summaryrefslogtreecommitdiff
path: root/src/test_fuzzer.c
blob: 10496f2ea74ff25f45b1a494c3a6dc83d64243c6 (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
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
/*
** 2011 March 24
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Code for a demonstration virtual table that generates variations
** on an input word at increasing edit distances from the original.
**
** A fuzzer virtual table is created like this:
**
**     CREATE VIRTUAL TABLE f USING fuzzer(<fuzzer-data-table>);
**
** When it is created, the new fuzzer table must be supplied with the
** name of a "fuzzer data table", which must reside in the same database
** file as the new fuzzer table. The fuzzer data table contains the various
** transformations and their costs that the fuzzer logic uses to generate
** variations.
**
** The fuzzer data table must contain exactly four columns (more precisely,
** the statement "SELECT * FROM <fuzzer_data_table>" must return records
** that consist of four columns). It does not matter what the columns are
** named. 
**
** Each row in the fuzzer data table represents a single character
** transformation. The left most column of the row (column 0) contains an
** integer value - the identifier of the ruleset to which the transformation
** rule belongs (see "MULTIPLE RULE SETS" below). The second column of the
** row (column 0) contains the input character or characters. The third 
** column contains the output character or characters. And the fourth column
** contains the integer cost of making the transformation. For example:
**
**    CREATE TABLE f_data(ruleset, cFrom, cTo, Cost);
**    INSERT INTO f_data(ruleset, cFrom, cTo, Cost) VALUES(0, '', 'a', 100);
**    INSERT INTO f_data(ruleset, cFrom, cTo, Cost) VALUES(0, 'b', '', 87);
**    INSERT INTO f_data(ruleset, cFrom, cTo, Cost) VALUES(0, 'o', 'oe', 38);
**    INSERT INTO f_data(ruleset, cFrom, cTo, Cost) VALUES(0, 'oe', 'o', 40);
**
** The first row inserted into the fuzzer data table by the SQL script
** above indicates that the cost of inserting a letter 'a' is 100.  (All 
** costs are integers.  We recommend that costs be scaled so that the 
** average cost is around 100.) The second INSERT statement creates a rule
** saying that the cost of deleting a single letter 'b' is 87.  The third
** and fourth INSERT statements mean that the cost of transforming a
** single letter "o" into the two-letter sequence "oe" is 38 and that the
** cost of transforming "oe" back into "o" is 40.
**
** The contents of the fuzzer data table are loaded into main memory when
** a fuzzer table is first created, and may be internally reloaded by the
** system at any subsequent time. Therefore, the fuzzer data table should be 
** populated before the fuzzer table is created and not modified thereafter.
** If you do need to modify the contents of the fuzzer data table, it is
** recommended that the associated fuzzer table be dropped, the fuzzer data
** table edited, and the fuzzer table recreated within a single transaction.
** Alternatively, the fuzzer data table can be edited then the database
** connection can be closed and reopened.
**
** Once it has been created, the fuzzer table can be queried as follows:
**
**    SELECT word, distance FROM f
**     WHERE word MATCH 'abcdefg'
**       AND distance<200;
**
** This first query outputs the string "abcdefg" and all strings that
** can be derived from that string by appling the specified transformations.
** The strings are output together with their total transformation cost
** (called "distance") and appear in order of increasing cost.  No string
** is output more than once.  If there are multiple ways to transform the
** target string into the output string then the lowest cost transform is
** the one that is returned.  In the example, the search is limited to 
** strings with a total distance of less than 200.
**
** The fuzzer is a read-only table.  Any attempt to DELETE, INSERT, or
** UPDATE on a fuzzer table will throw an error.
**
** It is important to put some kind of a limit on the fuzzer output.  This
** can be either in the form of a LIMIT clause at the end of the query,
** or better, a "distance<NNN" constraint where NNN is some number.  The
** running time and memory requirement is exponential in the value of NNN 
** so you want to make sure that NNN is not too big.  A value of NNN that
** is about twice the average transformation cost seems to give good results.
**
** The fuzzer table can be useful for tasks such as spelling correction.
** Suppose there is a second table vocabulary(w) where the w column contains
** all correctly spelled words.   Let $word be a word you want to look up.
**
**   SELECT vocabulary.w FROM f, vocabulary
**    WHERE f.word MATCH $word
**      AND f.distance<=200
**      AND f.word=vocabulary.w
**    LIMIT 20
**
** The query above gives the 20 closest words to the $word being tested.
** (Note that for good performance, the vocubulary.w column should be
** indexed.)
**
** A similar query can be used to find all words in the dictionary that
** begin with some prefix $prefix:
**
**   SELECT vocabulary.w FROM f, vocabulary
**    WHERE f.word MATCH $prefix
**      AND f.distance<=200
**      AND vocabulary.w BETWEEN f.word AND (f.word || x'F7BFBFBF')
**    LIMIT 50
**
** This last query will show up to 50 words out of the vocabulary that
** match or nearly match the $prefix.
**
** MULTIPLE RULE SETS
**
** Normally, the "ruleset" value associated with all character transformations
** in the fuzzer data table is zero. However, if required, the fuzzer table
** allows multiple rulesets to be defined. Each query uses only a single
** ruleset. This allows, for example, a single fuzzer table to support 
** multiple languages.
**
** By default, only the rules from ruleset 0 are used. To specify an 
** alternative ruleset, a "ruleset = ?" expression must be added to the
** WHERE clause of a SELECT, where ? is the identifier of the desired 
** ruleset. For example:
**
**   SELECT vocabulary.w FROM f, vocabulary
**    WHERE f.word MATCH $word
**      AND f.distance<=200
**      AND f.word=vocabulary.w
**      AND f.ruleset=1  -- Specify the ruleset to use here
**    LIMIT 20
**
** If no "ruleset = ?" constraint is specified in the WHERE clause, ruleset 
** 0 is used.
**
** LIMITS
**
** The maximum ruleset number is 2147483647.  The maximum length of either
** of the strings in the second or third column of the fuzzer data table
** is 50 bytes.  The maximum cost on a rule is 1000.
*/

