SQLite

/*
** 2004 April 6
**
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.446 2008/03/25 14:24:57 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

  }
#ifndef SQLITE_OMIT_INCRBLOB
  if( pCur->isIncrblobHandle ){
    return SQLITE_ABORT;
  }
#endif
  pCur->eState = CURSOR_INVALID;
  rc = sqlite3BtreeMoveto(pCur, pCur->pKey, pCur->nKey, 0, &pCur->skip);
  if( rc==SQLITE_OK ){
    sqlite3_free(pCur->pKey);
    pCur->pKey = 0;
    assert( pCur->eState==CURSOR_VALID || pCur->eState==CURSOR_INVALID );
  }
  return rc;
}

      *pRes = 0;
      rc = moveToRightmost(pCur);
    }
  }
  return rc;
}

/* Move the cursor so that it points to an entry near pKey/nKey.
** Return a success code.
**
** For INTKEY tables, only the nKey parameter is used.  pKey is
** ignored.  For other tables, nKey is the number of bytes of data

** in pKey.
**
** If an exact match is not found, then the cursor is always
** left pointing at a leaf page which would hold the entry if it
** were present.  The cursor might point to an entry that comes
** before or after the key.
**
** The result of comparing the key with the entry to which the

**     *pRes>0      The cursor is left pointing at an entry that
**                  is larger than pKey.
**
*/
int sqlite3BtreeMoveto(
  BtCursor *pCur,        /* The cursor to be moved */
  const void *pKey,      /* The key content for indices.  Not used by tables */

  i64 nKey,              /* Size of pKey.  Or the key for tables */
  int biasRight,         /* If true, bias the search to the high end */
  int *pRes              /* Search result flag */
){
  int rc;
  VdbeParsedRecord *pPKey;
  char aSpace[200];

  assert( cursorHoldsMutex(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  rc = moveToRoot(pCur);
  if( rc ){
    return rc;
  }
  assert( pCur->pPage );
  assert( pCur->pPage->isInit );
  if( pCur->eState==CURSOR_INVALID ){
    *pRes = -1;
    assert( pCur->pPage->nCell==0 );
    return SQLITE_OK;
  }
  if( pCur->pPage->intKey ){



    pPKey = 0;
  }else{




    pPKey = sqlite3VdbeRecordParse(pCur->pKeyInfo, nKey, pKey,
                                   aSpace, sizeof(aSpace));
    if( pPKey==0 ) return SQLITE_NOMEM;




  }
  for(;;){
    int lwr, upr;
    Pgno chldPg;
    MemPage *pPage = pCur->pPage;
    int c = -1;  /* pRes return if table is empty must be -1 */
    lwr = 0;
    upr = pPage->nCell-1;
    if( !pPage->intKey && pKey==0 ){
      rc = SQLITE_CORRUPT_BKPT;
      goto moveto_finish;
    }
    if( biasRight ){
      pCur->idx = upr;
    }else{
      pCur->idx = (upr+lwr)/2;

          c = 0;
        }
      }else{
        int available;
        pCellKey = (void *)fetchPayload(pCur, &available, 0);
        nCellKey = pCur->info.nKey;
        if( available>=nCellKey ){
          c = sqlite3VdbeRecordCompareParsed(nCellKey, pCellKey, pPKey);
        }else{
          pCellKey = sqlite3_malloc( nCellKey );
          if( pCellKey==0 ){
            rc = SQLITE_NOMEM;
            goto moveto_finish;
          }
          rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
          c = sqlite3VdbeRecordCompareParsed(nCellKey, pCellKey, pPKey);
          sqlite3_free(pCellKey);
          if( rc ) goto moveto_finish;
        }
      }
      if( c==0 ){
        if( pPage->leafData && !pPage->leaf ){
          lwr = pCur->idx;

    }
    pCur->idx = lwr;
    pCur->info.nSize = 0;
    rc = moveToChild(pCur, chldPg);
    if( rc ) goto moveto_finish;
  }
moveto_finish:



  sqlite3VdbeRecordUnparse(pPKey);

  return rc;
}


/*
** Return TRUE if the cursor is not pointing at an entry of the table.
**

    return pCur->skip;
  }

  /* Save the positions of any other cursors open on this table */
  clearCursorPosition(pCur);
  if( 
    SQLITE_OK!=(rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur)) ||
    SQLITE_OK!=(rc = sqlite3BtreeMoveto(pCur, pKey, nKey, appendBias, &loc))
  ){
    return rc;
  }

  pPage = pCur->pPage;
  assert( pPage->intKey || nKey>=0 );
  assert( pPage->leaf || !pPage->leafData );

