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SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

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Overview
Comment:Work toward multithreading support. Currently crashes quickly on a test. (CVS 4253)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 1315bd8e125602275fb718780f9b2730bd37f6ab
User & Date: drh 2007-08-20 22:48:42
Context
2007-08-20
23:50
The quick test runs again with a handfull of errors after adding the mutex locks to btree, the VFS registration interfaces, and FTS3. (CVS 4254) check-in: 6cf725d2 user: drh tags: trunk
22:48
Work toward multithreading support. Currently crashes quickly on a test. (CVS 4253) check-in: 1315bd8e user: drh tags: trunk
17:53
Oops - a random fts2 test I had abandoned slipped into the fts3 batch. (CVS 4252) check-in: 709f2aa1 user: shess tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to main.mk.

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# Generate the file "last_change" which contains the date of change
# of the most recently modified source code file
#
last_change:	$(SRC)
	cat $(SRC) | grep '$$Id: ' | sort -k 5 | tail -1 \
          | $(NAWK) '{print $$5,$$6}' >last_change

libsqlite3.a:	$(LIBOBJ) $(EXTOBJ)
	$(AR) libsqlite3.a $(LIBOBJ) $(EXTOBJ)
	$(RANLIB) libsqlite3.a

sqlite3$(EXE):	$(TOP)/src/shell.c libsqlite3.a sqlite3.h
	$(TCCX) $(READLINE_FLAGS) -o sqlite3$(EXE)                  \
		$(TOP)/src/shell.c                                  \
		libsqlite3.a $(LIBREADLINE) $(TLIBS) $(THREADLIB)








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# Generate the file "last_change" which contains the date of change
# of the most recently modified source code file
#
last_change:	$(SRC)
	cat $(SRC) | grep '$$Id: ' | sort -k 5 | tail -1 \
          | $(NAWK) '{print $$5,$$6}' >last_change

libsqlite3.a:	$(LIBOBJ)
	$(AR) libsqlite3.a $(LIBOBJ)
	$(RANLIB) libsqlite3.a

sqlite3$(EXE):	$(TOP)/src/shell.c libsqlite3.a sqlite3.h
	$(TCCX) $(READLINE_FLAGS) -o sqlite3$(EXE)                  \
		$(TOP)/src/shell.c                                  \
		libsqlite3.a $(LIBREADLINE) $(TLIBS) $(THREADLIB)

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** 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 1.402 2007/08/20 13:14:29 drh 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"

/*
** The header string that appears at the beginning of every
** SQLite database.
*/
static const char zMagicHeader[] = SQLITE_FILE_HEADER;


/*
** Set this global variable to 1 to enable tracing using the TRACE
** macro.
*/
#if SQLITE_TEST
int sqlite3_btree_trace=0;  /* True to enable tracing */
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** A flag to indicate whether or not shared cache is enabled.  Also,
** a list of BtShared objects that are eligible for participation
** in shared cache.


*/
#ifdef SQLITE_TEST
BtShared *sqlite3SharedCacheList = 0;
int sqlite3SharedCacheEnabled = 0;
#else
static BtShared *sqlite3SharedCacheList = 0;
static int sqlite3SharedCacheEnabled = 0;
#endif

#endif /* SQLITE_OMIT_SHARED_CACHE */

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Enable or disable the shared pager and schema features.
**
** This routine has no effect on existing database connections.
................................................................................
** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
*/
int sqlite3_enable_shared_cache(int enable){
  sqlite3SharedCacheEnabled = enable;
  return SQLITE_OK;
}
#endif


/*
** Forward declaration
*/
static int checkReadLocks(Btree*,Pgno,BtCursor*);


................................................................................
** SQLITE_OK if the lock may be obtained (by calling lockTable()), or
** SQLITE_LOCKED if not.
*/
static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pIter;



  /* This is a no-op if the shared-cache is not enabled */
  if( !p->sharable ){
    return SQLITE_OK;
  }

  /* This (along with lockTable()) is where the ReadUncommitted flag is
  ** dealt with. If the caller is querying for a read-lock and the flag is
................................................................................
** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
** SQLITE_NOMEM may also be returned.
*/
static int lockTable(Btree *p, Pgno iTable, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pLock = 0;
  BtLock *pIter;



  /* This is a no-op if the shared-cache is not enabled */
  if( !p->sharable ){
    return SQLITE_OK;
  }

  assert( SQLITE_OK==queryTableLock(p, iTable, eLock) );
................................................................................
/*
** Release all the table locks (locks obtained via calls to the lockTable()
** procedure) held by Btree handle p.
*/
static void unlockAllTables(Btree *p){
  BtLock **ppIter = &p->pBt->pLock;


  assert( p->sharable || 0==*ppIter );

  while( *ppIter ){
    BtLock *pLock = *ppIter;
    if( pLock->pBtree==p ){
      *ppIter = pLock->pNext;
      sqlite3_free(pLock);
................................................................................

/*
** Invalidate the overflow page-list cache for all cursors opened
** on the shared btree structure pBt.
*/
static void invalidateAllOverflowCache(BtShared *pBt){
  BtCursor *p;

  for(p=pBt->pCursor; p; p=p->pNext){
    invalidateOverflowCache(p);
  }
}
#else
  #define invalidateOverflowCache(x)
  #define invalidateAllOverflowCache(x)
................................................................................
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
*/
static int saveCursorPosition(BtCursor *pCur){
  int rc;

  assert( CURSOR_VALID==pCur->eState );
  assert( 0==pCur->pKey );


  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);

  /* If this is an intKey table, then the above call to BtreeKeySize()
  ** stores the integer key in pCur->nKey. In this case this value is
  ** all that is required. Otherwise, if pCur is not open on an intKey
  ** table, then malloc space for and store the pCur->nKey bytes of key 
................................................................................
/*
** Save the positions of all cursors except pExcept open on the table 
** with root-page iRoot. Usually, this is called just before cursor
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;

  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) && 
        p->eState==CURSOR_VALID ){
      int rc = saveCursorPosition(p);
      if( SQLITE_OK!=rc ){
        return rc;
      }
................................................................................
  return SQLITE_OK;
}

/*
** Clear the current cursor position.
*/
static void clearCursorPosition(BtCursor *pCur){

  sqlite3_free(pCur->pKey);
  pCur->pKey = 0;
  pCur->eState = CURSOR_INVALID;
}

/*
** Restore the cursor to the position it was in (or as close to as possible)
................................................................................
#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
** number for the pointer-map page that contains the entry for the
** input page number.
*/
static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){


  int nPagesPerMapPage = (pBt->usableSize/5)+1;
  int iPtrMap = (pgno-2)/nPagesPerMapPage;
  int ret = (iPtrMap*nPagesPerMapPage) + 2; 
  if( ret==PENDING_BYTE_PAGE(pBt) ){
    ret++;
  }
  return ret;
}

/*
................................................................................
static int ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent){
  DbPage *pDbPage;  /* The pointer map page */
  u8 *pPtrmap;      /* The pointer map data */
  Pgno iPtrmap;     /* The pointer map page number */
  int offset;       /* Offset in pointer map page */
  int rc;


  /* The master-journal page number must never be used as a pointer map page */
  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );

  assert( pBt->autoVacuum );
  if( key==0 ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
*/
static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
  DbPage *pDbPage;   /* The pointer map page */
  int iPtrmap;       /* Pointer map page index */
  u8 *pPtrmap;       /* Pointer map page data */
  int offset;        /* Offset of entry in pointer map */
  int rc;



  iPtrmap = PTRMAP_PAGENO(pBt, key);
  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
  if( rc!=0 ){
    return rc;
  }
  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
................................................................................

/*
** This a more complex version of sqlite3BtreeFindCell() that works for
** pages that do contain overflow cells.  See insert
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;

  for(i=pPage->nOverflow-1; i>=0; i--){
    int k;
    struct _OvflCell *pOvfl;
    pOvfl = &pPage->aOvfl[i];
    k = pOvfl->idx;
    if( k<=iCell ){
      if( k==iCell ){
................................................................................
void sqlite3BtreeParseCellPtr(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  int n;                  /* Number bytes in cell content header */
  u32 nPayload;           /* Number of bytes of cell payload */



  pInfo->pCell = pCell;
  assert( pPage->leaf==0 || pPage->leaf==1 );
  n = pPage->childPtrSize;
  assert( n==4-4*pPage->leaf );
  if( pPage->hasData ){
    n += getVarint32(&pCell[n], &nPayload);
................................................................................
/*
** If the cell with index iCell on page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static int ptrmapPutOvfl(MemPage *pPage, int iCell){
  u8 *pCell;

  pCell = findOverflowCell(pPage, iCell);
  return ptrmapPutOvflPtr(pPage, pCell);
}
#endif


/*
................................................................................
  unsigned char *data;       /* The page data */
  unsigned char *temp;       /* Temp area for cell content */

  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( pPage->pBt!=0 );
  assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
  assert( pPage->nOverflow==0 );

  temp = sqlite3_malloc( pPage->pBt->pageSize );
  if( temp==0 ) return SQLITE_NOMEM;
  data = pPage->aData;
  hdr = pPage->hdrOffset;
  cellOffset = pPage->cellOffset;
  nCell = pPage->nCell;
  assert( nCell==get2byte(&data[hdr+3]) );
................................................................................
  int nCell;
  int cellOffset;
  unsigned char *data;
  
  data = pPage->aData;
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( pPage->pBt );

  if( nByte<4 ) nByte = 4;
  if( pPage->nFree<nByte || pPage->nOverflow>0 ) return 0;
  pPage->nFree -= nByte;
  hdr = pPage->hdrOffset;

  nFrag = data[hdr+7];
  if( nFrag<60 ){
................................................................................
  int addr, pbegin, hdr;
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
  assert( (start + size)<=pPage->pBt->usableSize );

  if( size<4 ) size = 4;

#ifdef SQLITE_SECURE_DELETE
  /* Overwrite deleted information with zeros when the SECURE_DELETE 
  ** option is enabled at compile-time */
  memset(&data[start], 0, size);
#endif
................................................................................
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.
*/
static void decodeFlags(MemPage *pPage, int flagByte){
  BtShared *pBt;     /* A copy of pPage->pBt */

  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );

  pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
  pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
  pPage->leaf = (flagByte & PTF_LEAF)!=0;
  pPage->childPtrSize = 4*(pPage->leaf==0);
  pBt = pPage->pBt;
  if( flagByte & PTF_LEAFDATA ){
    pPage->leafData = 1;
................................................................................
  int cellOffset;    /* Offset from start of page to first cell pointer */
  int nFree;         /* Number of unused bytes on the page */
  int top;           /* First byte of the cell content area */

  pBt = pPage->pBt;
  assert( pBt!=0 );
  assert( pParent==0 || pParent->pBt==pBt );

  assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
  assert( pPage->aData == &((unsigned char*)pPage)[-pBt->pageSize] );
  if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
    /* The parent page should never change unless the file is corrupt */
    return SQLITE_CORRUPT_BKPT;
  }
  if( pPage->isInit ) return SQLITE_OK;
................................................................................
  BtShared *pBt = pPage->pBt;
  int hdr = pPage->hdrOffset;
  int first;

  assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
  assert( &data[pBt->pageSize] == (unsigned char*)pPage );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  memset(&data[hdr], 0, pBt->usableSize - hdr);
  data[hdr] = flags;
  first = hdr + 8 + 4*((flags&PTF_LEAF)==0);
  memset(&data[hdr+1], 0, 4);
  data[hdr+7] = 0;
  put2byte(&data[hdr+5], pBt->usableSize);
  pPage->nFree = pBt->usableSize - first;
................................................................................
  MemPage **ppPage,    /* Return the page in this parameter */
  int noContent        /* Do not load page content if true */
){
  int rc;
  MemPage *pPage;
  DbPage *pDbPage;


  rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
  if( rc ) return rc;
  pPage = (MemPage *)sqlite3PagerGetExtra(pDbPage);
  pPage->aData = sqlite3PagerGetData(pDbPage);
  pPage->pDbPage = pDbPage;
  pPage->pBt = pBt;
  pPage->pgno = pgno;
................................................................................
static int getAndInitPage(
  BtShared *pBt,          /* The database file */
  Pgno pgno,           /* Number of the page to get */
  MemPage **ppPage,    /* Write the page pointer here */
  MemPage *pParent     /* Parent of the page */
){
  int rc;

  if( pgno==0 ){
    return SQLITE_CORRUPT_BKPT; 
  }
  rc = sqlite3BtreeGetPage(pBt, pgno, ppPage, 0);
  if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
    rc = sqlite3BtreeInitPage(*ppPage, pParent);
  }
................................................................................
** call to sqlite3BtreeGetPage.
*/
static void releasePage(MemPage *pPage){
  if( pPage ){
    assert( pPage->aData );
    assert( pPage->pBt );
    assert( &pPage->aData[pPage->pBt->pageSize]==(unsigned char*)pPage );

    sqlite3PagerUnref(pPage->pDbPage);
  }
}

/*
** This routine is called when the reference count for a page
** reaches zero.  We need to unref the pParent pointer when that
** happens.
*/
static void pageDestructor(DbPage *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage *)sqlite3PagerGetExtra(pData);

  if( pPage->pParent ){
    MemPage *pParent = pPage->pParent;
    pPage->pParent = 0;
    releasePage(pParent);
  }
  pPage->isInit = 0;
}
................................................................................
** This routine needs to reset the extra data section at the end of the
** page to agree with the restored data.
*/
static void pageReinit(DbPage *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage *)sqlite3PagerGetExtra(pData);

  if( pPage->isInit ){
    pPage->isInit = 0;
    sqlite3BtreeInitPage(pPage, pPage->pParent);
  }
}

/*
................................................................................
*/
int sqlite3BtreeOpen(
  const char *zFilename,  /* Name of the file containing the BTree database */
  sqlite3 *pSqlite,       /* Associated database handle */
  Btree **ppBtree,        /* Pointer to new Btree object written here */
  int flags               /* Options */
){
  sqlite3_vfs *pVfs = (pSqlite?pSqlite->pVfs:sqlite3_find_vfs(0));
  BtShared *pBt = 0;      /* Shared part of btree structure */
  Btree *p;               /* Handle to return */
  int rc = SQLITE_OK;
  int nReserve;
  unsigned char zDbHeader[100];








  /* Set the variable isMemdb to true for an in-memory database, or 
  ** false for a file-based database. This symbol is only required if
  ** either of the shared-data or autovacuum features are compiled 
  ** into the library.
  */
#if !defined(SQLITE_OMIT_SHARED_CACHE) || !defined(SQLITE_OMIT_AUTOVACUUM)
  #ifdef SQLITE_OMIT_MEMORYDB
................................................................................
*/
static int removeFromSharingList(BtShared *pBt){
#ifndef SQLITE_OMIT_SHARED_CACHE
  sqlite3_mutex *pMaster;
  BtShared *pList;
  int removed = 0;


  pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(pMaster);
  pBt->nRef--;
  if( pBt->nRef<=0 ){
    if( sqlite3SharedCacheList==pBt ){
      sqlite3SharedCacheList = pBt->pNext;
    }else{
................................................................................
  }
#endif

  sqlite3_free(p);
  return SQLITE_OK;
}

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** 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.
................................................................................
  assert( p->pNext==0 || p->pNext->pSqlite==p->pSqlite );
  assert( p->pPrev==0 || p->pPrev->pSqlite==p->pSqlite );
  assert( p->sharable || (p->pNext==0 && p->pPrev==0) );

  /* Check for locking consistency */
  assert( !p->locked || p->wantToLock>0 );
  assert( p->sharable || p->wantToLock==0 );




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

  /* In most cases, we should be able to acquire the lock we
  ** want without having to go throught the ascending lock
................................................................................
  }
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */

/*
** Exit the recursive mutex on a Btree.
*/
#ifndef SQLITE_OMIT_SHARED_CACHE
void sqlite3BtreeLeave(Btree *p){
  if( p->sharable ){
    assert( p->wantToLock>0 );
    p->wantToLock--;
    if( p->wantToLock==0 ){
      assert( p->locked );
      sqlite3_mutex_leave(p->pBt->mutex);
      p->locked = 0;
    }
  }
}
















#endif /* !SQLITE_OMIT_SHARED_CACHE */

/*
** Change the busy handler callback function.
*/
int sqlite3BtreeSetBusyHandler(Btree *p, BusyHandler *pHandler){
  BtShared *pBt = p->pBt;

  pBt->pBusyHandler = pHandler;
  sqlite3PagerSetBusyhandler(pBt->pPager, pHandler);

  return SQLITE_OK;
}

/*
** Change the limit on the number of pages allowed in the cache.
**
** The maximum number of cache pages is set to the absolute
................................................................................
** an abrupt power failure when synchronous is off, the database
** could be left in an inconsistent and unrecoverable state.
** Synchronous is on by default so database corruption is not
** normally a worry.
*/
int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
  BtShared *pBt = p->pBt;

  sqlite3PagerSetCachesize(pBt->pPager, mxPage);

  return SQLITE_OK;
}

/*
** Change the way data is synced to disk in order to increase or decrease
** how well the database resists damage due to OS crashes and power
** failures.  Level 1 is the same as asynchronous (no syncs() occur and
................................................................................
** there is a high probability of damage)  Level 2 is the default.  There
** is a very low but non-zero probability of damage.  Level 3 reduces the
** probability of damage to near zero but with a write performance reduction.
*/
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
int sqlite3BtreeSetSafetyLevel(Btree *p, int level, int fullSync){
  BtShared *pBt = p->pBt;

  sqlite3PagerSetSafetyLevel(pBt->pPager, level, fullSync);

  return SQLITE_OK;
}
#endif

/*
** Return TRUE if the given btree is set to safety level 1.  In other
** words, return TRUE if no sync() occurs on the disk files.
*/
int sqlite3BtreeSyncDisabled(Btree *p){
  BtShared *pBt = p->pBt;

  assert( pBt && pBt->pPager );

  return sqlite3PagerNosync(pBt->pPager);


}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Change the default pages size and the number of reserved bytes per page.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
................................................................................
** at the beginning of a page.
**
** If parameter nReserve is less than zero, then the number of reserved
** bytes per page is left unchanged.
*/
int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
  BtShared *pBt = p->pBt;

  if( pBt->pageSizeFixed ){

    return SQLITE_READONLY;
  }
  if( nReserve<0 ){
    nReserve = pBt->pageSize - pBt->usableSize;
  }
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    assert( (pageSize & 7)==0 );
    assert( !pBt->pPage1 && !pBt->pCursor );
    pBt->pageSize = sqlite3PagerSetPagesize(pBt->pPager, pageSize);
  }
  pBt->usableSize = pBt->pageSize - nReserve;

  return SQLITE_OK;
}

/*
** Return the currently defined page size
*/
int sqlite3BtreeGetPageSize(Btree *p){
  return p->pBt->pageSize;
}
int sqlite3BtreeGetReserve(Btree *p){


  return p->pBt->pageSize - p->pBt->usableSize;


}

/*
** Set the maximum page count for a database if mxPage is positive.
** No changes are made if mxPage is 0 or negative.
** Regardless of the value of mxPage, return the maximum page count.
*/
int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){


  return sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);


}
#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */

/*
** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
** is disabled. The default value for the auto-vacuum property is 
................................................................................
** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
*/
int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return SQLITE_READONLY;
#else
  BtShared *pBt = p->pBt;

  int av = (autoVacuum?1:0);


  if( pBt->pageSizeFixed && av!=pBt->autoVacuum ){
    return SQLITE_READONLY;
  }

  pBt->autoVacuum = av;


  return SQLITE_OK;
#endif
}

/*
** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
** enabled 1 is returned. Otherwise 0.
*/
int sqlite3BtreeGetAutoVacuum(Btree *p){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return BTREE_AUTOVACUUM_NONE;
#else
  return (


    (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
    (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
    BTREE_AUTOVACUUM_INCR
  );


#endif
}


/*
** Get a reference to pPage1 of the database file.  This will
** also acquire a readlock on that file.
................................................................................
** well-formed database file, then SQLITE_CORRUPT is returned.
** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
** is returned if we run out of memory. 
*/
static int lockBtree(BtShared *pBt){
  int rc, pageSize;
  MemPage *pPage1;


  if( pBt->pPage1 ) return SQLITE_OK;
  rc = sqlite3BtreeGetPage(pBt, 1, &pPage1, 0);
  if( rc!=SQLITE_OK ) return rc;
  

  /* Do some checking to help insure the file we opened really is
  ** a valid database file. 
................................................................................

/*
** This routine works like lockBtree() except that it also invokes the
** busy callback if there is lock contention.
*/
static int lockBtreeWithRetry(Btree *pRef){
  int rc = SQLITE_OK;



  if( pRef->inTrans==TRANS_NONE ){
    u8 inTransaction = pRef->pBt->inTransaction;
    btreeIntegrity(pRef);
    rc = sqlite3BtreeBeginTrans(pRef, 0);
    pRef->pBt->inTransaction = inTransaction;
    pRef->inTrans = TRANS_NONE;
    if( rc==SQLITE_OK ){
................................................................................
** has the effect of releasing the read lock.
**
** If there are any outstanding cursors, this routine is a no-op.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(BtShared *pBt){

  if( pBt->inTransaction==TRANS_NONE && pBt->pCursor==0 && pBt->pPage1!=0 ){
    if( sqlite3PagerRefcount(pBt->pPager)>=1 ){
      if( pBt->pPage1->aData==0 ){
        MemPage *pPage = pBt->pPage1;
        pPage->aData = &((u8*)pPage)[-pBt->pageSize];
        pPage->pBt = pBt;
        pPage->pgno = 1;
................................................................................
** Create a new database by initializing the first page of the
** file.
*/
static int newDatabase(BtShared *pBt){
  MemPage *pP1;
  unsigned char *data;
  int rc;


  if( sqlite3PagerPagecount(pBt->pPager)>0 ) return SQLITE_OK;
  pP1 = pBt->pPage1;
  assert( pP1!=0 );
  data = pP1->aData;
  rc = sqlite3PagerWrite(pP1->pDbPage);
  if( rc ) return rc;
  memcpy(data, zMagicHeader, sizeof(zMagicHeader));
................................................................................
** when A already has a read lock, we encourage A to give up and let B
** proceed.
*/
int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
  BtShared *pBt = p->pBt;
  int rc = SQLITE_OK;


  btreeIntegrity(p);

  /* If the btree is already in a write-transaction, or it
  ** is already in a read-transaction and a read-transaction
  ** is requested, this is a no-op.
  */
  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
    return SQLITE_OK;
  }

  /* Write transactions are not possible on a read-only database */
  if( pBt->readOnly && wrflag ){
    return SQLITE_READONLY;

  }

  /* If another database handle has already opened a write transaction 
  ** on this shared-btree structure and a second write transaction is
  ** requested, return SQLITE_BUSY.
  */
  if( pBt->inTransaction==TRANS_WRITE && wrflag ){
    return SQLITE_BUSY;

  }

  do {
    if( pBt->pPage1==0 ){
      rc = lockBtree(pBt);
    }

................................................................................
    }
    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
    if( p->inTrans>pBt->inTransaction ){
      pBt->inTransaction = p->inTrans;
    }
  }



  btreeIntegrity(p);

  return rc;
}

#ifndef SQLITE_OMIT_AUTOVACUUM

/*
** Set the pointer-map entries for all children of page pPage. Also, if
................................................................................
  int i;                             /* Counter variable */
  int nCell;                         /* Number of cells in page pPage */
  int rc;                            /* Return code */
  BtShared *pBt = pPage->pBt;
  int isInitOrig = pPage->isInit;
  Pgno pgno = pPage->pgno;


  rc = sqlite3BtreeInitPage(pPage, pPage->pParent);
  if( rc!=SQLITE_OK ){
    goto set_child_ptrmaps_out;
  }
  nCell = pPage->nCell;

  for(i=0; i<nCell; i++){
................................................................................
** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
**                   page pointed to by one of the cells on pPage.
**
** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
**                   overflow page in the list.
*/
static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){

  if( eType==PTRMAP_OVERFLOW2 ){
    /* The pointer is always the first 4 bytes of the page in this case.  */
    if( get4byte(pPage->aData)!=iFrom ){
      return SQLITE_CORRUPT_BKPT;
    }
    put4byte(pPage->aData, iTo);
  }else{
................................................................................
  MemPage *pPtrPage;   /* The page that contains a pointer to pDbPage */
  Pgno iDbPage = pDbPage->pgno;
  Pager *pPager = pBt->pPager;
  int rc;

  assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || 
      eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );


  /* Move page iDbPage from it's current location to page number iFreePage */
  TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", 
      iDbPage, iFreePage, iPtrPage, eType));
  rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................
** number of pages the database file will contain after this 
** process is complete.
*/
static int incrVacuumStep(BtShared *pBt, Pgno nFin){
  Pgno iLastPg;             /* Last page in the database */
  Pgno nFreeList;           /* Number of pages still on the free-list */


  iLastPg = pBt->nTrunc;
  if( iLastPg==0 ){
    iLastPg = sqlite3PagerPagecount(pBt->pPager);
  }

  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
    int rc;
................................................................................
** It performs a single unit of work towards an incremental vacuum.
**
** If the incremental vacuum is finished after this function has run,
** SQLITE_DONE is returned. If it is not finished, but no error occured,
** SQLITE_OK is returned. Otherwise an SQLite error code. 
*/
int sqlite3BtreeIncrVacuum(Btree *p){

  BtShared *pBt = p->pBt;


  assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
  if( !pBt->autoVacuum ){
    return SQLITE_DONE;
  }

  invalidateAllOverflowCache(pBt);
  return incrVacuumStep(pBt, 0);



}

/*
** This routine is called prior to sqlite3PagerCommit when a transaction
** is commited for an auto-vacuum database.
**
** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
................................................................................
static int autoVacuumCommit(BtShared *pBt, Pgno *pnTrunc){
  int rc = SQLITE_OK;
  Pager *pPager = pBt->pPager;
#ifndef NDEBUG
  int nRef = sqlite3PagerRefcount(pPager);
#endif


  invalidateAllOverflowCache(pBt);
  assert(pBt->autoVacuum);
  if( !pBt->incrVacuum ){
    Pgno nFin = 0;

    if( pBt->nTrunc==0 ){
      Pgno nFree;
................................................................................
** the write-transaction for this database file is to delete the journal.
*/
int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
  int rc = SQLITE_OK;
  if( p->inTrans==TRANS_WRITE ){
    BtShared *pBt = p->pBt;
    Pgno nTrunc = 0;

#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum ){
      rc = autoVacuumCommit(pBt, &nTrunc); 
      if( rc!=SQLITE_OK ){

        return rc;
      }
    }
#endif
    rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, nTrunc);

  }
  return rc;
}

/*
** Commit the transaction currently in progress.
**
................................................................................
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeCommitPhaseTwo(Btree *p){
  BtShared *pBt = p->pBt;


  btreeIntegrity(p);

  /* If the handle has a write-transaction open, commit the shared-btrees 
  ** transaction and set the shared state to TRANS_READ.
  */
  if( p->inTrans==TRANS_WRITE ){
    int rc;
    assert( pBt->inTransaction==TRANS_WRITE );
    assert( pBt->nTransaction>0 );
    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
    if( rc!=SQLITE_OK ){

      return rc;
    }
    pBt->inTransaction = TRANS_READ;
    pBt->inStmt = 0;
  }
  unlockAllTables(p);