/* If SQLITE_DEBUG is not defined, disable assert statements. */
#if !defined(NDEBUG) && !defined(SQLITE_DEBUG)
# define NDEBUG
#endif

#include "sqlite3.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>

#ifndef SQLITE_OMIT_VIRTUALTABLE

/*
** Forward declaration of objects used by this implementation
*/
typedef struct fuzzer_vtab fuzzer_vtab;
typedef struct fuzzer_cursor fuzzer_cursor;
typedef struct fuzzer_rule fuzzer_rule;
typedef struct fuzzer_seen fuzzer_seen;
typedef struct fuzzer_stem fuzzer_stem;

/*
** Various types.
**
** fuzzer_cost is the "cost" of an edit operation.
**
** fuzzer_len is the length of a matching string.  
**
** fuzzer_ruleid is an ruleset identifier.
*/
typedef int fuzzer_cost;
typedef signed char fuzzer_len;
typedef int fuzzer_ruleid;

/*
** Limits
*/
#define FUZZER_MX_LENGTH           50   /* Maximum length of a rule string */
#define FUZZER_MX_RULEID   2147483647   /* Maximum rule ID */
#define FUZZER_MX_COST           1000   /* Maximum single-rule cost */
#define FUZZER_MX_OUTPUT_LENGTH   100   /* Maximum length of an output string */


/*
** Each transformation rule is stored as an instance of this object.
** All rules are kept on a linked list sorted by rCost.
*/
struct fuzzer_rule {
  fuzzer_rule *pNext;         /* Next rule in order of increasing rCost */
  char *zFrom;                /* Transform from */
  fuzzer_cost rCost;          /* Cost of this transformation */
  fuzzer_len nFrom, nTo;      /* Length of the zFrom and zTo strings */
  fuzzer_ruleid iRuleset;     /* The rule set to which this rule belongs */
  char zTo[4];                /* Transform to (extra space appended) */
};

/*
** A stem object is used to generate variants.  It is also used to record
** previously generated outputs.
**
** Every stem is added to a hash table as it is output.  Generation of
** duplicate stems is suppressed.
**
** Active stems (those that might generate new outputs) are kepts on a linked
** list sorted by increasing cost.  The cost is the sum of rBaseCost and
** pRule->rCost.
*/
struct fuzzer_stem {
  char *zBasis;              /* Word being fuzzed */
  const fuzzer_rule *pRule;  /* Current rule to apply */
  fuzzer_stem *pNext;        /* Next stem in rCost order */
  fuzzer_stem *pHash;        /* Next stem with same hash on zBasis */
  fuzzer_cost rBaseCost;     /* Base cost of getting to zBasis */
  fuzzer_cost rCostX;        /* Precomputed rBaseCost + pRule->rCost */
  fuzzer_len nBasis;         /* Length of the zBasis string */
  fuzzer_len n;              /* Apply pRule at this character offset */
};

/* 
** A fuzzer virtual-table object 
*/
struct fuzzer_vtab {
  sqlite3_vtab base;         /* Base class - must be first */
  char *zClassName;          /* Name of this class.  Default: "fuzzer" */
  fuzzer_rule *pRule;        /* All active rules in this fuzzer */
  int nCursor;               /* Number of active cursors */
};

#define FUZZER_HASH  4001    /* Hash table size */
#define FUZZER_NQUEUE  20    /* Number of slots on the stem queue */

/* A fuzzer cursor object */
struct fuzzer_cursor {
  sqlite3_vtab_cursor base;  /* Base class - must be first */
  sqlite3_int64 iRowid;      /* The rowid of the current word */
  fuzzer_vtab *pVtab;        /* The virtual table this cursor belongs to */
  fuzzer_cost rLimit;        /* Maximum cost of any term */
  fuzzer_stem *pStem;        /* Stem with smallest rCostX */
  fuzzer_stem *pDone;        /* Stems already processed to completion */
  fuzzer_stem *aQueue[FUZZER_NQUEUE];  /* Queue of stems with higher rCostX */
  int mxQueue;               /* Largest used index in aQueue[] */
  char *zBuf;                /* Temporary use buffer */
  int nBuf;                  /* Bytes allocated for zBuf */
  int nStem;                 /* Number of stems allocated */
  int iRuleset;              /* Only process rules from this ruleset */
  fuzzer_rule nullRule;      /* Null rule used first */
  fuzzer_stem *apHash[FUZZER_HASH]; /* Hash of previously generated terms */
};

/*
** The two input rule lists are both sorted in order of increasing
** cost.  Merge them together into a single list, sorted by cost, and
** return a pointer to the head of that list.
*/
static fuzzer_rule *fuzzerMergeRules(fuzzer_rule *pA, fuzzer_rule *pB){
  fuzzer_rule head;
  fuzzer_rule *pTail;

  pTail =  &head;
  while( pA && pB ){
    if( pA->rCost<=pB->rCost ){
      pTail->pNext = pA;
      pTail = pA;
      pA = pA->pNext;
    }else{
      pTail->pNext = pB;
      pTail = pB;
      pB = pB->pNext;
    }
  }
  if( pA==0 ){
    pTail->pNext = pB;
  }else{
    pTail->pNext = pA;
  }
  return head.pNext;
}