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.96 2008/03/25 09:47:35 danielk1977 Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/

int sqlite3BtreeDropTable(Btree*, int, int*);
int sqlite3BtreeClearTable(Btree*, int);
int sqlite3BtreeGetMeta(Btree*, int idx, u32 *pValue);
int sqlite3BtreeUpdateMeta(Btree*, int idx, u32 value);
void sqlite3BtreeTripAllCursors(Btree*, int);



int sqlite3BtreeCursor(
  Btree*,                              /* BTree containing table to open */
  int iTable,                          /* Index of root page */
  int wrFlag,                          /* 1 for writing.  0 for read-only */
  struct KeyInfo*,                     /* First argument to compare function */
  BtCursor *pCursor                    /* Space to write cursor structure */
);
int sqlite3BtreeCursorSize();

int sqlite3BtreeCloseCursor(BtCursor*);
int sqlite3BtreeMoveto(BtCursor*,const void *pKey,i64 nKey,int bias,int *pRes);







int sqlite3BtreeDelete(BtCursor*);
int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
                                  const void *pData, int nData,
                                  int nZero, int bias);
int sqlite3BtreeFirst(BtCursor*, int *pRes);
int sqlite3BtreeLast(BtCursor*, int *pRes);
int sqlite3BtreeNext(BtCursor*, int *pRes);

**     CREATE INDEX
**     DROP INDEX
**     creating ID lists
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**
** $Id: build.c,v 1.476 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Initialize the pParse structure as needed.

                    (char *)pKey, P4_KEYINFO_HANDOFF);
  if( memRootPage>=0 ){
    sqlite3VdbeChangeP5(v, 1);
  }
  sqlite3OpenTable(pParse, iTab, iDb, pTab, OP_OpenRead);
  addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iTab, 0);
  regRecord = sqlite3GetTempReg(pParse);
  regIdxKey = sqlite3GenerateIndexKey(pParse, pIndex, iTab, regRecord);
  if( pIndex->onError!=OE_None ){
    int j1, j2;
    int regRowid;

    regRowid = regIdxKey + pIndex->nColumn;
    j1 = sqlite3VdbeAddOp3(v, OP_IsNull, regIdxKey, 0, pIndex->nColumn);
    j2 = sqlite3VdbeAddOp4(v, OP_IsUnique, iIdx,

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** in order to generate code for DELETE FROM statements.
**
** $Id: delete.c,v 1.163 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"

/*
** Look up every table that is named in pSrc.  If any table is not found,
** add an error message to pParse->zErrMsg and return NULL.  If all tables
** are found, return a pointer to the last table.

  int iCur,          /* Cursor number for the table */
  int *aRegIdx       /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
){
  int i;
  Index *pIdx;
  int r1;

  r1 = sqlite3GetTempReg(pParse);
  for(i=1, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
    if( aRegIdx!=0 && aRegIdx[i-1]==0 ) continue;
    sqlite3GenerateIndexKey(pParse, pIdx, iCur, r1);
    sqlite3VdbeAddOp2(pParse->pVdbe, OP_IdxDelete, iCur+i, r1);
  }
  sqlite3ReleaseTempReg(pParse, r1);
}

/*
** Generate code that will assemble an index key and put it on the top
** of the tack.  The key with be for index pIdx which is an index on pTab.
** iCur is the index of a cursor open on the pTab table and pointing to
** the entry that needs indexing.
**
** Return a register number which is the first in a block of
** registers that holds the elements of the index key.  The
** block of registers has already been deallocated by the time
** this routine returns.
*/
int sqlite3GenerateIndexKey(
  Parse *pParse,     /* Parsing context */
  Index *pIdx,       /* The index for which to generate a key */
  int iCur,          /* Cursor number for the pIdx->pTable table */
  int regOut         /* Write the new index key to this register */