................................................................................
  /* Set the handles current transaction state to TRANS_NONE and unlock
  ** the pager if this call closed the only read or write transaction.
  */
  p->inTrans = TRANS_NONE;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);

  return SQLITE_OK;
}

/*
** Do both phases of a commit.
*/
int sqlite3BtreeCommit(Btree *p){
  int rc;

  rc = sqlite3BtreeCommitPhaseOne(p, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeCommitPhaseTwo(p);
  }

  return rc;
}

#ifndef NDEBUG
/*
** Return the number of write-cursors open on this handle. This is for use
** in assert() expressions, so it is only compiled if NDEBUG is not
................................................................................
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeRollback(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  MemPage *pPage1;


  rc = saveAllCursors(pBt, 0, 0);
#ifndef SQLITE_OMIT_SHARED_CACHE
  if( rc!=SQLITE_OK ){
    /* This is a horrible situation. An IO or malloc() error occured whilst
    ** trying to save cursor positions. If this is an automatic rollback (as
    ** the result of a constraint, malloc() failure or IO error) then 
    ** the cache may be internally inconsistent (not contain valid trees) so
................................................................................
  }

  p->inTrans = TRANS_NONE;
  pBt->inStmt = 0;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);

  return rc;
}

/*
** Start a statement subtransaction.  The subtransaction can
** can be rolled back independently of the main transaction.
** You must start a transaction before starting a subtransaction.
................................................................................
** that are contained within a BEGIN...COMMIT block.  If a constraint
** error occurs within the statement, the effect of that one statement
** can be rolled back without having to rollback the entire transaction.
*/
int sqlite3BtreeBeginStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;

  if( (p->inTrans!=TRANS_WRITE) || pBt->inStmt ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }

  assert( pBt->inTransaction==TRANS_WRITE );
  rc = pBt->readOnly ? SQLITE_OK : sqlite3PagerStmtBegin(pBt->pPager);
  pBt->inStmt = 1;


  return rc;
}


/*
** Commit the statment subtransaction currently in progress.  If no
** subtransaction is active, this is a no-op.
*/
int sqlite3BtreeCommitStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;

  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3PagerStmtCommit(pBt->pPager);
  }else{
    rc = SQLITE_OK;
  }
  pBt->inStmt = 0;

  return rc;
}

/*
** Rollback the active statement subtransaction.  If no subtransaction
** is active this routine is a no-op.
**
................................................................................
** All cursors will be invalidated by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqlite3BtreeRollbackStmt(Btree *p){
  int rc = SQLITE_OK;
  BtShared *pBt = p->pBt;

  sqlite3MallocDisallow();
  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3PagerStmtRollback(pBt->pPager);
    assert( countWriteCursors(pBt)==0 );
    pBt->inStmt = 0;
  }
  sqlite3MallocAllow();

  return rc;
}

/*
** Default key comparison function to be used if no comparison function
** is specified on the sqlite3BtreeCursor() call.
*/
................................................................................
**
** The comparison function must be logically the same for every cursor
** on a particular table.  Changing the comparison function will result
** in incorrect operations.  If the comparison function is NULL, a
** default comparison function is used.  The comparison function is
** always ignored for INTKEY tables.
*/
int sqlite3BtreeCursor(
  Btree *p,                                   /* The btree */
  int iTable,                                 /* Root page of table to open */
  int wrFlag,                                 /* 1 to write. 0 read-only */
  int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
  void *pArg,                                 /* First arg to xCompare() */
  BtCursor **ppCur                            /* Write new cursor here */
){
  int rc;
  BtCursor *pCur;
  BtShared *pBt = p->pBt;


  *ppCur = 0;
  if( wrFlag ){
    if( pBt->readOnly ){
      return SQLITE_READONLY;
    }
    if( checkReadLocks(p, iTable, 0) ){
      return SQLITE_LOCKED;
................................................................................
    pCur->pNext->pPrev = pCur;
  }
  pBt->pCursor = pCur;
  pCur->eState = CURSOR_INVALID;
  *ppCur = pCur;

  return SQLITE_OK;

create_cursor_exception:
  if( pCur ){
    releasePage(pCur->pPage);
    sqlite3_free(pCur);
  }
  unlockBtreeIfUnused(pBt);
  return rc;
}
















/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
int sqlite3BtreeCloseCursor(BtCursor *pCur){
  BtShared *pBt = pCur->pBtree->pBt;


  clearCursorPosition(pCur);
  if( pCur->pPrev ){
    pCur->pPrev->pNext = pCur->pNext;
  }else{
    pBt->pCursor = pCur->pNext;
  }
  if( pCur->pNext ){
    pCur->pNext->pPrev = pCur->pPrev;
  }
  releasePage(pCur->pPage);
  unlockBtreeIfUnused(pBt);
  invalidateOverflowCache(pCur);

  sqlite3_free(pCur);
  return SQLITE_OK;
}

/*
** Make a temporary cursor by filling in the fields of pTempCur.
** The temporary cursor is not on the cursor list for the Btree.
*/
void sqlite3BtreeGetTempCursor(BtCursor *pCur, BtCursor *pTempCur){
  memcpy(pTempCur, pCur, sizeof(*pCur));
  pTempCur->pNext = 0;
  pTempCur->pPrev = 0;
  if( pTempCur->pPage ){

    sqlite3PagerRef(pTempCur->pPage->pDbPage);

  }
}

/*
** Delete a temporary cursor such as was made by the CreateTemporaryCursor()
** function above.
*/
void sqlite3BtreeReleaseTempCursor(BtCursor *pCur){
  if( pCur->pPage ){

    sqlite3PagerUnref(pCur->pPage->pDbPage);

  }
}

/*
** Make sure the BtCursor* given in the argument has a valid
** BtCursor.info structure.  If it is not already valid, call
** sqlite3BtreeParseCell() to fill it in.
................................................................................
** the key for the current entry.  If the cursor is not pointing
** to a valid entry, *pSize is set to 0. 
**
** For a table with the INTKEY flag set, this routine returns the key
** itself, not the number of bytes in the key.
*/
int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){



  int rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nKey;
    }
  }

  return rc;
}

/*
** 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 sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){



  int rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      /* Not pointing at a valid entry - set *pSize to 0. */
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nData;
    }
  }

  return rc;
}

/*
** Given the page number of an overflow page in the database (parameter
** ovfl), this function finds the page number of the next page in the 
** linked list of overflow pages. If possible, it uses the auto-vacuum
................................................................................
  Pgno ovfl,                   /* Overflow page */
  MemPage **ppPage,            /* OUT: MemPage handle */
  Pgno *pPgnoNext              /* OUT: Next overflow page number */
){
  Pgno next = 0;
  int rc;


  /* One of these must not be NULL. Otherwise, why call this function? */
  assert(ppPage || pPgnoNext);

  /* If pPgnoNext is NULL, then this function is being called to obtain
  ** a MemPage* reference only. No page-data is required in this case.
  */
  if( !pPgnoNext ){
................................................................................
  MemPage *pPage = pCur->pPage;        /* Btree page of current cursor entry */
  BtShared *pBt = pCur->pBtree->pBt;   /* Btree this cursor belongs to */

  assert( pPage );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  assert( offset>=0 );


  getCellInfo(pCur);
  aPayload = pCur->info.pCell + pCur->info.nHeader;
  nKey = (pPage->intKey ? 0 : pCur->info.nKey);

  if( skipKey ){
    offset += nKey;
................................................................................
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){



  int rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    if( pCur->pPage->intKey ){

      return SQLITE_CORRUPT_BKPT;
    }
    assert( pCur->pPage->intKey==0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0, 0);
  }

  return rc;
}

/*
** Read part of the data associated with cursor pCur.  Exactly
** "amt" bytes will be transfered into pBuf[].  The transfer
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){



  int rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = accessPayload(pCur, offset, amt, pBuf, 1, 0);
  }

  return rc;
}

/*
** Return a pointer to payload information from the entry that the 
** pCur cursor is pointing to.  The pointer is to the beginning of
** the key if skipKey==0 and it points to the beginning of data if
................................................................................
  unsigned char *aPayload;
  MemPage *pPage;
  u32 nKey;
  int nLocal;

  assert( pCur!=0 && pCur->pPage!=0 );
  assert( pCur->eState==CURSOR_VALID );

  pPage = pCur->pPage;
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  getCellInfo(pCur);
  aPayload = pCur->info.pCell;
  aPayload += pCur->info.nHeader;
  if( pPage->intKey ){
    nKey = 0;
................................................................................

/*
** For the entry that cursor pCur is point to, return as
** many bytes of the key or data as are available on the local
** b-tree page.  Write the number of available bytes into *pAmt.
**
** The pointer returned is ephemeral.  The key/data may move
** or be destroyed on the next call to any Btree routine.



**
** These routines is used to get quick access to key and data
** in the common case where no overflow pages are used.
*/
const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){

  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 0);
  }
  return 0;
}
const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){

  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 1);
  }
  return 0;
}


................................................................................
*/
static int moveToChild(BtCursor *pCur, u32 newPgno){
  int rc;
  MemPage *pNewPage;
  MemPage *pOldPage;
  BtShared *pBt = pCur->pBtree->pBt;


  assert( pCur->eState==CURSOR_VALID );
  rc = getAndInitPage(pBt, newPgno, &pNewPage, pCur->pPage);
  if( rc ) return rc;
  pNewPage->idxParent = pCur->idx;
  pOldPage = pCur->pPage;
  pOldPage->idxShift = 0;
  releasePage(pOldPage);
................................................................................
** The virtual root page is the root page for most tables.  But
** for the table rooted on page 1, sometime the real root page
** is empty except for the right-pointer.  In such cases the
** virtual root page is the page that the right-pointer of page
** 1 is pointing to.
*/
int sqlite3BtreeIsRootPage(MemPage *pPage){



  MemPage *pParent = pPage->pParent;
  if( pParent==0 ) return 1;
  if( pParent->pgno>1 ) return 0;
  if( get2byte(&pParent->aData[pParent->hdrOffset+3])==0 ) return 1;
  return 0;
}

/*
................................................................................
** the largest cell index.
*/
void sqlite3BtreeMoveToParent(BtCursor *pCur){
  MemPage *pParent;
  MemPage *pPage;
  int idxParent;


  assert( pCur->eState==CURSOR_VALID );
  pPage = pCur->pPage;
  assert( pPage!=0 );
  assert( !sqlite3BtreeIsRootPage(pPage) );
  pParent = pPage->pParent;
  assert( pParent!=0 );
  idxParent = pPage->idxParent;
  sqlite3PagerRef(pParent->pDbPage);
  releasePage(pPage);
  pCur->pPage = pParent;
  pCur->info.nSize = 0;
  assert( pParent->idxShift==0 );
  pCur->idx = idxParent;

}

/*
** Move the cursor to the root page
*/
static int moveToRoot(BtCursor *pCur){
  MemPage *pRoot;
  int rc = SQLITE_OK;

  BtShared *pBt = pCur->pBtree->pBt;



  if( pCur->eState==CURSOR_REQUIRESEEK ){
    clearCursorPosition(pCur);
  }
  pRoot = pCur->pPage;
  if( pRoot && pRoot->pgno==pCur->pgnoRoot ){
    assert( pRoot->isInit );
  }else{
................................................................................
** entry to which it is currently pointing.
**
** The left-most leaf is the one with the smallest key - the first
** in ascending order.
*/
static int moveToLeftmost(BtCursor *pCur){
  Pgno pgno;
  int rc;
  MemPage *pPage;



  assert( pCur->eState==CURSOR_VALID );
  while( !(pPage = pCur->pPage)->leaf ){
    assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
    pgno = get4byte(findCell(pPage, pCur->idx));
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
  }
  return SQLITE_OK;
}

/*
** Move the cursor down to the right-most leaf entry beneath the
** page to which it is currently pointing.  Notice the difference
** between moveToLeftmost() and moveToRightmost().  moveToLeftmost()
** finds the left-most entry beneath the *entry* whereas moveToRightmost()
................................................................................
** finds the right-most entry beneath the *page*.
**
** The right-most entry is the one with the largest key - the last
** key in ascending order.
*/
static int moveToRightmost(BtCursor *pCur){
  Pgno pgno;
  int rc;
  MemPage *pPage;



  assert( pCur->eState==CURSOR_VALID );
  while( !(pPage = pCur->pPage)->leaf ){
    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    pCur->idx = pPage->nCell;
    rc = moveToChild(pCur, pgno);
    if( rc ) return rc;
  }

  pCur->idx = pPage->nCell - 1;
  pCur->info.nSize = 0;

  return SQLITE_OK;
}

/* Move the cursor to the first entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
  int rc;



  rc = moveToRoot(pCur);
  if( rc ) return rc;

  if( pCur->eState==CURSOR_INVALID ){
    assert( pCur->pPage->nCell==0 );
    *pRes = 1;
    return SQLITE_OK;
  }

  assert( pCur->pPage->nCell>0 );
  *pRes = 0;
  rc = moveToLeftmost(pCur);


  return rc;
}

/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
  int rc;



  rc = moveToRoot(pCur);
  if( rc ) return rc;

  if( CURSOR_INVALID==pCur->eState ){
    assert( pCur->pPage->nCell==0 );
    *pRes = 1;
    return SQLITE_OK;
  }

  assert( pCur->eState==CURSOR_VALID );
  *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
................................................................................
**                  and the cursor is therefore left point to nothing.
**
**     *pRes==0     The cursor is left pointing at an entry that
**                  exactly matches pKey.
**
**     *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;



  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;
  }
................................................................................
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
        }else{
          pCellKey = sqlite3_malloc( nCellKey );
          if( pCellKey==0 ) return SQLITE_NOMEM;
          rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
          sqlite3_free(pCellKey);

          if( rc ) return rc;

        }
      }
      if( c==0 ){
        if( pPage->leafData && !pPage->leaf ){
          lwr = pCur->idx;
          upr = lwr - 1;
          break;
................................................................................
    rc = moveToChild(pCur, chldPg);
    if( rc ){
      return rc;
    }
  }
  /* NOT REACHED */
}


/*
** Return TRUE if the cursor is not pointing at an entry of the table.
**
** TRUE will be returned after a call to sqlite3BtreeNext() moves
** past the last entry in the table or sqlite3BtreePrev() moves past
** the first entry.  TRUE is also returned if the table is empty.
................................................................................

/*
** 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 sqlite3BtreeNext(BtCursor *pCur, int *pRes){
  int rc;
  MemPage *pPage;

  rc = restoreOrClearCursorPosition(pCur);
  if( rc!=SQLITE_OK ){
    return rc;
  }
................................................................................
      *pRes = 0;
      return rc;
    }
    do{
      if( sqlite3BtreeIsRootPage(pPage) ){
        *pRes = 1;
        pCur->eState = CURSOR_INVALID;

        return SQLITE_OK;
      }
      sqlite3BtreeMoveToParent(pCur);
      pPage = pCur->pPage;
    }while( pCur->idx>=pPage->nCell );
    *pRes = 0;
    if( pPage->leafData ){
................................................................................
  *pRes = 0;
  if( pPage->leaf ){
    return SQLITE_OK;
  }
  rc = moveToLeftmost(pCur);
  return rc;
}









/*
** Step the cursor to the back to the previous entry in the database.  If
** successful 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.
*/
int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
  int rc;
  Pgno pgno;
  MemPage *pPage;

  rc = restoreOrClearCursorPosition(pCur);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................

  pPage = pCur->pPage;
  assert( pPage->isInit );
  assert( pCur->idx>=0 );
  if( !pPage->leaf ){
    pgno = get4byte( findCell(pPage, pCur->idx) );
    rc = moveToChild(pCur, pgno);

    if( rc ) return rc;

    rc = moveToRightmost(pCur);
  }else{
    while( pCur->idx==0 ){
      if( sqlite3BtreeIsRootPage(pPage) ){
        pCur->eState = CURSOR_INVALID;
        *pRes = 1;
        return SQLITE_OK;
................................................................................
      rc = sqlite3BtreePrevious(pCur, pRes);
    }else{
      rc = SQLITE_OK;
    }
  }
  *pRes = 0;
  return rc;







}

/*
** Allocate a new page from the database file.
**
** The new page is marked as dirty.  (In other words, sqlite3PagerWrite()
** has already been called on the new page.)  The new page has also
................................................................................
  MemPage *pPage1;
  int rc;
  int n;     /* Number of pages on the freelist */
  int k;     /* Number of leaves on the trunk of the freelist */
  MemPage *pTrunk = 0;
  MemPage *pPrevTrunk = 0;


  pPage1 = pBt->pPage1;
  n = get4byte(&pPage1->aData[36]);
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
    
................................................................................
*/
static int freePage(MemPage *pPage){
  BtShared *pBt = pPage->pBt;
  MemPage *pPage1 = pBt->pPage1;
  int rc, n, k;

  /* Prepare the page for freeing */

  assert( pPage->pgno>1 );
  pPage->isInit = 0;
  releasePage(pPage->pParent);
  pPage->pParent = 0;

  /* Increment the free page count on pPage1 */
  rc = sqlite3PagerWrite(pPage1->pDbPage);
................................................................................
  BtShared *pBt = pPage->pBt;
  CellInfo info;
  Pgno ovflPgno;
  int rc;
  int nOvfl;
  int ovflPageSize;


  sqlite3BtreeParseCellPtr(pPage, pCell, &info);
  if( info.iOverflow==0 ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  ovflPgno = get4byte(&pCell[info.iOverflow]);
  ovflPageSize = pBt->usableSize - 4;
  nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
................................................................................
  MemPage *pToRelease = 0;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  int nHeader;
  CellInfo info;



  /* Fill in the header. */
  nHeader = 0;
  if( !pPage->leaf ){
    nHeader += 4;
  }
  if( pPage->hasData ){
................................................................................
** given in the second argument so that MemPage.pParent holds the
** pointer in the third argument.
*/
static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
  MemPage *pThis;
  DbPage *pDbPage;


  assert( pNewParent!=0 );
  if( pgno==0 ) return SQLITE_OK;
  assert( pBt->pPager!=0 );
  pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
  if( pDbPage ){
    pThis = (MemPage *)sqlite3PagerGetExtra(pDbPage);
    if( pThis->isInit ){
................................................................................
** another.
*/
static int reparentChildPages(MemPage *pPage){
  int i;
  BtShared *pBt = pPage->pBt;
  int rc = SQLITE_OK;


  if( pPage->leaf ) return SQLITE_OK;

  for(i=0; i<pPage->nCell; i++){
    u8 *pCell = findCell(pPage, i);
    if( !pPage->leaf ){
      rc = reparentPage(pBt, get4byte(pCell), pPage, i);
      if( rc!=SQLITE_OK ) return rc;
................................................................................
  int pc;         /* Offset to cell content of cell being deleted */
  u8 *data;       /* pPage->aData */
  u8 *ptr;        /* Used to move bytes around within data[] */

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  data = pPage->aData;
  ptr = &data[pPage->cellOffset + 2*idx];
  pc = get2byte(ptr);
  assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
  freeSpace(pPage, pc, sz);
  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
    ptr[0] = ptr[2];
................................................................................
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  u8 *ptr;          /* Used for moving information around in data[] */

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( sz==cellSizePtr(pPage, pCell) );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );

  if( pPage->nOverflow || sz+2>pPage->nFree ){
    if( pTemp ){
      memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
      pCell = pTemp;
    }
    j = pPage->nOverflow++;
    assert( j<sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0]) );
................................................................................
  int totalSize;    /* Total size of all cells */
  int hdr;          /* Index of page header */
  int cellptr;      /* Address of next cell pointer */
  int cellbody;     /* Address of next cell body */
  u8 *data;         /* Data for the page */

  assert( pPage->nOverflow==0 );

  totalSize = 0;
  for(i=0; i<nCell; i++){
    totalSize += aSize[i];
  }
  assert( totalSize+2*nCell<=pPage->nFree );
  assert( pPage->nCell==0 );
  cellptr = pPage->cellOffset;
................................................................................
  u8 *pCell;
  int szCell;
  CellInfo info;
  BtShared *pBt = pPage->pBt;
  int parentIdx = pParent->nCell;   /* pParent new divider cell index */
  int parentSize;                   /* Size of new divider cell */
  u8 parentCell[64];                /* Space for the new divider cell */



  /* Allocate a new page. Insert the overflow cell from pPage
  ** into it. Then remove the overflow cell from pPage.
  */
  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................
  u8 **apCell = 0;             /* All cells begin balanced */
  int *szCell;                 /* Local size of all cells in apCell[] */
  u8 *aCopy[NB];               /* Space for holding data of apCopy[] */
  u8 *aSpace;                  /* Space to hold copies of dividers cells */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 *aFrom = 0;
#endif



  /* 
  ** Find the parent page.
  */
  assert( pPage->isInit );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  pBt = pPage->pBt;
................................................................................
  BtShared *pBt;                  /* The main BTree structure */
  int mxCellPerPage;           /* Maximum number of cells per page */
  u8 **apCell;                 /* All cells from pages being balanced */
  int *szCell;                 /* Local size of all cells */

  assert( pPage->pParent==0 );
  assert( pPage->nCell==0 );

  pBt = pPage->pBt;
  mxCellPerPage = MX_CELL(pBt);
  apCell = sqlite3_malloc( mxCellPerPage*(sizeof(u8*)+sizeof(int)) );
  if( apCell==0 ) return SQLITE_NOMEM;
  szCell = (int*)&apCell[mxCellPerPage];
  if( pPage->leaf ){
    /* The table is completely empty */
................................................................................
  u8 *cdata;          /* Content of the child page */
  int hdr;            /* Offset to page header in parent */
  int brk;            /* Offset to content of first cell in parent */

  assert( pPage->pParent==0 );
  assert( pPage->nOverflow>0 );
  pBt = pPage->pBt;

  rc = allocateBtreePage(pBt, &pChild, &pgnoChild, pPage->pgno, 0);
  if( rc ) return rc;
  assert( sqlite3PagerIswriteable(pChild->pDbPage) );
  usableSize = pBt->usableSize;
  data = pPage->aData;
  hdr = pPage->hdrOffset;
  brk = get2byte(&data[hdr+5]);
................................................................................

/*
** Decide if the page pPage needs to be balanced.  If balancing is
** required, call the appropriate balancing routine.
*/
static int balance(MemPage *pPage, int insert){
  int rc = SQLITE_OK;

  if( pPage->pParent==0 ){
    if( pPage->nOverflow>0 ){
      rc = balance_deeper(pPage);
    }
    if( rc==SQLITE_OK && pPage->nCell==0 ){
      rc = balance_shallower(pPage);
    }
................................................................................
** a page entirely and we do not want to leave any cursors 
** pointing to non-existant pages or cells.
*/
static int checkReadLocks(Btree *pBtree, Pgno pgnoRoot, BtCursor *pExclude){
  BtCursor *p;
  BtShared *pBt = pBtree->pBt;
  sqlite3 *db = pBtree->pSqlite;


  for(p=pBt->pCursor; p; p=p->pNext){
    if( p==pExclude ) continue;
    if( p->eState!=CURSOR_VALID ) continue;
    if( p->pgnoRoot!=pgnoRoot ) continue;
    if( p->wrFlag==0 ){
      sqlite3 *dbOther = p->pBtree->pSqlite;
      if( dbOther==0 ||
................................................................................
  int nZero,                     /* Number of extra 0 bytes to append to data */
  int appendBias                 /* True if this is likely an append */
){
  int rc;
  int loc;
  int szNew;
  MemPage *pPage;

  BtShared *pBt = pCur->pBtree->pBt;
  unsigned char *oldCell;
  unsigned char *newCell = 0;


  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction before doing an insert */
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;


  }
  assert( !pBt->readOnly );
  if( !pCur->wrFlag ){

    return SQLITE_PERM;   /* Cursor not open for writing */
  }
  if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){

    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* 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 );
  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );
  rc = sqlite3PagerWrite(pPage->pDbPage);


  if( rc ) return rc;

  newCell = sqlite3_malloc( MX_CELL_SIZE(pBt) );
  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) );
  if( loc==0 && CURSOR_VALID==pCur->eState ){
................................................................................
  /* sqlite3BtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */
  /* fflush(stdout); */
  if( rc==SQLITE_OK ){
    moveToRoot(pCur);
  }
end_insert:
  sqlite3_free(newCell);

  return rc;
}

/*
** Delete the entry that the cursor is pointing to.  The cursor
** is left pointing at a random location.
*/
int sqlite3BtreeDelete(BtCursor *pCur){
  MemPage *pPage = pCur->pPage;
  unsigned char *pCell;
  int rc;
  Pgno pgnoChild = 0;

  BtShared *pBt = pCur->pBtree->pBt;


  assert( pPage->isInit );
  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction before doing a delete */
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;


  }
  assert( !pBt->readOnly );
  if( pCur->idx >= pPage->nCell ){

    return SQLITE_ERROR;  /* The cursor is not pointing to anything */
  }
  if( !pCur->wrFlag ){

    return SQLITE_PERM;   /* Did not open this cursor for writing */
  }
  if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){

    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* Restore the current cursor position (a no-op if the cursor is not in 
  ** CURSOR_REQUIRESEEK state) and save the positions of any other cursors 
  ** open on the same table. Then call sqlite3PagerWrite() on the page
  ** that the entry will be deleted from.
  */
  if( 
    (rc = restoreOrClearCursorPosition(pCur))!=0 ||
    (rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur))!=0 ||
    (rc = sqlite3PagerWrite(pPage->pDbPage))!=0
  ){

    return rc;
  }

  /* Locate the cell within it's page and leave pCell pointing to the
  ** data. The clearCell() call frees any overflow pages associated with the
  ** cell. The cell itself is still intact.
  */
  pCell = findCell(pPage, pCur->idx);
  if( !pPage->leaf ){
    pgnoChild = get4byte(pCell);
  }
  rc = clearCell(pPage, pCell);


  if( rc ) return rc;


  if( !pPage->leaf ){
    /*
    ** The entry we are about to delete is not a leaf so if we do not
    ** do something we will leave a hole on an internal page.
    ** 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
................................................................................
       pCur->pgnoRoot, pPage->pgno));
    dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
    rc = balance(pPage, 0);
  }
  if( rc==SQLITE_OK ){
    moveToRoot(pCur);
  }

  return rc;
}

/*
** Create a new BTree table.  Write into *piTable the page
** number for the root page of the new table.
**
................................................................................
** The type of type is determined by the flags parameter.  Only the
** following values of flags are currently in use.  Other values for
** flags might not work:
**
**     BTREE_INTKEY|BTREE_LEAFDATA     Used for SQL tables with rowid keys
**     BTREE_ZERODATA                  Used for SQL indices
*/
int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
  BtShared *pBt = p->pBt;
  MemPage *pRoot;
  Pgno pgnoRoot;
  int rc;

  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction first */
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;

  }
  assert( !pBt->readOnly );

#ifdef SQLITE_OMIT_AUTOVACUUM
  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);

  if( rc ) return rc;

#else
  if( pBt->autoVacuum ){
    Pgno pgnoMove;      /* Move a page here to make room for the root-page */
    MemPage *pPageMove; /* The page to move to. */

    /* Creating a new table may probably require moving an existing database
    ** to make room for the new tables root page. In case this page turns
................................................................................
    invalidateAllOverflowCache(pBt);

    /* Read the value of meta[3] from the database to determine where the
    ** root page of the new table should go. meta[3] is the largest root-page
    ** created so far, so the new root-page is (meta[3]+1).
    */
    rc = sqlite3BtreeGetMeta(p, 4, &pgnoRoot);
    if( rc!=SQLITE_OK ) return rc;


    pgnoRoot++;