/*
** Statement pStmt currently points to a row in the fuzzer data table. This
** function allocates and populates a fuzzer_rule structure according to
** the content of the row.
**
** If successful, *ppRule is set to point to the new object and SQLITE_OK
** is returned. Otherwise, *ppRule is zeroed, *pzErr may be set to point
** to an error message and an SQLite error code returned.
*/
static int fuzzerLoadOneRule(
  fuzzer_vtab *p,                 /* Fuzzer virtual table handle */
  sqlite3_stmt *pStmt,            /* Base rule on statements current row */
  fuzzer_rule **ppRule,           /* OUT: New rule object */
  char **pzErr                    /* OUT: Error message */
){
  sqlite3_int64 iRuleset = sqlite3_column_int64(pStmt, 0);
  const char *zFrom = (const char *)sqlite3_column_text(pStmt, 1);
  const char *zTo = (const char *)sqlite3_column_text(pStmt, 2);
  int nCost = sqlite3_column_int(pStmt, 3);

  int rc = SQLITE_OK;             /* Return code */
  int nFrom;                      /* Size of string zFrom, in bytes */
  int nTo;                        /* Size of string zTo, in bytes */
  fuzzer_rule *pRule = 0;         /* New rule object to return */

  if( zFrom==0 ) zFrom = "";
  if( zTo==0 ) zTo = "";
  nFrom = (int)strlen(zFrom);
  nTo = (int)strlen(zTo);

  /* Silently ignore null transformations */
  if( strcmp(zFrom, zTo)==0 ){
    *ppRule = 0;
    return SQLITE_OK;
  }

  if( nCost<=0 || nCost>FUZZER_MX_COST ){
    *pzErr = sqlite3_mprintf("%s: cost must be between 1 and %d", 
        p->zClassName, FUZZER_MX_COST
    );
    rc = SQLITE_ERROR;
  }else
  if( nFrom>FUZZER_MX_LENGTH || nTo>FUZZER_MX_LENGTH ){
    *pzErr = sqlite3_mprintf("%s: maximum string length is %d", 
        p->zClassName, FUZZER_MX_LENGTH
    );
    rc = SQLITE_ERROR;    
  }else
  if( iRuleset<0 || iRuleset>FUZZER_MX_RULEID ){
    *pzErr = sqlite3_mprintf("%s: ruleset must be between 0 and %d", 
        p->zClassName, FUZZER_MX_RULEID
    );
    rc = SQLITE_ERROR;    
  }else{

    pRule = sqlite3_malloc( sizeof(*pRule) + nFrom + nTo );
    if( pRule==0 ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pRule, 0, sizeof(*pRule));
      pRule->zFrom = &pRule->zTo[nTo+1];
      pRule->nFrom = nFrom;
      memcpy(pRule->zFrom, zFrom, nFrom+1);
      memcpy(pRule->zTo, zTo, nTo+1);
      pRule->nTo = nTo;
      pRule->rCost = nCost;
      pRule->iRuleset = (int)iRuleset;
    }
  }

  *ppRule = pRule;
  return rc;
}

/*
** Load the content of the fuzzer data table into memory.
*/
static int fuzzerLoadRules(
  sqlite3 *db,                    /* Database handle */
  fuzzer_vtab *p,                 /* Virtual fuzzer table to configure */
  const char *zDb,                /* Database containing rules data */
  const char *zData,              /* Table containing rules data */
  char **pzErr                    /* OUT: Error message */
){
  int rc = SQLITE_OK;             /* Return code */
  char *zSql;                     /* SELECT used to read from rules table */
  fuzzer_rule *pHead = 0;

  zSql = sqlite3_mprintf("SELECT * FROM %Q.%Q", zDb, zData);
  if( zSql==0 ){
    rc = SQLITE_NOMEM;
  }else{
    int rc2;                      /* finalize() return code */
    sqlite3_stmt *pStmt = 0;
    rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
    if( rc!=SQLITE_OK ){
      *pzErr = sqlite3_mprintf("%s: %s", p->zClassName, sqlite3_errmsg(db));
    }else if( sqlite3_column_count(pStmt)!=4 ){
      *pzErr = sqlite3_mprintf("%s: %s has %d columns, expected 4",
          p->zClassName, zData, sqlite3_column_count(pStmt)
      );
      rc = SQLITE_ERROR;
    }else{
      while( rc==SQLITE_OK && SQLITE_ROW==sqlite3_step(pStmt) ){
        fuzzer_rule *pRule = 0;
        rc = fuzzerLoadOneRule(p, pStmt, &pRule, pzErr);
        if( pRule ){
          pRule->pNext = pHead;
          pHead = pRule;
        }
      }
    }
    rc2 = sqlite3_finalize(pStmt);
    if( rc==SQLITE_OK ) rc = rc2;
  }
  sqlite3_free(zSql);

