third_party/sqlite/src/src/test

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This source file includes following definitions.
fuzzerConnect
fuzzerDisconnect
fuzzerMergeRules
fuzzerOpen
fuzzerClearStemList
fuzzerClearCursor
fuzzerClose
fuzzerRender
fuzzerHash
fuzzerCost
fuzzerStemPrint
fuzzerSeen
fuzzerAdvance
fuzzerMergeStems
fuzzerLowestCostStem
fuzzerInsert
fuzzerNewStem
fuzzerNext
fuzzerFilter
fuzzerColumn
fuzzerRowid
fuzzerEof
fuzzerBestIndex
fuzzerUpdate
fuzzer_register
register_fuzzer_module
Sqlitetestfuzzer_Init
/*
** 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 demonstartion 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 temp.f USING fuzzer;
**
** The name of the new virtual table in the example above is "f".
** Note that all fuzzer virtual tables must be TEMP tables.  The
** "temp." prefix in front of the table name is required when the
** table is being created.  The "temp." prefix can be omitted when
** using the table as long as the name is unambiguous.
**
** Before being used, the fuzzer needs to be programmed by giving it
** character transformations and a cost associated with each transformation.
** Examples:
**
**    INSERT INTO f(cFrom,cTo,Cost) VALUES('','a',100);
**
** The above statement says 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.)
**
**    INSERT INTO f(cFrom,cTo,Cost) VALUES('b','',87);
**
** The above statement says that the cost of deleting a single letter
** 'b' is 87.
**
**    INSERT INTO f(cFrom,cTo,Cost) VALUES('o','oe',38);
**    INSERT INTO f(cFrom,cTo,Cost) VALUES('oe','o',40);
**
** This third example says that the cost of transforming the single
** letter "o" into the two-letter sequence "oe" is 38 and that the
** cost of transforming "oe" back into "o" is 40.
**
** After all the transformation costs have been set, 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.
**
** 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.
*/
#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;

/*
** Type of the "cost" of an edit operation.  Might be changed to
** "float" or "double" or "sqlite3_int64" in the future.
*/
typedef int fuzzer_cost;


/*
** 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 */
  fuzzer_cost rCost;         /* Cost of this transformation */
  int nFrom, nTo;            /* Length of the zFrom and zTo strings */
  char *zFrom;               /* Transform from */
  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 */
  int nBasis;                /* Length of the zBasis string */
  const fuzzer_rule *pRule;  /* Current rule to apply */
  int n;                     /* Apply pRule at this character offset */
  fuzzer_cost rBaseCost;     /* Base cost of getting to zBasis */
  fuzzer_cost rCostX;        /* Precomputed rBaseCost + pRule->rCost */
  fuzzer_stem *pNext;        /* Next stem in rCost order */
  fuzzer_stem *pHash;        /* Next stem with same hash on zBasis */
};

/* 
** 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 */
  fuzzer_rule *pNewRule;     /* New rules to add when last cursor expires */
  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 */
  fuzzer_rule nullRule;      /* Null rule used first */
  fuzzer_stem *apHash[FUZZER_HASH]; /* Hash of previously generated terms */
};

/* Methods for the fuzzer module */
static int fuzzerConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  fuzzer_vtab *pNew;
  int n;
  if( strcmp(argv[1],"temp")!=0 ){
    *pzErr = sqlite3_mprintf("%s virtual tables must be TEMP", argv[0]);
    return SQLITE_ERROR;
  }
  n = strlen(argv[0]) + 1;
  pNew = sqlite3_malloc( sizeof(*pNew) + n );
  if( pNew==0 ) return SQLITE_NOMEM;
  pNew->zClassName = (char*)&pNew[1];
  memcpy(pNew->zClassName, argv[0], n);
  sqlite3_declare_vtab(db, "CREATE TABLE x(word,distance,cFrom,cTo,cost)");
  memset(pNew, 0, sizeof(*pNew));
  *ppVtab = &pNew->base;
  return SQLITE_OK;
}
/* Note that for this virtual table, the xCreate and xConnect
** methods are identical. */

static int fuzzerDisconnect(sqlite3_vtab *pVtab){
  fuzzer_vtab *p = (fuzzer_vtab*)pVtab;
  assert( p->nCursor==0 );
  do{
    while( p->pRule ){
      fuzzer_rule *pRule = p->pRule;
      p->pRule = pRule->pNext;
      sqlite3_free(pRule);
    }
    p->pRule = p->pNewRule;
    p->pNewRule = 0;
  }while( p->pRule );
  sqlite3_free(p);
  return SQLITE_OK;
}
/* The xDisconnect and xDestroy methods are also the same */

/*
** 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;
}


/*
** 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;
  if( p->nCursor==0 && p->pNewRule ){
    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 = p->pNewRule)!=0 ){
      p->pNewRule = 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);
  }
  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;
  char *z;

  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);
  }
  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;
}

