SQLite

  char const *zDb;                /* Name of database (e.g. "main") */
  char const *zFts3;              /* Name of fts3 table */
  int nDb;                        /* Result of strlen(zDb) */
  int nFts3;                      /* Result of strlen(zFts3) */
  int nByte;                      /* Bytes of space to allocate here */
  int rc;                         /* value returned by declare_vtab() */
  Fts3auxTable *p;                /* Virtual table object to return */



  /* The user should specify a single argument - the name of an fts3 table. */
  if( argc!=4 ){
    *pzErr = sqlite3_mprintf(
        "wrong number of arguments to fts4aux constructor"
    );
    return SQLITE_ERROR;

  sqlite3_vtab *pVTab, 
  sqlite3_index_info *pInfo
){
  int i;
  int iEq = -1;
  int iGe = -1;
  int iLe = -1;



  /* This vtab delivers always results in "ORDER BY term ASC" order. */
  if( pInfo->nOrderBy==1 
   && pInfo->aOrderBy[0].iColumn==0 
   && pInfo->aOrderBy[0].desc==0
  ){
    pInfo->orderByConsumed = 1;

}

/*
** xOpen - Open a cursor.
*/
static int fts3auxOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
  Fts3auxCursor *pCsr;            /* Pointer to cursor object to return */



  pCsr = (Fts3auxCursor *)sqlite3_malloc(sizeof(Fts3auxCursor));
  if( !pCsr ) return SQLITE_NOMEM;
  memset(pCsr, 0, sizeof(Fts3auxCursor));

  *ppCsr = (sqlite3_vtab_cursor *)pCsr;
  return SQLITE_OK;

  int nVal,                       /* Number of elements in apVal */
  sqlite3_value **apVal           /* Arguments for the indexing scheme */
){
  Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
  Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
  int rc;
  int isScan;



  assert( idxStr==0 );
  assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0
       || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT
       || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT)
  );
  isScan = (idxNum!=FTS4AUX_EQ_CONSTRAINT);

**     uregex_close()
*/
static void icuRegexpFunc(sqlite3_context *p, int nArg, sqlite3_value **apArg){
  UErrorCode status = U_ZERO_ERROR;
  URegularExpression *pExpr;
  UBool res;
  const UChar *zString = sqlite3_value_text16(apArg[1]);



  /* If the left hand side of the regexp operator is NULL, 
  ** then the result is also NULL. 
  */
  if( !zString ){
    return;
  }

    {"icu_load_collation",  2, SQLITE_UTF8, (void*)db, icuLoadCollation},
  };

  int rc = SQLITE_OK;
  int i;

  for(i=0; rc==SQLITE_OK && i<(sizeof(scalars)/sizeof(struct IcuScalar)); i++){
    struct IcuScalar *p = &scalars[i];
    rc = sqlite3_create_function(
        db, p->zName, p->nArg, p->enc, p->pContext, p->xFunc, 0, 0
    );
  }

  return rc;

    if( argc>0 ){
      pCsr->aConstraint = sqlite3_malloc(sizeof(RtreeConstraint)*argc);
      pCsr->nConstraint = argc;
      if( !pCsr->aConstraint ){
        rc = SQLITE_NOMEM;
      }else{
        memset(pCsr->aConstraint, 0, sizeof(RtreeConstraint)*argc);
        assert( (idxStr==0 && argc==0) || strlen(idxStr)==argc*2 );
        for(ii=0; ii<argc; ii++){
          RtreeConstraint *p = &pCsr->aConstraint[ii];
          p->op = idxStr[ii*2];
          p->iCoord = idxStr[ii*2+1]-'a';
          if( p->op==RTREE_MATCH ){
            /* A MATCH operator. The right-hand-side must be a blob that
            ** can be cast into an RtreeMatchArg object. One created using

  int iIdx = 0;
  char zIdxStr[RTREE_MAX_DIMENSIONS*8+1];
  memset(zIdxStr, 0, sizeof(zIdxStr));
  UNUSED_PARAMETER(tab);

  assert( pIdxInfo->idxStr==0 );
  for(ii=0; ii<pIdxInfo->nConstraint && iIdx<(sizeof(zIdxStr)-1); ii++){
    struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[ii];

    if( p->usable && p->iColumn==0 && p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
      /* We have an equality constraint on the rowid. Use strategy 1. */
      int jj;
      for(jj=0; jj<ii; jj++){
        pIdxInfo->aConstraintUsage[jj].argvIndex = 0;