  /* All rules are now in a singly linked list starting at pHead. This
  ** block sorts them by cost and then sets fuzzer_vtab.pRule to point to 
  ** point to the head of the sorted list.
  */
  if( rc==SQLITE_OK ){
    unsigned int i;
    fuzzer_rule *pX;
    fuzzer_rule *a[15];
    for(i=0; i<sizeof(a)/sizeof(a[0]); i++) a[i] = 0;
    while( (pX = pHead)!=0 ){
      pHead = pX->pNext;
      pX->pNext = 0;
      for(i=0; a[i] && i<sizeof(a)/sizeof(a[0])-1; i++){
        pX = fuzzerMergeRules(a[i], pX);
        a[i] = 0;
      }
      a[i] = fuzzerMergeRules(a[i], pX);
    }
    for(pX=a[0], i=1; i<sizeof(a)/sizeof(a[0]); i++){
      pX = fuzzerMergeRules(a[i], pX);
    }
    p->pRule = fuzzerMergeRules(p->pRule, pX);
  }else{
    /* An error has occurred. Setting p->pRule to point to the head of the
    ** allocated list ensures that the list will be cleaned up in this case.
    */
    assert( p->pRule==0 );
    p->pRule = pHead;
  }

  return rc;
}

/*
** This function converts an SQL quoted string into an unquoted string
** and returns a pointer to a buffer allocated using sqlite3_malloc() 
** containing the result. The caller should eventually free this buffer
** using sqlite3_free.
**
** Examples:
**
**     "abc"   becomes   abc
**     'xyz'   becomes   xyz
**     [pqr]   becomes   pqr
**     `mno`   becomes   mno
*/
static char *fuzzerDequote(const char *zIn){
  int nIn;                        /* Size of input string, in bytes */
  char *zOut;                     /* Output (dequoted) string */

  nIn = (int)strlen(zIn);
  zOut = sqlite3_malloc(nIn+1);
  if( zOut ){
    char q = zIn[0];              /* Quote character (if any ) */

    if( q!='[' && q!= '\'' && q!='"' && q!='`' ){
      memcpy(zOut, zIn, nIn+1);
    }else{
      int iOut = 0;               /* Index of next byte to write to output */
      int iIn;                    /* Index of next byte to read from input */

      if( q=='[' ) q = ']';
      for(iIn=1; iIn<nIn; iIn++){
        if( zIn[iIn]==q ) iIn++;
        zOut[iOut++] = zIn[iIn];
      }
    }
    assert( (int)strlen(zOut)<=nIn );
  }
  return zOut;
}

/*
** xDisconnect/xDestroy method for the fuzzer module.
*/
static int fuzzerDisconnect(sqlite3_vtab *pVtab){
  fuzzer_vtab *p = (fuzzer_vtab*)pVtab;
  assert( p->nCursor==0 );
  while( p->pRule ){
    fuzzer_rule *pRule = p->pRule;
    p->pRule = pRule->pNext;
    sqlite3_free(pRule);
  }
  sqlite3_free(p);
  return SQLITE_OK;
}

/*
** xConnect/xCreate method for the fuzzer module. Arguments are:
**
**   argv[0]   -> module name  ("fuzzer")
**   argv[1]   -> database name
**   argv[2]   -> table name
**   argv[3]   -> fuzzer rule table name
*/
static int fuzzerConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  int rc = SQLITE_OK;             /* Return code */
  fuzzer_vtab *pNew = 0;          /* New virtual table */
  const char *zModule = argv[0];
  const char *zDb = argv[1];

  if( argc!=4 ){
    *pzErr = sqlite3_mprintf(
        "%s: wrong number of CREATE VIRTUAL TABLE arguments", zModule
    );
    rc = SQLITE_ERROR;
  }else{
    int nModule;                  /* Length of zModule, in bytes */

    nModule = (int)strlen(zModule);
    pNew = sqlite3_malloc( sizeof(*pNew) + nModule + 1);
    if( pNew==0 ){
      rc = SQLITE_NOMEM;
    }else{
      char *zTab;                 /* Dequoted name of fuzzer data table */

      memset(pNew, 0, sizeof(*pNew));
      pNew->zClassName = (char*)&pNew[1];
      memcpy(pNew->zClassName, zModule, nModule+1);

      zTab = fuzzerDequote(argv[3]);
      if( zTab==0 ){
        rc = SQLITE_NOMEM;
      }else{
        rc = fuzzerLoadRules(db, pNew, zDb, zTab, pzErr);
        sqlite3_free(zTab);
      }

      if( rc==SQLITE_OK ){
        rc = sqlite3_declare_vtab(db, "CREATE TABLE x(word,distance,ruleset)");
      }
      if( rc!=SQLITE_OK ){
        fuzzerDisconnect((sqlite3_vtab *)pNew);
        pNew = 0;
      }
    }
  }

  *ppVtab = (sqlite3_vtab *)pNew;
  return rc;
}

/*
** Open a new fuzzer cursor.
*/
static int fuzzerOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
  fuzzer_vtab *p = (fuzzer_vtab*)pVTab;
  fuzzer_cursor *pCur;
  pCur = sqlite3_malloc( sizeof(*pCur) );
  if( pCur==0 ) return SQLITE_NOMEM;
  memset(pCur, 0, sizeof(*pCur));
  pCur->pVtab = p;
  *ppCursor = &pCur->base;
  p->nCursor++;
  return SQLITE_OK;
}

/*
** Free all stems in a list.
*/
static void fuzzerClearStemList(fuzzer_stem *pStem){
  while( pStem ){
    fuzzer_stem *pNext = pStem->pNext;
    sqlite3_free(pStem);
    pStem = pNext;
  }
}

