SQLite

/*
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.76 2003/01/02 14:43:56 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

** the database is empty) then *pSize is set to 0.
*/
int sqliteBtreeKeySize(BtCursor *pCur, int *pSize){
  Cell *pCell;
  MemPage *pPage;

  pPage = pCur->pPage;
  assert( pPage!=0 );
  if( pCur->idx >= pPage->nCell ){
    *pSize = 0;
  }else{
    pCell = pPage->apCell[pCur->idx];
    *pSize = NKEY(pCur->pBt, pCell->h);
  }
  return SQLITE_OK;
}

  return SQLITE_OK;
}

/*
** Read part of the key associated with cursor pCur.  A maximum
** of "amt" bytes will be transfered into zBuf[].  The transfer
** begins at "offset".  The number of bytes actually read is
** returned. 
**
** Change:  It used to be that the amount returned will be smaller
** than the amount requested if there are not enough bytes in the key
** to satisfy the request.  But now, it must be the case that there
** is enough data available to satisfy the request.  If not, an exception
** is raised.  The change was made in an effort to boost performance
** by eliminating unneeded tests.
*/
int sqliteBtreeKey(BtCursor *pCur, int offset, int amt, char *zBuf){

  MemPage *pPage;

  assert( amt>=0 );
  assert( offset>=0 );
  assert( pCur->pPage!=0 );
  pPage = pCur->pPage;

  if( pCur->idx >= pPage->nCell ){
    return 0;
  }
  assert( amt+offset <= NKEY(pCur->pBt, pPage->apCell[pCur->idx]->h) );






  getPayload(pCur, offset, amt, zBuf);
  return amt;
}

/*
** Set *pSize to the number of bytes of data in the entry the
** cursor currently points to.  Always return SQLITE_OK.
** Failure is not possible.  If the cursor is not currently
** pointing to an entry (which can happen, for example, if
** the database is empty) then *pSize is set to 0.
*/
int sqliteBtreeDataSize(BtCursor *pCur, int *pSize){
  Cell *pCell;
  MemPage *pPage;

  pPage = pCur->pPage;
  assert( pPage!=0 );
  if( pCur->idx >= pPage->nCell ){
    *pSize = 0;
  }else{
    pCell = pPage->apCell[pCur->idx];
    *pSize = NDATA(pCur->pBt, pCell->h);
  }
  return SQLITE_OK;
}

/*
** Read part of the data associated with cursor pCur.  A maximum
** of "amt" bytes will be transfered into zBuf[].  The transfer
** begins at "offset".  The number of bytes actually read is
** returned.  The amount returned will be smaller than the
** amount requested if there are not enough bytes in the data
** to satisfy the request.
*/
int sqliteBtreeData(BtCursor *pCur, int offset, int amt, char *zBuf){
  Cell *pCell;
  MemPage *pPage;


  assert( amt>=0 );
  assert( offset>=0 );
  assert( pCur->pPage!=0 );
  pPage = pCur->pPage;
  if( pCur->idx >= pPage->nCell ){
    return 0;
  }
  pCell = pPage->apCell[pCur->idx];
  assert( amt+offset <= NDATA(pCur->pBt, pCell->h) );






  getPayload(pCur, offset + NKEY(pCur->pBt, pCell->h), amt, zBuf);
  return amt;
}

/*
** Compare an external key against the key on the entry that pCur points to.
**

    if( rc ) return rc;
  }
  /* NOT REACHED */
}

/*
** Advance the cursor to the next entry in the database.  If
** successful then set *pRes=0.  If the cursor
** was already pointing to the last entry in the database before
** this routine was called, then set *pRes=1.
*/
int sqliteBtreeNext(BtCursor *pCur, int *pRes){
  int rc;
  assert( pRes!=0 );
  /* assert( pCur->pPage!=0 ); */
  if( pCur->pPage==0 ){
    *pRes = 1;
    return SQLITE_ABORT;
  }
  assert( pCur->pPage->isInit );
  assert( pCur->eSkip!=SKIP_INVALID );
  if( pCur->pPage->nCell==0 ){
    *pRes = 1;
    return SQLITE_OK;
  }
  assert( pCur->idx<pCur->pPage->nCell );
  if( pCur->eSkip==SKIP_NEXT ){
    pCur->eSkip = SKIP_NONE;
    *pRes = 0;
    return SQLITE_OK;
  }
  pCur->eSkip = SKIP_NONE;
  pCur->idx++;
  if( pCur->idx>=pCur->pPage->nCell ){
    if( pCur->pPage->u.hdr.rightChild ){
      rc = moveToChild(pCur, SWAB32(pCur->pBt, pCur->pPage->u.hdr.rightChild));
      if( rc ) return rc;
      rc = moveToLeftmost(pCur);

