SQLite

** Clear operations are exceedingly rare.  There are usually between
** 5 and 500 set operations per Bitvec object, though the number of sets can
** sometimes grow into tens of thousands or larger.  The size of the
** Bitvec object is the number of pages in the database file at the
** start of a transaction, and is thus usually less than a few thousand,
** but can be as large as 2 billion for a really big database.
**
** @(#) $Id: bitvec.c,v 1.10 2009/01/02 21:39:39 drh Exp $
*/
#include "sqliteInt.h"

/* Size of the Bitvec structure in bytes. */
#define BITVEC_SZ        512

/* Round the union size down to the nearest pointer boundary, since that's how 

  assert( i>0 );
  assert( i<=p->iSize );
  i--;
  while((p->iSize > BITVEC_NBIT) && p->iDivisor) {
    u32 bin = i/p->iDivisor;
    i = i%p->iDivisor;
    if( p->u.apSub[bin]==0 ){

      p->u.apSub[bin] = sqlite3BitvecCreate( p->iDivisor );

      if( p->u.apSub[bin]==0 ) return SQLITE_NOMEM;
    }
    p = p->u.apSub[bin];
  }
  if( p->iSize<=BITVEC_NBIT ){
    p->u.aBitmap[i/BITVEC_SZELEM] |= 1 << (i&(BITVEC_SZELEM-1));
    return SQLITE_OK;

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.528 2009/01/02 21:39:39 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/

}

/*
** Set the bit number pgno in the PagerSavepoint.pInSavepoint bitvecs of
** all open savepoints.
*/
static int addToSavepointBitvecs(Pager *pPager, Pgno pgno){
  int ii;                   /* Loop counter */
  int rc = SQLITE_OK;       /* Result code */

  for(ii=0; ii<pPager->nSavepoint; ii++){
    PagerSavepoint *p = &pPager->aSavepoint[ii];
    if( pgno<=p->nOrig ){

      rc |= sqlite3BitvecSet(p->pInSavepoint, pgno);
      assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
    }
  }
  return rc;
}

/*
** Unlock the database file. 
**
** If the pager is currently in error state, discard the contents of 
** the cache and reset the Pager structure internal state. If there is

        */
        if( rc!=SQLITE_OK ){
          return rc;
        }

        pPager->nRec++;
        assert( pPager->pInJournal!=0 );
        rc = sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
        testcase( rc==SQLITE_NOMEM );
        assert( rc==SQLITE_OK || rc==SQLITE_NOMEM );
        rc |= addToSavepointBitvecs(pPager, pPg->pgno);
        if( rc!=SQLITE_OK ){
          assert( rc==SQLITE_NOMEM );
          return rc;
        }
      }else{
        if( !pPager->journalStarted && !pPager->noSync ){
          pPg->flags |= PGHDR_NEED_SYNC;
          pPager->needSync = 1;
        }
        PAGERTRACE4("APPEND %d page %d needSync=%d\n",
                PAGERID(pPager), pPg->pgno,

      }
      PAGERTRACE3("STMT-JOURNAL %d page %d @ %d\n", PAGERID(pPager), pPg->pgno);
      if( rc!=SQLITE_OK ){
        return rc;
      }
      pPager->stmtNRec++;
      assert( pPager->nSavepoint>0 );
      rc = addToSavepointBitvecs(pPager, pPg->pgno);
      if( rc!=SQLITE_OK ){
        assert( rc==SQLITE_NOMEM );
        return rc;
      }
    }
  }

  /* Update the database size and return.
  */
  assert( pPager->state>=PAGER_SHARED );
  if( pPager->dbSize<pPg->pgno ){

** If we have not yet actually read the content of this page (if
** the PgHdr.needRead flag is set) then this routine acts as a promise
** that we will never need to read the page content in the future.
** so the needRead flag can be cleared at this point.
*/
void sqlite3PagerDontRollback(DbPage *pPg){
  Pager *pPager = pPg->pPager;
  TESTONLY( int rc; )  /* Return value from sqlite3BitvecSet() */

  assert( pPager->state>=PAGER_RESERVED );

  /* If the journal file is not open, or DontWrite() has been called on
  ** this page (DontWrite() sets the alwaysRollback flag), then this
  ** function is a no-op.
  */

  ** (Later:)  Not true.  If the database is corrupted by having duplicate
  ** pages on the freelist (ex: corrupt9.test) then the following is not
  ** necessarily true:
  */
  /* assert( !pPg->inJournal && (int)pPg->pgno <= pPager->dbOrigSize ); */

  assert( pPager->pInJournal!=0 );

  pPg->flags &= ~PGHDR_NEED_READ;

  /* Failure to set the bits in the InJournal bit-vectors is benign.
  ** It merely means that we might do some extra work to journal a page
  ** that does not need to be journal.  Nevertheless, be sure to test the
  ** case where a malloc error occurs while trying to set a bit in a 
  ** bit vector.
  */
  sqlite3BeginBenignMalloc();
  TESTONLY( rc = ) sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
  testcase( rc==SQLITE_NOMEM );
  TESTONLY( rc = ) addToSavepointBitvecs(pPager, pPg->pgno);
  testcase( rc==SQLITE_NOMEM );
  sqlite3EndBenignMalloc();


  PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
  IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))
}


/*
** This routine is called to increment the database file change-counter,

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.818 2009/01/02 21:39:39 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build

** both true and false in order to get full branch coverage.
** This macro can be inserted to ensure adequate test coverage
** in places where simple condition/decision coverage is inadequate.
*/
#ifdef SQLITE_COVERAGE_TEST
  void sqlite3Coverage(int);
# define testcase(X)  if( X ){ sqlite3Coverage(__LINE__); }
# define TESTONLY(X)  X
#else
# define testcase(X)
# define TESTONLY(X)
#endif

/*
** The ALWAYS and NEVER macros surround boolean expressions which 
** are intended to always be true or false, respectively.  Such
** expressions could be omitted from the code completely.  But they
** are included in a few cases in order to enhance the resilience