    /* The new root-page may not be allocated on a pointer-map page, or the
    ** PENDING_BYTE page.
    */
    if( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
        pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
................................................................................
#endif
  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
  zeroPage(pRoot, flags | PTF_LEAF);
  sqlite3PagerUnref(pRoot->pDbPage);
  *piTable = (int)pgnoRoot;
  return SQLITE_OK;
}








/*
** Erase the given database page and all its children.  Return
** the page to the freelist.
*/
static int clearDatabasePage(
  BtShared *pBt,           /* The BTree that contains the table */
................................................................................
  int freePageFlag      /* Deallocate page if true */
){
  MemPage *pPage = 0;
  int rc;
  unsigned char *pCell;
  int i;


  if( pgno>sqlite3PagerPagecount(pBt->pPager) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage, pParent);
  if( rc ) goto cleardatabasepage_out;
  for(i=0; i<pPage->nCell; i++){
................................................................................
** This routine will fail with SQLITE_LOCKED if there are any open
** read cursors on the table.  Open write cursors are moved to the
** root of the table.
*/
int sqlite3BtreeClearTable(Btree *p, int iTable){
  int rc;
  BtShared *pBt = p->pBt;

  if( p->inTrans!=TRANS_WRITE ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }
  rc = checkReadLocks(p, iTable, 0);
  if( rc ){
    return rc;



  }

  /* Save the position of all cursors open on this table */
  if( SQLITE_OK!=(rc = saveAllCursors(pBt, iTable, 0)) ){

    return rc;
  }

  return clearDatabasePage(pBt, (Pgno)iTable, 0, 0);
}

/*
** Erase all information in a table and add the root of the table to
** the freelist.  Except, the root of the principle table (the one on
** page 1) is never added to the freelist.
**
................................................................................
** root pages are kept at the beginning of the database file, which
** is necessary for AUTOVACUUM to work right.  *piMoved is set to the 
** page number that used to be the last root page in the file before
** the move.  If no page gets moved, *piMoved is set to 0.
** The last root page is recorded in meta[3] and the value of
** meta[3] is updated by this procedure.
*/
int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
  int rc;
  MemPage *pPage = 0;
  BtShared *pBt = p->pBt;


  if( p->inTrans!=TRANS_WRITE ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }

  /* It is illegal to drop a table if any cursors are open on the
  ** database. This is because in auto-vacuum mode the backend may
  ** need to move another root-page to fill a gap left by the deleted
................................................................................
  }else{
    /* If sqlite3BtreeDropTable was called on page 1. */
    zeroPage(pPage, PTF_INTKEY|PTF_LEAF );
    releasePage(pPage);
  }
  return rc;  
}









/*
** Read the meta-information out of a database file.  Meta[0]
** is the number of free pages currently in the database.  Meta[1]
** through meta[15] are available for use by higher layers.  Meta[0]
** is read-only, the others are read/write.
................................................................................
** free pages is not visible.  So Cookie[0] is the same as Meta[1].
*/
int sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
  DbPage *pDbPage;
  int rc;
  unsigned char *pP1;
  BtShared *pBt = p->pBt;



  /* Reading a meta-data value requires a read-lock on page 1 (and hence
  ** the sqlite_master table. We grab this lock regardless of whether or
  ** not the SQLITE_ReadUncommitted flag is set (the table rooted at page
  ** 1 is treated as a special case by queryTableLock() and lockTable()).
  */
  rc = queryTableLock(p, 1, READ_LOCK);
  if( rc!=SQLITE_OK ){

    return rc;
  }

  assert( idx>=0 && idx<=15 );
  rc = sqlite3PagerGet(pBt->pPager, 1, &pDbPage);


  if( rc ) return rc;

  pP1 = (unsigned char *)sqlite3PagerGetData(pDbPage);
  *pMeta = get4byte(&pP1[36 + idx*4]);
  sqlite3PagerUnref(pDbPage);

  /* If autovacuumed is disabled in this build but we are trying to 
  ** access an autovacuumed database, then make the database readonly. 
  */
#ifdef SQLITE_OMIT_AUTOVACUUM
  if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
#endif

  /* Grab the read-lock on page 1. */
  rc = lockTable(p, 1, READ_LOCK);

  return rc;
}

/*
** Write meta-information back into the database.  Meta[0] is
** read-only and may not be written.
*/
int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
  BtShared *pBt = p->pBt;
  unsigned char *pP1;
  int rc;
  assert( idx>=1 && idx<=15 );

  if( p->inTrans!=TRANS_WRITE ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }

  assert( pBt->pPage1!=0 );
  pP1 = pBt->pPage1->aData;
  rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
  if( rc ) return rc;

  put4byte(&pP1[36 + idx*4], iMeta);
  if( idx==7 ){
    assert( pBt->autoVacuum || iMeta==0 );
    assert( iMeta==0 || iMeta==1 );
    pBt->incrVacuum = iMeta;
  }



  return SQLITE_OK;
}

/*
** Return the flag byte at the beginning of the page that the cursor
** is currently pointing to.
*/
int sqlite3BtreeFlags(BtCursor *pCur){
  /* TODO: What about CURSOR_REQUIRESEEK state? Probably need to call
  ** restoreOrClearCursorPosition() here.
  */
  MemPage *pPage = pCur->pPage;

  return pPage ? pPage->aData[pPage->hdrOffset] : 0;
}


/*
** Return the pager associated with a BTree.  This routine is used for
** testing and debugging only.
*/
Pager *sqlite3BtreePager(Btree *p){


  return p->pBt->pPager;
}

#ifndef SQLITE_OMIT_INTEGRITY_CHECK
/*
** Append a message to the error message string.
*/
................................................................................
  int *pnErr    /* Write number of errors seen to this variable */
){
  int i;
  int nRef;
  IntegrityCk sCheck;
  BtShared *pBt = p->pBt;


  nRef = sqlite3PagerRefcount(pBt->pPager);
  if( lockBtreeWithRetry(p)!=SQLITE_OK ){

    return sqlite3StrDup("Unable to acquire a read lock on the database");
  }
  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = sqlite3PagerPagecount(sCheck.pPager);
  sCheck.mxErr = mxErr;
  sCheck.nErr = 0;
................................................................................
#ifndef SQLITE_OMIT_AUTOVACUUM
  if( pBt->nTrunc!=0 ){
    sCheck.nPage = pBt->nTrunc;
  }
#endif
  if( sCheck.nPage==0 ){
    unlockBtreeIfUnused(pBt);

    return 0;
  }
  sCheck.anRef = sqlite3_malloc( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
  if( !sCheck.anRef ){
    unlockBtreeIfUnused(pBt);
    *pnErr = 1;

    return sqlite3MPrintf(p->pSqlite, "Unable to malloc %d bytes", 
        (sCheck.nPage+1)*sizeof(sCheck.anRef[0]));
  }
  for(i=0; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
  i = PENDING_BYTE_PAGE(pBt);
  if( i<=sCheck.nPage ){
    sCheck.anRef[i] = 1;
................................................................................
      "Outstanding page count goes from %d to %d during this analysis",
      nRef, sqlite3PagerRefcount(pBt->pPager)
    );
  }

  /* Clean  up and report errors.
  */

  sqlite3_free(sCheck.anRef);
  *pnErr = sCheck.nErr;
  return sCheck.zErrMsg;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/*
** Return the full pathname of the underlying database file.
*/
const char *sqlite3BtreeGetFilename(Btree *p){
  assert( p->pBt->pPager!=0 );

  return sqlite3PagerFilename(p->pBt->pPager);
}

/*
** Return the pathname of the directory that contains the database file.
*/
const char *sqlite3BtreeGetDirname(Btree *p){
  assert( p->pBt->pPager!=0 );

  return sqlite3PagerDirname(p->pBt->pPager);
}

/*
** Return the pathname of the journal file for this database. The return
** value of this routine is the same regardless of whether the journal file
** has been created or not.
*/
const char *sqlite3BtreeGetJournalname(Btree *p){
  assert( p->pBt->pPager!=0 );

  return sqlite3PagerJournalname(p->pBt->pPager);
}

#ifndef SQLITE_OMIT_VACUUM
/*
** Copy the complete content of pBtFrom into pBtTo.  A transaction
** must be active for both files.
**
** The size of file pBtFrom may be reduced by this operation.
** If anything goes wrong, the transaction on pBtFrom is rolled back.
*/
int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
  int rc = SQLITE_OK;
  Pgno i, nPage, nToPage, iSkip;

  BtShared *pBtTo = pTo->pBt;
  BtShared *pBtFrom = pFrom->pBt;

  if( pTo->inTrans!=TRANS_WRITE || pFrom->inTrans!=TRANS_WRITE ){
................................................................................
  }

  if( rc ){
    sqlite3BtreeRollback(pTo);
  }
  return rc;  
}










#endif /* SQLITE_OMIT_VACUUM */

/*
** Return non-zero if a transaction is active.
*/
int sqlite3BtreeIsInTrans(Btree *p){


  return (p && (p->inTrans==TRANS_WRITE));
}

/*
** Return non-zero if a statement transaction is active.
*/
int sqlite3BtreeIsInStmt(Btree *p){


  return (p->pBt && p->pBt->inStmt);
}

/*
** Return non-zero if a read (or write) transaction is active.
*/
int sqlite3BtreeIsInReadTrans(Btree *p){


  return (p && (p->inTrans!=TRANS_NONE));
}

/*
** This function returns a pointer to a blob of memory associated with
** a single shared-btree. The memory is used by client code for it's own
** purposes (for example, to store a high-level schema associated with 
................................................................................
** Just before the shared-btree is closed, the function passed as the 
** xFree argument when the memory allocation was made is invoked on the 
** blob of allocated memory. This function should not call sqlite3_free()
** on the memory, the btree layer does that.
*/
void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
  BtShared *pBt = p->pBt;


  if( !pBt->pSchema ){
    pBt->pSchema = sqlite3MallocZero(nBytes);
    pBt->xFreeSchema = xFree;
  }
  return pBt->pSchema;
}

/*
** Return true if another user of the same shared btree as the argument
** handle holds an exclusive lock on the sqlite_master table.
*/
int sqlite3BtreeSchemaLocked(Btree *p){


  return (queryTableLock(p, MASTER_ROOT, READ_LOCK)!=SQLITE_OK);
}


#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Obtain a lock on the table whose root page is iTab.  The
** lock is a write lock if isWritelock is true or a read lock
** if it is false.
*/
int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
  int rc = SQLITE_OK;
  u8 lockType = (isWriteLock?WRITE_LOCK:READ_LOCK);

  rc = queryTableLock(p, iTab, lockType);
  if( rc==SQLITE_OK ){
    rc = lockTable(p, iTab, lockType);
  }

  return rc;
}
#endif

#ifndef SQLITE_OMIT_INCRBLOB
/*
** Argument pCsr must be a cursor opened for writing on an 
** INTKEY table currently pointing at a valid table entry. 
** This function modifies the data stored as part of that entry.
** Only the data content may only be modified, it is not possible
** to change the length of the data stored.
*/
int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){


  assert(pCsr->isIncrblobHandle);
  if( pCsr->eState==CURSOR_REQUIRESEEK ){
    return SQLITE_ABORT;
  }

  /* Check some preconditions: 
  **   (a) the cursor is open for writing,
................................................................................
**
** This function sets a flag only. The actual page location cache
** (stored in BtCursor.aOverflow[]) is allocated and used by function
** accessPayload() (the worker function for sqlite3BtreeData() and
** sqlite3BtreePutData()).
*/
void sqlite3BtreeCacheOverflow(BtCursor *pCur){


  assert(!pCur->isIncrblobHandle);
  assert(!pCur->aOverflow);
  pCur->isIncrblobHandle = 1;
}
#endif







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1508
....
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
....
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
....
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
....
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641

1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
....
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
....
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
....
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
....
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
....
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
....
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
....
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
....
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
....
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
....
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
....
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257

2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
....
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
....
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
....
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
....
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
....
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
....
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
....
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572

2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
....
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
....
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
....
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
....
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
....
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
....
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
....
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
....
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
....
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
....
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
....
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
....
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
....
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466

3467
3468
3469
3470
3471
3472
3473
3474
3475
....
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492

3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510

3511
3512
3513
3514
3515

3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534

3535
3536
3537
3538


3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
....
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
....
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
....
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
....
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
....
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
....
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
....
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
....
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
....
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
....
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
....
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
....
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
....
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
....
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
....
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
....
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
....
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
....
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
....
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
....
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
....
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
....
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
....
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
....
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
....
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
....
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
....
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
....
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
....
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
....
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
....
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970

5971
5972
5973
5974
5975
5976
5977



5978
5979



5980
5981
5982
5983
5984
5985
5986
....
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
....
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
....
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181

6182
6183
6184
6185

6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
....
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
....
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
....
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
....
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
....
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
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** 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 1.403 2007/08/20 22:48:42 drh 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"

/*
** The header string that appears at the beginning of every
** SQLite database.
*/
static const char zMagicHeader[] = SQLITE_FILE_HEADER;


/*
** Set this global variable to 1 to enable tracing using the TRACE
** macro.
*/
#if SQLITE_TEST
int sqlite3_btree_trace=0;  /* True to enable tracing */
#endif

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** A flag to indicate whether or not shared cache is enabled.  Also,
** a list of BtShared objects that are eligible for participation
** in shared cache.  The variables have file scope during normal builds,
** but the test harness needs to access these variables so make them
** global for test builds.
*/
#ifdef SQLITE_TEST
BtShared *sqlite3SharedCacheList = 0;
int sqlite3SharedCacheEnabled = 0;
#else
static BtShared *sqlite3SharedCacheList = 0;
static int sqlite3SharedCacheEnabled = 0;
#endif

#endif /* SQLITE_OMIT_SHARED_CACHE */

#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Enable or disable the shared pager and schema features.
**
** This routine has no effect on existing database connections.
................................................................................
** sqlite3_open(), sqlite3_open16(), or sqlite3_open_v2().
*/
int sqlite3_enable_shared_cache(int enable){
  sqlite3SharedCacheEnabled = enable;
  return SQLITE_OK;
}
#endif


/*
** Forward declaration
*/
static int checkReadLocks(Btree*,Pgno,BtCursor*);


................................................................................
** SQLITE_OK if the lock may be obtained (by calling lockTable()), or
** SQLITE_LOCKED if not.
*/
static int queryTableLock(Btree *p, Pgno iTab, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pIter;

  assert( sqlite3_mutex_held(pBt->mutex) );
  
  /* This is a no-op if the shared-cache is not enabled */
  if( !p->sharable ){
    return SQLITE_OK;
  }

  /* This (along with lockTable()) is where the ReadUncommitted flag is
  ** dealt with. If the caller is querying for a read-lock and the flag is
................................................................................
** SQLITE_OK is returned if the lock is added successfully. SQLITE_BUSY and
** SQLITE_NOMEM may also be returned.
*/
static int lockTable(Btree *p, Pgno iTable, u8 eLock){
  BtShared *pBt = p->pBt;
  BtLock *pLock = 0;
  BtLock *pIter;

  assert( sqlite3_mutex_held(pBt->mutex) );

  /* This is a no-op if the shared-cache is not enabled */
  if( !p->sharable ){
    return SQLITE_OK;
  }

  assert( SQLITE_OK==queryTableLock(p, iTable, eLock) );
................................................................................
/*
** Release all the table locks (locks obtained via calls to the lockTable()
** procedure) held by Btree handle p.
*/
static void unlockAllTables(Btree *p){
  BtLock **ppIter = &p->pBt->pLock;

  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( p->sharable || 0==*ppIter );

  while( *ppIter ){
    BtLock *pLock = *ppIter;
    if( pLock->pBtree==p ){
      *ppIter = pLock->pNext;
      sqlite3_free(pLock);
................................................................................

/*
** Invalidate the overflow page-list cache for all cursors opened
** on the shared btree structure pBt.
*/
static void invalidateAllOverflowCache(BtShared *pBt){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  for(p=pBt->pCursor; p; p=p->pNext){
    invalidateOverflowCache(p);
  }
}
#else
  #define invalidateOverflowCache(x)
  #define invalidateAllOverflowCache(x)
................................................................................
** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
*/
static int saveCursorPosition(BtCursor *pCur){
  int rc;

  assert( CURSOR_VALID==pCur->eState );
  assert( 0==pCur->pKey );
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );

  rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);

  /* If this is an intKey table, then the above call to BtreeKeySize()
  ** stores the integer key in pCur->nKey. In this case this value is
  ** all that is required. Otherwise, if pCur is not open on an intKey
  ** table, then malloc space for and store the pCur->nKey bytes of key 
................................................................................
/*
** Save the positions of all cursors except pExcept open on the table 
** with root-page iRoot. Usually, this is called just before cursor
** pExcept is used to modify the table (BtreeDelete() or BtreeInsert()).
*/
static int saveAllCursors(BtShared *pBt, Pgno iRoot, BtCursor *pExcept){
  BtCursor *p;
  assert( sqlite3_mutex_held(pBt->mutex) );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p!=pExcept && (0==iRoot || p->pgnoRoot==iRoot) && 
        p->eState==CURSOR_VALID ){
      int rc = saveCursorPosition(p);
      if( SQLITE_OK!=rc ){
        return rc;
      }
................................................................................
  return SQLITE_OK;
}

/*
** Clear the current cursor position.
*/
static void clearCursorPosition(BtCursor *pCur){
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  sqlite3_free(pCur->pKey);
  pCur->pKey = 0;
  pCur->eState = CURSOR_INVALID;
}

/*
** Restore the cursor to the position it was in (or as close to as possible)
................................................................................
#ifndef SQLITE_OMIT_AUTOVACUUM
/*
** Given a page number of a regular database page, return the page
** number for the pointer-map page that contains the entry for the
** input page number.
*/
static Pgno ptrmapPageno(BtShared *pBt, Pgno pgno){
  int nPagesPerMapPage, iPtrMap, ret;
  assert( sqlite3_mutex_held(pBt->mutex) );
  nPagesPerMapPage = (pBt->usableSize/5)+1;
  iPtrMap = (pgno-2)/nPagesPerMapPage;
  ret = (iPtrMap*nPagesPerMapPage) + 2; 
  if( ret==PENDING_BYTE_PAGE(pBt) ){
    ret++;
  }
  return ret;
}

/*
................................................................................
static int ptrmapPut(BtShared *pBt, Pgno key, u8 eType, Pgno parent){
  DbPage *pDbPage;  /* The pointer map page */
  u8 *pPtrmap;      /* The pointer map data */
  Pgno iPtrmap;     /* The pointer map page number */
  int offset;       /* Offset in pointer map page */
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );
  /* The master-journal page number must never be used as a pointer map page */
  assert( 0==PTRMAP_ISPAGE(pBt, PENDING_BYTE_PAGE(pBt)) );

  assert( pBt->autoVacuum );
  if( key==0 ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
*/
static int ptrmapGet(BtShared *pBt, Pgno key, u8 *pEType, Pgno *pPgno){
  DbPage *pDbPage;   /* The pointer map page */
  int iPtrmap;       /* Pointer map page index */
  u8 *pPtrmap;       /* Pointer map page data */
  int offset;        /* Offset of entry in pointer map */
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );

  iPtrmap = PTRMAP_PAGENO(pBt, key);
  rc = sqlite3PagerGet(pBt->pPager, iPtrmap, &pDbPage);
  if( rc!=0 ){
    return rc;
  }
  pPtrmap = (u8 *)sqlite3PagerGetData(pDbPage);
................................................................................

/*
** This a more complex version of sqlite3BtreeFindCell() that works for
** pages that do contain overflow cells.  See insert
*/
static u8 *findOverflowCell(MemPage *pPage, int iCell){
  int i;
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  for(i=pPage->nOverflow-1; i>=0; i--){
    int k;
    struct _OvflCell *pOvfl;
    pOvfl = &pPage->aOvfl[i];
    k = pOvfl->idx;
    if( k<=iCell ){
      if( k==iCell ){
................................................................................
void sqlite3BtreeParseCellPtr(
  MemPage *pPage,         /* Page containing the cell */
  u8 *pCell,              /* Pointer to the cell text. */
  CellInfo *pInfo         /* Fill in this structure */
){
  int n;                  /* Number bytes in cell content header */
  u32 nPayload;           /* Number of bytes of cell payload */

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  pInfo->pCell = pCell;
  assert( pPage->leaf==0 || pPage->leaf==1 );
  n = pPage->childPtrSize;
  assert( n==4-4*pPage->leaf );
  if( pPage->hasData ){
    n += getVarint32(&pCell[n], &nPayload);
................................................................................
/*
** If the cell with index iCell on page pPage contains a pointer
** to an overflow page, insert an entry into the pointer-map
** for the overflow page.
*/
static int ptrmapPutOvfl(MemPage *pPage, int iCell){
  u8 *pCell;
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pCell = findOverflowCell(pPage, iCell);
  return ptrmapPutOvflPtr(pPage, pCell);
}
#endif


/*
................................................................................
  unsigned char *data;       /* The page data */
  unsigned char *temp;       /* Temp area for cell content */

  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( pPage->pBt!=0 );
  assert( pPage->pBt->usableSize <= SQLITE_MAX_PAGE_SIZE );
  assert( pPage->nOverflow==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  temp = sqlite3_malloc( pPage->pBt->pageSize );
  if( temp==0 ) return SQLITE_NOMEM;
  data = pPage->aData;
  hdr = pPage->hdrOffset;
  cellOffset = pPage->cellOffset;
  nCell = pPage->nCell;
  assert( nCell==get2byte(&data[hdr+3]) );
................................................................................
  int nCell;
  int cellOffset;
  unsigned char *data;
  
  data = pPage->aData;
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( pPage->pBt );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( nByte<4 ) nByte = 4;
  if( pPage->nFree<nByte || pPage->nOverflow>0 ) return 0;
  pPage->nFree -= nByte;
  hdr = pPage->hdrOffset;

  nFrag = data[hdr+7];
  if( nFrag<60 ){
................................................................................
  int addr, pbegin, hdr;
  unsigned char *data = pPage->aData;

  assert( pPage->pBt!=0 );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( start>=pPage->hdrOffset+6+(pPage->leaf?0:4) );
  assert( (start + size)<=pPage->pBt->usableSize );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( size<4 ) size = 4;

#ifdef SQLITE_SECURE_DELETE
  /* Overwrite deleted information with zeros when the SECURE_DELETE 
  ** option is enabled at compile-time */
  memset(&data[start], 0, size);
#endif
................................................................................
** Decode the flags byte (the first byte of the header) for a page
** and initialize fields of the MemPage structure accordingly.
*/
static void decodeFlags(MemPage *pPage, int flagByte){
  BtShared *pBt;     /* A copy of pPage->pBt */

  assert( pPage->hdrOffset==(pPage->pgno==1 ? 100 : 0) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pPage->intKey = (flagByte & (PTF_INTKEY|PTF_LEAFDATA))!=0;
  pPage->zeroData = (flagByte & PTF_ZERODATA)!=0;
  pPage->leaf = (flagByte & PTF_LEAF)!=0;
  pPage->childPtrSize = 4*(pPage->leaf==0);
  pBt = pPage->pBt;
  if( flagByte & PTF_LEAFDATA ){
    pPage->leafData = 1;
................................................................................
  int cellOffset;    /* Offset from start of page to first cell pointer */
  int nFree;         /* Number of unused bytes on the page */
  int top;           /* First byte of the cell content area */

  pBt = pPage->pBt;
  assert( pBt!=0 );
  assert( pParent==0 || pParent->pBt==pBt );
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pPage->pgno==sqlite3PagerPagenumber(pPage->pDbPage) );
  assert( pPage->aData == &((unsigned char*)pPage)[-pBt->pageSize] );
  if( pPage->pParent!=pParent && (pPage->pParent!=0 || pPage->isInit) ){
    /* The parent page should never change unless the file is corrupt */
    return SQLITE_CORRUPT_BKPT;
  }
  if( pPage->isInit ) return SQLITE_OK;
................................................................................
  BtShared *pBt = pPage->pBt;
  int hdr = pPage->hdrOffset;
  int first;

  assert( sqlite3PagerPagenumber(pPage->pDbPage)==pPage->pgno );
  assert( &data[pBt->pageSize] == (unsigned char*)pPage );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( sqlite3_mutex_held(pBt->mutex) );
  memset(&data[hdr], 0, pBt->usableSize - hdr);
  data[hdr] = flags;
  first = hdr + 8 + 4*((flags&PTF_LEAF)==0);
  memset(&data[hdr+1], 0, 4);
  data[hdr+7] = 0;
  put2byte(&data[hdr+5], pBt->usableSize);
  pPage->nFree = pBt->usableSize - first;
................................................................................
  MemPage **ppPage,    /* Return the page in this parameter */
  int noContent        /* Do not load page content if true */
){
  int rc;
  MemPage *pPage;
  DbPage *pDbPage;

  assert( sqlite3_mutex_held(pBt->mutex) );
  rc = sqlite3PagerAcquire(pBt->pPager, pgno, (DbPage**)&pDbPage, noContent);
  if( rc ) return rc;
  pPage = (MemPage *)sqlite3PagerGetExtra(pDbPage);
  pPage->aData = sqlite3PagerGetData(pDbPage);
  pPage->pDbPage = pDbPage;
  pPage->pBt = pBt;
  pPage->pgno = pgno;
................................................................................
static int getAndInitPage(
  BtShared *pBt,          /* The database file */
  Pgno pgno,           /* Number of the page to get */
  MemPage **ppPage,    /* Write the page pointer here */
  MemPage *pParent     /* Parent of the page */
){
  int rc;
  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno==0 ){
    return SQLITE_CORRUPT_BKPT; 
  }
  rc = sqlite3BtreeGetPage(pBt, pgno, ppPage, 0);
  if( rc==SQLITE_OK && (*ppPage)->isInit==0 ){
    rc = sqlite3BtreeInitPage(*ppPage, pParent);
  }
................................................................................
** call to sqlite3BtreeGetPage.
*/
static void releasePage(MemPage *pPage){
  if( pPage ){
    assert( pPage->aData );
    assert( pPage->pBt );
    assert( &pPage->aData[pPage->pBt->pageSize]==(unsigned char*)pPage );
    assert( sqlite3_mutex_held(pPage->pBt->mutex) );
    sqlite3PagerUnref(pPage->pDbPage);
  }
}

/*
** This routine is called when the reference count for a page
** reaches zero.  We need to unref the pParent pointer when that
** happens.
*/
static void pageDestructor(DbPage *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage *)sqlite3PagerGetExtra(pData);
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( pPage->pParent ){
    MemPage *pParent = pPage->pParent;
    pPage->pParent = 0;
    releasePage(pParent);
  }
  pPage->isInit = 0;
}
................................................................................
** This routine needs to reset the extra data section at the end of the
** page to agree with the restored data.
*/
static void pageReinit(DbPage *pData, int pageSize){
  MemPage *pPage;
  assert( (pageSize & 7)==0 );
  pPage = (MemPage *)sqlite3PagerGetExtra(pData);
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( pPage->isInit ){
    pPage->isInit = 0;
    sqlite3BtreeInitPage(pPage, pPage->pParent);
  }
}

/*
................................................................................
*/
int sqlite3BtreeOpen(
  const char *zFilename,  /* Name of the file containing the BTree database */
  sqlite3 *pSqlite,       /* Associated database handle */
  Btree **ppBtree,        /* Pointer to new Btree object written here */
  int flags               /* Options */
){
  sqlite3_vfs *pVfs;      /* The VFS to use for this btree */
  BtShared *pBt = 0;      /* Shared part of btree structure */
  Btree *p;               /* Handle to return */
  int rc = SQLITE_OK;
  int nReserve;
  unsigned char zDbHeader[100];

  if( pSqlite ){
    pVfs = pSqlite->pVfs;
  }else{
    pVfs = sqlite3_vfs_find(0);
  }
  assert( pSqlite==0 || sqlite3_mutex_held(pSqlite->mutex) );