      *pRes = 0;
      return rc;
    }
    do{
      if( pCur->pPage->pParent==0 ){
        *pRes = 1;
        return SQLITE_OK;
      }
      rc = moveToParent(pCur);

    }while( rc==SQLITE_OK && pCur->idx>=pCur->pPage->nCell );
    *pRes = 0;
    return rc;
  }
  rc = moveToLeftmost(pCur);

  *pRes = 0;
  return rc;
}

/*
** Step the cursor to the back to the previous entry in the database.  If
** successful and pRes!=NULL then set *pRes=0.  If the cursor
** was already pointing to the first entry in the database before
** this routine was called, then set *pRes=1 if pRes!=NULL.

    ** We have to fill the hole by moving in a cell from a leaf.  The
    ** next Cell after the one to be deleted is guaranteed to exist and
    ** to be a leaf so we can use it.
    */
    BtCursor leafCur;
    Cell *pNext;
    int szNext;
    int notUsed;
    getTempCursor(pCur, &leafCur);
    rc = sqliteBtreeNext(&leafCur, &notUsed);
    if( rc!=SQLITE_OK ){
      return SQLITE_CORRUPT;
    }
    rc = sqlitepager_write(leafCur.pPage);
    if( rc ) return rc;
    dropCell(pBt, pPage, pCur->idx, cellSize(pBt, pCell));
    pNext = leafCur.pPage->apCell[leafCur.idx];

      int nPage = (sz - MX_LOCAL_PAYLOAD + OVERFLOW_SIZE - 1)/OVERFLOW_SIZE;
      checkList(pCheck, 0, SWAB32(pBt, pCell->ovfl), nPage, zContext);
    }

    /* Check that keys are in the right order
    */
    cur.idx = i;
    zKey2 = sqliteMallocRaw( nKey2+1 );
    getPayload(&cur, 0, nKey2, zKey2);
    if( zKey1 && keyCompare(zKey1, nKey1, zKey2, nKey2)>=0 ){
      checkAppendMsg(pCheck, zContext, "Key is out of order");
    }

    /* Check sanity of left child page.
    */

  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = sqlitepager_pagecount(sCheck.pPager);
  if( sCheck.nPage==0 ){
    unlockBtreeIfUnused(pBt);
    return 0;
  }
  sCheck.anRef = sqliteMallocRaw( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
  sCheck.anRef[1] = 1;
  for(i=2; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
  sCheck.zErrMsg = 0;

  /* Check the integrity of the freelist
  */
  checkList(&sCheck, 1, SWAB32(pBt, pBt->page1->freeList),

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.118 2003/01/02 14:43:56 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called when a new SQL statement is beginning to
** be parsed.  Check to see if the schema for the database needs

    zEnd = ")";
  }else{
    zSep = "\n  ";
    zSep2 = ",\n  ";
    zEnd = "\n)";
  }
  n += 35 + 6*p->nCol;
  zStmt = sqliteMallocRaw( n );
  if( zStmt==0 ) return 0;
  strcpy(zStmt, p->isTemp ? "CREATE TEMP TABLE " : "CREATE TABLE ");
  k = strlen(zStmt);
  identPut(zStmt, &k, p->zName);
  zStmt[k++] = '(';
  for(i=0; i<p->nCol; i++){
    strcpy(&zStmt[k], zSep);

void sqliteAddIdxKeyType(Vdbe *v, Index *pIdx){
  char *zType;
  Table *pTab;
  int i, n;
  assert( pIdx!=0 && pIdx->pTable!=0 );
  pTab = pIdx->pTable;
  n = pIdx->nColumn;
  zType = sqliteMallocRaw( n+1 );
  if( zType==0 ) return;
  for(i=0; i<n; i++){
    int iCol = pIdx->aiColumn[i];
    assert( iCol>=0 && iCol<pTab->nCol );
    if( (pTab->aCol[iCol].sortOrder & SQLITE_SO_TYPEMASK)==SQLITE_SO_TEXT ){
      zType[i] = 't';
    }else{

**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This is the implementation of generic hash-tables
** used in SQLite.
**
** $Id: hash.c,v 1.9 2003/01/02 14:43:57 drh Exp $
*/
#include "sqliteInt.h"
#include <assert.h>