/*
** Free up all the memory allocated by a cursor.  Set it rLimit to 0
** to indicate that it is at EOF.
*/
static void fuzzerClearCursor(fuzzer_cursor *pCur, int clearHash){
  int i;
  fuzzerClearStemList(pCur->pStem);
  fuzzerClearStemList(pCur->pDone);
  for(i=0; i<FUZZER_NQUEUE; i++) fuzzerClearStemList(pCur->aQueue[i]);
  pCur->rLimit = (fuzzer_cost)0;
  if( clearHash && pCur->nStem ){
    pCur->mxQueue = 0;
    pCur->pStem = 0;
    pCur->pDone = 0;
    memset(pCur->aQueue, 0, sizeof(pCur->aQueue));
    memset(pCur->apHash, 0, sizeof(pCur->apHash));
  }
  pCur->nStem = 0;
}

/*
** Close a fuzzer cursor.
*/
static int fuzzerClose(sqlite3_vtab_cursor *cur){
  fuzzer_cursor *pCur = (fuzzer_cursor *)cur;
  fuzzerClearCursor(pCur, 0);
  sqlite3_free(pCur->zBuf);
  pCur->pVtab->nCursor--;
  sqlite3_free(pCur);
  return SQLITE_OK;
}

/*
** Compute the current output term for a fuzzer_stem.
*/
static int fuzzerRender(
  fuzzer_stem *pStem,   /* The stem to be rendered */
  char **pzBuf,         /* Write results into this buffer.  realloc if needed */
  int *pnBuf            /* Size of the buffer */
){
  const fuzzer_rule *pRule = pStem->pRule;
  int n;                          /* Size of output term without nul-term */
  char *z;                        /* Buffer to assemble output term in */

  n = pStem->nBasis + pRule->nTo - pRule->nFrom;
  if( (*pnBuf)<n+1 ){
    (*pzBuf) = sqlite3_realloc((*pzBuf), n+100);
    if( (*pzBuf)==0 ) return SQLITE_NOMEM;
    (*pnBuf) = n+100;
  }
  n = pStem->n;
  z = *pzBuf;
  if( n<0 ){
    memcpy(z, pStem->zBasis, pStem->nBasis+1);
  }else{
    memcpy(z, pStem->zBasis, n);
    memcpy(&z[n], pRule->zTo, pRule->nTo);
    memcpy(&z[n+pRule->nTo], &pStem->zBasis[n+pRule->nFrom], 
           pStem->nBasis-n-pRule->nFrom+1);
  }

  assert( z[pStem->nBasis + pRule->nTo - pRule->nFrom]==0 );
  return SQLITE_OK;
}

/*
** Compute a hash on zBasis.
*/
static unsigned int fuzzerHash(const char *z){
  unsigned int h = 0;
  while( *z ){ h = (h<<3) ^ (h>>29) ^ *(z++); }
  return h % FUZZER_HASH;
}

/*
** Current cost of a stem
*/
static fuzzer_cost fuzzerCost(fuzzer_stem *pStem){
  return pStem->rCostX = pStem->rBaseCost + pStem->pRule->rCost;
}

#if 0
/*
** Print a description of a fuzzer_stem on stderr.
*/
static void fuzzerStemPrint(
  const char *zPrefix,
  fuzzer_stem *pStem,
  const char *zSuffix
){
  if( pStem->n<0 ){
    fprintf(stderr, "%s[%s](%d)-->self%s",
       zPrefix,
       pStem->zBasis, pStem->rBaseCost,
       zSuffix
    );
  }else{
    char *zBuf = 0;
    int nBuf = 0;
    if( fuzzerRender(pStem, &zBuf, &nBuf)!=SQLITE_OK ) return;
    fprintf(stderr, "%s[%s](%d)-->{%s}(%d)%s",
      zPrefix,
      pStem->zBasis, pStem->rBaseCost, zBuf, pStem->,
      zSuffix
    );
    sqlite3_free(zBuf);
  }
}
#endif

/*
** Return 1 if the string to which the cursor is point has already
** been emitted.  Return 0 if not.  Return -1 on a memory allocation
** failures.
*/
static int fuzzerSeen(fuzzer_cursor *pCur, fuzzer_stem *pStem){
  unsigned int h;
  fuzzer_stem *pLookup;

  if( fuzzerRender(pStem, &pCur->zBuf, &pCur->nBuf)==SQLITE_NOMEM ){
    return -1;
  }
  h = fuzzerHash(pCur->zBuf);
  pLookup = pCur->apHash[h];
  while( pLookup && strcmp(pLookup->zBasis, pCur->zBuf)!=0 ){
    pLookup = pLookup->pHash;
  }
  return pLookup!=0;
}

/*
** If argument pRule is NULL, this function returns false.
**
** Otherwise, it returns true if rule pRule should be skipped. A rule 
** should be skipped if it does not belong to rule-set iRuleset, or if
** applying it to stem pStem would create a string longer than 
** FUZZER_MX_OUTPUT_LENGTH bytes.
*/
static int fuzzerSkipRule(
  const fuzzer_rule *pRule,       /* Determine whether or not to skip this */
  fuzzer_stem *pStem,             /* Stem rule may be applied to */
  int iRuleset                    /* Rule-set used by the current query */
){
  return pRule && (
      (pRule->iRuleset!=iRuleset)
   || (pStem->nBasis + pRule->nTo - pRule->nFrom)>FUZZER_MX_OUTPUT_LENGTH
  );
}