  /* Set the variable isMemdb to true for an in-memory database, or 
  ** false for a file-based database. This symbol is only required if
  ** either of the shared-data or autovacuum features are compiled 
  ** into the library.
  */
#if !defined(SQLITE_OMIT_SHARED_CACHE) || !defined(SQLITE_OMIT_AUTOVACUUM)
  #ifdef SQLITE_OMIT_MEMORYDB
................................................................................
*/
static int removeFromSharingList(BtShared *pBt){
#ifndef SQLITE_OMIT_SHARED_CACHE
  sqlite3_mutex *pMaster;
  BtShared *pList;
  int removed = 0;

  assert( sqlite3_mutex_notheld(pBt->mutex) );
  pMaster = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(pMaster);
  pBt->nRef--;
  if( pBt->nRef<=0 ){
    if( sqlite3SharedCacheList==pBt ){
      sqlite3SharedCacheList = pBt->pNext;
    }else{
................................................................................
  }
#endif

  sqlite3_free(p);
  return SQLITE_OK;
}

#if SQLITE_THREADSAFE && !defined(SQLITE_OMIT_SHARED_CACHE)
/*
** 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.
................................................................................
  assert( p->pNext==0 || p->pNext->pSqlite==p->pSqlite );
  assert( p->pPrev==0 || p->pPrev->pSqlite==p->pSqlite );
  assert( p->sharable || (p->pNext==0 && p->pPrev==0) );

  /* Check for locking consistency */
  assert( !p->locked || p->wantToLock>0 );
  assert( p->sharable || p->wantToLock==0 );

  /* We should already hold a lock on the database connection */
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );

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

  /* In most cases, we should be able to acquire the lock we
  ** want without having to go throught the ascending lock
................................................................................
  }
}
#endif /* !SQLITE_OMIT_SHARED_CACHE */

/*
** Exit the recursive mutex on a Btree.
*/
#if SQLITE_THREADSAFE && !defined(SQLITE_OMIT_SHARED_CACHE)
void sqlite3BtreeLeave(Btree *p){
  if( p->sharable ){
    assert( p->wantToLock>0 );
    p->wantToLock--;
    if( p->wantToLock==0 ){
      assert( p->locked );
      sqlite3_mutex_leave(p->pBt->mutex);
      p->locked = 0;
    }
  }
}
#endif


#if SQLITE_THREADSAFE && !defined(SQLITE_OMIT_SHARED_CACHE)
/*
** Short-cuts for entering and leaving mutexes on a cursor.
*/
static void cursorLeave(BtCursor *p){
  sqlite3BtreeLeave(p->pBt);
}
static void cursorEnter(BtCursor *pCur){
  sqlite3BtreeEnter(pCur->pBt);
}
#else
# define cursorEnter(X)
# define cursorLeave(X)
#endif /* !SQLITE_OMIT_SHARED_CACHE */

/*
** Change the busy handler callback function.
*/
int sqlite3BtreeSetBusyHandler(Btree *p, BusyHandler *pHandler){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  pBt->pBusyHandler = pHandler;
  sqlite3PagerSetBusyhandler(pBt->pPager, pHandler);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Change the limit on the number of pages allowed in the cache.
**
** The maximum number of cache pages is set to the absolute
................................................................................
** an abrupt power failure when synchronous is off, the database
** could be left in an inconsistent and unrecoverable state.
** Synchronous is on by default so database corruption is not
** normally a worry.
*/
int sqlite3BtreeSetCacheSize(Btree *p, int mxPage){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  sqlite3PagerSetCachesize(pBt->pPager, mxPage);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Change the way data is synced to disk in order to increase or decrease
** how well the database resists damage due to OS crashes and power
** failures.  Level 1 is the same as asynchronous (no syncs() occur and
................................................................................
** there is a high probability of damage)  Level 2 is the default.  There
** is a very low but non-zero probability of damage.  Level 3 reduces the
** probability of damage to near zero but with a write performance reduction.
*/
#ifndef SQLITE_OMIT_PAGER_PRAGMAS
int sqlite3BtreeSetSafetyLevel(Btree *p, int level, int fullSync){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  sqlite3PagerSetSafetyLevel(pBt->pPager, level, fullSync);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}
#endif

/*
** Return TRUE if the given btree is set to safety level 1.  In other
** words, return TRUE if no sync() occurs on the disk files.
*/
int sqlite3BtreeSyncDisabled(Btree *p){
  BtShared *pBt = p->pBt;
  int rc;
  assert( pBt && pBt->pPager );
  sqlite3BtreeEnter(p);
  rc = sqlite3PagerNosync(pBt->pPager);
  sqlite3BtreeLeave(p);
  return rc;
}

#if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
/*
** Change the default pages size and the number of reserved bytes per page.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
................................................................................
** at the beginning of a page.
**
** If parameter nReserve is less than zero, then the number of reserved
** bytes per page is left unchanged.
*/
int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( pBt->pageSizeFixed ){
    sqlite3BtreeLeave(p);
    return SQLITE_READONLY;
  }
  if( nReserve<0 ){
    nReserve = pBt->pageSize - pBt->usableSize;
  }
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    assert( (pageSize & 7)==0 );
    assert( !pBt->pPage1 && !pBt->pCursor );
    pBt->pageSize = sqlite3PagerSetPagesize(pBt->pPager, pageSize);
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Return the currently defined page size
*/
int sqlite3BtreeGetPageSize(Btree *p){
  return p->pBt->pageSize;
}
int sqlite3BtreeGetReserve(Btree *p){
  int n;
  sqlite3BtreeEnter(p);
  n = p->pBt->pageSize - p->pBt->usableSize;
  sqlite3BtreeLeave(p);
  return n;
}

/*
** Set the maximum page count for a database if mxPage is positive.
** No changes are made if mxPage is 0 or negative.
** Regardless of the value of mxPage, return the maximum page count.
*/
int sqlite3BtreeMaxPageCount(Btree *p, int mxPage){
  int n;
  sqlite3BtreeEnter(p);
  n = sqlite3PagerMaxPageCount(p->pBt->pPager, mxPage);
  sqlite3BtreeLeave(p);
  return n;
}
#endif /* !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM) */

/*
** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
** is disabled. The default value for the auto-vacuum property is 
................................................................................
** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
*/
int sqlite3BtreeSetAutoVacuum(Btree *p, int autoVacuum){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return SQLITE_READONLY;
#else
  BtShared *pBt = p->pBt;
  int rc = SQLITE_OK;
  int av = (autoVacuum?1:0);

  sqlite3BtreeEnter(p);
  if( pBt->pageSizeFixed && av!=pBt->autoVacuum ){
    rc = SQLITE_READONLY;

  }else{
    pBt->autoVacuum = av;
  }
  sqlite3BtreeLeave(p);
  return rc;
#endif
}

/*
** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
** enabled 1 is returned. Otherwise 0.
*/
int sqlite3BtreeGetAutoVacuum(Btree *p){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return BTREE_AUTOVACUUM_NONE;
#else
  int rc;
  sqlite3BtreeEnter(p);
  rc = (
    (!p->pBt->autoVacuum)?BTREE_AUTOVACUUM_NONE:
    (!p->pBt->incrVacuum)?BTREE_AUTOVACUUM_FULL:
    BTREE_AUTOVACUUM_INCR
  );
  sqlite3BtreeLeave(p);
  return rc;
#endif
}


/*
** Get a reference to pPage1 of the database file.  This will
** also acquire a readlock on that file.
................................................................................
** well-formed database file, then SQLITE_CORRUPT is returned.
** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
** is returned if we run out of memory. 
*/
static int lockBtree(BtShared *pBt){
  int rc, pageSize;
  MemPage *pPage1;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pBt->pPage1 ) return SQLITE_OK;
  rc = sqlite3BtreeGetPage(pBt, 1, &pPage1, 0);
  if( rc!=SQLITE_OK ) return rc;
  

  /* Do some checking to help insure the file we opened really is
  ** a valid database file. 
................................................................................

/*
** This routine works like lockBtree() except that it also invokes the
** busy callback if there is lock contention.
*/
static int lockBtreeWithRetry(Btree *pRef){
  int rc = SQLITE_OK;

  assert( sqlite3_mutex_held(pRef->pSqlite->mutex) );
  assert( sqlite3_mutex_held(pRef->pBt->mutex) );
  if( pRef->inTrans==TRANS_NONE ){
    u8 inTransaction = pRef->pBt->inTransaction;
    btreeIntegrity(pRef);
    rc = sqlite3BtreeBeginTrans(pRef, 0);
    pRef->pBt->inTransaction = inTransaction;
    pRef->inTrans = TRANS_NONE;
    if( rc==SQLITE_OK ){
................................................................................
** has the effect of releasing the read lock.
**
** If there are any outstanding cursors, this routine is a no-op.
**
** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(BtShared *pBt){
  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pBt->inTransaction==TRANS_NONE && pBt->pCursor==0 && pBt->pPage1!=0 ){
    if( sqlite3PagerRefcount(pBt->pPager)>=1 ){
      if( pBt->pPage1->aData==0 ){
        MemPage *pPage = pBt->pPage1;
        pPage->aData = &((u8*)pPage)[-pBt->pageSize];
        pPage->pBt = pBt;
        pPage->pgno = 1;
................................................................................
** Create a new database by initializing the first page of the
** file.
*/
static int newDatabase(BtShared *pBt){
  MemPage *pP1;
  unsigned char *data;
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( sqlite3PagerPagecount(pBt->pPager)>0 ) return SQLITE_OK;
  pP1 = pBt->pPage1;
  assert( pP1!=0 );
  data = pP1->aData;
  rc = sqlite3PagerWrite(pP1->pDbPage);
  if( rc ) return rc;
  memcpy(data, zMagicHeader, sizeof(zMagicHeader));
................................................................................
** when A already has a read lock, we encourage A to give up and let B
** proceed.
*/
int sqlite3BtreeBeginTrans(Btree *p, int wrflag){
  BtShared *pBt = p->pBt;
  int rc = SQLITE_OK;

  sqlite3BtreeEnter(p);
  btreeIntegrity(p);

  /* If the btree is already in a write-transaction, or it
  ** is already in a read-transaction and a read-transaction
  ** is requested, this is a no-op.
  */
  if( p->inTrans==TRANS_WRITE || (p->inTrans==TRANS_READ && !wrflag) ){
    goto trans_begun;
  }

  /* Write transactions are not possible on a read-only database */
  if( pBt->readOnly && wrflag ){
    rc = SQLITE_READONLY;
    goto trans_begun;
  }

  /* If another database handle has already opened a write transaction 
  ** on this shared-btree structure and a second write transaction is
  ** requested, return SQLITE_BUSY.
  */
  if( pBt->inTransaction==TRANS_WRITE && wrflag ){
    rc = SQLITE_BUSY;
    goto trans_begun;
  }

  do {
    if( pBt->pPage1==0 ){
      rc = lockBtree(pBt);
    }

................................................................................
    }
    p->inTrans = (wrflag?TRANS_WRITE:TRANS_READ);
    if( p->inTrans>pBt->inTransaction ){
      pBt->inTransaction = p->inTrans;
    }
  }


trans_begun:
  btreeIntegrity(p);
  sqlite3BtreeLeave(p);
  return rc;
}

#ifndef SQLITE_OMIT_AUTOVACUUM

/*
** Set the pointer-map entries for all children of page pPage. Also, if
................................................................................
  int i;                             /* Counter variable */
  int nCell;                         /* Number of cells in page pPage */
  int rc;                            /* Return code */
  BtShared *pBt = pPage->pBt;
  int isInitOrig = pPage->isInit;
  Pgno pgno = pPage->pgno;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  rc = sqlite3BtreeInitPage(pPage, pPage->pParent);
  if( rc!=SQLITE_OK ){
    goto set_child_ptrmaps_out;
  }
  nCell = pPage->nCell;

  for(i=0; i<nCell; i++){
................................................................................
** PTRMAP_OVERFLOW1: pPage is a btree-page. The pointer points at an overflow
**                   page pointed to by one of the cells on pPage.
**
** PTRMAP_OVERFLOW2: pPage is an overflow-page. The pointer points at the next
**                   overflow page in the list.
*/
static int modifyPagePointer(MemPage *pPage, Pgno iFrom, Pgno iTo, u8 eType){
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( eType==PTRMAP_OVERFLOW2 ){
    /* The pointer is always the first 4 bytes of the page in this case.  */
    if( get4byte(pPage->aData)!=iFrom ){
      return SQLITE_CORRUPT_BKPT;
    }
    put4byte(pPage->aData, iTo);
  }else{
................................................................................
  MemPage *pPtrPage;   /* The page that contains a pointer to pDbPage */
  Pgno iDbPage = pDbPage->pgno;
  Pager *pPager = pBt->pPager;
  int rc;

  assert( eType==PTRMAP_OVERFLOW2 || eType==PTRMAP_OVERFLOW1 || 
      eType==PTRMAP_BTREE || eType==PTRMAP_ROOTPAGE );
  assert( sqlite3_mutex_held(pBt->mutex) );

  /* Move page iDbPage from it's current location to page number iFreePage */
  TRACE(("AUTOVACUUM: Moving %d to free page %d (ptr page %d type %d)\n", 
      iDbPage, iFreePage, iPtrPage, eType));
  rc = sqlite3PagerMovepage(pPager, pDbPage->pDbPage, iFreePage);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................
** number of pages the database file will contain after this 
** process is complete.
*/
static int incrVacuumStep(BtShared *pBt, Pgno nFin){
  Pgno iLastPg;             /* Last page in the database */
  Pgno nFreeList;           /* Number of pages still on the free-list */

  assert( sqlite3_mutex_held(pBt->mutex) );
  iLastPg = pBt->nTrunc;
  if( iLastPg==0 ){
    iLastPg = sqlite3PagerPagecount(pBt->pPager);
  }

  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){
    int rc;
................................................................................
** It performs a single unit of work towards an incremental vacuum.
**
** If the incremental vacuum is finished after this function has run,
** SQLITE_DONE is returned. If it is not finished, but no error occured,
** SQLITE_OK is returned. Otherwise an SQLite error code. 
*/
int sqlite3BtreeIncrVacuum(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);
  assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
  if( !pBt->autoVacuum ){
    rc = SQLITE_DONE;

  }else{
    invalidateAllOverflowCache(pBt);
    rc = incrVacuumStep(pBt, 0);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** This routine is called prior to sqlite3PagerCommit when a transaction
** is commited for an auto-vacuum database.
**
** If SQLITE_OK is returned, then *pnTrunc is set to the number of pages
................................................................................
static int autoVacuumCommit(BtShared *pBt, Pgno *pnTrunc){
  int rc = SQLITE_OK;
  Pager *pPager = pBt->pPager;
#ifndef NDEBUG
  int nRef = sqlite3PagerRefcount(pPager);
#endif

  assert( sqlite3_mutex_held(pBt->mutex) );
  invalidateAllOverflowCache(pBt);
  assert(pBt->autoVacuum);
  if( !pBt->incrVacuum ){
    Pgno nFin = 0;

    if( pBt->nTrunc==0 ){
      Pgno nFree;
................................................................................
** the write-transaction for this database file is to delete the journal.
*/
int sqlite3BtreeCommitPhaseOne(Btree *p, const char *zMaster){
  int rc = SQLITE_OK;
  if( p->inTrans==TRANS_WRITE ){
    BtShared *pBt = p->pBt;
    Pgno nTrunc = 0;
    sqlite3BtreeEnter(p);
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum ){
      rc = autoVacuumCommit(pBt, &nTrunc); 
      if( rc!=SQLITE_OK ){
        sqlite3BtreeLeave(p);
        return rc;
      }
    }
#endif
    rc = sqlite3PagerCommitPhaseOne(pBt->pPager, zMaster, nTrunc);
    sqlite3BtreeLeave(p);
  }
  return rc;
}

/*
** Commit the transaction currently in progress.
**
................................................................................
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeCommitPhaseTwo(Btree *p){
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);
  btreeIntegrity(p);

  /* If the handle has a write-transaction open, commit the shared-btrees 
  ** transaction and set the shared state to TRANS_READ.
  */
  if( p->inTrans==TRANS_WRITE ){
    int rc;
    assert( pBt->inTransaction==TRANS_WRITE );
    assert( pBt->nTransaction>0 );
    rc = sqlite3PagerCommitPhaseTwo(pBt->pPager);
    if( rc!=SQLITE_OK ){
      sqlite3BtreeLeave(p);
      return rc;
    }
    pBt->inTransaction = TRANS_READ;
    pBt->inStmt = 0;
  }
  unlockAllTables(p);

................................................................................
  /* Set the handles current transaction state to TRANS_NONE and unlock
  ** the pager if this call closed the only read or write transaction.
  */
  p->inTrans = TRANS_NONE;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);
  sqlite3BtreeLeave(p);
  return SQLITE_OK;
}

/*
** Do both phases of a commit.
*/
int sqlite3BtreeCommit(Btree *p){
  int rc;
  sqlite3BtreeEnter(p);
  rc = sqlite3BtreeCommitPhaseOne(p, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3BtreeCommitPhaseTwo(p);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

#ifndef NDEBUG
/*
** Return the number of write-cursors open on this handle. This is for use
** in assert() expressions, so it is only compiled if NDEBUG is not
................................................................................
** are no active cursors, it also releases the read lock.
*/
int sqlite3BtreeRollback(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  MemPage *pPage1;

  sqlite3BtreeEnter(p);
  rc = saveAllCursors(pBt, 0, 0);
#ifndef SQLITE_OMIT_SHARED_CACHE
  if( rc!=SQLITE_OK ){
    /* This is a horrible situation. An IO or malloc() error occured whilst
    ** trying to save cursor positions. If this is an automatic rollback (as
    ** the result of a constraint, malloc() failure or IO error) then 
    ** the cache may be internally inconsistent (not contain valid trees) so
................................................................................
  }

  p->inTrans = TRANS_NONE;
  pBt->inStmt = 0;
  unlockBtreeIfUnused(pBt);

  btreeIntegrity(p);
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Start a statement subtransaction.  The subtransaction can
** can be rolled back independently of the main transaction.
** You must start a transaction before starting a subtransaction.
................................................................................
** that are contained within a BEGIN...COMMIT block.  If a constraint
** error occurs within the statement, the effect of that one statement
** can be rolled back without having to rollback the entire transaction.
*/
int sqlite3BtreeBeginStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( (p->inTrans!=TRANS_WRITE) || pBt->inStmt ){
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;

  }else{
    assert( pBt->inTransaction==TRANS_WRITE );
    rc = pBt->readOnly ? SQLITE_OK : sqlite3PagerStmtBegin(pBt->pPager);
    pBt->inStmt = 1;
  }
  sqlite3BtreeLeave(p);
  return rc;
}


/*
** Commit the statment subtransaction currently in progress.  If no
** subtransaction is active, this is a no-op.
*/
int sqlite3BtreeCommitStmt(Btree *p){
  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3PagerStmtCommit(pBt->pPager);
  }else{
    rc = SQLITE_OK;
  }
  pBt->inStmt = 0;
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Rollback the active statement subtransaction.  If no subtransaction
** is active this routine is a no-op.
**
................................................................................
** All cursors will be invalidated by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqlite3BtreeRollbackStmt(Btree *p){
  int rc = SQLITE_OK;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  sqlite3MallocDisallow();
  if( pBt->inStmt && !pBt->readOnly ){
    rc = sqlite3PagerStmtRollback(pBt->pPager);
    assert( countWriteCursors(pBt)==0 );
    pBt->inStmt = 0;
  }
  sqlite3MallocAllow();
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Default key comparison function to be used if no comparison function
** is specified on the sqlite3BtreeCursor() call.
*/
................................................................................
**
** The comparison function must be logically the same for every cursor
** on a particular table.  Changing the comparison function will result
** in incorrect operations.  If the comparison function is NULL, a
** default comparison function is used.  The comparison function is
** always ignored for INTKEY tables.
*/
static int btreeCursor(
  Btree *p,                                   /* The btree */
  int iTable,                                 /* Root page of table to open */
  int wrFlag,                                 /* 1 to write. 0 read-only */
  int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
  void *pArg,                                 /* First arg to xCompare() */
  BtCursor **ppCur                            /* Write new cursor here */
){
  int rc;
  BtCursor *pCur;
  BtShared *pBt = p->pBt;

  assert( sqlite3_mutex_held(pBt->mutex) );
  *ppCur = 0;
  if( wrFlag ){
    if( pBt->readOnly ){
      return SQLITE_READONLY;
    }
    if( checkReadLocks(p, iTable, 0) ){
      return SQLITE_LOCKED;
................................................................................
    pCur->pNext->pPrev = pCur;
  }
  pBt->pCursor = pCur;
  pCur->eState = CURSOR_INVALID;
  *ppCur = pCur;

  return SQLITE_OK;

create_cursor_exception:
  if( pCur ){
    releasePage(pCur->pPage);
    sqlite3_free(pCur);
  }
  unlockBtreeIfUnused(pBt);
  return rc;
}
int sqlite3BtreeCursor(
  Btree *p,                                   /* The btree */
  int iTable,                                 /* Root page of table to open */
  int wrFlag,                                 /* 1 to write. 0 read-only */
  int (*xCmp)(void*,int,const void*,int,const void*), /* Key Comparison func */
  void *pArg,                                 /* First arg to xCompare() */
  BtCursor **ppCur                            /* Write new cursor here */
){
  int rc;
  sqlite3BtreeEnter(p);
  rc = btreeCursor(p, iTable, wrFlag, xCmp, pArg, ppCur);
  sqlite3BtreeLeave(p);
  return rc;
}


/*
** Close a cursor.  The read lock on the database file is released
** when the last cursor is closed.
*/
int sqlite3BtreeCloseCursor(BtCursor *pCur){
  BtShared *pBt = pCur->pBtree->pBt;

  cursorEnter(pCur);
  clearCursorPosition(pCur);
  if( pCur->pPrev ){
    pCur->pPrev->pNext = pCur->pNext;
  }else{
    pBt->pCursor = pCur->pNext;
  }
  if( pCur->pNext ){
    pCur->pNext->pPrev = pCur->pPrev;
  }
  releasePage(pCur->pPage);
  unlockBtreeIfUnused(pBt);
  invalidateOverflowCache(pCur);
  cursorLeave(pCur);
  sqlite3_free(pCur);
  return SQLITE_OK;
}

/*
** Make a temporary cursor by filling in the fields of pTempCur.
** The temporary cursor is not on the cursor list for the Btree.
*/
void sqlite3BtreeGetTempCursor(BtCursor *pCur, BtCursor *pTempCur){
  memcpy(pTempCur, pCur, sizeof(*pCur));
  pTempCur->pNext = 0;
  pTempCur->pPrev = 0;
  if( pTempCur->pPage ){
    cursorEnter(pCur);
    sqlite3PagerRef(pTempCur->pPage->pDbPage);
    cursorLeave(pCur);
  }
}

/*
** Delete a temporary cursor such as was made by the CreateTemporaryCursor()
** function above.
*/
void sqlite3BtreeReleaseTempCursor(BtCursor *pCur){
  if( pCur->pPage ){
    cursorEnter(pCur);
    sqlite3PagerUnref(pCur->pPage->pDbPage);
    cursorLeave(pCur);
  }
}

/*
** Make sure the BtCursor* given in the argument has a valid
** BtCursor.info structure.  If it is not already valid, call
** sqlite3BtreeParseCell() to fill it in.
................................................................................
** the key for the current entry.  If the cursor is not pointing
** to a valid entry, *pSize is set to 0. 
**
** For a table with the INTKEY flag set, this routine returns the key
** itself, not the number of bytes in the key.
*/
int sqlite3BtreeKeySize(BtCursor *pCur, i64 *pSize){
  int rc;

  sqlite3BtreeEnter(pCur->pBtree);
  rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nKey;
    }
  }
  sqlite3BtreeLeave(pCur->pBtree);
  return rc;
}

/*
** 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 sqlite3BtreeDataSize(BtCursor *pCur, u32 *pSize){
  int rc;

  sqlite3BtreeEnter(pCur->pBtree);
  rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_INVALID || pCur->eState==CURSOR_VALID );
    if( pCur->eState==CURSOR_INVALID ){
      /* Not pointing at a valid entry - set *pSize to 0. */
      *pSize = 0;
    }else{
      getCellInfo(pCur);
      *pSize = pCur->info.nData;
    }
  }
  sqlite3BtreeLeave(pCur->pBtree);
  return rc;
}

/*
** Given the page number of an overflow page in the database (parameter
** ovfl), this function finds the page number of the next page in the 
** linked list of overflow pages. If possible, it uses the auto-vacuum
................................................................................
  Pgno ovfl,                   /* Overflow page */
  MemPage **ppPage,            /* OUT: MemPage handle */
  Pgno *pPgnoNext              /* OUT: Next overflow page number */
){
  Pgno next = 0;
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );
  /* One of these must not be NULL. Otherwise, why call this function? */
  assert(ppPage || pPgnoNext);

  /* If pPgnoNext is NULL, then this function is being called to obtain
  ** a MemPage* reference only. No page-data is required in this case.
  */
  if( !pPgnoNext ){
................................................................................
  MemPage *pPage = pCur->pPage;        /* Btree page of current cursor entry */
  BtShared *pBt = pCur->pBtree->pBt;   /* Btree this cursor belongs to */

  assert( pPage );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  assert( offset>=0 );
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );

  getCellInfo(pCur);
  aPayload = pCur->info.pCell + pCur->info.nHeader;
  nKey = (pPage->intKey ? 0 : pCur->info.nKey);

  if( skipKey ){
    offset += nKey;
................................................................................
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeKey(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
  int rc;

  sqlite3BtreeEnter(pCur->pBtree);
  rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    if( pCur->pPage->intKey ){
      sqlite3BtreeLeave(pCur->pBtree);
      return SQLITE_CORRUPT_BKPT;
    }
    assert( pCur->pPage->intKey==0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = accessPayload(pCur, offset, amt, (unsigned char*)pBuf, 0, 0);
  }
  sqlite3BtreeLeave(pCur->pBtree);
  return rc;
}

/*
** Read part of the data associated with cursor pCur.  Exactly
** "amt" bytes will be transfered into pBuf[].  The transfer
** begins at "offset".
**
** Return SQLITE_OK on success or an error code if anything goes
** wrong.  An error is returned if "offset+amt" is larger than
** the available payload.
*/
int sqlite3BtreeData(BtCursor *pCur, u32 offset, u32 amt, void *pBuf){
  int rc;

  sqlite3BtreeEnter(pCur->pBtree);
  rc = restoreOrClearCursorPosition(pCur);
  if( rc==SQLITE_OK ){
    assert( pCur->eState==CURSOR_VALID );
    assert( pCur->pPage!=0 );
    assert( pCur->idx>=0 && pCur->idx<pCur->pPage->nCell );
    rc = accessPayload(pCur, offset, amt, pBuf, 1, 0);
  }
  sqlite3BtreeLeave(pCur->pBtree);
  return rc;
}

/*
** Return a pointer to payload information from the entry that the 
** pCur cursor is pointing to.  The pointer is to the beginning of
** the key if skipKey==0 and it points to the beginning of data if
................................................................................
  unsigned char *aPayload;
  MemPage *pPage;
  u32 nKey;
  int nLocal;

  assert( pCur!=0 && pCur->pPage!=0 );
  assert( pCur->eState==CURSOR_VALID );
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  pPage = pCur->pPage;
  assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
  getCellInfo(pCur);
  aPayload = pCur->info.pCell;
  aPayload += pCur->info.nHeader;
  if( pPage->intKey ){
    nKey = 0;
................................................................................