/*
** 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 ){
    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;
    pStem->pRule = pRule->pNext;
    if( pStem->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;
  unsigned int h;

  pNew = sqlite3_malloc( sizeof(*pNew) + strlen(zWord) + 1 );
  if( pNew==0 ) return 0;
  memset(pNew, 0, sizeof(*pNew));
  pNew->zBasis = (char*)&pNew[1];
  pNew->nBasis = strlen(zWord);
  memcpy(pNew->zBasis, zWord, pNew->nBasis+1);
  pNew->pRule = pCur->pVtab->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 ){
    if( fuzzerAdvance(pCur, pStem) ){
      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 = 0;
  fuzzer_stem *pStem;

  fuzzerClearCursor(pCur, 1);
  pCur->rLimit = 2147483647;
  if( idxNum==1 ){
    zWord = (const char*)sqlite3_value_text(argv[0]);
  }else if( idxNum==2 ){
    pCur->rLimit = (fuzzer_cost)sqlite3_value_int(argv[0]);
  }else if( idxNum==3 ){
    zWord = (const char*)sqlite3_value_text(argv[0]);
    pCur->rLimit = (fuzzer_cost)sqlite3_value_int(argv[1]);
  }
  if( zWord==0 ) zWord = "";
  pCur->pStem = pStem = fuzzerNewStem(pCur, zWord, (fuzzer_cost)0);
  if( pStem==0 ) return SQLITE_NOMEM;
  pCur->nullRule.pNext = pCur->pVtab->pRule;
  pCur->nullRule.rCost = 0;
  pCur->nullRule.nFrom = 0;
  pCur->nullRule.nTo = 0;
  pCur->nullRule.zFrom = "";
  pStem->pRule = &pCur->nullRule;
  pStem->n = pStem->nBasis;
  pCur->iRowid = 1;
  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:
**
**       word MATCH $str
**       distance < $value
**       distance <= $value
**
** The distance< and distance<= are both treated as distance<=.
** The query plan number is as follows:
**
**   0:    None of the terms above are found
**   1:    There is a "word MATCH" term with $str in filter.argv[0].
**   2:    There is a "distance<" term with $value in filter.argv[0].
**   3:    Both "word MATCH" and "distance<" with $str in argv[0] and
**         $value in argv[1].
*/
static int fuzzerBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  int iPlan = 0;
  int iDistTerm = -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==2 ){
    pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = 1;
  }else if( iPlan==3 ){
    pIdxInfo->aConstraintUsage[iDistTerm].argvIndex = 2;
  }
  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;
}

/*
** Disallow all attempts to DELETE or UPDATE.  Only INSERTs are allowed.
**
** On an insert, the cFrom, cTo, and cost columns are used to construct
** a new rule.   All other columns are ignored.  The rule is ignored
** if cFrom and cTo are identical.  A NULL value for cFrom or cTo is
** interpreted as an empty string.  The cost must be positive.
*/
static int fuzzerUpdate(
  sqlite3_vtab *pVTab,
  int argc,
  sqlite3_value **argv,
  sqlite_int64 *pRowid
){
  fuzzer_vtab *p = (fuzzer_vtab*)pVTab;
  fuzzer_rule *pRule;
  const char *zFrom;
  int nFrom;
  const char *zTo;
  int nTo;
  fuzzer_cost rCost;
  if( argc!=7 ){
    sqlite3_free(pVTab->zErrMsg);
    pVTab->zErrMsg = sqlite3_mprintf("cannot delete from a %s virtual table",
                                     p->zClassName);
    return SQLITE_CONSTRAINT;
  }
  if( sqlite3_value_type(argv[0])!=SQLITE_NULL ){
    sqlite3_free(pVTab->zErrMsg);
    pVTab->zErrMsg = sqlite3_mprintf("cannot update a %s virtual table",
                                     p->zClassName);
    return SQLITE_CONSTRAINT;
  }
  zFrom = (char*)sqlite3_value_text(argv[4]);
  if( zFrom==0 ) zFrom = "";
  zTo = (char*)sqlite3_value_text(argv[5]);
  if( zTo==0 ) zTo = "";
  if( strcmp(zFrom,zTo)==0 ){
    /* Silently ignore null transformations */
    return SQLITE_OK;
  }
  rCost = sqlite3_value_int(argv[6]);
  if( rCost<=0 ){
    sqlite3_free(pVTab->zErrMsg);
    pVTab->zErrMsg = sqlite3_mprintf("cost must be positive");
    return SQLITE_CONSTRAINT;    
  }
  nFrom = strlen(zFrom);
  nTo = strlen(zTo);
  pRule = sqlite3_malloc( sizeof(*pRule) + nFrom + nTo );
  if( pRule==0 ){
    return SQLITE_NOMEM;
  }
  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 = rCost;
  pRule->pNext = p->pNewRule;
  p->pNewRule = pRule;
  return SQLITE_OK;
}

/*
** A virtual table module that provides read-only access to a
** Tcl global variable namespace.
*/
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 */
  fuzzerUpdate,                /* xUpdate - INSERT */
  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;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  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 */
/* [<][>][^][v][top][bottom][index][help] */
root/third_party/sqlite/src/src/test_fuzzer.c

DEFINITIONS
