** 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 1.660 2009/07/08 13:55:29 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
** Including a description of file format and an overview of operation.
*/
#include "btreeInt.h"

................................................................................
      return SQLITE_CORRUPT_BKPT;
    }
#else
    if( cbrk<iCellFirst || pc+size>usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
#endif
    assert( cbrk+size<=usableSize && cbrk>=iCellFirst );
    testcase( cbrk+size==usableSize );
    testcase( cbrk==iCellFirst );
    testcase( pc+size==usableSize );
    memcpy(&data[cbrk], &temp[pc], size);
    put2byte(pAddr, cbrk);
  }
  assert( cbrk>=iCellFirst );
  put2byte(&data[hdr+5], cbrk);
  data[hdr+1] = 0;
................................................................................
  ** freeblocks that overlapped cells.  If there was overlap then
  ** subsequent insert operations might have corrupted the freelist.
  ** So we do need to check for corruption while scanning the freelist.
  */
  hdr = pPage->hdrOffset;
  addr = hdr + 1;
  iLast = pPage->pBt->usableSize - 4;

  while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
    if( pbegin>iLast || pbegin<addr+4 ){
      return SQLITE_CORRUPT_BKPT;
    }
    addr = pbegin;
  }
  if( pbegin>iLast ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
    }
#endif
  }
  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
  ** restoreCursorPosition() here.
................................................................................
  restoreCursorPosition(pCur);
  pPage = pCur->apPage[pCur->iPage];
  assert( cursorHoldsMutex(pCur) );
  assert( pPage!=0 );
  assert( pPage->pBt==pCur->pBt );
  return pPage->aData[pPage->hdrOffset];
}


#ifndef SQLITE_OMIT_BTREECOUNT
/*
** The first argument, pCur, is a cursor opened on some b-tree. Count the
** number of entries in the b-tree and write the result to *pnEntry.
**
** SQLITE_OK is returned if the operation is successfully executed. 

** 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 1.661 2009/07/08 15:14:50 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"

................................................................................
      return SQLITE_CORRUPT_BKPT;
    }
#else
    if( cbrk<iCellFirst || pc+size>usableSize ){
      return SQLITE_CORRUPT_BKPT;
    }
#endif
    assert( cbrk+size<=usableSize && cbrk>iCellFirst );
    testcase( cbrk+size==usableSize );

    testcase( pc+size==usableSize );
    memcpy(&data[cbrk], &temp[pc], size);
    put2byte(pAddr, cbrk);
  }
  assert( cbrk>=iCellFirst );
  put2byte(&data[hdr+5], cbrk);
  data[hdr+1] = 0;
................................................................................
  ** freeblocks that overlapped cells.  If there was overlap then
  ** subsequent insert operations might have corrupted the freelist.
  ** So we do need to check for corruption while scanning the freelist.
  */
  hdr = pPage->hdrOffset;
  addr = hdr + 1;
  iLast = pPage->pBt->usableSize - 4;
  assert( start<=iLast );
  while( (pbegin = get2byte(&data[addr]))<start && pbegin>0 ){
    if( pbegin<addr+4 ){
      return SQLITE_CORRUPT_BKPT;
    }
    addr = pbegin;
  }
  if( pbegin>iLast ){
    return SQLITE_CORRUPT_BKPT;
  }
................................................................................
    }
#endif
  }
  sqlite3BtreeLeave(p);
  return rc;
}

#ifndef SQLITE_TEST
/*
** 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
  ** restoreCursorPosition() here.
................................................................................
  restoreCursorPosition(pCur);
  pPage = pCur->apPage[pCur->iPage];
  assert( cursorHoldsMutex(pCur) );
  assert( pPage!=0 );
  assert( pPage->pBt==pCur->pBt );
  return pPage->aData[pPage->hdrOffset];
}
#endif

#ifndef SQLITE_OMIT_BTREECOUNT
/*
** The first argument, pCur, is a cursor opened on some b-tree. Count the
** number of entries in the b-tree and write the result to *pnEntry.
**
** SQLITE_OK is returned if the operation is successfully executed.