){
  Vdbe *v = pParse->pVdbe;
  int j;
  Table *pTab = pIdx->pTable;
  int regBase;
  int nCol;

  nCol = pIdx->nColumn;
  regBase = sqlite3GetTempRange(pParse, nCol+1);
  sqlite3VdbeAddOp2(v, OP_Rowid, iCur, regBase+nCol);
  for(j=0; j<nCol; j++){
    int idx = pIdx->aiColumn[j];
    if( idx==pTab->iPKey ){
      sqlite3VdbeAddOp2(v, OP_SCopy, regBase+nCol, regBase+j);
    }else{
      sqlite3VdbeAddOp3(v, OP_Column, iCur, idx, regBase+j);
      sqlite3ColumnDefault(v, pTab, idx);
    }
  }

  sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol+1, regOut);
  sqlite3IndexAffinityStr(v, pIdx);

  sqlite3ReleaseTempRange(pParse, regBase, nCol+1);
  return regBase;
}

/* Make sure "isView" gets undefined in case this file becomes part of
** the amalgamation - so that subsequent files do not see isView as a
** macro. */
#undef isView

/*
** 2003 April 6
**
** 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.
**
*************************************************************************
** This file contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.172 2008/03/20 11:04:21 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/
#if !defined(SQLITE_OMIT_PRAGMA) && !defined(SQLITE_OMIT_PARSER)

            { OP_Concat,      4,  3,  3},
            { OP_Concat,      5,  3,  3},
            { OP_Concat,      6,  3,  3},
            { OP_ResultRow,   3,  1,  0},
            { OP_IfPos,       1,  0,  0},    /* 9 */
            { OP_Halt,        0,  0,  0},
          };
          sqlite3GenerateIndexKey(pParse, pIdx, 1, 3);
          jmp2 = sqlite3VdbeAddOp3(v, OP_Found, j+2, 0, 3);
          addr = sqlite3VdbeAddOpList(v, ArraySize(idxErr), idxErr);
          sqlite3VdbeChangeP4(v, addr+1, "rowid ", P4_STATIC);
          sqlite3VdbeChangeP4(v, addr+3, " missing from index ", P4_STATIC);
          sqlite3VdbeChangeP4(v, addr+4, pIdx->zName, P4_STATIC);
          sqlite3VdbeJumpHere(v, addr+9);
          sqlite3VdbeJumpHere(v, jmp2);

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.418 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"


/*
** Delete all the content of a Select structure but do not deallocate
** the select structure itself.

    }

    /* Construct a record from the query result, but instead of
    ** saving that record, use it as a key to delete elements from
    ** the temporary table iParm.
    */
    case SRT_Except: {
      int r1;
      r1 = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
      sqlite3VdbeChangeP4(v, -1, aff, P4_STATIC);
      sqlite3VdbeAddOp2(v, OP_IdxDelete, iParm, r1);
      sqlite3ReleaseTempReg(pParse, r1);
      break;
    }
#endif

    /* Store the result as data using a unique key.
    */
    case SRT_Table:

/*
** 2001 September 15
**
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.679 2008/03/21 16:45:47 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if it was run
** (otherwise we get an empty default).

int sqlite3ExprIsConstant(Expr*);
int sqlite3ExprIsConstantNotJoin(Expr*);
int sqlite3ExprIsConstantOrFunction(Expr*);
int sqlite3ExprIsInteger(Expr*, int*);
int sqlite3IsRowid(const char*);
void sqlite3GenerateRowDelete(Parse*, Table*, int, int, int);
void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int*);
int sqlite3GenerateIndexKey(Parse*, Index*, int, int);
void sqlite3GenerateConstraintChecks(Parse*,Table*,int,int,
                                     int*,int,int,int,int);
void sqlite3CompleteInsertion(Parse*, Table*, int, int, int*,int,int,int,int);
int sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
void sqlite3BeginWriteOperation(Parse*, int, int);
Expr *sqlite3ExprDup(sqlite3*,Expr*);
void sqlite3TokenCopy(sqlite3*,Token*, Token*);

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the btree.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test3.c,v 1.93 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "btreeInt.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>

  sqlite3BtreeEnter(pCur->pBtree);
  if( sqlite3BtreeFlags(pCur) & BTREE_INTKEY ){
    int iKey;
    if( Tcl_GetInt(interp, argv[2], &iKey) ){
      sqlite3BtreeLeave(pCur->pBtree);
      return TCL_ERROR;
    }
    rc = sqlite3BtreeMoveto(pCur, 0, iKey, 0, &res);
  }else{
    rc = sqlite3BtreeMoveto(pCur, argv[2], strlen(argv[2]), 0, &res);  
  }
  sqlite3BtreeLeave(pCur->pBtree);
  if( rc ){
    Tcl_AppendResult(interp, errorName(rc), 0);
    return TCL_ERROR;
  }
  if( res<0 ) res = -1;