static void unlockBtreeMutex(Btree *p){
  BtShared *pBt = p->pBt;
  assert( p->locked==1 );
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3_mutex_held(p->db->mutex) );
  assert( p->db==pBt->db );

  pBt->iMutexCounter++;
  sqlite3_mutex_leave(pBt->mutex);
  p->locked = 0;
}

#ifdef SQLITE_DEBUG
/*
** Return the number of times that the mutex has been exited for
** the given btree.
**
** This is a small circular counter that wraps around to zero on
** overflow.  It is used only for sanity checking - to verify that
** mutexes are held continously by asserting that the value of
** this counter at the beginning of a region is the same as at
** the end.
*/
u32 sqlite3BtreeMutexCounter(Btree *p){
  assert( p->locked==1 || p->sharable==0 );
  return p->pBt->iMutexCounter;
}
#endif

/*
** Enter a mutex on the given BTree object.
**
** If the object is not sharable, then no mutex is ever required
** and this routine is a no-op.  The underlying mutex is non-recursive.
** But we keep a reference count in Btree.wantToLock so the behavior
** of this interface is recursive.

  ** should already be set correctly. */
  assert( (p->locked==0 && p->sharable) || p->pBt->db==p->db );

  if( !p->sharable ) return;
  p->wantToLock++;
  if( p->locked ) return;

  /* Increment the mutex counter on all locked btrees in the same
  ** database connection.  This simulates the unlocking that would
  ** occur on a worst-case mutex dead-lock avoidance scenario.
  */
#ifdef SQLITE_DEBUG
  {
    int ii;
    sqlite3 *db = p->db;
    Btree *pOther;
    for(ii=0; ii<db->nDb; ii++){
      if( ii==1 ) continue;
      pOther = db->aDb[ii].pBt;
      if( pOther==0 || pOther->sharable==0 || pOther->locked==0 ) continue;
      pOther->pBt->iMutexCounter++;
    }
  }
#endif

  /* In most cases, we should be able to acquire the lock we
  ** want without having to go throught the ascending lock
  ** procedure that follows.  Just be sure not to block.
  */
  if( sqlite3_mutex_try(p->pBt->mutex)==SQLITE_OK ){
    p->pBt->db = p->db;
    p->locked = 1;

** Enter the mutexes in accending order by BtShared pointer address
** to avoid the possibility of deadlock when two threads with
** two or more btrees in common both try to lock all their btrees
** at the same instant.
*/
void sqlite3BtreeEnterAll(sqlite3 *db){
  int i;
  Btree *p, *pLater;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    assert( !p || (p->locked==0 && p->sharable) || p->pBt->db==p->db );
    if( p && p->sharable ){
      p->wantToLock++;
      if( !p->locked ){
        assert( p->wantToLock==1 );
        while( p->pPrev ) p = p->pPrev;
        /* Reason for ALWAYS:  There must be at least one unlocked Btree in
        ** the chain.  Otherwise the !p->locked test above would have failed */
        while( p->locked && ALWAYS(p->pNext) ) p = p->pNext;
        for(pLater = p->pNext; pLater; pLater=pLater->pNext){
          if( pLater->locked ){
            unlockBtreeMutex(pLater);
          }
        }
        while( p ){
          lockBtreeMutex(p);
          p = p->pNext;
        }
      }
    }
  }
}
void sqlite3BtreeLeaveAll(sqlite3 *db){
  int i;
  Btree *p;
  assert( sqlite3_mutex_held(db->mutex) );
  for(i=0; i<db->nDb; i++){
    p = db->aDb[i].pBt;
    if( p && p->sharable ){
      assert( p->wantToLock>0 );
      p->wantToLock--;
      if( p->wantToLock==0 ){
        unlockBtreeMutex(p);
      }
    }
  }
}

#ifndef NDEBUG
/*
** Return true if the current thread holds the database connection
** mutex and all required BtShared mutexes.

  ** and the cell content area.  The btreeInitPage() call has already
  ** validated the freelist.  Given that the freelist is valid, there
  ** is no way that the allocation can extend off the end of the page.
  ** The assert() below verifies the previous sentence.
  */
  top -= nByte;
  put2byte(&data[hdr+5], top);
  assert( top+nByte <= pPage->pBt->usableSize );
  *pIdx = top;
  return SQLITE_OK;
}