/* Turn bulk memory into a hash table object by initializing the
** fields of the Hash structure.
**

    }
    return old_data;
  }
  if( data==0 ) return 0;
  new_elem = (HashElem*)sqliteMalloc( sizeof(HashElem) );
  if( new_elem==0 ) return data;
  if( pH->copyKey && pKey!=0 ){
    new_elem->pKey = sqliteMallocRaw( nKey );
    if( new_elem->pKey==0 ){
      sqliteFree(new_elem);
      return data;
    }
    memcpy((void*)new_elem->pKey, pKey, nKey);
  }else{
    new_elem->pKey = (void*)pKey;

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.63 2003/01/02 14:43:57 drh Exp $
*/
#include "os.h"         /* Must be first to enable large file support */
#include "sqliteInt.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

  }
  if( pPg==0 ){
    /* The requested page is not in the page cache. */
    int h;
    pPager->nMiss++;
    if( pPager->nPage<pPager->mxPage || pPager->pFirst==0 ){
      /* Create a new page */
      pPg = sqliteMallocRaw( sizeof(*pPg) + SQLITE_PAGE_SIZE + pPager->nExtra );
      if( pPg==0 ){
        *ppPage = 0;
        pager_unwritelock(pPager);
        pPager->errMask |= PAGER_ERR_MEM;
        return SQLITE_NOMEM;
      }
      memset(pPg, 0, sizeof(*pPg));
      pPg->pPager = pPager;
      pPg->pNextAll = pPager->pAll;
      if( pPager->pAll ){
        pPager->pAll->pPrevAll = pPg;
      }
      pPg->pPrevAll = 0;
      pPager->pAll = pPg;

/*
** 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 1.151 2003/01/02 14:43:57 drh Exp $
*/
#include "config.h"
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"

**      -DMEMORY_DEBUG=2
**
** and a line of text will be written to standard error for
** each malloc() and free().  This output can be analyzed
** by an AWK script to determine if there are any leaks.
*/
#ifdef MEMORY_DEBUG
# define sqliteMalloc(X)    sqliteMalloc_(X,1,__FILE__,__LINE__)
# define sqliteMallocRaw(X) sqliteMalloc_(X,0,__FILE__,__LINE__)
# define sqliteFree(X)      sqliteFree_(X,__FILE__,__LINE__)
# define sqliteRealloc(X,Y) sqliteRealloc_(X,Y,__FILE__,__LINE__)
# define sqliteStrDup(X)    sqliteStrDup_(X,__FILE__,__LINE__)
# define sqliteStrNDup(X,Y) sqliteStrNDup_(X,Y,__FILE__,__LINE__)
  void sqliteStrRealloc(char**);
#else
# define sqliteStrRealloc(X)

int sqliteStrICmp(const char *, const char *);
int sqliteStrNICmp(const char *, const char *, int);
int sqliteHashNoCase(const char *, int);
int sqliteCompare(const char *, const char *);
int sqliteSortCompare(const char *, const char *);
void sqliteRealToSortable(double r, char *);
#ifdef MEMORY_DEBUG
  void *sqliteMalloc_(int,int,char*,int);
  void sqliteFree_(void*,char*,int);
  void *sqliteRealloc_(void*,int,char*,int);
  char *sqliteStrDup_(const char*,char*,int);
  char *sqliteStrNDup_(const char*, int,char*,int);
#else
  void *sqliteMalloc(int);
  void *sqliteMallocRaw(int);
  void sqliteFree(void*);
  void *sqliteRealloc(void*,int);
  char *sqliteStrDup(const char*);
  char *sqliteStrNDup(const char*, int);
#endif
void sqliteSetString(char **, const char *, ...);
void sqliteSetNString(char **, ...);

**
*************************************************************************
** Utility functions used throughout sqlite.
**
** This file contains functions for allocating memory, comparing
** strings, and stuff like that.
**
** $Id: util.c,v 1.54 2003/01/02 14:43:57 drh Exp $
*/
#include "sqliteInt.h"
#include <stdarg.h>
#include <ctype.h>

/*
** If malloc() ever fails, this global variable gets set to 1.