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.717 2008/03/25 09:47:35 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include "vdbeInt.h"

/*
** The following global variable is incremented every time a cursor

      if( pOp->p2==0 ){
        assert( pOp->opcode==OP_MoveGe );
        pC->movetoTarget = iKey;
        pC->rowidIsValid = 0;
        pC->deferredMoveto = 1;
        break;
      }
      rc = sqlite3BtreeMoveto(pC->pCursor, 0, (u64)iKey, 0, &res);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      pC->lastRowid = iKey;
      pC->rowidIsValid = res==0;
    }else{
      assert( pIn3->flags & MEM_Blob );
      ExpandBlob(pIn3);
      rc = sqlite3BtreeMoveto(pC->pCursor, pIn3->z, pIn3->n, 0, &res);
      if( rc!=SQLITE_OK ){
        goto abort_due_to_error;
      }
      pC->rowidIsValid = 0;
    }
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;

  if( (pC = p->apCsr[i])->pCursor!=0 ){
    int res;
    assert( pC->isTable==0 );
    assert( pIn3->flags & MEM_Blob );
    if( pOp->opcode==OP_Found ){
      pC->pKeyInfo->prefixIsEqual = 1;
    }
    rc = sqlite3BtreeMoveto(pC->pCursor, pIn3->z, pIn3->n, 0, &res);
    pC->pKeyInfo->prefixIsEqual = 0;
    if( rc!=SQLITE_OK ){
      break;
    }
    alreadyExists = (res==0);
    pC->deferredMoveto = 0;
    pC->cacheStatus = CACHE_STALE;

    len = nKey-szRowid;

    /* Search for an entry in P1 where all but the last four bytes match K.
    ** If there is no such entry, jump immediately to P2.
    */
    assert( pCx->deferredMoveto==0 );
    pCx->cacheStatus = CACHE_STALE;
    rc = sqlite3BtreeMoveto(pCrsr, zKey, len, 0, &res);
    if( rc!=SQLITE_OK ){
      goto abort_due_to_error;
    }
    if( res<0 ){
      rc = sqlite3BtreeNext(pCrsr, &res);
      if( res ){
        pc = pOp->p2 - 1;

  assert( p->apCsr[i]!=0 );
  if( (pCrsr = (pC = p->apCsr[i])->pCursor)!=0 ){
    int res;
    u64 iKey;
    assert( pIn3->flags & MEM_Int );
    assert( p->apCsr[i]->isTable );
    iKey = intToKey(pIn3->u.i);
    rc = sqlite3BtreeMoveto(pCrsr, 0, iKey, 0,&res);
    pC->lastRowid = pIn3->u.i;
    pC->rowidIsValid = res==0;
    pC->nullRow = 0;
    pC->cacheStatus = CACHE_STALE;
    /* res might be uninitialized if rc!=SQLITE_OK.  But if rc!=SQLITE_OK
    ** processing is about to abort so we really do not care whether or not
    ** the following jump is taken.  (In other words, do not stress over

          v++;
        }else{
          sqlite3_randomness(sizeof(v), &v);
          if( cnt<5 ) v &= 0xffffff;
        }
        if( v==0 ) continue;
        x = intToKey(v);
        rx = sqlite3BtreeMoveto(pC->pCursor, 0, (u64)x, 0, &res);
        cnt++;
      }while( cnt<100 && rx==SQLITE_OK && res==0 );
      db->priorNewRowid = v;
      if( rx==SQLITE_OK && res==0 ){
        rc = SQLITE_FULL;
        goto abort_due_to_error;
      }

      assert( pC->deferredMoveto==0 );
      pC->cacheStatus = CACHE_STALE;
    }
  }
  break;
}