/*
** Advance a fuzzer_stem to its next value.   Return 0 if there are
** no more values that can be generated by this fuzzer_stem.  Return
** -1 on a memory allocation failure.
*/
static int fuzzerAdvance(fuzzer_cursor *pCur, fuzzer_stem *pStem){
  const fuzzer_rule *pRule;
  while( (pRule = pStem->pRule)!=0 ){
    assert( pRule==&pCur->nullRule || pRule->iRuleset==pCur->iRuleset );
    while( pStem->n < pStem->nBasis - pRule->nFrom ){
      pStem->n++;
      if( pRule->nFrom==0
       || memcmp(&pStem->zBasis[pStem->n], pRule->zFrom, pRule->nFrom)==0
      ){
        /* Found a rewrite case.  Make sure it is not a duplicate */
        int rc = fuzzerSeen(pCur, pStem);
        if( rc<0 ) return -1;
        if( rc==0 ){
          fuzzerCost(pStem);
          return 1;
        }
      }
    }
    pStem->n = -1;
    do{
      pRule = pRule->pNext;
    }while( fuzzerSkipRule(pRule, pStem, pCur->iRuleset) );
    pStem->pRule = pRule;
    if( pRule && fuzzerCost(pStem)>pCur->rLimit ) pStem->pRule = 0;
  }
  return 0;
}

/*
** The two input stem lists are both sorted in order of increasing
** rCostX.  Merge them together into a single list, sorted by rCostX, and
** return a pointer to the head of that new list.
*/
static fuzzer_stem *fuzzerMergeStems(fuzzer_stem *pA, fuzzer_stem *pB){
  fuzzer_stem head;
  fuzzer_stem *pTail;

  pTail =  &head;
  while( pA && pB ){
    if( pA->rCostX<=pB->rCostX ){
      pTail->pNext = pA;
      pTail = pA;
      pA = pA->pNext;
    }else{
      pTail->pNext = pB;
      pTail = pB;
      pB = pB->pNext;
    }
  }
  if( pA==0 ){
    pTail->pNext = pB;
  }else{
    pTail->pNext = pA;
  }
  return head.pNext;
}

/*
** Load pCur->pStem with the lowest-cost stem.  Return a pointer
** to the lowest-cost stem.
*/
static fuzzer_stem *fuzzerLowestCostStem(fuzzer_cursor *pCur){
  fuzzer_stem *pBest, *pX;
  int iBest;
  int i;

  if( pCur->pStem==0 ){
    iBest = -1;
    pBest = 0;
    for(i=0; i<=pCur->mxQueue; i++){
      pX = pCur->aQueue[i];
      if( pX==0 ) continue;
      if( pBest==0 || pBest->rCostX>pX->rCostX ){
        pBest = pX;
        iBest = i;
      }
    } 
    if( pBest ){
      pCur->aQueue[iBest] = pBest->pNext;
      pBest->pNext = 0;
      pCur->pStem = pBest;
    }
  }
  return pCur->pStem;
}

/*
** Insert pNew into queue of pending stems.  Then find the stem
** with the lowest rCostX and move it into pCur->pStem.
** list.  The insert is done such the pNew is in the correct order
** according to fuzzer_stem.zBaseCost+fuzzer_stem.pRule->rCost.
*/
static fuzzer_stem *fuzzerInsert(fuzzer_cursor *pCur, fuzzer_stem *pNew){
  fuzzer_stem *pX;
  int i;

  /* If pCur->pStem exists and is greater than pNew, then make pNew
  ** the new pCur->pStem and insert the old pCur->pStem instead.
  */
  if( (pX = pCur->pStem)!=0 && pX->rCostX>pNew->rCostX ){
    pNew->pNext = 0;
    pCur->pStem = pNew;
    pNew = pX;
  }

  /* Insert the new value */
  pNew->pNext = 0;
  pX = pNew;
  for(i=0; i<=pCur->mxQueue; i++){
    if( pCur->aQueue[i] ){
      pX = fuzzerMergeStems(pX, pCur->aQueue[i]);
      pCur->aQueue[i] = 0;
    }else{
      pCur->aQueue[i] = pX;
      break;
    }
  }
  if( i>pCur->mxQueue ){
    if( i<FUZZER_NQUEUE ){
      pCur->mxQueue = i;
      pCur->aQueue[i] = pX;
    }else{
      assert( pCur->mxQueue==FUZZER_NQUEUE-1 );
      pX = fuzzerMergeStems(pX, pCur->aQueue[FUZZER_NQUEUE-1]);
      pCur->aQueue[FUZZER_NQUEUE-1] = pX;
    }
  }

  return fuzzerLowestCostStem(pCur);
}

/*
** Allocate a new fuzzer_stem.  Add it to the hash table but do not
** link it into either the pCur->pStem or pCur->pDone lists.
*/
static fuzzer_stem *fuzzerNewStem(
  fuzzer_cursor *pCur,
  const char *zWord,
  fuzzer_cost rBaseCost
){
  fuzzer_stem *pNew;
  fuzzer_rule *pRule;
  unsigned int h;

  pNew = sqlite3_malloc( sizeof(*pNew) + (int)strlen(zWord) + 1 );
  if( pNew==0 ) return 0;
  memset(pNew, 0, sizeof(*pNew));
  pNew->zBasis = (char*)&pNew[1];
  pNew->nBasis = (int)strlen(zWord);
  memcpy(pNew->zBasis, zWord, pNew->nBasis+1);
  pRule = pCur->pVtab->pRule;
  while( fuzzerSkipRule(pRule, pNew, pCur->iRuleset) ){
    pRule = pRule->pNext;
  }
  pNew->pRule = pRule;
  pNew->n = -1;
  pNew->rBaseCost = pNew->rCostX = rBaseCost;
  h = fuzzerHash(pNew->zBasis);
  pNew->pHash = pCur->apHash[h];
  pCur->apHash[h] = pNew;
  pCur->nStem++;
  return pNew;
}