#endif


/*
** Allocate new memory and set it to zero.  Return NULL if
** no memory is available.
*/
void *sqliteMalloc_(int n, int bZero, char *zFile, int line){
  void *p;
  int *pi;
  int k;
  if( sqlite_iMallocFail>=0 ){
    sqlite_iMallocFail--;
    if( sqlite_iMallocFail==0 ){
      sqlite_malloc_failed++;

    return 0;
  }
  sqlite_nMalloc++;
  pi[0] = 0xdead1122;
  pi[1] = n;
  pi[k+2] = 0xdead3344;
  p = &pi[2];
  memset(p, bZero==0, n);
#if MEMORY_DEBUG>1
  fprintf(stderr,"%06d malloc %d bytes at 0x%x from %s:%d\n",
      ++memcnt, n, (int)p, zFile,line);
#endif
  return p;
}

** works just like sqliteMalloc().  If n==0, then this routine
** works just like sqliteFree().
*/
void *sqliteRealloc_(void *oldP, int n, char *zFile, int line){
  int *oldPi, *pi, k, oldN, oldK;
  void *p;
  if( oldP==0 ){
    return sqliteMalloc_(n,1,zFile,line);
  }
  if( n==0 ){
    sqliteFree_(oldP,zFile,line);
    return 0;
  }
  oldPi = oldP;
  oldPi -= 2;

  pi[1] = n;
  pi[k+2] = 0xdead3344;
  p = &pi[2];
  memcpy(p, oldP, n>oldN ? oldN : n);
  if( n>oldN ){
    memset(&((char*)p)[oldN], 0, n-oldN);
  }
  memset(oldPi, 0xab, (oldK+3)*sizeof(int));
  free(oldPi);
#if MEMORY_DEBUG>1
  fprintf(stderr,"%06d realloc %d to %d bytes at 0x%x to 0x%x at %s:%d\n",
    ++memcnt, oldN, n, (int)oldP, (int)p, zFile, line);
#endif
  return p;
}

/*
** Make a copy of a string in memory obtained from sqliteMalloc()
*/
char *sqliteStrDup_(const char *z, char *zFile, int line){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMalloc_(strlen(z)+1, 0, zFile, line);
  if( zNew ) strcpy(zNew, z);
  return zNew;
}
char *sqliteStrNDup_(const char *z, int n, char *zFile, int line){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMalloc_(n+1, 0, zFile, line);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}
#endif /* MEMORY_DEBUG */

/*
** The following versions of malloc() and free() are for use in a
** normal build.
*/
#if !defined(MEMORY_DEBUG)

/*
** Allocate new memory and set it to zero.  Return NULL if
** no memory is available.  See also sqliteMallocRaw().
*/
void *sqliteMalloc(int n){
  void *p;
  if( n==0 ) return 0;
  p = malloc(n);
  if( p==0 ){
    sqlite_malloc_failed++;
    return 0;
  }
  memset(p, 0, n);
  return p;
}

/*
** Allocate new memory but do not set it to zero.  Return NULL if
** no memory is available.  See also sqliteMalloc().
*/
void *sqliteMallocRaw(int n){
  void *p;
  if( n==0 ) return 0;
  p = malloc(n);
  if( p==0 ){
    sqlite_malloc_failed++;
    return 0;
  }
  return p;
}

/*
** Free memory previously obtained from sqliteMalloc()
*/
void sqliteFree(void *p){
  if( p ){
    free(p);

/*
** Make a copy of a string in memory obtained from sqliteMalloc()
*/
char *sqliteStrDup(const char *z){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMallocRaw(strlen(z)+1);
  if( zNew ) strcpy(zNew, z);
  return zNew;
}
char *sqliteStrNDup(const char *z, int n){
  char *zNew;
  if( z==0 ) return 0;
  zNew = sqliteMallocRaw(n+1);
  if( zNew ){
    memcpy(zNew, z, n);
    zNew[n] = 0;
  }
  return zNew;
}
#endif /* !defined(MEMORY_DEBUG) */

  nByte = strlen(zFirst) + 1;
  va_start(ap, zFirst);
  while( (z = va_arg(ap, const char*))!=0 ){
    nByte += strlen(z);
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte );
  if( zResult==0 ){
    return;
  }
  strcpy(zResult, zFirst);
  zResult += strlen(zResult);
  va_start(ap, zFirst);
  while( (z = va_arg(ap, const char*))!=0 ){

  while( (z = va_arg(ap, const char*))!=0 ){
    n = va_arg(ap, int);
    if( n<=0 ) n = strlen(z);
    nByte += n;
  }
  va_end(ap);
  sqliteFree(*pz);
  *pz = zResult = sqliteMallocRaw( nByte + 1 );
  if( zResult==0 ) return;
  va_start(ap, pz);
  while( (z = va_arg(ap, const char*))!=0 ){
    n = va_arg(ap, int);
    if( n<=0 ) n = strlen(z);
    strncpy(zResult, z, n);
    zResult += n;