/*
** Return a section of the pPage->aData to the freelist.
** The first byte of the new free block is pPage->aDisk[start]
** and the size of the block is "size" bytes.
**
** Most of the effort here is involved in coalesing adjacent
** free blocks into a single big free block.
*/
static int freeSpace(MemPage *pPage, int start, int size){
  int addr, pbegin, hdr;
  int iLast;                        /* Largest possible freeblock offset */
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+pPage->childPtrSize );
  assert( (start + size)<=pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( size>=0 );   /* Minimum cell size is 4 */

  if( pPage->pBt->secureDelete ){
    /* Overwrite deleted information with zeros when the secure_delete
    ** option is enabled */
    memset(&data[start], 0, size);

  pPage->nFree = pPage->nFree + (u16)size;

  /* Coalesce adjacent free blocks */
  addr = hdr + 1;
  while( (pbegin = get2byte(&data[addr]))>0 ){
    int pnext, psize, x;
    assert( pbegin>addr );
    assert( pbegin<=pPage->pBt->usableSize-4 );
    pnext = get2byte(&data[pbegin]);
    psize = get2byte(&data[pbegin+2]);
    if( pbegin + psize + 3 >= pnext && pnext>0 ){
      int frag = pnext - (pbegin+psize);
      if( (frag<0) || (frag>(int)data[hdr+7]) ){
        return SQLITE_CORRUPT_BKPT;
      }

    end = cellOffset + 2*pPage->nCell;
    ins = cellOffset + 2*i;
    rc = allocateSpace(pPage, sz, &idx);
    if( rc ){ *pRC = rc; return; }
    /* The allocateSpace() routine guarantees the following two properties
    ** if it returns success */
    assert( idx >= end+2 );
    assert( idx+sz <= pPage->pBt->usableSize );
    pPage->nCell++;
    pPage->nFree -= (u16)(2 + sz);
    memcpy(&data[idx+nSkip], pCell+nSkip, sz-nSkip);
    if( iChild ){
      put4byte(&data[idx], iChild);
    }
    for(j=end, ptr=&data[j]; j>ins; j-=2, ptr-=2){

  int cellbody;     /* Address of next cell body */
  u8 * const data = pPage->aData;             /* Pointer to data for pPage */
  const int hdr = pPage->hdrOffset;           /* Offset of header on pPage */
  const int nUsable = pPage->pBt->usableSize; /* Usable size of page */

  assert( pPage->nOverflow==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( nCell>=0 && nCell<=MX_CELL(pPage->pBt) && MX_CELL(pPage->pBt)<=10921);

  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  /* Check that the page has just been zeroed by zeroPage() */
  assert( pPage->nCell==0 );
  assert( get2byteNotZero(&data[hdr+5])==nUsable );

  pCellptr = &data[pPage->cellOffset + nCell*2];

    int const iToHdr = ((pTo->pgno==1) ? 100 : 0);
    int rc;
    int iData;
  
  
    assert( pFrom->isInit );
    assert( pFrom->nFree>=iToHdr );
    assert( get2byte(&aFrom[iFromHdr+5])<=pBt->usableSize );
  
    /* Copy the b-tree node content from page pFrom to page pTo. */
    iData = get2byte(&aFrom[iFromHdr+5]);
    memcpy(&aTo[iData], &aFrom[iData], pBt->usableSize-iData);
    memcpy(&aTo[iToHdr], &aFrom[iFromHdr], pFrom->cellOffset + 2*pFrom->nCell);
  
    /* Reinitialize page pTo so that the contents of the MemPage structure

      u16 sz = (u16)szNew[i];
      u8 *pTemp;
      assert( nCell<nMaxCells );
      szCell[nCell] = sz;
      pTemp = &aSpace1[iSpace1];
      iSpace1 += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iSpace1<=pBt->pageSize );
      memcpy(pTemp, apDiv[i], sz);
      apCell[nCell] = pTemp+leafCorrection;
      assert( leafCorrection==0 || leafCorrection==4 );
      szCell[nCell] = szCell[nCell] - leafCorrection;
      if( !pOld->leaf ){
        assert( leafCorrection==0 );
        assert( pOld->hdrOffset==0 );

        if( szCell[j]==4 ){
          assert(leafCorrection==4);
          sz = cellSizePtr(pParent, pCell);
        }
      }
      iOvflSpace += sz;
      assert( sz<=pBt->maxLocal+23 );
      assert( iOvflSpace<=pBt->pageSize );
      insertCell(pParent, nxDiv, pCell, sz, pTemp, pNew->pgno, &rc);
      if( rc!=SQLITE_OK ) goto balance_cleanup;
      assert( sqlite3PagerIswriteable(pParent->pDbPage) );

      j++;
      nxDiv++;
    }

  assert( pPage->isInit );
  allocateTempSpace(pBt);
  newCell = pBt->pTmpSpace;
  if( newCell==0 ) return SQLITE_NOMEM;
  rc = fillInCell(pPage, newCell, pKey, nKey, pData, nData, nZero, &szNew);
  if( rc ) goto end_insert;
  assert( szNew==cellSizePtr(pPage, newCell) );
  assert( szNew<=MX_CELL_SIZE(pBt) );
  idx = pCur->aiIdx[pCur->iPage];
  if( loc==0 ){
    u16 szOld;
    assert( idx<pPage->nCell );
    rc = sqlite3PagerWrite(pPage->pDbPage);
    if( rc ){
      goto end_insert;