/*
** Advance a cursor to its next row of output
*/
static int fuzzerNext(sqlite3_vtab_cursor *cur){
  fuzzer_cursor *pCur = (fuzzer_cursor*)cur;
  int rc;
  fuzzer_stem *pStem, *pNew;

  pCur->iRowid++;

  /* Use the element the cursor is currently point to to create
  ** a new stem and insert the new stem into the priority queue.
  */
  pStem = pCur->pStem;
  if( pStem->rCostX>0 ){
    rc = fuzzerRender(pStem, &pCur->zBuf, &pCur->nBuf);
    if( rc==SQLITE_NOMEM ) return SQLITE_NOMEM;
    pNew = fuzzerNewStem(pCur, pCur->zBuf, pStem->rCostX);
    if( pNew ){
      if( fuzzerAdvance(pCur, pNew)==0 ){
        pNew->pNext = pCur->pDone;
        pCur->pDone = pNew;
      }else{
        if( fuzzerInsert(pCur, pNew)==pNew ){
          return SQLITE_OK;
        }
      }
    }else{
      return SQLITE_NOMEM;
    }
  }

  /* Adjust the priority queue so that the first element of the
  ** stem list is the next lowest cost word.
  */
  while( (pStem = pCur->pStem)!=0 ){
    int res = fuzzerAdvance(pCur, pStem);
    if( res<0 ){
      return SQLITE_NOMEM;
    }else if( res>0 ){
      pCur->pStem = 0;
      pStem = fuzzerInsert(pCur, pStem);
      if( (rc = fuzzerSeen(pCur, pStem))!=0 ){
        if( rc<0 ) return SQLITE_NOMEM;
        continue;
      }
      return SQLITE_OK;  /* New word found */
    }
    pCur->pStem = 0;
    pStem->pNext = pCur->pDone;
    pCur->pDone = pStem;
    if( fuzzerLowestCostStem(pCur) ){
      rc = fuzzerSeen(pCur, pCur->pStem);
      if( rc<0 ) return SQLITE_NOMEM;
      if( rc==0 ){
        return SQLITE_OK;
      }
    }
  }

  /* Reach this point only if queue has been exhausted and there is
  ** nothing left to be output. */
  pCur->rLimit = (fuzzer_cost)0;
  return SQLITE_OK;
}

/*
** Called to "rewind" a cursor back to the beginning so that
** it starts its output over again.  Always called at least once
** prior to any fuzzerColumn, fuzzerRowid, or fuzzerEof call.
*/
static int fuzzerFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  fuzzer_cursor *pCur = (fuzzer_cursor *)pVtabCursor;
  const char *zWord = "";
  fuzzer_stem *pStem;
  int idx;

  fuzzerClearCursor(pCur, 1);
  pCur->rLimit = 2147483647;
  idx = 0;
  if( idxNum & 1 ){
    zWord = (const char*)sqlite3_value_text(argv[0]);
    idx++;
  }
  if( idxNum & 2 ){
    pCur->rLimit = (fuzzer_cost)sqlite3_value_int(argv[idx]);
    idx++;
  }
  if( idxNum & 4 ){
    pCur->iRuleset = (fuzzer_cost)sqlite3_value_int(argv[idx]);
    idx++;
  }
  pCur->nullRule.pNext = pCur->pVtab->pRule;
  pCur->nullRule.rCost = 0;
  pCur->nullRule.nFrom = 0;
  pCur->nullRule.nTo = 0;
  pCur->nullRule.zFrom = "";
  pCur->iRowid = 1;
  assert( pCur->pStem==0 );

  /* If the query term is longer than FUZZER_MX_OUTPUT_LENGTH bytes, this
  ** query will return zero rows.  */
  if( (int)strlen(zWord)<FUZZER_MX_OUTPUT_LENGTH ){
    pCur->pStem = pStem = fuzzerNewStem(pCur, zWord, (fuzzer_cost)0);
    if( pStem==0 ) return SQLITE_NOMEM;
    pStem->pRule = &pCur->nullRule;
    pStem->n = pStem->nBasis;
  }else{
    pCur->rLimit = 0;
  }

  return SQLITE_OK;
}

/*
** Only the word and distance columns have values.  All other columns
** return NULL
*/
static int fuzzerColumn(sqlite3_vtab_cursor *cur, sqlite3_context *ctx, int i){
  fuzzer_cursor *pCur = (fuzzer_cursor*)cur;
  if( i==0 ){
    /* the "word" column */
    if( fuzzerRender(pCur->pStem, &pCur->zBuf, &pCur->nBuf)==SQLITE_NOMEM ){
      return SQLITE_NOMEM;
    }
    sqlite3_result_text(ctx, pCur->zBuf, -1, SQLITE_TRANSIENT);
  }else if( i==1 ){
    /* the "distance" column */
    sqlite3_result_int(ctx, pCur->pStem->rCostX);
  }else{
    /* All other columns are NULL */
    sqlite3_result_null(ctx);
  }
  return SQLITE_OK;
}

/*
** The rowid.
*/
static int fuzzerRowid(sqlite3_vtab_cursor *cur, sqlite_int64 *pRowid){
  fuzzer_cursor *pCur = (fuzzer_cursor*)cur;
  *pRowid = pCur->iRowid;
  return SQLITE_OK;
}

/*
** When the fuzzer_cursor.rLimit value is 0 or less, that is a signal
** that the cursor has nothing more to output.
*/
static int fuzzerEof(sqlite3_vtab_cursor *cur){
  fuzzer_cursor *pCur = (fuzzer_cursor*)cur;
  return pCur->rLimit<=(fuzzer_cost)0;
}