/* Opcode: IdxDelete P1 P2 * * *
**
** The content of register P2 is an index key built using the 
** MakeIdxRec opcode. This opcode removes that entry from the 
** index opened by cursor P1.
*/
case OP_IdxDelete: {        /* in2 */
  int i = pOp->p1;
  Cursor *pC;
  BtCursor *pCrsr;
  assert( pIn2->flags & MEM_Blob );

  assert( i>=0 && i<p->nCursor );
  assert( p->apCsr[i]!=0 );
  if( (pCrsr = (pC = p->apCsr[i])->pCursor)!=0 ){
    int res;






    rc = sqlite3BtreeMoveto(pCrsr, pIn2->z, pIn2->n, 0, &res);
    if( rc==SQLITE_OK && res==0 ){
      rc = sqlite3BtreeDelete(pCrsr);
    }
    assert( pC->deferredMoveto==0 );
    pC->cacheStatus = CACHE_STALE;
  }
  break;

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.127 2008/03/25 00:22:21 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines
** in the source file sqliteVdbe.c are allowed to see the insides
** of this structure.
*/
typedef struct Vdbe Vdbe;

/*
** The names of the following types declared in vdbeInt.h are required
** for the VdbeOp definition.
*/
typedef struct VdbeFunc VdbeFunc;
typedef struct Mem Mem;
typedef struct VdbeParsedRecord VdbeParsedRecord;

/*
** A single instruction of the virtual machine has an opcode
** and as many as three operands.  The instruction is recorded
** as an instance of the following structure:
*/
struct VdbeOp {

void sqlite3VdbeSetNumCols(Vdbe*,int);
int sqlite3VdbeSetColName(Vdbe*, int, int, const char *, int);
void sqlite3VdbeCountChanges(Vdbe*);
sqlite3 *sqlite3VdbeDb(Vdbe*);
void sqlite3VdbeSetSql(Vdbe*, const char *z, int n);
void sqlite3VdbeSwap(Vdbe*,Vdbe*);

VdbeParsedRecord *sqlite3VdbeRecordParse(KeyInfo*,int,const void*,void*,int);
void sqlite3VdbeRecordUnparse(VdbeParsedRecord*);
int sqlite3VdbeRecordCompareParsed(int,const void*,VdbeParsedRecord*);


#ifndef NDEBUG
  void sqlite3VdbeComment(Vdbe*, const char*, ...);
# define VdbeComment(X)  sqlite3VdbeComment X
#else
# define VdbeComment(X)
#endif

#endif

#endif
  int openedStatement;  /* True if this VM has opened a statement journal */
#ifdef SQLITE_SSE
  int fetchId;          /* Statement number used by sqlite3_fetch_statement */
  int lru;              /* Counter used for LRU cache replacement */
#endif
};























/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */
#define VDBE_MAGIC_RUN      0xbdf20da3    /* VDBE is ready to execute */
#define VDBE_MAGIC_HALT     0x519c2973    /* VDBE has completed execution */

int sqlite3VdbeCursorMoveto(Cursor *p){
  if( p->deferredMoveto ){
    int res, rc;
#ifdef SQLITE_TEST
    extern int sqlite3_search_count;
#endif
    assert( p->isTable );
    rc = sqlite3BtreeMoveto(p->pCursor, 0, p->movetoTarget, 0, &res);
    if( rc ) return rc;
    *p->pIncrKey = 0;
    p->lastRowid = keyToInt(p->movetoTarget);
    p->rowidIsValid = res==0;
    if( res<0 ){
      rc = sqlite3BtreeNext(p->pCursor, &res);
      if( rc ) return rc;

**     x = sqlite3GetVarint32( A, &B );
**
**     x = GetVarint( A, B );
**
*/
#define GetVarint(A,B)  ((B = *(A))<=0x7f ? 1 : sqlite3GetVarint32(A, &B))

#if 0
/*
** This function compares the two table rows or index records specified by 
** {nKey1, pKey1} and {nKey2, pKey2}, returning a negative, zero
** or positive integer if {nKey1, pKey1} is less than, equal to or 
** greater than {nKey2, pKey2}.  Both Key1 and Key2 must be byte strings
** composed by the OP_MakeRecord opcode of the VDBE.
**
** Key1 and Key2 do not have to contain the same number of fields.
** But if the lengths differ, Key2 must be the shorter of the two.
*/
int sqlite3VdbeRecordCompare(
  void *userData,
  int nKey1, const void *pKey1, 
  int nKey2, const void *pKey2
){
  KeyInfo *pKeyInfo = (KeyInfo*)userData;
  u32 d1, d2;          /* Offset into aKey[] of next data element */
  u32 idx1, idx2;      /* Offset into aKey[] of next header element */
  u32 szHdr1, szHdr2;  /* Number of bytes in header */
  int i = 0;
  int nField;
  int rc = 0;
  const unsigned char *aKey1 = (const unsigned char *)pKey1;
  const unsigned char *aKey2 = (const unsigned char *)pKey2;

