SQLite

** 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 1.536 2009/01/07 10:35:19 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

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

** moved as part of a database reorganization just before the transaction 
** is being committed. In this case, it is guaranteed that the database page 
** pPg refers to will not be written to again within this transaction.
*/
int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
  PgHdr *pPgOld;  /* The page being overwritten. */
  Pgno needSyncPgno = 0;
  int rc;

  assert( pPg->nRef>0 );

  /* If the page being moved is dirty and has not been saved by the latest
  ** savepoint, then save the current contents of the page into the 
  ** sub-journal now. This is required to handle the following scenario:
  **
  **   BEGIN;
  **     <journal page X, then modify it in memory>
  **     SAVEPOINT one;
  **       <Move page X to location Y>
  **     ROLLBACK TO one;
  **
  ** If page X were not written to the sub-journal here, it would not
  ** be possible to restore its contents when the "ROLLBACK TO one"
  ** statement were processed.
  */
  if( pPg->flags&PGHDR_DIRTY 
   && subjRequiresPage(pPg)
   && SQLITE_OK!=(rc = subjournalPage(pPg))
  ){
    return rc;
  }

  PAGERTRACE(("MOVE %d page %d (needSync=%d) moves to %d\n", 
      PAGERID(pPager), pPg->pgno, (pPg->flags&PGHDR_NEED_SYNC)?1:0, pgno));
  IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))

  pager_get_content(pPg);

    ** this transaction, it may be written to the database file before
    ** it is synced into the journal file. This way, it may end up in
    ** the journal file twice, but that is not a problem.
    **
    ** The sqlite3PagerGet() call may cause the journal to sync. So make
    ** sure the Pager.needSync flag is set too.
    */

    PgHdr *pPgHdr;
    assert( pPager->needSync );
    rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr);
    if( rc!=SQLITE_OK ){
      if( pPager->pInJournal && needSyncPgno<=pPager->dbOrigSize ){
        sqlite3BitvecClear(pPager->pInJournal, needSyncPgno);
      }

# 2008 December 15
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#
# $Id: savepoint.test,v 1.10 2009/01/07 10:35:19 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl


#----------------------------------------------------------------------
# The following tests - savepoint-1.* - test that the SAVEPOINT, RELEASE

do_test savepoint-11.6 {
  execsql { 
    CREATE TABLE t3(a, b, UNIQUE(a, b));
    ROLLBACK TO one;
  }
} {}
integrity_check savepoint-11.7
do_test savepoint-11.8 {
  execsql { ROLLBACK }
  file size test.db
} {8192}


do_test savepoint-11.9 {
  execsql {
    DROP TABLE IF EXISTS t1;
    DROP TABLE IF EXISTS t2;
    DROP TABLE IF EXISTS t3;
  }
} {}
do_test savepoint-11.10 {
  execsql {
    BEGIN;
      CREATE TABLE t1(a, b);
      CREATE TABLE t2(x, y);
      INSERT INTO t2 VALUES(1, 2);
      SAVEPOINT one;
        INSERT INTO t2 VALUES(3, 4);
        SAVEPOINT two;
          DROP TABLE t1;
        ROLLBACK TO two;
  }
  execsql {SELECT * FROM t2}
} {1 2 3 4}
do_test savepoint-11.11 {
  execsql COMMIT
} {}
do_test savepoint-11.12 {
  execsql {SELECT * FROM t2}
} {1 2 3 4}

#-------------------------------------------------------------------------
# The following tests - savepoint-12.* - test the interaction of 
# savepoints and "ON CONFLICT ROLLBACK" clauses.
# 
do_test savepoint-12.1 {
  execsql {
    CREATE TABLE t4(a PRIMARY KEY, b);