    MemPage *pLeaf = pCur->apPage[pCur->iPage];
    int nCell;
    Pgno n = pCur->apPage[iCellDepth+1]->pgno;
    unsigned char *pTmp;

    pCell = findCell(pLeaf, pLeaf->nCell-1);
    nCell = cellSizePtr(pLeaf, pCell);
    assert( MX_CELL_SIZE(pBt)>=nCell );

    allocateTempSpace(pBt);
    pTmp = pBt->pTmpSpace;

    rc = sqlite3PagerWrite(pLeaf->pDbPage);
    insertCell(pPage, iCellIdx, pCell-4, nCell+4, pTmp, n, &rc);
    dropCell(pLeaf, pLeaf->nCell-1, nCell, &rc);

  void sqlite3BtreeLeaveCursor(BtCursor*);
  void sqlite3BtreeLeaveAll(sqlite3*);
#ifndef NDEBUG
  /* These routines are used inside assert() statements only. */
  int sqlite3BtreeHoldsMutex(Btree*);
  int sqlite3BtreeHoldsAllMutexes(sqlite3*);
  int sqlite3SchemaMutexHeld(sqlite3*,int,Schema*);
  u32 sqlite3BtreeMutexCounter(Btree*);
#endif
#else

# define sqlite3BtreeLeave(X)
# define sqlite3BtreeMutexCounter(X) 0
# define sqlite3BtreeEnterCursor(X)
# define sqlite3BtreeLeaveCursor(X)
# define sqlite3BtreeLeaveAll(X)

# define sqlite3BtreeHoldsMutex(X) 1
# define sqlite3BtreeHoldsAllMutexes(X) 1
# define sqlite3BtreeSchemaMutexHeld(X,Y) 1
#endif


#endif /* _BTREE_H_ */

*/
#include "sqliteInt.h"


/* The following value is the maximum cell size assuming a maximum page
** size give above.
*/
#define MX_CELL_SIZE(pBt)  (pBt->pageSize-8)

/* The maximum number of cells on a single page of the database.  This
** assumes a minimum cell size of 6 bytes  (4 bytes for the cell itself
** plus 2 bytes for the index to the cell in the page header).  Such
** small cells will be rare, but they are possible.
*/
#define MX_CELL(pBt) ((pBt->pageSize-8)/6)

#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */
  BtLock *pLock;        /* List of locks held on this shared-btree struct */
  Btree *pWriter;       /* Btree with currently open write transaction */
  u8 isExclusive;       /* True if pWriter has an EXCLUSIVE lock on the db */
  u8 isPending;         /* If waiting for read-locks to clear */
  u16 iMutexCounter;    /* The number of mutex_leave(mutex) calls */
#endif
  u8 *pTmpSpace;        /* BtShared.pageSize bytes of space for tmp use */
};

/*
** An instance of the following structure is used to hold information
** about a cell.  The parseCellPtr() function fills in this structure

  int i, j;
  assert( iDb<db->nDb );

  if( iDb>=0 ){
    /* Case 1:  Reset the single schema identified by iDb */
    Db *pDb = &db->aDb[iDb];
    assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
    if( ALWAYS(pDb->pSchema) ){
      sqlite3SchemaClear(pDb->pSchema);
    }
    /* If any database other than TEMP is reset, then also reset TEMP
    ** since TEMP might be holding triggers that reference tables in the
    ** other database.
    */

    if( iDb!=1 && (pDb = &db->aDb[1])!=0 && ALWAYS(pDb->pSchema) ){

      sqlite3SchemaClear(pDb->pSchema);
    }
    return;
  }
  /* Case 2 (from here to the end): Reset all schemas for all attached
  ** databases. */
  assert( iDb<0 );

    const char *zType;