  Mem mem1;
  Mem mem2;
  mem1.enc = pKeyInfo->enc;
  mem1.db = pKeyInfo->db;
  mem1.flags = 0;
  mem2.enc = pKeyInfo->enc;
  mem2.db = pKeyInfo->db;
  mem2.flags = 0;
  
  idx1 = GetVarint(aKey1, szHdr1);
  d1 = szHdr1;
  idx2 = GetVarint(aKey2, szHdr2);
  d2 = szHdr2;
  nField = pKeyInfo->nField;
  while( idx1<szHdr1 && idx2<szHdr2 ){
    u32 serial_type1;
    u32 serial_type2;

    /* Read the serial types for the next element in each key. */
    idx1 += GetVarint( aKey1+idx1, serial_type1 );
    if( d1>=nKey1 && sqlite3VdbeSerialTypeLen(serial_type1)>0 ) break;
    idx2 += GetVarint( aKey2+idx2, serial_type2 );
    if( d2>=nKey2 && sqlite3VdbeSerialTypeLen(serial_type2)>0 ) break;

    /* Extract the values to be compared.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);
    d2 += sqlite3VdbeSerialGet(&aKey2[d2], serial_type2, &mem2);

    /* Do the comparison
    */
    rc = sqlite3MemCompare(&mem1, &mem2, i<nField ? pKeyInfo->aColl[i] : 0);
    if( mem1.flags&MEM_Dyn ) sqlite3VdbeMemRelease(&mem1);
    if( mem2.flags&MEM_Dyn ) sqlite3VdbeMemRelease(&mem2);
    if( rc!=0 ){
      break;
    }
    i++;
  }

  /* One of the keys ran out of fields, but all the fields up to that point
  ** were equal. If the incrKey flag is true, then the second key is
  ** treated as larger.
  */
  if( rc==0 ){
    if( pKeyInfo->incrKey ){
      rc = -1;
    }else if( !pKeyInfo->prefixIsEqual ){
      if( d1<nKey1 ){
        rc = 1;
      }else if( d2<nKey2 ){
        rc = -1;  /* Only occurs on a corrupt database file */
      }
    }
  }else if( pKeyInfo->aSortOrder && i<pKeyInfo->nField
               && pKeyInfo->aSortOrder[i] ){
    rc = -rc;
  }

  return rc;
}
#endif

/*
** An instance of the following structure holds information about a
** single index record that has already been parsed out into individual
** values.
**
** A record is an object that contains one or more fields of data.
** Records are used to store the content of a table row and to store
** the key of an index.  A blob encoding of a record is created by
** the OP_MakeRecord opcode of the VDBE and is disassemblied by the
** OP_Column opcode.
**
** This structure holds a record that has already been disassembled
** into its constitutent fields.
*/
struct VdbeParsedRecord {
  KeyInfo *pKeyInfo;  /* Collation and sort-order information */
  u16 nField;         /* Number of entries in apMem[] */
  u8 needFree;        /* True if memory obtained from sqlite3_malloc() */
  u8 needDestroy;     /* True if apMem[]s should be destroyed on close */
  Mem *apMem[1];      /* Values */
};

/*
** Given the nKey-byte encoding of a record in pKey[], parse the
** record into a VdbeParsedRecord structure.  Return a pointer to
** that structure.
**
** The calling function might provide szSpace bytes of memory
** space at pSpace.  This space can be used to hold the returned
** VDbeParsedRecord structure if it is large enough.  If it is
** not big enough, space is obtained from sqlite3_malloc().
**
** The returned structure should be closed by a call to
** sqlite3VdbeRecordUnparse().
*/ 
VdbeParsedRecord *sqlite3VdbeRecordParse(
  KeyInfo *pKeyInfo,     /* Information about the record format */
  int nKey,              /* Size of the binary record */
  const void *pKey,      /* The binary record */
  void *pSpace,          /* Space available to hold resulting object */
  int szSpace            /* Size of pSpace[] in bytes */
){
  const unsigned char *aKey = (const unsigned char *)pKey;
  VdbeParsedRecord *p;
  int nByte;
  int i, idx, d;
  u32 szHdr;
  Mem *pMem;
  