/*
** For the entry that cursor pCur is point to, return as
** many bytes of the key or data as are available on the local
** b-tree page.  Write the number of available bytes into *pAmt.
**
** The pointer returned is ephemeral.  The key/data may move
** or be destroyed on the next call to any Btree routine,
** including calls from other threads against the same cache.
** Hence, a mutex on the BtShared should be held prior to calling
** this routine.
**
** These routines is used to get quick access to key and data
** in the common case where no overflow pages are used.
*/
const void *sqlite3BtreeKeyFetch(BtCursor *pCur, int *pAmt){
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 0);
  }
  return 0;
}
const void *sqlite3BtreeDataFetch(BtCursor *pCur, int *pAmt){
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  if( pCur->eState==CURSOR_VALID ){
    return (const void*)fetchPayload(pCur, pAmt, 1);
  }
  return 0;
}


................................................................................
*/
static int moveToChild(BtCursor *pCur, u32 newPgno){
  int rc;
  MemPage *pNewPage;
  MemPage *pOldPage;
  BtShared *pBt = pCur->pBtree->pBt;

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pCur->eState==CURSOR_VALID );
  rc = getAndInitPage(pBt, newPgno, &pNewPage, pCur->pPage);
  if( rc ) return rc;
  pNewPage->idxParent = pCur->idx;
  pOldPage = pCur->pPage;
  pOldPage->idxShift = 0;
  releasePage(pOldPage);
................................................................................
** The virtual root page is the root page for most tables.  But
** for the table rooted on page 1, sometime the real root page
** is empty except for the right-pointer.  In such cases the
** virtual root page is the page that the right-pointer of page
** 1 is pointing to.
*/
int sqlite3BtreeIsRootPage(MemPage *pPage){
  MemPage *pParent;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pParent = pPage->pParent;
  if( pParent==0 ) return 1;
  if( pParent->pgno>1 ) return 0;
  if( get2byte(&pParent->aData[pParent->hdrOffset+3])==0 ) return 1;
  return 0;
}

/*
................................................................................
** the largest cell index.
*/
void sqlite3BtreeMoveToParent(BtCursor *pCur){
  MemPage *pParent;
  MemPage *pPage;
  int idxParent;

  sqlite3BtreeEnter(pCur->pBtree);
  assert( pCur->eState==CURSOR_VALID );
  pPage = pCur->pPage;
  assert( pPage!=0 );
  assert( !sqlite3BtreeIsRootPage(pPage) );
  pParent = pPage->pParent;
  assert( pParent!=0 );
  idxParent = pPage->idxParent;
  sqlite3PagerRef(pParent->pDbPage);
  releasePage(pPage);
  pCur->pPage = pParent;
  pCur->info.nSize = 0;
  assert( pParent->idxShift==0 );
  pCur->idx = idxParent;
  sqlite3BtreeLeave(pCur->pBtree);
}

/*
** Move the cursor to the root page
*/
static int moveToRoot(BtCursor *pCur){
  MemPage *pRoot;
  int rc = SQLITE_OK;
  Btree *p = pCur->pBtree;
  BtShared *pBt = p->pBt;

  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pCur->eState==CURSOR_REQUIRESEEK ){
    clearCursorPosition(pCur);
  }
  pRoot = pCur->pPage;
  if( pRoot && pRoot->pgno==pCur->pgnoRoot ){
    assert( pRoot->isInit );
  }else{
................................................................................
** entry to which it is currently pointing.
**
** The left-most leaf is the one with the smallest key - the first
** in ascending order.
*/
static int moveToLeftmost(BtCursor *pCur){
  Pgno pgno;
  int rc = SQLITE_OK;
  MemPage *pPage;

  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->mutex) );
  assert( pCur->eState==CURSOR_VALID );
  while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){
    assert( pCur->idx>=0 && pCur->idx<pPage->nCell );
    pgno = get4byte(findCell(pPage, pCur->idx));
    rc = moveToChild(pCur, pgno);

  }
  return rc;
}

/*
** Move the cursor down to the right-most leaf entry beneath the
** page to which it is currently pointing.  Notice the difference
** between moveToLeftmost() and moveToRightmost().  moveToLeftmost()
** finds the left-most entry beneath the *entry* whereas moveToRightmost()
................................................................................
** finds the right-most entry beneath the *page*.
**
** The right-most entry is the one with the largest key - the last
** key in ascending order.
*/
static int moveToRightmost(BtCursor *pCur){
  Pgno pgno;
  int rc = SQLITE_OK;
  MemPage *pPage;

  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->mutex) );
  assert( pCur->eState==CURSOR_VALID );
  while( rc==SQLITE_OK && !(pPage = pCur->pPage)->leaf ){
    pgno = get4byte(&pPage->aData[pPage->hdrOffset+8]);
    pCur->idx = pPage->nCell;
    rc = moveToChild(pCur, pgno);

  }
  if( rc==SQLITE_OK ){
    pCur->idx = pPage->nCell - 1;
    pCur->info.nSize = 0;
  }
  return SQLITE_OK;
}

/* Move the cursor to the first entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeFirst(BtCursor *pCur, int *pRes){
  int rc;

  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->mutex) );
  rc = moveToRoot(pCur);

  if( rc==SQLITE_OK ){
    if( pCur->eState==CURSOR_INVALID ){
      assert( pCur->pPage->nCell==0 );
      *pRes = 1;
      rc = SQLITE_OK;

    }else{
      assert( pCur->pPage->nCell>0 );
      *pRes = 0;
      rc = moveToLeftmost(pCur);
    }
  }
  return rc;
}

/* Move the cursor to the last entry in the table.  Return SQLITE_OK
** on success.  Set *pRes to 0 if the cursor actually points to something
** or set *pRes to 1 if the table is empty.
*/
int sqlite3BtreeLast(BtCursor *pCur, int *pRes){
  int rc;
 
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->mutex) );
  rc = moveToRoot(pCur);

  if( rc==SQLITE_OK ){
    if( CURSOR_INVALID==pCur->eState ){
      assert( pCur->pPage->nCell==0 );
      *pRes = 1;


    }else{
      assert( pCur->eState==CURSOR_VALID );
      *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
................................................................................
**                  and the cursor is therefore left point to nothing.
**
**     *pRes==0     The cursor is left pointing at an entry that
**                  exactly matches pKey.
**
**     *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;

  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->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;
  }
................................................................................
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
        }else{
          pCellKey = sqlite3_malloc( nCellKey );
          if( pCellKey==0 ) return SQLITE_NOMEM;
          rc = sqlite3BtreeKey(pCur, 0, nCellKey, (void *)pCellKey);
          c = pCur->xCompare(pCur->pArg, nCellKey, pCellKey, nKey, pKey);
          sqlite3_free(pCellKey);
          if( rc ){
            return rc;
          }
        }
      }
      if( c==0 ){
        if( pPage->leafData && !pPage->leaf ){
          lwr = pCur->idx;
          upr = lwr - 1;
          break;
................................................................................
    rc = moveToChild(pCur, chldPg);
    if( rc ){
      return rc;
    }
  }
  /* NOT REACHED */
}


/*
** Return TRUE if the cursor is not pointing at an entry of the table.
**
** TRUE will be returned after a call to sqlite3BtreeNext() moves
** past the last entry in the table or sqlite3BtreePrev() moves past
** the first entry.  TRUE is also returned if the table is empty.
................................................................................

/*
** 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.
*/
static int btreeNext(BtCursor *pCur, int *pRes){
  int rc;
  MemPage *pPage;

  rc = restoreOrClearCursorPosition(pCur);
  if( rc!=SQLITE_OK ){
    return rc;
  }
................................................................................
      *pRes = 0;
      return rc;
    }
    do{
      if( sqlite3BtreeIsRootPage(pPage) ){
        *pRes = 1;
        pCur->eState = CURSOR_INVALID;
        cursorLeave(pCur);
        return SQLITE_OK;
      }
      sqlite3BtreeMoveToParent(pCur);
      pPage = pCur->pPage;
    }while( pCur->idx>=pPage->nCell );
    *pRes = 0;
    if( pPage->leafData ){
................................................................................
  *pRes = 0;
  if( pPage->leaf ){
    return SQLITE_OK;
  }
  rc = moveToLeftmost(pCur);
  return rc;
}
int sqlite3BtreeNext(BtCursor *pCur, int *pRes){
  int rc;
  cursorEnter(pCur);
  rc = btreeNext(pCur, pRes);
  cursorLeave(pCur);
  return rc;
}


/*
** Step the cursor to the back to the previous entry in the database.  If
** successful 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.
*/
static int btreePrevious(BtCursor *pCur, int *pRes){
  int rc;
  Pgno pgno;
  MemPage *pPage;

  rc = restoreOrClearCursorPosition(pCur);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................

  pPage = pCur->pPage;
  assert( pPage->isInit );
  assert( pCur->idx>=0 );
  if( !pPage->leaf ){
    pgno = get4byte( findCell(pPage, pCur->idx) );
    rc = moveToChild(pCur, pgno);
    if( rc ){
      return rc;
    }
    rc = moveToRightmost(pCur);
  }else{
    while( pCur->idx==0 ){
      if( sqlite3BtreeIsRootPage(pPage) ){
        pCur->eState = CURSOR_INVALID;
        *pRes = 1;
        return SQLITE_OK;
................................................................................
      rc = sqlite3BtreePrevious(pCur, pRes);
    }else{
      rc = SQLITE_OK;
    }
  }
  *pRes = 0;
  return rc;
}
int sqlite3BtreePrevious(BtCursor *pCur, int *pRes){
  int rc;
  cursorEnter(pCur);
  rc = btreePrevious(pCur, pRes);
  cursorLeave(pCur);
  return rc;
}

/*
** Allocate a new page from the database file.
**
** The new page is marked as dirty.  (In other words, sqlite3PagerWrite()
** has already been called on the new page.)  The new page has also
................................................................................
  MemPage *pPage1;
  int rc;
  int n;     /* Number of pages on the freelist */
  int k;     /* Number of leaves on the trunk of the freelist */
  MemPage *pTrunk = 0;
  MemPage *pPrevTrunk = 0;

  assert( sqlite3_mutex_held(pBt->mutex) );
  pPage1 = pBt->pPage1;
  n = get4byte(&pPage1->aData[36]);
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */
    Pgno iTrunk;
    u8 searchList = 0; /* If the free-list must be searched for 'nearby' */
    
................................................................................
*/
static int freePage(MemPage *pPage){
  BtShared *pBt = pPage->pBt;
  MemPage *pPage1 = pBt->pPage1;
  int rc, n, k;

  /* Prepare the page for freeing */
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  assert( pPage->pgno>1 );
  pPage->isInit = 0;
  releasePage(pPage->pParent);
  pPage->pParent = 0;

  /* Increment the free page count on pPage1 */
  rc = sqlite3PagerWrite(pPage1->pDbPage);
................................................................................
  BtShared *pBt = pPage->pBt;
  CellInfo info;
  Pgno ovflPgno;
  int rc;
  int nOvfl;
  int ovflPageSize;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  sqlite3BtreeParseCellPtr(pPage, pCell, &info);
  if( info.iOverflow==0 ){
    return SQLITE_OK;  /* No overflow pages. Return without doing anything */
  }
  ovflPgno = get4byte(&pCell[info.iOverflow]);
  ovflPageSize = pBt->usableSize - 4;
  nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
................................................................................
  MemPage *pToRelease = 0;
  unsigned char *pPrior;
  unsigned char *pPayload;
  BtShared *pBt = pPage->pBt;
  Pgno pgnoOvfl = 0;
  int nHeader;
  CellInfo info;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* Fill in the header. */
  nHeader = 0;
  if( !pPage->leaf ){
    nHeader += 4;
  }
  if( pPage->hasData ){
................................................................................
** given in the second argument so that MemPage.pParent holds the
** pointer in the third argument.
*/
static int reparentPage(BtShared *pBt, Pgno pgno, MemPage *pNewParent, int idx){
  MemPage *pThis;
  DbPage *pDbPage;

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pNewParent!=0 );
  if( pgno==0 ) return SQLITE_OK;
  assert( pBt->pPager!=0 );
  pDbPage = sqlite3PagerLookup(pBt->pPager, pgno);
  if( pDbPage ){
    pThis = (MemPage *)sqlite3PagerGetExtra(pDbPage);
    if( pThis->isInit ){
................................................................................
** another.
*/
static int reparentChildPages(MemPage *pPage){
  int i;
  BtShared *pBt = pPage->pBt;
  int rc = SQLITE_OK;

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( pPage->leaf ) return SQLITE_OK;

  for(i=0; i<pPage->nCell; i++){
    u8 *pCell = findCell(pPage, i);
    if( !pPage->leaf ){
      rc = reparentPage(pBt, get4byte(pCell), pPage, i);
      if( rc!=SQLITE_OK ) return rc;
................................................................................
  int pc;         /* Offset to cell content of cell being deleted */
  u8 *data;       /* pPage->aData */
  u8 *ptr;        /* Used to move bytes around within data[] */

  assert( idx>=0 && idx<pPage->nCell );
  assert( sz==cellSize(pPage, idx) );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  data = pPage->aData;
  ptr = &data[pPage->cellOffset + 2*idx];
  pc = get2byte(ptr);
  assert( pc>10 && pc+sz<=pPage->pBt->usableSize );
  freeSpace(pPage, pc, sz);
  for(i=idx+1; i<pPage->nCell; i++, ptr+=2){
    ptr[0] = ptr[2];
................................................................................
  int cellOffset;   /* Address of first cell pointer in data[] */
  u8 *data;         /* The content of the whole page */
  u8 *ptr;          /* Used for moving information around in data[] */

  assert( i>=0 && i<=pPage->nCell+pPage->nOverflow );
  assert( sz==cellSizePtr(pPage, pCell) );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( pPage->nOverflow || sz+2>pPage->nFree ){
    if( pTemp ){
      memcpy(pTemp+nSkip, pCell+nSkip, sz-nSkip);
      pCell = pTemp;
    }
    j = pPage->nOverflow++;
    assert( j<sizeof(pPage->aOvfl)/sizeof(pPage->aOvfl[0]) );
................................................................................
  int totalSize;    /* Total size of all cells */
  int hdr;          /* Index of page header */
  int cellptr;      /* Address of next cell pointer */
  int cellbody;     /* Address of next cell body */
  u8 *data;         /* Data for the page */

  assert( pPage->nOverflow==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  totalSize = 0;
  for(i=0; i<nCell; i++){
    totalSize += aSize[i];
  }
  assert( totalSize+2*nCell<=pPage->nFree );
  assert( pPage->nCell==0 );
  cellptr = pPage->cellOffset;
................................................................................
  u8 *pCell;
  int szCell;
  CellInfo info;
  BtShared *pBt = pPage->pBt;
  int parentIdx = pParent->nCell;   /* pParent new divider cell index */
  int parentSize;                   /* Size of new divider cell */
  u8 parentCell[64];                /* Space for the new divider cell */

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* Allocate a new page. Insert the overflow cell from pPage
  ** into it. Then remove the overflow cell from pPage.
  */
  rc = allocateBtreePage(pBt, &pNew, &pgnoNew, 0, 0);
  if( rc!=SQLITE_OK ){
    return rc;
................................................................................
  u8 **apCell = 0;             /* All cells begin balanced */
  int *szCell;                 /* Local size of all cells in apCell[] */
  u8 *aCopy[NB];               /* Space for holding data of apCopy[] */
  u8 *aSpace;                  /* Space to hold copies of dividers cells */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 *aFrom = 0;
#endif

  assert( sqlite3_mutex_held(pPage->pBt->mutex) );

  /* 
  ** Find the parent page.
  */
  assert( pPage->isInit );
  assert( sqlite3PagerIswriteable(pPage->pDbPage) );
  pBt = pPage->pBt;
................................................................................
  BtShared *pBt;                  /* The main BTree structure */
  int mxCellPerPage;           /* Maximum number of cells per page */
  u8 **apCell;                 /* All cells from pages being balanced */
  int *szCell;                 /* Local size of all cells */

  assert( pPage->pParent==0 );
  assert( pPage->nCell==0 );
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  pBt = pPage->pBt;
  mxCellPerPage = MX_CELL(pBt);
  apCell = sqlite3_malloc( mxCellPerPage*(sizeof(u8*)+sizeof(int)) );
  if( apCell==0 ) return SQLITE_NOMEM;
  szCell = (int*)&apCell[mxCellPerPage];
  if( pPage->leaf ){
    /* The table is completely empty */
................................................................................
  u8 *cdata;          /* Content of the child page */
  int hdr;            /* Offset to page header in parent */
  int brk;            /* Offset to content of first cell in parent */

  assert( pPage->pParent==0 );
  assert( pPage->nOverflow>0 );
  pBt = pPage->pBt;
  assert( sqlite3_mutex_held(pBt->mutex) );
  rc = allocateBtreePage(pBt, &pChild, &pgnoChild, pPage->pgno, 0);
  if( rc ) return rc;
  assert( sqlite3PagerIswriteable(pChild->pDbPage) );
  usableSize = pBt->usableSize;
  data = pPage->aData;
  hdr = pPage->hdrOffset;
  brk = get2byte(&data[hdr+5]);
................................................................................

/*
** Decide if the page pPage needs to be balanced.  If balancing is
** required, call the appropriate balancing routine.
*/
static int balance(MemPage *pPage, int insert){
  int rc = SQLITE_OK;
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  if( pPage->pParent==0 ){
    if( pPage->nOverflow>0 ){
      rc = balance_deeper(pPage);
    }
    if( rc==SQLITE_OK && pPage->nCell==0 ){
      rc = balance_shallower(pPage);
    }
................................................................................
** a page entirely and we do not want to leave any cursors 
** pointing to non-existant pages or cells.
*/
static int checkReadLocks(Btree *pBtree, Pgno pgnoRoot, BtCursor *pExclude){
  BtCursor *p;
  BtShared *pBt = pBtree->pBt;
  sqlite3 *db = pBtree->pSqlite;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3_mutex_held(db->mutex) );
  for(p=pBt->pCursor; p; p=p->pNext){
    if( p==pExclude ) continue;
    if( p->eState!=CURSOR_VALID ) continue;
    if( p->pgnoRoot!=pgnoRoot ) continue;
    if( p->wrFlag==0 ){
      sqlite3 *dbOther = p->pBtree->pSqlite;
      if( dbOther==0 ||
................................................................................
  int nZero,                     /* Number of extra 0 bytes to append to data */
  int appendBias                 /* True if this is likely an append */
){
  int rc;
  int loc;
  int szNew;
  MemPage *pPage;
  Btree *p = pCur->pBtree;
  BtShared *pBt = p->pBt;
  unsigned char *oldCell;
  unsigned char *newCell = 0;

  sqlite3BtreeEnter(p);
  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction before doing an insert */
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
    sqlite3BtreeLeave(p);
    return rc;
  }
  assert( !pBt->readOnly );
  if( !pCur->wrFlag ){
    sqlite3BtreeLeave(p);
    return SQLITE_PERM;   /* Cursor not open for writing */
  }
  if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){
    sqlite3BtreeLeave(p);
    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* 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))
  ){
    sqlite3BtreeLeave(p);
    return rc;
  }

  pPage = pCur->pPage;
  assert( pPage->intKey || nKey>=0 );
  assert( pPage->leaf || !pPage->leafData );
  TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
          pCur->pgnoRoot, nKey, nData, pPage->pgno,
          loc==0 ? "overwrite" : "new entry"));
  assert( pPage->isInit );
  rc = sqlite3PagerWrite(pPage->pDbPage);
  if( rc ){
    sqlite3BtreeLeave(p);
    return rc;
  }
  newCell = sqlite3_malloc( MX_CELL_SIZE(pBt) );
  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) );
  if( loc==0 && CURSOR_VALID==pCur->eState ){
................................................................................
  /* sqlite3BtreePageDump(pCur->pBt, pCur->pgnoRoot, 1); */
  /* fflush(stdout); */
  if( rc==SQLITE_OK ){
    moveToRoot(pCur);
  }
end_insert:
  sqlite3_free(newCell);
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Delete the entry that the cursor is pointing to.  The cursor
** is left pointing at a random location.
*/
int sqlite3BtreeDelete(BtCursor *pCur){
  MemPage *pPage = pCur->pPage;
  unsigned char *pCell;
  int rc;
  Pgno pgnoChild = 0;
  Btree *p = pCur->pBtree;
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);
  assert( pPage->isInit );
  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction before doing a delete */
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
    sqlite3BtreeLeave(p);
    return rc;
  }
  assert( !pBt->readOnly );
  if( pCur->idx >= pPage->nCell ){
    sqlite3BtreeLeave(p);
    return SQLITE_ERROR;  /* The cursor is not pointing to anything */
  }
  if( !pCur->wrFlag ){
    sqlite3BtreeLeave(p);
    return SQLITE_PERM;   /* Did not open this cursor for writing */
  }
  if( checkReadLocks(pCur->pBtree, pCur->pgnoRoot, pCur) ){
    sqlite3BtreeLeave(p);
    return SQLITE_LOCKED; /* The table pCur points to has a read lock */
  }

  /* Restore the current cursor position (a no-op if the cursor is not in 
  ** CURSOR_REQUIRESEEK state) and save the positions of any other cursors 
  ** open on the same table. Then call sqlite3PagerWrite() on the page
  ** that the entry will be deleted from.
  */
  if( 
    (rc = restoreOrClearCursorPosition(pCur))!=0 ||
    (rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur))!=0 ||
    (rc = sqlite3PagerWrite(pPage->pDbPage))!=0
  ){
    sqlite3BtreeLeave(p);
    return rc;
  }

  /* Locate the cell within it's page and leave pCell pointing to the
  ** data. The clearCell() call frees any overflow pages associated with the
  ** cell. The cell itself is still intact.
  */
  pCell = findCell(pPage, pCur->idx);
  if( !pPage->leaf ){
    pgnoChild = get4byte(pCell);
  }
  rc = clearCell(pPage, pCell);
  if( rc ){
    sqlite3BtreeLeave(p);
    return rc;
  }

  if( !pPage->leaf ){
    /*
    ** The entry we are about to delete is not a leaf so if we do not
    ** do something we will leave a hole on an internal page.
    ** 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
................................................................................
       pCur->pgnoRoot, pPage->pgno));
    dropCell(pPage, pCur->idx, cellSizePtr(pPage, pCell));
    rc = balance(pPage, 0);
  }
  if( rc==SQLITE_OK ){
    moveToRoot(pCur);
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Create a new BTree table.  Write into *piTable the page
** number for the root page of the new table.
**
................................................................................
** The type of type is determined by the flags parameter.  Only the
** following values of flags are currently in use.  Other values for
** flags might not work:
**
**     BTREE_INTKEY|BTREE_LEAFDATA     Used for SQL tables with rowid keys
**     BTREE_ZERODATA                  Used for SQL indices
*/
static int btreeCreateTable(Btree *p, int *piTable, int flags){
  BtShared *pBt = p->pBt;
  MemPage *pRoot;
  Pgno pgnoRoot;
  int rc;

  if( pBt->inTransaction!=TRANS_WRITE ){
    /* Must start a transaction first */
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
    return rc;
  }
  assert( !pBt->readOnly );

#ifdef SQLITE_OMIT_AUTOVACUUM
  rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
  if( rc ){
    return rc;
  }
#else
  if( pBt->autoVacuum ){
    Pgno pgnoMove;      /* Move a page here to make room for the root-page */
    MemPage *pPageMove; /* The page to move to. */

    /* Creating a new table may probably require moving an existing database
    ** to make room for the new tables root page. In case this page turns
................................................................................
    invalidateAllOverflowCache(pBt);

    /* Read the value of meta[3] from the database to determine where the
    ** root page of the new table should go. meta[3] is the largest root-page
    ** created so far, so the new root-page is (meta[3]+1).
    */
    rc = sqlite3BtreeGetMeta(p, 4, &pgnoRoot);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    pgnoRoot++;

    /* The new root-page may not be allocated on a pointer-map page, or the
    ** PENDING_BYTE page.
    */
    if( pgnoRoot==PTRMAP_PAGENO(pBt, pgnoRoot) ||
        pgnoRoot==PENDING_BYTE_PAGE(pBt) ){
................................................................................
#endif
  assert( sqlite3PagerIswriteable(pRoot->pDbPage) );
  zeroPage(pRoot, flags | PTF_LEAF);
  sqlite3PagerUnref(pRoot->pDbPage);
  *piTable = (int)pgnoRoot;
  return SQLITE_OK;
}
int sqlite3BtreeCreateTable(Btree *p, int *piTable, int flags){
  int rc;
  sqlite3BtreeEnter(p);
  rc = btreeCreateTable(p, piTable, flags);
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Erase the given database page and all its children.  Return
** the page to the freelist.
*/
static int clearDatabasePage(
  BtShared *pBt,           /* The BTree that contains the table */
................................................................................
  int freePageFlag      /* Deallocate page if true */
){
  MemPage *pPage = 0;
  int rc;
  unsigned char *pCell;
  int i;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno>sqlite3PagerPagecount(pBt->pPager) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage, pParent);
  if( rc ) goto cleardatabasepage_out;
  for(i=0; i<pPage->nCell; i++){
................................................................................
** This routine will fail with SQLITE_LOCKED if there are any open
** read cursors on the table.  Open write cursors are moved to the
** root of the table.
*/
int sqlite3BtreeClearTable(Btree *p, int iTable){
  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  if( p->inTrans!=TRANS_WRITE ){
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;

  }else if( (rc = checkReadLocks(p, iTable, 0))!=SQLITE_OK ){
    /* nothing to do */
  }else if( SQLITE_OK!=(rc = saveAllCursors(pBt, iTable, 0)) ){
    /* nothing to do */
  }else{
    rc = clearDatabasePage(pBt, (Pgno)iTable, 0, 0);
  }



  sqlite3BtreeLeave(p);
  return rc;



}

/*
** Erase all information in a table and add the root of the table to
** the freelist.  Except, the root of the principle table (the one on
** page 1) is never added to the freelist.
**
................................................................................
** root pages are kept at the beginning of the database file, which
** is necessary for AUTOVACUUM to work right.  *piMoved is set to the 
** page number that used to be the last root page in the file before
** the move.  If no page gets moved, *piMoved is set to 0.
** The last root page is recorded in meta[3] and the value of
** meta[3] is updated by this procedure.
*/
static int btreeDropTable(Btree *p, int iTable, int *piMoved){
  int rc;
  MemPage *pPage = 0;
  BtShared *pBt = p->pBt;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( p->inTrans!=TRANS_WRITE ){
    return pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;
  }

  /* It is illegal to drop a table if any cursors are open on the
  ** database. This is because in auto-vacuum mode the backend may
  ** need to move another root-page to fill a gap left by the deleted
................................................................................
  }else{
    /* If sqlite3BtreeDropTable was called on page 1. */
    zeroPage(pPage, PTF_INTKEY|PTF_LEAF );
    releasePage(pPage);
  }
  return rc;  
}
int sqlite3BtreeDropTable(Btree *p, int iTable, int *piMoved){
  int rc;
  sqlite3BtreeEnter(p);
  rc = btreeDropTable(p, iTable, piMoved);
  sqlite3BtreeLeave(p);
  return rc;
}