    sqlite3_snprintf(n-k, &zStmt[k], zSep);
    k += sqlite3Strlen30(&zStmt[k]);
    zSep = zSep2;
    identPut(zStmt, &k, pCol->zName);
    assert( pCol->affinity-SQLITE_AFF_TEXT >= 0 );
    assert( pCol->affinity-SQLITE_AFF_TEXT < sizeof(azType)/sizeof(azType[0]) );
    testcase( pCol->affinity==SQLITE_AFF_TEXT );
    testcase( pCol->affinity==SQLITE_AFF_NONE );
    testcase( pCol->affinity==SQLITE_AFF_NUMERIC );
    testcase( pCol->affinity==SQLITE_AFF_INTEGER );
    testcase( pCol->affinity==SQLITE_AFF_REAL );
    
    zType = azType[pCol->affinity - SQLITE_AFF_TEXT];

 int count                /* Number of times table has been busy */
){
#if SQLITE_OS_WIN || (defined(HAVE_USLEEP) && HAVE_USLEEP)
  static const u8 delays[] =
     { 1, 2, 5, 10, 15, 20, 25, 25,  25,  50,  50, 100 };
  static const u8 totals[] =
     { 0, 1, 3,  8, 18, 33, 53, 78, 103, 128, 178, 228 };
# define NDELAY (sizeof(delays)/sizeof(delays[0]))
  sqlite3 *db = (sqlite3 *)ptr;
  int timeout = db->busyTimeout;
  int delay, prior;

  assert( count>=0 );
  if( count < NDELAY ){
    delay = delays[count];

      /* Release memory from the SQLITE_CONFIG_SCRATCH allocation */
      ScratchFreeslot *pSlot;
      pSlot = (ScratchFreeslot*)p;
      sqlite3_mutex_enter(mem0.mutex);
      pSlot->pNext = mem0.pScratchFree;
      mem0.pScratchFree = pSlot;
      mem0.nScratchFree++;
      assert( mem0.nScratchFree<=sqlite3GlobalConfig.nScratch );
      sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_USED, -1);
      sqlite3_mutex_leave(mem0.mutex);
    }else{
      /* Release memory back to the heap */
      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
      assert( sqlite3MemdebugNoType(p, ~MEMTYPE_SCRATCH) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);

  /*
  ** Space for tracking which blocks are checked out and the size
  ** of each block.  One byte per block.
  */
  u8 *aCtrl;

} mem5 = { 0 };

/*
** Access the static variable through a macro for SQLITE_OMIT_WSD
*/
#define mem5 GLOBAL(struct Mem5Global, mem5)

/*

**             memsys5Log(4) -> 2
**             memsys5Log(5) -> 3
**             memsys5Log(8) -> 3
**             memsys5Log(9) -> 4
*/
static int memsys5Log(int iValue){
  int iLog;
  for(iLog=0; (iLog<((sizeof(int)*8)-1)) && (1<<iLog)<iValue; iLog++);
  return iLog;
}

/*
** Initialize the memory allocator.
**
** This routine is not threadsafe.  The caller must be holding a mutex

  assert( pPager->pWal );
#ifdef SQLITE_DEBUG
  /* Verify that the page list is in accending order */
  for(p=pList; p && p->pDirty; p=p->pDirty){
    assert( p->pgno < p->pDirty->pgno );
  }
#endif














  if( pList->pgno==1 ) pager_write_changecounter(pList);
  rc = sqlite3WalFrames(pPager->pWal, 
      pPager->pageSize, pList, nTruncate, isCommit, syncFlags
  );
  if( rc==SQLITE_OK && pPager->pBackup ){
    PgHdr *p;
    for(p=pList; p; p=p->pDirty){
      sqlite3BackupUpdate(pPager->pBackup, p->pgno, (u8 *)p->pData);
    }
  }

#ifdef SQLITE_CHECK_PAGES

  for(p=pList; p; p=p->pDirty){
    pager_set_pagehash(p);
  }
#endif

  return rc;
}

    int rc = 0;
    int i, n;
    open_db(p);

    /* convert testctrl text option to value. allow any unique prefix
    ** of the option name, or a numerical value. */
    n = strlen(azArg[1]);
    for(i=0; i<sizeof(aCtrl)/sizeof(aCtrl[0]); i++){
      if( strncmp(azArg[1], aCtrl[i].zCtrlName, n)==0 ){
        if( testctrl<0 ){
          testctrl = aCtrl[i].ctrlCode;
        }else{
          fprintf(stderr, "ambiguous option name: \"%s\"\n", azArg[i]);
          testctrl = -1;
          break;