**
** 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 1.189 2003/01/02 14:43:57 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The makefile scans this source file and creates the following
** array of string constants which are the names of all VDBE opcodes.

    if( n<0 ) n = strlen(zResult);
    if( n<NBFS-1 ){
      memcpy(p->s.z, zResult, n);
      p->s.z[n] = 0;
      p->s.flags = STK_Str;
      p->z = p->s.z;
    }else{
      p->z = sqliteMallocRaw( n+1 );
      if( p->z ){
        memcpy(p->z, zResult, n);
        p->z[n] = 0;
      }
      p->s.flags = STK_Str | STK_Dyn;
    }
    p->s.n = n+1;

#define Deephemeralize(P,I) \
   if( ((P)->aStack[I].flags&STK_Ephem)!=0 && hardDeephem(P,I) ){ goto no_mem;}
static int hardDeephem(Vdbe *p, int i){
  Stack *pStack = &p->aStack[i];
  char **pzStack = &p->zStack[i];
  char *z;
  assert( (pStack->flags & STK_Ephem)!=0 );
  z = sqliteMallocRaw( pStack->n );
  if( z==0 ) return 1;
  memcpy(z, *pzStack, pStack->n);
  *pzStack = z;
  return 0;
}

/*

      aStack[j].flags &= ~STK_Dyn;
      if( !isStatic ) aStack[j].flags |= STK_Ephem;
    }else if( aStack[i].n<=NBFS ){
      memcpy(aStack[j].z, zStack[i], aStack[j].n);
      zStack[j] = aStack[j].z;
      aStack[j].flags &= ~(STK_Static|STK_Dyn|STK_Ephem);
    }else{
      zStack[j] = sqliteMallocRaw( aStack[j].n );
      if( zStack[j]==0 ) goto no_mem;
      memcpy(zStack[j], zStack[i], aStack[j].n);
      aStack[j].flags &= ~(STK_Static|STK_Ephem);
      aStack[j].flags |= STK_Dyn;
    }
  }
  break;

    if( pOp->p2==0 ) PopStack(p, nField);
    VERIFY( NeedStack(p, p->tos+1); )
    p->tos++;
    aStack[p->tos].flags = STK_Null;
    zStack[p->tos] = 0;
    break;
  }
  zNew = sqliteMallocRaw( nByte );
  if( zNew==0 ) goto no_mem;
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      memcpy(&zNew[j], zStack[i], aStack[i].n-1);
      j += aStack[i].n-1;
    }

    idxWidth = 3;
  }
  nByte += idxWidth*(nField + 1);
  if( nByte>MAX_BYTES_PER_ROW ){
    rc = SQLITE_TOOBIG;
    goto abort_due_to_error;
  }
  zNewRecord = sqliteMallocRaw( nByte );
  if( zNewRecord==0 ) goto no_mem;
  j = 0;
  addr = idxWidth*(nField+1) + addUnique*sizeof(uniqueCnt);
  for(i=p->tos-nField+1; i<=p->tos; i++){
    zNewRecord[j++] = addr & 0xff;
    if( idxWidth>1 ){
      zNewRecord[j++] = (addr>>8)&0xff;

    }
  }
  if( nByte+sizeof(u32)>MAX_BYTES_PER_ROW ){
    rc = SQLITE_TOOBIG;
    goto abort_due_to_error;
  }
  if( addRowid ) nByte += sizeof(u32);
  zNewKey = sqliteMallocRaw( nByte );
  if( zNewKey==0 ) goto no_mem;
  j = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( aStack[i].flags & STK_Null ){
      zNewKey[j++] = 'a';
      zNewKey[j++] = 0;
    }else{

    zStack[tos] = &zRec[offset];
  }else{
    if( amt<=NBFS ){
      aStack[tos].flags = STK_Str;
      zStack[tos] = aStack[tos].z;
      aStack[tos].n = amt;
    }else{
      char *z = sqliteMallocRaw( amt );
      if( z==0 ) goto no_mem;
      aStack[tos].flags = STK_Str | STK_Dyn;
      zStack[tos] = z;
      aStack[tos].n = amt;
    }
    if( pC->keyAsData ){
      sqliteBtreeKey(pCrsr, offset, amt, zStack[tos]);

    sqliteBtreeKeySize(pCrsr, &amt);
    if( amt<=0 ){
      rc = SQLITE_CORRUPT;
      goto abort_due_to_error;
    }
    if( amt>NBFS ){
      z = sqliteMallocRaw( amt );
      aStack[tos].flags = STK_Str | STK_Dyn;
    }else{
      z = aStack[tos].z;
      aStack[tos].flags = STK_Str;
    }
    sqliteBtreeKey(pCrsr, 0, amt, z);
    zStack[tos] = z;