/*
** Read the meta-information out of a database file.  Meta[0]
** is the number of free pages currently in the database.  Meta[1]
** through meta[15] are available for use by higher layers.  Meta[0]
** is read-only, the others are read/write.
................................................................................
** free pages is not visible.  So Cookie[0] is the same as Meta[1].
*/
int sqlite3BtreeGetMeta(Btree *p, int idx, u32 *pMeta){
  DbPage *pDbPage;
  int rc;
  unsigned char *pP1;
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);

  /* Reading a meta-data value requires a read-lock on page 1 (and hence
  ** the sqlite_master table. We grab this lock regardless of whether or
  ** not the SQLITE_ReadUncommitted flag is set (the table rooted at page
  ** 1 is treated as a special case by queryTableLock() and lockTable()).
  */
  rc = queryTableLock(p, 1, READ_LOCK);
  if( rc!=SQLITE_OK ){
    sqlite3BtreeLeave(p);
    return rc;
  }

  assert( idx>=0 && idx<=15 );
  rc = sqlite3PagerGet(pBt->pPager, 1, &pDbPage);
  if( rc ){
    sqlite3BtreeLeave(p);
    return rc;
  }
  pP1 = (unsigned char *)sqlite3PagerGetData(pDbPage);
  *pMeta = get4byte(&pP1[36 + idx*4]);
  sqlite3PagerUnref(pDbPage);

  /* If autovacuumed is disabled in this build but we are trying to 
  ** access an autovacuumed database, then make the database readonly. 
  */
#ifdef SQLITE_OMIT_AUTOVACUUM
  if( idx==4 && *pMeta>0 ) pBt->readOnly = 1;
#endif

  /* Grab the read-lock on page 1. */
  rc = lockTable(p, 1, READ_LOCK);
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Write meta-information back into the database.  Meta[0] is
** read-only and may not be written.
*/
int sqlite3BtreeUpdateMeta(Btree *p, int idx, u32 iMeta){
  BtShared *pBt = p->pBt;
  unsigned char *pP1;
  int rc;
  assert( idx>=1 && idx<=15 );
  sqlite3BtreeEnter(p);
  if( p->inTrans!=TRANS_WRITE ){
    rc = pBt->readOnly ? SQLITE_READONLY : SQLITE_ERROR;

  }else{
    assert( pBt->pPage1!=0 );
    pP1 = pBt->pPage1->aData;
    rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);

    if( rc==SQLITE_OK ){
      put4byte(&pP1[36 + idx*4], iMeta);
      if( idx==7 ){
        assert( pBt->autoVacuum || iMeta==0 );
        assert( iMeta==0 || iMeta==1 );
        pBt->incrVacuum = iMeta;
      }
    }
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** Return the flag byte at the beginning of the page that the cursor
** is currently pointing to.
*/
int sqlite3BtreeFlags(BtCursor *pCur){
  /* TODO: What about CURSOR_REQUIRESEEK state? Probably need to call
  ** restoreOrClearCursorPosition() here.
  */
  MemPage *pPage = pCur->pPage;
  assert( sqlite3_mutex_held(pPage->pBt->mutex) );
  return pPage ? pPage->aData[pPage->hdrOffset] : 0;
}


/*
** Return the pager associated with a BTree.  This routine is used for
** testing and debugging only.
*/
Pager *sqlite3BtreePager(Btree *p){
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  return p->pBt->pPager;
}

#ifndef SQLITE_OMIT_INTEGRITY_CHECK
/*
** Append a message to the error message string.
*/
................................................................................
  int *pnErr    /* Write number of errors seen to this variable */
){
  int i;
  int nRef;
  IntegrityCk sCheck;
  BtShared *pBt = p->pBt;

  sqlite3BtreeEnter(p);
  nRef = sqlite3PagerRefcount(pBt->pPager);
  if( lockBtreeWithRetry(p)!=SQLITE_OK ){
    sqlite3BtreeLeave(p);
    return sqlite3StrDup("Unable to acquire a read lock on the database");
  }
  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = sqlite3PagerPagecount(sCheck.pPager);
  sCheck.mxErr = mxErr;
  sCheck.nErr = 0;
................................................................................
#ifndef SQLITE_OMIT_AUTOVACUUM
  if( pBt->nTrunc!=0 ){
    sCheck.nPage = pBt->nTrunc;
  }
#endif
  if( sCheck.nPage==0 ){
    unlockBtreeIfUnused(pBt);
    sqlite3BtreeLeave(p);
    return 0;
  }
  sCheck.anRef = sqlite3_malloc( (sCheck.nPage+1)*sizeof(sCheck.anRef[0]) );
  if( !sCheck.anRef ){
    unlockBtreeIfUnused(pBt);
    *pnErr = 1;
    sqlite3BtreeLeave(p);
    return sqlite3MPrintf(p->pSqlite, "Unable to malloc %d bytes", 
        (sCheck.nPage+1)*sizeof(sCheck.anRef[0]));
  }
  for(i=0; i<=sCheck.nPage; i++){ sCheck.anRef[i] = 0; }
  i = PENDING_BYTE_PAGE(pBt);
  if( i<=sCheck.nPage ){
    sCheck.anRef[i] = 1;
................................................................................
      "Outstanding page count goes from %d to %d during this analysis",
      nRef, sqlite3PagerRefcount(pBt->pPager)
    );
  }

  /* Clean  up and report errors.
  */
  sqlite3BtreeLeave(p);
  sqlite3_free(sCheck.anRef);
  *pnErr = sCheck.nErr;
  return sCheck.zErrMsg;
}
#endif /* SQLITE_OMIT_INTEGRITY_CHECK */

/*
** Return the full pathname of the underlying database file.
*/
const char *sqlite3BtreeGetFilename(Btree *p){
  assert( p->pBt->pPager!=0 );
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  return sqlite3PagerFilename(p->pBt->pPager);
}

/*
** Return the pathname of the directory that contains the database file.
*/
const char *sqlite3BtreeGetDirname(Btree *p){
  assert( p->pBt->pPager!=0 );
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  return sqlite3PagerDirname(p->pBt->pPager);
}

/*
** Return the pathname of the journal file for this database. The return
** value of this routine is the same regardless of whether the journal file
** has been created or not.
*/
const char *sqlite3BtreeGetJournalname(Btree *p){
  assert( p->pBt->pPager!=0 );
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  return sqlite3PagerJournalname(p->pBt->pPager);
}

#ifndef SQLITE_OMIT_VACUUM
/*
** Copy the complete content of pBtFrom into pBtTo.  A transaction
** must be active for both files.
**
** The size of file pBtFrom may be reduced by this operation.
** If anything goes wrong, the transaction on pBtFrom is rolled back.
*/
static int btreeCopyFile(Btree *pTo, Btree *pFrom){
  int rc = SQLITE_OK;
  Pgno i, nPage, nToPage, iSkip;

  BtShared *pBtTo = pTo->pBt;
  BtShared *pBtFrom = pFrom->pBt;

  if( pTo->inTrans!=TRANS_WRITE || pFrom->inTrans!=TRANS_WRITE ){
................................................................................
  }

  if( rc ){
    sqlite3BtreeRollback(pTo);
  }
  return rc;  
}
int sqlite3BtreeCopyFile(Btree *pTo, Btree *pFrom){
  int rc;
  sqlite3BtreeEnter(pTo);
  sqlite3BtreeEnter(pFrom);
  rc = btreeCopyFile(pTo, pFrom);
  sqlite3BtreeLeave(pFrom);
  sqlite3BtreeLeave(pTo);
  return rc;
}

#endif /* SQLITE_OMIT_VACUUM */

/*
** Return non-zero if a transaction is active.
*/
int sqlite3BtreeIsInTrans(Btree *p){
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  return (p && (p->inTrans==TRANS_WRITE));
}

/*
** Return non-zero if a statement transaction is active.
*/
int sqlite3BtreeIsInStmt(Btree *p){
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  return (p->pBt && p->pBt->inStmt);
}

/*
** Return non-zero if a read (or write) transaction is active.
*/
int sqlite3BtreeIsInReadTrans(Btree *p){
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  return (p && (p->inTrans!=TRANS_NONE));
}

/*
** This function returns a pointer to a blob of memory associated with
** a single shared-btree. The memory is used by client code for it's own
** purposes (for example, to store a high-level schema associated with 
................................................................................
** Just before the shared-btree is closed, the function passed as the 
** xFree argument when the memory allocation was made is invoked on the 
** blob of allocated memory. This function should not call sqlite3_free()
** on the memory, the btree layer does that.
*/
void *sqlite3BtreeSchema(Btree *p, int nBytes, void(*xFree)(void *)){
  BtShared *pBt = p->pBt;
  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  if( !pBt->pSchema ){
    pBt->pSchema = sqlite3MallocZero(nBytes);
    pBt->xFreeSchema = xFree;
  }
  return pBt->pSchema;
}

/*
** Return true if another user of the same shared btree as the argument
** handle holds an exclusive lock on the sqlite_master table.
*/
int sqlite3BtreeSchemaLocked(Btree *p){
  assert( sqlite3_mutex_held(p->pBt->mutex) );
  assert( sqlite3_mutex_held(p->pSqlite->mutex) );
  return (queryTableLock(p, MASTER_ROOT, READ_LOCK)!=SQLITE_OK);
}


#ifndef SQLITE_OMIT_SHARED_CACHE
/*
** Obtain a lock on the table whose root page is iTab.  The
** lock is a write lock if isWritelock is true or a read lock
** if it is false.
*/
int sqlite3BtreeLockTable(Btree *p, int iTab, u8 isWriteLock){
  int rc = SQLITE_OK;
  u8 lockType = (isWriteLock?WRITE_LOCK:READ_LOCK);
  sqlite3BtreeEnter(p);
  rc = queryTableLock(p, iTab, lockType);
  if( rc==SQLITE_OK ){
    rc = lockTable(p, iTab, lockType);
  }
  sqlite3BtreeLeave(p);
  return rc;
}
#endif

#ifndef SQLITE_OMIT_INCRBLOB
/*
** Argument pCsr must be a cursor opened for writing on an 
** INTKEY table currently pointing at a valid table entry. 
** This function modifies the data stored as part of that entry.
** Only the data content may only be modified, it is not possible
** to change the length of the data stored.
*/
int sqlite3BtreePutData(BtCursor *pCsr, u32 offset, u32 amt, void *z){
  assert( sqlite3_mutex_held(pCsr->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCsr->pBtree->pSqlite->mutex) );
  assert(pCsr->isIncrblobHandle);
  if( pCsr->eState==CURSOR_REQUIRESEEK ){
    return SQLITE_ABORT;
  }

  /* Check some preconditions: 
  **   (a) the cursor is open for writing,
................................................................................
**
** This function sets a flag only. The actual page location cache
** (stored in BtCursor.aOverflow[]) is allocated and used by function
** accessPayload() (the worker function for sqlite3BtreeData() and
** sqlite3BtreePutData()).
*/
void sqlite3BtreeCacheOverflow(BtCursor *pCur){
  assert( sqlite3_mutex_held(pCur->pBtree->pBt->mutex) );
  assert( sqlite3_mutex_held(pCur->pBtree->pSqlite->mutex) );
  assert(!pCur->isIncrblobHandle);
  assert(!pCur->aOverflow);
  pCur->isIncrblobHandle = 1;
}
#endif

Changes to src/btree.h.

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**    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 1.83 2007/08/17 01:14:38 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
................................................................................
int sqlite3BtreeLockTable(Btree *, int, u8);

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
#ifdef SQLITE_OMIT_SHARED_CACHE
# define sqlite3BtreeEnter(X)
# define sqlite3BtreeLeave(X)
#else
  void sqlite3BtreeEnter(Btree*);
  void sqlite3BtreeLeave(Btree*);
#endif

const char *sqlite3BtreeGetFilename(Btree *);
const char *sqlite3BtreeGetDirname(Btree *);
const char *sqlite3BtreeGetJournalname(Btree *);
int sqlite3BtreeCopyFile(Btree *, Btree *);








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**    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 1.84 2007/08/20 22:48:42 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
................................................................................
int sqlite3BtreeLockTable(Btree *, int, u8);

/*
** If we are not using shared cache, then there is no need to
** use mutexes to access the BtShared structures.  So make the
** Enter and Leave procedures no-ops.
*/
#if SQLITE_THREADSAFE && !defined(SQLITE_OMIT_SHARED_CACHE)
  void sqlite3BtreeEnter(Btree*);
  void sqlite3BtreeLeave(Btree*);
#else
# define sqlite3BtreeEnter(X)
# define sqlite3BtreeLeave(X)
#endif

const char *sqlite3BtreeGetFilename(Btree *);
const char *sqlite3BtreeGetDirname(Btree *);
const char *sqlite3BtreeGetJournalname(Btree *);
int sqlite3BtreeCopyFile(Btree *, Btree *);

Changes to src/btreeInt.h.

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260
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264
265
266



267
268
269
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271
272
273
...
311
312
313
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315
316
317
318
319
320
321
322
323
324
325
326
...
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
** 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: btreeInt.h,v 1.7 2007/08/20 13:14:29 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.
................................................................................
** structure is appended and initialized to zero.  This structure stores
** information about the page that is decoded from the raw file page.
**
** The pParent field points back to the parent page.  This allows us to
** walk up the BTree from any leaf to the root.  Care must be taken to
** unref() the parent page pointer when this page is no longer referenced.
** The pageDestructor() routine handles that chore.



*/
struct MemPage {
  u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
  u8 idxShift;         /* True if Cell indices have changed */
  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
  u8 intKey;           /* True if intkey flag is set */
  u8 leaf;             /* True if leaf flag is set */
................................................................................
** For some database files, the same underlying database cache might be 
** shared between multiple connections.  In that case, each contection
** has it own pointer to this object.  But each instance of this object
** points to the same BtShared object.  The database cache and the
** schema associated with the database file are all contained within
** the BtShared object.
**
** All fields in this structure are accessed under the sqlite3.pMutex
** mutex.
*/
struct Btree {
  sqlite3 *pSqlite;  /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with other pSqlite */
  u8 locked;         /* True if pSqlite currently has pBt locked */
................................................................................
** The entry is identified by its MemPage and the index in
** MemPage.aCell[] of the entry.
**
** When a single database file can shared by two more database connections,
** but cursors cannot be shared.  Each cursor is associated with a
** particular database connection identified BtCursor.pBtree.pSqlite.
**
** The fields in this structure are accessed under the sqlite3.pMutex
** mutex, specifically the BtCurser.pBtree->pSqlite->pMutex mutex.
** The pNext and pPrev fields also require the BtShared.mutex mutex.
*/
struct BtCursor {
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
  int (*xCompare)(void*,int,const void*,int,const void*); /* Key comp func */
  void *pArg;               /* First arg to xCompare() */
  Pgno pgnoRoot;            /* The root page of this tree */







|







 







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<







 







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5
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...
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321

322
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326
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328
...
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
** 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: btreeInt.h,v 1.8 2007/08/20 22:48:42 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.
................................................................................
** structure is appended and initialized to zero.  This structure stores
** information about the page that is decoded from the raw file page.
**
** The pParent field points back to the parent page.  This allows us to
** walk up the BTree from any leaf to the root.  Care must be taken to
** unref() the parent page pointer when this page is no longer referenced.
** The pageDestructor() routine handles that chore.
**
** Access to all fields of this structure is controlled by the mutex
** stored in MemPage.pBt->mutex.
*/
struct MemPage {
  u8 isInit;           /* True if previously initialized. MUST BE FIRST! */
  u8 idxShift;         /* True if Cell indices have changed */
  u8 nOverflow;        /* Number of overflow cell bodies in aCell[] */
  u8 intKey;           /* True if intkey flag is set */
  u8 leaf;             /* True if leaf flag is set */
................................................................................
** For some database files, the same underlying database cache might be 
** shared between multiple connections.  In that case, each contection
** has it own pointer to this object.  But each instance of this object
** points to the same BtShared object.  The database cache and the
** schema associated with the database file are all contained within
** the BtShared object.
**
** All fields in this structure are accessed under the sqlite3.mutex.

*/
struct Btree {
  sqlite3 *pSqlite;  /* The database connection holding this btree */
  BtShared *pBt;     /* Sharable content of this btree */
  u8 inTrans;        /* TRANS_NONE, TRANS_READ or TRANS_WRITE */
  u8 sharable;       /* True if we can share pBt with other pSqlite */
  u8 locked;         /* True if pSqlite currently has pBt locked */
................................................................................
** The entry is identified by its MemPage and the index in
** MemPage.aCell[] of the entry.
**
** When a single database file can shared by two more database connections,
** but cursors cannot be shared.  Each cursor is associated with a
** particular database connection identified BtCursor.pBtree.pSqlite.
**
** Fields in this structure are accessed under the BtShared.mutex
** mutex.  The pBtree field is safe to access under the
** BtShared->pBtree->pSqlite->mutex mutex.
*/
struct BtCursor {
  Btree *pBtree;            /* The Btree to which this cursor belongs */
  BtCursor *pNext, *pPrev;  /* Forms a linked list of all cursors */
  int (*xCompare)(void*,int,const void*,int,const void*); /* Key comp func */
  void *pArg;               /* First arg to xCompare() */
  Pgno pgnoRoot;            /* The root page of this tree */

Changes to src/main.c.

10
11
12
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214
215
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...
896
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899
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903
904
905
906
907
908
909
910
....
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.388 2007/08/20 17:37:48 shess Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The version of the library
................................................................................
  /* The temp-database schema is allocated differently from the other schema
  ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
  ** So it needs to be freed here. Todo: Why not roll the temp schema into
  ** the same sqliteMalloc() as the one that allocates the database 
  ** structure?
  */
  sqlite3_free(db->aDb[1].pSchema);

  sqlite3_free(db);
  /* sqlite3ReleaseThreadData(); */
  return SQLITE_OK;
}

/*
** Rollback all database files.
*/
void sqlite3RollbackAll(sqlite3 *db){
................................................................................
  sqlite3 *db;
  int rc;
  CollSeq *pColl;

  /* Allocate the sqlite data structure */
  db = sqlite3MallocZero( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;
  db->pVfs = sqlite3_find_vfs(0);
  db->errMask = 0xff;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames
................................................................................
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3_sleep(int ms){
  sqlite3_vfs *pVfs;
  pVfs = sqlite3_find_vfs(0);

  /* This function works in milliseconds, but the underlying OsSleep() 
  ** API uses microseconds. Hence the 1000's.
  */
  return (sqlite3OsSleep(pVfs, 1000*ms)/1000);
}








|







 







>

<







 







|







 







|







10
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12
13
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...
214
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216
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219
220
221
222

223
224
225
226
227
228
229
...
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
....
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.389 2007/08/20 22:48:42 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/*
** The version of the library
................................................................................
  /* The temp-database schema is allocated differently from the other schema
  ** objects (using sqliteMalloc() directly, instead of sqlite3BtreeSchema()).
  ** So it needs to be freed here. Todo: Why not roll the temp schema into
  ** the same sqliteMalloc() as the one that allocates the database 
  ** structure?
  */
  sqlite3_free(db->aDb[1].pSchema);
  sqlite3_vfs_release(db->pVfs);
  sqlite3_free(db);

  return SQLITE_OK;
}

/*
** Rollback all database files.
*/
void sqlite3RollbackAll(sqlite3 *db){
................................................................................
  sqlite3 *db;
  int rc;
  CollSeq *pColl;

  /* Allocate the sqlite data structure */
  db = sqlite3MallocZero( sizeof(sqlite3) );
  if( db==0 ) goto opendb_out;
  db->pVfs = sqlite3_vfs_find(0);
  db->errMask = 0xff;
  db->priorNewRowid = 0;
  db->magic = SQLITE_MAGIC_BUSY;
  db->nDb = 2;
  db->aDb = db->aDbStatic;
  db->autoCommit = 1;
  db->flags |= SQLITE_ShortColNames
................................................................................
}

/*
** Sleep for a little while.  Return the amount of time slept.
*/
int sqlite3_sleep(int ms){
  sqlite3_vfs *pVfs;
  pVfs = sqlite3_vfs_find(0);

  /* This function works in milliseconds, but the underlying OsSleep() 
  ** API uses microseconds. Hence the 1000's.
  */
  return (sqlite3OsSleep(pVfs, 1000*ms)/1000);
}

Changes to src/mem2.c.

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9
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...
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369

370
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374
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376
...
435
436
437
438
439
440
441
442




















443
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem2.c,v 1.4 2007/08/16 19:40:17 drh Exp $
*/

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined and SQLITE_OMIT_MEMORY_ALLOCATION
** is not defined.
*/
................................................................................
  ** These values are used to simulate malloc failures.  When
  ** iFail is 1, simulate a malloc failures and reset the value
  ** to iReset.
  */
  int iFail;    /* Decrement and fail malloc when this is 1 */
  int iReset;   /* When malloc fails set iiFail to this value */
  int iFailCnt; /* Number of failures */






  
  
} mem = {  /* This variable holds all of the local data */
   ((sqlite3_uint64)1)<<63,    /* alarmThreshold */
   /* Everything else is initialized to zero */
};

................................................................................
  void *p;
  unsigned int totalSize;

  if( mem.mutex==0 ){
    mem.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM);
  }
  sqlite3_mutex_enter(mem.mutex);

  if( mem.nowUsed+nByte>=mem.alarmThreshold ){
    sqlite3MemsysAlarm(nByte);
  }
  nByte = (nByte+3)&~3;
  totalSize = nByte + sizeof(*pHdr) + sizeof(unsigned int) +
               mem.nBacktrace*sizeof(void*);
  if( mem.iFail>0 ){
................................................................................
  if( pPrior==0 ){
    return sqlite3_malloc(nByte);
  }
  if( nByte==0 ){
    sqlite3_free(pPrior);
    return 0;
  }

  pOldHdr = sqlite3MemsysGetHeader(pPrior);
  pNew = sqlite3_malloc(nByte);
  if( pNew ){
    memcpy(pNew, pPrior, nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize);
    if( nByte>pOldHdr->iSize ){
      memset(&((char*)pNew)[pOldHdr->iSize], 0x2b, nByte - pOldHdr->iSize);
    }
................................................................................
int sqlite3_memdebug_fail(int iFail, int iRepeat){
  int n = mem.iFailCnt;
  mem.iFail = iFail+1;
  mem.iReset = iRepeat;
  mem.iFailCnt = 0;
  return n;
}





















#endif /* SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */







|







 







>
>
>
>
>
>







 







>







 







>







 








>
>
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>
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>
>

8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
...
128
129
130
131
132
133
134
135
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139
140
141
142
143
144
145
146
147
...
256
257
258
259
260
261
262
263
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265
266
267
268
269
270
...
370
371
372
373
374
375
376
377
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380
381
382
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...
443
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447
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449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement a memory
** allocation subsystem for use by SQLite.  
**
** $Id: mem2.c,v 1.5 2007/08/20 22:48:43 drh Exp $
*/

/*
** This version of the memory allocator is used only if the
** SQLITE_MEMDEBUG macro is defined and SQLITE_OMIT_MEMORY_ALLOCATION
** is not defined.
*/
................................................................................
  ** These values are used to simulate malloc failures.  When
  ** iFail is 1, simulate a malloc failures and reset the value
  ** to iReset.
  */
  int iFail;    /* Decrement and fail malloc when this is 1 */
  int iReset;   /* When malloc fails set iiFail to this value */
  int iFailCnt; /* Number of failures */

  /* 
  ** sqlite3MallocDisallow() increments the following counter.
  ** sqlite3MallocAllow() decrements it.
  */
  int disallow; /* Do not allow memory allocation */
  
  
} mem = {  /* This variable holds all of the local data */
   ((sqlite3_uint64)1)<<63,    /* alarmThreshold */
   /* Everything else is initialized to zero */
};

................................................................................
  void *p;
  unsigned int totalSize;

  if( mem.mutex==0 ){
    mem.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MEM);
  }
  sqlite3_mutex_enter(mem.mutex);
  assert( mem.disallow==0 );
  if( mem.nowUsed+nByte>=mem.alarmThreshold ){
    sqlite3MemsysAlarm(nByte);
  }
  nByte = (nByte+3)&~3;
  totalSize = nByte + sizeof(*pHdr) + sizeof(unsigned int) +
               mem.nBacktrace*sizeof(void*);
  if( mem.iFail>0 ){
................................................................................
  if( pPrior==0 ){
    return sqlite3_malloc(nByte);
  }
  if( nByte==0 ){
    sqlite3_free(pPrior);
    return 0;
  }
  assert( mem.disallow==0 );
  pOldHdr = sqlite3MemsysGetHeader(pPrior);
  pNew = sqlite3_malloc(nByte);
  if( pNew ){
    memcpy(pNew, pPrior, nByte<pOldHdr->iSize ? nByte : pOldHdr->iSize);
    if( nByte>pOldHdr->iSize ){
      memset(&((char*)pNew)[pOldHdr->iSize], 0x2b, nByte - pOldHdr->iSize);
    }
................................................................................
int sqlite3_memdebug_fail(int iFail, int iRepeat){
  int n = mem.iFailCnt;
  mem.iFail = iFail+1;
  mem.iReset = iRepeat;
  mem.iFailCnt = 0;
  return n;
}

/*
** The following two routines are used to assert that no memory
** allocations occur between one call and the next.  The use of
** these routines does not change the computed results in any way.
** These routines are like asserts.
*/
void sqlite3MallocDisallow(void){
  assert( mem.mutex!=0 );
  sqlite3_mutex_enter(mem.mutex);
  mem.disallow++;
  sqlite3_mutex_leave(mem.mutex);
}
void sqlite3MallocAllow(void){
  assert( mem.mutex );
  sqlite3_mutex_enter(mem.mutex);
  assert( mem.disallow>0 );
  mem.disallow--;
  sqlite3_mutex_leave(mem.mutex);
}

#endif /* SQLITE_MEMDEBUG && !SQLITE_OMIT_MEMORY_ALLOCATION */

Changes to src/mutex.c.

8
9
10
11
12
13
14
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16
17
18
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20
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22
..
37
38
39
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45
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..
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72











73
74
75
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79
...
289
290
291
292
293
294
295











296
297
298
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for
** use by the SQLite core.
**
** $Id: mutex.c,v 1.4 2007/08/17 01:14:38 drh Exp $
*/

/*
** If SQLITE_MUTEX_APPDEF is defined, then this whole module is
** omitted and equivalent functionality just be provided by the
** application that links against the SQLite library.
*/
................................................................................

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated. 
*/
sqlite3_mutex *sqlite3_mutex_alloc(int idNotUsed){
  return (sqlite3_mutex*)sqlite3_mutex_alloc;
}

/*
** This routine deallocates a previously allocated mutex.
*/
void sqlite3_mutex_free(sqlite3_mutex *pNotUsed){}

................................................................................
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
void sqlite3_mutex_enter(sqlite3_mutex *pNotUsed){}
int sqlite3_mutex_try(sqlite3_mutex *pNotUsed){ return SQLITE_OK; }

/*
** The sqlite3_mutex_exit() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
void sqlite3_mutex_leave(sqlite3_mutex *pNotUsed){}












#if 0
/**************** Non-recursive Pthread Mutex Implementation *****************
**
** This implementation of mutexes is built using a version of pthreads that
** does not have native support for recursive mutexes.
*/
................................................................................
    p->nRef--;
    if( p->nRef<=0 ){
      pthread_mutex_unlock(&p->mainMutex);
    }
    pthread_mutex_unlock(&p->auxMutex);
  }
}











#endif /* non-recursive pthreads */

#endif /* !defined(SQLITE_MUTEX_APPDEF) */







|







 







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>
>
>
>
>
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>
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>
>
>







 







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>
>
>
>
>



8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
..
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
..
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
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78
79
80
81
82
83
84
85
86
87
88
89
90
...
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the C functions that implement mutexes for
** use by the SQLite core.
**
** $Id: mutex.c,v 1.5 2007/08/20 22:48:43 drh Exp $
*/

/*
** If SQLITE_MUTEX_APPDEF is defined, then this whole module is
** omitted and equivalent functionality just be provided by the
** application that links against the SQLite library.
*/
................................................................................