**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** [SQLITE_DBCONIG_LOOKASIDE | configuration verb] - an integer code 
** that indicates what aspect of the [database connection] is being configured.
** Subsequent arguments vary depending on the configuration verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
int sqlite3_db_config(sqlite3*, int op, ...);

  if( ctx.pFunc->flags & SQLITE_FUNC_NEEDCOLL ){
    assert( pOp>aOp );
    assert( pOp[-1].p4type==P4_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    ctx.pColl = pOp[-1].p4.pColl;
  }
  (*ctx.pFunc->xFunc)(&ctx, n, apVal); /* IMP: R-24505-23230 */
  sqlite3VdbeMutexResync(p);
  if( db->mallocFailed ){
    /* Even though a malloc() has failed, the implementation of the
    ** user function may have called an sqlite3_result_XXX() function
    ** to return a value. The following call releases any resources
    ** associated with such a value.
    */
    sqlite3VdbeMemRelease(&ctx.s);

          if( rc!=SQLITE_OK ){
            goto abort_due_to_error;
          }
        }
        if( p1==SAVEPOINT_ROLLBACK && (db->flags&SQLITE_InternChanges)!=0 ){
          sqlite3ExpirePreparedStatements(db);
          sqlite3ResetInternalSchema(db, -1);
          sqlite3VdbeMutexResync(p);
          db->flags = (db->flags | SQLITE_InternChanges);
        }
      }
  
      /* Regardless of whether this is a RELEASE or ROLLBACK, destroy all 
      ** savepoints nested inside of the savepoint being operated on. */
      while( db->pSavepoint!=pSavepoint ){

  assert( (p->btreeMask & (((yDbMask)1)<<pOp->p1))!=0 );
  assert( sqlite3SchemaMutexHeld(db, pOp->p1, 0) );
  pBt = db->aDb[pOp->p1].pBt;
  if( pBt ){
    sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&iMeta);
    iGen = db->aDb[pOp->p1].pSchema->iGeneration;
  }else{
    iMeta = 0;
  }
  if( iMeta!=pOp->p2 || iGen!=pOp->p3 ){
    sqlite3DbFree(db, p->zErrMsg);
    p->zErrMsg = sqlite3DbStrDup(db, "database schema has changed");
    /* If the schema-cookie from the database file matches the cookie 
    ** stored with the in-memory representation of the schema, do
    ** not reload the schema from the database file.

  if( ctx.pFunc->flags & SQLITE_FUNC_NEEDCOLL ){
    assert( pOp>p->aOp );
    assert( pOp[-1].p4type==P4_COLLSEQ );
    assert( pOp[-1].opcode==OP_CollSeq );
    ctx.pColl = pOp[-1].p4.pColl;
  }
  (ctx.pFunc->xStep)(&ctx, n, apVal); /* IMP: R-24505-23230 */
  sqlite3VdbeMutexResync(p);
  if( ctx.isError ){
    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(&ctx.s));
    rc = ctx.isError;
  }

  /* The app-defined function has done something that as caused this
  ** statement to expire.  (Perhaps the function called sqlite3_exec()
  ** with a CREATE TABLE statement.)
  */
#if 0
  if( p->expired ){
    rc = SQLITE_ABORT;
    break;
  }
#endif

  sqlite3VdbeMemRelease(&ctx.s);

  break;
}

/* Opcode: AggFinal P1 P2 * P4 *
**

*/
case OP_AggFinal: {
  Mem *pMem;
  assert( pOp->p1>0 && pOp->p1<=p->nMem );
  pMem = &aMem[pOp->p1];
  assert( (pMem->flags & ~(MEM_Null|MEM_Agg))==0 );
  rc = sqlite3VdbeMemFinalize(pMem, pOp->p4.pFunc);
  sqlite3VdbeMutexResync(p);
  if( rc ){
    sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3_value_text(pMem));
  }else if( p->expired ){
    rc = SQLITE_ABORT;
  }
  sqlite3VdbeChangeEncoding(pMem, encoding);
  UPDATE_MAX_BLOBSIZE(pMem);
  if( sqlite3VdbeMemTooBig(pMem) ){
    goto too_big;
  }
  break;

       || eNew==PAGER_JOURNALMODE_OFF
       || eNew==PAGER_JOURNALMODE_MEMORY
       || eNew==PAGER_JOURNALMODE_WAL
       || eNew==PAGER_JOURNALMODE_QUERY
  );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );

  /* This opcode is used in two places: PRAGMA journal_mode and ATTACH.
  ** In PRAGMA journal_mode, the sqlite3VdbeUsesBtree() routine is called
  ** when the statement is prepared and so p->btreeMask!=0.  All mutexes
  ** are already acquired.  But when used in ATTACH, sqlite3VdbeUsesBtree()
  ** is not called when the statement is prepared because it requires the
  ** iDb index of the database as a parameter, and the database has not
  ** yet been attached so that index is unavailable.  We have to wait
  ** until runtime (now) to get the mutex on the newly attached database.
  ** No other mutexes are required by the ATTACH command so this is safe
  ** to do.
  */
  if( p->btreeMask==0 ){
    /* This occurs right after ATTACH.  Get a mutex on the newly ATTACHed
    ** database. */
    sqlite3VdbeUsesBtree(p, pOp->p1);
    sqlite3VdbeEnter(p);
  }

  pBt = db->aDb[pOp->p1].pBt;
  pPager = sqlite3BtreePager(pBt);
  eOld = sqlite3PagerGetJournalMode(pPager);
  if( eNew==PAGER_JOURNALMODE_QUERY ) eNew = eOld;
  if( !sqlite3PagerOkToChangeJournalMode(pPager) ) eNew = eOld;

#ifndef SQLITE_OMIT_WAL

  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
  u32 iMutexCounter;      /* Mutex counter upon sqlite3VdbeEnter() */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
#ifndef SQLITE_OMIT_TRACE
  i64 startTime;          /* Time when query started - used for profiling */
#endif
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */

int sqlite3VdbeMemFinalize(Mem*, FuncDef*);
const char *sqlite3OpcodeName(int);
int sqlite3VdbeMemGrow(Mem *pMem, int n, int preserve);
int sqlite3VdbeCloseStatement(Vdbe *, int);
void sqlite3VdbeFrameDelete(VdbeFrame*);
int sqlite3VdbeFrameRestore(VdbeFrame *);
void sqlite3VdbeMemStoreType(Mem *pMem);


void sqlite3VdbeEnter(Vdbe*);
void sqlite3VdbeLeave(Vdbe*);

void sqlite3VdbeMutexResync(Vdbe*);



#ifdef SQLITE_DEBUG
void sqlite3VdbeMemPrepareToChange(Vdbe*,Mem*);
#endif

#ifndef SQLITE_OMIT_FOREIGN_KEY
int sqlite3VdbeCheckFk(Vdbe *, int);

    ** this assert() from failing, when building with SQLITE_DEBUG defined
    ** using gcc, force nullMem to be 8-byte aligned using the magical
    ** __attribute__((aligned(8))) macro.  */
    static const Mem nullMem 
#if defined(SQLITE_DEBUG) && defined(__GNUC__)
      __attribute__((aligned(8))) 
#endif
      = {0, "", (double)0, {0}, 0, MEM_Null, SQLITE_NULL, 0, 0, 0 };





    if( pVm && ALWAYS(pVm->db) ){
      sqlite3_mutex_enter(pVm->db->mutex);
      sqlite3Error(pVm->db, SQLITE_RANGE, 0);
    }
    pOut = (Mem*)&nullMem;
  }

** Declare to the Vdbe that the BTree object at db->aDb[i] is used.
**
** The prepared statements need to know in advance the complete set of
** attached databases that they will be using.  A mask of these databases
** is maintained in p->btreeMask and is used for locking and other purposes.
*/
void sqlite3VdbeUsesBtree(Vdbe *p, int i){
  assert( i>=0 && i<p->db->nDb && i<sizeof(yDbMask)*8 );
  assert( i<(int)sizeof(p->btreeMask)*8 );
  p->btreeMask |= ((yDbMask)1)<<i;
}

/*
** Compute the sum of all mutex counters for all btrees in the
** given prepared statement.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
static u32 mutexCounterSum(Vdbe *p){
  u32 cntSum = 0;
#ifdef SQLITE_DEBUG
  int i;
  yDbMask mask;
  sqlite3 *db = p->db;
  Db *aDb = db->aDb;
  int nDb = db->nDb;
  for(i=0, mask=1; i<nDb; i++, mask += mask){
    if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
      cntSum += sqlite3BtreeMutexCounter(aDb[i].pBt);
    }
  }
#else
  UNUSED_PARAMETER(p);
#endif
  return cntSum;
}
#endif

/*
** If SQLite is compiled to support shared-cache mode and to be threadsafe,
** this routine obtains the mutex associated with each BtShared structure
** that may be accessed by the VM passed as an argument. In doing so it also
** sets the BtShared.db member of each of the BtShared structures, ensuring
** that the correct busy-handler callback is invoked if required.
**