/*
** Search for terms of these forms:
**
**   (A)    word MATCH $str
**   (B1)   distance < $value
**   (B2)   distance <= $value
**   (C)    ruleid == $ruleid
**
** The distance< and distance<= are both treated as distance<=.
** The query plan number is a bit vector:
**
**   bit 1:   Term of the form (A) found
**   bit 2:   Term like (B1) or (B2) found
**   bit 3:   Term like (C) found
**
** If bit-1 is set, $str is always in filter.argv[0].  If bit-2 is set
** then $value is in filter.argv[0] if bit-1 is clear and is in 
** filter.argv[1] if bit-1 is set.  If bit-3 is set, then $ruleid is
** in filter.argv[0] if bit-1 and bit-2 are both zero, is in
** filter.argv[1] if exactly one of bit-1 and bit-2 are set, and is in
** filter.argv[2] if both bit-1 and bit-2 are set.
*/
static int fuzzerBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  int iPlan = 0;
  int iDistTerm = -1;
  int iRulesetTerm = -1;
  int i;
  const struct sqlite3_index_constraint *pConstraint;
  pConstraint = pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++, pConstraint++){
    if( pConstraint->usable==0 ) continue;
    if( (iPlan & 1)==0 
     && pConstraint->iColumn==0
     && pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH
    ){
      iPlan |= 1;
      pIdxInfo->aConstraintUsage[i].argvIndex = 1;
      pIdxInfo->aConstraintUsage[i].omit = 1;
    }
    if( (iPlan & 2)==0
     && pConstraint->iColumn==1
     && (pConstraint->op==SQLITE_INDEX_CONSTRAINT_LT
           || pConstraint->op==SQLITE_INDEX_CONSTRAINT_LE)
    ){
      iPlan |= 2;
      iDistTerm = i;
    }
    if( (iPlan & 4)==0
     && pConstraint->iColumn==2
     && pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ
    ){
      iPlan |= 4;
      pIdxInfo->aConstraintUsage[i].omit = 1;
      iRulesetTerm = i;
    }
  }
  if( iPlan & 2 ){
    pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = 1+((iPlan&1)!=0);
  }
  if( iPlan & 4 ){
    int idx = 1;
    if( iPlan & 1 ) idx++;
    if( iPlan & 2 ) idx++;
    pIdxInfo->aConstraintUsage[iRulesetTerm].argvIndex = idx;
  }
  pIdxInfo->idxNum = iPlan;
  if( pIdxInfo->nOrderBy==1
   && pIdxInfo->aOrderBy[0].iColumn==1
   && pIdxInfo->aOrderBy[0].desc==0
  ){
    pIdxInfo->orderByConsumed = 1;
  }
  pIdxInfo->estimatedCost = (double)10000;
   
  return SQLITE_OK;
}

/*
** A virtual table module that implements the "fuzzer".
*/
static sqlite3_module fuzzerModule = {
  0,                           /* iVersion */
  fuzzerConnect,
  fuzzerConnect,
  fuzzerBestIndex,
  fuzzerDisconnect, 
  fuzzerDisconnect,
  fuzzerOpen,                  /* xOpen - open a cursor */
  fuzzerClose,                 /* xClose - close a cursor */
  fuzzerFilter,                /* xFilter - configure scan constraints */
  fuzzerNext,                  /* xNext - advance a cursor */
  fuzzerEof,                   /* xEof - check for end of scan */
  fuzzerColumn,                /* xColumn - read data */
  fuzzerRowid,                 /* xRowid - read data */
  0,                           /* xUpdate */
  0,                           /* xBegin */
  0,                           /* xSync */
  0,                           /* xCommit */
  0,                           /* xRollback */
  0,                           /* xFindMethod */
  0,                           /* xRename */
};

#endif /* SQLITE_OMIT_VIRTUALTABLE */


/*
** Register the fuzzer virtual table
*/
int fuzzer_register(sqlite3 *db){
  int rc = SQLITE_OK;
#ifndef SQLITE_OMIT_VIRTUALTABLE
  rc = sqlite3_create_module(db, "fuzzer", &fuzzerModule, 0);
#endif
  return rc;
}

#ifdef SQLITE_TEST
#include <tcl.h>
/*
** Decode a pointer to an sqlite3 object.
*/
extern int getDbPointer(Tcl_Interp *interp, const char *zA, sqlite3 **ppDb);

/*
** Register the echo virtual table module.
*/
static int register_fuzzer_module(
  ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
  Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
  int objc,              /* Number of arguments */
  Tcl_Obj *CONST objv[]  /* Command arguments */
){
  sqlite3 *db;
  if( objc!=2 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB");
    return TCL_ERROR;
  }
  getDbPointer(interp, Tcl_GetString(objv[1]), &db);
  fuzzer_register(db);
  return TCL_OK;
}


/*
** Register commands with the TCL interpreter.
*/
int Sqlitetestfuzzer_Init(Tcl_Interp *interp){
  static struct {
     char *zName;
     Tcl_ObjCmdProc *xProc;
     void *clientData;
  } aObjCmd[] = {
     { "register_fuzzer_module",   register_fuzzer_module, 0 },
  };
  int i;
  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){
    Tcl_CreateObjCommand(interp, aObjCmd[i].zName, 
        aObjCmd[i].xProc, aObjCmd[i].clientData, 0);
  }
  return TCL_OK;
}

#endif /* SQLITE_TEST */