/*
** The sqlite3_mutex_alloc() routine allocates a new
** mutex and returns a pointer to it.  If it returns NULL
** that means that a mutex could not be allocated. 
*/
sqlite3_mutex *sqlite3_mutex_alloc(int idNotUsed){
  return (sqlite3_mutex*)8;
}

/*
** This routine deallocates a previously allocated mutex.
*/
void sqlite3_mutex_free(sqlite3_mutex *pNotUsed){}

................................................................................
** can enter.  If the same thread tries to enter any other kind of mutex
** more than once, the behavior is undefined.
*/
void sqlite3_mutex_enter(sqlite3_mutex *pNotUsed){}
int sqlite3_mutex_try(sqlite3_mutex *pNotUsed){ return SQLITE_OK; }

/*
** The sqlite3_mutex_leave() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
*/
void sqlite3_mutex_leave(sqlite3_mutex *pNotUsed){}

/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
int sqlite3_mutex_held(sqlite3_mutex *pNotUsed){
  return 1;
}
int sqlite3_mutex_notheld(sqlite3_mutex *pNotUsed){
  return 1;
}

#if 0
/**************** Non-recursive Pthread Mutex Implementation *****************
**
** This implementation of mutexes is built using a version of pthreads that
** does not have native support for recursive mutexes.
*/
................................................................................
    p->nRef--;
    if( p->nRef<=0 ){
      pthread_mutex_unlock(&p->mainMutex);
    }
    pthread_mutex_unlock(&p->auxMutex);
  }
}

/*
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routine are
** intended for use inside assert() statements.
*/
int sqlite3_mutex_held(sqlite3_mutex *pNotUsed){
  return 1;
}
int sqlite3_mutex_notheld(sqlite3_mutex *pNotUsed){
  return 1;
}
#endif /* non-recursive pthreads */

#endif /* !defined(SQLITE_MUTEX_APPDEF) */

Changes to src/os.c.

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    return 0;
  }
  int sqlite3OsLockState(sqlite3_file *id){
    return id->pMethods->xLockState(id);
  }
#endif





int sqlite3OsOpen(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  sqlite3_file *pFile, 
  int flags, 
  int *pFlagsOut
){
#if defined(SQLITE_TEST) && !defined(SQLITE_OMIT_DISKIO)
  return sqlite3CrashFileOpen(pVfs, zPath, pFile, flags, pFlagsOut);
#endif
  return pVfs->xOpen(pVfs->pAppData, zPath, pFile, flags, pFlagsOut);
}
int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  return pVfs->xDelete(pVfs->pAppData, zPath, dirSync);
}
int sqlite3OsAccess(sqlite3_vfs *pVfs, const char *zPath, int flags){
  return pVfs->xAccess(pVfs->pAppData, zPath, flags);
................................................................................
}

/* 
** Default vfs implementation. Defined by the various os_X.c implementations.
*/
extern sqlite3_vfs sqlite3DefaultVfs;










sqlite3_vfs *sqlite3_find_vfs(const char *zVfs){
















  return &sqlite3DefaultVfs;
}








































































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    return 0;
  }
  int sqlite3OsLockState(sqlite3_file *id){
    return id->pMethods->xLockState(id);
  }
#endif

/*
** The next group of routines are convenience wrappers around the
** VFS methods.
*/
int sqlite3OsOpen(
  sqlite3_vfs *pVfs, 
  const char *zPath, 
  sqlite3_file *pFile, 
  int flags, 
  int *pFlagsOut
){



  return pVfs->xOpen(pVfs->pAppData, zPath, pFile, flags, pFlagsOut);
}
int sqlite3OsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
  return pVfs->xDelete(pVfs->pAppData, zPath, dirSync);
}
int sqlite3OsAccess(sqlite3_vfs *pVfs, const char *zPath, int flags){
  return pVfs->xAccess(pVfs->pAppData, zPath, flags);
................................................................................
}

/* 
** Default vfs implementation. Defined by the various os_X.c implementations.
*/
extern sqlite3_vfs sqlite3DefaultVfs;

/*
** The list of all registered VFS implementations.
*/
static sqlite3_vfs *vfsList = &sqlite3DefaultVfs;

/*
** Locate a VFS by name.  If no name is given, simply return the
** first VFS on the list.
*/
sqlite3_vfs *sqlite3_vfs_find(const char *zVfs){
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_vfs *pVfs;
  sqlite3_mutex_enter(mutex);
  for(pVfs = vfsList; pVfs; pVfs=pVfs->pNext){
    if( zVfs==0 ) break;
    if( strcmp(zVfs, pVfs->zName)==0 ) break;
  }
  if( pVfs ){
    pVfs->nRef++;
    assert( pVfs->nRef==1 || pVfs->vfsMutex!=0 );
    assert( pVfs->nRef>1 || pVfs->vfsMutex==0 );
    if( pVfs->vfsMutex==0 ){
      pVfs->vfsMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
    }
  }
  sqlite3_mutex_leave(mutex);
  return pVfs;
}

/*
** Release a VFS once it is no longer needed.
*/
int sqlite3_vfs_release(sqlite3_vfs *pVfs){
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  assert( pVfs->nRef>0 );
  pVfs->nRef--;
  if( pVfs->nRef==0 ){
    sqlite3_mutex_free(pVfs->vfsMutex);
    pVfs->vfsMutex = 0;
  }
  sqlite3_mutex_leave(mutex);
  return SQLITE_OK;
}

/*
** Unlink a VFS from the linked list
*/
static void vfsUnlink(sqlite3_vfs *pVfs){
  assert( sqlite3_mutex_held(sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER)) );
  if( vfsList==pVfs ){
    vfsList = pVfs->pNext;
  }else{
    sqlite3_vfs *p = vfsList;
    while( p->pNext && p->pNext!=pVfs ){
      p = p->pNext;
    }
    if( p->pNext==pVfs ){
      p->pNext = pVfs->pNext;
    }
  }
}

/*
** Register a VFS with the system.  It is harmless to register the same
** VFS multiple times.  The new VFS becomes the default if makeDflt is
** true.
*/
int sqlite3_vfs_register(sqlite3_vfs *pVfs, int makeDflt){
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  if( makeDflt || vfsList==0 ){
    pVfs->pNext = vfsList;
    vfsList = pVfs;
  }else{
    pVfs->pNext = vfsList->pNext;
    pVfs->pNext = pVfs;
  }
  sqlite3_mutex_leave(mutex);
  return SQLITE_OK;
}

/*
** Unregister a VFS so that it is no longer accessible.
*/
int sqlite3_vfs_unregister(sqlite3_vfs *pVfs){
  sqlite3_mutex *mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_MASTER);
  sqlite3_mutex_enter(mutex);
  vfsUnlink(pVfs);
  sqlite3_mutex_leave(mutex);
  return SQLITE_OK;
}

Changes to src/os_os2.h.

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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

/*
** Macros used to determine whether or not to use threads.  The
** SQLITE_UNIX_THREADS macro is defined if we are synchronizing for
** Posix threads and SQLITE_W32_THREADS is defined if we are
** synchronizing using Win32 threads.
*/
/* this mutex implementation only available with EMX */
#if defined(THREADSAFE) && THREADSAFE
# include <sys/builtin.h>
# include <sys/smutex.h>
# define SQLITE_OS2_THREADS 1
#endif

/*
** The OsFile structure is a operating-system independing representation







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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

/*
** Macros used to determine whether or not to use threads.  The
** SQLITE_OS2_THREADS macro is defined if we are synchronizing for
** Posix threads and SQLITE_W32_THREADS is defined if we are
** synchronizing using Win32 threads.
*/
/* this mutex implementation only available with EMX */
#if SQLITE_THREADSAFE
# include <sys/builtin.h>
# include <sys/smutex.h>
# define SQLITE_OS2_THREADS 1
#endif

/*
** The OsFile structure is a operating-system independing representation

Changes to src/os_unix.c.

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#include <sys/mount.h>
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
*/
#ifndef THREADSAFE
# define THREADSAFE 1
#endif
#if THREADSAFE
# include <pthread.h>
# define SQLITE_UNIX_THREADS 1
#endif

/*
** Default permissions when creating a new file
*/
................................................................................
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  unsigned char isOpen;     /* True if needs to be closed */
  int dirfd;                /* File descriptor for the directory */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;            /* The thread that "owns" this unixFile */
#endif
};

/*
** Include code that is common to all os_*.c files
*/
................................................................................
# define fcntl(A,B,C) 0
#endif

/*
** The threadid macro resolves to the thread-id or to 0.  Used for
** testing and debugging only.
*/
#ifdef SQLITE_UNIX_THREADS
#define threadid pthread_self()
#else
#define threadid 0
#endif

/*
** Set or check the unixFile.tid field.  This field is set when an unixFile
................................................................................
** Version 3.3.1 (2006-01-15):  unixFile can be moved from one thread to
** another as long as we are running on a system that supports threads
** overriding each others locks (which now the most common behavior)
** or if no locks are held.  But the unixFile.pLock field needs to be
** recomputed because its key includes the thread-id.  See the 
** transferOwnership() function below for additional information
*/
#if defined(SQLITE_UNIX_THREADS)
# define SET_THREADID(X)   (X)->tid = pthread_self()
# define CHECK_THREADID(X) (threadsOverrideEachOthersLocks==0 && \
                            !pthread_equal((X)->tid, pthread_self()))
#else
# define SET_THREADID(X)
# define CHECK_THREADID(X) 0
#endif
................................................................................
** lockKey.tid field to the thread ID.  If threads can override
** each others locks then tid is always set to zero.  tid is omitted
** if we compile without threading support.
*/
struct lockKey {
  dev_t dev;       /* Device number */
  ino_t ino;       /* Inode number */
#ifdef SQLITE_UNIX_THREADS
  pthread_t tid;   /* Thread ID or zero if threads can override each other */
#endif
};

/*
** An instance of the following structure is allocated for each open
** inode on each thread with a different process ID.  (Threads have
................................................................................
static void enterMutex(){
  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}
static void leaveMutex(){
  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}

#ifdef SQLITE_UNIX_THREADS
/*
** This variable records whether or not threads can override each others
** locks.
**
**    0:  No.  Threads cannot override each others locks.
**    1:  Yes.  Threads can override each others locks.
**   -1:  We don't know yet.
................................................................................
  pthread_create(&t[0], 0, threadLockingTest, &d[0]);
  pthread_create(&t[1], 0, threadLockingTest, &d[1]);
  pthread_join(t[0], 0);
  pthread_join(t[1], 0);
  close(fd);
  threadsOverrideEachOthersLocks =  d[0].result==0 && d[1].result==0;
}
#endif /* SQLITE_UNIX_THREADS */

/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pLock){
  if (pLock == NULL)
    return;
................................................................................
  struct openCnt *pOpen;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ) return 1;

  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
  key1.ino = statbuf.st_ino;
#ifdef SQLITE_UNIX_THREADS
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
  key1.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self();
#endif
  memset(&key2, 0, sizeof(key2));
  key2.dev = statbuf.st_dev;
................................................................................
** unable to override locks created by a different thread.  RedHat9 is
** an example of such a system.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE.  SQLITE_OK is returned if everything works.
*/
#ifdef SQLITE_UNIX_THREADS
static int transferOwnership(unixFile *pFile){
  int rc;
  pthread_t hSelf;
  if( threadsOverrideEachOthersLocks ){
    /* Ownership transfers not needed on this system */
    return SQLITE_OK;
  }
................................................................................
sqlite3_vfs sqlite3DefaultVfs = {
  1,                  /* iVersion */
  sizeof(unixFile),   /* szOsFile */
  MAX_PATHNAME,       /* mxPathname */
  0,                  /* nRef */
  0,                  /* vfsMutex */
  0,                  /* pNext */
  0,                  /* pPrev */
  "unix",             /* zName */
  0,                  /* pAppData */

  unixOpen,           /* xOpen */
  unixDelete,         /* xDelete */
  unixAccess,         /* xAccess */
  unixGetTempName,    /* xGetTempName */







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#include <sys/mount.h>
#endif /* SQLITE_ENABLE_LOCKING_STYLE */

/*
** If we are to be thread-safe, include the pthreads header and define
** the SQLITE_UNIX_THREADS macro.
*/



#if SQLITE_THREADSAFE
# include <pthread.h>
# define SQLITE_UNIX_THREADS 1
#endif

/*
** Default permissions when creating a new file
*/
................................................................................
#ifdef SQLITE_ENABLE_LOCKING_STYLE
  void *lockingContext;     /* Locking style specific state */
#endif /* SQLITE_ENABLE_LOCKING_STYLE */
  int h;                    /* The file descriptor */
  unsigned char locktype;   /* The type of lock held on this fd */
  unsigned char isOpen;     /* True if needs to be closed */
  int dirfd;                /* File descriptor for the directory */
#if SQLITE_THREADSAFE
  pthread_t tid;            /* The thread that "owns" this unixFile */
#endif
};

/*
** Include code that is common to all os_*.c files
*/
................................................................................
# define fcntl(A,B,C) 0
#endif

/*
** The threadid macro resolves to the thread-id or to 0.  Used for
** testing and debugging only.
*/
#if SQLITE_THREADSAFE
#define threadid pthread_self()
#else
#define threadid 0
#endif

/*
** Set or check the unixFile.tid field.  This field is set when an unixFile
................................................................................
** Version 3.3.1 (2006-01-15):  unixFile can be moved from one thread to
** another as long as we are running on a system that supports threads
** overriding each others locks (which now the most common behavior)
** or if no locks are held.  But the unixFile.pLock field needs to be
** recomputed because its key includes the thread-id.  See the 
** transferOwnership() function below for additional information
*/
#if SQLITE_THREADSAFE
# define SET_THREADID(X)   (X)->tid = pthread_self()
# define CHECK_THREADID(X) (threadsOverrideEachOthersLocks==0 && \
                            !pthread_equal((X)->tid, pthread_self()))
#else
# define SET_THREADID(X)
# define CHECK_THREADID(X) 0
#endif
................................................................................
** lockKey.tid field to the thread ID.  If threads can override
** each others locks then tid is always set to zero.  tid is omitted
** if we compile without threading support.
*/
struct lockKey {
  dev_t dev;       /* Device number */
  ino_t ino;       /* Inode number */
#if SQLITE_THREADSAFE
  pthread_t tid;   /* Thread ID or zero if threads can override each other */
#endif
};

/*
** An instance of the following structure is allocated for each open
** inode on each thread with a different process ID.  (Threads have
................................................................................
static void enterMutex(){
  sqlite3_mutex_enter(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}
static void leaveMutex(){
  sqlite3_mutex_leave(sqlite3_mutex_alloc(SQLITE_MUTEX_GLOBAL));
}

#if SQLITE_THREADSAFE
/*
** This variable records whether or not threads can override each others
** locks.
**
**    0:  No.  Threads cannot override each others locks.
**    1:  Yes.  Threads can override each others locks.
**   -1:  We don't know yet.
................................................................................
  pthread_create(&t[0], 0, threadLockingTest, &d[0]);
  pthread_create(&t[1], 0, threadLockingTest, &d[1]);
  pthread_join(t[0], 0);
  pthread_join(t[1], 0);
  close(fd);
  threadsOverrideEachOthersLocks =  d[0].result==0 && d[1].result==0;
}
#endif /* SQLITE_THREADSAFE */

/*
** Release a lockInfo structure previously allocated by findLockInfo().
*/
static void releaseLockInfo(struct lockInfo *pLock){
  if (pLock == NULL)
    return;
................................................................................
  struct openCnt *pOpen;
  rc = fstat(fd, &statbuf);
  if( rc!=0 ) return 1;

  memset(&key1, 0, sizeof(key1));
  key1.dev = statbuf.st_dev;
  key1.ino = statbuf.st_ino;
#if SQLITE_THREADSAFE
  if( threadsOverrideEachOthersLocks<0 ){
    testThreadLockingBehavior(fd);
  }
  key1.tid = threadsOverrideEachOthersLocks ? 0 : pthread_self();
#endif
  memset(&key2, 0, sizeof(key2));
  key2.dev = statbuf.st_dev;
................................................................................
** unable to override locks created by a different thread.  RedHat9 is
** an example of such a system.
**
** Ownership transfer is only allowed if the unixFile is currently unlocked.
** If the unixFile is locked and an ownership is wrong, then return
** SQLITE_MISUSE.  SQLITE_OK is returned if everything works.
*/
#if SQLITE_THREADSAFE
static int transferOwnership(unixFile *pFile){
  int rc;
  pthread_t hSelf;
  if( threadsOverrideEachOthersLocks ){
    /* Ownership transfers not needed on this system */
    return SQLITE_OK;
  }
................................................................................
sqlite3_vfs sqlite3DefaultVfs = {
  1,                  /* iVersion */
  sizeof(unixFile),   /* szOsFile */
  MAX_PATHNAME,       /* mxPathname */
  0,                  /* nRef */
  0,                  /* vfsMutex */
  0,                  /* pNext */

  "unix",             /* zName */
  0,                  /* pAppData */

  unixOpen,           /* xOpen */
  unixDelete,         /* xDelete */
  unixAccess,         /* xAccess */
  unixGetTempName,    /* xGetTempName */

Changes to src/random.c.

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*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
**
** $Id: random.c,v 1.17 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"


/*
** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
................................................................................
  ** number generator) not as an encryption device.
  */
  if( !prng.isInit ){
    int i;
    char k[256];
    prng.j = 0;
    prng.i = 0;
    sqlite3OsRandomness(sqlite3_find_vfs(0), 256, k);
    for(i=0; i<256; i++){
      prng.s[i] = i;
    }
    for(i=0; i<256; i++){
      prng.j += prng.s[i] + k[i];
      t = prng.s[prng.j];
      prng.s[prng.j] = prng.s[i];







|







 







|







11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
..
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
*************************************************************************
** This file contains code to implement a pseudo-random number
** generator (PRNG) for SQLite.
**
** Random numbers are used by some of the database backends in order
** to generate random integer keys for tables or random filenames.
**
** $Id: random.c,v 1.18 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"


/*
** Get a single 8-bit random value from the RC4 PRNG.  The Mutex
................................................................................
  ** number generator) not as an encryption device.
  */
  if( !prng.isInit ){
    int i;
    char k[256];
    prng.j = 0;
    prng.i = 0;
    sqlite3OsRandomness(sqlite3_vfs_find(0), 256, k);
    for(i=0; i<256; i++){
      prng.s[i] = i;
    }
    for(i=0; i<256; i++){
      prng.j += prng.s[i] + k[i];
      t = prng.s[prng.j];
      prng.s[prng.j] = prng.s[i];

Changes to src/sqlite.h.in.

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3276
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3282
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** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.230 2007/08/18 10:59:21 danielk1977 Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
** last user closes.  In other words, vfsMutex will be allocated
** when nRef transitions from 0 to 1 and will be deallocated when
** nRef transitions from 1 to 0.
**
** Registered vfs modules are kept on a linked list formed by
** the pNext and pPrev pointers.  The [sqlite3_register_vfs()]
** and [sqlite3_unregister_vfs()] interfaces manage this list
** in a thread-safe way.  The [sqlite3_find_vfs()] searches the
** list.
**
** The zName field holds the name of the VFS module.  The name must
** be unique across all VFS modules.
**
** SQLite will guarantee that the zFilename string passed to
** xOpen() is a full pathname as generated by xFullPathname() and
................................................................................
struct sqlite3_vfs {
  int iVersion;            /* Structure version number */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  int nRef;                /* Number of references to this structure */
  sqlite3_mutex *vfsMutex; /* A mutex for this VFS */
  sqlite3_vfs *pNext;      /* Next registered VFS */
  sqlite3_vfs *pPrev;      /* Previous registered VFS */
  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Application context */
  int (*xOpen)(void *pAppData, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(void *pAppData, const char *zName, int syncDir);
  int (*xAccess)(void *pAppData, const char *zName, int flags);
  int (*xGetTempName)(void *pAppData, char *zOut);
................................................................................
** data structures out from under the executing query and will 
** probably result in a segmentation fault or other runtime error.
**
** There can only be a single busy handler defined for each database
** connection.  Setting a new busy handler clears any previous one.
** Note that calling [sqlite3_busy_timeout()] will also set or clear
** the busy handler.







*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout
**
** This routine sets a busy handler that sleeps for a while when a
................................................................................
** A virtual filesystem (VFS) is an [sqlite3_vfs] object
** that SQLite uses to interact
** with the underlying operating system.  Most builds come with a
** single default VFS that is appropriate for the host computer.
** New VFSes can be registered and existing VFSes can be unregistered.
** The following interfaces are provided.
**
** The sqlite3_find_vfs() interface returns a pointer to a VFS given its
** name.  Names are case sensitive.  If there is no match, a NULL
** pointer is returned.  If zVfsName is NULL then the default 
** VFS is returned.



**
** New VFSes are registered with sqlite3_register_vfs().  Each
** new VFS becomes the default VFS if the makeDflt flag is set.
** The same VFS can be registered multiple times without injury.
** To make an existing VFS into the default VFS, register it again
** with the makeDflt flag set.
** 
** Unregister a VFS with the sqlite3_unregister_vfs() interface.
** If the default VFS is unregistered, another VFS is chosen as
** the default.  The choice for the new VFS is arbitrary.
*/
sqlite3_vfs *sqlite3_find_vfs(const char *zVfsName);

int sqlite3_register_vfs(sqlite3_vfs*, int makeDflt);
int sqlite3_unregister_vfs(sqlite3_vfs*);

/*
** CAPI3REF: Mutexes
**
** The SQLite core uses these routines for thread
** synchronization.  Though they are intended for internal
** use by SQLite, code that links against SQLite is
................................................................................
** more than once, the behavior is undefined.   SQLite will never exhibit
** such behavior in its own use of mutexes.
**
** The sqlite3_mutex_exit() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.



















*/
sqlite3_mutex *sqlite3_mutex_alloc(int);
void sqlite3_mutex_free(sqlite3_mutex*);
void sqlite3_mutex_enter(sqlite3_mutex*);
int sqlite3_mutex_try(sqlite3_mutex*);
void sqlite3_mutex_leave(sqlite3_mutex*);


#define SQLITE_MUTEX_FAST             0
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3
#define SQLITE_MUTEX_STATIC_PRNG      4









|







 







|







 







<







 







>
>
>
>
>
>
>







 







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>

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>
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|







 







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869
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....
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....
3279
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3313
3314
3315
3316
3317
3318
3319
** on how SQLite interfaces are suppose to operate.
**
** The name of this file under configuration management is "sqlite.h.in".
** The makefile makes some minor changes to this file (such as inserting
** the version number) and changes its name to "sqlite3.h" as
** part of the build process.
**
** @(#) $Id: sqlite.h.in,v 1.231 2007/08/20 22:48:43 drh Exp $
*/
#ifndef _SQLITE3_H_
#define _SQLITE3_H_
#include <stdarg.h>     /* Needed for the definition of va_list */

/*
** Make sure we can call this stuff from C++.
................................................................................
** last user closes.  In other words, vfsMutex will be allocated
** when nRef transitions from 0 to 1 and will be deallocated when
** nRef transitions from 1 to 0.
**
** Registered vfs modules are kept on a linked list formed by
** the pNext and pPrev pointers.  The [sqlite3_register_vfs()]
** and [sqlite3_unregister_vfs()] interfaces manage this list
** in a thread-safe way.  The [sqlite3_acquire_vfs()] searches the
** list.
**
** The zName field holds the name of the VFS module.  The name must
** be unique across all VFS modules.
**
** SQLite will guarantee that the zFilename string passed to
** xOpen() is a full pathname as generated by xFullPathname() and
................................................................................
struct sqlite3_vfs {
  int iVersion;            /* Structure version number */
  int szOsFile;            /* Size of subclassed sqlite3_file */
  int mxPathname;          /* Maximum file pathname length */
  int nRef;                /* Number of references to this structure */
  sqlite3_mutex *vfsMutex; /* A mutex for this VFS */
  sqlite3_vfs *pNext;      /* Next registered VFS */

  const char *zName;       /* Name of this virtual file system */
  void *pAppData;          /* Application context */
  int (*xOpen)(void *pAppData, const char *zName, sqlite3_file*,
               int flags, int *pOutFlags);
  int (*xDelete)(void *pAppData, const char *zName, int syncDir);
  int (*xAccess)(void *pAppData, const char *zName, int flags);
  int (*xGetTempName)(void *pAppData, char *zOut);
................................................................................
** data structures out from under the executing query and will 
** probably result in a segmentation fault or other runtime error.
**
** There can only be a single busy handler defined for each database
** connection.  Setting a new busy handler clears any previous one.
** Note that calling [sqlite3_busy_timeout()] will also set or clear
** the busy handler.
**
** When operating in [sqlite3_enable_shared_cache | shared cache mode],
** only a single busy handler can be defined for each database file.
** So if two database connections share a single cache, then changing
** the busy handler on one connection will also change the busy
** handler in the other connection.  The busy handler is invoked
** in the thread that was running when the SQLITE_BUSY was hit.
*/
int sqlite3_busy_handler(sqlite3*, int(*)(void*,int), void*);

/*
** CAPI3REF: Set A Busy Timeout
**
** This routine sets a busy handler that sleeps for a while when a
................................................................................
** A virtual filesystem (VFS) is an [sqlite3_vfs] object
** that SQLite uses to interact
** with the underlying operating system.  Most builds come with a
** single default VFS that is appropriate for the host computer.
** New VFSes can be registered and existing VFSes can be unregistered.
** The following interfaces are provided.
**
** The sqlite3_vfs_find() interface returns a pointer to a VFS given its
** name.  Names are case sensitive.  If there is no match, a NULL
** pointer is returned.  If zVfsName is NULL then the default 
** VFS is returned.  If a valid VFS pointer is returned, its
** vfsMutex field will have been initialized and nRef will be
** greater than zero.  The sqlite3_vfs_release() function should
** be used to release the VFS when it is no longer needed.
**
** New VFSes are registered with sqlite3_vfs_register().  Each
** new VFS becomes the default VFS if the makeDflt flag is set.
** The same VFS can be registered multiple times without injury.
** To make an existing VFS into the default VFS, register it again
** with the makeDflt flag set.
** 
** Unregister a VFS with the sqlite3_vfs_unregister() interface.
** If the default VFS is unregistered, another VFS is chosen as
** the default.  The choice for the new VFS is arbitrary.
*/
sqlite3_vfs *sqlite3_vfs_find(const char *zVfsName);
int sqlite3_vfs_release(sqlite3_vfs*);
int sqlite3_vfs_register(sqlite3_vfs*, int makeDflt);
int sqlite3_vfs_unregister(sqlite3_vfs*);

/*
** CAPI3REF: Mutexes
**
** The SQLite core uses these routines for thread
** synchronization.  Though they are intended for internal
** use by SQLite, code that links against SQLite is
................................................................................
** more than once, the behavior is undefined.   SQLite will never exhibit
** such behavior in its own use of mutexes.
**
** The sqlite3_mutex_exit() routine exits a mutex that was
** previously entered by the same thread.  The behavior
** is undefined if the mutex is not currently entered or
** is not currently allocated.  SQLite will never do either.
**
** The sqlite3_mutex_held() and sqlite3_mutex_notheld() routines
** are intended for use inside assert() statements.  They should
** return true if the mutex in their argument is held or not held,
** respectively, by the current thread. The implementation is
** not required to provided working implementations of these
** routines as their intended use is within assert() statements
** only.  If the implementation does not provide working
** versions of these routines, it must at least provide stubs
** that always return true.
**
** If the argument to sqlite3_mutex_held() is a NULL pointer then
** the routine should return 1.  This seems counter-intuitive since
** clearly the mutex cannot be held if it does not exist.  But the
** the reason the mutex does not exist is because the build is not
** using mutexes.  And we do not want the assert() containing the
** call to sqlite3_mutex_held() to fail, so a non-zero return is
** the appropriate thing to do.  The sqlite3_mutex_notheld() 
** interface should also return 1 when given a NULL pointer.
*/
sqlite3_mutex *sqlite3_mutex_alloc(int);
void sqlite3_mutex_free(sqlite3_mutex*);
void sqlite3_mutex_enter(sqlite3_mutex*);
int sqlite3_mutex_try(sqlite3_mutex*);
void sqlite3_mutex_leave(sqlite3_mutex*);
int sqlite3_mutex_held(sqlite3_mutex*);
int sqlite3_mutex_notheld(sqlite3_mutex*);
#define SQLITE_MUTEX_FAST             0
#define SQLITE_MUTEX_RECURSIVE        1
#define SQLITE_MUTEX_STATIC_MASTER    2
#define SQLITE_MUTEX_STATIC_MEM       3
#define SQLITE_MUTEX_STATIC_PRNG      4


Changes to src/sqliteInt.h.