** The p->btreeMask field is a bitmask of all btrees that the prepared 
** statement p will ever use.  Let N be the number of bits in p->btreeMask
** corresponding to btrees that use shared cache.  Then the runtime of
** this routine is N*N.  But as N is rarely more than 1, this should not
** be a problem.
*/
void sqlite3VdbeEnter(Vdbe *p){
#ifndef SQLITE_OMIT_SHARED_CACHE
  int i;
  yDbMask mask;
  sqlite3 *db = p->db;
  Db *aDb = db->aDb;
  int nDb = db->nDb;
  for(i=0, mask=1; i<nDb; i++, mask += mask){
    if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeEnter(aDb[i].pBt);
    }
  }
  p->iMutexCounter = mutexCounterSum(p);
#else
  UNUSED_PARAMETER(p);

#endif
}

/*
** Unlock all of the btrees previously locked by a call to sqlite3VdbeEnter().
*/
void sqlite3VdbeLeave(Vdbe *p){
#ifndef SQLITE_OMIT_SHARED_CACHE
  int i;
  yDbMask mask;
  sqlite3 *db = p->db;
  Db *aDb = db->aDb;
  int nDb = db->nDb;

  /* Assert that the all mutexes have been held continously since
  ** the most recent sqlite3VdbeEnter() or sqlite3VdbeMutexResync().
  */
  assert( mutexCounterSum(p) == p->iMutexCounter );

  for(i=0, mask=1; i<nDb; i++, mask += mask){
    if( i!=1 && (mask & p->btreeMask)!=0 && ALWAYS(aDb[i].pBt!=0) ){
      sqlite3BtreeLeave(aDb[i].pBt);
    }
  }
#else
  UNUSED_PARAMETER(p);
#endif
}

/*
** Recompute the sum of the mutex counters on all btrees used by the
** prepared statement p.
**
** Call this routine while holding a sqlite3VdbeEnter() after doing something
** that might cause one or more of the individual mutexes held by the
** prepared statement to be released.  Calling sqlite3BtreeEnter() on 
** any BtShared mutex which is not used by the prepared statement is one
** way to cause one or more of the mutexes in the prepared statement
** to be temporarily released.  The anti-deadlocking logic in
** sqlite3BtreeEnter() can cause mutexes to be released temporarily then
** reacquired.
**
** Calling this routine is an acknowledgement that some of the individual
** mutexes in the prepared statement might have been released and reacquired.
** So checks to verify that mutex-protected content did not change
** unexpectedly should accompany any call to this routine.
*/
void sqlite3VdbeMutexResync(Vdbe *p){
#if !defined(SQLITE_OMIT_SHARED_CACHE) && defined(SQLITE_DEBUG)
  p->iMutexCounter = mutexCounterSum(p);
#else
  UNUSED_PARAMETER(p);
#endif
}

#if defined(VDBE_PROFILE) || defined(SQLITE_DEBUG)
/*
** Print a single opcode.  This routine is used for debugging only.
*/
void sqlite3VdbePrintOp(FILE *pOut, int pc, Op *pOp){
  char *zP4;

    /* Rollback or commit any schema changes that occurred. */
    if( p->rc!=SQLITE_OK && db->flags&SQLITE_InternChanges ){
      sqlite3ResetInternalSchema(db, -1);
      db->flags = (db->flags | SQLITE_InternChanges);
    }

    /* Release the locks */
    sqlite3VdbeMutexResync(p);
    sqlite3VdbeLeave(p);
  }

  /* We have successfully halted and closed the VM.  Record this fact. */
  if( p->pc>=0 ){
    db->activeVdbeCnt--;
    if( !p->readOnly ){

/*
** Return the bitmask for the given cursor number.  Return 0 if
** iCursor is not in the set.
*/
static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){
  int i;
  assert( pMaskSet->n<=sizeof(Bitmask)*8 );
  for(i=0; i<pMaskSet->n; i++){
    if( pMaskSet->ix[i]==iCursor ){
      return ((Bitmask)1)<<i;
    }
  }
  return 0;
}

#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
source $testdir/malloc_common.tcl
source $testdir/wal_common.tcl



ifcapable !wal {finish_test ; return }
if { ![wal_is_ok] } {
  finish_test 
  return 
}

  execsql { SELECT * FROM t1 }
} {1 2 3 4}
set nPage [expr 2+$AUTOVACUUM]
do_test wal-23.4 { 
  set ::log 
} [list SQLITE_OK "Recovered $nPage frames from WAL file $walfile"]






























db close



















sqlite3_shutdown
test_sqlite3_log
sqlite3_initialize

finish_test