 0;
    if (check_files(fs, this->first))
	return 1;
    return subdirs(fs, this, cp);
}

/**
 * Recursively scan subdirectories of the specified parent directory.
 *
 * @param[inout]    fs      Information about the filesystem
 * @param[in]       parent  Identifies the directory to scan
 * @param[in]       cp
 *
 * @return  0   Success
 * @return  1   Error
 */
static int subdirs(DOS_FS * fs, DOS_FILE * parent, FDSC ** cp)
{
    DOS_FILE *walk;

    for (walk = parent ? parent->first : root; walk; walk = walk->next)
	if (walk->dir_ent.attr & ATTR_DIR)
	    if (strncmp((const char *)walk->dir_ent.name, MSDOS_DOT, MSDOS_NAME)
		&& strncmp((const char *)walk->dir_ent.name, MSDOS_DOTDOT,
			   MSDOS_NAME))
		if (scan_dir(fs, walk, file_cd(cp, (char *)walk->dir_ent.name)))
		    return 1;
    return 0;
}

/**
 * Scan all directory and file information for errors.
 *
 * @param[inout]    fs      Information about the filesystem
 *
 * @return  0   Success
 * @return  1   Error
 */
int scan_root(DOS_FS * fs)
{
    DOS_FILE **chain;
    int i;

    root = NULL;
    chain = &root;
    new_dir();
    if (fs->root_cluster) {
	add_file(fs, &chain, NULL, 0, &fp_root);
    } else {
	for (i = 0; i < fs->root_entries; i++)
	    add_file(fs, &chain, NULL, fs->root_start + i * sizeof(DIR_ENT),
		     &fp_root);
    }
    lfn_check_orphaned();
    (void)check_dir(fs, &root, 0);
    if (check_files(fs, root))
	return 1;
    return subdirs(fs, NULL, &fp_root);
}