7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
..
29
30
31
32
33
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35













36
37
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39
40
41
42
...
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
....
1814
1815
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1817
1818
1819
1820
1821


1822




1823
1824

1825
1826
1827
1828
1829
1830
1831
....
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
**    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 1.592 2007/08/20 14:23:44 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
#include "sqliteLimit.h"


#if defined(SQLITE_TCL) || defined(TCLSH)
................................................................................
** option is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
** feature.
*/
#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
# define NDEBUG 1
#endif














/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
** large file support, or if the OS is windows, these should be no-ops.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line.  This is necessary if you are compiling
................................................................................
  int nTable;                   /* Number of tables in the database */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 priorNewRowid;            /* Last randomly generated ROWID */
  int magic;                    /* Magic number for detect library misuse */
  int nChange;                  /* Value returned by sqlite3_changes() */
  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
  sqlite3_mutex *pMutex;        /* Connection mutex */
  struct sqlite3InitInfo {      /* Information used during initialization */
    int iDb;                    /* When back is being initialized */
    int newTnum;                /* Rootpage of table being initialized */
    u8 busy;                    /* TRUE if currently initializing */
  } init;
  int nExtension;               /* Number of loaded extensions */
  void **aExtension;            /* Array of shared libraray handles */
................................................................................
#endif

#ifdef SQLITE_TEST
  int sqlite3Utf8To8(unsigned char*);
#endif

/*
** FIX ME:  create these routines


*/




#define sqlite3MallocDisallow()
#define sqlite3MallocAllow()



#ifdef SQLITE_OMIT_VIRTUALTABLE
#  define sqlite3VtabClear(X)
#  define sqlite3VtabSync(X,Y) (Y)
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
................................................................................
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
int sqlite3Reprepare(Vdbe*);
void sqlite3ExprListCheckLength(Parse*, ExprList*, int, const char*);
CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);
int sqlite3CrashFileOpen(sqlite3_vfs*, const char*, sqlite3_file*, int,int*);

#if SQLITE_MAX_EXPR_DEPTH>0
  void sqlite3ExprSetHeight(Expr *);
  int sqlite3SelectExprHeight(Select *);
#else
  #define sqlite3ExprSetHeight(x)
#endif







|







 







>
>
>
>
>
>
>
>
>
>
>
>
>







 







|







 







|
>
>

>
>
>
>
|
|
>







 







<







7
8
9
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12
13
14
15
16
17
18
19
20
21
..
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
...
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
....
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
....
1866
1867
1868
1869
1870
1871
1872

1873
1874
1875
1876
1877
1878
1879
**    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 1.593 2007/08/20 22:48:43 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
#include "sqliteLimit.h"


#if defined(SQLITE_TCL) || defined(TCLSH)
................................................................................
** option is set.  Thus NDEBUG becomes an opt-in rather than an opt-out
** feature.
*/
#if !defined(NDEBUG) && !defined(SQLITE_DEBUG) 
# define NDEBUG 1
#endif

/*
** The SQLITE_THREADSAFE macro must be defined as either 0 or 1.
** Older versions of SQLite used an optional THREADSAFE macro.
** We support that for legacy
*/
#if !defined(SQLITE_THREADSAFE)
#if defined(THREADSAFE)
# define SQLITE_THREADSAFE THREADSAFE
#else
# define SQLTIE_THREADSAFE 1
#endif
#endif

/*
** These #defines should enable >2GB file support on Posix if the
** underlying operating system supports it.  If the OS lacks
** large file support, or if the OS is windows, these should be no-ops.
**
** Large file support can be disabled using the -DSQLITE_DISABLE_LFS switch
** on the compiler command line.  This is necessary if you are compiling
................................................................................
  int nTable;                   /* Number of tables in the database */
  CollSeq *pDfltColl;           /* The default collating sequence (BINARY) */
  i64 lastRowid;                /* ROWID of most recent insert (see above) */
  i64 priorNewRowid;            /* Last randomly generated ROWID */
  int magic;                    /* Magic number for detect library misuse */
  int nChange;                  /* Value returned by sqlite3_changes() */
  int nTotalChange;             /* Value returned by sqlite3_total_changes() */
  sqlite3_mutex *mutex;         /* Connection mutex */
  struct sqlite3InitInfo {      /* Information used during initialization */
    int iDb;                    /* When back is being initialized */
    int newTnum;                /* Rootpage of table being initialized */
    u8 busy;                    /* TRUE if currently initializing */
  } init;
  int nExtension;               /* Number of loaded extensions */
  void **aExtension;            /* Array of shared libraray handles */
................................................................................
#endif

#ifdef SQLITE_TEST
  int sqlite3Utf8To8(unsigned char*);
#endif

/*
** The MallocDisallow() and MallocAllow() routines are like asserts.
** Call them around a section of code that you do not expect to do
** any memory allocation.
*/
#ifdef SQLITE_MEMDEBUG
  void sqlite3MallocDisallow(void);
  void sqlite3MallocAllow(void);
#else
# define sqlite3MallocDisallow()
# define sqlite3MallocAllow()
#endif


#ifdef SQLITE_OMIT_VIRTUALTABLE
#  define sqlite3VtabClear(X)
#  define sqlite3VtabSync(X,Y) (Y)
#  define sqlite3VtabRollback(X)
#  define sqlite3VtabCommit(X)
................................................................................
int sqlite3VtabCallDestroy(sqlite3*, int, const char *);
int sqlite3VtabBegin(sqlite3 *, sqlite3_vtab *);
FuncDef *sqlite3VtabOverloadFunction(sqlite3 *,FuncDef*, int nArg, Expr*);
void sqlite3InvalidFunction(sqlite3_context*,int,sqlite3_value**);
int sqlite3Reprepare(Vdbe*);
void sqlite3ExprListCheckLength(Parse*, ExprList*, int, const char*);
CollSeq *sqlite3BinaryCompareCollSeq(Parse *, Expr *, Expr *);


#if SQLITE_MAX_EXPR_DEPTH>0
  void sqlite3ExprSetHeight(Expr *);
  int sqlite3SelectExprHeight(Select *);
#else
  #define sqlite3ExprSetHeight(x)
#endif

Changes to src/test1.c.

9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
....
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
....
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.264 2007/08/17 15:53:37 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
  extern int sqlite3_memMax;
  extern int sqlite3_like_count;
  extern int sqlite3_xferopt_count;
  extern int sqlite3_pager_readdb_count;
  extern int sqlite3_pager_writedb_count;
  extern int sqlite3_pager_writej_count;
  extern int sqlite3_pager_pgfree_count;
#if OS_UNIX && defined(SQLITE_TEST) && defined(THREADSAFE) && THREADSAFE
  extern int threadsOverrideEachOthersLocks;
#endif
#if OS_WIN
  extern int sqlite3_os_type;
#endif
#ifdef SQLITE_DEBUG
  extern int sqlite3_os_trace;
................................................................................
      (char*)&sqlite3_pager_writej_count, TCL_LINK_INT);
  Tcl_LinkVar(interp, "sqlite3_pager_pgfree_count",
      (char*)&sqlite3_pager_pgfree_count, TCL_LINK_INT);
#ifndef SQLITE_OMIT_UTF16
  Tcl_LinkVar(interp, "unaligned_string_counter",
      (char*)&unaligned_string_counter, TCL_LINK_INT);
#endif
#if OS_UNIX && defined(SQLITE_TEST) && defined(THREADSAFE) && THREADSAFE
  Tcl_LinkVar(interp, "threadsOverrideEachOthersLocks",
      (char*)&threadsOverrideEachOthersLocks, TCL_LINK_INT);
#endif
#ifndef SQLITE_OMIT_UTF16
  Tcl_LinkVar(interp, "sqlite_last_needed_collation",
      (char*)&pzNeededCollation, TCL_LINK_STRING|TCL_LINK_READ_ONLY);
#endif







|







 







|







 







|







9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
....
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
....
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing all sorts of SQLite interfaces.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.265 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................
  extern int sqlite3_memMax;
  extern int sqlite3_like_count;
  extern int sqlite3_xferopt_count;
  extern int sqlite3_pager_readdb_count;
  extern int sqlite3_pager_writedb_count;
  extern int sqlite3_pager_writej_count;
  extern int sqlite3_pager_pgfree_count;
#if OS_UNIX && defined(SQLITE_TEST) && SQLITE_THREADSAFE
  extern int threadsOverrideEachOthersLocks;
#endif
#if OS_WIN
  extern int sqlite3_os_type;
#endif
#ifdef SQLITE_DEBUG
  extern int sqlite3_os_trace;
................................................................................
      (char*)&sqlite3_pager_writej_count, TCL_LINK_INT);
  Tcl_LinkVar(interp, "sqlite3_pager_pgfree_count",
      (char*)&sqlite3_pager_pgfree_count, TCL_LINK_INT);
#ifndef SQLITE_OMIT_UTF16
  Tcl_LinkVar(interp, "unaligned_string_counter",
      (char*)&unaligned_string_counter, TCL_LINK_INT);
#endif
#if OS_UNIX && defined(SQLITE_TEST) && SQLITE_THREADSAFE
  Tcl_LinkVar(interp, "threadsOverrideEachOthersLocks",
      (char*)&threadsOverrideEachOthersLocks, TCL_LINK_INT);
#endif
#ifndef SQLITE_OMIT_UTF16
  Tcl_LinkVar(interp, "sqlite_last_needed_collation",
      (char*)&pzNeededCollation, TCL_LINK_STRING|TCL_LINK_READ_ONLY);
#endif

Changes to src/test2.c.

9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
..
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
...
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.48 2007/08/20 14:23:44 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  char zBuf[100];
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " FILENAME N-PAGE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &nPage) ) return TCL_ERROR;
  rc = sqlite3PagerOpen(sqlite3_find_vfs(0), &pPager, argv[1], 0, 0);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, errorName(rc), 0);
    return TCL_ERROR;
  }
  sqlite3PagerSetCachesize(pPager, nPage);
  sqlite3PagerSetPagesize(pPager, test_pagesize);
  sqlite3_snprintf(sizeof(zBuf),zBuf,"%p",pPager);
................................................................................
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " N-MEGABYTES FILE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], &n) ) return TCL_ERROR;

  pVfs = sqlite3_find_vfs(0);
  rc = sqlite3OsOpenMalloc(pVfs, argv[2], &fd, 
      (SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_DB), 0
  );
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }







|







 







|







 







|







9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
..
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
...
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the pager.c module in SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test2.c,v 1.49 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include "tcl.h"
#include <stdlib.h>
#include <string.h>
................................................................................
  char zBuf[100];
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " FILENAME N-PAGE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[2], &nPage) ) return TCL_ERROR;
  rc = sqlite3PagerOpen(sqlite3_vfs_find(0), &pPager, argv[1], 0, 0);
  if( rc!=SQLITE_OK ){
    Tcl_AppendResult(interp, errorName(rc), 0);
    return TCL_ERROR;
  }
  sqlite3PagerSetCachesize(pPager, nPage);
  sqlite3PagerSetPagesize(pPager, test_pagesize);
  sqlite3_snprintf(sizeof(zBuf),zBuf,"%p",pPager);
................................................................................
  if( argc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
       " N-MEGABYTES FILE\"", 0);
    return TCL_ERROR;
  }
  if( Tcl_GetInt(interp, argv[1], &n) ) return TCL_ERROR;

  pVfs = sqlite3_vfs_find(0);
  rc = sqlite3OsOpenMalloc(pVfs, argv[2], &fd, 
      (SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_DB), 0
  );
  if( rc ){
    Tcl_AppendResult(interp, "open failed: ", errorName(rc), 0);
    return TCL_ERROR;
  }

Changes to src/test4.c.

7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
**    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 testing the the SQLite library in a multithreaded environment.
**
** $Id: test4.c,v 1.18 2007/08/16 04:30:40 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#if defined(OS_UNIX) && OS_UNIX==1 && defined(THREADSAFE) && THREADSAFE==1
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <ctype.h>

/*







|




|







7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
**    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 testing the the SQLite library in a multithreaded environment.
**
** $Id: test4.c,v 1.19 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#if defined(OS_UNIX) && OS_UNIX==1 && SQLITE_THREADSAFE
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <ctype.h>

/*

Changes to src/test6.c.

447
448
449
450
451
452
453








454
455
456
457
458
459
460
461
462
463
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465
466
467
468
469
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...
495
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501

502
503
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508
509
...
524
525
526
527
528
529
530
531
532
533
534
535
















536
537
538
539
540
541
542
  cfCheckReservedLock,          /* xCheckReservedLock */
  cfBreakLock,                  /* xBreakLock */
  cfLockState,                  /* xLockState */
  cfSectorSize,                 /* xSectorSize */
  cfDeviceCharacteristics       /* xDeviceCharacteristics */
};









/*
** Open a crash-file file handle. The vfs pVfs is used to open
** the underlying real file.
**
** The caller will have allocated pVfs->szOsFile bytes of space
** at pFile. This file uses this space for the CrashFile structure
** and allocates space for the "real" file structure using 
** sqlite3_malloc(). The assumption here is (pVfs->szOsFile) is
** equal or greater than sizeof(CrashFile).
*/
int sqlite3CrashFileOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  int rc;
................................................................................
        rc = SQLITE_NOMEM;
      }
    }
    if( rc!=SQLITE_OK && pWrapper->pMethod ){
      sqlite3OsClose(pFile);
    }
  }else{

    rc = pVfs->xOpen(pVfs->pAppData, zName, pFile, flags, pOutFlags);
  }
  return rc;
}

/*
** tclcmd:   sqlite_crashparams ?OPTIONS? DELAY CRASHFILE
**
................................................................................
*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  sqlite3_vfs *pVfs;
  int i;
  int iDelay;
  const char *zCrashFile;
  int nCrashFile;

















  int iDc = 0;
  int iSectorSize = 0;
  int setSectorsize = 0;
  int setDeviceChar = 0;

  struct DeviceFlag {







>
>
>
>
>
>
>
>










|







 







>
|







 







<




>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>







447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
...
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
...
533
534
535
536
537
538
539

540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
  cfCheckReservedLock,          /* xCheckReservedLock */
  cfBreakLock,                  /* xBreakLock */
  cfLockState,                  /* xLockState */
  cfSectorSize,                 /* xSectorSize */
  cfDeviceCharacteristics       /* xDeviceCharacteristics */
};

/*
** Application data for the crash VFS
*/
struct crashAppData {
  int (*xOpen)(void*,const char*,sqlite3_file*,int,int*); /* Original xOpen */
  void *pAppData;                                      /* Original pAppData */
};

/*
** Open a crash-file file handle. The vfs pVfs is used to open
** the underlying real file.
**
** The caller will have allocated pVfs->szOsFile bytes of space
** at pFile. This file uses this space for the CrashFile structure
** and allocates space for the "real" file structure using 
** sqlite3_malloc(). The assumption here is (pVfs->szOsFile) is
** equal or greater than sizeof(CrashFile).
*/
static int sqlite3CrashFileOpen(
  sqlite3_vfs *pVfs,
  const char *zName,
  sqlite3_file *pFile,
  int flags,
  int *pOutFlags
){
  int rc;
................................................................................
        rc = SQLITE_NOMEM;
      }
    }
    if( rc!=SQLITE_OK && pWrapper->pMethod ){
      sqlite3OsClose(pFile);
    }
  }else{
    struct crashAppData *pData = (struct crashAppData*)pVfs->pAppData;
    rc = pData->xOpen(pData->pAppData, zName, pFile, flags, pOutFlags);
  }
  return rc;
}

/*
** tclcmd:   sqlite_crashparams ?OPTIONS? DELAY CRASHFILE
**
................................................................................
*/
static int crashParamsObjCmd(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){

  int i;
  int iDelay;
  const char *zCrashFile;
  int nCrashFile;
  static sqlite3_vfs crashVfs, *pOriginalVfs;
  static struct crashAppData appData;

  if( pOriginalVfs==0 ){
    pOriginalVfs = sqlite3_vfs_find(0);
    crashVfs = *pOriginalVfs;
    crashVfs.xOpen = sqlite3CrashFileOpen;
    crashVfs.vfsMutex = 0;
    crashVfs.nRef = 0;
    crashVfs.pAppData = &appData;
    appData.xOpen = pOriginalVfs->xOpen;
    appData.pAppData = pOriginalVfs->pAppData;
    sqlite3_vfs_release(pOriginalVfs);
    sqlite3_vfs_unregister(pOriginalVfs);
    sqlite3_vfs_register(&crashVfs, 1);
  }

  int iDc = 0;
  int iSectorSize = 0;
  int setSectorsize = 0;
  int setDeviceChar = 0;

  struct DeviceFlag {

Changes to src/test7.c.

8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the client/server version of the SQLite library.
** Derived from test4.c.
**
** $Id: test7.c,v 1.5 2007/08/16 04:30:40 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"

/*
** This test only works on UNIX with a THREADSAFE build that includes
** the SQLITE_SERVER option.
*/
#if OS_UNIX && defined(THREADSAFE) && THREADSAFE==1 && \
    defined(SQLITE_SERVER) && !defined(SQLITE_OMIT_SHARED_CACHE)

#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <ctype.h>







|






|


|







8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the client/server version of the SQLite library.
** Derived from test4.c.
**
** $Id: test7.c,v 1.6 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"

/*
** This test only works on UNIX with a SQLITE_THREADSAFE build that includes
** the SQLITE_SERVER option.
*/
#if OS_UNIX && SQLITE_THREADSAFE && \
    defined(SQLITE_SERVER) && !defined(SQLITE_OMIT_SHARED_CACHE)

#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <sched.h>
#include <ctype.h>

Changes to src/test_async.c.

70
71
72
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77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
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94
95
96
....
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
** when the buffer gets to be too big.
*/

#include "sqliteInt.h"
#include "os.h"
#include <tcl.h>

/* If the THREADSAFE macro is not set, assume that it is turned off. */
#ifndef THREADSAFE
# define THREADSAFE 0
#endif

/*
** This test uses pthreads and hence only works on unix and with
** a threadsafe build of SQLite.  It also requires that the redefinable
** I/O feature of SQLite be turned on.  This feature is turned off by
** default.  If a required element is missing, almost all of the code
** in this file is commented out.
*/
#if OS_UNIX && THREADSAFE && defined(SQLITE_ENABLE_REDEF_IO)

/*
** This demo uses pthreads.  If you do not have a pthreads implementation
** for your operating system, you will need to recode the threading 
** logic.
*/
#include <pthread.h>
................................................................................
  }else{
    ASYNC_TRACE(("NO-WAIT\n"));
  }
  return TCL_OK;
}


#endif  /* OS_UNIX and THREADSAFE and defined(SQLITE_ENABLE_REDEF_IO) */

/*
** This routine registers the custom TCL commands defined in this
** module.  This should be the only procedure visible from outside
** of this module.
*/
int Sqlitetestasync_Init(Tcl_Interp *interp){
#if OS_UNIX && THREADSAFE && defined(SQLITE_ENABLE_REDEF_IO)
  Tcl_CreateObjCommand(interp,"sqlite3async_enable",testAsyncEnable,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_halt",testAsyncHalt,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_delay",testAsyncDelay,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_start",testAsyncStart,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_wait",testAsyncWait,0,0);
  Tcl_LinkVar(interp, "sqlite3async_trace",
      (char*)&sqlite3async_trace, TCL_LINK_INT);
#endif  /* OS_UNIX and THREADSAFE and defined(SQLITE_ENABLE_REDEF_IO) */
  return TCL_OK;
}







<
<
<
<
<







|







 







|







|







|


70
71
72
73
74
75
76





77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
....
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
** when the buffer gets to be too big.
*/

#include "sqliteInt.h"
#include "os.h"
#include <tcl.h>






/*
** This test uses pthreads and hence only works on unix and with
** a threadsafe build of SQLite.  It also requires that the redefinable
** I/O feature of SQLite be turned on.  This feature is turned off by
** default.  If a required element is missing, almost all of the code
** in this file is commented out.
*/
#if OS_UNIX && SQLITE_THREADSAFE && defined(SQLITE_ENABLE_REDEF_IO)

/*
** This demo uses pthreads.  If you do not have a pthreads implementation
** for your operating system, you will need to recode the threading 
** logic.
*/
#include <pthread.h>
................................................................................
  }else{
    ASYNC_TRACE(("NO-WAIT\n"));
  }
  return TCL_OK;
}


#endif  /* OS_UNIX and SQLITE_THREADSAFE and defined(SQLITE_ENABLE_REDEF_IO) */

/*
** This routine registers the custom TCL commands defined in this
** module.  This should be the only procedure visible from outside
** of this module.
*/
int Sqlitetestasync_Init(Tcl_Interp *interp){
#if OS_UNIX && SQLITE_THREADSAFE && defined(SQLITE_ENABLE_REDEF_IO)
  Tcl_CreateObjCommand(interp,"sqlite3async_enable",testAsyncEnable,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_halt",testAsyncHalt,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_delay",testAsyncDelay,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_start",testAsyncStart,0,0);
  Tcl_CreateObjCommand(interp,"sqlite3async_wait",testAsyncWait,0,0);
  Tcl_LinkVar(interp, "sqlite3async_trace",
      (char*)&sqlite3async_trace, TCL_LINK_INT);
#endif  /* OS_UNIX and SQLITE_THREADSAFE and defined(SQLITE_ENABLE_REDEF_IO) */
  return TCL_OK;
}

Changes to src/test_config.c.

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...
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...
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** 
** This file contains code used for testing the SQLite system.
** None of the code in this file goes into a deliverable build.
** 
** The focus of this file is providing the TCL testing layer
** access to compile-time constants.
**
** $Id: test_config.c,v 1.8 2007/08/20 17:37:48 shess Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

#ifdef SQLITE_ENABLE_FTS2
  Tcl_SetVar2(interp, "sqlite_options", "fts2", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "fts2", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_ENABLE_FTS3
  Tcl_SetVar2(interp, "sqlite_options", "fts3", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "fts3", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_GLOBALRECOVER
  Tcl_SetVar2(interp, "sqlite_options", "globalrecover", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "globalrecover", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_ENABLE_ICU
................................................................................

#ifdef SQLITE_OMIT_TCL_VARIABLE
  Tcl_SetVar2(interp, "sqlite_options", "tclvar", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "tclvar", "1", TCL_GLOBAL_ONLY);
#endif

#if defined(THREADSAFE) && THREADSAFE
  Tcl_SetVar2(interp, "sqlite_options", "threadsafe", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "threadsafe", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_TRACE
  Tcl_SetVar2(interp, "sqlite_options", "trace", "0", TCL_GLOBAL_ONLY);







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** 
** This file contains code used for testing the SQLite system.
** None of the code in this file goes into a deliverable build.
** 
** The focus of this file is providing the TCL testing layer
** access to compile-time constants.
**
** $Id: test_config.c,v 1.9 2007/08/20 22:48:43 drh Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

................................................................................

#ifdef SQLITE_ENABLE_FTS2
  Tcl_SetVar2(interp, "sqlite_options", "fts2", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "fts2", "0", TCL_GLOBAL_ONLY);
#endif







#ifdef SQLITE_OMIT_GLOBALRECOVER
  Tcl_SetVar2(interp, "sqlite_options", "globalrecover", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "globalrecover", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_ENABLE_ICU
................................................................................

#ifdef SQLITE_OMIT_TCL_VARIABLE
  Tcl_SetVar2(interp, "sqlite_options", "tclvar", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "tclvar", "1", TCL_GLOBAL_ONLY);
#endif

#if SQLITE_THREADSAFE
  Tcl_SetVar2(interp, "sqlite_options", "threadsafe", "1", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "threadsafe", "0", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_TRACE
  Tcl_SetVar2(interp, "sqlite_options", "trace", "0", TCL_GLOBAL_ONLY);

Changes to src/test_server.c.

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** to be deallocated before the new integer value is inserted.  In
** the case of sqlite3_column_int(), the value of the column might be
** a UTF-16 string which will need to be converted to UTF-8 then into
** an integer.
*/

/*
** Only compile the code in this file on UNIX with a THREADSAFE build
** and only if the SQLITE_SERVER macro is defined.
*/
#if defined(SQLITE_SERVER) && !defined(SQLITE_OMIT_SHARED_CACHE)
#if defined(OS_UNIX) && OS_UNIX && defined(THREADSAFE) && THREADSAFE

/*
** We require only pthreads and the public interface of SQLite.
*/
#include <pthread.h>
#include "sqlite3.h"

................................................................................
void sqlite3_server_stop(void){
  g.serverHalt = 1;
  pthread_cond_broadcast(&g.serverWakeup);
  pthread_mutex_lock(&g.serverMutex);
  pthread_mutex_unlock(&g.serverMutex);
}

#endif /* defined(OS_UNIX) && OS_UNIX && defined(THREADSAFE) && THREADSAFE */
#endif /* defined(SQLITE_SERVER) */







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** to be deallocated before the new integer value is inserted.  In
** the case of sqlite3_column_int(), the value of the column might be
** a UTF-16 string which will need to be converted to UTF-8 then into
** an integer.
*/

/*
** Only compile the code in this file on UNIX with a SQLITE_THREADSAFE build
** and only if the SQLITE_SERVER macro is defined.
*/
#if defined(SQLITE_SERVER) && !defined(SQLITE_OMIT_SHARED_CACHE)
#if defined(OS_UNIX) && OS_UNIX && SQLITE_THREADSAFE

/*
** We require only pthreads and the public interface of SQLite.
*/
#include <pthread.h>
#include "sqlite3.h"

................................................................................
void sqlite3_server_stop(void){
  g.serverHalt = 1;
  pthread_cond_broadcast(&g.serverWakeup);
  pthread_mutex_lock(&g.serverMutex);
  pthread_mutex_unlock(&g.serverMutex);
}

#endif /* defined(OS_UNIX) && OS_UNIX && SQLITE_THREADSAFE */
#endif /* defined(SQLITE_SERVER) */