** Back up cursor P1 so that it points to the previous key/data pair in its
** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
*/
case OP_Prev:
case OP_Next: {

  Cursor *pC;
  BtCursor *pCrsr;

  if( VERIFY( pOp->p1>=0 && pOp->p1<p->nCursor && ) 
      (pCrsr = (pC = &p->aCsr[pOp->p1])->pCursor)!=0 ){
    int res;
    if( pC->nullRow ){
      res = 1;
    }else{
      rc = pOp->opcode==OP_Next ? sqliteBtreeNext(pCrsr, &res) :
                                  sqliteBtreePrevious(pCrsr, &res);
      pC->nullRow = res;

** into the temporary storage list.
*/
case OP_ListWrite: {
  Keylist *pKeylist;
  VERIFY( if( p->tos<0 ) goto not_enough_stack; )
  pKeylist = p->pList;
  if( pKeylist==0 || pKeylist->nUsed>=pKeylist->nKey ){
    pKeylist = sqliteMallocRaw( sizeof(Keylist)+999*sizeof(pKeylist->aKey[0]) );
    if( pKeylist==0 ) goto no_mem;
    pKeylist->nKey = 1000;
    pKeylist->nRead = 0;
    pKeylist->nUsed = 0;
    pKeylist->pNext = p->pList;
    p->pList = pKeylist;
  }

*/
case OP_SortPut: {
  int tos = p->tos;
  int nos = tos - 1;
  Sorter *pSorter;
  VERIFY( if( tos<1 ) goto not_enough_stack; )
  if( Stringify(p, tos) || Stringify(p, nos) ) goto no_mem;
  pSorter = sqliteMallocRaw( sizeof(Sorter) );
  if( pSorter==0 ) goto no_mem;
  pSorter->pNext = p->pSort;
  p->pSort = pSorter;
  assert( aStack[tos].flags & STK_Dyn );
  pSorter->nKey = aStack[tos].n;
  pSorter->zKey = zStack[tos];
  pSorter->nData = aStack[nos].n;

  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)==0 ){
      if( Stringify(p, i) ) goto no_mem;
      nByte += aStack[i].n;
    }
  }
  nByte += sizeof(char*)*(nField+1);
  azArg = sqliteMallocRaw( nByte );
  if( azArg==0 ) goto no_mem;
  z = (char*)&azArg[nField+1];
  for(j=0, i=p->tos-nField+1; i<=p->tos; i++, j++){
    if( aStack[i].flags & STK_Null ){
      azArg[j] = 0;
    }else{
      azArg[j] = z;

    if( (aStack[i].flags & STK_Null)!=0 ){
      nByte += 2;
    }else{
      if( Stringify(p, i) ) goto no_mem;
      nByte += aStack[i].n+2;
    }
  }
  zNewKey = sqliteMallocRaw( nByte );
  if( zNewKey==0 ) goto no_mem;
  j = 0;
  k = 0;
  for(i=p->tos-nField+1; i<=p->tos; i++){
    if( (aStack[i].flags & STK_Null)!=0 ){
      zNewKey[j++] = 'N';
      zNewKey[j++] = 0;

  }
  pMem->s = aStack[tos];
  flags = pMem->s.flags;
  if( flags & (STK_Static|STK_Dyn|STK_Ephem) ){
    if( (flags & STK_Static)!=0 || (pOp->p2 && (flags & STK_Dyn)!=0) ){
      pMem->z = zStack[tos];
    }else if( flags & STK_Str ){
      pMem->z = sqliteMallocRaw( pMem->s.n );
      if( pMem->z==0 ) goto no_mem;
      memcpy(pMem->z, zStack[tos], pMem->s.n);
      pMem->s.flags |= STK_Dyn;
      pMem->s.flags &= ~(STK_Static|STK_Ephem);
    }
  }else{
    pMem->z = pMem->s.z;