  nByte = sizeof(*p) + sizeof(Mem*)*pKeyInfo->nField
                     + sizeof(Mem)*(pKeyInfo->nField+1);
  if( nByte>szSpace ){
    p = sqlite3DbMallocRaw(pKeyInfo->db, nByte);
    if( p==0 ) return 0;
    p->needFree = 1;
  }else{
    p = pSpace;
    p->needFree = 0;
  }
  p->pKeyInfo = pKeyInfo;
  p->nField = pKeyInfo->nField + 1;
  p->needDestroy = 1;
  pMem = (Mem*)&p->apMem[pKeyInfo->nField+1];
  idx = GetVarint(aKey, szHdr);
  d = szHdr;
  i = 0;
  while( idx<szHdr && i<p->nField ){
    u32 serial_type;

    idx += GetVarint( aKey+idx, serial_type);
    if( d>=nKey && sqlite3VdbeSerialTypeLen(serial_type)>0 ) break;
    pMem->enc = pKeyInfo->enc;
    pMem->db = pKeyInfo->db;
    pMem->flags = 0;
    d += sqlite3VdbeSerialGet(&aKey[d], serial_type, pMem);
    p->apMem[i++] = pMem++;

  }
  p->nField = i;
  return (void*)p;
}

/*
** This routine destroys a VdbeParsedRecord object
*/
void sqlite3VdbeRecordUnparse(VdbeParsedRecord *p){
  if( p ){
    if( p->needDestroy ){
      int i;

      for(i=0; i<p->nField; i++){
        if( p->apMem[i]->flags & MEM_Dyn ){
          sqlite3VdbeMemRelease(p->apMem[i]);
        }
      }
    }
    if( p->needFree ){
      sqlite3_free(p);
    }
  }

** Historical note: In earlier versions of this routine both Key1
** and Key2 were blobs obtained from OP_MakeRecord.  But we found
** that in typical use the same Key2 would be submitted multiple times
** in a row.  So an optimization was added to parse the Key2 key
** separately and submit the parsed version.  In this way, we avoid
** parsing the same Key2 multiple times in a row.
*/
int sqlite3VdbeRecordCompareParsed(
  int nKey1, const void *pKey1, 
  VdbeParsedRecord *pPKey2
){
  u32 d1;            /* Offset into aKey[] of next data element */
  u32 idx1;          /* Offset into aKey[] of next header element */
  u32 szHdr1;        /* Number of bytes in header */
  int i = 0;
  int nField;
  int rc = 0;

    /* Extract the values to be compared.
    */
    d1 += sqlite3VdbeSerialGet(&aKey1[d1], serial_type1, &mem1);

    /* Do the comparison
    */
    rc = sqlite3MemCompare(&mem1, pPKey2->apMem[i],
                           i<nField ? pKeyInfo->aColl[i] : 0);
    if( mem1.flags&MEM_Dyn ) sqlite3VdbeMemRelease(&mem1);
    if( rc!=0 ){
      break;
    }
    i++;
  }

  int *res                    /* Write the comparison result here */
){
  i64 nCellKey = 0;
  int rc;
  BtCursor *pCur = pC->pCursor;
  int lenRowid;
  Mem m;
  VdbeParsedRecord *pRec;
  char zSpace[200];

  sqlite3BtreeKeySize(pCur, &nCellKey);
  if( nCellKey<=0 ){
    *res = 0;
    return SQLITE_OK;
  }
  m.db = 0;
  m.flags = 0;
  rc = sqlite3VdbeMemFromBtree(pC->pCursor, 0, nCellKey, 1, &m);
  if( rc ){
    return rc;
  }
  lenRowid = sqlite3VdbeIdxRowidLen((u8*)m.z);
  pRec = sqlite3VdbeRecordParse(pC->pKeyInfo, nKey, pKey,
                                zSpace, sizeof(zSpace));
  if( pRec==0 ){
    return SQLITE_NOMEM;
  }
  *res = sqlite3VdbeRecordCompareParsed(m.n-lenRowid, m.z, pRec);
  sqlite3VdbeRecordUnparse(pRec);
  sqlite3VdbeMemRelease(&m);
  return SQLITE_OK;
}

/*
** This routine sets the value to be returned by subsequent calls to
** sqlite3_changes() on the database handle 'db'.